explanation      blue bibcodes open ADS page with paths to full text
Author name code: opher
ADS astronomy entries on 2022-09-14
author:"Opher, Merav," 

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Title: Near-Earth Supernovae in the Past 10 Myr: Implications for
    the Heliosphere
Authors: Miller, Jesse A.; Fields, Brian D.; Chen, Thomas Y.;
   Ellis, John; Ertel, Adrienne F.; Manweiler, Jerry W.; Opher, Merav;
   Provornikova, Elena; Slavin, Jonathan D.; Sokół, Justyna; Sterken,
   Veerle; Surman, Rebecca; Wang, Xilu
2022arXiv220903497M    Altcode:
  We summarize evidence that multiple supernovae exploded within 100
  pc of Earth in the past few Myr. These events had dramatic effects
  on the heliosphere, compressing it to within ~20 au. We advocate
  for cross-disciplinary research of nearby supernovae, including on
  interstellar dust and cosmic rays. We urge for support of theory work,
  direct exploration, and study of extrasolar astrospheres.

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Title: To Boldly Go, Where No One Has Gone Before: Overview of the
    Science Discoveries Enabled by an Interstellar Probe in the 2030's
Authors: Brandt, Pontus; Roelof, Edmond; Kurth, William; Provornikova,
   Elena; Opher, Merav; McNutt, Ralph; Galli, Andre; Hill, Matthew; Wurz,
   Peter; Bale, Stuart; Lisse, Carey; Kollmann, Peter; Demajistre, Robert;
   Zemcov, Michael; Mandt, Kathleen; Rymer, Abi; Beichman, Charles;
   Linsky, Jeffrey; Runyon, Kirby; Mostafavi, Parisa; Redfield, Seth;
   Turner, Drew
2022cosp...44.3194B    Altcode:
  For the past 60, 000 years our Sun and its protective heliosphere
  have been plowing through the Local Interstellar Cloud (LIC), but is
  now in a historic transition region towards the G-cloud that could
  have dramatic consequences for the global heliospheric structure. An
  Interstellar Probe mission to the Very Local Interstellar Medium (VLISM)
  would bring new scientific discoveries of the mechanisms upholding our
  vast heliosphere and directly sample the Local Interstellar Clouds to
  allow us, not only to understand the current dynamics and shielding,
  but also how the heliosphere responded in the past and how it will
  respond in the new interstellar environment. An international team
  of scientists and experts have now completed a NASA-funded study led
  by The Johns Hopkins University Applied Physics Laboratory (APL) to
  develop pragmatic example mission concepts for an Interstellar Probe
  with a nominal design lifetime of 50 years. The team has analyzed dozens
  of launch configurations and demonstrated that asymptotic speeds in
  excess of 7.5 Astronomical Units (AU) per year can be achieved using
  existing or near-term propulsion stages with a powered or passive
  Jupiter Gravity Assist (JGA). These speeds are more than twice that
  of the fastest escaping man-made spacecraft to date, which is Voyager
  1 currently at 3.59 AU/year. An Interstellar Probe would therefore
  reach the Termination Shock (TS) in less than 12 years and cross
  the Heliopause into the VLISM after about 16 years from launch. In
  this presentation we provide an overview of the study, the science
  mission concept, discuss the compelling discoveries that await, and
  the associated example science payload, measurements and operations
  ensuring a historic data return that would push the boundaries of
  space exploration by going where no one has gone before.

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Title: On the energization of pickup ions downstream of the
    heliosheric termination shock, by comparing 0.52-55 keV observed
    ENA spectra to simulated ENAs inferred by proton hybrid simulations.
Authors: Gkioulidou, Matina; Richardson, John; Mitchell, Donald; Opher,
   Merav; Krimigis, Stamatios; Zank, Gary; Giacalone, Joe; Fuselier,
   Stephen; Dialynas, Konstantinos; Baliukin, Igor; Kornbleuth, Marc;
   Roussos, Elias; Gkioulidou, Matina
2022cosp...44.1315G    Altcode:
  As the solar system and its surrounding heliosphere move through the
  local interstellar medium, interstellar neutral atoms, mostly atomic
  Hydrogen, enter the heliosphere and undergo charge-exchange collisions
  with the continuously flowing solar wind protons. Newly created
  ions from the interstellar neutral population are advected outward
  with the solar wind, forming a population that is commonly known as
  pickup ions (PUIs). When PUIs reach the termination shock, they are
  heated, with a fraction of their distribution being reflected off the
  shock surface and undergoing additional heating. The heated PUIs that
  populate the heliosheath (HS), charge-exchange with the interstellar
  neutrals, creating Energetic Neutral Atoms (ENAs) that are measured
  remotely by the Interstellar Boundary Explorer (IBEX; 0.01-6 keV)
  and Cassini/Ion and Neutral Camera (INCA; 5.2-55 keV). Understanding
  the PUI distribution in the heliosheath is essential in order to i)
  study the pressure balance and acceleration mechanisms inside the
  heliosheath, and ii) to determine the ENA emission from the heliosheath,
  since these ENAs are used to remotely sense the boundaries of our
  heliosphere and its interaction with the very local interstellar
  medium. In this study, we present an unprecedented comparison of ~
  0.52 - 55 keV Energetic Neutral Atom (ENA) heliosheath measurements,
  remotely sensed by the Interstellar Boundary Explorer (IBEX) mission
  and the Ion and Neutral Camera (INCA) on the Cassini mission, with
  modeled ENA inferred from interstellar pickup protons that have been
  accelerated at the termination shock using hybrid simulations, towards
  assessing the PUI energetics within the heliosheath. This is the first
  study to use hybrid simulations that are able to accurately model the
  acceleration of ions to 10s of keV energies, which is essential in
  order to model ENA fluxes in the heliosheath, covering the full energy
  range observed by IBEX and CASSINI/INCA. The observed ENA intensities
  are an average value over the time period from 2009 to the end of
  2012, along the Voyager 2 trajectory. The hybrid simulations upstream
  of the termination shock, where Voyager 2 crossed, are constrained
  by observations. We report an energy dependent discrepancy between
  observed and simulated ENA fluxes, with the observed ENA fluxes, being
  persistently higher than the simulated ones. Our analysis reveals that
  the termination shock may not accelerate pick up ions to sufficient
  energies to account for the observed ENA fluxes. We, thus, suggest
  that the further acceleration of these pick up ions is most likely
  occurring within the heliosheath, via additional physical processes
  like turbulence or magnetic reconnection. Yet, the redistribution of
  energy inside the heliosheath remains an open question.

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Title: Climate Change and Human Evolution from the Passage of the
    Solar System through a Cold Cloud 2-3Myrs ago
Authors: Opher, Merav; Loeb, Abraham
2022cosp...44.3203O    Altcode:
  There is overwhelming geological evidence from 60Fe and 244Pu isotopes
  that Earth was in direct contact with the interstellar medium (ISM)
  2-3 Myr ago. The local interstellar medium is home to several nearby
  cold clouds. Here we show that if the solar system passed through
  a cloud such as Local Leo Cold Cloud, then the heliosphere which
  protects the solar system from interstellar particles, had shrunk to
  a scale smaller than the Earth's orbit around the Sun (0.22AU). Using
  a magnetohydrodynamic simulation that includes charge exchange between
  neutral atoms and ions, we show that during the heliosphere shrinkage,
  Earth was exposed to a neutral hydrogen density of up to 3000cm-3. This
  could have had drastic effects on Earth's climate and potentially of
  human evolution at that time, as suggested by previous data.

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Title: Considerations of the Global Heliopause Boundary Using
    Macroscopic, Multipoint Voyager Observations in the Context of
    Microscopic, Multipoint MMS Observations at Earth's Magnetopause
Authors: Turner, Drew; Provornikova, Elena; Opher, Merav; Hill,
   Matthew; Brandt, Pontus; Lavraud, Benoit; Schwadron, Nathan; Eriksson,
   Stefan; Kornbleuth, Marc; Cohen, Ian; Westlake, Joseph; Clark, George;
   McComas, David; Mostafavi, Parisa; Michael, Adam
2022cosp...44.1314T    Altcode:
  Voyager-1 and -2 encountered a clear plasma boundary between the
  solar-dominated heliosheath and the apparent very local interstellar
  medium (VLISM) at heliocentric distances of 121.7 AU in August 2012 and
  118.0 AU in November 2018, respectively. One intriguing mystery of the
  Voyagers' crossings of the heliopause was that both spacecraft found
  that the magnetic fields on either side of the boundary were generally
  parallel to each other; that is, at both Voyager-1 and Voyager-2 in
  their divergent crossing locations along the heliopause, the solar
  magnetic field on the inside of the heliopause was essentially parallel
  to the interstellar magnetic field on the outside of the heliopause. In
  this study, we revisit these confounding and intriguing results
  by putting observations of magnetic fields and energetic particles
  at both Voyagers plus plasma data from Voyager-2 into context with
  magnetic field, plasma, and energetic particle data from Magnetospheric
  Multiscale (MMS) observations of crossings of Earth's magnetopause, an
  analogous boundary between two distinct plasma environments. With this
  combination of the two Voyagers as an enormous macroscope, providing
  details of the plasma conditions at two disparate locations around the
  upstream heliopause, alongside MMS observations as a precision "electron
  microscope" at a different yet analogous boundary, we offer new insight
  on interpretation of the Voyager observations. In particular, we address
  the possibility of active magnetic reconnection along the heliopause and
  implications considering IBEX results, NASA's upcoming IMAP mission, and
  a future Interstellar Probe. Our results indicate that both Voyagers may
  have crossed into an extended heliopause boundary layer resulting from
  active reconnection between interstellar magnetic fields and the Sun's
  interplanetary magnetic fields along the flanks of the heliopause. We
  estimate that - because of a combination of long-temporal stability
  of the interstellar magnetic field direction plus the extreme spatial
  distances (100s of AU along the nose-side heliopause) and relatively
  slow plasma speeds (advective flows and Alfvén speeds on the order
  of ~20 to 40 km/s) - the reconnected boundary layer may extend as far
  as several 10s of AU radially outward from the Voyagers' respective
  crossing points. Furthermore, because of the steady, solar-westward
  orientation of the magnetic field observed by the Voyagers in this
  boundary layer, we offer a prediction about which quadrant of the
  flank heliopause the reconnection occurred at for field lines mapping
  to both Voyager spacecraft. In future work, these predictions should
  be tested with state-of-the-art, global heliospheric models.

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Title: Lys/STELLA: H Lyman Alpha Spectrograph for the Interstellar
    Probe
Authors: Quemerais, Eric; Matta, Majd; Provornikova, Elena; Opher,
   Merav; Clarke, John; Koutroumpa, Dimitra
2022cosp...44.3207Q    Altcode:
  The Interstellar Probe project gives an unprecedented opportunity
  to study the hydrogen atom distribution from the interstellar medium
  to the inner heliosphere. The solar H Lyman alpha emission (121.6nm)
  is the brightest line in the UV range. Solar Lyman alpha photons are
  backscattered by hydrogen atoms in the interplanetary medium producing
  the interplanetary glow that extends far beyond the heliopause into
  the interstellar medium. A Lyman alpha spectrograph will measure the
  LISM H number density giving the first direct measurement of this
  quantity just outside of the heliospheric interface. This value is
  one of the critical parameters defining the size and behavior of the
  heliospheric interace. With a high resolution spectrograph, it will
  be possible to differentiate between the Lyman alpha galactic emission
  derived from the UVS-Voyager data and the LISM H Lyman alpha emission
  from the line of sight velocity of the atoms. Because of resonant
  charge exchange between the hydrogen atoms and the protons, the H
  atom distribution is strongly affected when the neutrals cross the
  heliospheric interface region. H atoms created after charge exchange
  keep the velocity distribution of the protons that they were created
  from. Therefore, the backscattered Lyman alpha line profile will change
  as the interstellar probe crosses through the inner heliosheath to
  the outer heliosheath and then moves into the LISM, providing a test
  on the proton distribution in the heliosphere regions crossed by the
  interstellar probe. Here, we will present an instrumental design that
  will allow for this study bringing new information on the heliospheric
  interface and the very local interstellar medium.

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Title: On the Energy Dependence of Galactic Cosmic Ray Anisotropies
    in the Very Local Interstellar Medium
Authors: Nikoukar, Romina; Hill, Matthew E.; Brown, Lawrence; Kota,
   Jozsef; Decker, Robert B.; Dialynas, Konstantinos; Hamilton, Douglas
   C.; Krimigis, Stamatios M.; Lasley, Scott; Roelof, Edmond C.; Mitchell,
   J. Grant; Florinski, Vladimir.; Giacalone, Joe.; Richardson, John;
   Opher, Merav
2022ApJ...934...41N    Altcode: 2022arXiv220107844N
  We report on the energy dependence of Galactic cosmic rays (GCRs)
  in the very local interstellar medium (VLISM) as measured by the
  Low Energy Charged Particle (LECP) instrument on the Voyager 1
  spacecraft. The LECP instrument includes a dual-ended solid-state
  detector particle telescope mechanically scanning through 360° across
  eight equally spaced angular sectors. As reported previously, LECP
  measurements showed a dramatic increase in GCR intensities for all
  sectors of the ≥211 MeV count rate (CH31) at the Voyager 1 heliopause
  (HP) crossing in 2012; however, since then the count rate data have
  demonstrated systematic episodes of intensity decrease for particles
  around 90° pitch angle. To shed light on the energy dependence of
  these GCR anisotropies over a wide range of energies, we use Voyager
  1 LECP count rate and pulse height analyzer (PHA) data from ≥211
  MeV channel together with lower-energy LECP channels. Our analysis
  shows that, while GCR anisotropies are present over a wide range of
  energies, there is a decreasing trend in the amplitude of second-order
  anisotropy with increasing energy during anisotropy episodes. A stronger
  pitch angle scattering at higher velocities is argued as a potential
  cause for this energy dependence. A possible cause for this velocity
  dependence arising from weak rigidity dependence of the scattering
  mean free path and resulting velocity-dominated scattering rate is
  discussed. This interpretation is consistent with a recently reported
  lack of corresponding GCR electron anisotropies.

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Title: Societal and Science Case For Inner Heliospheric Solar Wind
    Constellation
Authors: Nykyri, Katariina; Balikhin, Michael A.; Wing, Simon; Opher,
   Merav; Sibeck, David; Hesse, Michael; Ebert, Robert; Fuselier, Stephen;
   Ma, Xuanye; Burkholder, Brandon; Parker, Jeffrey; Cuellar Rangel,
   Roberto; Liou, Yu-Lun; Broll, Jeffrey; Wilder, Rick; Holland, Katherine
2022cosp...44.1607N    Altcode:
  The solar wind exhibits large-scale and mesoscale structures whose
  presence and evolution directly affect Earth's space environment and
  can impact key assets on and orbiting Earth. Phenomena such as coronal
  mass ejections, co-rotating interaction regions, and interplanetary
  shocks can have rapid and dramatic geospace effects via large-scale
  fluctuations in the interplanetary magnetic field, plasma pressure
  and density, and solar energetic particle (SEP) energization and
  propagation. Satellite constellations at the Earth-Sun Lagrange 1
  (L1) point can only provide solar wind plasma and magnetic field
  measurements ~ 1 hr in advance of their arrival at Earth, limiting
  our ability to forecast significant events and avoid technological
  and societal disaster; the recent loss of 40 Starlink satellites due
  to geomagnetic storm activity, for example, highlights the need for
  1-2 day advanced space weather forecasts. To prepare our technological
  society for the next decade and beyond, we need to have a network of
  upstream spacecraft at various radial distances from Sun whose data
  could be assimilated near real-time into space weather modeling. This
  could be achieved by placing constellations at the Mercury, Venus and
  Earth Lagrange points, which - with international collaboration is
  possible over - the coming decades. As a first step, we propose the
  first of its kind Pathfinder mission, placing spacecraft into Venus-Sun
  Lagrange points to enable study of the physical processes responsible
  for the large- to meso-scale plasma and magnetic structures in the
  inner heliosphere and energetic particle dynamics. This mission will
  provide the first in-situ, synchronized, multi-point magnetic field
  and energetic particle measurements in a region only sparsely covered
  by single-point measurements from flybys of sun- and Mercury-bound
  missions since the end of Venus Express in 2014. When one or more
  of the Venus-Sun Lagrange points lies sunward from the Earth and/or
  further towards the west limb of the Sun, a coverage period of ~50
  Days/Earth year, these observations would allow us to develop and
  test space weather warning algorithms based on coronagraphs and
  in-situ observations of the solar wind at L1; even when not in the
  flight path of Earthward-bound solar wind, the multiscale nature of
  the observations would provide key insight into the propagation and
  evolution of solar wind structures.

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Title: Correction to: Interstellar Neutrals, Pickup Ions, and
Energetic Neutral Atoms Throughout the Heliosphere: Present Theory
    and Modeling Overview
Authors: Sokół, Justyna M.; Kucharek, Harald; Baliukin, Igor I.;
   Fahr, Hans; Izmodenov, Vladislav V.; Kornbleuth, Marc; Mostafavi,
   Parisa; Opher, Merav; Park, Jeewoo; Pogorelov, Nikolai V.; Quinn,
   Philip R.; Smith, Charles W.; Zank, Gary P.; Zhang, Ming
2022SSRv..218...25S    Altcode:
  No abstract at ADS

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Title: Terrestrial Impact from the Passage of the Solar System
    through a Cold Cloud a Few Million Years Ago
Authors: Opher, Merav; Loeb, Abraham
2022AAS...24022706O    Altcode:
  It is expected that as the Sun travels through the interstellar medium
  (ISM), there will be different filtration of Galactic Cosmic Rays
  (GCR) that affect Earth. The effect of GCR on Earth's atmosphere and
  climate is still uncertain. Although the interaction with molecular
  clouds was previously considered, the terrestrial impact of compact
  cold clouds was neglected. There is overwhelming geological evidence
  from <SUP>60</SUP>Fe and <SUP>244</SUP>Pu isotopes that Earth was in
  direct contact with the ISM 2-3 million years ago, and the local ISM
  is home to several nearby cold clouds. Here we show, with a state-of
  the art simulation that incorporate all the current knowledge about
  the heliosphere that if the solar system passed through a cloud
  such as Local Leo Cold Cloud, then the heliosphere which protects
  the solar system from interstellar particles, must have shrunk to a
  scale smaller than the Earth's orbit around the Sun (0.22 AU). Using
  a magnetohydrodynamic simulation that includes charge exchange
  between neutral atoms and ions, we show that during the heliosphere
  shrinkage, Earth was exposed to a neutral hydrogen density of up to
  3000 cm<SUP>-3</SUP>. This could have had drastic effects on Earth's
  climate and potentially on human evolution at that time, as suggested
  by existing data.

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Title: MSWIM2D: Two-dimensional Outer Heliosphere Solar Wind Modeling
Authors: Keebler, Timothy B.; Tóth, Gábor; Zieger, Bertalan;
   Opher, Merav
2022ApJS..260...43K    Altcode:
  The vast size of the Sun's heliosphere, combined with sparse
  spacecraft measurements over that large domain, makes numerical
  modeling a critical tool to predict solar wind conditions where there
  are no measurements. This study models the solar wind propagation
  in 2D using the BATSRUS MHD solver to form the MSWIM2D data set of
  solar wind in the outer heliosphere. Representing the solar wind
  from 1 to 75 au in the ecliptic plane, a continuous model run from
  1995-present has been performed. The results are available for free
  at http://csem.engin.umich.edu/mswim2d/. The web interface extracts
  output at desired locations and times. In addition to solar wind ions,
  the model includes neutrals coming from the interstellar medium to
  reproduce the slowing of the solar wind in the outer heliosphere and
  to extend the utility of the model to larger radial distances. The
  inclusion of neutral hydrogen is critical to recreating the solar
  wind accurately outside of ~4 au. The inner boundary is filled by
  interpolating and time-shifting in situ observations from L1 and
  STEREO spacecraft when available. Using multiple spacecraft provides
  a more accurate boundary condition than a single spacecraft with time
  shifting alone. Validations of MSWIM2D are performed using MAVEN and
  New Horizons observations. The results demonstrate the efficacy of
  this model to propagate the solar wind to large distances and obtain
  practical, useful solar wind predictions. For example, the rms error
  of solar wind speed prediction at Mars is only 66 km s<SUP>-1</SUP>
  and at Pluto is a mere 25 km s<SUP>-1</SUP>.

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Title: The Heliosphere and Local Interstellar Medium from Neutral
    Atom Observations at Energies Below 10 keV
Authors: Galli, André; Baliukin, Igor I.; Bzowski, Maciej; Izmodenov,
   Vladislav V.; Kornbleuth, Marc; Kucharek, Harald; Möbius, Eberhard;
   Opher, Merav; Reisenfeld, Dan; Schwadron, Nathan A.; Swaczyna, Paweł
2022SSRv..218...31G    Altcode:
  As the heliosphere moves through the surrounding interstellar medium,
  a fraction of the interstellar neutral helium, hydrogen, and heavier
  species crossing the heliopause make it to the inner heliosphere as
  neutral atoms with energies ranging from few eV to several hundred
  eV. In addition, energetic neutral hydrogen atoms originating from solar
  wind protons and from pick-up ions are created through charge-exchange
  with interstellar atoms.

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Title: On the Energization of Pickup Ions Downstream of the
    Heliospheric Termination Shock by Comparing 0.52-55 keV Observed
    Energetic Neutral Atom Spectra to Ones Inferred from Proton Hybrid
    Simulations
Authors: Gkioulidou, Matina; Opher, M.; Kornbleuth, M.; Dialynas,
   K.; Giacalone, J.; Richardson, J. D.; Zank, G. P.; Fuselier, S. A.;
   Mitchell, D. G.; Krimigis, S. M.; Roussos, E.; Baliukin, I.
2022ApJ...931L..21G    Altcode:
  We present an unprecedented comparison of ~0.52-55 keV energetic neutral
  atom (ENA) heliosheath measurements, remotely sensed by the Interstellar
  Boundary Explorer (IBEX) mission and the Ion and Neutral Camera (INCA)
  on the Cassini mission, with modeled ENAs inferred from interstellar
  pickup protons that have been accelerated at the termination shock,
  using hybrid simulations, to assess the pickup ion energetics within
  the heliosheath. This is the first study to use hybrid simulations
  that are able to accurately model the acceleration of ions to tens
  of keV energies, which is essential in order to model ENA fluxes in
  the heliosheath, covering the full energy range observed by IBEX and
  CASSINI/INCA. The observed ENA intensities are an average value over
  the time period from 2009 to the end of 2012, along the Voyager 2
  (V2) trajectory. The hybrid simulations upstream of the termination
  shock, where V2 crossed, are constrained by observations. We report
  an energy-dependent discrepancy between observed and simulated ENA
  fluxes, with the observed ENA fluxes being persistently higher than
  the simulated ones. Our analysis reveals that the termination shock
  may not accelerate pickup ions to sufficient energies to account
  for the observed ENA fluxes. We, thus, suggest that the further
  acceleration of these pickup ions is most likely occurring within
  the heliosheath, via additional physical processes like turbulence or
  magnetic reconnection. However, the redistribution of energy inside
  the heliosheath remains an open question.

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Title: The Structure of the Large-Scale Heliosphere as Seen by
    Current Models
Authors: Kleimann, Jens; Dialynas, Konstantinos; Fraternale, Federico;
   Galli, André; Heerikhuisen, Jacob; Izmodenov, Vladislav; Kornbleuth,
   Marc; Opher, Merav; Pogorelov, Nikolai
2022SSRv..218...36K    Altcode:
  This review summarizes the current state of research aiming at a
  description of the global heliosphere using both analytical and
  numerical modeling efforts, particularly in view of the overall
  plasma/neutral flow and magnetic field structure, and its relation
  to energetic neutral atoms. Being part of a larger volume on current
  heliospheric research, it also lays out a number of key concepts
  and describes several classic, though still relevant early works
  on the topic. Regarding numerical simulations, emphasis is put on
  magnetohydrodynamic (MHD), multi-fluid, kinetic-MHD, and hybrid modeling
  frameworks. Finally, open issues relating to the physical relevance of
  so-called "croissant" models of the heliosphere, as well as the general
  (dis)agreement of model predictions with observations are highlighted
  and critically discussed.

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Title: Thank You to Our 2021 Peer Reviewers
Authors: Rajaram, Harihar; Camargo, Suzana; Cappa, Christopher D.;
   Carey, Rebecca; Cory, Rose M.; Dombard, Andrew J.; Donohue, Kathleen
   A.; Flesch, Lucy; Giannini, Alessandra; Gu, Yu; Huber, Christian;
   Ivanov, Valeriy; Korte, Monika; Lu, Gang; Morlighem, Mathieu;
   Magnusdottir, Gudrun; Opher, Merav; Patricola, Christina M.; Prieto,
   Germán. A.; Qiu, Bo; Su, Hui; Sun, Daoyuan; Thornton, Joel A.; Wang,
   Kaicun; Whalen, Caitlin; White, Angelicque E.; Williams, Quentin;
   Yau, Andrew
2022GeoRL..4998947R    Altcode:
  No abstract at ADS

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Title: Interstellar Neutrals, Pickup Ions, and Energetic Neutral
Atoms Throughout the Heliosphere: Present Theory and Modeling Overview
Authors: Sokół, Justyna M.; Kucharek, Harald; Baliukin, Igor I.;
   Fahr, Hans; Izmodenov, Vladislav V.; Kornbleuth, Marc; Mostafavi,
   Parisa; Opher, Merav; Park, Jeewoo; Pogorelov, Nikolai V.; Quinn,
   Philip R.; Smith, Charles W.; Zank, Gary P.; Zhang, Ming
2022SSRv..218...18S    Altcode:
  Interstellar neutrals (ISNs), pick-up ions (PUIs), and energetic
  neutral atoms (ENAs) are fundamental constituents of the heliosphere
  and its interaction with the neighboring interstellar medium. Here, we
  focus on selected aspects of present-day theory and modeling of these
  particles. In the last decades, progress in the understanding of the
  role of PUIs and ENAs for the global heliosphere and its interaction
  with very local interstellar medium is impressive and still growing. The
  increasing number of measurements allows for verification and continuing
  development of the theories and model attempts. We present an overview
  of various model descriptions of the heliosphere and the processes
  throughout it including the kinetic, fluid, and hybrid solutions. We
  also discuss topics in which interplay between theory, models, and
  interpretation of measurements reveals the complexity of the heliosphere
  and its understanding. They include model-based interpretation of the
  ISN, PUI, and ENA measurements conducted from the Earth's vicinity. In
  addition, we describe selected processes beyond the Earth's orbit up to
  the heliosphere boundary regions, where PUIs significantly contribute
  to the complex system of the global heliosphere and its interaction
  with the VLISM.

---------------------------------------------------------
Title: Terrestrial Impact from the Passage of the Solar System
    through a Cold Cloud a Few Million Years Ago
Authors: Opher, Merav; Loeb, Abraham
2022arXiv220201813O    Altcode:
  It is expected that as the Sun travels through the interstellar medium
  (ISM), there will be different filtration of Galactic Cosmic Rays (GCR)
  that affect Earth. The effect of GCR on Earth's atmosphere and climate
  is still uncertain. Although the interaction with molecular clouds was
  previously considered, the terrestrial impact of compact cold clouds
  was neglected. There is overwhelming geological evidence from 60Fe and
  244Pu isotopes that Earth was in direct contact with the ISM 2 million
  years ago, and the local ISM is home to several nearby cold clouds. Here
  we show, with a state-of the art simulation that incorporate all the
  current knowledge about the heliosphere that if the solar system passed
  through a cloud such as Local Leo Cold Cloud, then the heliosphere which
  protects the solar system from interstellar particles, must have shrunk
  to a scale smaller than the Earth's orbit around the Sun (0.22). Using
  a magnetohydrodynamic simulation that includes charge exchange between
  neutral atoms and ions, we show that during the heliosphere shrinkage,
  Earth was exposed to a neutral hydrogen density of up to 3000cm-3. This
  could have had drastic effects on Earth's climate and potentially on
  human evolution at that time, as suggested by existing data.

---------------------------------------------------------
Title: The Solar Wind with Hydrogen Ion Exchange and Large-scale
Dynamics (SHIELD) Code: A Self-consistent Kinetic-Magnetohydrodynamic
    Model of the Outer Heliosphere
Authors: Michael, A. T.; Opher, M.; Tóth, G.; Tenishev, V.;
   Borovikov, D.
2022ApJ...924..105M    Altcode:
  Neutral hydrogen has been shown to greatly impact the plasma flow in
  the heliosphere and the location of the heliospheric boundaries. We
  present the results of the Solar Wind with Hydrogen Ion Exchange
  and Large-scale Dynamics (SHIELD) model, a new, self-consistent,
  kinetic-MHD model of the outer heliosphere within the Space Weather
  Modeling Framework. The charge exchange mean free path is on the
  order of the size of the heliosphere; therefore, the neutral atoms
  cannot be described as a fluid. The numerical code SHIELD couples
  the MHD solution for a single plasma fluid to the kinetic solution
  for neutral hydrogen atoms streaming through the system. The kinetic
  code is based on the Adaptive Mesh Particle Simulator, a Monte Carlo
  method for solving the Boltzmann equation. The numerical code SHIELD
  accurately predicts the increased filtration of interstellar neutrals
  into the heliosphere. In order to verify the correct implementation
  within the model, we compare the results of the numerical code SHIELD
  to those of other, well-established kinetic-MHD models. The numerical
  code SHIELD matches the neutral hydrogen solution of these studies
  as well as the shift in all heliospheric boundaries closer to the
  Sun in comparison with the multi-fluid treatment of neutral hydrogen
  atoms. Overall the numerical code SHIELD shows excellent agreement with
  these models and is a significant improvement to the fluid treatment
  of interstellar hydrogen.

---------------------------------------------------------
Title: Using Magnetic Flux Conservation to Determine Heliosheath
    Speeds
Authors: Richardson, John; Cummings, Alan; Burlaga, Leonard; Giacalone,
   Joe; Opher, Merav; Stone, Edward
2021AGUFMSH25C2104R    Altcode:
  The heliosheath (HSH) speeds at Voyager 2 (V2) derived from the plasma
  instrument (PLS) and from particle instruments using the Compton-Getting
  (CG) effect are very different. At V2 the CG speeds are more variable
  than the plasma speeds and decrease about two years before the
  heliopause. We use magnetic flux conservation to differentiate between
  these two speed profiles at V2, comparing the magnetic flux observed
  at 1 AU and in the HSH. For V2 the PLS speed profile is significantly
  more consistent with magnetic flux conservation than the CG speeds. For
  Voyager 1 (V1), we present new VR derivations from the cosmic ray
  subsystem (CRS) using the CG method that agree reasonably well with
  those previously obtained from the low energy charged particle (LECP)
  instrument. If we use the V2 PLS speed profile to calculate the magnetic
  flux at V1, we again find much better agreement than if we use the V1
  CG speeds. These results suggest that the radial speeds derived from
  particle anisotropy observations in the HSH may not be reliable.

---------------------------------------------------------
Title: A Turbulent Heliosheath Driven by the Rayleigh-Taylor
    Instability
Authors: Opher, M.; Drake, J. F.; Zank, G.; Powell, E.; Shelley, W.;
   Kornbleuth, M.; Florinski, V.; Izmodenov, V.; Giacalone, J.; Fuselier,
   S.; Dialynas, K.; Loeb, A.; Richardson, J.
2021ApJ...922..181O    Altcode:
  The heliosphere is the bubble formed by the solar wind as it interacts
  with the interstellar medium (ISM). The collimation of the heliosheath
  (HS) flows by the solar magnetic field in the heliotail into distinct
  north and south columns (jets) is seen in recent global simulations
  of the heliosphere. However, there is disagreement between the
  models about how far downtail the two-lobe feature persists and
  whether the ambient ISM penetrates into the region between the two
  lobes. Magnetohydrodynamic simulations show that these heliospheric jets
  become unstable as they move down the heliotail and drive large-scale
  turbulence. However, the mechanism that produces this turbulence had
  not been identified. Here we show that the driver of the turbulence
  is the Rayleigh-Taylor (RT) instability produced by the interaction
  of neutral H atoms streaming from the ISM with the ionized matter in
  the HS. The drag between the neutral and ionized matter acts as an
  effective gravity, which causes an RT instability to develop along the
  axis of the HS magnetic field. A density gradient exists perpendicular
  to this axis due to the confinement of the solar wind by the solar
  magnetic field. The characteristic timescale of the instability
  depends on the neutral H density in the ISM and for typical values
  the growth rate is ~3 years. The instability destroys the coherence
  of the heliospheric jets and magnetic reconnection ensues, allowing
  ISM material to penetrate the heliospheric tail. Signatures of this
  instability should be observable in Energetic Neutral Atom maps from
  future missions such as the Interstellar Mapping and Acceleration Probe
  (IMAP). The turbulence driven by the instability is macroscopic and
  potentially has important implications for particle acceleration.

---------------------------------------------------------
Title: 2D Michigan Solar Wind Propagation Model for the Outer
    Heliosphere
Authors: Keebler, Timothy; Toth, Gabor; Opher, Merav; Zieger, Bertalan
2021AGUFMSH25C2105K    Altcode:
  Modeling of the solar wind propagation through the Outer Heliosphere
  is critical for comparison with limited spacecraft data and to fill
  in an area with sparse in-situ observations. Following the MSWiM
  one-dimensional solar wind advection model, the Michigan Solar WInd
  Model in 2D (MSWIM2D) is presented to improve solar wind representation
  for the outer heliosphere in the ecliptic plane. This model is driven
  using data from observatories at the first Earth-Sun Lagrangian point,
  as well as the STEREO spacecraft, to fill the inner boundary at 1
  AU. By time-shifting the point observations and interpolating between
  multiple observatories, the entire inner boundary of Earth's orbit
  can be constantly populated by solar wind observations, permitting
  the driving of a 2D model. Interstellar neutrals are also included to
  interact with the solar wind, extending the model utility to larger
  radial distances. Validation at Mars using MAVEN data shows good
  agreement, and validation at New Horizons is presented here to assess
  model performance over longer propagations. The model output is publicly
  accessible for use by the broader planetary and heliospheric community,
  available at http://csem.engin.umich.edu/mswim2d. This interface allows
  interpolation of the model results along user-defined trajectories
  at one hour output cadence. Timeseries along the trajectories can be
  created between 1995 and 2020, and include solar wind density, vector
  velocity, vector magnetic field, and ion temperature.

---------------------------------------------------------
Title: A comparison of heliotail configurations arising from different
    treatments of non-ideal MHD effects with ENA maps at IBEX energies
Authors: Kornbleuth, Marc; Opher, Merav; Baliukin, Igor; Dayeh,
   Maher; Zirnstein, Eric; Gkioulidou, Matina; Dialynas, Kostas; Galli,
   Andre; Richardson, John; Izmodenov, Vladislav; Zank, Gary; Fuselier,
   Stephen A.; Michael, Adam; Toth, Gabor; Tenishev, Valeriy; Alexashov,
   Dmitry; Drake, James
2021AGUFMSH21B..02K    Altcode:
  The role of the solar magnetic field in the heliosheath has long
  been considered passive, but recent studies indicate it may play an
  active role in collimating the heliosheath plasma into two lobes at
  high latitudes. We compare results from two MHD models, the BU and
  Moscow models, which treat non-ideal MHD effects differently. The BU
  model allows for magnetic reconnection at the heliopause between the
  solar and interstellar magnetic fields, while the Moscow model does not
  allow for direct communication between the solar wind and interstellar
  medium. We use the same boundary conditions, 22-year averaged solar
  cycle conditions from 1995 to 2017. An important result is that
  both models show that the plasma in the heliosheath and heliotail is
  confined by the solar magnetic field in two lobes. The plasma solutions
  in the nose of the heliosphere are similar. However, the Moscow model
  displays a long, thousands of AU comet-like tail whereas the BU model
  shows the heliotail is shortened to about 400 AU where the interstellar
  medium flows between the two lobes. The ENA maps from the two models
  show both qualitative and quantitative agreement at IBEX energies,
  despite the different configurations of the heliotail. The modeled
  ENA maps agree qualitatively, but not quantitatively, with IBEX ENA
  observations. At higher energies the ENA maps from the two models
  differ, so higher energy ENA data (from INCA or IMAP) may be able to
  determine which model heliotail best fits the data.

---------------------------------------------------------
Title: A Turbulent Heliosheath Driven by Rayleigh Taylor Instability
Authors: Opher, Merav; Drake, James; Zank, Gary; Toth, Gabor; Powell,
   Erick; Kornbleuth, Marc; Florinski, Vladimir; Izmodenov, Vladislav;
   Giacalone, Joe; Fuselier, Stephen A.; Dialynas, Kostas; Loeb, Abraham;
   Richardson, John
2021AGUFMSH21B..06O    Altcode:
  The heliosphere is the bubble formed by the solar wind as it interacts
  with the interstellar medium (ISM). Studies show that the solar
  magnetic field funnels the heliosheath solar wind (the shocked solar
  wind at the edge of the heliosphere) into two jet-like structures
  (1-2). Magnetohydrodynamic simulations show that these heliospheric
  jets become unstable as they move down the heliotail (1-3) and drive
  large-scale turbulence. However, the mechanism that produces of this
  turbulence had not been identified. Here we show that the driver of
  the turbulence is the Rayleigh-Taylor (RT) instability caused by the
  interaction of neutral H atoms streaming from the ISM with the ionized
  matter in the heliosheath (HS). The drag between the neutral and ionized
  matter acts as an effective gravity which causes a RT instability to
  develop along the axis of the HS magnetic field. A density gradient
  exists perpendicular to this axis due to the confinement of the solar
  wind by the solar magnetic field. The characteristic time scale of
  the instability depends on the neutral H density in the ISM and for
  typical values the growth rate is ~ 3 years. The instability destroys
  the coherence of the heliospheric jets and magnetic reconnection ensues,
  allowing ISM material to penetrate the heliospheric tail. Signatures of
  this instability should be observable in Energetic Neutral Atom (ENA)
  maps from future missions such as IMAP (4). The turbulence driven by the
  instability is macroscopic and potentially has important implications
  for particle acceleration.

---------------------------------------------------------
Title: A Time-Dependent Split Tail Heliosphere
Authors: Powell, Erick; Opher, Merav; Toth, Gabor; Tenishev, Valeriy;
   Michael, Adam; Kornbleuth, Marc; Richardson, John
2021AGUFMSH15F2075P    Altcode:
  There is a current debate on the shape of the heliosphere. Current
  models provide different solutions to the heliotail. These
  models assume different numerical techniques as well as physical
  assumptions. Kornbleuth et al. (2021) show that both BU and Moscow
  models show collimation of the heliotail plasma by the magnetic
  field as first found by Opher et al. (2015). The BU model has the
  ISM plasma flowing between the two lobes at around 400AU downtail,
  what is known as the croissant-like heliosphere. The BU model was
  first extended to include a treatment to the neutral H in a kinetic
  fashion by Michael et al. (2021) where they show that the croissant-like
  heliotail remain. In this work, within the SHIELD project, we extend
  the work of Michael et al. (2021) with the newly updated BU model to
  investigate the effect of time dependent solar wind conditions on the
  two-lobed heliotail. The BU model in this work was a kinetic-MHD model
  that self consistently coupled an MHD treatment of ions to a kinetic
  treatment of the neutrals in a long-term solution. We have improved
  the statistics in the BU model, through implementation of a lookup
  table for the charge exchange rate and resulting source terms for the
  plasma, that is more computationally efficient and allows us to capture
  shorter time scales necessary to accurately model the evolution of the
  time-dependent heliotail. We extend the work of Michael et al. (2021)
  with the newly updated SHIELD model to investigate the effect of time
  dependent solar wind conditions on the two-lobed heliotail. We comment
  on the structure of the heliotail and the differences between long-term
  and and time-dependent solutions.

---------------------------------------------------------
Title: Modeling Galactic Cosmic Rays in the Very Local Interstellar
    Medium
Authors: Florinski, Vladimir; le Roux, Jakobus; Opher, Merav; Kleimann,
   Jens; Ghanbari, Keyvan
2021AGUFMSH31B..04F    Altcode:
  The very local interstellar medium (VLISM) presents significant
  challenges for energetic particle modeling because of the presence of
  both incompressible and compressive turbulent magnetic fluctuations (in
  the sense of the presence of the magnetic fluctuation component parallel
  to the mean field) that makes it a very distinct transport environment
  compared with the more familiar solar wind. This paper presents a
  pitch-angle dependent diffusive transport model in two-dimensional,
  compressive turbulence, and a framework for computer modeling of charged
  particles with high velocities applicable to galactic cosmic rays
  (GCRs). The model elaborates on existing weakly nonlinear theories of
  perpendicular diffusion in the limit of weak pitch-angle scattering
  combined with possibly rapid diffusive motion of the guiding center
  normal to the magnetic field. The numerical framework is based in the
  SPECTRUM (Space Plasma and Energetic Charged particle TRansport on
  Unstructured Meshes) suite of simulation codes. Two representative
  simulations are presented. The first is a high-resolution study of
  GCR transport in the VLISM region with a particular emphasis on the
  distribution of the heliopause crossing points. This model uses an
  analytic formalism for the magnetic field draping around the hsurface of
  the heliopause. The second case is a simulation of GCRs in a mesh-based
  representation of the heliosphere derived from MHD simulations converged
  to a steady state, developed for the SHIELD project. The results are
  discussed in the context of the earlier model based on the nearly
  isotropic (Parker) formalism.

---------------------------------------------------------
Title: The Development of a Split-tail Heliosphere and the Role of
Non-ideal Processes: A Comparison of the BU and Moscow Models
Authors: Kornbleuth, M.; Opher, M.; Baliukin, I.; Gkioulidou, M.;
   Richardson, J. D.; Zank, G. P.; Michael, A. T.; Tóth, G.; Tenishev,
   V.; Izmodenov, V.; Alexashov, D.; Fuselier, S.; Drake, J. F.;
   Dialynas, K.
2021ApJ...923..179K    Altcode: 2021arXiv211013962K
  Global models of the heliosphere are critical tools used in the
  interpretation of heliospheric observations. There are several
  three-dimensional magnetohydrodynamic (MHD) heliospheric models that
  rely on different strategies and assumptions. Until now only one paper
  has compared global heliosphere models, but without magnetic field
  effects. We compare the results of two different MHD models, the BU
  and Moscow models. Both models use identical boundary conditions to
  compare how different numerical approaches and physical assumptions
  contribute to the heliospheric solution. Based on the different
  numerical treatments of discontinuities, the BU model allows for the
  presence of magnetic reconnection, while the Moscow model does not. Both
  models predict collimation of the solar outflow in the heliosheath
  by the solar magnetic field and produce a split tail where the solar
  magnetic field confines the charged solar particles into distinct north
  and south columns that become lobes. In the BU model, the interstellar
  medium (ISM) flows between the two lobes at large distances due to
  MHD instabilities and reconnection. Reconnection in the BU model at
  the port flank affects the draping of the interstellar magnetic field
  in the immediate vicinity of the heliopause. Different draping in the
  models cause different ISM pressures, yielding different heliosheath
  thicknesses and boundary locations, with the largest effects at high
  latitudes. The BU model heliosheath is 15% thinner and the heliopause is
  7% more inwards at the north pole relative to the Moscow model. These
  differences in the two plasma solutions may manifest themselves in
  energetic neutral atom measurements of the heliosphere.

---------------------------------------------------------
Title: Interplanetary Hydrogen Properties as Probes into the
    Heliospheric Interface
Authors: Mayyasi, Majd; Clarke, John; Quemerais, Eric; Katushkina,
   Olga; Izmodenov, Vladislav; Provornikova, Elena; Sokol, Justyna;
   Brandt, Pontus; Galli, Andre; Opher, Merav; Kornbleuth, Marc; Linsky,
   Jeffrey; Wood, Brian
2021AGUFMSH15F2069M    Altcode:
  A NASA sponsored study conducted at John Hopkins University Applied
  Physics Lab culminated in a community-inspired heliospheric mission
  concept called the Interstellar Probe (ISP). The ISP's science goals
  include understanding our habitable astrosphere by investigating
  its interactions with the interstellar medium, and determining the
  structure, composition, and variability of its constituents. A suite
  of instruments were proposed to achieve these and other science
  objectives. The instruments include a Lyman-a spectrograph for
  velocity-resolved measurements of neutral H atoms. The capability to
  address key components of the ISP's science objectives by utilizing
  high spectral resolution Lyman-a measurements are described in this
  presentation. These findings have been submitted as a community White
  Paper to the recent Heliophysics decadal survey.

---------------------------------------------------------
Title: Signature of a Heliotail Organized by the Solar Magnetic
Field and the Role of Nonideal Processes in Modeled IBEX ENA Maps:
    A Comparison of the BU and Moscow MHD Models
Authors: Kornbleuth, M.; Opher, M.; Baliukin, I.; Dayeh, M. A.;
   Zirnstein, E.; Gkioulidou, M.; Dialynas, K.; Galli, A.; Richardson,
   J. D.; Izmodenov, V.; Zank, G. P.; Fuselier, S.
2021ApJ...921..164K    Altcode: 2021arXiv211013965K
  Energetic neutral atom (ENA) models typically require post-processing
  routines to convert the distributions of plasma and H atoms into ENA
  maps. Here we investigate how two kinetic-MHD models of the heliosphere
  (the BU and Moscow models) manifest in modeled ENA maps using the
  same prescription and how they compare with Interstellar Boundary
  Explorer (IBEX) observations. Both MHD models treat the solar wind as
  a single-ion plasma for protons, which include thermal solar wind ions,
  pick-up ions (PUIs), and electrons. Our ENA prescription partitions the
  plasma into three distinct ion populations (thermal solar wind, PUIs
  transmitted and ones energized at the termination shock) and models the
  populations with Maxwellian distributions. Both kinetic-MHD heliospheric
  models produce a heliotail with heliosheath plasma that is organized by
  the solar magnetic field into two distinct north and south columns that
  become lobes of high mass flux flowing down the heliotail; however,
  in the BU model, the ISM flows between the two lobes at distances
  in the heliotail larger than 300 au. While our prescription produces
  similar ENA maps for the two different plasma and H atom solutions at
  the IBEX-Hi energy range (0.5-6 keV), the modeled ENA maps require a
  scaling factor of ~2 to be in agreement with the data. This problem
  is present in other ENA models with the Maxwellian approximation of
  multiple ion species and indicates that either a higher neutral density
  or some acceleration of PUIs in the heliosheath is required.

---------------------------------------------------------
Title: Using Magnetic Flux Conservation to Determine Heliosheath
    Speeds
Authors: Richardson, J. D.; Cummings, A. C.; Burlaga, L. F.; Giacalone,
   J.; Opher, M.; Stone, E. C.
2021ApJ...919L..28R    Altcode:
  The heliosheath (HSH) radial speeds at Voyager 2 (V2) derived from
  the plasma instrument (PLS) and from particle instruments using the
  Compton-Getting (CG) effect are different. At V2 the CG speeds are
  more variable than the plasma speeds and decrease about 2 yr before the
  heliopause. We use magnetic flux conservation to differentiate between
  these two speed profiles at V2, comparing the magnetic flux observed
  at 1 au and in the HSH. For V2 the PLS speed profile is significantly
  more consistent with magnetic flux conservation than the CG speeds. For
  Voyager 1 (V1), we present new V<SUB>R</SUB> derivations from the
  Cosmic Ray Subsystem (CRS) using the CG method that agree reasonably
  well with those previously obtained from the low energy charged particle
  (LECP) instrument. If we use the V2 PLS speed profile to calculate the
  magnetic flux at V1, we again find much better agreement than if we use
  the V1 CG speeds. These results suggest that the radial speeds derived
  from particle anisotropy observations in the HSH are not reliable.

---------------------------------------------------------
Title: Energetic Neutral Atom Fluxes from the Heliosheath: Constraints
    from in situ Measurements and Models
Authors: Fuselier, S. A.; Galli, A.; Richardson, J. D.; Reisenfeld,
   D. B.; Zirnstein, E. J.; Heerikhuisen, J.; Dayeh, M. A.; Schwadron,
   N. A.; McComas, D. J.; Elliott, H. A.; Gomez, R. G.; Starkey, M. J.;
   Kornbleuth, M. Z.; Opher, M.; Dialynas, K.
2021ApJ...915L..26F    Altcode:
  Voyager 2 observations throughout the heliosheath from the termination
  shock to the heliopause are used to normalize and constrain model pickup
  ion (PUI) fluxes. Integrating normalized PUI fluxes along the Voyager
  2 trajectory through the heliosheath, and combining these integral
  fluxes with the energy-dependent charge-exchange cross section and
  the neutral hydrogen density, produces semi-empirical estimates of
  the energetic neutral atom (ENA) fluxes from the heliosheath. These
  estimated ENA fluxes are compared with observed ENA fluxes from the
  Interstellar Boundary Explorer (IBEX) to determine what percentage of
  the observed fluxes at each IBEX energy are from the heliosheath. These
  percentages are a maximum of ~10% for most energies and depend strongly
  on termination shock properties, plasma density, bulk plasma flow
  characteristics, the shape of the heliopause, and turbulent energy
  diffusion in the heliosheath.

---------------------------------------------------------
Title: Thank You to Our 2020 Peer Reviewers
Authors: Rajaram, Harihar; Camargo, Suzana; Cappa, Christopher; Carey,
   Rebecca; Cory, Rose; Dombard, Andrew; Donohue, Kathleen; Flesch,
   Lucy; Giannini, Alessandra; Gu, Yu; Hayes, Gavin; Hogg, Andrew; Huber,
   Christian; Ivanov, Valeriy; Jacobsen, Steven; Korte, Monika; Lu, Gang;
   Morlighem, Mathieu; Magnusdottir, Gudrun; Opher, Merav; Patricola,
   Christina; Prieto, Germán.; Qiu, Bo; Ritsema, Jeroen; Sprintall,
   Janet; Su, Hui; Sun, Daoyuan; Thornton, Joel; Trouet, Valerie; Wang,
   Kaicun; Whalen, Caitlin; White, Angelicque; Yau, Andrew
2021GeoRL..4893126R    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Hybrid Simulations of Interstellar Pickup Protons Accelerated
    at the Solar-wind Termination Shock at Multiple Locations
Authors: Giacalone, J.; Nakanotani, M.; Zank, G. P.; Kòta, J.; Opher,
   M.; Richardson, J. D.
2021ApJ...911...27G    Altcode:
  We estimate the intensity of interstellar pickup protons accelerated
  to ∼50 keV at various locations along the solar-wind termination
  shock, using two-dimensional hybrid simulations. Parameters for the
  solar wind, interstellar pickup ions (PUIs), and magnetic field just
  upstream of the termination shock at one flank of the heliosphere,
  and at the location in the downwind (or tail-ward) direction are based
  on a solar-wind/pickup-ion/turbulence model. The parameters upstream
  of the shock where Voyager 2 crossed are based on observations. The
  simulation is limited in size, and therefore cannot accurately model
  the distribution to energies much beyond ∼50 keV. This is sufficient
  to study the origin of the high-energy tail of the distribution, which
  is the low-energy portion of the anomalous cosmic-ray spectrum. We
  also extrapolate our results to other locations along the termination
  shock, such as the other flank, and the poles of the heliosphere. We
  find that the intensity of ∼10-50 keV accelerated pickup protons is
  remarkably similar at all three locations we simulated, suggesting that
  particles in this energy range are relatively uniformly distributed
  along the termination shock, and are likely quite uniform throughout
  the entire heliosheath. In addition, we find significant differences in
  the distribution in the 0.5-1 keV energy range for energetic neutral
  atoms coming from the tail region of the heliosphere compared to that
  at the nose or flank look directions. This is because the peak in the
  PUI distribution is at a higher energy there.

---------------------------------------------------------
Title: Structure of the Heliotail
Authors: Opher, Merav; Richardson, John; Krimigis, Stamatios;
   Toth, Gabor; Tenishev, Valeriy; Zank, Gary; Drake, James; Izmodenov,
   Vladislav; Fuselier, Stephen; Dialynas, Konstantinos; Baliukin, Igor;
   Dayeh, Maher A.; Zieger, Bertalan; Michael, Adam; Kornbleuth, Marc;
   Gkioulidou, Matina
2021cosp...43E.880O    Altcode:
  The canonical view of the structure of the heliosphere is that it
  has a long comet-like tail. This view is not universally accepted and
  there is vigorous debate as to whether it possesses a long comet-like
  structure, is bubble shaped, or is "croissant"-like, a debate that
  is driven by observations and modeling. Opher et al. (2015) suggest a
  heliosphere with two lobes, described as "croissant"-like. An extension
  of the single ion global 3D MHD model that treats PUIs created in
  the supersonic solar wind as a fluid separate and distinct from the
  thermal solar wind plasma yields a heliosphere that is reduced in
  size and rounder in shape (Opher et al. 2020). In contrast, Izmodenov
  et al. 2020 argue that a long/extended tail confines the plasma. One
  direct way to probe the structure of the tail is through energetic
  neutral atom (ENA) maps. ENA images of the tail by Interstellar
  Boundary Explorer (IBEX) at energies of 0.5-6keV exhibit a multi-lobe
  structure. These lobes are attributed to signatures of slow and fast
  wind within the extended heliospheric tail as part of the 11-year
  solar cycle (McComas et al. 2013; Zirnstein et al. 2017). Higher
  energy ENA observations (&gt;5.2 keV) from the Cassini spacecraft, in
  conjunction with &gt;28 keV in-situ ions from V1&amp;2/LECP (Dialynas
  et al. 2017), in contrast, support the interpretation of bubble-like
  heliosphere, with few substantial tail-like features, although there are
  interpretations otherwise (Bzowski &amp; Schwadron 2018). Regardless of
  the shape of the heliotail, there is an agreement between models that
  the solar magnetic field in the inner heliosheath (IHS) possesses a
  "slinky-like" structure (Opher et al. 2015; Pogorelov et al. 2015;
  Izmodenov et al. 2015) that helps confine the plasma in the IHS. In
  this work, as part of a recently funded project SHIELD (Solar-wind
  with Hydrogen Ion Exchange and Large-scale Dynamics), we revisit
  two different MHD models (Izmodenov et al. 2018; Opher et al. 2020)
  and investigate instabilities possibly responsible for the different
  solutions. We investigate how the different physical assumptions are
  manifested in ENA maps derived from IBEX and Cassini ENA data and
  predict what could be observed by the upcoming IMAP mission.

---------------------------------------------------------
Title: Energy Dependence of GCR Anisotropies in the VLISM
Authors: Nikoukar, Romina; Richardson, John; Roelof, Edmond; Opher,
   Merav; Krimigis, Stamatios; Hamilton, Doug C.; Hill, Matthew;
   Florinski, Vladimir; Decker, Robert; Kota, Jozsef; Giacalone, Joe;
   Dialynas, Konstantinos; Brown, Lawrence
2021cosp...43E.865N    Altcode:
  As part of the SHIELD center, in this work we report on the energy
  dependence of galactic cosmic rays (GCRs) in the very local interstellar
  medium (VLISM) as measured by the Low Energy Charged Particle (LECP)
  instruments on the Voyager 1 and 2 spacecraft (V1 and V2). The LECP
  instruments include a dual-ended telescope mechanically scanning through
  360° over eight equally-spaced angular sectors. The LECP telescope
  detects charged particles having energies from a few MeV up to GCR
  energies (&gt;= ~100 MeV). As expected, LECP measurements showed a
  dramatic increase in GCR intensities for all sectors of the &gt;=210 MeV
  LECP count rate (CH31) at the V1 heliopause crossing in 2012, however,
  since then the count rate data have demonstrated systematic episodes
  of intensity decrease for particles around 90° pitch angle. To shed
  light on the energy dependence of GCR anisotropies over a wide range
  of energies we use V1 and V2 CH31 pulse height analyzer (PHA) data,
  which allows us to divide the overall CH31 data into multiple smaller
  energy ranges, together with lower energy LECP channels. Our preliminary
  analysis shows that GCR anisotropies are present over a wide range of
  energies, and the magnitude of the anisotropies vary as a function of
  energies. The results of our analysis are used to place observational
  constraints that test existing theories or help develop new theories.

---------------------------------------------------------
Title: The Impact of Kinetic Neutrals on the Heliotail
Authors: Michael, A. T.; Opher, M.; Tóth, G.; Tenishev, V.; Drake,
   J. F.
2021ApJ...906...37M    Altcode:
  The shape of the heliosphere is thought to resemble a long, comet
  tail, however, recently it has been suggested that the heliosphere is
  tailless with a two-lobe structure. The latter study was done with
  a three-dimensional (3D) magnetohydrodynamic code, which treats the
  ionized and neutral hydrogen atoms as fluids. Previous studies that
  described the neutrals kinetically claim that this removes the two-lobe
  structure of the heliosphere. In this work, we use the newly developed
  Solar-wind with Hydrogen Ion Exchange and Large-scale Dynamics (SHIELD)
  model. SHIELD is a self-consistent kinetic-MHD model of the outer
  heliosphere that couples the MHD solution for a single plasma fluid from
  the BATS-R-US MHD code to the kinetic solution for neutral hydrogen
  atoms solved by the Adaptive Mesh Particle Simulator, a 3D, direct
  simulation Monte Carlo model that solves the Boltzmann equation. We
  use the same boundary conditions as our previous simulations using
  multi-fluid neutrals to test whether the two-lobe structure of the
  heliotail is removed with a kinetic treatment of the neutrals. Our
  results show that despite the large difference in the neutral hydrogen
  solutions, the two-lobe structure remains. These results are contrary
  to previous kinetic-MHD models. One such model maintains a perfectly
  ideal heliopause and does not allow for communication between the
  solar wind and interstellar medium. This indicates that magnetic
  reconnection or instabilities downtail play a role for the formation
  of the two-lobe structure.

---------------------------------------------------------
Title: The Structure of the Heliosphere as revealed by modeled ENA
    maps at IBEX energies
Authors: Kornbleuth, Marc; Opher, Merav; Toth, Gabor; Tenishev,
   Valeriy; Izmodenov, Vladislav; Baliukin, Igor; Michael, Adam
2021cosp...43E.896K    Altcode:
  The heliosphere is indirectly probed in all directions by energetic
  neutral atom (ENA) observations by spacecraft such as the Interstellar
  Boundary Explorer (IBEX). Energetic neutral atom (ENA) modeling is
  an important tool in understanding these ENA observations. Most MHD
  models describe the ionized components as a single ion characterized by
  a single Maxwellian distribution. This is clearly an approximation,
  a "recipe" is needed to translate the single ion to the full ion
  distribution present in the solar wind. In this work, we explore how
  different treatment of ions in ENA models and heliospheric solutions
  from two separate MHD models manifest in ENA maps. Here we use two
  different models: one from Boston University (Michael et al. 2020;
  2019) and the other from Moscow University (Izmodenov &amp; Alexashov
  2018) to probe the effect of the MHD solution in the ENA maps. The
  two MHD models treat the heliospheric boundaries differently, with
  the Moscow University model suppressing all non-ideal MHD effects
  such as reconnection and instabilities. We use same the boundary
  conditions (corresponding to solar minima) and same ISM conditions and
  investigate the differences in the modeled ENA maps, and whether IBEX
  can observe these features. The treatment of ions in the ENA model is
  also crucial. Including multiple ion species, such as using several
  pick-up ion (PUI) populations, has been shown to provide the best
  agreement between ENA models and IBEX observations. Ion propagation
  across the termination shock and downstream in the heliosheath is an
  important element in ENA production, yet there are various methods for
  modeling this propagation. We compare two separate ENA map "recipes"
  to understand the role of each population in contributing to IBEX
  observations.

---------------------------------------------------------
Title: How Pickup Ions Generate Turbulence in the Inner Heliosheath:
    A Multi-Fluid Approach
Authors: Zieger, B.; Opher, M.; Toth, G.; Florinski, V. A.
2020AGUFMSH0160017Z    Altcode:
  The solar wind in the inner heliosheath beyond the termination
  shock (TS) is a non-equilibrium collisionless plasma consisting of
  thermal solar wind ions, suprathermal pickup ions and electrons. In
  such multi-ion plasma, two fast magnetosonic wave modes exist: the
  low-frequency fast mode that propagates in the thermal ion component
  and the high-frequency fast mode that propagates in the suprathermal
  pickup ion component. Both fast modes are dispersive on fluid and
  ion scales, which results in nonlinear dispersive shock waves. We
  present high-resolution three-fluid simulations of the TS and the inner
  heliosheath up to 2.2 AU downstream of the TS. We show that downstream
  propagating nonlinear fast magnetosonic waves grow until they steepen
  into shocklets, overturn, and start to propagate backward in the frame
  of the downstream propagating wave. The counter-propagating nonlinear
  waves result in 2-D fast magnetosonic turbulence, which is driven
  by the ion-ion hybrid resonance instability. Energy is transferred
  from small scales to large scales in the inverse cascade range and
  enstrophy is transferred from large scales to small scales in the direct
  cascade range. We validate our three-fluid simulations with in-situ
  high-resolution Voyager 2 magnetic field observations in the inner
  heliosheath. Our simulations reproduce the observed magnetic turbulence
  spectrum with a spectral slope of -5/3 in frequency domain. However,
  the fluid-scale turbulence spectrum is not a Kolmogorov spectrum in
  wave number domain because Taylor's hypothesis breaks down in the
  inner heliosheath. The magnetic structure functions of the simulated
  and observed turbulence follow the Kolmogorov-Kraichnan scaling,
  which implies self-similarity.

---------------------------------------------------------
Title: Combined ∼10 eV to ∼344 MeV Particle Spectra and Pressures
    in the Heliosheath along the Voyager 2 Trajectory
Authors: Dialynas, Konstantinos; Galli, Andre; Dayeh, Maher A.;
   Cummings, Alan C.; Decker, Robert B.; Fuselier, Stephen A.; Gkioulidou,
   Matina; Roussos, Elias; Krimigis, Stamatios M.; Mitchell, Donald G.;
   Richardson, John D.; Opher, Merav
2020ApJ...905L..24D    Altcode:
  We report a unique combination of ∼10 eV to ∼344 MeV in situ
  ion measurements from the Plasma Science (PLS), Low Energy Charged
  Particle (LECP), and Cosmic Ray Subsystem (CRS) experiments on the
  Voyager 2 (V2) spacecraft, and remotely sensed ∼110 eV to ∼55
  keV energetic neutral atom (ENA) measurements from the Interstellar
  Boundary Explorer (IBEX) mission and Ion and Neutral Camera (INCA)
  on the Cassini mission. This combination is done over the time period
  from 2009 to the end of 2016, along the V2 trajectory, toward assessing
  the properties of the ion energy spectra inside the heliosheath. The
  combined energy spectra exhibit a series of softening and hardening
  breaks, providing important insights on the various ion acceleration
  processes inside the heliosheath. Ions in the &lt;6 keV energy range
  dominate the total pressure distribution inside the heliosheath but
  the ion distributions at higher energies (&gt;5.2 keV) provide a
  significant contribution to the total pressure. With the assumption
  that all ENAs (∼110 eV to 55 keV) are created by charge-exchange
  interactions inside the heliosheath, we estimate that the magnetic
  field upstream at the heliopause required to balance the pressure from
  the heliosheath in the direction of V2 is ∼0.67 nT. This number is
  consistent with the measured magnetic field at V2 from 2018 November,
  when the spacecraft entered interstellar space.

---------------------------------------------------------
Title: SIHLA , a Mission of Opportunity to L1 to Map H Lyman Alpha
    Emissions from the Heliopause, the Interplanetary Medium, the Earth's
    Geocorona and Comets
Authors: Paxton, L. J.; Provornikova, E.; Roelof, E. C.; Quemerais,
   E.; Izmodenov, V.; Katushkina, O. A.; Mierkiewicz, E. J.; Baliukin, I.;
   Gruntman, M.; Taguchi, M.; Pryor, W. R.; Mayyasi, M.; Koutroumpa, D.;
   Opher, M.; Lallement, R.; Barjatya, A.; Vervack, R. J., Jr.; Lisse,
   C. M.; Schaefer, R. K.; Barnes, R. J.; Wood, B. E.
2020AGUFMSH040..03P    Altcode:
  SIHLA (Spatial/Spectral Imaging of Heliospheric Lyman Alpha pronounced
  as `Scylla' [e.g. Homer, Odyssey, ~675-725 BCE] investigates fundamental
  physical processes that determine the interaction of the Sun with the
  interstellar medium (ISM); the Sun with the Earth; and the Sun with
  comets and their subsequent evolution. To accomplish these goals,
  SIHLA studies the shape of the heliosphere and maps the solar wind in
  3D; characterizes changes in Earth's extended upper atmosphere (the
  hydrogen `geocorona'); discovers new comets and tracks the composition
  changes of new and known ones as they pass near the Sun. <P />SIHLA
  is a NASA Mission of Opportunity that has just completed its Phase A
  study (the Concept Study Report or CSR). At the time of the writing of
  this abstract NASA has not decided whether to fly this small satellite
  mission or its competitor (GLIDE: PI Prof. Lara Waldrop). SIHLA observes
  the ion-neutral interactions of hydrogen, the universe's most abundant
  element, from the edge of the solar system to the Earth, to understand
  the fundamental properties that shaped our own home planet Earth and
  the heliosphere. From its L1 vantage point, well outside the Earth's
  obscuring geocoronal hydrogen cloud, SIHLA maps the entire sky using
  a flight-proven, compact, far ultraviolet (FUV) hyperspectral imager
  with a Hydrogen Absorption Cell (HAC). The hyperspectral scanning
  imaging spectrograph (SIS) in combination with the spacecraft roll,
  creates 4 maps &gt;87% of the sky each day, at essentially monochromatic
  lines over the entire FUV band (115 to 180nm) at every point in the
  scan. During half of these daily sky maps, the hydrogen absorption
  cell (HAC) provides a 0.001nm notch rejection filter for the H Lyman a
  . Using the HAC, SIHLA builds up the lineshape profile of the H Lyman
  a emissions over the course of a year. SIHLA's SIS/HAC combination
  enables us to image the result of the ion-neutral interactions in the
  heliosheath, 100 AU away, in the lowest energy, highest density, part
  of the neutral atom spectrum - H atoms with energies below 10eV. <P
  />The novel aspects of SIHLA are the scope of the science done within
  a MoO budget. The SIHLA projected costs were below the $75M cap with a
  31.3% reserve for Phase B-D. The re-purposing of a spectrographic that
  was part of the DMSP SSUSI line (a copy was flown and NASA TIMED/GUVI
  and as NASA NEAR/NIS). Risk is extremely low in this Class-D mission
  with all major elements at least at TRL6 at this time. <P />SIHLA
  has a high potential for discovery. We expect that we will 1) First
  detection of the hot H atoms produced directly from the ion-neutral
  interactions at the heliopause; 2) First detection of structures in
  Interplanetary Medium H emission, 3) First detection of response of the
  Earth's extended (out to lunar orbit) geocorona to solar/geomagnetic
  drivers, 4) New UV-bright comets as they enter the inner solar system.

---------------------------------------------------------
Title: The Effect of Changing Solar Magnetic Field Intensity on
    ENA Maps
Authors: Kornbleuth, M. Z.; Opher, M.; Michael, A. T.; Sokol, J. M.;
   Toth, G.; Tenishev, V.
2020AGUFMSH0230008K    Altcode:
  Opher et al. (2015) showed that the solar magnetic field can confine and
  collimate the solar wind plasma in the heliosheath. IBEX observations
  of the heliotail have shown the presence of two high latitude
  lobes of enhanced ENA flux in the heliotail at high energies (&gt;2
  keV). Numerous studies have investigated how the latitudinal variation
  of the solar wind during the solar cycle affects the latitudinal profile
  of ENAs in the heliotail. Kornbleuth et al. (2020) showed that while
  the solar wind profile does contribute to the high latitude lobes
  observed by IBEX in the heliotail, the solar magnetic field plays a
  significant role as well. In this work we use steady state MHD solutions
  corresponding to solar wind conditions from particular years to isolate
  how conditions corresponding to different periods of the solar cycle
  influence ENA maps. We find the variations in the intensity of the
  solar magnetic field play an important role in not only influencing
  observations of the heliotail, but also in affecting the thickness
  of the heliosheath in the direction of the nose. The variations not
  only affect the ENA intensity observed in the high latitude tail, but
  also the size and location of the high latitude lobes. Additionally,
  as noted by previous studies, we find the changes in the solar wind
  dynamic pressure influence the observed ENA flux and that asymmetries
  in the dynamic pressure can be discerned from ENA maps.

---------------------------------------------------------
Title: Heliospheric Ly α Absorption in a Split Tail Heliosphere
Authors: Powell, E.; Opher, M.; Michael, A. T.; Kornbleuth, M. Z.;
   Wood, B. E.; Izmodenov, V.; Toth, G.; Tenishev, V.; Richardson, J. D.
2020AGUFMSH0170013P    Altcode:
  Neutral hydrogen in the hydrogen wall and heliosheath absorb wavelengths
  of light near Ly α from nearby stars. Heliospheric models are essential
  to understand these observations since the observations are an indirect
  method of probing the the heliosphere. Opher et al. (2015) suggested
  that the solar magnetic field can collimate the solar wind plasma,
  resulting in a heliosphere with a split tail. We compare the Ly α
  predictions made by multi-fluid kinetic-MHD models of Opher et al. 2020,
  Michael et al. 2020 that present a "Croissant-like" (split tail)
  shape with long tail models used in Izmodenov et al. 2018. Previous
  studies have shown that the interstellar magnetic field can affect the
  distribution of neutral hydrogen in the hydrogen wall just outside
  the heliosphere. In this study our models use a grid that extends
  1500 AU downwind and vary the Interstellar magnetic field strength
  and direction. The split tail model successfully reproduce the LY α
  profiles in upwind and sidewind line of sights and have good agreement
  in downwind line of sights. We comment on the differences between
  the two MHD models and which directions can be more sensitive to the
  heliospheric shape as well from the interstellar magnetic field.

---------------------------------------------------------
Title: Structure of the Heliosphere and Heliotail from different
    MHD models as Probed by ENA maps
Authors: Opher, M.
2020AGUFMSH027..04O    Altcode:
  The canonical view of the shape of the heliosphere until recently was
  that it has a long comet-like tail. This view is being challenged and
  it is now debated whether the heliosphere has a long comet-like shape,
  has a bubble shape, or has a "croissant"-like shape and these options
  are being investigated prompted through observations and modeling. <P
  />One direct way to probe the structure of the heliotail is through
  energetic neutral atom (ENA) maps. These ENAs have been observed by
  the Interstellar Boundary Explorer (IBEX) at energies of 0.5-6 keV
  by the IBEX-Hi instrument and show a multi-lobe structure. These
  lobes were interpreted as signatures of slow and fast wind within a
  long heliospheric tail as part of the 11-year solar cycle (McComas
  et al. 2013; Zirnstein et al. 2017). In contrast, higher energy ENAs
  observed by CASSINI suggest that the heliosphere is round (Dialynas
  et al. 2017). <P />Opher et al. (2015) suggest that the heliosphere
  has two lobes (is "croissant"-like). They extend their global 3D
  MHD model to treat thermal plasma and pickup ions as separate fluids
  and show that this treatment deflates the heliosphere leading to a
  smaller and rounder shape (Opher et al. 2020). Izmodenov et al. 2020
  argue for confinement but in a long extended tail. <P />Regardless of
  the shape of the heliotail, the models agree that the solar magnetic
  field in the inner heliosheath has a "slinky" structure (Opher et
  al. 2015; Pogorelov et al. 2015; Izmodenov et al. 2015) that confines
  the heliosphere plasma. <P />In this work, as part of the recently
  funded SHIELD (Solar-wind with Hydrogen Ion Exchange and Large-scale
  Dynamics ) center which is now in Phase I, we revisit two different
  MHD models (Izmodenov et al. 2018; Opher et al. 2020) and explore how
  the different physical assumptions manifest in ENA maps. We comment
  as well on how the conditions ahead of the heliosphere in the VLISM
  are different in the two models.

---------------------------------------------------------
Title: Dispersive Fast Magnetosonic Waves and Shock-Driven
    Compressible Turbulence in the Inner Heliosheath
Authors: Zieger, Bertalan; Opher, Merav; Tóth, Gábor; Florinski,
   Vladimir
2020JGRA..12528393Z    Altcode:
  The solar wind in the inner heliosheath beyond the termination
  shock (TS) is a nonequilibrium collisionless plasma consisting of
  thermal solar wind ions, suprathermal pickup ions, and electrons. In
  such multi-ion plasma, two fast magnetosonic wave modes exist,
  the low-frequency fast mode and the high-frequency fast mode. Both
  fast modes are dispersive on fluid and ion scales, which results
  in nonlinear dispersive shock waves. We present high-resolution
  three-fluid simulations of the TS and the inner heliosheath up to a few
  astronomical units (AU) downstream of the TS. We show that downstream
  propagating nonlinear fast magnetosonic waves grow until they steepen
  into shocklets, overturn, and start to propagate backward in the frame
  of the downstream propagating wave. The counterpropagating nonlinear
  waves result in 2-D fast magnetosonic turbulence, which is driven
  by the ion-ion hybrid resonance instability. Energy is transferred
  from small scales to large scales in the inverse cascade range, and
  enstrophy is transferred from large scales to small scales in the
  direct cascade range. We validate our three-fluid simulations with in
  situ high-resolution Voyager 2 magnetic field observations in the inner
  heliosheath. Our simulations reproduce the observed magnetic turbulence
  spectrum with a spectral slope of -5/3 in frequency domain. However,
  the fluid-scale turbulence spectrum is not a Kolmogorov spectrum in
  wave number domain because Taylor's hypothesis breaks down in the
  inner heliosheath. The magnetic structure functions of the simulated
  and observed turbulence follow the Kolmogorov-Kraichnan scaling,
  which implies self-similarity.

---------------------------------------------------------
Title: The Downwind Solar Wind: Model Comparison with Pioneer 10
    Observations
Authors: Nakanotani, M.; Zank, G. P.; Adhikari, L.; Zhao, L. -L.;
   Giacalone, J.; Opher, M.; Richardson, J. D.
2020ApJ...901L..23N    Altcode:
  The solar wind in the upwind region has been well modeled using a
  pickup ion (PUI) mediated MHD model (Zank et al.). It suggests that
  PUIs have an important role in heating the solar wind in the outer
  heliosphere. However, the solar wind in the downwind region is not as
  well understood. Here, we compare the Zank et al. model with Pioneer
  10 observations, which allows us to investigate the downwind solar
  wind out to 60 au. We use a model in which the hydrogen temperature
  is finite to obtain a proper hydrogen number density distribution in
  the downwind region and incorporate it into the model. Our results
  explain Pioneer 10 observations well and indicate that the heating
  due to PUIs is less effective than in the upwind region since the
  density of PUIs in the downwind region is less than the upwind PUIs
  density. We also derive parameters at several possible locations of
  the downwind termination shock.

---------------------------------------------------------
Title: Thank You to Our 2019 Peer Reviewers
Authors: Rajaram, Harihar; Camargo, Suzana; Carey, Rebecca; Corey, Rose
   M.; Dombard, Andrew J.; Donohue, Kathleen A.; Flesch, Lucy; Giannini,
   Alessandra; Hayes, Gavin; Huber, Christian; Hogg, Andy M.; Ivanov,
   Valeriy; Jacobsen, Steven D.; Korte, Monika; Lu, Gang; Morlighem,
   Mathieu; Magnusdottir, Gudrun; Opher, Merav; Patricola, Christina M.;
   Ritsema, Jeroen; Sprintall, Janet; Su, Hui; Thornton, Joel A.; Trouet,
   Valerie; Wang, Kaicun; White, Angelicque E.; Yau, Andrew
2020GeoRL..4788048R    Altcode:
  On behalf of the journal, AGU, and the scientific community, the editors
  would like to sincerely thank those who reviewed the manuscripts for
  Geophysical Research Letters in 2019. The hours reading and commenting
  on manuscripts not only improve the manuscripts but also increase
  the scientific rigor of future research in the field. We particularly
  appreciate the timely reviews in light of the demands imposed by the
  rapid review process at Geophysical Research Letters. With the revival
  of the "major revisions" decisions, we appreciate the reviewers'
  efforts on multiple versions of some manuscripts. With the advent of
  AGU's data policy, many reviewers have helped immensely to evaluate the
  accessibility and availability of data associated with the papers they
  have reviewed, and many have provided insightful comments that helped
  to improve the data presentation and quality. We greatly appreciate
  the assistance of the reviewers in advancing open science, which
  is a key objective of AGU's data policy. Many of those listed below
  went beyond and reviewed three or more manuscripts for our journal,
  and those are indicated in italics.

---------------------------------------------------------
Title: Major Scientific Challenges and Opportunities in Understanding
    Magnetic Reconnection and Related Explosive Phenomena in Solar and
    Heliospheric Plasmas
Authors: Ji, H.; Karpen, J.; Alt, A.; Antiochos, S.; Baalrud, S.;
   Bale, S.; Bellan, P. M.; Begelman, M.; Beresnyak, A.; Bhattacharjee,
   A.; Blackman, E. G.; Brennan, D.; Brown, M.; Buechner, J.; Burch, J.;
   Cassak, P.; Chen, B.; Chen, L. -J.; Chen, Y.; Chien, A.; Comisso,
   L.; Craig, D.; Dahlin, J.; Daughton, W.; DeLuca, E.; Dong, C. F.;
   Dorfman, S.; Drake, J.; Ebrahimi, F.; Egedal, J.; Ergun, R.; Eyink,
   G.; Fan, Y.; Fiksel, G.; Forest, C.; Fox, W.; Froula, D.; Fujimoto,
   K.; Gao, L.; Genestreti, K.; Gibson, S.; Goldstein, M.; Guo, F.; Hare,
   J.; Hesse, M.; Hoshino, M.; Hu, Q.; Huang, Y. -M.; Jara-Almonte, J.;
   Karimabadi, H.; Klimchuk, J.; Kunz, M.; Kusano, K.; Lazarian, A.; Le,
   A.; Lebedev, S.; Li, H.; Li, X.; Lin, Y.; Linton, M.; Liu, Y. -H.;
   Liu, W.; Longcope, D.; Loureiro, N.; Lu, Q. -M.; Ma, Z-W.; Matthaeus,
   W. H.; Meyerhofer, D.; Mozer, F.; Munsat, T.; Murphy, N. A.; Nilson,
   P.; Ono, Y.; Opher, M.; Park, H.; Parker, S.; Petropoulou, M.; Phan,
   T.; Prager, S.; Rempel, M.; Ren, C.; Ren, Y.; Rosner, R.; Roytershteyn,
   V.; Sarff, J.; Savcheva, A.; Schaffner, D.; Schoeffier, K.; Scime, E.;
   Shay, M.; Sironi, L.; Sitnov, M.; Stanier, A.; Swisdak, M.; TenBarge,
   J.; Tharp, T.; Uzdensky, D.; Vaivads, A.; Velli, M.; Vishniac, E.;
   Wang, H.; Werner, G.; Xiao, C.; Yamada, M.; Yokoyama, T.; Yoo, J.;
   Zenitani, S.; Zweibel, E.
2020arXiv200908779J    Altcode:
  Magnetic reconnection underlies many explosive phenomena in the
  heliosphere and in laboratory plasmas. The new research capabilities in
  theory/simulations, observations, and laboratory experiments provide the
  opportunity to solve the grand scientific challenges summarized in this
  whitepaper. Success will require enhanced and sustained investments
  from relevant funding agencies, increased interagency/international
  partnerships, and close collaborations of the solar, heliospheric,
  and laboratory plasma communities. These investments will deliver
  transformative progress in understanding magnetic reconnection and
  related explosive phenomena including space weather events.

---------------------------------------------------------
Title: Voyager 2 Observations Near the Heliopause
Authors: Richardson, John D.; Belcher, John W.; Burlaga, Leonard F.;
   Cummings, Alan C.; Decker, Robert B.; Opher, Merav; Stone, Edward C.
2020JPhCS1620a2016R    Altcode:
  This paper discusses plasma characteristics in the heliosheath
  region before the heliopause (HP), at the HP, and in the very local
  interstellar medium (VLISM). The Voyager 2 (V2) HP was a sharp boundary
  where the radial plasma currents went to background levels. The radial
  flow speeds derived from 53-85 keV (V1) and 28-43 keV (V2) ion data
  decreased about 2 years (8 AU) before the HP at V1 and V2. A speed
  decrease was not observed by the V2 plasma instrument until 160 days
  (1.5 AU) before the HP crossing when V2 entered the plasma boundary
  layer where the plasma density and 28-43 keV ion intensity increased. We
  determine the HP orientation based on the plasma flow and magnetic field
  data and show these observations are consistent with models predicting
  a blunt HP. Variations are observed in the currents observed in the
  VLISM; roll data from this region clearly show the plasma instrument
  observes the interstellar plasma and may be consistent with larger
  than expected VLISM temperatures near the HP.

---------------------------------------------------------
Title: The Confinement of the Heliosheath Plasma by the Solar Magnetic
    Field as Revealed by Energetic Neutral Atom Simulations
Authors: Kornbleuth, M.; Opher, M.; Michael, A. T.; Sokół, J. M.;
   Tóth, G.; Tenishev, V.; Drake, J. F.
2020ApJ...895L..26K    Altcode: 2020arXiv200506643K
  Traditionally, the solar magnetic field has been considered to have
  a negligible effect in the outer regions of the heliosphere. Recent
  works have shown that the solar magnetic field may play a crucial role
  in collimating the plasma in the heliosheath. Interstellar Boundary
  Explorer (IBEX) observations of the heliotail indicated a latitudinal
  structure varying with energy in the energetic neutral atom (ENA)
  fluxes. At energies ∼1 keV, the ENA fluxes show an enhancement at
  low latitudes and a deficit of ENAs near the poles. At energies &gt;2.7
  keV, ENA fluxes had a deficit within low latitudes, and lobes of higher
  ENA flux near the poles. This ENA structure was initially interpreted
  to be a result of the latitudinal profile of the solar wind during
  solar minimum. We extend the work of Kornbleuth et al. by using solar
  minimum-like conditions and the recently developed Solar-wind with
  Hydrogen Ion Exchange and Large-scale Dynamics (SHIELD) model. The
  SHIELD model couples the magnetohydrodynamic plasma solution with
  a kinetic description of neutral hydrogen. We show that while the
  latitudinal profile of the solar wind during solar minimum contributes
  to the lobes in ENA maps, the collimation by the solar magnetic
  field is important in creating and shaping the two high-latitude
  lobes of enhanced ENA flux observed by IBEX. This is the first work
  to explore the effect of the changing solar magnetic field strength
  on ENA maps. Our findings suggest that IBEX is providing the first
  observational evidence of the collimation of the heliosheath plasma
  by the solar magnetic field.

---------------------------------------------------------
Title: Publisher Correction: A small and round heliosphere suggested
    by magnetohydrodynamic modelling of pick-up ions
Authors: Opher, Merav; Loeb, Abraham; Drake, James; Toth, Gabor
2020NatAs...4..719O    Altcode: 2020NatAs.tmp...96O
  An amendment to this paper has been published and can be accessed via
  a link at the top of the paper.

---------------------------------------------------------
Title: The Solar-wind with Hydrogen Ion Exchange and Large-scale
Dynamics (SHIELD) model: A Self-Consistent Kinetic-MHD Model of the
    Outer Heliosphere
Authors: Michael, Adam T.; Opher, Merav; Toth, Gabor; Tenishev,
   Valeriy; Borovikov, Dmitry
2020arXiv200401152M    Altcode:
  Neutral hydrogen has been shown to greatly impact the plasma flow in
  the heliopshere and the location of the heliospheric boundaries. We
  present the results of the Solar-wind with Hydrogen Ion Exchange
  and Large-scale Dynamics (SHIELD) model, a new, self-consistent,
  kinetic-MHD model of the outer heliosphere within the Space Weather
  Modeling Framework. The charge-exchange mean free path is on order
  of the size of the heliosphere; therefore, the neutral atoms cannot
  be described as a fluid. The SHIELD model couples the MHD solution
  for a single plasma fluid to the kinetic solution from for neutral
  hydrogen atoms streaming through the system. The kinetic code is based
  on the Adaptive Mesh Particle Simulator (AMPS), a Monte Carlo method for
  solving the Boltzmann equation. The SHIELD model accurately predicts the
  increased filtration of interstellar neutrals into the heliosphere. In
  order to verify the correct implementation within the model, we compare
  the results of the SHIELD model to other, well-established kinetic-MHD
  models. The SHIELD model matches the neutral hydrogen solution of these
  studies as well as the shift in all heliospheric boundaries closer
  to the Sun in comparison the the multi-fluid treatment of the neutral
  hydrogen atoms. Overall the SHIELD model shows excellent agreement to
  these models and is a significant improvement to the fluid treatment
  of interstellar hydrogen.

---------------------------------------------------------
Title: A small and round heliosphere suggested by magnetohydrodynamic
    modelling of pick-up ions
Authors: Opher, Merav; Loeb, Abraham; Drake, James; Toth, Gabor
2020NatAs...4..675O    Altcode: 2020NatAs.tmp...55O; 2020NatAs.tmp...90O
  As the Sun moves through the surrounding partially ionized medium,
  neutral hydrogen atoms penetrate the heliosphere, and through charge
  exchange with the supersonic solar wind, create a population of hot
  pick-up ions (PUIs). Until recently, the consensus was that the shape
  of the heliosphere is comet-like. The termination shock crossing by
  Voyager 2 demonstrated that the heliosheath (the region of shocked
  solar wind) pressure is dominated by PUIs; however, the impact of
  the PUIs on the global structure of the heliosphere has not been
  explored. Here we use a novel magnetohydrodynamic model that treats
  the PUIs as a separate fluid from the thermal component of the solar
  wind. The depletion of PUIs, due to charge exchange with the neutral
  hydrogen atoms of the interstellar medium in the heliosheath, cools the
  heliosphere, `deflating' it and leading to a narrower heliosheath and
  a smaller and rounder shape, confirming the shape suggested by Cassini
  observations. The new model reproduces both the properties of the PUIs,
  based on the New Horizons observations, and the solar wind ions, based
  on the Voyager 2 spacecraft observations as well as the solar-like
  magnetic field data outside the heliosphere at Voyager 1 and Voyager 2.

---------------------------------------------------------
Title: Major Scientific Challenges and Opportunities in Understanding
    Magnetic Reconnection and Related Explosive Phenomena throughout
    the Universe
Authors: Ji, H.; Alt, A.; Antiochos, S.; Baalrud, S.; Bale, S.;
   Bellan, P. M.; Begelman, M.; Beresnyak, A.; Blackman, E. G.; Brennan,
   D.; Brown, M.; Buechner, J.; Burch, J.; Cassak, P.; Chen, L. -J.;
   Chen, Y.; Chien, A.; Craig, D.; Dahlin, J.; Daughton, W.; DeLuca, E.;
   Dong, C. F.; Dorfman, S.; Drake, J.; Ebrahimi, F.; Egedal, J.; Ergun,
   R.; Eyink, G.; Fan, Y.; Fiksel, G.; Forest, C.; Fox, W.; Froula, D.;
   Fujimoto, K.; Gao, L.; Genestreti, K.; Gibson, S.; Goldstein, M.; Guo,
   F.; Hesse, M.; Hoshino, M.; Hu, Q.; Huang, Y. -M.; Jara-Almonte, J.;
   Karimabadi, H.; Klimchuk, J.; Kunz, M.; Kusano, K.; Lazarian, A.;
   Le, A.; Li, H.; Li, X.; Lin, Y.; Linton, M.; Liu, Y. -H.; Liu, W.;
   Longcope, D.; Loureiro, N.; Lu, Q. -M.; Ma, Z-W.; Matthaeus, W. H.;
   Meyerhofer, D.; Mozer, F.; Munsat, T.; Murphy, N. A.; Nilson, P.;
   Ono, Y.; Opher, M.; Park, H.; Parker, S.; Petropoulou, M.; Phan, T.;
   Prager, S.; Rempel, M.; Ren, C.; Ren, Y.; Rosner, R.; Roytershteyn,
   V.; Sarff, J.; Savcheva, A.; Schaffner, D.; Schoeffier, K.; Scime, E.;
   Shay, M.; Sitnov, M.; Stanier, A.; TenBarge, J.; Tharp, T.; Uzdensky,
   D.; Vaivads, A.; Velli, M.; Vishniac, E.; Wang, H.; Werner, G.; Xiao,
   C.; Yamada, M.; Yokoyama, T.; Yoo, J.; Zenitani, S.; Zweibel, E.
2020arXiv200400079J    Altcode:
  This white paper summarizes major scientific challenges and
  opportunities in understanding magnetic reconnection and related
  explosive phenomena as a fundamental plasma process.

---------------------------------------------------------
Title: CME deflections due to magnetic forces from the Sun and
    Kepler-63
Authors: Menezes, F.; Netto, Y.; Kay, C.; Opher, M.; Valio, A.
2020IAUS..354..421M    Altcode:
  The stellar magnetic field is the driver of activity in the star and
  can trigger energetic flares, CMEs and ionized wind. These phenomena,
  specially CMEs, may have an important impact on the magnetosphere and
  atmosphere of the orbiting planets. To predict whether a CME will impact
  a planet, the effects of the background on the CME's trajectory must
  be taken into account. We used the MHD code ForeCAT - a model for CME
  deflection due to magnetic forces - to perform numerical simulations of
  CMEs being launched from both the Sun and Kepler-63, which is a young,
  solar-like star with high activity. Comparing results from Kepler-63
  and the Sun gives us a panorama of the distinct activity level and
  star-planet interactions of these systems due to the difference of
  stellar ages and star-planet distances.

---------------------------------------------------------
Title: Energetic Neutral Atom Maps from a Kinetic-MHD Description
    of the "Croissant-like" Heliosphere
Authors: Kornbleuth, M. Z.; Opher, M.; Michael, A.; Sokol, J. M.
2019AGUFMSH51C3335K    Altcode:
  Opher et al. (2015) suggested that due to the collimation of the solar
  wind plasma by the solar magnetic field, two high latitude lobes would
  emerge, resulting in a shortened heliotail with a "croissant-like"
  shape. Other works hypothesized that using a kinetic treatment of
  neutrals in modeling the heliosphere would lead to the disappearance
  of this "croissant-like" shape. Recently, Michael et al. (2019) showed
  that using the Solar-wind with Hydrogen Ion Exchange and Large-scale
  Dynamics (SHIELD) model, which is a 3D MHD model coupled with a
  kinetic description of neutrals, the "croissant-like" structure
  of the heliosphere persists. The Interstellar Boundary Explorer
  (IBEX) is probing the heliosphere by using energetic neutral atoms
  (ENAs). McComas et al. (2013) and Schwadron et al. (2014) showed two
  high latitude lobes of increased ENA flux at the highest IBEX energies,
  with a deficit of ENA flux in the low latitude tail. This observed
  structure was suggested to be the result of the latitudinal variation
  of the solar wind. Zirnstein et al. (2017) showed that using a time
  dependent model of the heliosphere, the ENA structure observed by IBEX
  could be reasonably replicated. Kornbleuth et al. (2018) showed that
  the collimation of the solar wind plasma seen by Opher et al. (2015)
  could also lead to the emergence of high latitude lobes of increased
  ENA flux in the absence of a varying solar wind structure. In this
  work, we use the SHIELD model of the heliosphere to investigate the
  underlying effect of solar wind collimation on ENA maps. We present
  maps from a case where no collimation is present (by neglecting solar
  magnetic field) and compare with a case where collimation is present. In
  both cases we include the solar wind latitudinal variations as in
  solar minimum in 2008 using a model developed by Sokol et al (2015),
  which is based on the interplanetary scintillation observations of
  the solar wind structure (Tokumaru et al 2012). We find that while
  a latitudinally-varying solar wind structure can replicate IBEX
  observations in the absence of solar wind collimation, the inclusion
  of collimation causes an enhancement of the high latitude lobes at
  the highest IBEX energies. As the solar magnetic field strengthens or
  weakens over the course of a solar cycle, the varying strength of the
  collimation should be observable in IBEX ENA observations.

---------------------------------------------------------
Title: Preferential Ion Heating and Particle Acceleration Downstream
    of Dispersive Shock Waves in Collisionless Multi-Ion Plasma
Authors: Zieger, B.; Toth, G.; Opher, M.
2019AGUFMSH23B3396Z    Altcode:
  We briefly review the theory of dispersive shock waves in collisionless
  multi-ion plasma. In such plasma, two (or more) fast magnetosonic wave
  modes exist: the high-frequency fast mode that propagates in the ion
  component with the higher thermal speed and the low-frequency fast mode
  that propagates in the ion component with the lower thermal speed [Toida
  and Aota, 2013; Zieger et al., 2015]. Both fast modes are dispersive
  on fluid and ion scales, which results in nonlinear dispersive shock
  waves. A negative dispersive wave mode produces a trailing wave
  train downstream of the shock, while a positive dispersive wave mode
  produces a precursor wave train upstream of the shock [Biskamp, 1973;
  Hoefer, 2014]. Here we present high-resolution three-fluid simulations
  of dispersive shock waves in two-ion-species plasma. We show that
  downstream propagating nonlinear magnetosonic waves grow until they
  steepen into shocklets (thin current sheets), overturn, and start to
  propagate backward in the frame of the downstream propagating wave, as
  predicted by theory [McKenzie et al., 1993; Dubinin et al, 2006]. The
  counter-propagating nonlinear waves result in fast magnetosonic
  turbulence far downstream of the shock. Interestingly, energy is
  transferred from small scales to large scales (inverse energy cascade)
  in the high-frequency fast mode, and from large scales to small scales
  (direct energy cascade) in the low-frequency fast mode as the turbulence
  develops in time. We show that the ion species with the lower thermal
  speed is preferentially heated by the turbulence. Forward shocklets
  can efficiently accelerate both ions and electrons to high energies
  through the shock drift acceleration mechanism. We can conclude that
  fast magnetosonic turbulence in collisionless multi-ion plasma will move
  the plasma towards a state where the thermal speeds of different ion
  species are comparable. Our theoretical and numerical simulation results
  could help to explain the observed preferential heating of heavy ions
  in the solar corona, the acceleration of energetic particles downstream
  of interpanetary shocks in the multi-ion solar wind, the non-adiabatic
  cooling of solar wind ions and pickup ions in the outer heliosphere,
  and the unfolding of the anomalous cosmic ray energy spectra in the
  heliosheath, downstream of the termination shock.

---------------------------------------------------------
Title: The Two-Lobe Structure of the Heliosphere Persists in the
    SHIELD Model, a K-MHD Model of the Outer Heliosphere
Authors: Michael, A.; Opher, M.; Toth, G.; Tenishev, V.; Borovikov, D.
2019AGUFMSH51B..07M    Altcode:
  The canonical view of the shape of the heliosphere resembles a long
  comet tail, however, our research group at BU, led by Dr. Merav
  Opher, has suggested that the heliosphere is tailless with a
  two-lobe structure. This study was done with a state-of-the-art 3D
  magnetohydrodynamic (MHD) code that treats the ionized and neutral
  hydrogen atoms as fluids. Previous studies that have described the
  neutrals kinetically have claimed that this removes the two-lobe
  structure of the heliosphere. In this work, we will use the newly
  developed Solar-wind with Hydrogen Ion Exchange and Large-scale
  Dynamics (SHIELD) model, a self-consistent kinetic-MHD model of the
  outer heliosphere. The SHIELD model couples the Outer Heliosphere
  (OH) and Particle Tracker (PT) components within the Space Weather
  Modeling Framework (SWMF). The OH component utilizes the Block-Adaptive
  Tree Solarwind Roe-type Upwind Scheme (BATS-R-US) MHD code, a highly
  parallel, 3D, and block-adaptive solver. The PT component is based
  on the Adaptive Mesh Particle Simulator (AMPS) model, a 3D, direct
  simulation Monte Carlo model that solves the Boltzmann equation to
  model the neutral distribution function throughout the domain. The
  SHIELD model couples the MHD solution for a single plasma fluid to the
  kinetic solution from for neutral hydrogen atoms streaming through the
  system. We use the same boundary conditions as Opher et al. (2015), the
  seminal work on the two-lobe structure, within the SHIELD model to test
  whether the two-lobe structure of the heliotail is removed. Our results
  show that despite the large difference in the neutral solution between
  the fluid and kinetic treatment of the neutral hydrogen, the two-lobe
  structure remains even when the neutral hydrogen atoms are modeled
  kinetically. These results are contrary to Izmodenov et al (2018),
  whose model maintains a perfectly ideal heliopause and does not allow
  for communication between the solar wind and interstellar medium . This
  indicates that magnetic reconnection downtail and/or instabilities
  play a crucial role for the formation of the two-lobe structure.

---------------------------------------------------------
Title: The Structure of the Heliotail as probed by a Kinetic-MHD,
    a Multi-Ion Description of the Heliosphere and Energetic Neutral Maps
Authors: Opher, M.; Michael, A.; Kornbleuth, M. Z.; Drake, J. F.;
   Loeb, A.; Toth, G.
2019AGUFMSH53A..04O    Altcode:
  A critical question regarding the heliosphere is its veryshape and the
  structure of the heliotail (whether it has a long comet-like shape,
  is bubble shaped, or "croissant"-like), prompted by observations
  and modeling (Opher et al. 2015; Pogorelov et al. 2015; Izmodenov
  &amp; Alexashov 2015; Dialynas et al. 2017; Schwadron &amp; Bzowski
  2018). Opher et al. (2015) show that the magnetic tension of the solar
  magnetic field organizes the solar wind in the heliosheath into two
  jet-like structures, giving the heliosphere a "croissant"-like shape
  where the distance to the heliopause downtail is almost the same as
  that towards the nose. <P />There have been arguments that with a
  kinetic treatment of the neutral H, the heliotail extends to large
  distances (Izmodenov et al. 2018; Pogorelov et al. 2015). We recently
  developed the Solar-wind with Hydrogen Ion Exchange and Large-scale
  Dynamics (SHIELD) model, a self-consistent kinetic-MHD model of the
  outer heliosphere within the SWMF framework (Toth et al. 2012). The
  SHIELD model couples the MHD solution for a single plasma fluid to
  the kinetic solution for neutral hydrogen atoms streaming through
  the system. Our results show that even when the neutral H atoms
  are treated kinetically, the two-lobe structure remains (Michael et
  al. 2019). Their results indicate that magnetic reconnection downtail
  and/or instabilities play a crucial role in the formation of the
  two-lobe structure. We will present globally distributed flux (GDF)
  ENA maps from the SHIELD model, including a latitudinal variation of
  the solar wind corresponding to the conditions in the year 2008 using
  solar wind data from Sokol et al. (2015). The GDF ENA maps replicate
  the IBEX observations for solar minima conditions. <P />We have also
  recently extended our global MHD model (Opher et al. 2019) to treat the
  pick-up ions (PUIs) created in the supersonic solar wind as a separate
  fluid from the thermal component of the solar wind. The PUIs charge
  exchange with the cold neutral H atoms of the ISM in the heliosheath
  and are quickly depleted. The depletion of PUIs cools the heliosphere
  downstream of the TS, "deflating" it and leading to a narrower HS and a
  smaller and rounder shape. With this model, we reproduce the IBEX ENA
  observations along Voyager 2, as well the magnetic field observations
  at Voyager 1 and 2 ahead of the heliosphere.

---------------------------------------------------------
Title: Thank You to Our 2018 Peer Reviewers
Authors: Rajaram, Harihar; Diffenbaugh, Noah; Camargo, Suzana;
   Cardenas, M. Bayani; Carey, Rebecca; Cobb, Kim; Cory, Rose; Cronin,
   Meghan; Dombard, Andrew; Donohue, Kathleen; Flesch, Lucy; Giannini,
   Alessandra; Hayes, Gavin; Hogg, Andrew; Ilyina, Tatiana; Ivanov,
   Valeriy; Jacobsen, Steven; Korte, Monika; Lu, Gang; Morlighem, Mathieu;
   Magnusdottir, Gudrun; Newman, Andrew; Opher, Merav; Passalacqua,
   Paola; Patricola, Christina; Ritsema, Jeroen; Sprintall, Janet; Su,
   Hui; Thornton, Joel; Williams, Paul; Yau, Andrew
2019GeoRL..4612608R    Altcode:
  On behalf of the journal, AGU, and the scientific community, the
  Editors would like to sincerely thank those who reviewed manuscripts for
  Geophysical Research Letters in 2018. The hours reading and commenting
  on manuscripts not only improves the manuscripts but also increases
  the scientific rigor of future research in the field. We particularly
  appreciate the timely reviews, in light of the demands imposed by the
  rapid review process at Geophysical Research Letters. With the revival
  of the "major revisions" decisions, we appreciate the reviewers' efforts
  on multiple versions of some manuscripts. Many of those listed below
  went beyond and reviewed three or more manuscripts for our journal, and
  those are indicated in italics. In total, 4,484 referees contributed to
  7,557 individual reviews in journal. Thank you again. We look forward
  to the coming year of exciting advances in the field and communicating
  those advances to our community and to the broader public.

---------------------------------------------------------
Title: Principles Of Heliophysics: a textbook on the universal
    processes behind planetary habitability
Authors: Schrijver, Karel; Bagenal, Fran; Bastian, Tim; Beer,
   Juerg; Bisi, Mario; Bogdan, Tom; Bougher, Steve; Boteler, David;
   Brain, Dave; Brasseur, Guy; Brownlee, Don; Charbonneau, Paul; Cohen,
   Ofer; Christensen, Uli; Crowley, Tom; Fischer, Debrah; Forbes, Terry;
   Fuller-Rowell, Tim; Galand, Marina; Giacalone, Joe; Gloeckler, George;
   Gosling, Jack; Green, Janet; Guetersloh, Steve; Hansteen, Viggo;
   Hartmann, Lee; Horanyi, Mihaly; Hudson, Hugh; Jakowski, Norbert;
   Jokipii, Randy; Kivelson, Margaret; Krauss-Varban, Dietmar; Krupp,
   Norbert; Lean, Judith; Linsky, Jeff; Longcope, Dana; Marsh, Daniel;
   Miesch, Mark; Moldwin, Mark; Moore, Luke; Odenwald, Sten; Opher, Merav;
   Osten, Rachel; Rempel, Matthias; Schmidt, Hauke; Siscoe, George;
   Siskind, Dave; Smith, Chuck; Solomon, Stan; Stallard, Tom; Stanley,
   Sabine; Sojka, Jan; Tobiska, Kent; Toffoletto, Frank; Tribble, Alan;
   Vasyliunas, Vytenis; Walterscheid, Richard; Wang, Ji; Wood, Brian;
   Woods, Tom; Zapp, Neal
2019arXiv191014022S    Altcode:
  This textbook gives a perspective of heliophysics in a way that
  emphasizes universal processes from a perspective that draws attention
  to what provides Earth (and similar (exo-)planets) with a relatively
  stable setting in which life as we know it can thrive. The book is
  intended for students in physical sciences in later years of their
  university training and for beginning graduate students in fields of
  solar, stellar, (exo-)planetary, and planetary-system sciences.

---------------------------------------------------------
Title: Coronal disturbances and their effects on the dynamics of
    the heliosphere
Authors: Provornikova, Elena; Merkin, Vyacheslav; Opher, Merav;
   Richardson, John; Izmodenov, Vladislav; Brandt, Pontus; McNutt, Ralph
2019EPSC...13.1229P    Altcode:
  The Sun blows out the solar wind which propagates into the
  interplanetary medium and forms the heliosphere about 100 AU across. The
  solar activity causes various types of time-dependent phenomena in the
  solar wind from long-lived corotating interaction regions to shorter
  on duration but more extreme events like coronal mass ejections. As
  these structures propagate outward from the Sun, they evolve and
  interact with each other and the ambient solar wind. Voyager 1 and
  2 provided first unique in-situ measurements of these structures in
  the outer heliosphere. In particular, Voyager observations in the
  heliosheath, the outermost region of the heliosphere, showed highly
  variable plasma flows indicating effects of solar variations extending
  from the Sun to the heliosphere boundaries. Most surprisingly, Voyager
  1 data shows shocks and pressure waves beyond the heliosphere in the
  interstellar medium. Important questions for the future Interstellar
  Probe mission are (1) how do the heliosphere boundaries respond to solar
  variations? (2) how do disturbances evolve in the heliosheath? and (3)
  how far does the Sun influence extend into the interstellar medium? This
  talk will review observations and recent modeling efforts demonstrating
  highly variable and dynamic nature of the global heliosphere in response
  to disturbances originated in the Sun's atmosphere.

---------------------------------------------------------
Title: Corrugated Features in Coronal-mass-ejection-driven Shocks:
    A Discussion on the Predisposition to Particle Acceleration
Authors: Páez, A.; Jatenco-Pereira, V.; Falceta-Gonçalves, D.;
   Opher, M.
2019ApJ...879..122P    Altcode: 2019arXiv190707884P
  The study of the acceleration of particles is an essential element of
  research in heliospheric science. Here, we discuss the predisposition to
  the particle acceleration around shocks driven by coronal mass ejections
  (CMEs) with corrugated wave-like features. We adopt these attributes
  on shocks formed from disturbances due to the bimodal solar wind, CME
  deflection, irregular CME expansion, and the ubiquitous fluctuations
  in the solar corona. In order to understand the role of a wavy shock in
  particle acceleration, we define three initial smooth shock morphologies
  each associated with a fast CME. Using polar Gaussian profiles we
  model these shocks in the low corona. We establish the corrugated
  appearance on smooth shock by using combinations of wave-like functions
  that represent the disturbances from the medium and CME piston. For
  both shock types, smooth and corrugated, we calculate the shock normal
  angles between the shock normal and the radial upstream coronal magnetic
  field in order to classify the quasi-parallel and quasi-perpendicular
  regions. We consider that corrugated shocks are predisposed to different
  processes of particle acceleration due to irregular distributions of
  shock normal angles around the shock. We suggest that disturbances
  due to CME irregular expansion may be a decisive factor in origin of
  particle acceleration. Finally, we regard that accepting these features
  on shocks may be the starting point for investigating some questions
  regarding the sheath and shock, like downstream jets, instabilities,
  shock thermalization, shock stability, and injection particle processes.

---------------------------------------------------------
Title: Community Input Solicited for Heliophysics Decadal Survey
    Midterm Assessment Committee
Authors: Woods, Thomas; Millan, Robyn; Charo, Art; Bastian, Tim;
   Bobra, Monica; Coster, Anthea; DeLuca, Ed; England, Scott; Fuselier,
   Stephen; Lopez, Ramon; Luhmann, Janet; Nykyri, Katariina; Oberheide,
   Jens; Opher, Merav; Schrijver, Karel; Semeter, Josh; Thayer, Jeff;
   Title, Alan
2019shin.confE...6W    Altcode:
  The National Academies of Sciences, Engineering, and Medicine has
  convened a committee to review the progress towards implementing the
  2013 Heliophysics Decadal Survey, titled Solar and Space Physics: a
  Science for a Technological Society. This review serves as a midterm
  assessment before the next Heliophysics Decadal Survey committee would
  begin its formulation. This committee is interested to receive input
  from the heliophysics and space weather communities about the 2013-2018
  progress realizing the 15 recommendations and applications specified in
  the 2013 Heliophysics Decadal Survey, about any suggested actions to
  optimize the science value during 2019-2023, about any suggestions to
  improve the process for the next Heliophysics Decadal Survey, and about
  any suggested actions to enhance all stages of careers for scientists
  and engineers in the solar and space physics community. This poster
  outlines the Heliophysics Decadal Survey recommendations and recent
  progress, and it also summarizes the tasks for this midterm assessment
  committee. There will be an opportunity to discuss your inputs with
  a couple of the Committee members during the SHINE meeting.

---------------------------------------------------------
Title: Major Scientific Challenges and Opportunities in Understanding
    Magnetic Reconnection and Related Explosive Phenomena throughout
    the Universe
Authors: Ji, Hantao; Alt, A.; Antiochos, S.; Baalrud, S.; Bale, S.;
   Bellan, P. M.; Begelman, M.; Beresnyak, A.; Blackman, E. G.; Brennan,
   D.; Brown, M.; Buechner, J.; Burch, J.; Cassak, P.; Chen, L. -J.;
   Chen, Y.; Chien, A.; Craig, D.; Dahlin, J.; Daughton, W.; DeLuca, E.;
   Dong, C. F.; Dorfman, S.; Drake, J.; Ebrahimi, F.; Egedal, J.; Ergun,
   R.; Eyink, G.; Fan, Y.; Fiksel, G.; Forest, C.; Fox, W.; Froula, D.;
   Fujimoto, K.; Gao, L.; Genestreti, K.; Gibson, S.; Goldstein, M.;
   Guo, F.; Hesse, M.; Hoshino, M.; Hu, Q.; Huang, Y. -M.; Jara-Almonte,
   J.; Karimabadi, H.; Klimchuk, J.; Kunz, M.; Kusano, K.; Lazarian,
   A.; Le, A.; Li, H.; Li, X.; Lin, Y.; Linton, M.; Liu, Y. -H.; Liu,
   W.; Longcope, D.; Louriero, N.; Lu, Q. -M.; Ma, Z. -W.; Matthaeus,
   W. H.; Meyerhofer, D.; Mozer, F.; Munsat, T.; Murphy, N. A.; Nilson,
   P.; Ono, Y.; Opher, M.; Park, H.; Parker, S.; Petropoulou, M.; Phan,
   T.; Prager, S.; Rempel, M.; Ren, C.; Ren, Y.; Rosner, R.; Roytershteyn,
   V.; Sarff, J.; Savcheva, A.; Schaffner, D.; Schoeffier, K.; Scime, E.;
   Shay, M.; Sitnov, M.; Stanier, A.; TenBarge, J.; Tharp, T.; Uzdensky,
   D.; Vaivads, A.; Velli, M.; Vishniac, E.; Wang, H.; Werner, G.; Xiao,
   C.; Yamada, M.; Yokoyama, T.; Yoo, J.; Zenitani, S.; Zweibel, E.
2019BAAS...51c...5J    Altcode: 2019astro2020T...5J
  This is a group white paper of 100 authors (each with explicit
  permission via email) from 51 institutions on the topic of magnetic
  reconnection which is relevant to 6 thematic areas. Grand challenges
  and research opportunities are described in observations, numerical
  modeling and laboratory experiments in the upcoming decade.

---------------------------------------------------------
Title: A Predicted Small and Round Heliosphere
Authors: Opher, Merav; Loeb, Abraham; Drake, James; Toth, Gabor
2019EGUGA..2111837O    Altcode:
  The shape of the solar wind bubble within the interstellar medium, the
  so-called heliosphere, has been explored over six decades (Davis 55;
  Parker '61; Axford '72; Baranov &amp; Malama '93). As the Sun moves
  through the surrounding partially-ionized medium, neutral hydrogen
  atoms penetrate the heliosphere, and through charge-exchange with
  the supersonic solar wind, create a population of hot pick-up ions
  (PUIs). The Voyager 2 (V2) data demonstrated that the heliosheath
  pressure is dominated by PUIs. Here we use a novel magnetohydrodynamic
  model that treats the PUIs as a separate fluid from the thermal
  component of the solar wind. Unlike previous models, the new model
  reproduces the properties of the PUIs and solar wind ions based on
  the New Horizon (McComas et al. 2017) and V2 (Richardson et al. 2008)
  spacecraft observations. The model significantly changes the energy
  flow in the outer heliosphere, leading to a smaller and rounder shape
  than previously predicted, in agreement with energetic neutral atom
  observations by the Cassini spacecraft (Dialynas et al. 2017). We
  will discuss the consequences of this new shape for draping of the
  interstellar magnetic field and conditions at Voyager 1 and 2 in the
  local interstellar medium.

---------------------------------------------------------
Title: Globally Distributed Energetic Neutral Atom Maps for the
    “Croissant” Heliosphere
Authors: Kornbleuth, M.; Opher, M.; Michael, A. T.; Drake, J. F.
2018ApJ...865...84K    Altcode: 2018arXiv180805997K
  A recent study by Opher et al. suggested the heliosphere has a
  “croissant” shape, where the heliosheath plasma is confined by the
  toroidal solar magnetic field. The “croissant” heliosphere is in
  contrast to the classically accepted view of a comet-like tail. We
  investigate the effect of the “croissant” heliosphere model on
  energetic neutral atom (ENA) maps. Regardless of the existence of a
  split tail, the confinement of the heliosheath plasma should appear in
  ENA maps. ENA maps from the Interstellar Boundary Explorer (IBEX) have
  shown two high latitude lobes with excess ENA flux at higher energies
  in the tail of the heliosphere. These lobes could be a signature of
  the confinement of the heliosheath plasma, while some have argued
  they are caused by the fast/slow solar wind profile. Here we present
  ENA maps of the “croissant” heliosphere, focusing on understanding
  the effect of the heliosheath plasma collimation by the solar magnetic
  field while using a uniform solar wind. We incorporate pick-up ions
  (PUIs) into our model based on Malama et al. and Zank et al. We use the
  neutral solution from our MHD model to determine the angular variation
  of the PUIs, and include the extinction of PUIs in the heliosheath. In
  the presence of a uniform solar wind, we find that the collimation
  in the “croissant” heliosphere does manifest itself into two high
  latitude lobes of increased ENA flux in the downwind direction.

---------------------------------------------------------
Title: A Predicted Small and Round Heliosphere
Authors: Opher, Merav; Loeb, Abraham; Drake, James; Toth, Gabor
2018arXiv180806611O    Altcode:
  The shape of the solar wind bubble within the interstellar medium,
  the so-called heliosphere, has been explored over six decades. As the
  Sun moves through the surrounding partially-ionized medium, neutral
  hydrogen atoms penetrate the heliosphere, and through charge-exchange
  with the supersonic solar wind, create a population of hot pick-up
  ions (PUIs). The Termination Shock (TS) crossing by Voyager 2 (V2)
  data demonstrated that the heliosheath (HS) (the region of shocked
  solar wind) pressure is dominated by suprathermal particles. Here we
  use a novel magnetohydrodynamic model that treats the freshly ionized
  PUIs as a separate fluid from the thermal component of the solar
  wind. Unlike previous models, the new model reproduces the properties of
  the PUIs and solar wind ions based on the New Horizon and V2 spacecraft
  observations. The PUIs charge exchange with the cold neutral H atoms of
  the ISM in the HS and are quickly depleted. The depletion of PUIs cools
  the heliosphere downstream of the TS, "deflating" it and leading to a
  narrower HS and a smaller and rounder shape, in agreement with energetic
  neutral atom observations by the Cassini spacecraft. The new model, with
  interstellar magnetic field orientation constrained by the IBEX ribbon,
  reproduces the magnetic field data outside the HP at Voyager 1(V1). We
  present the predictions for the magnetic field outside the HP at V2.

---------------------------------------------------------
Title: The Astrosphere and Mass-Loss Ratio of Proxima Centauri
Authors: Opher, Merav; Toth, Gabor; Loeb, Abraham
2018cosp...42E2514O    Altcode:
  Our understanding about the heliosphere dramatically evolved from
  the results from Voyager, Cassini and Interstellar Boundary Explorer
  (IBEX). With the rapid discovery of exoplanets in other stellar systems
  it is important to understand how this new acquired knowledge affects
  the astrospheres around other stars. In particular, recently the shape
  of the Heliosphere is being challenged by theoretical and observation
  work (Opher et al. 2015; Diyalinas et al. 2017). The nearest star to the
  Sun, Proxima Centauri, is particularly interesting as it was recently
  discovered to host an Earth-size planet in its "habitable zone", Proxima
  b. Here we investigate the astrosphere around Proxima Centauri. As the
  star moves through the surrounding partially-ionized medium, neutral
  hydrogen atoms penetrate the astrospheres and through charge-exchange
  with the supersonic stellar wind creating a population of hot pick-up
  ions (PUIs). We present global magnetohydrodynamic simulations that
  treats the PUIs as a separate fluid. Most global models treat the PUI
  and thermal component as a single fluid. Planetary atmospheres are
  affected by particle fluxes from their host stars. The only means
  by which coronal winds of Sun-like stars have ever been probed is
  by the circumstellar H Lyman-alpha absorption fin the interaction
  region between the wind and the interstellar medium, namely the
  "astrospheres". The Lyman-alpha constrains on the stellar wind based
  on Hubble Space Telescope measurements rely on prior hydrodynamical
  models. Here we revisit the constraints on the mass-loss of Proxima
  Centauri (Wood et al. 2011) with improved theoretical predictions and
  discuss the implications for Space Weather effects on Proxima b.

---------------------------------------------------------
Title: The effects of Pick-up Ions on the Shape of The Heliosphere
Authors: Opher, Merav; Toth, Gabor; Loeb, Abraham
2018cosp...42E2513O    Altcode:
  As the Sun moves through the surrounding partially-ionized medium,
  neutrals hydrogen atom penetrate the heliosphere and through
  charge-exchange with the supersonic solar wind create a population of
  hot pick-up ions (PUIs). With the crossing of the termination shock by
  Voyager 2 it became clear that the heliosheath pressure is dominated
  by the PUIs while the bulk thermal solar wind is much colder. Recently
  the shape of the Heliosphere is being challenged by theoretical and
  observation work (Opher et al. 2015; Diyalinas et al. 2017). Previously
  we had explored the effects of PUIs in the termination shock crossing
  (Zieger et al. 2015). In this work, we explore the effects of PUIs on
  the shape of the heliosphere. We present global magnetohydrodynamic
  simulations that treats the PUIs a separate fluid. Most global models
  treat the PUI and thermal component as a single fluid. We comment
  on the effect of the global structure as well as the properties of
  the heliosheath.

---------------------------------------------------------
Title: Consequences of Treating the Solar Magnetic Field as a Dipole
    on the Global Structure of the Heliosphere and Heliosheath
Authors: Michael, A. T.; Opher, M.; Tóth, G.
2018ApJ...860..171M    Altcode:
  We investigate the effect of including the heliospheric current sheet
  on global modeling of the heliosphere. Due to inherent numerical
  dissipation in the current handling of the heliospheric current sheet,
  models have chosen to remove it to avoid numerical problems. We compare
  a model where the polarity of the Parker spiral is the same in both
  hemispheres (unipolar) to a dipole description of the solar magnetic
  field, with the magnetic and rotational axes aligned forming a flat
  heliospheric current sheet. The flat current sheet is pulled into the
  northern hemisphere, which reduces the magnetic field strength at the
  Voyager 1 trajectory over the last 22% of the heliosheath. The decrease
  in magnetic field intensity is transferred into the thermal energy of
  the plasma causing the dipole model to predict an entirely thermally
  dominated heliosheath; this is a stark contrast to the magnetically
  dominated region ahead of the heliopause in the unipole model. We
  find that the two-lobe structure of the solar wind magnetic field
  persists within the dipole model, with the flat current sheet not
  able to fully erode the magnetic tension force. However, there is a
  large amount of magnetic dissipation in the tail between the lobes,
  which affects the structure of the plasma in the region. Furthermore,
  the draped interstellar magnetic field in the dipole model is strongly
  affected by reconnection at the nose of the heliosphere, yielding a
  distinctly different draping pattern than that observed at Voyager 1.

---------------------------------------------------------
Title: Effects of Neutrals in the Outer Heliosphere- lessons learned
    from Voyager, Cassini, IBEX, about our home in the galaxy
Authors: Opher, Merav
2018tess.conf40003O    Altcode:
  In this talk, I will discuss what we recently learned from
  the in-situ measurements from Voyager spacecraft as well as the
  remote sensing of energetic neutral atoms from CASSINI, IBEX about
  the heliosphere. Interstellar Boundary Explorer (IBEX) is being
  observing the heliosphere with maps of energetic neutral atoms (ENAs)
  from 1-6keV. INCA on board of CASSINI is taking ENA images of the
  heliosphere in energies 5-55keV. Voyager 2 is still exploring the
  heliosheath while of Voyager 1 spacecraft is measuring the local
  interstellar medium since 2012. In particular I will review the
  effects of neutral H atoms streaming from the Interstellar Medium
  have on the heliosphere. The heliosphere is the only local example
  of astrosphere that can be probed in such details. As the Sun moves
  through the surrounding partially-ionized medium, neutrals hydrogen
  atom penetrate the heliosphere and through charge-exchange with
  the supersonic solar wind create a population of hot pick-up ions
  (PUIs). With the crossing of the termination shock by Voyager 2 it
  became clear that the heliosheath pressure is dominated by the PUIs
  while the bulk thermal solar wind is much colder. From the Energetic
  Neutral Atoms images of IBEX and CASSINI our knowledge was transformed
  about the shape of the heliosphere, as well as processes occurring in
  the very local interstellar medium ahead of the heliosphere. I will
  review these different different measurements and comment in particular
  about the recent debate where the shape of the Heliosphere is being
  challenged by theoretical and observation work (Opher et al. 2015;
  Diyalinas et al. 2017) and what we can learn from future missions such
  as IMAP.

---------------------------------------------------------
Title: Appreciation of 2017 GRL Peer Reviewers
Authors: Diffenbaugh, Noah; Beal, Lisa; Bayani Cardenas, M.; Cobb,
   Kim; Cory, Rose; Cronin, Meghan; Dombard, Andrew J.; Hogg, Andrew;
   Ilyina, Tatiana; Korte, Monika; Lu, Gang; Magnusdottir, Gudrun; Newman,
   Andrew V.; Opher, Merav; Ritsema, Jeroen; Sprintall, Janet; Stroeve,
   Julienne; Thornton, Joel A.; Williams, Paul D.; Yau, Andrew
2018GeoRL..45.4494D    Altcode:
  Thank you to those who reviewed in 2017 for Geophysical Research
  Letters.

---------------------------------------------------------
Title: A Science-Driven Mission to an Exoplanet
Authors: Weinstein-Weiss, S.; Rayman, Marc; Turyshev, Slava; Biswass,
   Abhijit; Jun, Insoo; Price, Hoppy; Mamajek, Eric; Callas, John;
   McElrath, Tim; Woerner, Dave; Brophy, John; Shao, Mike; Alkalai, Leon;
   Arora, Nitin; Johnson, Les; Opher, Merav; Redfield, Seth; McNutt,
   Ralph; Sotker, Carol; Blank, Jennifer; Caldwell, Douglas; Friedman,
   Louis; Frisbee, Robert; Bennett, Gary
2018JBIS...71..140W    Altcode:
  A concept for a science-driven robotic mission to an exoplanet was
  developed based on key mission and science requirements designed to
  address the question: "What makes a flight mission to an exoplanet
  compelling, in terms of science return, compared to what will be
  learned in the next few decades with large near-Earth telescopes
  or other remote sensing techniques such as a telescope at the Solar
  Gravity Lens Focus?" By thinking systematically through mission and
  science goals as well as objectives, key requirements were developed
  that would drive technology developments in all necessary aspects,
  not just on propulsion. One of the key mission science objectives
  was to confirm and characterize life. The team concluded that a direct
  confirmation of life would require in situ observations and measurements
  that cannot be performed on a fast (0.1c) flyby; thus, the mission would
  require a method to slow down, orbit or send a probe to the exoplanet's
  surface. This capability drives a trade between interstellar travel
  velocity, trip duration and propulsion architecture as well as a high
  level of onboard autonomy, including adaptive science data collection,
  on-board data processing and analysis. This paper describes the mission
  concept, the key requirements and open trades.

---------------------------------------------------------
Title: The Structure of the Heliosphere with Solar Cycle and Its
    Effect on the Conditions in the Local ISM
Authors: Opher, M.; Drake, J. F.; Toth, G.; Swisdak, M.; Michael,
   A.; Kornbleuth, M. Z.; Zieger, B.
2017AGUFMSH54B..04O    Altcode:
  We argued (Opher et al. 2015, Drake et al. 2015) that the magnetic
  tension of the solar magnetic field plays a crucial role in
  organizing the solar wind in the heliosheath into two jet-like
  structures. The heliosphere then has a "croissant"-like shape where
  the distance to the heliopause downtail is almost the same as towards
  the nose. Regardless of whether the heliospheric tail is split in two
  or has a long comet shape there is consensus that the magnetic field
  in the heliosheath behaves differently than previously expected -
  it has a "slinky" structure and is turbulent. In this presentation,
  we will discuss several aspects related with this new model. We will
  show that this structure persists when the solar magnetic field is
  treated as a dipole. We show how the heliosphere, with its "Croissant"
  shape, evolves when the solar wind with solar cycle conditions are
  included and when the neutrals are treated kinetically (with our new
  MHD-Kinetic code). Due to reconnection (and turbulence of the jets)
  there is a substantial amount of heliosheath material sitting on open
  field lines. We will discuss the impact of artificial dissipation
  of the magnetic field in driving mixing and how it evolves with the
  solar cycle. We will discuss as well the development of turbulence
  in the jets and its role in mixing the plasma in the heliosheath and
  LISM and controlling the global structure of the heliosphere. We will
  discuss how the conditions upstream of the heliosphere, in the local
  interstellar medium are affected by reconnection in the tail and how it
  evolves with solar cycle. Recently we established (Opher et al. 2017)
  that reconnection in the eastern flank of the heliosphere is responsible
  for the twist of the interstellar magnetic field (BISM) acquiring a
  strong east-west component as it approaches the Heliopause. Reconnection
  drives a rotational discontinuity (RD) that twists the BISM into the
  -T direction and propagates upstream in the interstellar medium toward
  the nose. The consequence is that the N component of BISM is reduced in
  a band upstream of the HP. We show how the location of the RD upstream
  of the heliopause is affected by the solar cycle.

---------------------------------------------------------
Title: The Energetic Neutral Atoms of the "Croissant" Heliosphere
    with Jets
Authors: Kornbleuth, M. Z.; Opher, M.; Michael, A.
2017AGUFMSH51D2535K    Altcode:
  Opher et al. (2015) suggests the heliosphere may have two jets in the
  tail-ward direction driven to the north and south. This new model, the
  "Croissant Heliosphere", is in contrast to the classically accepted
  view of a comet-like tail. We investigate the effect of the heliosphere
  with jets model on energetic neutral atom (ENA) maps. Regardless of
  the existence of a split tail, other models show heliosheath plasma
  confined by the toroidal magnetic field in a "slinky" structure, similar
  to astrophysical jets bent by the interstellar medium. Therefore,
  the confinement of the plasma should appear in the ENA maps. ENA maps
  from the Interstellar Boundary Explorer (IBEX) have recently shown
  two high latitude lobes with excess ENA flux at higher energies in
  the tail of the heliosphere. These lobes could be a signature of the
  two jet structure of the heliosphere, while some have argued they are
  cause by the fast/slow solar wind profile. Here we present the ENA
  maps of the "Croissant Heliosphere" using initially a uniform solar
  wind. We incorporate pick-up ions (PUIs) into our model based on the
  kinetic modeling of Malama et al. (2006). We include the extinction of
  PUIs in the heliosheath and describe a locally created PUI population
  resulting from this extinction process. Additionally, we include the
  angular dependence of the PUIs based on the work of Vasyliunas &amp;
  Siscoe (1976). With our model, we find that, in the presence of a
  uniform solar wind, the "heliosphere with jets" model is able to
  qualitatively reproduce the lobe structure of the tail seen in IBEX
  measurements. Turbulence also manifests itself within the lobes of the
  simulated ENA maps on the order of years. Finally we will present ENA
  maps using a time-dependent model of the heliosphere with the inclusion
  of solar cycle.

---------------------------------------------------------
Title: From the Outside Looking In - Looking Back at Our Heliosphere
    in Energetic Neutral Atoms
Authors: Demajistre, R.; Brandt, P. C.; Gruntman, M.; McNutt, R. L.,
   Jr.; Opher, M.; Roelof, E. C.; Wood, B. E.
2017AGUFMSH23B2655D    Altcode:
  Energetic Neutral Atoms (ENAs) have been used over the past two
  decades to image space plasmas in planetary magnetospheres as well
  as the structure of the heliosheath. Any energetic plasma containing
  singly charged ions embedded in a cold neutral gas will 'glow' in ENAs,
  and this glow can be analyzed to infer the properties of the source
  plasma, giving us insight into processes that are difficult to study
  with the more traditional sensors that use photons/electromagnetic
  waves as an information carrier. ENA measurements of the heliosphere
  have (obviously) all been taken from vantage points in the inner
  heliosphere. ENAs created in the inner heliosphere from the solar wind
  and Pick Up Ions (PUIs) generally have large outward velocity, and
  thus do not reach sensors closer to the sun. Thus, the plasma is only
  'visible' in ENAs to an inner heliosphere observer after it reaches
  the termination shock, where its outward motion is slowed and it is
  heated. This perspective from the inside looking out is convenient to
  study the outer boundary of the heliophere, but contains no direct
  information about the plasma and processes occurring in the inner
  heliosphere. ENA sensors placed outside the heliosphere, conversely
  would allow us to remotely sense both the inner and outer heliosphere,
  allowing us full access to the evolution of the solar wind and PUIs as
  they travel from the sun outward. Further, such a perspective would
  allow us to more directly measure the boundaries of the heliosphere
  with the LISM without the obscuration of the inner heliosheath. In this
  paper, we present modeled views of ENA images from the outside looking
  in at energies between 0.5 and 100 keV. It is important to note that
  while measurements of the outer heliosphere have been made by IBEX,
  Cassini/INCA, SoHO/HSTOF and the Voyagers, there are still important
  outstanding questions about the global structure and plasma flow
  patterns in the heliosphere. We will show here how new observations
  from the outside looking in can be used to address these questions.

---------------------------------------------------------
Title: Kelvin-Helmholtz Instability at the CME-Sheath and
    Sheath-Solar-wind Interfaces
Authors: Páez, A.; Jatenco-Pereira, V.; Falceta-Gonçalves, D.;
   Opher, M.
2017ApJ...851..112P    Altcode:
  Wave-like features recently observed in some coronal mass ejections
  (CMEs) have been associated with the presence of Kelvin-Helmholtz
  instability (KHI) in the low corona. Previous works found observational
  evidence of KHI in a CME; this was followed by numerical simulations
  in order to determine the magnetic field strength allowing for its
  existence. Here, we present the first discussion of KHI formation in
  the outer corona at heliocentric distances from 4 {R}<SUB>⊙ </SUB>
  to 30 {R}<SUB>⊙ </SUB>. We study separately the CME-sheath and
  sheath-solar-wind (Sh-SW) interfaces of two CMEs that propagated in
  the slow and fast SWs. Mapping the velocities, densities, and magnetic
  field strengths of the CMEs, sheaths, and SWs in the CME’s flanks,
  we solve the Chandrasekhar condition for KHI formation. Calculations
  show that KHI formation is more likely in a CME propagating in a slow
  SW (CME 1) than that propagating in a fast SW due to the large shear
  flow between the CME and the slow SW. Comparing the interfaces for
  both CME cases, we note that the Sh-SW interface of CME 1 is more
  conducive to the instability because of the similar strengths of the
  magnetic field necessary for KHI formation and of the SW magnetic field.

---------------------------------------------------------
Title: Results from the OH-PT model: a Kinetic-MHD Model of the
    Outer Heliosphere within SWMF
Authors: Michael, A.; Opher, M.; Tenishev, V.; Borovikov, D.; Toth, G.
2017AGUFMSH23C2676M    Altcode:
  We present an update of the OH-PT model, a kinetic-MHD model of the
  outer heliosphere. The OH-PT model couples the Outer Heliosphere (OH)
  and Particle Tracker (PT) components within the Space Weather Modeling
  Framework (SWMF). The OH component utilizes the Block-Adaptive Tree
  Solarwind Roe-type Upwind Scheme (BATS-R-US) MHD code, a highly
  parallel, 3D, and block-adaptive solver. As a stand-alone model,
  the OH component solves the ideal MHD equations for the plasma and
  a separate set of Euler's equations for the different populations of
  neutral atoms. The neutrals and plasma in the outer heliosphere are
  coupled through charge-exchange. While this provides an accurate
  solution for the plasma, it is an inaccurate description of the
  neutrals. The charge-exchange mean free path is on the order of the
  size of the heliosphere; therefore the neutrals cannot be described
  as a fluid. The PT component is based on the Adaptive Mesh Particle
  Simulator (AMPS) model, a 3D, direct simulation Monte Carlo model
  that solves the Boltzmann equation for the motion and interaction of
  multi-species plasma and is used to model the neutral distribution
  functions throughout the domain. The charge-exchange process occurs
  within AMPS, which handles each event on a particle-by-particle basis
  and calculates the resulting source terms to the MHD equations. The
  OH-PT model combines the MHD solution for the plasma with the kinetic
  solution for the neutrals to form a self-consistent model of the
  heliosphere. In this work, we present verification and validation of
  the model as well as demonstrate the codes capabilities. Furthermore we
  provide a comparison of the OH-PT model to our multi-fluid approximation
  and detail the differences between the models in both the plasma
  solution and neutral distribution functions.

---------------------------------------------------------
Title: Understanding the Heliosphere with Jets Using Energetic
    Neutral Atoms
Authors: Kornbleuth, Marc Zachary; Opher, Merav; Michael, Adam
2017shin.confE.167K    Altcode:
  The Interstellar Boundary Explorer (IBEX) has been probing the
  global structure of the heliosphere using energetic neutral atoms
  (ENAs). McComas et al. (2013) showed the presence of two high latitude
  lobes of increased ENA flux at higher energies in IBEX measurements. It
  was suggested that these measurements could be the result of slow/fast
  wind in the heliosphere affecting the measured ENA flux. Recently, Opher
  et al. (2015) proposed the heliosphere might have two turbulent jets
  in the tail region, as opposed to the classically view of a quiescent,
  comet-like structure in the tail. If confirmed, this heliosphere with
  jets model would significantly change our understanding of how the
  interstellar medium interacts with the solar wind. We use the Opher et
  al. (2015) model to create simulated ENA maps of the heliosphere. Our
  ENA code is based on a previously created code from Prested et
  al. (2008) and Opher et al. (2013). We incorporate multiple pick-up ion
  populations, extinction along streamlines, and a pick-up ion profile
  based on Vasyliunas &amp; Siscoe (1976) that depends on the latitude
  and longitude with respect to the neutral streaking direction. Using
  our MHD model with a uniform solar wind, we find two high latitude
  lobes present in our simulated maps which are consistent with IBEX
  measurements. We also find small-scale changes in the lobes resulting
  from turbulence in the jets, which should be observable by IBEX or IMAP.

---------------------------------------------------------
Title: Consequences of treating the solar magnetic field as a dipole
    on the global structure of the heliosphere and an update on the
    OH-PT model
Authors: Michael, Adam Thomas; Opher, Merav; Toth, Gabor; Tenishev,
   Valeriy; Borovikov, Dmitry
2017shin.confE.168M    Altcode:
  Through the use of numerical models, we have begun to realize the
  importance the solar magnetic field has on the heliosphere. The aim
  of all outer heliosphere simulations is to accurately model the solar
  magnetic field, including a self-consistent approach to the heliospheric
  current sheet. We investigate the effect that including the heliospheric
  current sheet has on our global 3D MHD model of the heliosphere. We
  compare the unipolar model, where the polarity of the Parker spiral
  is the same in both hemispheres, to the dipole description of the
  solar magnetic field with the magnetic and rotational axes aligned
  forming a flat heliospheric current sheet, defined as a discontinuity
  between polarities. The flat current sheet is pulled into the northern
  hemisphere, avoiding the stagnation region, and reduces the magnetic
  field strength at the Voyager 1 trajectory over the last 22.5% of the
  heliosheath. The decrease in magnetic field intensity is transferred
  into the thermal energy of the plasma causing the dipole model to
  predict an entirely thermally dominated heliosheath, a stark contrast
  to the magnetically dominated region ahead of the heliopause in the
  unipole model. The jet that forms within the current sheet increases
  the radial velocity and ram pressure just downstream of the heliopause
  causing the heliopause to be asymmetric and located further in the
  northern hemisphere. We find that the two-lobe structure of the solar
  wind magnetic field persists within the dipole model with the flat
  current sheet not able to fully erode the magnetic tension force. We
  also present an update of the OH-PT model within SWMF. The OH-PT model
  is a kinetic-MHD model that couples the BATS-R-US MHD solver to AMPS,
  a DSMC code used to solve the Boltzmann equation for the distribution
  function of the neutrals and energetic neutral atoms streaming through
  the heliosphere.

---------------------------------------------------------
Title: Variability of Jupiter's IR H<SUB>3</SUB><SUP>+</SUP> aurorae
    during Juno approach
Authors: Moore, L.; O'Donoghue, J.; Melin, H.; Stallard, T.; Tao,
   C.; Zieger, B.; Clarke, J.; Vogt, M. F.; Bhakyapaibul, T.; Opher,
   M.; Tóth, G.; Connerney, J. E. P.; Levin, S.; Bolton, S.
2017GeoRL..44.4513M    Altcode:
  We present ground-based observations of Jupiter's
  H<SUB>3</SUB><SUP>+</SUP> aurorae over four nights in April 2016
  while the Juno spacecraft was monitoring the upstream interplanetary
  magnetic field. High-precision maps of auroral H<SUB>3</SUB><SUP>+</SUP>
  densities, temperatures, and radiances reveal significant variabilities
  in those parameters, with regions of enhanced density and emission
  accompanied by reduced temperature. Juno magnetometer data,
  combined with solar wind propagation models, suggest that a shock
  may have impacted Jupiter in the days preceding the observation
  interval but that the solar wind was quiescent thereafter. Auroral
  H<SUB>3</SUB><SUP>+</SUP> temperatures reveal a downward temporal trend,
  consistent with a slowly cooling upper atmosphere, such as might follow
  a period of shock recovery. The brightest H<SUB>3</SUB><SUP>+</SUP>
  emissions are from the end of the period, 23 April. A lack of
  definitive signatures in the upstream interplanetary magnetic field
  lends supporting evidence to the possibility that this brightening
  event may have been driven by internal magnetospheric processes.

---------------------------------------------------------
Title: The Twist of the Draped Interstellar Magnetic Field Ahead
of the Heliopause: A Magnetic Reconnection Driven Rotational
    Discontinuity
Authors: Opher, M.; Drake, J. F.; Swisdak, M.; Zieger, B.; Toth, G.
2017ApJ...839L..12O    Altcode: 2017arXiv170206178O
  Based on the difference between the orientation of the interstellar B
  <SUB>ISM</SUB> and the solar magnetic fields, there was an expectation
  that the magnetic field direction would rotate dramatically across
  the heliopause (HP). However, the Voyager 1 spacecraft measured
  very little rotation across the HP. Previously, we showed that the B
  <SUB>ISM</SUB> twists as it approaches the HP and acquires a strong
  T component (east-west). Here, we establish that reconnection in the
  eastern flank of the heliosphere is responsible for the twist. On the
  eastern flank the solar magnetic field has twisted into the positive N
  direction and reconnects with the southward pointing component of the
  B <SUB>ISM</SUB>. Reconnection drives a rotational discontinuity (RD)
  that twists the B <SUB>ISM</SUB> into the -T direction and propagates
  upstream in the interstellar medium toward the nose. The consequence is
  that the N component of B <SUB>ISM</SUB> is reduced in a finite width
  band upstream of the HP. Voyager 1 currently measures angles (δ ={\sin
  }<SUP>-1</SUP>({B}<SUB>N</SUB>/B)) close to solar values. We present MHD
  simulations to support this scenario, suppressing reconnection in the
  nose region while allowing it in the flanks, consistent with recent
  ideas about reconnection suppression from diamagnetic drifts. The
  jump in plasma β (the plasma to magnetic pressure) across the nose
  of HP is much greater than in the flanks because the heliosheath β is
  greater there than in the flanks. Large-scale reconnection is therefore
  suppressed in the nose but not at the flanks. Simulation data suggest
  that B <SUB>ISM</SUB> will return to its pristine value 10-15 au past
  the HP.

---------------------------------------------------------
Title: The Deflection of the Cartwheel CME: ForeCAT Results
Authors: Capannolo, Luisa; Opher, Merav; Kay, Christina; Landi, Enrico
2017ApJ...839...37C    Altcode:
  We analyze the Cartwheel coronal mass ejection's (CME; 2008 April 9)
  trajectory in the low corona with the ForeCAT model. This complex event
  presented a significant rotation in the low corona and a reversal
  in its original latitude direction. We successfully reproduce the
  observed CME’s trajectory (latitude and longitude deflection) and
  speed. Through a {χ }<SUP>2</SUP> test, we are able to constrain the
  CME’s mass to (2.3-3.0) × 10<SUP>14</SUP> g and the CME’s initial
  shape. We are able to constrain the expansion of the CME as well: the
  angular width linearly increases until 2.1 {R}<SUB>⊙ </SUB>, and is
  constant afterward. In order to match the observed latitude, we include
  a non-radial initial speed of -42 km s<SUP>-1</SUP>. Despite allowing
  the CME to rotate in the model, the magnetic forces of the solar
  background are not able to reproduce the observed rotation. We suggest
  that the complex reversal in latitude and the significant rotation of
  the Cartwheel CME can be justified with an asymmetrical reconnection
  event that ejected the CME non-radially and also initiated its rotation.

---------------------------------------------------------
Title: The Formation of Magnetic Depletions and Flux Annihilation
    Due to Reconnection in the Heliosheath
Authors: Drake, J. F.; Swisdak, M.; Opher, M.; Richardson, J. D.
2017ApJ...837..159D    Altcode: 2017arXiv170201697D
  The misalignment of the solar rotation axis and the magnetic axis of
  the Sun produces a periodic reversal of the Parker spiral magnetic
  field and the sectored solar wind. The compression of the sectors is
  expected to lead to reconnection in the heliosheath (HS). We present
  particle-in-cell simulations of the sectored HS that reflect the plasma
  environment along the Voyager 1 and 2 trajectories, specifically
  including unequal positive and negative azimuthal magnetic flux as
  seen in the Voyager data. Reconnection proceeds on individual current
  sheets until islands on adjacent current layers merge. At late time,
  bands of the dominant flux survive, separated by bands of deep magnetic
  field depletion. The ambient plasma pressure supports the strong
  magnetic pressure variation so that pressure is anticorrelated with
  magnetic field strength. There is little variation in the magnetic
  field direction across the boundaries of the magnetic depressions. At
  irregular intervals within the magnetic depressions are long-lived pairs
  of magnetic islands where the magnetic field direction reverses so that
  spacecraft data would reveal sharp magnetic field depressions with only
  occasional crossings with jumps in magnetic field direction. This is
  typical of the magnetic field data from the Voyager spacecraft. Voyager
  2 data reveal that fluctuations in the density and magnetic field
  strength are anticorrelated in the sector zone, as expected from
  reconnection, but not in unipolar regions. The consequence of the
  annihilation of subdominant flux is a sharp reduction in the number
  of sectors and a loss in magnetic flux, as documented from the Voyager
  1 magnetic field and flow data.

---------------------------------------------------------
Title: The Interstellar Probe Mission: Humanity's First Explicit
    Step in Reaching Another Star
Authors: Brandt, P. C.; McNutt, R.; Hallinan, G.; Shao, M.; Mewaldt,
   R.; Brown, M.; Alkalai, L.; Arora, N.; McGuire, J.; Turyshev, S.;
   Biswas, A.; Liewer, P.; Murphy, N.; Desai, M.; McComas, D.; Opher,
   M.; Stone, E.; Zank, G.; Friedman, L.
2017LPICo1989.8173B    Altcode:
  An Interstellar Probe Mission concept to the Interstellar Medium
  is discussed that would represent humanity's first explicit step
  scientifically, technologically, and programmatically to reach
  another star.

---------------------------------------------------------
Title: Predicting the Magnetic Field of Earth-impacting CMEs
Authors: Kay, C.; Gopalswamy, N.; Reinard, A.; Opher, M.
2017ApJ...835..117K    Altcode:
  Predicting the impact of coronal mass ejections (CMEs) and the southward
  component of their magnetic field is one of the key goals of space
  weather forecasting. We present a new model, the ForeCAT In situ Data
  Observer (FIDO), for predicting the in situ magnetic field of CMEs. We
  first simulate a CME using ForeCAT, a model for CME deflection and
  rotation resulting from the background solar magnetic forces. Using
  the CME position and orientation from ForeCAT, we then determine the
  passage of the CME over a simulated spacecraft. We model the CME’s
  magnetic field using a force-free flux rope and we determine the in
  situ magnetic profile at the synthetic spacecraft. We show that FIDO
  can reproduce the general behavior of four observed CMEs. FIDO results
  are very sensitive to the CME’s position and orientation, and we
  show that the uncertainty in a CME’s position and orientation from
  coronagraph images corresponds to a wide range of in situ magnitudes
  and even polarities. This small range of positions and orientations
  also includes CMEs that entirely miss the satellite. We show that two
  derived parameters (the normalized angular distance between the CME
  nose and satellite position and the angular difference between the
  CME tilt and the position angle of the satellite with respect to the
  CME nose) can be used to reliably determine whether an impact or miss
  occurs. We find that the same criteria separate the impacts and misses
  for cases representing all four observed CMEs.

---------------------------------------------------------
Title: How Numerical Magnetic Dissipation at the Heliospheric
    Current Sheet Affects Model Predictions at Voyager 1 and Results
    from a Kinetic-MHD Model of the Heliosphere within SWMF
Authors: Michael, A.; Opher, M.; Toth, G.; Borovikov, D.; Tenishev,
   V.; Provornikova, E.
2016AGUFMSH41C2544M    Altcode:
  Several studies suggest that there is a need to move beyond ideal MHD
  in order to explain the Voyager 1 and 2 observations (Richardson et
  al. 2013; Michael et al. 2015). In the numerical simulations there
  is inherent and unavoidable numerical dissipation in the heliospheric
  current sheet that greatly exceeds the realistic dissipation rates. The
  magnetic dissipation inherent in modeling the heliospheric current
  sheet offers us a chance to explore non-ideal MHD effects in the
  heliosphere and heliosheath. In this work we investigate the role
  magnetic dissipation has on the overall structure of the heliosheath
  by comparing models describing the solar magnetic field both as a
  unipole and a dipole. We show that magnetic dissipation reduces the
  solar wind magnetic field strength over a significant fraction of
  the heliosheath. The region affected by the dissipation is increased
  when 11-year solar cycle variations in the solar wind are included
  and we discuss how this alters our prediction for Voyager 1 and 2
  observations. We also present a new kinetic-MHD model of the outer
  heliosphere, which couples the Outer Heliosphere (OH) and Particle
  Tracker (PT) components within the Space Weather Modeling Framework
  (SWMF). The OH component uses the BATS-R-US MHD solver, a highly
  parallel, 3D, and block-adaptive code. The PT component is based on the
  Adaptive Mesh Particle Simulator (AMPS) model, a 3D, direct simulation
  Monte Carlo model that solves the Boltzmann equation for the motion and
  interaction of a multi-species gas within a plasma. The neutrals and
  plasma in the outer heliosphere are coupled through charge-exchange;
  the OH-PT model combines the MHD solution for the plasma with the
  kinetic solution for the neutrals to form a self-consistent model
  of the heliosphere. We present preliminary results of this model and
  discuss the implications on the structure of the heliosphere.

---------------------------------------------------------
Title: Probing the nature of pick-up ions (and kappa distribution)
    in the heliosheath through global ENA measurements and in-situ
    measurements
Authors: Opher, M.; Zieger, B.; Drake, J. F.; Kornbleuth, M. Z.;
   Toth, G.
2016AGUFMSH13D..01O    Altcode:
  Both Voyager and IBEX are providing us with an un-precedent view of
  the nature of the heliosheath through in situ and global ENA maps. Both
  their measurements indicated that the thermodynamic of the heliosheath
  is dominated by the presence of pick-up ions (PUIs). Kappa distributions
  are routinely used to capture the presence of PUIs. Recently we
  investigated the nature of the crossing of the termination shock
  by the presence of the pick-up ions (Zieger et al. 2015). We were
  able to constrain the properties of the PUI in the heliosheath by
  matching the Voyager observations to the properties of the non-linear
  structures created by the multi-fluid nature of the solar wind called
  "oscilliton". Here we will review these results as well as our recent
  effort on understanding the nature of the turbulence of the heliosheath
  by the presence of pick-up ions. We will review as well our recent
  proposed scenario where that the structure of the heliosphere might be
  very different than we previously thought (Opher et al. 2015). We showed
  (Opher et al. 2015, Drake et al. 2015) that the magnetic tension of the
  solar magnetic field plays a crucial role on organizing the solar wind
  in the heliosheath into two jet-like structures. The global ENA maps
  provide another window in constraining the pick-up ions and heating
  in the heliosheath (Opher et al. 2013). We will discuss the resultant
  maps from the "heliosphere with jets" and the constrains on the nature
  of the pick-up ions in the heliosheath.

---------------------------------------------------------
Title: Investigating the Effect of the Heliosphere with Jets on ENAs
    as a Function of Solar Cycle
Authors: Kornbleuth, M. Z.; Opher, M.; Michael, A.; Zieger, B.
2016AGUFMSH31A2535K    Altcode:
  The Interstellar Boundary Explorer (IBEX) and INCA, on board the Cassini
  spacecraft, have been probing the global structure of the heliosphere
  using energetic neutral atoms (ENAs). IBEX tail measurements show
  a latitudinal dependence in the ENA flux, where two lobes appear at
  high latitudes in higher energies (4 keV). These measurements were
  explained as being representative of the presence of the slow and fast
  wind (McComas et al. 2013). Recently, Opher et al. (2015) proposed
  that the heliosphere might have turbulent jets in its tail region,
  as opposed to the classically accepted quiescent, extended comet-like
  tail. This proposed model of the heliosphere has a "croissant-like"
  shape, suggesting the lobes seen by IBEX are a structural feature. Over
  a given solar cycle, the lobes seen by IBEX should evolve differently
  based on whether they are a result of the presence of slow/fast wind
  or if they are a structural feature of the heliosphere. If confirmed,
  the "croissant-like" heliosphere would significantly change our
  understanding of how the interstellar medium interacts with the
  solar wind. We investigate the effect of the solar cycle on the lobe
  structure of the heliosphere with jets model, and the resulting ENA
  maps using a multi-ion, multi-fluid model. We compare our results with
  observations from IBEX to assess the validity of the "croissant-like"
  model. We find that the jets produce ENA signatures consistent with
  IBEX measurements of the heliotail, where two lobes are visible in
  the northern and southern hemispheres (McComas et al. 2013; Schwadron
  et al. 2014). The jets are associated with a strong ENA flux around 4
  keV, while the interstellar medium flowing between the jets generates
  a lower ENA flux at this IBEX energy band.

---------------------------------------------------------
Title: Dispersive Magnetosonic Waves and Turbulence in the
Heliosheath: Multi-Fluid MHD Reconstruction of Voyager 2 Observations
Authors: Zieger, B.; Opher, M.; Toth, G.
2016AGUFMSH41C2542Z    Altcode:
  Recently we demonstrated that our three-fluid MHD model of the solar
  wind plasma (where cold thermal solar wind ions, hot pickup ions, and
  electrons are treated as separate fluids) is able to reconstruct the
  microstructure of the termination shock observed by Voyager 2 [Zieger
  et al., 2015]. We constrained the unknown pickup ion abundance and
  temperature and confirmed the presence of a hot electron population at
  the termination shock, which has been predicted by a number of previous
  theoretical studies [e.g. Chasei and Fahr, 2014; Fahr et al., 2014]. We
  showed that a significant part of the upstream hydrodynamic energy is
  transferred to the heating of pickup ions and "massless" electrons. As
  shown in Zieger et al., [2015], three-fluid MHD theory predicts two
  fast magnetosonic modes, a low-frequency fast mode or solar wind ion
  (SW) mode and a high-frequency fast mode or pickup ion (PUI) mode. The
  coupling of the two ion populations results in a quasi-stationary
  nonlinear mode or oscilliton, which appears as a trailing wave
  train downstream of the termination shock. In single-fluid plasma,
  dispersive effects appear on the scale of the Debye length. However,
  in a non-equilibrium plasma like the solar wind, where solar wind
  ions and PUIs have different temperatures, dispersive effects become
  important on fluid scales [see Zieger et al., 2015]. Here we show that
  the dispersive effects of fast magnetosonic waves are expected on the
  scale of astronomical units (AU), and dispersion plays an important
  role producing compressional turbulence in the heliosheath. The
  trailing wave train of the termination shock (the SW-mode oscilliton)
  does not extend to infinity. Downstream propagating PUI-mode waves
  grow until they steepen into PUI shocklets and overturn starting to
  propagate backward. The upstream propagating PUI-mode waves result
  in fast magnetosonic turbulence and limit the downstream extension of
  the oscilliton. The overturning distance of the PUI-mode, where these
  waves start to propagate backward, depends on the maximum growth rate
  of the PUI-mode. We discuss our simulations in light of the Voyager
  2 observations in the heliosheath.

---------------------------------------------------------
Title: Multi-ion Multi-fluid Simulations of the Effects of Pick-up
    Ions on the Global Structure of the Heliosphere
Authors: Bambic, C. J.; Opher, M.; Zieger, B.; Michael, A.; Kornbleuth,
   M. Z.; Toth, G.
2016AGUFMSH41C2543B    Altcode:
  We present the first 3D MHD multi-ion, multi-fluid simulations
  including pick-up ions as a separate fluid on the global structure of
  the heliosphere. Pick-up ions, formed by charge exchange between the
  solar wind and local interstellar medium, are thought to account for
  the missing thermal energy measured by Voyager 2 at the crossing of the
  Termination Shock. By treating the pick-up ions as a separate fluid
  (with an isotropic distribution) from the solar wind thermal plasma,
  we are able to isolate the properties of the suprathermal pick-up
  ion plasma from that of the thermal solar wind. In addition to the
  two charged ion fluids, we include four neutral fluids which interact
  via charge exchange with the pick-up ion plasma. We show that pick-up
  ions are dynamically important in the outer heliosphere, thinning and
  heating the heliosheath. Since the neutral fluids are imprinted with the
  properties of the plasma they are born from, this work has implications
  for the Energetic Neutral Atom (ENA) maps of the global heliosphere. We
  discuss briefly the effects on the global ENA maps of the heliosphere
  in addition to measurements along the Voyager 1 and 2 trajectories.

---------------------------------------------------------
Title: Turbulence in the Heliospheric Jets
Authors: Drake, J. F.; Swisdak, M.; Opher, M.; Hassam, A.; Ohia, O.
2016AGUFMSH31A2536D    Altcode:
  The conventional picture of the heliosphere is that of a comet-shaped
  structure with an extended tail produced by the relative motion
  of the sun through the local interstellar medium (LISM). Recent MHD
  simulations of the global heliosphere have revealed, however, that the
  heliosphere drives magnetized jets to the North and South similar to
  those driven by the Crab Nebula and other astrophysical objects. These
  simulations reveal that the jets become turbulent with scale lengths
  as large as 100AU [1,2]. An important question is what drives this
  large-scale turbulence, what are the implications for mixing of
  interstellar and heliospheric plasma and does this turbulence drive
  energetic particles? An analytic model of the heliospheric jets in
  the simple limit in which the interstellar flow and magnetic field
  are neglected yields an equilibrium state that can be analyzed
  to explore potential instabilities [3]. Calculations suggest that
  because the axial magnetic field within the jets is small, the dominant
  instability is the sausage mode, driven by the azimuthal solar magnetic
  field. Other drive mechanisms, including Kelvin Helmholtz, are also
  being explored. 3D MHD and Hall MHD simulations are being carried out
  to explore the development of this turbulence, its impact on the mixing
  of interstellar and heliosheath plasma and the production of energetic
  particles. [1] Opher et al ApJ Lett. 800, L28, 2015[2] Pogorelov et
  al ApJ Lett. 812,L6, 2015[3] Drake et al ApJ Lett. 808, L44, 2015

---------------------------------------------------------
Title: The ForeCAT In Situ Data Observer and the Effects of Deflection
    and Rotation on CME Geoeffectiveness
Authors: Kay, C.; Gopalswamy, N.; Reinard, A.; Opher, M.;
   Nieves-Chinchilla, T.
2016AGUFMSH13B2298K    Altcode:
  CMEs drive the strongest space weather events at Earth and throughout
  the solar system. At Earth, the amount of southward magnetic field in a
  CME is a major component in determining the severity of an impact. We
  present results from ForeCAT (Forecasting a CME's Altered Trajectory,
  Kay et al. 2015), which predicts the deflection and rotation of
  CMEs based on magnetic forces determined by the background magnetic
  field. Understanding these deflections and rotations is essential to
  understanding the geoeffectiveness of CMEs as it determines whether a
  CME will hit Earth and the orientation of the flux rope magnetic field
  upon impact. Using the CME location and orientation from ForeCAT and
  simple flux rope models we show that we can reproduce the in situ
  magnetic profiles of Earth-impacting CMEs with the new ForeCAT In
  situ Data Observer (FIDO). We compare these results with the in situ
  profiles obtained assuming that no deflection or rotation occurs, and
  find that including these nonradial effects is essential for accurate
  space weather forecasting. For several observed cases we comment on
  how the deflection and rotation affects the southward component of
  the CME's magnetic field, and therefore the CME's geoeffectiveness.

---------------------------------------------------------
Title: The Heliosphere with Jets and its implications for the global
    Energetic Neutral Atoms Maps throughout the Solar Cycle and its
    impact on the large-scale draping of the interstellar magnetic field
Authors: Opher, M.; Drake, J. F.; Kornbleuth, M. Z.; Michael, A.;
   Zieger, B.; Swisdak, M.; Toth, G.
2016AGUFMSH23A..05O    Altcode:
  Recently we proposed a scenario (Opher et al. 2015) that the
  structure of the heliosphere might be very different than we previously
  thought. The standard picture of the heliosphere is a comet-shape like
  structure with the tail extending for 1000's of AUs. This standard
  picture stems from a view where magnetic forces are negligible and the
  solar magnetic field is convected passively down the tail. We showed
  (Opher et al. 2015, Drake et al. 2015) that the magnetic tension
  of the solar magnetic field plays a crucial role on organizing the
  solar wind in the heliosheath into two jet-like structures. The two
  heliospheric jets are separated by the interstellar medium that
  flows between them. The heliosphere then has a “croissant"-like
  shape where the distance to the heliopause downtail is almost the
  same as towards the nose. Here we present the implications of this
  "croissant-like structure" for the global Energetic Neutral Atoms
  maps as measured by IBEX in the heliotail and its variation with
  solar cycle. We include solar cycle variations of the solar wind
  (density and speed and magnetic intensity) while keeping a unipolar
  configuration to minimize spurious magnetic dissipation that erodes
  the solar magnetic field. We discuss as well the consequences on the
  draping and reconnection of the interstellar magnetic field across the
  heliopause. We show that reconnection in the flanks and tail control the
  draping and the orientation of the interstellar magnetic field (BISM)
  ahead of the heliopause and can explain the Voyager 1 observations. The
  BISM twists as it approaches the HP and acquires a strong T component
  (East-West) as shown in Opher &amp; Drake (2013). Only after some
  significant distance outside the HP is the direction of the interstellar
  field distinguishably different from that of the Parker spiral.

---------------------------------------------------------
Title: Voyager Observations of Magnetic Sectors and Heliospheric
    Current Sheet Crossings in the Outer Heliosphere
Authors: Richardson, J. D.; Burlaga, L. F.; Drake, J. F.; Hill, M. E.;
   Opher, M.
2016ApJ...831..115R    Altcode:
  Voyager 1 (V1) has passed through the heliosheath and is in the local
  interstellar medium. Voyager 2 (V2) has been in the heliosheath since
  2007. The role of reconnection in the heliosheath is under debate;
  compression of the heliospheric current sheets (HCS) in the heliosheath
  could lead to rapid reconnection and a reconfiguration of the magnetic
  field topology. This paper compares the expected and actual amounts
  of time the Voyager spacecraft observe each magnetic sector and the
  number of HCS crossings. The predicted and observed values generally
  agree well. One exception is at Voyager 1 in 2008 and 2009, where the
  distribution of sectors is more equal than expected and the number of
  HCS crossings is small. Two other exceptions are at V1 in 2011-2012 and
  at V2 in 2012, when the spacecraft are in the opposite magnetic sector
  less than expected and see fewer HCS crossings than expected. These
  features are consistent with those predicted for reconnection, and
  consequently searches for other reconnection signatures should focus
  on these times.

---------------------------------------------------------
Title: Determining ICME Magnetic Field Orientation with the ForeCAT
    In Situ Data Observer
Authors: Kay, Christina; Gopalswamy, N.; Reinard, A.; Opher, M.
2016usc..confE..20K    Altcode:
  CMEs drive the strongest space weather events at Earth and throughout
  the solar system. At Earth, the amount of southward magnetic field in a
  CME is a major component in determining the severity of an impact. We
  present results from ForeCAT (Forecasting a CME's Altered Trajectory,
  Kay et al. 2015), which predicts the deflection and rotation of
  CMEs based on magnetic forces determined by the background magnetic
  field. Using HMI magnetograms to reconstruct the background magnetic
  field and AIA images to constrain the early evolution of CMEs, we show
  that we can reproduce the deflection and rotation of CMEs observed
  in the corona. Using this CME location and orientation from ForeCAT
  results and a simple force-free flux rope model we show that we can
  reproduce the in situ magnetic profiles of Earth-impacting CMEs. We
  compare these results with the in situ profiles obtained assuming
  that no deflection or rotation occurs, and find that including these
  nonradial effects is essential for accurate space weather forecasting.

---------------------------------------------------------
Title: Using ForeCAT Deflections and Rotations to Constrain the
    Early Evolution of CMEs
Authors: Kay, C.; Opher, M.; Colaninno, R. C.; Vourlidas, A.
2016ApJ...827...70K    Altcode: 2016arXiv160603460K
  To accurately predict the space weather effects of the impacts of
  coronal mass ejection (CME) at Earth one must know if and when a CME
  will impact Earth and the CME parameters upon impact. In 2015 Kay et
  al. presented Forecasting a CME’s Altered Trajectory (ForeCAT),
  a model for CME deflections based on the magnetic forces from the
  background solar magnetic field. Knowing the deflection and rotation of
  a CME enables prediction of Earth impacts and the orientation of the
  CME upon impact. We first reconstruct the positions of the 2010 April
  8 and the 2012 July 12 CMEs from the observations. The first of these
  CMEs exhibits significant deflection and rotation (34° deflection
  and 58° rotation), while the second shows almost no deflection or
  rotation (&lt;3° each). Using ForeCAT, we explore a range of initial
  parameters, such as the CME’s location and size, and find parameters
  that can successfully reproduce the behavior for each CME. Additionally,
  since the deflection depends strongly on the behavior of a CME in the
  low corona, we are able to constrain the expansion and propagation of
  these CMEs in the low corona.

---------------------------------------------------------
Title: Probability of CME Impact on Exoplanets Orbiting M Dwarfs
    and Solar-like Stars
Authors: Kay, C.; Opher, M.; Kornbleuth, M.
2016ApJ...826..195K    Altcode: 2016arXiv160502683K
  Solar coronal mass ejections (CMEs) produce adverse space weather
  effects at Earth. Planets in the close habitable zone of magnetically
  active M dwarfs may experience more extreme space weather than at
  Earth, including frequent CME impacts leading to atmospheric erosion
  and leaving the surface exposed to extreme flare activity. Similar
  erosion may occur for hot Jupiters with close orbits around solar-like
  stars. We have developed a model, Forecasting a CME's Altered Trajectory
  (ForeCAT), which predicts a CME's deflection. We adapt ForeCAT to
  simulate CME deflections for the mid-type M dwarf V374 Peg and hot
  Jupiters with solar-type hosts. V374 Peg's strong magnetic fields can
  trap CMEs at the M dwarfs's Astrospheric Current Sheet, that is, the
  location of the minimum in the background magnetic field. Solar-type
  CMEs behave similarly, but have much smaller deflections and do not
  become trapped at the Astrospheric Current Sheet. The probability
  of planetary impact decreases with increasing inclination of the
  planetary orbit with respect to the Astrospheric Current Sheet: 0.5-5
  CME impacts per day for M dwarf exoplanets, 0.05-0.5 CME impacts per
  day for solar-type hot Jupiters. We determine the minimum planetary
  magnetic field necessary to shield a planet's atmosphere from CME
  impacts. M dwarf exoplanets require values between tens and hundreds
  of Gauss. Hot Jupiters around a solar-type star, however, require a
  more reasonable &lt;30 G. These values exceed the magnitude required
  to shield a planet from the stellar wind, suggesting that CMEs may be
  the key driver of atmospheric losses.

---------------------------------------------------------
Title: Effects of Numerical Magnetic Dissipation on the
    Characteristics of the Heliosphere
Authors: Michael, Adam Thomas; Opher, Merav; Provornikova, Elena;
   Toth, Gabor
2016shin.confE.125M    Altcode:
  Through the use of numerical models, we have recently begun to
  realize the importance the solar wind"s magnetic field has on the
  location of the termination shock (Izmodenov and Alexashov 2015)
  as well as the shape of the heliosphere (Opher et al. 2015) and
  thickness of the heliosheath (Drake et al. 2015). Several studies
  suggest that there should be a need to move beyond ideal MHD in order
  to explain the Voyager 1 and 2 observations (Richardson et al. 2013;
  Michael et al. 2015). In the numerical simulations there is inherent
  numerical dissipation in the helispheric current sheet that an ideal
  MHD model cannot control. In a sense the dissipated magnetic energy
  can be transferred to thermal heating or to ram pressure. The magnetic
  dissipation inherent in modeling the heliospheric current sheet offers
  us a chance to explore non-ideal MHD effects in the heliosphere
  and heliosheath. Solar cycle models that include the reversal of
  the magnetic field have inherently a large fraction of magnetic
  dissipation. In this work we investigate the role magnetic dissipation
  has on the overall structure of the heliosheath. We describe the solar
  magnetic field both as a dipole, with the magnetic and rotational axes
  aligned, as well as a unipole. We have seen in Opher et al. 2016 that
  the use of a dipole magnetic field, in the case without any motion
  through the ISM, reduces the confinement of the plasma at the current
  sheet. We investigate how the magnetic dissipation affects the shape and
  thickness of the heliosheath and heliosphere. Furthermore, we explore
  how these effects are altered when 11-year solar cycle variations in
  the solar wind are included and comment on how magnetic dissipation
  alters the prediction for Voyager 1 and 2 observations.

---------------------------------------------------------
Title: Investigating the Effect of the 'Croissant-like' Heliosphere
    on ENAs
Authors: Kornbleuth, Marc Zachary; Opher, Merav; Zieger, Bertalan
2016shin.confE.124K    Altcode:
  The Interstellar Boundary Explorer (IBEX) and Cassini spacecraft
  have been probing the global structure of the heliosphere using
  energetic neutral atoms (ENAs). Recently, Opher et al. (2015)
  proposed that the heliosphere may have turbulent jets in its
  tail region, as opposed to the classically accepted quiescent,
  extended comet-like tail. This proposed model of the heliosphere
  is considered to have a 'croissant-like' shape. We investigate the
  effect of the 'croissant-like' heliosphere on ENA maps. Here we
  present preliminary results of the globally distributed ENA flux and
  compare with observations (Schwadron et al. 2014). We assume a kappa
  distribution for the plasma in the heliosheath (Prested et al. 2008)
  and a Maxwellian distribution for the plasma in the interstellar
  medium. We find that the jets produce an ENA signature consistent with
  IBEX measurements of the heliotail (McComas et al. 2013; Schwadron et
  al. 2014). Future studies will investigate the evolution of the jets
  with solar cycle and their signature in ENAs.

---------------------------------------------------------
Title: The deflection of the 'Cartwheel' CME: ForeCAT results
Authors: Capannolo, Luisa; Opher, M.; Kay, C. C.; Landi, E.
2016shin.confE..48C    Altcode:
  Coronal Mass Ejections (CMEs) are of high scientific interest as
  they represent the major cause of geomagnetic activity at Earth. In
  this work, we examine the CME that occurred on April 9th, 2008,
  during the solar minimum of solar cycle 24. This CME is referred to
  as the 'Cartwheel CME' due to its unusual motion in the coronagraph
  observations: the CME clearly rotates as it propagates outward. The CME
  also shows a reversal in its latitudinal direction: the CME is ejected
  at -20 degrees and moves southward to -30 degrees, then turns and
  deflects northward to -20 degrees until it begins propagating radially
  at 5-6 solar radii. Longitudinally, the CME is essentially stable. We
  model the trajectory of the CME in the low corona with the ForeCAT model
  (Kay et al., 2013; Kay et al., 2015). ForeCAT is based on magnetic
  forces that act on CMEs as they propagate in the solar wind. Given a
  magnetic background and initial parameters, ForeCAT provides the CME
  trajectory, including any deflection or rotation, as a function of
  time and distance from the Sun. We compare the results of the model
  to available data of latitude and longitude of the CME (Landi et al.,
  2010). ForeCAT successfully predicts the reversal in the latitudinal
  deflection of the Cartwheel CME. To match the data, we constrain the
  initial mass of the CME to 3.5 10^14 g in the low corona, the initial
  CME size and the angular width expansion law of the CME (linear as a
  function of distance until 2.10 solar radii and constant onwards).

---------------------------------------------------------
Title: Voyager 2 solar plasma and magnetic field spectral analysis
    for intermediate data sparsity
Authors: Gallana, Luca; Fraternale, Federico; Iovieno, Michele;
   Fosson, Sophie M.; Magli, Enrico; Opher, Merav; Richardson, John D.;
   Tordella, Daniela
2016JGRA..121.3905G    Altcode: 2015arXiv151004304G
  The Voyager probes are the furthest, still active, spacecraft ever
  launched from Earth. During their 38 year trip, they have collected
  data regarding solar wind properties (such as the plasma velocity and
  magnetic field intensity). Unfortunately, a complete time evolution
  of the measured physical quantities is not available. The time series
  contains many gaps which increase in frequency and duration at larger
  distances. The aim of this work is to perform a spectral and statistical
  analysis of the solar wind plasma velocity and magnetic field using
  Voyager 2 data measured in 1979, when the gap density is between the
  30% and 50%. For these gap densities, we show the spectra of gapped
  signals inherit the characteristics of the data gaps. In particular, the
  algebraic decay of the intermediate frequency range is underestimated
  and discrete peaks result not from the underlaying data but from the gap
  sequence. This analysis is achieved using five different data treatment
  techniques coming from the multidisciplinary context: averages on
  linearly interpolated subsets, correlation without data interpolation,
  correlation of linearly interpolated data, maximum likelihood data
  reconstruction, and compressed sensing spectral estimation. With five
  frequency decades, the spectra we obtained have the largest frequency
  range ever computed at five astronomical units from the Sun; spectral
  exponents have been determined for all the components of the velocity
  and magnetic field fluctuations. Void analysis is also useful in
  recovering other spectral properties such as micro and integral scales.

---------------------------------------------------------
Title: ForeCAT - A Model for Magnetic Deflections of Coronal Mass
    Ejections
Authors: Kay, Christina; Opher, Merav
2016SPD....4710303K    Altcode:
  Accurate space weather forecasting requires knowledge of the trajectory
  of CMEs. Decades of observations show that CMEs can deflect from a
  purely radial trajectory, however, no consensus exists as to the cause
  of these deflections. We developed a model for CME deflection and
  rotation from magnetic forces, called Forecasting a CME’s Altered
  Trajectory (ForeCAT). ForeCAT has been designed to run fast enough
  for large parameter phase space studies, and potentially real-time
  predictions.ForeCAT reproduces the general trends seen in observed
  CME deflections. In particular, CMEs deflect toward regions of minimum
  magnetic energy - frequently the Heliospheric Current Sheet (HCS) on
  global scales. The background magnetic forces decrease rapidly with
  distance and quickly become negligible. Most deflections and rotations
  can be well-described by assuming constant angular momentum beyond
  10 Rs.ForeCAT also reproduces individual observed CME deflections
  - the 2008 December 12, 2008 April 08, and 2010 July 12 CMEs. By
  determining the reduced chi-squared best fit between the ForeCAT
  results and the observations we constrain parameters related to the
  CME and the background solar wind. Additionally, we constrain whether
  different models for the low corona magnetic backgrounds can produce
  the observed CME deflection.

---------------------------------------------------------
Title: The Heliosphere: What Did We Learn in Recent Years and the
    Current Challenges
Authors: Opher, M.
2016SSRv..200..475O    Altcode: 2015SSRv..tmp...80O
  No abstract at ADS

---------------------------------------------------------
Title: Turbulence in the solar wind: spectra from Voyager 2 data at
    5 AU
Authors: Fraternale, F.; Gallana, L.; Iovieno, M.; Opher, M.;
   Richardson, J. D.; Tordella, D.
2016PhyS...91b3011F    Altcode: 2015arXiv150207114F
  Fluctuations in the flow velocity and magnetic fields are ubiquitous
  in the Solar System. These fluctuations are turbulent, in the sense
  that they are disordered and span a broad range of scales in both space
  and time. The study of solar wind turbulence is motivated by a number
  of factors all keys to the understanding of the Solar Wind origin
  and thermodynamics. The solar wind spectral properties are far from
  uniformity and evolve with the increasing distance from the sun. Most
  of the available spectra of solar wind turbulence were computed at 1
  astronomical unit, while accurate spectra on wide frequency ranges at
  larger distances are still few. In this paper we consider solar wind
  spectra derived from the data recorded by the Voyager 2 mission during
  1979 at about 5 AU from the sun. Voyager 2 data are an incomplete
  time series with a voids/signal ratio that typically increases as the
  spacecraft moves away from the sun (45% missing data in 1979), making
  the analysis challenging. In order to estimate the uncertainty of the
  spectral slopes, different methods are tested on synthetic turbulence
  signals with the same gap distribution as V2 data. Spectra of all
  variables show a power law scaling with exponents between -2.1 and -1.1,
  depending on frequency subranges. Probability density functions (PDFs)
  and correlations indicate that the flow has a significant intermittency.

---------------------------------------------------------
Title: Conditions for the existence of Kelvin-Helmholtz instability
    in a CME
Authors: Páez, Andrés; Jatenco-Pereira, Vera; Falceta-Gonçcalves,
   Diego; Opher, Merav
2016IAUS..320..218P    Altcode:
  The presence of Kelvin-Helmholtz instability (KHI) in the sheaths
  of Coronal Mass Ejections (CMEs) has been proposed and observed by
  several authors in the literature. In the present work, we assume
  their existence and propose a method to constrain the local properties,
  like the CME magnetic field intensity for the development of KHI. We
  study a CME in the initiation phase interacting with the slow solar
  wind (Zone I) and with the fast solar wind (Zone II). Based on the
  theory of magnetic KHI proposed by Chandrasekhar (1961) we found the
  radial heliocentric interval for the KHI existence, in particular we
  constrain it with the CME magnetic field intensity. We conclude that
  KHI may exist in both CME Zones but it is perceived that Zone I is
  more appropriated for the KHI formation.

---------------------------------------------------------
Title: Cross and magnetic helicity in the outer heliosphere from
    Voyager 2 observations
Authors: Iovieno, M.; Gallana, L.; Fraternale, F.; Richardson, J. D.;
   Opher, M.; Tordella, D.
2016EJMF...55..394I    Altcode: 2015arXiv150408154I
  Plasma velocity and magnetic field measurements from the Voyager 2
  mission are used to study solar wind turbulence in the slow solar wind
  at two different heliocentric distances, 5 and 29 astronomical units,
  sufficiently far apart to provide information on the radial evolution
  of this turbulence. The magnetic helicity and the cross-helicity,
  which express the correlation between the plasma velocity and the
  magnetic field, are used to characterize the turbulence. Wave number
  spectra are computed by means of the Taylor hypothesis applied to time
  resolved single point Voyager 2 measurements. The overall picture we get
  is complex and difficult to interpret. A substantial decrease of the
  cross-helicity at smaller scales (over 1-3 hours of observation) with
  increasing heliocentric distance is observed. At 5 AU the only peak in
  the probability density of the normalized residual energy is negative,
  near -0.5. At 29 AU the probability density becomes doubly peaked,
  with a negative peak at -0.5 and a smaller peak at a positive values of
  about 0.7. A decrease of the cross-helicity for increasing heliocentric
  distance is observed, together with a reduction of the unbalance toward
  the magnetic energy of the energy of the fluctuations. For the smaller
  scales, we found that at 29 AU the normalized polarization is small and
  positive on average (about 0.1), it is instead zero at 5 AU. For the
  larger scales, the polarization is low and positive at 5 AU (average
  around 0.1) while it is negative (around - 0.15) at 29 AU.

---------------------------------------------------------
Title: The Heliosphere: What Did We Learn in Recent Years and the
    Current Challenges
Authors: Opher, M.
2016mssf.book..211O    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Solar Wind Prediction at Pluto During the New Horizons Flyby:
    Results From a Two-Dimensional Multi-fluid MHD Model of the Outer
    Heliosphere
Authors: Zieger, B.; Toth, G.; Opher, M.; Gombosi, T. I.
2015AGUFMSM31D2539Z    Altcode:
  We adapted the outer heliosphere (OH) component of the Space Weather
  Modeling Framework, which is a 3-D global multi-fluid MHD model of the
  outer heliosphere with one ion fluid and four neutral populations, for
  time-dependent 2-D multi-fluid MHD simulations of solar wind propagation
  from a heliocentric distance of 1 AU up to 50 AU. We used this model to
  predict the solar wind plasma parameters as well as the interplanetary
  magnetic field components at Pluto and along the New Horizons trajectory
  during the whole calendar year of 2015 including the closest approach
  on July 14. The simulation is run in the solar equatorial plane in the
  heliographic inertial frame (HGI). The inner boundary conditions along
  a circle of 1 AU radius are set by near-Earth solar wind observations
  (hourly OMNI data), assuming that the global solar wind distribution
  does not change much during a Carrington rotation (27.2753 days). Our
  2-D multi-fluid MHD code evolves one ion fluid and two neutral fluids,
  which are the primary interstellar neutral atoms and the interstellar
  neutral atoms deflected in the outer heliosheath between the slow bow
  shock and the heliopause. Spherical expansion effects are properly
  taken into account for the ions and the solar magnetic field. The
  inflow parameters of the two neutral fluids (density, temperature,
  and velocity components) are set at the negative X (HGI) boundary at 50
  AU distance, which are taken from previous 3-D global multi-fluid MHD
  simulations of the heliospheric interface in a much larger simulation
  box (1500x1500x1500 AU). The inflow velocity vectors of the two neutral
  fluids define the so-called hydrogen deflection plane. The solar wind
  ions and the interstellar neutrals interact through charge exchange
  source terms included in the multi-fluid MHD equations, so the two
  neutral populations are evolved self-consistently. We validate our
  model with the available plasma data from New Horizons as well as
  with Voyager 2 plasma and magnetic field observations within the
  heliocentric distance of 50 AU. Our new time-dependent 2-D multi-fluid
  MHD model is generally applicable for solar wind predictions at any
  outer planet (Jupiter, Saturn, Uranus, Neptune) or spacecraft in the
  outer heliosphere where charge exchange between solar wind ions and
  interstellar neutrals play an important role.

---------------------------------------------------------
Title: Using the 11-year Solar Cycle to Predict the Heliosheath
    Environment at Voyager 1 and 2
Authors: Michael, A.; Opher, M.; Provornikova, E.; Richardson, J. D.;
   Toth, G.
2015AGUFMSH41A2373M    Altcode:
  As Voyager 2 moves further into the heliosheath, the region of subsonic
  solar wind plasma in between the termination shock and the heliopause,
  it has observed an increase of the magnetic field strength to large
  values, all while maintaining magnetic flux conservation. Dr. Burlaga
  will present these observations in the 2015 AGU Fall meeting
  (abstract ID: 59200). The increase in magnetic field strength could
  be a signature of Voyager 2 approaching the heliopause or, possibly,
  due to solar cycle effects. In this work we investigate the role the
  11-year solar cycle variations as well as magnetic dissipation effects
  have on the heliosheath environments observed at Voyager 1 and 2 using
  a global 3D magnetohydrodynamic model of the heliosphere. We use time
  and latitude-dependent solar wind velocity and density inferred from
  SOHO/SWAN and IPS data and solar cycle variations of the magnetic
  field derived from 27-day averages of the field magnitude average
  of the magnetic field at 1 AU from the OMNI database as presented in
  Michael et al. (2015). Since the model has already accurately matched
  the flows and magnetic field strength at Voyager 2 until 93 AU,
  we extend the boundary conditions to model the heliosheath up until
  Voyager 2 reaches the heliopause. This work will help clarify if the
  magnetic field observed at Voyager 2 should increase or decrease
  due to the solar cycle. We describe the solar magnetic field both
  as a dipole, with the magnetic and rotational axes aligned, and as
  a monopole, with magnetic field aligned with the interstellar medium
  to reduce numerical reconnection within the heliosheath, due to the
  removal of the heliospheric surrent sheet, and at the solar wind -
  interstellar medium interface. A comparison of the models allows for
  a crude estimation of the role that magnetic dissipation plays in the
  system and whether it allows for a better understanding of the Voyager
  2 location in the heliosheath.

---------------------------------------------------------
Title: A Model of the Heliosphere with Jets
Authors: Drake, J. F.; Swisdak, M.; Opher, M.
2015AGUFMSH53C..02D    Altcode:
  The conventional picture of the heliosphere is that of a comet-shaped
  structure with an extended tail produced by the relative motion of the
  sun through the local interstellar medium (LISM). On the other hand,
  the measurements of energetic neutral atoms (ENAs) by IBEX and CASSINI
  produced some surprises. The CASSINI ENA fluxes from the direction of
  the nose and the tail were comparable, leading the CASSINI observers to
  conclude that the heliosphere was “tailless”. The IBEX observations
  from the tail revealed that the hardest spectrum of ENAs were localized
  in two lobes at high latitude while the softest spectra were at low
  latitudes. Recent MHD simulations of the global heliosphere have
  revealed that the heliosphere drives magnetized jets to the north and
  south similar to those driven by the Crab Nebula and other astrophysical
  objects [1]. That the sun's magnetic field can drive such jets when the
  magnetic pressure in the outer heliosphere is small compared with the
  local plasma pressure (β=8∏ P/B2 &gt;&gt; 1) is a major surprise. An
  analytic model of the heliosheath (HS) between the termination shock
  (TS) and the heliopause (HP) is developed in the limit in which the
  interstellar flow and magnetic field are neglected [2]. The heliosphere
  in this limit is axisymmetric. The overall structure of the HS and
  HP are controlled by the solar magnetic field even in the limit of
  very high β because the large pressure in the HS is to lowest order
  balanced by the pressure of the LISM. The tension of the solar magnetic
  field produces a drop in the total pressure between the TS and the
  HP. This same pressure drop accelerates the plasma flow downstream
  of the TS into the north and south directions to form two collimated
  jets. The radii of these jets are controlled by the flow through the TS
  and the acceleration of this flow by the magnetic field -- a stronger
  solar magnetic field boosts the velocity of the jets and reduces the
  radii of the jets and the HP. Magnetohydrodynamic (MHD) simulations
  of the global helioshere embedded in a stationary interstellar medium
  match well with the analytic model. The possbility of testing the jet
  model of the heliosphere using energetic neutral atoms from the outer
  heliosphere from IBEX and CASSINI is discussed. [1] Opher et al ApJ
  Lett. 800, L28, 2015.[2] Drake et al ApJ Lett., in press, 2015.

---------------------------------------------------------
Title: At What Distance are CME Deflections Determined?
Authors: Opher, M.; Kay, C.
2015AGUFMSH53A2461O    Altcode:
  Understanding the trajectory of a coronal mass ejection (CME), including
  any deflection from a radial path, is essential for space weather
  predictions. Kay et al. (2015a) developed a model, Forecasting a CME's
  Altered Trajectory (ForeCAT), of CME deflections due to magnetic forces,
  not including the effects of reconnection. ForeCAT is able to reproduce
  the deflection of observed CMEs (Kay et al. 2015b). The deflecting
  CMEs tend to show a rapid increase of their angular momentum close to
  the Sun, followed by little to no increase at farther distances. Here
  we quantify the distance at which the CME deflection is "determined,"
  which we define as the distance after which the background solar wind
  has negligible influence on the total deflection. We consider a wide
  range in CME masses and radial speeds and determine that the majority
  of simulated CMEs obtain 90% of their total angular momentum at 1
  AU below 2 Rs. The deflection of these CMEs can be well-described
  by assuming they propagate with constant angular momentum beyond 10
  Rs. The assumption of constant angular momentum beyond 10 Rs yields
  underestimates of the total deflection at 1 AU of only 5% to 10%. Since
  the deflection from magnetic forces is determined by 10 Rs, non-magnetic
  forces must be responsible for any observed interplanetary deflections
  where the CME has increasing angular momentum.

---------------------------------------------------------
Title: Magnetic flux annihilation and the development of magnetic
    field depletions in the sectored heliosheath
Authors: Drake, J. F.; Swisdak, M.; Opher, M.
2015AGUFMSH41C2391D    Altcode:
  The dynamics of magnetic reconnection in the sectored heliosheath
  isexplored with the goal of identifying signatures that can be
  comparedwith Voyager observations. Simulations now include much
  more realisticinitial conditions, including unequal magnetic
  fluxes in adjacentsectors and very high β. Large numbers of small
  magnetic islandsform early but rapidly coalesce to sector-size
  structures. Thelate-time magnetic structure of the sector zone
  differs greatly fromthat obtained in earlier simulations. Bands of
  unreconnected azimuthalmagnetic flux thread through the simulation
  domain separating regionsof depleted magnetic field strength. The
  depletion regions have radialscale sizes somewhat greater than the
  initial sector width. Theboundaries of the magnetic depletions are
  sharp and reveal littlechange in the direction of B. The characteristic
  minima of thedepletions are one third of the initial magnetic field
  strength. Atlate time surviving magnetic islands are widely spaced
  and occur inpairs. Cuts across the domain in the radial direction
  reveal mostlyunipolar flux except when a cut crosses one of the
  remnant magneticislands. This unusual late time magnetic structure
  is generic resultof reconnection in a high β system. The magnetic
  depletionsexhibit many of the properties of “proton boundary layers”
  seen inthe Voyager 1 magnetic field data. The simulations suggest
  that significant flux loss should take place in the heliosheath,
  which is consistent with Voyager measurements. The long periods of
  unipolar fluxseen by Voyager 1 prior to crossing the heliopause likely
  results fromthe annihilation of the sectors rather than an exit from
  the sectorzone.

---------------------------------------------------------
Title: Using ForeCAT to constrain the initial parameters of the 2010
    August 14 CME in the low corona.
Authors: Opher, M.; Pisharody, V. A.; Kay, C.
2015AGUFMSH53A2462O    Altcode:
  Forecasting a CME's Altered Trajectory (ForeCAT) is a model of the
  trajectory of coronal mass ejections (CMEs) (Kay et al. (2013,
  2015)). ForeCAT models a CME as a torus, calculates magnetic
  pressure and tension forces and drag at grid points along the CME,
  and integrates these forces to calculate a complete trajectory. To do
  so, ForeCAT must assume models of CME mass and size evolution. Kay
  et al. (2015b) demonstrated that when approximating CME mass as
  constant and using observed angular widths to determine CME size
  evolution, ForeCAT successfully replicates the observed trajectory
  of the 2008 December 12 CME. Here, we use ForeCAT to replicate the
  observed trajectory of the 2010 August 14 CME assuming constant mass
  and constant angular width. We also find that ForeCAT can reproduce the
  observed trajectory when we assume an increasing mass with distance as
  the CME propagates, and when assuming a changing angular width. Under
  each of these assumptions, we calculate the reduced chi-squared between
  simulated and observed latitudes to constrain CME parameters such as
  drag coefficient, initial latitude and longitude, and initial speed
  of the CME. With this exploration we show that ForeCAT can constrain
  tightly the initial parameters of the CME in the low corona.

---------------------------------------------------------
Title: Magnetized Jets Driven by the Sun, the Structure of the
Heliosphere Revisited: Consequences for Draping of BISM ahead of
    the HP and Time Variability of ENAs
Authors: Opher, M.; Drake, J. F.; Zieger, B.; Michael, A.; Toth, G.;
   Swisdak, M.; Gombosi, T. I.
2015AGUFMSH41A2371O    Altcode:
  Recently we proposed (Opher et al. 2015) that the structure of the
  heliosphere might be very different than we previously thought. The
  classic accepted view of the heliosphere is a quiescent, comet-like
  shape aligned in the direction of the Sun's travel through the
  interstellar medium (ISM) extending for thousands of astronomical
  units. We have shown, based on magnetohydrodynamic (MHD) simulations,
  that the tension force of the twisted magnetic field of the Sun
  confines the solar wind plasma beyond the termination shock and drives
  jets to the north and south very much like astrophysical jets. These
  heliospheric jets are deflected into the tail region by the motion of
  the Sun through the ISM. As in some astrophysical jets the interstellar
  wind blows the two jets into the tail but is not strong enough to force
  the lobes into a single comet-like tail. Instead, the interstellar wind
  flows around the heliosphere and into the equatorial region between
  the two jets. We show that the heliospheric jets are turbulent (due
  to large-scale MHD instabilities and reconnection) and strongly mix
  the solar wind with the ISM. The resulting turbulence has important
  implications for particle acceleration in the heliosphere. The two-lobe
  structure is consistent with the energetic neutral atom (ENA) images of
  the heliotail from IBEX where two lobes are visible in the north and
  south and the suggestion from the Cassini ENAs that the heliosphere
  is "tailless." The new structure of the heliosphere is supported by
  recent analytic work (Drake et al. 2015) that shows that even in high
  β heliosheath the magnetic field plays a crucial role in funneling the
  solar wind in two jets. Here we present these recent results and show
  that the heliospheric jets mediate the draping of the magnetic field
  and the conditions ahead of the heliopause. We show that reconnection
  between the interstellar and solar magnetic field both at the flanks of
  the jets and in between them twist the interstellar magnetic field in a
  small layer ahead of the HP in agreement with Voyager 1 observations (as
  seen in Opher &amp; Drake 2013). We present results of the heliospheric
  jets for a weaker magnetic field, representative of the 2010-2012
  period and what is expected to be seen in the ENA maps with solar cycle.

---------------------------------------------------------
Title: The Heliocentric Distance where the Deflections and Rotations
    of Solar Coronal Mass Ejections Occur
Authors: Kay, C.; Opher, M.
2015ApJ...811L..36K    Altcode: 2015arXiv150904948K
  Understanding the trajectory of a coronal mass ejection (CME), including
  any deflection from a radial path, and the orientation of its magnetic
  field is essential for space weather predictions. Kay et al. developed
  a model, Forecasting a CME’s Altered Trajectory (ForeCAT), of CME
  deflections and rotation due to magnetic forces, not including the
  effects of reconnection. ForeCAT is able to reproduce the deflection
  of observed CMEs. The deflecting CMEs tend to show a rapid increase
  of their angular momentum close to the Sun, followed by little to no
  increase at farther distances. Here we quantify the distance at which
  the CME deflection is “determined,” which we define as the distance
  after which the background solar wind has negligible influence on the
  total deflection. We consider a wide range in CME masses and radial
  speeds and determine that the deflection and rotation of these CMEs
  can be well-described by assuming they propagate with constant angular
  momentum beyond 10 R<SUB>⊙</SUB>. The assumption of constant angular
  momentum beyond 10 R<SUB>⊙</SUB> yields underestimates of the total
  deflection at 1 AU of only 1%-5% and underestimates of the rotation
  of 10%. Since the deflection from magnetic forces is determined by
  10 R<SUB>⊙</SUB>, non-magnetic forces must be responsible for any
  observed interplanetary deflections or rotations where the CME has
  increasing angular momentum.

---------------------------------------------------------
Title: Constraining the pickup ion abundance and temperature through
    the multifluid reconstruction of the Voyager 2 termination shock
    crossing
Authors: Zieger, Bertalan; Opher, Merav; Tóth, Gábor; Decker,
   Robert B.; Richardson, John D.
2015JGRA..120.7130Z    Altcode:
  Voyager 2 observations revealed that the hot solar wind ions (the
  so-called pickup ions) play a dominant role in the thermodynamics
  of the termination shock and the heliosheath. The number density and
  temperature of this hot population, however, have remained unknown,
  since the plasma instrument on board Voyager 2 can only detect the
  colder thermal ion component. Here we show that due to the multifluid
  nature of the plasma, the fast magnetosonic mode splits into a
  low-frequency fast mode and a high-frequency fast mode. The coupling
  between the two fast modes results in a quasi-stationary nonlinear
  wave mode, the "oscilliton," which creates a large-amplitude trailing
  wave train downstream of the thermal ion shock. By fitting multifluid
  shock wave solutions to the shock structure observed by Voyager 2,
  we are able to constrain both the abundance and the temperature of
  the undetected pickup ions. In our three-fluid model, we take into
  account the nonnegligible partial pressure of suprathermal energetic
  electrons (0.022-1.5 MeV) observed by the Low-Energy Charged Particle
  Experiment instrument on board Voyager 2. The best fitting simulation
  suggests a pickup ion abundance of 20 ± 3%, an upstream pickup ion
  temperature of 13.4 ± 2 MK, and a hot electron population with an
  apparent temperature of ~0.83 MK. We conclude that the actual shock
  transition is a subcritical dispersive shock wave with low Mach number
  and high plasma β.

---------------------------------------------------------
Title: Conditions for the existence of Kelvin-Helmholtz instability
    in a CME
Authors: Jatenco-Pereira, Vera; Páez, Andrés; Falceta-Gonçalves,
   Diego; Opher, Merav
2015IAUGA..2226591J    Altcode:
  The presence of Kelvin-Helmholtz instability (KHI) in the sheaths of
  the Coronal Mass Ejection (CME) has motivated several analysis and
  simulations to test their existence. In the present work we assume the
  existence of the KHI and propose a method to identify the regions where
  it is possible the development of KHI for a CME propagating in a fast
  and slow solar wind. We build functions for the velocities, densities
  and magnetic fields for two different zones of interaction between the
  solar wind and a CME. Based on the theory of magnetic KHI proposed by
  Chandrasekhar (1961) and we found conditions for the existence of KHI
  in the CME sheaths. Using this method it is possible to determine the
  range of parameters, in particular CME magnetic fields in which the
  KHI could exist. We conclude that KHI may exist in the two CME flanks
  and it is perceived that the zone with boundaries with the slow solar
  wind is more appropriated for the formation of the KHI.

---------------------------------------------------------
Title: A Model of the Heliosphere with Jets
Authors: Drake, J. F.; Swisdak, M.; Opher, M.
2015ApJ...808L..44D    Altcode: 2015arXiv150501451D
  An analytic model of the heliosheath (HS) between the termination shock
  (TS) and the heliopause (HP) is developed in the limit in which the
  interstellar flow and magnetic field are neglected. The heliosphere
  in this limit is axisymmetric and the overall structure of the HS
  and HP is controlled by the solar magnetic field even in the limit
  in which the ratio of the plasma to magnetic field pressure, β =
  8πP/B<SUP>2</SUP>, in the HS is large. The tension of the solar
  magnetic field produces a drop in the total pressure between the
  TS and the HP. This same pressure drop accelerates the plasma flow
  downstream of the TS into the north and south directions to form
  two collimated jets. The radii of these jets are controlled by the
  flow through the TS and the acceleration of this flow by the magnetic
  field—a stronger solar magnetic field boosts the velocity of the jets
  and reduces the radii of the jets and the HP. MHD simulations of the
  global heliosphere embedded in a stationary interstellar medium match
  well with the analytic model. The results suggest that mechanisms that
  reduce the HS plasma pressure downstream of the TS can enhance the jet
  outflow velocity and reduce the HP radius to values more consistent
  with the Voyager 1 observations than in current global models.

---------------------------------------------------------
Title: Solar Cycle Variation of the Magnetic Field Strength and
    Magnetic Dissipation Effects in the Heliosheath
Authors: Michael, Adam Thomas; Opher, Merav; Provornikova, Elena;
   Richardson, John; Toth, Gabor
2015shin.confE..81M    Altcode:
  We investigate the role the 11-year solar cycle variation of the
  magnetic field strength as well as magnetic dissipation effects have on
  the flows within the heliosheath using a global 3D magnetohydrodynamic
  model of the heliosphere. We use time and latitude-dependent solar
  wind velocity and density inferred from SOHO/SWAN and IPS data and
  implemented solar cycle variations of the magnetic field derived from
  27-day averages of the field magnitude average of the magnetic field at
  1 AU from the OMNI database. This model predicts Voyager 1 (V1) and 2
  (V2) will observe similar plasma parameters within the HS. While this
  model accurately predicts the observations at V2, it does not reproduce
  the decrease in radial velocity or drop in magnetic flux observed by
  V1. This implies that the solar cycle variations in solar wind magnetic
  field observed at 1 AU do not cause the order of magnitude decrease
  in magnetic flux observed in the V1 data. We describe the solar wind
  magnetic field as a monopole, to remove the heliospheric current sheet
  (HCS), with the magnetic field aligned with that of the interstellar
  medium. This diminishes any numerical reconnection at the ISM - solar
  wind interface as well as within the heliosheath itself. We compare
  our model to the same model describing the solar wind magnetic field
  as a dipole. In the dipole case, there is an intrinsic loss of magnetic
  energy near the HCS due to reconnection. This reconnection is numerical
  since we do not include real resistivity in the model. The comparison of
  the two models allows for an estimation of the effects of reconnection
  in the HS. We compare both models to observations along V1 and V2 and
  discuss whether magnetic dissipation is a significant process affecting
  the flows within the heliosheath.

---------------------------------------------------------
Title: The Effect of the Heating and Acceleration of Winds on
Conditions Ahead of Hot Jupiters: Solar and V374 Peg Cases
Authors: Kornbleuth, Marc Zachary; Opher, Merav; Evans, Rebekah M.
2015shin.confE..88K    Altcode:
  We study how different heating and acceleration processes of stellar
  winds affect their mass-loss rates and the conditions near exo-planets
  at close distances of 10 stellar radii. The exact mechanisms responsible
  for the heating and acceleration of the solar wind are still being
  debated. We explore thermal heating (Cohen et al. 2007) (TER) and
  an Alfvén wave driven wind with Alfvén wave damping by turbulence
  and surface Alfvén waves (Evans et al. 2012) (ALF). For different
  solar wind models, we find a difference of orders of magnitude in
  mass-loss rates for the same lower corona density and temperature. For
  the M dwarf star V374 Peg, the two heating processes yield mass-loss
  rates differing by a factor of 80%. For this star, an isothermal model
  (Vidotto et al. 2011) (ISO) yields a different mass-loss rate from TER
  by a factor of 80% and from ALF by a factor of 230%. The difference
  between the mass-loss rates stems from constant, extended heating of
  ISO, whereas TER and ALF have a strong variance in heating until two
  stellar radii. When comparing the heating rates of ALF and TER, the
  rates differ by an order of magnitude. These large differences indicate
  the importance of the heating and acceleration of winds. These different
  heating mechanisms also predict different conditions ahead of Hot
  Jupiters for distances near 10 stellar radii. Perpendicular diffusion
  has been particularly challenging for physicists. One of the relatively
  unexplored topic has been the effect of turbulent structures in a
  realistic physical scenario. Previous works have utilized the synthetic
  realization of data that have Gaussian Probability Density Functions
  (PDFs) of magnetic field differences and currents. The fields generated
  this way does not take into account the effects of intermittency and
  coherent structures on the diffusion coefficient. In this study we
  use the results of fields generated from reduced magnetohydrodynamic
  (RMHD) turbulence with and without phase randomization to examine the
  effects of spatial structures and intermittency on the perpendicular
  diffusion of charged particles.

---------------------------------------------------------
Title: Radial Evolution of CME Deflection and Angular Momentum
Authors: Kay, Christina Danielle; Opher, Merav
2015shin.confE.167K    Altcode:
  Understanding the trajectory of a coronal mass ejection (CME), including
  any deflection from a radial path, is essential for space weather
  predictions. Kay et al. (2015a) developed a model, Forecasting a CME's
  Altered Trajectory (ForeCAT), of CME deflection due to magnetic forces
  that reproduces the general trends in the magnitude and direction of
  observed CME deflections. ForeCAT can also reproduce the deflection
  of individual observed CMEs (Kay et al. 2015b). The deflecting CMEs
  tend to show a rapid increase in the angular momentum close to the
  Sun, followed by little to no increase at farther distances. Here we
  quantify the distance at which the CME deflection is 'determined,'
  which we define as the distance after which the background solar
  wind has negligible influence on the total deflection. We determine
  this distance by calculating the radial distance at which the CME
  reaches either 90% of its total deflection or angular momentum at 1
  AU. We consider a wide range in CME mass and velocity parameter space
  and find that the deflection is typically determined by 2 Rs. This
  implies that non-magnetic forces must be responsible for any observed
  interplanetary deflections where the CME actually accelerates and that
  it is absolutely essential to accurately describe the solar environment
  below 2 Rs to obtain accurate predictions of CME deflections.

---------------------------------------------------------
Title: Global Trends of CME Deflections Based on CME and Solar
    Parameters
Authors: Kay, C.; Opher, M.; Evans, R. M.
2015ApJ...805..168K    Altcode: 2014arXiv1410.4496K
  Accurate space weather forecasting requires knowledge of the trajectory
  of coronal mass ejections (CMEs), including any deflections close
  to the Sun or through interplanetary space. Kay et al. introduced
  ForeCAT, a model of CME deflection resulting from the background
  solar magnetic field. For a magnetic field solution corresponding to
  Carrington Rotation (CR) 2029 (declining phase, 2005 April-May), the
  majority of the CMEs deflected to the Heliospheric Current Sheet, the
  minimum in magnetic pressure on global scales. Most of the deflection
  occurred below 4 {{R}<SUB>⊙ </SUB>}. Here we extend ForeCAT to
  include a three-dimensional description of the deflecting CME. We
  attempt to answer the following questions: (1) do all CMEs deflect
  to the magnetic minimum? and (2) does most deflection occur within
  the first few solar radii (4 {{R}<SUB>⊙ </SUB>})? Results for solar
  minimum and declining-phase CMEs show that not every CME deflects to
  the magnetic minimum and that typically the majority of the deflection
  occurs below 10 {{R}<SUB>⊙ </SUB>}. Slow, wide, low-mass CMEs in
  declining-phase solar backgrounds with strong magnetic field and
  magnetic gradients exhibit the largest deflections. Local gradients
  related to active regions tend to cause the largest deviations from the
  deflection predicted by global magnetic gradients, but variations can
  also be seen for CMEs in the quiet-Sun regions of the declining-phase
  CR. We show the torques due to differential forces along the CME can
  cause rotation about the CME’s toroidal axis.

---------------------------------------------------------
Title: Magnetic Flux Conservation in the Heliosheath Including Solar
    Cycle Variations of Magnetic Field Intensity
Authors: Michael, A. T.; Opher, M.; Provornikova, E.; Richardson,
   J. D.; Tóth, G.
2015ApJ...803L...6M    Altcode:
  In the heliosheath (HS), Voyager 2 has observed a flow with constant
  radial velocity and magnetic flux conservation. Voyager 1, however,
  has observed a decrease in the flow’s radial velocity and an order of
  magnitude decrease in magnetic flux. We investigate the role of the 11
  yr solar cycle variation of the magnetic field strength on the magnetic
  flux within the HS using a global 3D magnetohydrodynamic model of the
  heliosphere. We use time and latitude-dependent solar wind velocity
  and density inferred from Solar and Heliospheric Observatory/SWAN
  and interplanetary scintillations data and implemented solar cycle
  variations of the magnetic field derived from 27 day averages of
  the field magnitude average of the magnetic field at 1 AU from the
  OMNI database. With the inclusion of the solar cycle time-dependent
  magnetic field intensity, the model matches the observed intensity
  of the magnetic field in the HS along both Voyager 1 and 2. This is
  a significant improvement from the same model without magnetic field
  solar cycle variations, which was over a factor of two larger. The
  model accurately predicts the radial velocity observed by Voyager 2;
  however, the model predicts a flow speed ∼100 km s<SUP>-1</SUP>
  larger than that derived from LECP measurements at Voyager 1. In the
  model, magnetic flux is conserved along both Voyager trajectories,
  contrary to observations. This implies that the solar cycle variations
  in solar wind magnetic field observed at 1 AU does not cause the order
  of magnitude decrease in magnetic flux observed in the Voyager 1 data.

---------------------------------------------------------
Title: Constraining the Masses and the Non-radial Drag Coefficient
    of a Solar Coronal Mass Ejection
Authors: Kay, C.; dos Santos, L. F. G.; Opher, M.
2015ApJ...801L..21K    Altcode: 2015arXiv150300664K
  Decades of observations show that coronal mass ejections (CMEs)
  can deflect from a purely radial trajectory, however, no consensus
  exists as to the cause of these deflections. Many theories attribute
  CME deflection to magnetic forces. We developed Forecasting a CMEs
  Altered Trajectory (ForeCAT), a model for CME deflections based
  solely on magnetic forces, neglecting any reconnection effects. Here,
  we compare ForeCAT predictions to the observed deflection of the
  2008 December 12 CME and find that ForeCAT can accurately reproduce
  the observations. Multiple observations show that this CME deflected
  nearly 30° in latitude and 4.°4 in longitude. From the observations,
  we are able to constrain all of the ForeCAT input parameters (initial
  position, radial propagation speed, and expansion) except the CME mass
  and the drag coefficient that affects the CME motion. By minimizing the
  reduced chi-squared, χ <SUB>ν </SUB><SUP>2</SUP>, between the ForeCAT
  results and the observations, we determine an acceptable mass range
  between 4.5 × 10<SUP>14</SUP> and 1 × 10<SUP>15</SUP> g and a drag
  coefficient less than 1.4 with a best fit at 7.5 × 10<SUP>14</SUP>
  g and 0 for the mass and drag coefficient. ForeCAT is sensitive to
  the magnetic background and we are also able to constrain the rate
  at which the quiet Sun magnetic field falls to be similar or slightly
  slower than the Potential Field Source Surface model.

---------------------------------------------------------
Title: Magnetized Jets Driven By the Sun: the Structure of the
    Heliosphere Revisited
Authors: Opher, M.; Drake, J. F.; Zieger, B.; Gombosi, T. I.
2015ApJ...800L..28O    Altcode: 2014arXiv1412.7687O
  The classic accepted view of the heliosphere is a quiescent, comet-like
  shape aligned in the direction of the Sun’s travel through the
  interstellar medium (ISM) extending for thousands of astronomical units
  (AUs). Here, we show, based on magnetohydrodynamic (MHD) simulations,
  that the tension (hoop) force of the twisted magnetic field of the Sun
  confines the solar wind plasma beyond the termination shock and drives
  jets to the north and south very much like astrophysical jets. These
  jets are deflected into the tail region by the motion of the Sun through
  the ISM similar to bent galactic jets moving through the intergalactic
  medium. The interstellar wind blows the two jets into the tail but is
  not strong enough to force the lobes into a single comet-like tail,
  as happens to some astrophysical jets. Instead, the interstellar wind
  flows around the heliosphere and into the equatorial region between the
  two jets. As in some astrophysical jets that are kink unstable, we show
  here that the heliospheric jets are turbulent (due to large-scale MHD
  instabilities and reconnection) and strongly mix the solar wind with the
  ISM beyond 400 AU. The resulting turbulence has important implications
  for particle acceleration in the heliosphere. The two-lobe structure is
  consistent with the energetic neutral atom (ENA) images of the heliotail
  from IBEX where two lobes are visible in the north and south and the
  suggestion from the Cassini ENAs that the heliosphere is “tailless.”

---------------------------------------------------------
Title: Interstellar Mapping and Acceleration Probe (IMAP) - Its Time
    Has Come!
Authors: Schwadron, N.; Kasper, J. C.; Mewaldt, R. A.; Moebius, E.;
   Opher, M.; Spence, H. E.; Zurbuchen, T.
2014AGUFMSH21D..01S    Altcode:
  Our piece of cosmic real-estate, the heliosphere, is the domain
  of all human existence -- an astrophysical case-history of the
  successful evolution of life in a habitable system. By exploring
  our global heliosphere and its myriad interactions, we develop key
  physical knowledge of the interstellar interactions that influence
  exoplanetary habitability as well as the distant history and destiny
  of our solar system and world. IBEX was the first mission to explore
  the global heliosphere and in concert with Voyager 1 and Voyager 2
  is discovering a fundamentally new and uncharted physical domain of
  the outer heliosphere. The enigmatic IBEX ribbon is an unanticipated
  discovery demonstrating that much of what we know or think we understand
  about the outer heliosphere needs to be revised. The next quantum leap
  enabled by IMAP will open new windows on the frontier of Heliophysics
  at a time when the space environment is rapidly evolving. IMAP with 100
  times the combined resolution and sensitivity of IBEX will discover
  the substructure of the IBEX ribbon and will reveal in unprecedented
  resolution global maps of our heliosphere. The remarkable synergy
  between IMAP, Voyager 1 and Voyager 2 will remain for at least the
  next decade as Voyager 1 pushes further into the interstellar domain
  and Voyager 2 moves through the heliosheath. Voyager 2 moves outward
  in the vicinity of the IBEX ribbon and its plasma measurements will
  create singular opportunities for discovery in the context of IMAP's
  global measurements. IMAP, like ACE before it, will be a keystone of
  the Heliophysics System Observatory by providing comprehensive cosmic
  ray, energetic particle, pickup ion, suprathermal ion, neutral atom,
  solar wind, solar wind heavy ion, and magnetic field observations to
  diagnose the changing space environment and understand the fundamental
  origins of particle acceleration. Thus, IMAP is a mission whose time
  has come. IMAP is the highest ranked next Solar Terrestrial Probe in
  the Decadal Survey, is ready to be implemented and explores fundamental
  outstanding problems in Heliophysics concerning the outer boundaries
  of our solar system, the physics of interstellar interactions with
  the solar wind, the origin and physics of the IBEX ribbon, and the
  fundamental origins particle acceleration throughout the heliosphere.

---------------------------------------------------------
Title: The Interaction of Solar Eruptions and Large-Scale Coronal
    Structures Revealed Through Modeling and Observational Analysis
Authors: Evans, R. M.; Savcheva, A. S.; Zink, J. L.; Muglach, K.;
   Kozarev, K. A.; Opher, M.; van der Holst, B.
2014AGUFMSH11D..05E    Altcode:
  We use numerical and observational approaches to explore how
  the interaction of a coronal mass ejection (CME) with preexisting
  structures in the solar atmosphere influences its evolution and space
  weather effects. We study two aspects of CME evolution: deflection of
  the CME's propagation direction, and expansion. First, we perform a
  statistical study of the influence of coronal holes on CME trajectories
  for more than 50 events during years 2010-2014. Second, we use the Space
  Weather Modeling Framework (SWMF) to model CME propagation in the Alfven
  Wave Solar Model (AWSoM), which includes a sophisticated treatment
  of the physics of coronal heating and solar wind acceleration. The
  major progress in these simulations is that the initial conditions
  of the eruptions are highly data-constrained. From the simulations,
  we determine the CME's trajectory and expansion. We calculate the
  pile-up of material along the front and sides of a CME due to its
  expansion, and constrain the properties of the pile-up under a range
  of conditions. Finally, we will discuss the connection between these
  plasma density structures and the acceleration of protons to energies
  relevant to space weather.

---------------------------------------------------------
Title: Magnetic Reconnection in the Heliospheric Current Sheet:
    The Implications of the Different Environments Seen by the
    VoyagerSpacecraft
Authors: Swisdak, M. M.; Drake, J. F.; Opher, M.
2014AGUFMSH11B4048S    Altcode:
  The magnetic field abutting the heliospheric current sheet (HCS)
  is primarily in the azimuthal direction, either east-to-west or
  west-to-east. Mis-alignment of the solar rotational and magnetic
  axesleads to the characteristic ballerina-skirt shape of the HCS
  and during the solar cycle there can be large excursions in the
  sheet's latitudinal extent. Voyager 2's observations of energetic
  electrondropouts are related to its crossing of this boundary. Magnetic
  reconnection is also thought to occur as the HCS compresses and narrows
  between the termination shock and the heliopause. Near theequator the
  two HCS field alignments are present in roughly equal amounts, while
  near the edges the distribution can be considerably skewed. This will
  lead to substantial differences in the environmentsof the two Voyager
  spacecraft since Voyager 1 is north of the equator, but firmly in the
  sector region, while Voyager 2 is south of the equator and skirting
  the edges of the sector region. We presentparticle-in-cell simulations
  demonstrating the consequences of the reconnection of asymmetric amounts
  of flux. In particular, we will discuss Voyager 2's remaining time
  in the heliosphere -- including theimplications for the solar wind
  velocity, energetic particle transport, and the expected structure
  of Voyager 2's heliopause crossing -- and compare it with the data
  collected from Voyager 1.

---------------------------------------------------------
Title: The Multi-fluid Nature of the Termination Shock
Authors: Zieger, B.; Opher, M.; Toth, G.
2014AGUFMSH21D..05Z    Altcode:
  After the crossing of the termination shock by the Voyager spacecraft,
  it became clear that pickup ions (PUIs) dominate the thermodynamics
  of the heliosheath. Particle-in-cell simulations by Wu et al. [2010]
  have shown that the sum of the thermal solar wind and non-thermal PUI
  distributions downstream of the termination shock can be approximated
  with a 2-Maxwellian distribution. Therefore the heliosheath can be
  described as multi-fluid plasma comprising of cold thermal solar
  wind ions, hot pickup ions (PUI) and electrons. The abundance of
  the hot pickup ion population has remained unknown, since the plasma
  instrument on board Voyager 2 can only detect the colder thermal ion
  component. Upstream of the termination shock, where the solar wind bulk
  flow is quasi-perpendicular to the Parker spiral-like heliospheric
  magnetic field, the two ion fluids are fully coupled. However, in
  the heliosheath, where the ion flows start to divert from the radial
  direction, PUIs and thermal solar wind ions become decoupled in the
  parallel direction, resulting in differential ion flow velocities. This
  multi-fluid nature of the heliosheath cannot be captured in current
  single-fluid MHD models of the heliosphere. Here we present our new
  multi-ion Hall MHD model of the termination shock, which is able to
  resolve finite gyroradius effects [Zieger et al., 2014]. The addition
  of hot PUIs to the mixture of thermal solar wind protons and cold
  electrons results in the mode splitting of fast magnetosonic waves
  into a high-frequency fast mode (or PUI mode) and a low-frequency fast
  mode (or thermal proton mode). We show that the multi-fluid nature of
  the solar wind predicts two termination shocks, one in the thermal
  and the other in the pickup ion component. We demonstrate that the
  thermal ion shock is a dispersive shock wave, with a trailing wave
  train, which is a quasi-stationary nonlinear wave mode, also known
  as oscilliton. We constrain the previously unknown PUI abundance and
  the PUI temperature by fitting simulated multi-fluid termination shock
  profiles to Voyager 2 observations. Our model provides self-consistent
  energy partitioning between the ion species across the termination shock
  and predicts the preferential heating of the thermal ion component. The
  nonlinear oscilliton mode can be a source of compressional turbulence
  in the heliosheath.

---------------------------------------------------------
Title: Global Field Orientation Across the Heliopause As a Result
    of Regions of Reconnection
Authors: Opher, M.; Drake, J. F.; Zieger, B.; Gombosi, T. I.
2014AGUFMSH11B4043O    Altcode:
  Based on the difference between the orientation of the interstellar and
  the solar magnetic fields, there was an expectation by the community
  that the magnetic field direction will rotate dramatically across the
  heliopause (HP). Based on the radio emission, the Voyager team concluded
  that Voyager 1 (V1) crossed into interstellar space at the end of August
  2013. The question is then why there was no significant rotation in
  the direction of the magnetic field across the HP. Our recent global
  simulations (Opher &amp; Drake 2013) revealed that strong rotations
  in the direction of the magnetic field at the HP at the location of
  V1 (and Voyager 2) are not expected. We showed that for a wide range
  of orientations of BISM the angle δ = a sin(BN /B) is small (around
  10◦-20◦) ahead of V1 as seen in the observations. Only after some
  significant distance outside the HP (~ 20AU) is the direction of the
  interstellar field distinguishably different from that of the Parker
  spiral. The field outside the HP slowly rotates with a small change
  (around 2 degree/AU); as seen by observations (Burlaga &amp; Ness
  2014). Here we show that the reason for the twist of the BISM to the
  solar direction is due to favorable locations for global reconnection
  on the HP. We explore of the effect of the location of the reconnection
  on the draping of the magnetic field and flows just outside the HP. We
  further explore the consequences for what Voyager 2 will encounter.

---------------------------------------------------------
Title: Magnetic Dissipation Effects on the Flows within the
    Heliosheath
Authors: Michael, A.; Opher, M.; Provornikova, E.; Toth, G.
2014AGUFMSH11B4041M    Altcode:
  We investigate the effect that magnetic dissipation has on the
  flows within the heliosheath (HS), the subsonic plasma in between
  the termination shock (TS) and the heliopause (HP). We use a global
  3D multi-fluid magnetohydrodynamic (MHD) model of the heliosphere,
  which has a grid resolution of 0.5 AU within the heliosphere along
  both Voyager 1 and Voyager 2 trajectories. We describe the solar
  wind magnetic field as a monopole, to remove the heliospheric current
  sheet, with the magnetic field aligned with that of the interstellar
  medium (ISM) to diminish any numerical reconnection at the ISM -
  solar wind interface. This configuration of the solar wind magnetic
  field also reduces any numerical magnetic dissipation effects in the
  HS. We compare our model to the same model describing the solar wind
  magnetic field as a dipole. In the dipole case, there is an intrinsic
  loss of magnetic energy near the heliospheric current sheet (HCS)
  due to reconnection. This reconnection is numerical since we do not
  include real resistivity in the model. The comparison of the two models
  will allow for an estimation of the effects of reconnection in the HS
  since there is no numerical dissipation of the magnetic field in the
  monopole model. We compare steady state solutions and the role magnetic
  dissipation has on the global characteristics of the heliosphere. We
  find that the monopole model of the solar wind magnetic field removes
  the asymmetry observed in the TS and predicted for the HP. Furthermore,
  the TS is considerably closer to the Sun in the monopole model due
  to the build up of magnetic filed at the HP. We also investigate
  magnetic dissipation effects in the 11-year solar cycle variations
  of the solar wind in a 3D time-dependent model. This model includes
  3D latitudinal and temporal variations of the solar wind density
  and velocity taken from SOHO/SWAN and IPS data from 1990 to 2012 as
  described in Provornikova et al. 2014. We additionally include a time
  varying magnetic field obtained from the OMNI database. We compare
  both models to observations along Voyager 1 and Voyager 2 and discuss
  whether magnetic dissipation is a significant process affecting the
  flows within the HS.

---------------------------------------------------------
Title: Magnetic Reconnection in Interplanetary Coronal Mass Ejections
Authors: Fermo, R. L.; Opher, M.; Drake, J. F.
2014AGUFMSH22A..02F    Altcode:
  Magnetic reconnection is a ubiquitous phenomenon in many varied space
  and astrophysical plasmas, and as such plays an important role in
  the dynamics of interplanetary coronal mass ejections (ICMEs). It is
  widely regarded that reconnection is instrumental in the formation and
  ejection of the initial CME flux rope, but reconnection also continues
  to affect the dynamics as it propagates through the interplanetary
  medium. For example, reconnection on the leading edge of the ICME,
  by which it interacts with the interplanetary medium, leads to
  flux erosion. However, recent in situ observations by Gosling et
  al. found signatures of reconnection exhausts in the interior. In
  light of this data, we consider the stability properties of systems
  with this flux rope geometry with regard to their minimum energy
  Taylor state. Variations from this state will result in the magnetic
  field relaxing back towards the minimum energy state, subject to
  the constraints that the toroidal flux and magnetic helicity remain
  invariant. In reversed field pinches, this relaxation is mediated
  by reconnection in the interior of the system, as has been shown
  theoretically and experimentally. By treating the ICME flux rope in
  a similar fashion, we show analytically that the the elongation of
  the flux tube cross section in the latitudinal direction will result
  in a departure from the Taylor state. The resulting relaxation of the
  magnetic field causes reconnection to commence in the interior of the
  ICME, in agreement with the observations of Gosling et al. We present
  MHD simulations in which reconnection initiates at a number of rational
  surfaces, and ultimately produces a stochastic magnetic field. If the
  time scales for this process are shorter than the propagation time to
  1 AU, this result explains why many ICME flux ropes no longer exhibit
  the smooth, helical flux structure characteristic of a magnetic cloud.

---------------------------------------------------------
Title: ForeCAT: Using CME Deflections to Constrain their Mass and
    the Drag
Authors: Kay, C.; dos Santos, L. F. G.; Opher, M.
2014AGUFMSH43B4210K    Altcode:
  Observations show that CMEs can deflect from a purely radial trajectory
  yet no consensus exists as to the cause of these deflections. The
  majority of the deflection motion occurs in the corona at distances
  where the magnetic energy dominates. Accordingly, many theories
  attribute the CME deflection to magnetic forces. In Kay et al. (2013)
  we presented ForeCAT, a model for CME deflections based on the magnetic
  forces (magnetic tension and magnetic pressure gradients). Kay
  et al. (2014) introduced an improved three-dimensional version of
  ForeCAT. Here we study the 2008 December 12 CME which occurred during
  solar minimum of Solar Cycle 24 (Byrne et al 2010, Gui et al. 2011,
  Liu et al 2010a,b). This CME erupted from high latitudes, and,
  despite the weak background magnetic field, deflected to the ecliptic,
  impacting Earth. From the observations, we are able to constrain all
  of the ForeCAT input parameters except for the CME mass and the drag
  coefficient that affects the CME motion. The reduced chi-square best
  fit to the observations constrains the CME mass range to 3e14 to 7e14
  g and the drag coefficient range to 1.9 to 2.4. We explore the effects
  of a different magnetic background which decreases less rapidly than
  our standard Potential Field Source Surface (PFSS) model, as type II
  radio bursts suggest that the PFSS magnetic field decays too rapidly
  above active regions. For the case of the filament eruption of 2008
  December 12 we find that the quiet sun coronal magnetic field should
  behave similar to the PFSS model. Finally, we present our current work
  exploring the case of the 2008 April 9 CME.

---------------------------------------------------------
Title: Plasma Flows in the Heliosheath along the Voyager 1 and 2
    Trajectories due to Effects of the 11 yr Solar Cycle
Authors: Provornikova, E.; Opher, M.; Izmodenov, V. V.; Richardson,
   J. D.; Toth, G.
2014ApJ...794...29P    Altcode:
  We investigate the role of the 11 yr solar cycle variations in the
  solar wind (SW) parameters on the flows in the heliosheath using a new
  three-dimensional time-dependent model of the interaction between the
  SW and the interstellar medium. For boundary conditions in the model we
  use realistic time and the latitudinal dependence of the SW parameters
  obtained from SOHO/SWAN and interplanetary scintillation data for the
  last two solar cycles (1990-2011). This data set generally agrees with
  the in situ Ulysses measurements from 1991 to 2009. For the first ~30
  AU of the heliosheath the time-dependent model predicts constant radial
  flow speeds at Voyager 2 (V2), which is consistent with observations
  and different from the steady models that show a radial speed decrease
  of 30%. The model shows that V2 was immersed in SW with speeds of
  500-550 km s<SUP>-1</SUP> upstream of the termination shock before
  2009 and in wind with upstream speeds of 450-500 km s<SUP>-1</SUP>
  after 2009. The model also predicts that the radial velocity along
  the Voyager 1 (V1) trajectory is constant across the heliosheath,
  contrary to observations. This difference in observations implies that
  additional effects may be responsible for the different flows at V1
  and V2. The model predicts meridional flows (VN) higher than those
  observed because of the strong bluntness of the heliosphere shape in
  the N direction in the model. The modeled tangential velocity component
  (VT) at V2 is smaller than observed. Both VN and VT essentially depend
  on the shape of the heliopause.

---------------------------------------------------------
Title: Magnetic Reconnection in the Interior of Interplanetary
    Coronal Mass Ejections
Authors: Fermo, R. L.; Opher, M.; Drake, J. F.
2014PhRvL.113c1101F    Altcode:
  Recent in situ observations of interplanetary coronal mass ejections
  (ICMEs) found signatures of reconnection exhausts in their interior or
  trailing edge. Whereas reconnection on the leading edge of an ICME would
  indicate an interaction with the coronal or interplanetary environment,
  this result suggests that the internal magnetic field reconnects with
  itself. In light of this data, we consider the stability properties of
  flux ropes first developed in the context of astrophysics, then further
  elaborated upon in the context of reversed field pinches (RFPs). It
  was shown that the lowest energy state of a flux rope corresponds to
  ∇×B=λB with λ a constant, the so-called Taylor state. Variations
  from this state will result in the magnetic field trying to reorient
  itself into the Taylor state solution, subject to the constraints that
  the toroidal flux and magnetic helicity are invariant. In reversed
  field pinches, this relaxation is mediated by the reconnection of
  the magnetic field, resulting in a sawtooth crash. If we likewise
  treat the ICME as a flux rope, any deviation from the Taylor state
  will result in reconnection within the interior of the flux tube, in
  agreement with the observations by Gosling et al. Such a departure
  from the Taylor state takes place as the flux tube cross section
  expands in the latitudinal direction, as seen in magnetohydrodynamic
  (MHD) simulations of flux tubes propagating through the interplanetary
  medium. We show analytically that this elongation results in a state
  which is no longer in the minimum energy Taylor state. We then present
  magnetohydrodynamic simulations of an elongated flux tube which has
  evolved away from the Taylor state and show that reconnection at many
  surfaces produces a complex stochastic magnetic field as the system
  evolves back to a minimum energy state configuration.

---------------------------------------------------------
Title: Do All CMEs Deflect to the Magnetic Minimum by 4 Rs?
Authors: Kay, Christina Danielle; Opher, Merav
2014shin.confE..11K    Altcode:
  Accurate space weather forecasting requires knowledge of the trajectory
  of coronal mass ejections (CMEs), including any CME deflection close to
  the Sun or through interplanetary space. Kay et al. (2013) introduced
  ForeCAT, a model of CME deflection resulting from the background solar
  magnetic field. For a magnetic background corresponding to Carrington
  Rotation (CR) 2029, the majority of CMEs deflected to the streamer
  belt, the minimum in magnetic pressure, below 4 Rs. We have eliminated
  many of the underlying simplifications of ForeCAT presented in Kay et
  al. (2013) with a more detailed three dimensional description of the
  deflecting flux rope. We answer two questions: Do all CMEs deflect to
  the magnetic minimum? Does all deflection occur within 4 Rs?

---------------------------------------------------------
Title: Flux rope degradation of ICMEs by interior reconnection
Authors: Fermo, Raymond Luis; Opher, M.; Drake, J. F.
2014shin.confE..35F    Altcode:
  The magnetic structure of interplanetary coronal mass ejections
  (ICMEs) is often considered to be a magnetic cloud, characterized by a
  smooth rotation of the magnetic field. However, perhaps as few as 30%
  of observed ICMEs display such a coherent helical flux rope geometry
  (Gosling et al., 1990). We propose that reconnection in the interior
  of the ICME could result in a complex stochastic magnetic field and
  the destruction of the magnetic cloud structure. Such reconnection
  events within the core of ICMEs have been seen in recent in situ
  observations (Gosling et al., 2007). We show that reconnection can be
  initiated as the ICME flux rope becomes elongated in the latitudinal
  direction as it propagates through the interplanetary medium. This
  elongation forces the ICME flux rope from its force-free Taylor state,
  and as a consequence, the flux rope will attempt to relax back to that
  minimum energy state. Subject to the constraints that the toroidal
  flux and magnetic helicity are invariant, this relaxation must be
  mediated by reconnection of the interior magnetic field. We present
  MHD simulations of an elongated flux rope which has evolved away from
  the Taylor state and show that reconnection at many surfaces produces
  a stochastic magnetic field as the system evolves back to a minimum
  energy state configuration.

---------------------------------------------------------
Title: Implications of CME Deflections on the Habitability of Planets
    Around M Dwarfs
Authors: Kay, Christina; Opher, Merav
2014AAS...22412024K    Altcode:
  Solar coronal mass ejections (CMEs) are known to produce adverse
  space weather effects at Earth. These effects include geomagnetically
  induced currents and energetic particles accelerated by CME-driven
  shocks. Significant non-radial motions are observed for solar CMEs with
  the CME path deviating as much as 30 degrees within 20 solar radii. We
  have developed a model, Forecasting a CME's Altered Trajectory
  (ForeCAT), which predicts the deflected path of a CME according
  to the magnetic forces of the background solar wind. In Kay et al
  (2013), we show that these magnetic forces cause CMEs to deflect
  towards the region of minimum magnetic field strength. For the Sun,
  this magnetic minimum corresponds to the Heliospheric Current Sheet
  (HCS). We predict that the Earth is most likely to be impacted by a
  deflected CME when its orbit brings it near the HCS. M dwarfs can have
  magnetic field strengths several orders of magnitude larger than the
  Sun which will strongly affect CME deflections. We explore stellar CME
  deflections with ForeCAT. We present results for M4V star V374 Peg. We
  determine potential impacts caused by CME deflections for a planet
  located within the habitable zone of V374 Peg 20-40 solar radii). We
  discuss future extensions as including variations in solar cycle,
  capturing small structures such as active regions, and extensions for
  other M dwarf stars.

---------------------------------------------------------
Title: Do all CMEs deflect to the background magnetic minimum by 4Rs?
Authors: Kay, Christina; Opher, Merav
2014AAS...22430305K    Altcode:
  Accurate space weather forecasting requires knowledge of the trajectory
  of coronal mass ejections (CMEs), including any CME deflection close to
  the Sun or through interplanetary space. Kay et al. (2013) introduced
  ForeCAT, a model of CME deflection resulting from the background solar
  magnetic field. For a magnetic background corresponding to Carrington
  Rotation (CR) 2029 (declining phase, April-May 2005), the majority
  of the CMEs deflected to the streamer belt, the minimum in magnetic
  pressure. Most of the deflection occurred below 4 Rs. Here we explore
  the questions: a) Do all CMEs deflect to the magnetic minimum? and b)
  Does most deflection occur within 4 Rs? We have eliminated many of the
  underlying simplifications of ForeCAT presented in Kay et al. (2013)
  with a more detailed three dimensional description of the deflecting
  flux rope. The locations of coronal magnetic structures that determine
  the background magnetic minima vary throughout the solar cycle. We
  show that these variations reproduce observed trends in the direction
  of CME deflections throughout the solar cycle.

---------------------------------------------------------
Title: The behavior of the flows within the heliosheath
Authors: Michael, Adam; Opher, Merav; Provornikova, Elena; Toth, Gabor
2014shin.confE..61M    Altcode:
  The current Voyager measurements of the plasma flows reveal the complex
  nature of the heliosheath, the last boundary between the Solar System
  and the interstellar medium. These measurements are challenging
  the standard theories and models. We use a global 3D multi-fluid
  magnetohydrodynamic (MHD) model of the heliosphere to study the flows
  within the heliosheath. Our model has a grid resolution of 0.5 AU within
  the heliosphere, along both Voyager 1 and Voyager 2 trajectories,
  and describes the solar wind magnetic field as a monopole to avoid
  any numerical magnetic dissipation effects in the heliosheath. We find
  that the model predicts the heliosheath to be split into two regions,
  first a thermally dominated region downstream of the termination
  shock followed by a magnetically dominated region (? &lt; 1) just
  before the heliopause. We compare the solution to the same model
  with dipole description of the solar wind magnetic field. The dipole
  solar wind magnetic field includes a flat heliospheric current sheet
  where reconnection occurs due to numerical dissipation. The two models
  predict a considerably different heliosheath. We compare both models
  to observations along V1 and V2 and discuss whether we can use these
  models to predict when Voyager 2 is approaching the heliopause.

---------------------------------------------------------
Title: M-dwarf stellar winds: the effects of realistic magnetic
    geometry on rotational evolution and planets
Authors: Vidotto, A. A.; Jardine, M.; Morin, J.; Donati, J. F.; Opher,
   M.; Gombosi, T. I.
2014MNRAS.438.1162V    Altcode: 2013MNRAS.tmp.2947V; 2013arXiv1311.5063V
  We perform three-dimensional numerical simulations of stellar winds
  of early-M-dwarf stars. Our simulations incorporate observationally
  reconstructed large-scale surface magnetic maps, suggesting that the
  complexity of the magnetic field can play an important role in the
  angular momentum evolution of the star, possibly explaining the large
  distribution of periods in field dM stars, as reported in recent
  works. In spite of the diversity of the magnetic field topologies
  among the stars in our sample, we find that stellar wind flowing
  near the (rotational) equatorial plane carries most of the stellar
  angular momentum, but there is no preferred colatitude contributing
  to mass-loss, as the mass flux is maximum at different colatitudes
  for different stars. We find that more non-axisymmetric magnetic
  fields result in more asymmetric mass fluxes and wind total pressures
  p<SUB>tot</SUB> (defined as the sum of thermal, magnetic and ram
  pressures). Because planetary magnetospheric sizes are set by pressure
  equilibrium between the planet's magnetic field and p<SUB>tot</SUB>,
  variations of up to a factor of 3 in p<SUB>tot</SUB> (as found in the
  case of a planet orbiting at several stellar radii away from the star)
  lead to variations in magnetospheric radii of about 20 per cent along
  the planetary orbital path. In analogy to the flux of cosmic rays that
  impact the Earth, which is inversely modulated with the non-axisymmetric
  component of the total open solar magnetic flux, we conclude that
  planets orbiting M-dwarf stars like DT Vir, DS Leo and GJ 182, which
  have significant non-axisymmetric field components, should be the more
  efficiently shielded from galactic cosmic rays, even if the planets
  lack a protective thick atmosphere/large magnetosphere of their own.

---------------------------------------------------------
Title: Dependence of Energetic Ion and Electron Intensities on
Proximity to the Magnetically Sectored Heliosheath: Voyager 1 and
    2 Observations
Authors: Hill, M. E.; Decker, R. B.; Brown, L. E.; Drake, J. F.;
   Hamilton, D. C.; Krimigis, S. M.; Opher, M.
2014ApJ...781...94H    Altcode:
  Taken together, the Voyager 1 and 2 (V1 and V2) spacecraft have
  collected over 11 yr of data in the heliosheath. Despite extensive
  study, energetic particles and magnetic fields measured in the
  heliosheath have not been reconciled by existing models. In particular,
  the differences between the energetic particle intensity variations at
  V1 and V2 are unexplained. While energetic particle intensities at V1
  change gradually over 7 yr in the heliosheath, those at V2 vary by a
  factor ~10 in 1 yr. Energetic particle intensities at V2 show temporally
  coherent variations over a broad range of species and energies: from
  suprathermal ions (10s of keV) to galactic cosmic rays (&gt;1 GeV),
  as well as electrons from 10s of keV to &gt;100 MeV, corresponding to
  a range ~10<SUP>4</SUP> in particle gyroradii. Here we suggest that
  many of the intensity variations of energetic particle populations in
  the heliosheath are organized by their proximity to two fundamentally
  different regions—the unipolar heliosheath (UHS) and the sectored
  heliosheath (SHS). The SHS is a region of enhanced particle intensities,
  wherein particle transport, acceleration, and magnetic connectivity
  differ from those in the UHS. The SHS may serve as either a reservoir
  of energetic particles or as a region of enhanced transport, depending
  on the particle species and energy. Comparatively, particle intensities
  in the UHS are greatly reduced. We propose that the boundary between
  the SHS and UHS plays as important a role in the physics of heliosheath
  particles and fields as do the termination shock and heliopause.

---------------------------------------------------------
Title: Study of solar cycle effects in the heliosheath in the model
    based on SWAN/SOHO and IPS data at 1 AU
Authors: Provornikova, Elena; Richardson, John; Opher, Merav; Toth,
   Gabor; Izmodenov, Vladislav
2014cosp...40E2636P    Altcode:
  Observations of plasma in the heliosheath by Voyager 1 and 2 showed
  highly variable and very different plasma flows. Voyager 2 has been
  observing nearly constant radial flow ~110 km/s indicating that
  the spacecraft is still far from the heliopause. Plasma velocity
  components determined from LECP on Voyager 1 rapidly decreased across
  the heliosheath to zero values in the stagnation region near the
  HP. Steady state models of the outer heliosphere do not explain such
  different flows. These puzzling observational data motivate us to
  explore different physical effects at the edges of the heliosphere in
  the models. In this work we focus on time-dependent effects related to
  11- year solar cycle. We use a 3D MHD multi-fluid model of interaction
  of the solar wind with the local interstellar medium (BATSRUS) with
  time-dependent boundary conditions for the supersonic solar wind. Used
  realistic boundary conditions (plasma density and velocity) at 1 AU were
  derived from the measurements of intensities of Lyman-alpha emission
  on SOHO/SWAN, OMNI data (in the ecliptic plane) and interplanetary
  scintillations data over two full solar cycles. We present results of
  the time-dependent model and discuss effects of realistic variations
  of the solar wind parameters on the flow in the heliosheath and in the
  vicinity of the heliopause. From comparison of model results with the
  Voyager 1 and 2 observations we found that the solar cycle effects can
  explain constant radial flow along the Voyager 2 but do not reproduce
  the decrease of radial flow to zero seen at Voyager 1.

---------------------------------------------------------
Title: On the Rotation the Interstellar Magnetic Field Ahead of
    the Heliopause
Authors: Opher, Merav; Drake, James
2014cosp...40E2381O    Altcode:
  Based on the difference between the orientation of the interstellar and
  the solar magnetic fields, there was an expectation by the community
  that the magnetic field direction will rotate dramatically across the
  heliopause (HP). Recently, the Voyager team concluded that Voyager 1
  (V1) crossed into interstellar space last year. The question is then
  why there was no significant rotation in the direction of the magnetic
  field across the HP. Here we present simulations that reveal that
  strong rotations in the direction of the magnetic field at the HP at
  the location of V1 (and Voyager 2) are not expected. The solar magnetic
  field strongly affects the draping of the interstellar magnetic field
  (BISM) around the HP. BISM twists as it approaches the HP and acquires
  a strong T component (East-West). The strong increase in the T component
  occurs where the interstellar flow stagnates in front of the HP. At this
  same location the N component BN is significantly reduced. Above and
  below, the neighboring BISM lines also twist into the T direction. This
  behavior occurs for a wide range of orientations of BISM. The angle
  delta = a sin(BN /B) is small (around 10(°) -20(°) ), as seen in the
  observations. Only after some significant distance outside the HP is the
  direction of the interstellar field distinguishably different from that
  of the Parker spiral. In the twist region (after the HP) there is a fast
  variation of the angle delta/AU and then a slower one farther away as
  seen in the observations (Burlaga &amp; Ness 2014). We will discuss,
  as well in this talk, the mechanism responsible for the twist. The
  same twist is seen ahead of the magnetopause, where the field in the
  magnetosheath (equivalent to BISM) (in cases where reconnection is
  small) rotates toward the direction of the magnetospheric magnetic field
  (equivalent to the HS magnetic field) well upstream of the magnetopause
  (Phan et al. 1994). The IBEX ribbon, the band of increased intensity
  of energetic neutral atoms at 1 keV in the outer heliosphere, was
  originally believed to be aligned with the BISM · r = 0 just outside
  the HP. These results indicate that the draping of BISM is strongly
  influenced by the solar magnetic field. Only beyond ≈10 AU outside
  the HP is the centroid of the band of BISM · r = 0 is aligned with
  the original BISM direction.

---------------------------------------------------------
Title: Interactions between exoplanets and the winds of young stars
Authors: Vidotto, A. A.; Opher, M.; Jatenco-Pereira, V.; Gombosi, T. I.
2014EPJWC..6404006V    Altcode:
  The topology of the magnetic field of young stars is important
  not only for the investigation of magnetospheric accretion, but
  also responsible in shaping the large-scale structure of stellar
  winds, which are crucial for regulating the rotation evolution of
  stars. Because winds of young stars are believed to have enhanced
  mass-loss rates compared to those of cool, main-sequence stars, the
  interaction of winds with newborn exoplanets might affect the early
  evolution of planetary systems. This interaction can also give rise
  to observational signatures which could be used as a way to detect
  young planets, while simultaneously probing for the presence of their
  still elusive magnetic fields. Here, we investigate the interaction
  between winds of young stars and hypothetical planets. For that, we
  model the stellar winds by means of 3D numerical magnetohydrodynamic
  simulations. Although these models adopt simplified topologies of the
  stellar magnetic field (dipolar fields that are misaligned with the
  rotation axis of the star), we show that asymmetric field topologies can
  lead to an enhancement of the stellar wind power, resulting not only
  in an enhancement of angular momentum losses, but also intensifying
  and rotationally modulating the wind interactions with exoplanets.

---------------------------------------------------------
Title: Do all CMEs deflect to the background magnetic minimum by 4Rs?
Authors: Kay, Christina; Opher, Merav
2014cosp...40E1437K    Altcode:
  Accurate space weather forecasting requires knowledge of the trajectory
  of coronal mass ejections (CMEs), including any CME deflection close to
  the Sun or through interplanetary space. Kay et al. (2013) introduced
  ForeCAT, a model of CME deflection resulting from the background solar
  magnetic field. For a magnetic background corresponding to Carrington
  Rotation (CR) 2029 (declining phase, April-May 2005), the majority
  of the CMEs deflected to the streamer belt, the minimum in magnetic
  pressure. Most of the deflection occurred below 4 Rs. Here we explore
  the questions: a) Do all CMEs deflect to the magnetic minimum? and b)
  Does most deflection occur within 4 Rs? We have eliminated many of the
  underlying simplifications of ForeCAT presented in Kay et al. (2013)
  with a more detailed three dimensional description of the deflecting
  flux rope. The locations of coronal magnetic structures that determine
  the background magnetic minima vary throughout the solar cycle. We
  show that these variations reproduce observed trends in the direction
  of CME deflections throughout the solar cycle. We further explore the
  sensitivity of deflections to changes in the background magnetic minima
  at distances 1-2Rs guided by polarizations measures by instruments such
  ComP. Such deflections could be a probe of the lower corona background
  at these small distances.

---------------------------------------------------------
Title: On the Rotation of the Magnetic Field Across the Heliopause
Authors: Opher, M.; Drake, J. F.
2013ApJ...778L..26O    Altcode: 2013arXiv1310.0808O
  Based on the difference between the orientation of the interstellar and
  the solar magnetic fields, there was an expectation by the community
  that the magnetic field direction will rotate dramatically across the
  heliopause (HP). Recently, the Voyager team concluded that Voyager 1
  (V1) crossed into interstellar space last year. The question is then
  why there was no significant rotation in the direction of the magnetic
  field across the HP. Here we present simulations that reveal that
  strong rotations in the direction of the magnetic field at the HP
  at the location of V1 (and Voyager 2) are not expected. The solar
  magnetic field strongly affects the drapping of the interstellar
  magnetic field (B <SUB>ISM</SUB>) around the HP. B <SUB>ISM</SUB>
  twists as it approaches the HP and acquires a strong T component
  (East-West). The strong increase in the T component occurs where the
  interstellar flow stagnates in front of the HP. At this same location
  the N component B<SUB>N</SUB> is significantly reduced. Above and
  below, the neighboring B <SUB>ISM</SUB> lines also twist into the T
  direction. This behavior occurs for a wide range of orientations of B
  <SUB>ISM</SUB>. The angle δ = asin (B<SUB>N</SUB> /B) is small (around
  10°-20°), as seen in the observations. Only after some significant
  distance outside the HP is the direction of the interstellar field
  distinguishably different from that of the Parker spiral.

---------------------------------------------------------
Title: Global Numerical Modeling of Energetic Proton Acceleration
    in a Coronal Mass Ejection Traveling through the Solar Corona
Authors: Kozarev, Kamen A.; Evans, Rebekah M.; Schwadron, Nathan A.;
   Dayeh, Maher A.; Opher, Merav; Korreck, Kelly E.; van der Holst, Bart
2013ApJ...778...43K    Altcode: 2014arXiv1406.2377K
  The acceleration of protons and electrons to high (sometimes
  GeV/nucleon) energies by solar phenomena is a key component of
  space weather. These solar energetic particle (SEP) events can damage
  spacecraft and communications, as well as present radiation hazards to
  humans. In-depth particle acceleration simulations have been performed
  for idealized magnetic fields for diffusive acceleration and particle
  propagation, and at the same time the quality of MHD simulations of
  coronal mass ejections (CMEs) has improved significantly. However,
  to date these two pieces of the same puzzle have remained largely
  decoupled. Such structures may contain not just a shock but also
  sizable sheath and pileup compression regions behind it, and may vary
  considerably with longitude and latitude based on the underlying
  coronal conditions. In this work, we have coupled results from a
  detailed global three-dimensional MHD time-dependent CME simulation to
  a global proton acceleration and transport model, in order to study
  time-dependent effects of SEP acceleration between 1.8 and 8 solar
  radii in the 2005 May 13 CME. We find that the source population is
  accelerated to at least 100 MeV, with distributions enhanced up to
  six orders of magnitude. Acceleration efficiency varies strongly along
  field lines probing different regions of the dynamically evolving CME,
  whose dynamics is influenced by the large-scale coronal magnetic field
  structure. We observe strong acceleration in sheath regions immediately
  behind the shock.

---------------------------------------------------------
Title: Probing the Nature of the Heliosheath with the Neutral Atom
    Spectra Measured by IBEX in the Voyager 1 Direction
Authors: Opher, M.; Prested, C.; McComas, D. J.; Schwadron, N. A.;
   Drake, J. F.
2013ApJ...776L..32O    Altcode:
  We are able to show by comparing modeled energetic neutral atoms (ENAs)
  spectra to those measured by Interstellar Boundary Explorer (IBEX) that
  the models along the Voyager 1 (V1) trajectory that best agree with
  the low energy IBEX data include extra heating due to ram and magnetic
  energy in the quasi-stagnation region or a kappa ion distribution
  (with κ = 2.0) in the outer heliosheath. The model explored is the
  multi-ion, multi-fluid (MI-MF) which treats the pick-up ions and the
  thermal ion fluids with separate Maxwellian distributions. These effects
  are included ad hoc in the modeled ENA since they are not present
  in the model. These results indicate that the low energy spectra of
  ENAs as measured by IBEX is sensitive to the physical nature of the
  heliosheath and to effects not traditionally present in current global
  models. Therefore, by comparing the low energy ENA spectra to models,
  we can potentially probe the heliosheath in locations beyond those
  probed by V1 and Voyager 2 (V2).

---------------------------------------------------------
Title: A Porous, Layered Heliopause
Authors: Swisdak, M.; Drake, J. F.; Opher, M.
2013ApJ...774L...8S    Altcode: 2013arXiv1307.0850S
  The picture of the heliopause (HP)—the boundary between the domains
  of the Sun and the local interstellar medium (LISM)—as a pristine
  interface with a large rotation in the magnetic field fails to describe
  recent Voyager 1 (V1) data. Magnetohydrodynamic (MHD) simulations of
  the global heliosphere reveal that the rotation angle of the magnetic
  field across the HP at V1 is small. Particle-in-cell simulations,
  based on cuts through the MHD model at V1's location, suggest that
  the sectored region of the heliosheath (HS) produces large-scale
  magnetic islands that reconnect with the interstellar magnetic field
  while mixing LISM and HS plasma. Cuts across the simulation reveal
  multiple, anti-correlated jumps in the number densities of LISM and HS
  particles, similar to those observed, at the magnetic separatrices. A
  model is presented, based on both the observations and simulations,
  of the HP as a porous, multi-layered structure threaded by magnetic
  fields. This model further suggests that contrary to the conclusions
  of recent papers, V1 has already crossed the HP.

---------------------------------------------------------
Title: Forecasting a Coronal Mass Ejection's Altered Trajectory:
    ForeCAT
Authors: Kay, C.; Opher, M.; Evans, R. M.
2013ApJ...775....5K    Altcode: 2013arXiv1307.7603K
  To predict whether a coronal mass ejection (CME) will impact Earth,
  the effects of the background on the CME's trajectory must be taken
  into account. We develop a model, ForeCAT (Forecasting a CME's Altered
  Trajectory), of CME deflection due to magnetic forces. ForeCAT includes
  CME expansion, a three-part propagation model, and the effects of drag
  on the CME's deflection. Given the background solar wind conditions,
  the launch site of the CME, and the properties of the CME (mass, final
  propagation speed, initial radius, and initial magnetic strength),
  ForeCAT predicts the deflection of the CME. Two different magnetic
  backgrounds are considered: a scaled background based on type II
  radio burst profiles and a potential field source surface (PFSS)
  background. For a scaled background where the CME is launched from
  an active region located between a coronal hole and streamer region,
  the strong magnetic gradients cause a deflection of 8.°1 in latitude
  and 26.°4 in longitude for a 10<SUP>15</SUP> g CME propagating out to
  1 AU. Using the PFSS background, which captures the variation of the
  streamer belt (SB) position with height, leads to a deflection of 1.°6
  in latitude and 4.°1 in longitude for the control case. Varying the
  CME's input parameters within observed ranges leads to the majority
  of CMEs reaching the SB within the first few solar radii. For these
  specific backgrounds, the SB acts like a potential well that forces
  the CME into an equilibrium angular position.

---------------------------------------------------------
Title: Coronal Mass Ejection Plasma Heating by Alfven Wave Dissipation
Authors: Evans, Rebekah M.; Opher, M.; Van Der Holst, B.
2013SPD....4410401E    Altcode:
  Recent studies suggest that the thermal energy input into a coronal
  mass ejection is comparable to the kinetic energy. The dissipation
  of magnetic energy is thought to be the source of this heating. One
  possible mechanism, the dissipation of Alfven waves, has generally
  been neglected because heating rates calculated from models of the fast
  solar wind are orders of magnitude less than what is required to match
  CME plasma observations. Using new a three-dimensional solar wind model
  driven by Alfven waves within the Space Weather Modeling Framework, we
  simulate eruptions in the low to middle corona. The goal is to explore
  the self-consistent heating of CME plasma by wave dissipation. We find
  that the expansion of a flux rope can create regions of enhanced plasma
  density at the back of the sheath, which we call piled-up compression
  (PUC) regions. The Alfven wave energy is also enhanced in the sheath,
  where surface Alfven wave damping due to the density gradients
  dissipates the wave energy. This heating rate is orders of magnitude
  larger than the heating rate in the fast solar wind, which suggests
  that Alfven wave dissipation may play a role in CME plasma heating.

---------------------------------------------------------
Title: Plasma flow in the outer heliosphere due to variations of
    the solar wind structure at 1 AU in 11-year solar cycle
Authors: Provornikova, Elena; Opher, Merav; Izmodenov, Vlad; Toth,
   Gabor
2013shin.confE..67P    Altcode:
  Recent observations at Voyager 1 and 2 in the heliosheath - region
  of hot subsonic solar wind flow at the heliosphere boundary - show
  complex and very different plasma flows. Voyager 2 has been observing
  a constant radial flow 110 km/s indicating that the spacecraft is far
  from the heliopause. Meanwhile, in 2011 Voyager 1 entered a stagnation
  region at 120 AU with small/near-zero flow velocity components meaning
  that Voyager 1 may be very close to the HP. Steady state models of the
  outer heliosphere do not explain such different flows. These puzzling
  observational data motivate us to explore different physical effects
  at the edges of the heliosphere in the models. In this work we focus
  on time-dependent effects related to 11- year solar cycle. We use a
  global 3D MHD multi-fluid model of interaction of the solar wind with
  the local interstellar medium with time-dependent boundary conditions
  for the supersonic solar wind. Realistic boundary conditions (plasma
  density and velocity) at 1 AU were obtained from the measurements of
  intensities of Lyman-alpha emission on SOHO/SWAN, OMNI data (in the
  ecliptic plane) and interplanetary scintillations data over two full
  solar cycles. We present results of the time-dependent model and discuss
  effects of realistic variations of the solar wind parameters on the
  flow in the heliosheath and in the vicinity of the heliopause. From
  comparison of model results with the Voyager 1 and 2 observations we
  found that the solar cycle effects can explain constant radial flow
  along the Voyager 2 but do not reproduce the decrease of radial flow
  to zero seen at Voyager 1.

---------------------------------------------------------
Title: Predicting CME Deflections Using ForeCAT
Authors: Kay, Christina Danielle; Opher, M.; Evans, R. M.
2013shin.confE..73K    Altcode:
  To predict whether a coronal mass ejection (CME) will impact Earth,
  the effects of the background on the CME's trajectory must be taken
  into account. We developed a model, ForeCAT (Forecasting a CME's Altered
  Trajectory), of CME deflection due to magnetic forces. ForeCAT includes
  CME expansion, a three-part propagation model, and the effects of drag
  on the CME's deflection. Given the background solar wind conditions,
  the launch site of the CME, and the properties of the CME (mass, final
  propagation speed, initial radius, and initial magnetic strength),
  ForeCAT predicts the deflection of the CME. Two different magnetic
  backgrounds are considered: a scaled magnetic background and a
  Potential Field Source Surface (PFSS) background. The scaled magnetic
  background scales with distance as R^-2 (for quiet sun) and R^-3 (for
  active regions). The magnetic field in the PFSS description falls much
  quicker but captures the variation of features with height, such as
  the streamer belt position. The CME is launched from an active region
  located between a CH and streamer region and the magnetic gradients
  deflect the CME towards the minimum in magnetic intensity. For this
  background with strong magnetic gradients, the streamer belt acts
  as a potential well that forces the CME into an equilibrium angular
  position when only magnetic forces are considered. For the scaled
  magnetic background this leads to deflection of 8.1° in latitude and
  26.4° in longitude for a CME with initial mass 10^15 g. For the PFSS
  background, in turn the deflection is much smaller, 1.6° in latitude
  and 4.1° in longitude. ForeCAT shows that magnetic forces alone can
  reproduce deflections of comparable magnitude to those observed in
  coronagraph images. Future work will explore further the effects of
  different magnetic backgrounds and many of the underlying assumptions
  in ForeCAT and provide comparisons with observed deflections.

---------------------------------------------------------
Title: Features of coronal SEP acceleration in a globally modeled
    realistic CME
Authors: Kozarev, Kamen Asenov; Evans, Rebekah; Schwadron, Nathan;
   Opher, Merav; Korreck, Kelly
2013shin.confE.133K    Altcode:
  The next generation of solar exploratory missions (Solar Probe Plus
  and Solar Orbiter) will probe the plasma and particle conditions
  near the Sun directly. Recent studies suggest that solar energetic
  particles (SEP) may gain most of their energy at coronal mass ejection
  (CME)-driven shocks relatively close to the Sun, and therefore a
  better understanding of these acceleration processes in the corona is
  necessary. The rapidly varying conditions in the corona during CMEs,
  and the highly compressed sheaths that may form in front of ejecta,
  likely enable rapid particle acceleration to high energies. By combining
  a realistic time-dependent MHD model of a CME in the low and middle
  corona (SWMF) with a global kinetic acceleration and transport model
  (EPREM), we address two important questions concerning coronal SEP
  acceleration: 1) How do changes in the CME plasma environment influence
  local adiabatic acceleration on open field lines? 2) What role does
  stochastic acceleration play in coronal SEP creation?

---------------------------------------------------------
Title: A slow bow shock ahead of the heliosphere
Authors: Zieger, B.; Opher, M.; Schwadron, N. A.; McComas, D. J.;
   Tóth, G.
2013GeoRL..40.2923Z    Altcode:
  Current estimates of plasma parameters in the local interstellar
  medium indicate that the speed of the interstellar wind, i.e.,
  the relative speed of the local interstellar cloud with respect to
  the Sun, is most likely less than both the fast magnetosonic speed
  (subfast) and the Alfvén speed (sub-Alfvénic) but greater than
  the slow magnetosonic speed (superslow). In this peculiar parameter
  regime, MHD theory postulates a slow magnetosonic shock ahead of the
  heliosphere, provided that the angle between the interstellar magnetic
  field and the interstellar plasma flow velocity is quite small (e.g.,
  15° to 30°). In this likely scenario, our multifluid MHD model of
  the heliospheric interface self-consistently produces a spatially
  confined quasi-parallel slow bow shock. Voyager 1 is heading toward
  the slow bow shock, while Voyager 2 is not, which means that the two
  spacecraft are expected to encounter different interstellar plasma
  populations beyond the heliopause. The slow bow shock also affects
  the density and spatial extent of the neutral hydrogen wall.

---------------------------------------------------------
Title: Global Modeling of the July 23, 2012 Coronal Mass Ejection
    and Solar Energetic Particle Event
Authors: Evans, Rebekah Minnel; Kozarev, Kamen A.; Schwadron, Nathan
   A.; Opher, Merav; Manchester, Ward; Sokolov, Igor; van der Holst, Bart
2013shin.confE...7E    Altcode:
  The CME and SEP event of July 23, 2012 was extreme in many ways - the
  speed of a CME as imaged in coronagraphs, the speed and magnetic field
  strength measured in-situ, and the level of energetic particles. Another
  special feature of this event is that it caused SEP events at Earth,
  STEREO A and STEREO B, which were very separated at the time. The
  extreme and whole-heliosphere nature of this event makes it an
  excellent candidate to study with two recently coupled models: the
  Space Weather Modeling Framework (SWMF) and the Energetic Particle
  Radiation Environment Module (EPREM). The SWMF, which itself couples
  three-dimensional magnetohydrodynamic (MHD) models describing the solar
  corona and heliosphere, is used to simulate the eruption starting
  from the low corona. The MHD output describing the fast CME event
  is coupled to a global kinetic simulation of particle acceleration
  and transport within EPREM. The output of the particle simulation is
  synthetic time-dependent spectra influenced by the dynamics of CME
  structures that form self-consistently during propagation. With these
  simulations, we can probe how the properties of the CME sheath and shock
  vary as the CME interacts with the ambient corona and heliosphere. These
  simulations can test current theories of SEP production, including
  how SEP properties relate to the properties of the associated CME,
  CME-driven shock and coronal environment. Finally, we can trace how
  particles that interacted with the CME near the Sun propagate throughout
  the heliosphere.

---------------------------------------------------------
Title: Magnetic reconnection in the interior of interplanetary
    coronal mass ejections
Authors: Fermo, Raymond Luis; Opher, Merav; Drake, James F.
2013shin.confE..69F    Altcode:
  Recent in situ observations of interplanetary coronal mass ejections
  (ICMEs) found signatures of reconnection exhausts in their interior
  or trailing edge. Whereas reconnection on the leading edge of an ICME
  would indicate an interaction with the coronal or interplanetary
  environment, this result suggests that the internal magnetic field
  reconnects with itself. In light of this data, we consider some of the
  physics developed by the fusion plasma community. In the context of a
  tokamak, Taylor showed that the lowest energy state corresponds to one
  in which curl B = lambda B with constant lambda, the so-called Taylor
  state. Variations from this state will result in the magnetic field
  trying to re-orient itself into the Taylor state solution, subject
  to the constraints that the toroidal flux and magnetic helicity are
  invariant. This relaxation is mediated by the reconnection of magnetic
  field lines along rational surfaces, that is, flux surfaces where the
  safety factor q = m/n for integer m and n. In tokamaks, the result is
  a "sawtooth crash" te{Kadomtsev75b}. In an ICME, if we likewise treat
  the flux rope as a toroidal flux tube, any variation from the Taylor
  state will result in reconnection within the interior of the flux tube,
  in agreement with the observation by Gosling et al (2007). One such
  way in which the Taylor state might be violated is by the elongation
  of the flux tube cross section in the non-radial direction, as seen
  in magnetohydrodynamic (MHD) simulations of flux tubes propagating
  through the interplanetary medium. We show analytically that this this

---------------------------------------------------------
Title: Time-dependent solar wind flows in the heliosheath
Authors: Provornikova, E.; Opher, M.; Izmodenov, V.; Toth, G.
2013AGUSMSH21A..02P    Altcode:
  Recent observations on Voyager 1 and 2 spacecraft show complex and
  very different solar wind flows in the heliosheath region. Voyager
  2 has been observing constant radial flows (Richardson and Wang
  2013). At the beginning of 2011 Voyager 1 entered a region with zero
  and even negative radial velocity of the plasma flow (Krimigis et
  al. 2011). Since mid 2012 Voyager 1 continues observing a new region
  in the heliosheath with fast changing of intensities of anomalous and
  galactic cosmic rays. These puzzling observational data motivate us
  to explore different physical effects at the edges of the heliosphere
  in the models. In order to separate spatial from temporal effects the
  investigation of time-dependent effects are crucial. In this work we
  focus on time-dependent effects of the 11-year solar cycle. We use
  a global MHD multi-fluid model of interaction of the solar wind with
  the local interstellar medium with time-dependent boundary conditions
  for the supersonic solar wind. Realistic boundary conditions (plasma
  density and velocity) at 1 AU for the plasma were obtained from the
  measurements of Ly-alpha intensities on SOHO/SWAN, OMNI data and
  interplanetary scintillations data. We present effects of realistic
  variations of the solar wind dynamic pressure on the solar wind flow in
  the heliosheath and in the vicinity of the heliopause. Comparing the
  results of time-dependent model along the Voyager 1 and 2 trajectory
  with observational data we describe effects of solar cycle on the
  flows that Voyager measures.

---------------------------------------------------------
Title: The Slow Bow Shock Model of the Heliospheric Interface
Authors: Zieger, B.; Opher, M.
2013AGUSMSH24A..04Z    Altcode:
  Recent IBEX observations indicate that the pristine interstellar
  wind is most likely subfast and sub-Alfvenic, which means that
  no regular fast magnetosonic bow shock can form upstream of the
  heliosphere. Nevertheless, a slow magnetosonic bow shock can still exist
  in the local interstellar medium, provided that the angle between the
  interstellar magnetic field and the interstellar plasma flow velocity
  (alpha_Bv) is sufficiently small. The latter is supported by a number
  of kinetic-gasdynamic and multi-fluid MHD simulations that used the
  Voyager termination shock crossings to constrain the magnitude (3 to 4
  microG) and direction (alpha_Bv= 15 to 30 degrees) of the interstellar
  magnetic field. We propose a quasi-parallel slow bow shock model as a
  likely alternative of the currently prevailing no bow shock model. The
  theoretically expected slow bow shock is self-consistently reproduced
  in our multi-fluid MHD simulations. Since slow-mode information
  can propagate mainly along the magnetic field, the slow bow shock is
  significantly shifted from the nose of the heliosphere toward the flank
  in the direction of the interstellar magnetic field. Such a displaced
  slow bow shock results in a dense and highly asymmetric hydrogen wall
  that is expected to produce detectable extra Lyman alpha absorption not
  only around the nose direction but also in some preferential tailward
  directions. This could explain among others the puzzling blue shift
  observed in the Lyman alpha absorption profile of Sirius. The slow
  bow shock model could easily explain the hotter and slower secondary
  interstellar hydrogen population observed by IBEX, which is thought to
  originate from the outer heliosheath. Thus both Lyman alpha and IBEX
  observations seem to be more consistent with a slow bow shock rather
  than a shock-free fast bow wave. Voyager 1 is most likely heading
  towards the slow bow shock, while Voyager 2 is not, which means that
  the two spacecraft are expected to encounter fundamentally different
  interstellar plasma populations beyond the heliopause.

---------------------------------------------------------
Title: Structure of the Heliosheath and Heliopause
Authors: Opher, M.; Drake, J. F.; Swisdak, M. M.; Toth, G.
2013AGUSMSH24A..06O    Altcode:
  We discuss the structure of the heliosheath (HS) and and heliopause (HP)
  when reconnection is taken place within the sector region. Observational
  constrains of reconnection within the sector are challenged by
  the resolution limitations of the magnetometer. However, indirect
  constraints such as the lack of conservation of magnetic flux in
  the heliosheath (Richardson et al. 2013) and the correlation of the
  variability of energetic particles with the sector region (Hill et
  al. 2013) indicate that reconnection might be taking place within
  the sector (Opher et al. 2011). The reconnected sector region in
  high beta plasma has a multitude of islands and is very similar to
  a crossing of a normal sector in terms of the overall configuration
  of the magnetic field and intensity. However, there is substantial
  reduction of magnetic tension. We show, that Rayleigh-Taylor (RT)
  instabilities can take place within the sector region where there is
  no magnetic tension to stabilize the interchange instability (Opher et
  al. 2013). The RT instability produces elongated flow structures that
  disturb the heliosheath flow pattern. This instability can explain the
  large differences between the flows at Voyager 1 and 2. V1 measurements
  indicate a constant decrease in the radial speed until a region with
  zero radial speeds while V2 radial speeds are constant. The structure of
  the HP has been explored with 2-D PIC simulations (Swisdak et al. 2013)
  to understand what underlies the complex particle and magnetic data
  seen by V1 in the latter half of 2012. We show using a global MHD
  model that because of draping the direction of the magnetic field
  in the interstellar medium (ISM) does not differ significantly from
  the azimuthal heliospheric field measured in the HS. Magnetic field
  profiles from cuts of the MHD simulation across the HP are used as
  input into the initial conditions of the PIC simulation. However, the
  HS in the PIC simulation is taken to have a sectored structure with a
  population of pickup ions.The sectored field reconnects first, forming
  magnetic islands with scales of the order of the sector spacing. These
  islands then begin reconnecting with the ISM across the HP, slowed
  by the higher density plasma in the ISM. The HP eventually develops a
  complex magnetic structure with nested magnetic islands where HS and
  ISM plasma has mixed. Multiple sharp jumps in the number density of
  the ISM plasma are seen in cuts across the HP which is revealed not
  as a single boundary but as a series of boundaries. The jumps occur at
  separatrices of magnetic islands that exhibit jumps in the population
  density but no jumps in the magnetic field direction. This important
  result is consistent with the striking absence of rotation of the
  magnetic field data seen during jumps in the ACR and GCR intensities
  seen by V1. Based on these simulation results and the Voyager magnetic
  and particle data we have constructed the possible magnetic structure
  of the HP boundary region, which includes a series of nested magnetic
  islands and separatrices, that produce a porous boundary. The jump
  in the magnetic field strength measured by Voyager on its approach to
  the HP very likely arises from the leakage of high pressure HS plasma
  across this porous boundary into the ISM where it is lost.

---------------------------------------------------------
Title: Update from the BU-CME Group: Accurate Prediction of CME
    Deflection and Magnetic reconnection in the interior of interplanetary
    CMEs
Authors: Opher, M.; Kay, C.; Fermo, R. L.; Drake, J. F.; Evans, R. M.
2013AGUSMSH23B..02O    Altcode:
  The accurate prediction of the path of coronal mass ejections (CMEs)
  plays an important role in space weather forecasting, and knowing
  the source location of the CME does not always suffice. During
  solar minimum, for example, polar coronal holes (CHs) can deflect
  high latitude CMEs toward the ecliptic plane and when CHs extend to
  lower latitudes deflections in other directions can occur. To predict
  whether a CME will impact Earth the effects of the solar background
  on the CME's trajectory must be taken into account. Here we develop a
  model (Kay et al. 2013), called ForeCAT (Forecasting a CME's Altered
  Trajectory), of CME deflection close to the Sun where magnetic forces
  dominate. Given the background solar wind conditions, the launch
  site of the CME, and the properties of the CME (such as its mass and
  size), ForeCAT predicts the deflection of the CME as well as the full
  trajectory as the CME propagates away from the Sun. For a magnetic
  background where the CME is launched from an active region located in
  between a CH and streamer region the strong magnetic gradients cause
  a deflection of 39.0<SUP>o</SUP> in latitude and 21.9<SUP>o</SUP>
  in longitude. Varying the CME's input parameters within observed
  ranges leads to deflections predominantly between 36.2<SUP>o</SUP>
  and 44.5<SUP>o</SUP> in latitude and between 19.5<SUP>o</SUP> and 27.9
  in longitude. For all cases, the majority of the deflection occurs
  before the CME reaches a radial distance of 3 R⊙. Recent in situ
  observations of interplanetary mass ejections (ICMEs) found signatures
  of reconnection exhausts in their interior or trailing edge. This result
  suggests that the internal magnetic field reconnects with itself. To
  this end, we propose an approach (Fermo et al. 2013) borrowed from
  the fusion plasma community. Taylor (1974) showed that the lowest
  energy state corresponds to one in which \grad × B = λ B. Variations
  from this state will result in the magnetic field trying to re-orient
  itself into the Taylor state solution, subject to the constraints that
  the toroidal flux and magnetic helicity are invariant. In tokamaks,
  the result is a sawtooth crash. In an ICME, if we likewise treat the
  flux rope as a toroidal flux tube, any variation from the Taylor state
  will result in reconnection within the interior of the flux tube,
  in accord with the observations by Gosling et al. (2007). We present
  MHD and PIC simulations that shows that indeed this is the case and
  discuss the implications for ICMEs.

---------------------------------------------------------
Title: Propagation into the heliosheath of a large-scale solar wind
    disturbance bounded by a pair of shocks
Authors: Provornikova, E.; Opher, M.; Izmodenov, V.; Toth, G.
2013A&A...552A..99P    Altcode: 2013arXiv1303.5105P
  Context. After the termination shock (TS) crossing, the Voyager
  2 spacecraft has been observing strong variations of the magnetic
  field and solar wind parameters in the heliosheath. Anomalous cosmic
  rays, electrons, and galactic cosmic rays present strong intensity
  fluctuations. Several works suggested that the fluctuations might be
  attributed to spatial variations within the heliosheath. Additionally,
  the variability of the solar wind in this region is caused by different
  temporal events that occur near the Sun and propagate to the outer
  heliosphere. <BR /> Aims: To understand the spatial and temporal
  effects in the heliosheath, it is important to study these effects
  separately. In this work we explore the role of shocks as one type
  of temporal effects in the dynamics of the heliosheath. Although
  currently plasma in the heliosheath is dominated by solar minima
  conditions, with increasing solar cycle shocks associated with
  transients will play an important role. <BR /> Methods: We used a
  3D MHD multi-fluid model of the interaction between the solar wind
  and the local interstellar medium to study the propagation of a pair
  of forward-reverse shocks in the supersonic solar wind, interaction
  with the TS, and propagation to the heliosheath. <BR /> Results: We
  found that in the supersonic solar wind the interaction region between
  the shocks expands, the shocks weaken and decelerate. The fluctuation
  amplitudes of the plasma parameters vary with heliocentric distance. The
  interaction of the pair of shocks with the TS creates a variety of
  new waves and discontinuities in the heliosheath, which produce a
  highly variable solar wind flow. The collision of the forward shock
  with the heliopause causes a reflection of fast magnetosonic waves
  inside the heliosheath. <P />A movie is available in electronic form
  at <A href="http://www.aanda.org">http://www.aanda.org</A>

---------------------------------------------------------
Title: Magnetic Flux Conservation in the Heliosheath
Authors: Richardson, J. D.; Burlaga, L. F.; Decker, R. B.; Drake,
   J. F.; Ness, N. F.; Opher, M.
2013ApJ...762L..14R    Altcode:
  Voyager 1(V1) and Voyager 2(V2) have observed heliosheath plasma since
  2005 December and 2007 August, respectively. The observed speed profiles
  are very different at the two spacecrafts. Speeds at V1 decreased
  to zero in 2010 while the average speed at V2 is a constant 150 km
  s<SUP>-1</SUP> with the direction rotating tailward. The magnetic flux
  is expected to be constant in these heliosheath flows. We show that
  the flux is constant at V2 but decreases by an order of magnitude at
  V1, even after accounting for divergence of the flows and changes in
  the solar field. If reconnection were responsible for this decrease,
  the magnetic field would lose 70% of its free energy to reconnection
  and the energy density released would be 0.6 eV cm<SUP>-3</SUP>.

---------------------------------------------------------
Title: Intensities and spectral properties of 0.03-6 keV Energetic
    Neutral Atoms Measured by the Interstellar Boundary Explorer (IBEX)
    Along the Lines-of-Sight of Voyager
Authors: Desai, M. I.; Allegrini, F.; Dayeh, M. A.; DeMajistre, B.;
   Funsten, H. O.; Heerikhuisen, J.; McComas, D. J.; Pogorelov, N. V.;
   Prested, C. L.; Opher, M.; Schwadron, N. A.; Zank, G. P.; Fuselier,
   S. A.
2012AGUFMSH13D..08D    Altcode:
  Energetic Neutral Atoms (ENAs) observed by the Interstellar Boundary
  Explorer (IBEX) provide powerful diagnostics about the origin of the
  progenitor ion populations and the physical mechanisms responsible
  for their production. Here we survey the fluxes, energy spectra,
  and energy-dependence of the spectral indices of ~0.03-6 keV ENAs
  measured by IBEX-Hi and IBEX-Lo along the lines-of-sight of Voyager 1
  and 2. We compare the ENA spectra observed at IBEX with predictions of
  models that simulate the microphysics of the heliospheric termination
  shock to predict the shape and relative contributions of a variety
  of heliosheath ion populations. We show: (1) The ENA spectra between
  ~0.7-6 keV do not exhibit sharp cut-offs at ~twice the solar wind
  speed as is typically observed for shell-like PUI distributions in
  the heliosphere and are reasonably well accounted for by most of the
  models. (2) The 0.03-0.7 keV ENA intensities are larger by more than
  an order of magnitude compared with most existing models. We conclude
  that the 0.7-5 keV ENAs at IBEX are generated by transmitted PUIs
  in the ~0.5-5 keV energy range, the PUI distribution likely being
  a smoothed superposition of Maxwellian or kappa distributions and
  partially filled shell distributions in velocity space. In contrast,
  the origin of the heliosheath parent ion population for the &lt;0.7
  keV ENAs remains poorly understood and here we discuss possible causes
  of the discrepancy between IBEX observations and model predictions.

---------------------------------------------------------
Title: Global Numerical Modeling of SEP Acceleration by a CME Shock
    in the Solar Corona and Subsequent Transport to 1 AU
Authors: Kozarev, K. A.; Evans, R. M.; Schwadron, N. A.; Dayeh, M. A.;
   Opher, M.; van der Holst, B.
2012AGUFMSH23B..04K    Altcode:
  It has been suggested that solar energetic particles (SEP) may gain most
  of their energy at coronal mass ejection (CME)-driven shocks relatively
  close to the Sun. The observed and modeled Alfven speed profiles in the
  solar corona allow for fast shocks to develop within 10 solar radii. In
  addition, rapid changes occur in the ejected plasma structures and there
  is a great abundance of charged seed particles close to the Sun relative
  to the interplanetary populations. The combination of these conditions
  is favorable for the acceleration of large SEP fluxes, especially
  protons. However, the details of the acceleration process remain hidden
  due to the lack of in situ observations in the corona. As the next
  generation of solar exploratory missions (Solar Probe Plus and Solar
  Orbiter) gets ready to probe the plasma and particle conditions near
  the Sun directly, a better understanding of SEP acceleration processes
  in the corona is necessary. We have developed a comprehensive model for
  studying proton acceleration and global interplanetary transport. It
  consists of two parts: a three-dimensional magnetohydrodynamics (MHD)
  model of the solar corona and interplanetary space (part of the Space
  Weather Modeling Framework), which we use to simulate the corona,
  solar wind, and a CME; and a global energetic particle acceleration and
  transport kinetic model (the Energetic Particle Radiation Environment
  Module), which uses the results from the MHD simulation to model the
  time-dependent behavior of protons from the corona to 1 AU. We show that
  the shock and plasma structures may efficiently accelerate suprathermal
  protons to hundreds of MeV energies during their transit. We find that
  the resulting SEP spectra vary greatly depending on the location of
  their guiding field lines relative to the shock and CME.

---------------------------------------------------------
Title: How Structures of the Solar Corona and Eruptions Interact to
    Create Extreme Energetic Particle Events
Authors: Evans, R. M.; Kozarev, K. A.; Zheng, Y.; Pulkkinen, A.;
   Taktakishvili, A.; Kuznetsova, M. M.; Opher, M.; Dayeh, M. A.;
   Schwadron, N. A.; van der Holst, B.
2012AGUFMSH14A..06E    Altcode:
  As the Sun approaches maximum activity, the number of solar energetic
  particle (SEP) events is rapidly increasing. These strong events
  have the potential to damage technical systems, so it is essential to
  understand what causes them. Although relationships exist between the
  characteristics of SEP events and the associated flares and coronal mass
  ejections (CMEs), the strongest solar events may not lead to the most
  intense particle events. For example, the first Ground Level Enhancement
  event of Solar Cycle 24 was associated with only a moderately strong
  flare and CME. Presumably, there must be other factors that determine
  the acceleration of the highest energy particles. To address this
  question, we combine observations and innovative theoretical modeling
  of recent SEP events. We use a three-dimensional magnetohydrodynamics
  (MHD) model of the solar corona (within the Space Weather Modeling
  Framework) to simulate eruptions in the low to middle corona. The
  MHD output is coupled to a global kinetic simulation of particle
  acceleration and transport (within the Energetic Particle Radiation
  Environment Module). The output of the simulation is a synthetic
  spectral profile response to realistic solar corona conditions during
  the propagation of a CME. We study the evolution of the CME structures
  (shock and compression regions within the sheath) and the relation of
  these features to the preexisting coronal magnetic field geometry and
  solar wind distribution. Then we determine which factors affect the
  efficiency of particle acceleration and transport. For the first time,
  we can probe how particle acceleration varies in different regions of
  the CME as it interacts with the solar wind. R. M. E. is supported
  through an appointment to the NASA Postdoctoral Program at GSFC,
  administered by Oak Ridge Associated Universities through a contract
  with NASA.

---------------------------------------------------------
Title: Probing the Nature of the Heliosheath with the Heliospheric
    Neutral Atom Spectra Measured by IBEX in the Voyager 1 Direction
Authors: Opher, M.; Prested, C. L.; McComas, D. J.; Schwadron, N. A.;
   Toth, G.
2012AGUFMSH13D..04O    Altcode:
  The Interstellar Boundary Explorer (IBEX) has been making detailed
  observations of neutrals from the boundaries of the heliosphere from
  0.2-6 keV. Recent studies using the accumulated measurements of three
  years of observations extended the IBEX spectra down to lower energies
  (Fusielier et al. ApJ 2012). We compare the modeled ENA spectra to
  the ones measured by IBEX in order to explore the sensitivity to the
  heliosheath flows and temperatures along the Voyager 1 trajectory. The
  models explored are: (a) single-ion, multi-fluid (SI-MF) (Opher
  et al. 2009) that includes the ionized thermal plasma (solar wind
  plus pick-up ions (PUIs) plus the neutral H atoms) in a multi-fluid
  approximation; and our recent model (b) multi-ion, multi-fluid (MI-MF)
  that treats the PUIs and the thermal ions as separate fluids with
  maxwellian distributions (Prested et al. 2012). The use of a maxwellian
  distribution for the transmitted PUIs is supported by works such as
  Wu et al. (2010). Additionally, in the modeled ENA spectra we account
  for effects, not present in the models, from: a) the zero flows in
  the stagnation region (Decker et al. Nature 2012), as from our model
  that included the sector region (Opher et al. ApJ 2012) 15-20AU before
  the heliopause; b) extra heating in the stagnation region equivalent
  to the missing ram pressure; c) extra heating due to reconnection
  in the stagnation region (Drake et al. 2010; Opher et al. 2011);
  d) kappa ion distribution with power spectra (~ 1.5 - 2.0) in the
  heliosheath as produced by models such as Gloeckler and Fisk (2010);
  e) kappa ion distribution in the outer heliosheath. We find that the
  models that invoked extra heating in the stagnation region (as in case
  (b)-(c)) best agree with the low energy IBEX data. We evaluate model
  results in terms of the number of free parameters versus the level of
  agreement and comment on the implications of the models.

---------------------------------------------------------
Title: Reconnection at the Heliopause and Its Effects on the Transport
    of Energetic Particles
Authors: Swisdak, M. M.; Drake, J. F.; Opher, M.
2012AGUFMSH11A2195S    Altcode:
  At the heliopause the interstellar magnetic field abuts the sectored
  field of the heliosheath wherein, upstream of the heliopause, magnetic
  reconnection generates a bath of magnetic islands. Further reconnection
  can occur at the heliopause itself and provide a natural pathway
  for energetic particles (e.g., anomalous cosmic rays, ACRs, from
  within the heliosphere and galactic cosmic rays, GCRs, from without)
  to penetrate the boundary. Once within the heliosheath, interactions
  with magnetic islands strongly influence the motion of energetic
  particles. In order to investigate this scenario we have carried out
  kinetic particle-in-cell simulations (with initial conditions taken
  from a global heliospheric model) that self-consistently include a
  small number of energetic particles. We find that, after reconnection
  begins, particles diffuse across the heliopause --- ACRs are found
  in interstellar space and GCRs are found within the heliosheath. We
  trace the trajectories of representative energetic particles through
  this bath. We show that their propagation parallel to the magnetic
  field in the island-filled heliosheath is slower than through the more
  laminar interstellar field, while motions perpendicular to the field
  have the opposite tendencies. By the simulation's end the initially
  flat heliopause has been strongly distorted by the magnetic islands
  that have grown during reconnection and become porous, allowing the
  interstellar medium to access the heliosheath. We will discuss the
  implications of these findings for the Voyager 1 spacecraft, which is
  quickly approaching, and may soon pass, the heliopause.

---------------------------------------------------------
Title: Heavy Ion Heating from the Sun to 1AU
Authors: Korreck, K. E.; Lepri, S. T.; Kasper, J. C.; Case, A. W.;
   Kozarev, K. A.; Opher, M.; Evans, R. M.; Stevens, M. L.; Schwadron,
   N. A.
2012AGUFMSH51A2217K    Altcode:
  The heating of heavy ions at the Sun and as they travel through the
  interplanetary space is relevant to both identifying the solar wind
  source region as well as the overall heating mechanisms and kinetics
  of the solar wind. Using ACE SWICS data on heavy ions from the shock
  associated with a CME on May 13, 2005, we examine the heavy ion heating
  and non-thermal nature of the helium distributions at 1AU as well as
  bulk solar wind parameters around the time of the CME. We utilize
  current work on high resolution 3D MHD models to compare the bulk
  solar wind parameters from the Sun to the inner heliosphere with a
  CME input. The relationship between the model's parameters and the
  observations at different regions of interest i.e the Solar Probe
  and Solar Orbiter orbits will be extrapolated. This model will in the
  future be extended to quiescent times of the solar wind.

---------------------------------------------------------
Title: Reconnection in ICMEs by Relaxation into the Taylor State
Authors: Fermo, R. L.; Opher, M.; Drake, J. F.
2012AGUFMSH31A2199F    Altcode:
  Recent in situ observations of interplanetary mass ejections (ICMEs)
  found signatures of reconnection exhausts in their interior or trailing
  edge [Gosling et al., 2007]. Whereas reconnection on the leading
  edge of an ICME would indicate an interaction with the coronal or
  interplanetary environment, this result suggests that the internal
  magnetic field reconnects with itself. To this end, we propose an
  approach borrowed from the fusion plasma community. In the context of a
  tokamak, Taylor [1974] showed that the lowest energy state corresponds
  to one in which curl B = λB. Variations from this state will result
  in the magnetic field trying to re-orient itself into the Taylor state
  solution, subject to the constraints that the toroidal flux and magnetic
  helicity are invariant. This relaxation is mediated by the reconnection
  of magnetic field lines in the m=1 mode. In tokamaks, the result is a
  "sawtooth crash" [Kadomtsev, 1975]. In an ICME, if we likewise treat
  the flux rope as a toroidal flux tube, any variation from the Taylor
  state will result in reconnection within the interior of the flux tube,
  in accord with the observation by Gosling et al. [2007]. One such way
  in which the Taylor state might be violated is by the elongation of
  the flux tube cross section in the non-radial direction, as seen in
  MHD simulations of flux tubes propagating through the interplanetary
  medium. We show analytically that this this elongation results in a
  violation of the Taylor state criterion curl B = λB. Lastly, we shall
  present PIC simulations of an elongated flux tube which has deviated
  from the Taylor state.

---------------------------------------------------------
Title: CME Deflection Predictions Using ForeCAT (Forecasting a CME's
    Altered Trajectory)
Authors: Kay, C.; Opher, M.; Evans, R. M.; van der Holst, B.
2012AGUFMSH14A..02K    Altcode:
  The accurate prediction of the path of coronal mass ejections (CMEs)
  plays an important role in space weather forecasting, and knowing
  the source location of the CME does not always suffice. During solar
  minimum polar coronal holes (CHs) deflect high latitude CMEs toward
  the ecliptic and when CHs extend to lower latitudes other deflections
  can occur. To predict whether a CME will impact Earth, these nonideal
  effects must be taken into account. Our previous simulations of an
  erupting flux rope placed near a CH in the low corona indicate magnetic
  forces as the key driver behind these nonradial motions close to the
  Sun's surface. Here, we present a newly developed IDL routine ForeCAT
  (Forecasting a CME's Altered Trajectory) to predict the path of a
  CME. Given the background solar wind conditions, the launch site of the
  CME, and the properties of the CME (such as its magnetic energy), we
  forecast the deflection of the CME. Our model incorporates the effects
  of magnetic tension and magnetic pressure gradient forces acting on
  opposite edges of the CME as the primary drivers of the deflection,
  and the CME expands according to its magnetic energy. The strength of
  the magnetic pressure and tension forces results from the CME size
  and location with respect to various solar features such as CHs,
  active regions, or streamer regions. We also include the effects of
  drag as the edges propagate outward against the solar wind. For each
  edge, we numerically integrate the forces leading to a change in edge
  position. We present comparisons with previously observed deflection
  events and studies of the model's sensitivity to input parameters.

---------------------------------------------------------
Title: Solar wind flow in the heliosheath due to latitudinal and
    time variations over the solar cycle
Authors: Provornikova, E.; Opher, M.; Izmodenov, V.; Toth, G.
2012AGUFMSH11B2203P    Altcode:
  Recent observations by Voyager 2 in the heliosheath showed strong
  variations of the solar wind density, velocity and temperature. Magnetic
  field fluctuates considerably as observed on both Voyager 1 and
  2. Anomalous and galactic cosmic rays also present large fluctuations
  of intensity. Spatial variations and temporal effects in the solar
  wind due to solar cycle attribute to the observed fluctuations. In
  this work we aim to explore effects of realistic solar cycle on the 3D
  solar wind flow in the outer heliosphere. We use time and latitudinal
  variations of the solar wind density and velocity over two last solar
  cycles as the boundary conditions in a 3D MHD multi-fluid model of the
  interaction between the solar wind and interstellar medium based on
  BATSRUS code. These realistic boundary conditions at 1 AU for the plasma
  were obtained on the base of the measurements of Ly-alpha intensities
  on SOHO/SWAN and interplanetary scintillations data (IPS). In our
  simulation a numerical spatial grid is highly refined along the Voyager
  2 trajectory in order to capture disturbances propagating in the
  solar wind and compare the model with the observations. To validate
  the model and used boundary conditions we compare our results with
  Voyager 2 plasma data. In particular we focus on the time-dependent
  plasma flow in the heliosheath.

---------------------------------------------------------
Title: Dependence of Energetic Ion and Electron Intensities on
Proximity to the Magnetically Sectored Heliosheath: Voyager 1 and
    2 Observations
Authors: Hill, M. E.; Decker, R. B.; Brown, L. E.; Drake, J. F.;
   Hamilton, D. C.; Krimigis, S. M.; Opher, M.
2012AGUFMSH13D..02H    Altcode:
  Taken together, the Voyager 1 and 2 (V1 and V2) spacecraft have
  collected over eleven years of data in the heliosheath. Despite
  extensive study, energetic particles and magnetic fields measured
  in the heliosheath have not been reconciled by existing models. In
  particular the differences between the energetic particle intensity
  variations at V1 and V2 are unexplained. While energetic particle
  intensities at V1 change gradually over seven years in the heliosheath,
  those at V2 vary by a factor ~10 in one year. Energetic particle
  intensities at V2 show temporally coherent variations over a broad
  range of species and energies: from suprathermal ions (10s of keV)
  to galactic cosmic rays (&gt;1 GeV), as well as electrons from 10s of
  keV to &gt;100 MeV, corresponding to a ~4-order-of-magnitude range in
  particle gyroradii. Here we show that many of the intensity variations
  of energetic particle populations in the heliosheath are organized by
  their proximity to two fundamentally different regions—the unipolar
  heliosheath (UHS) and the sectored heliosheath (SHS). The SHS is a
  region of enhanced particle intensities, wherein particle transport,
  acceleration, and magnetic connectivity differ from those in the
  UHS. The SHS may serve as either a reservoir of energetic particles or
  as a region of enhanced transport, depending on the particle species
  and energy. Comparatively, particle intensities in the UHS are greatly
  reduced. We propose that the boundary between the SHS and UHS plays
  as important a role in the physics of heliosheath particles and fields
  as do the termination shock and heliopause.

---------------------------------------------------------
Title: Magnetic reconnection in the heliosheath and the generation
    of anomalous cosmic rays
Authors: Drake, J. F.; Opher, M.; Schoeffler, K. M.; Swisdak, M. M.;
   Dahlin, J.; Fermo, R. L.
2012AGUFMSH13D..03D    Altcode:
  The recent observations of the anomalous cosmic ray (ACR) energy
  spectrum as Voyagers 1 and 2 crossed the heliospheric termination
  shock have called into question the conventional shock source of these
  energetic particles. We suggest that the sectored heliospheric magnetic
  field, which results from the flapping of the heliospheric current
  sheet, compresses across the termination shock and reconnects in the
  subsonic flow of the heliosheath. A number of Voyager observations
  support the hypothesis that the heliosheath sectored field has
  reconnected. Particle-in-cell (PIC) simulations in 2-D suggest that the
  sectors break up into a bath of elongated magnetic islands and that
  most of the magnetic energy released goes into the pickup ions. The
  most energetic ions gain energy as they circulate in contracting and
  merging magnetic islands, a first order Fermi process. The firehose
  condition plays an essential role in the reconnection dynamics and
  particle acceleration. The simulations are being extended to 3-D where
  ions circulating within islands have a finite lifetime. Measured energy
  spectra are similar to those in 2-D. We present a new analytic model
  of particle acceleration in a multi-island reconnecting system that
  describes the energy spectrum of ions parallel and perpendicular to the
  local magnetic field. Including anisotropy is essential to describe
  reconnection driven particle acceleration since Fermi acceleration
  during reconnection drives anisotropy, which is self-consistently
  limited by scattering and the approach to firehose marginal stability,
  which is now explicitly evaluated from the anisotropic spectrum. The
  limiting ACR differential energy spectrum takes the form of a power law
  with a spectral index of 1.5, a result which was obtained earlier in a
  much more primitive model. The new transport equation for the particle
  energy spectrum is suitable for calculating the global distribution
  of reconnection driven energetic particles in the heliosphere.

---------------------------------------------------------
Title: Thermal Pressure of the Proton Plasma in the Inner Heliosheath
Authors: Livadiotis, G.; McComas, D. J.; Schwadron, N. A.; Opher,
   M.; Funsten, H. O.; Fuselier, S. A.; Dayeh, M. A.
2012AGUFMSH11B2207L    Altcode:
  We combine (i) data analysis of IBEX sky maps of ENA fluxes, and
  (ii) modeling of the proton distributions [1] and the plasma flow
  in the inner heliosheath [2], to construct the sky maps of thermal
  observables (e.g., temperature and thermal pressure), and determine
  the thermodynamic processes in the inner heliosheath [3]. Normally,
  multipoint in-situ measurements are needed to determine the
  thermodynamic process of solar wind flow as this evolves in the
  heliosphere. However, because solar wind flow bends within the
  inner heliosheath, its evolution and thermodynamic process can be
  determined using a snapshot map of the whole sky. The first year of
  IBEX data reveal that both the Ribbon and the underlying globally
  distributed flux [4] are characterized by quasi-isobaric processes,
  corresponding to average thermal pressure ~1.1 and ~2.1 pdyn cm-2,
  respectively. While the latter represents the pressure of the inner
  heliosheath, we discuss the physical meaning of the Ribbon's source
  pressure in relationship to a possible ENA secondary source from the
  outer heliosheath. Under the assumptions of the model, we derive
  the total thermal pressure characterizing the entire energy range
  of the source proton distribution that is consistent with a kappa
  distribution. This total thermal pressure is consistent with the
  non-parametric partial pressure, derived directly from the observed ENA
  flux over the finite IBEX energy range. Further application over 3-years
  of IBEX data [5] allows us verify and refine the statistical method
  and to detect temporal variations in derived thermodynamic properties
  of the global heliosheath. (1) Livadiotis, G., et al. 2011, ApJ 734,
  1. (2) Opher, M., et al. 2009, Nature 462, 1036. (3) Livadiotis, G.,
  McComas, D. J. 2012, ApJ 749, 11. (4) Schwadron, N. A., et al. 2011,
  ApJ, 731, 1. (5) McComas, D. J., et al. 2012, ApJSS, In Print.

---------------------------------------------------------
Title: Does a slow magnetosonic bow shock exist in the local
    interstellar medium?
Authors: Zieger, B.; Opher, M.; Schwadron, N. A.; McComas, D. J.;
   Toth, G.
2012AGUFMSH11B2200Z    Altcode:
  The currently accepted best estimates of plasma parameters in the
  local interstellar medium suggest that the speed of the interstellar
  wind (i.e. the relative speed of the local interstellar cloud with
  respect to the Sun) is very slow (i.e., sub-Alfvenic; Opher et al.,
  Science, 2009; Schwadron et al., ApJ, 2011). This means that no fast
  magnetosonic bow shock can be formed in the local interstellar medium
  upstream of the heliosphere, [McComas et al., Science, 2012]. However,
  the existence of a slow magnetosonic bow shock may be possible. With
  current LISM parameters, the Mach number for upstream propagating slow
  magnetosonic waves in the pristine LISM is ~2.1, which suggests that a
  weak quasi-parallel slow bow shock (SBS) in front of our heliopshere
  may exist in some regions. Our new multi-ion, multi-fluid MHD model
  of the heliospheric interface [Prested et al., ApJ, 2012] produces
  such a slow magnetosonic bow shock only in the quasi-parallel region
  where theta_Bn (i.e. the angle between the interstellar magnetic field
  and the normal to the slow magnetosonic surface; SMS) is less than
  45 degrees. The SBS divides the LISM into two distinct regions with
  different plasma populations. One is the pristine LISM and the other
  is the hotter and slower compressed plasma population of the outer
  heliosheath that is spatially restricted to the downstream region of
  the quasi-parallel shock. Slow magnetosonic shocks are generally not
  observed in space plasmas due to their lack of stability. However,
  the plasma in the local interstellar medium exists in a regime not
  commonly observed in interplanetary space. We discuss the possible
  existence of the magnetosonic bow shock in front of the heliosphere,
  the arguments for and against its stability, and its implications for
  heliospheric measurements.

---------------------------------------------------------
Title: Multi-ion, multi-fluid 3-D magnetohydrodynamic simulation of
    the outer heliosphere
Authors: Prested, Christina; Opher, Merav; Toth, Gabor
2012arXiv1211.1908P    Altcode:
  Data from the Voyager probes and the Interstellar Boundary Explorer
  have revealed the importance of pick-up ions (PUIs) in understanding
  the character and behavior of the outer heliosphere, the region of
  interaction between the solar wind and the interstellar medium. In
  the outer heliosphere PUIs carry a large fraction of the thermal
  pressure, which effects the nature of the termination shock, and
  they are a dominate component of pressure in the heliosheath. This
  paper describes the development of a new multi-ion, multi-fluid 3-D
  magnetohydrodynamic model of the outer heliosphere. This model has the
  added capability of tracking the individual fluid properties of multiple
  ion populations. For this initial study two ion populations are modeled:
  the thermal solar wind ions and PUIs produced in the supersonic solar
  wind. The model also includes 4 neutral fluids that interact through
  charge-exchange with the ion fluids. The new multi-ion simulation
  reproduces the significant heating of PUIs at the termination shock,
  as inferred from Voyager observations, and provides properties of PUIs
  in the 3-D heliosheath. The thinning of the heliosheath due to the loss
  of thermal energy in the heliosheath from PUI and neutral interaction is
  also quantified. In future work the multi-ion, multi-fluid model will
  be used to simulate energetic neutral atom (ENA) maps for comparison
  with the Interstellar Boundary Explorer, particularly at PUI energies
  of less than 1 keV.

---------------------------------------------------------
Title: Do Corotating Interaction Region Associated Shocks Survive
    When They Propagate into the Heliosheath?
Authors: Provornikova, E.; Opher, M.; Izmodenov, V.; Toth, G.
2012ApJ...756L..37P    Altcode:
  During the solar minimum at the distance of 42-52 AU from the Sun,
  Voyager 2 observed recurrent sharp, shock-like increases in the
  solar wind speed that look very much like forward shocks (Lazarus
  et al.). The shocks were produced by corotating interaction regions
  (CIRs) that originated near the Sun. After the termination shock
  (TS) crossing in 2007, Voyager 2 entered the heliosheath and
  has been observing the plasma emanated during the recent solar
  minima. Measurements show high variable flow, but there were no
  shocks detected in the heliosheath. When CIR-driven shocks propagate
  to the outer heliosphere, their structure changes due to collision
  and merging processes of CIRs. In this Letter, we explore an effect
  of the merging of CIRs on the structure of CIR-associated shocks. We
  use a three-dimensional MHD model to study the outward propagation of
  the shocks with characteristics similar to those observed by Voyager 2
  at ~45 AU (Lazarus et al. 1999). We show that due to merging of CIRs
  (1) reverse shocks disappear, (2) forward shocks become weaker due
  to interaction with rarefaction regions from preceding CIRs, and (3)
  forward shocks significantly weaken in the heliosheath. Merged CIRs
  produce compression regions in the heliosheath with small fluctuations
  of plasma parameters. Amplitudes of the fluctuations diminish as
  they propagate deeper in the sheath. We conclude that interaction
  of shocks and rarefaction regions could be one of the explanations,
  why shocks produced by CIRs are not observed in the heliosheath by
  Voyager 2 while they were frequently observed upstream the TS.

---------------------------------------------------------
Title: Coronal Heating by Surface Alfvén Wave Damping: Implementation
    in a Global Magnetohydrodynamics Model of the Solar Wind
Authors: Evans, R. M.; Opher, M.; Oran, R.; van der Holst, B.; Sokolov,
   I. V.; Frazin, R.; Gombosi, T. I.; Vásquez, A.
2012ApJ...756..155E    Altcode:
  The heating and acceleration of the solar wind is an active area of
  research. Alfvén waves, because of their ability to accelerate and heat
  the plasma, are a likely candidate in both processes. Many models have
  explored wave dissipation mechanisms which act either in closed or open
  magnetic field regions. In this work, we emphasize the boundary between
  these regions, drawing on observations which indicate unique heating
  is present there. We utilize a new solar corona component of the Space
  Weather Modeling Framework, in which Alfvén wave energy transport is
  self-consistently coupled to the magnetohydrodynamic equations. In
  this solar wind model, the wave pressure gradient accelerates and
  wave dissipation heats the plasma. Kolmogorov-like wave dissipation
  as expressed by Hollweg along open magnetic field lines was presented
  in van der Holst et al. Here, we introduce an additional dissipation
  mechanism: surface Alfvén wave (SAW) damping, which occurs in regions
  with transverse (with respect to the magnetic field) gradients in the
  local Alfvén speed. For solar minimum conditions, we find that SAW
  dissipation is weak in the polar regions (where Hollweg dissipation is
  strong), and strong in subpolar latitudes and the boundaries of open
  and closed magnetic fields (where Hollweg dissipation is weak). We
  show that SAW damping reproduces regions of enhanced temperature at
  the boundaries of open and closed magnetic fields seen in tomographic
  reconstructions in the low corona. Also, we argue that Ulysses data in
  the heliosphere show enhanced temperatures at the boundaries of fast
  and slow solar wind, which is reproduced by SAW dissipation. Therefore,
  the model's temperature distribution shows best agreement with these
  observations when both dissipation mechanisms are considered. Lastly,
  we use observational constraints of shock formation in the low corona to
  assess the Alfvén speed profile in the model. We find that, compared
  to a polytropic solar wind model, the wave-driven model with physical
  dissipation mechanisms presented in this work is more aligned with an
  empirical Alfvén speed profile. Therefore, a wave-driven model which
  includes the effects of SAW damping is a better background to simulate
  coronal-mass-ejection-driven shocks.

---------------------------------------------------------
Title: What did we learn about the 3D Global Structure of the
    Heliosphere with Voyager and IBEX
Authors: Opher, Merav; Provornikova, Elena; Toth, Gabor; Drake, James;
   Swisdak, Marc; Izmodenov, Vladislav
2012cosp...39.1407O    Altcode: 2012cosp.meet.1407O
  In this talk I will review what we have learned in the past couple
  of years about the global structure of the heliosphere. The recent
  measurements in-situ by the Voyager spacecrafts, combined with the
  all-sky images of the heliospheric boundaries by the Interstellar
  Boundary Explorer (IBEX) mission have transformed radically our
  knowledge of the boundaries of the heliosphere. Concepts that resisted
  decades are being revisited due to their puzzling measurements. In
  this talk, I will cover some of these puzzles and what are learning
  regarding the dynamic nature of the heliosphere and heliosheath. When
  uncovering the structure of the heliosheath it is crucial to separate
  spatial from temporal variations. We were fortunate that the extended
  solar minima conditions minimized temporal effects in the heliosphere
  and allowed us to uncover the spatial variations. With the increased
  solar activity becomes a challenge to incorporate temporal effects. I
  will review some of the puzzled observations of by Voyager spacecraft in
  the heliosheath indicating that the presence of the heliospheric current
  sheet might play a crucial role on organizing the heliosheath; affecting
  both the flows and transport of energetic particles. I will review
  as well our attempts to estimate the temporal effects that Corotating
  Interacting Regions have in the heliosheath. Finally, I will address how
  knowledge gained from missions such as Ulysses and future out of the
  ecliptic mission concepts as well as theoretical analysis of physical
  parameters that may be observed from the solar polar orbit will allow
  us a better understanding of the global structure of the heliosphere,
  in particular with its interaction with the interstellar medium.

---------------------------------------------------------
Title: The stellar wind cycles and planetary radio emission of the
    τ Boo system
Authors: Vidotto, A. A.; Fares, R.; Jardine, M.; Donati, J. -F.;
   Opher, M.; Moutou, C.; Catala, C.; Gombosi, T. I.
2012MNRAS.423.3285V    Altcode: 2012arXiv1204.3843V
  τ Boo is an intriguing planet-host star that is believed to undergo
  magnetic cycles similar to the Sun, but with a duration that is about
  one order of magnitude smaller than that of the solar cycle. With the
  use of observationally derived surface magnetic field maps, we simulate
  the magnetic stellar wind of τ Boo by means of three-dimensional
  magnetohydrodynamics numerical simulations. As the properties of
  the stellar wind depend on the particular characteristics of the
  stellar magnetic field, we show that the wind varies during the
  observed epochs of the cycle. Although the mass-loss rates we find
  (∼2.7 × 10<SUP>-12</SUP> M<SUB>⊙</SUB> yr<SUP>-1</SUP>) vary less
  than 3 per cent during the observed epochs of the cycle, our derived
  angular-momentum-loss rates vary from 1.1 to 2.2 × 10<SUP>32</SUP>
  erg. The spin-down times associated with magnetic braking range between
  39 and 78 Gyr. We also compute the emission measure from the (quiescent)
  closed corona and show that it remains approximately constant through
  these epochs at a value of ∼10<SUP>50.6</SUP> cm<SUP>-3</SUP>. This
  suggests that a magnetic cycle of τ Boo may not be detected by X-ray
  observations. We further investigate the interaction between the
  stellar wind and the planet by estimating radio emission from the hot
  Jupiter that orbits at 0.0462 au from τ Boo. By adopting reasonable
  hypotheses, we show that, for a planet with a magnetic field similar
  to Jupiter (∼14 G at the pole), the radio flux is estimated to be
  about 0.5-1 mJy, occurring at a frequency of 34 MHz. If the planet is
  less magnetized (field strengths roughly smaller than 4 G), detection
  of radio emission from the ground is unfeasible due to the Earth's
  ionospheric cut-off. According to our estimates, if the planet is
  more magnetized than that and provided the emission beam crosses the
  observer line-of-sight, detection of radio emission from τ Boo b is
  only possible by ground-based instruments with a noise level of ≲1
  mJy, operating at low frequencies.

---------------------------------------------------------
Title: 3D Global Structure of the Heliosheath with the Sector Region
Authors: Opher, Merav; Toth, Gabor; Drake, James; Swisdak, Marc
2012cosp...39.1406O    Altcode: 2012cosp.meet.1406O
  No abstract at ADS

---------------------------------------------------------
Title: Magnetic reconnection in the heliosheath and its signatures
    and consequences
Authors: Drake, James; Opher, Merav; Swisdak, Marc; Schoeffler, K.
2012cosp...39..479D    Altcode: 2012cosp.meet..479D
  The sectored magnetic field due to the flapping of the heliospheric
  current sheet compresses across the termination shock and may reconnect
  in the heliosheath, driving the anomalous cosmic rays and producing
  a sea of elongated magnetic bubbles. A number of Voyager observations
  are consistent with the bubble picture of the heliosheath, including
  flow enhancements, magnetic field compressions and strongly-altered
  transport properties. We are exploring large-scale structure of the
  the 3-D heliosheath with MHD simulations and the dynamics of magnetic
  reconnection and resultant magnetic bubbles with PIC simulations. The
  goal is to understand particle acceleration and how the resulting
  complex magnetic field will impact the transport of energetic particles,
  including galactic cosmic rays. We find that magnetic bubbles form as
  fully 3-D rather than 2-D objects. Because of the high beta conditions
  of the helioosheath, the characteristic signatures of magnetic
  reconnection differ greatly from that typical of 1AU. Reconnection is
  largely quenched once bubbles reach characteristic widths of the order
  of the sector spacing and the bubble cores bump against the marginal
  firehose condition. The characteristic signatures of bubbles are being
  identified for comparison with the magnetic field data from Voyager.

---------------------------------------------------------
Title: A reconnection mechanism for the generation of anomalous
    cosmic rays
Authors: Drake, James; Opher, Merav; Swisdak, Marc; Schoeffler, K.
2012cosp...39..480D    Altcode: 2012cosp.meet..480D
  The recent observations of the anomalous cosmic ray (ACR) energy
  spectrum as Voyagers 1 and 2 crossed the heliospheric termination
  shock have called into question the conventional shock source of
  these energetic particles. We suggest that the sectored heliospheric
  magnetic field, which results from the flapping of the heliospheric
  current sheet, compresses across the termination shock and reconnects
  in the subsonic flow of the heliosheath. Dropouts in the intensity of
  energetic electrons and the most energetic ACR ions as Voyager 2 exits
  the sector zone support the hypothesis that the heliosheath sectored
  field has reconnected. The sector structure is examined with global MHD
  simultions of the heliosphere. Particle-in-cell (PIC) simulations in
  2-D and 3-D reveal that the sectors break up into a bath of elongated
  magnetic islands and that most of the magnetic energy released goes
  into energetic ions with significant but smaller amounts of energy
  going into electrons. The most energetic particles gain energy as
  they circulate in contracting magnetic islands, a first order Fermi
  process. The simulations also reveal that the firehose condition
  plays an essential role in the reconnection dynamics and particle
  acceleration. An analytic model is constructed in which the Fermi
  drive, modulated by the approach to firehose marginality, is balanced
  by convective loss. The ACR differential energy spectrum takes the
  form of a power law with a spectral index slightly above 1.5. The
  model has the potential to explain several key ACR observations,
  including the similarities in the spectra of different ion species.

---------------------------------------------------------
Title: Reconnection in ICMEs caused by deviations from the Taylor
    state
Authors: Fermo, Raymond Luis; Opher, Merav; Drake, James F.
2012shin.confE..89F    Altcode:
  Recent in situ observations of interplanetary mass ejections (ICMEs)
  found signatures of reconnection exhausts in their interior or
  trailing edge [Gosling et al., 2007]. Whereas reconnection on the
  leading edge of an ICME would indicate an interaction with the
  coronal or interplanetary environment, this result suggests that
  the internal magnetic field reconnects with itself. To this end,
  we propose an approach borrowed from the fusion plasma community. In
  the context of a tokamak, Taylor [1974] showed that the lowest energy
  state corresponds to one in which curl B = λB. Variations from this
  state will result in the magnetic field trying to re-orient itself
  into the Taylor state solution. Because the twist of the flux tube is
  a topological constraint, the means by which this would occur must be
  magnetic reconnection. In tokamaks, the result is a 'sawtooth crash'
  [Kadomtsev, 1975]. In an ICME, if we likewise treat the flux rope as
  a toroidal flux tube, any variation from the Taylor state will result
  in reconnection within the interior of the flux tube, in accord with
  the observation by Gosling et al. [2007]. One such way in which the
  Taylor state might be violated is by the elongation of the flux tube
  cross section in the non-radial direction, as seen in MHD simulations
  of flux tubes propagating through the interplanetary medium. We show
  that this this elongation results in a violation of the Taylor state
  criterion curl B = λB. Lastly, we shall present PIC simulations of
  an elongated flux tube which has deviated from the Taylor state.

---------------------------------------------------------
Title: Modeling of heliosphere and magnetic reconnection in the
    heliosheath
Authors: Opher, Merav; Drake, Jim; Swisdak, Marc; Schoeffller, Kevin;
   Toth, Gabor
2012shin.confE..53O    Altcode:
  The recent measurements in-situ by the Voyager spacecrafts,
  combined with the all-sky images of the heliospheric boundaries by
  the Interstellar Boundary Explorer (IBEX) mission have transformed
  radically our knowledge of the boundaries of the heliosphere. Concepts
  that resisted decades are being revisited due to their puzzling
  measurements. In particular after the crossing of the termination
  shock (TS) by V1 and then by V2, one of the first surprises was that
  both Voyager found no evidence for the acceleration of the anomalous
  cosmic rays at the TS as expected for approximately 25 years. Another
  challenge are the energetically particles intensities that are
  dramatically different at Voyager 1 and 2. In this talk I will review
  the state-of-the art of numerical modeling of the global heliosphere as
  well as our recent model that propose that reconnection is happening in
  the heliosheath within the sector region. All current global models of
  the heliosphere are based on the assumption that the magnetic field in
  the heliosheath is laminar. Recently, we proposed that the annihilation
  of the 'sectored' magnetic field within the heliosheath as it is
  compressed on its approach to the heliopause produces anomalous cosmic
  rays and also energetic electrons. As a product of the annihilation
  of the sectored magnetic field, densely packed magnetic islands (which
  further interact to form magnetic bubbles) are produced. These magnetic
  islands/bubbles will be convected with ambient flows as the sector
  region is carried to higher latitudes filling the heliosheath. As
  a result, the magnetic field in the heliosheath sector region will
  be disordered. I will review results from our three-dimensional MHD
  simulation for the first time included self-consistently the sector
  region and particle-in-cells simulations that followed the kinetic
  evolution of the reconnection of the multiple current sheets. We show
  that due to the high pressure of the interstellar magnetic field
  a north-south asymmetry develops such that the disordered sectored
  region fills a large portion of the northern part of the heliosphere
  with a smaller extension in the southern hemisphere. I will review
  observations that support this scenario indicating that the presence of
  the heliospheric current sheet, where the magnetic field reconnected
  might play a crucial role on organizing the heliosheath; affecting
  both the flows and transport of energetic particles.

---------------------------------------------------------
Title: A Goodbye Gift From AR1476: The First Ground Level Enhancement
    Event of Solar Cycle 24
Authors: Evans, Rebekah Minnel; Zheng, Yihua; Pulkkinen, Antti;
   Taktakishvili, Aleksandre; Mays, M. Leila; Kuznetsova, Maria M.;
   Kozarev, Kamen; Opher, Merav; van der Holst, Bart; Hesse, Michael
2012shin.confE..29E    Altcode:
  We provide an overview of the M-class flare and O-type* coronal
  mass ejection (CME) that occurred on May 17, 2012 as AR1476 was
  passing behind the solar disk. This event is special because the long
  duration flare and well-timed CME produced a solar energetic particle
  (SEP) event that resulted in the first Ground Level Enhancement (GLE)
  of Solar Cycle 24. At the Goddard Space Weather Center, we performed
  real time analysis of the action, and gave a preliminary predicted ICME
  arrival time at NASA"s STEREO-A spacecraft that was within one hour of
  the actual arrival. The CME possibly facilitated the GLE in two ways:
  1) the CME-driven shock could have contributed to the acceleration of
  very high-energy protons required for a GLE, and 2) the CME could have
  disturbed the coronal magnetic field, widening the longitudinal extent
  of the SEP event. This event underscores the need for global modeling
  of CME-driven shocks in the low corona. We discuss CME simulations
  performed with the Space Weather Modeling Framework"s wave-driven
  solar wind model, and emphasize the global structure of the eruption
  as a key to understanding particle acceleration. Comparisons are made
  between this event and the March 7, 2012 X-class flares and R-type*
  CME.*O-type (Occasional), R-type (Rare) on the CME SCORE Scale (see
  http://youtu.be/hN5bChbdky8 for more details). For an overview of the
  event, see the Special Space Weather Report: http://youtu.be/8jutX8JgXIw

---------------------------------------------------------
Title: Magnetic Reconnection and the Kinetic Structure of the
    Heliopause
Authors: Swisdak, Marc; Drake, J. F.; Opher, M.; Schoeffler, K.
2012shin.confE..57S    Altcode:
  At the heliopause magnetic reconnection can potentially occur between
  the heliospheric and interstellar magnetic fields. Complicating this
  picture, however, is the possibility that reconnection has already
  occurred within the heliosheath, between sectors of the heliospheric
  field. We will discuss the implications of this view of heliosheath
  plasma on the expected signatures of reconnection at the heliopause.

---------------------------------------------------------
Title: Sensitivity of ENA emission to various plasma properties in
the outer heliosphere: insight from MHD models
Authors: Prested, Christina Lee; Opher, M.; Toth, G.; Schwadron, N.
2012shin.confE..52P    Altcode:
  Using our new 3D multi-ion, multi-fluid MHD model of the outer
  heliosphere, we probe the nature of energetic neutral atom (ENA)
  emission in the heliosheath. How does ENA emission vary through the
  heliosheath and what properties of the plasma and neutrals is it
  most sensitive to? Where are the majority of ENA's produced and how
  does this insight affect our interpretation of the IBEX all-sky ENA
  maps? From this analysis we begin to answer these questions and engage
  in a dialogue on linking the MHD models of the outer heliosphere with
  the IBEX ENA maps.

---------------------------------------------------------
Title: How does merging of CIRs affect shocks in the outer
    heliosphere?
Authors: Provornikova, Elena; Opher, Merav; Izmodenov, Vlad; Toth,
   Gabor
2012shin.confE..56P    Altcode:
  Observations of the solar wind in the outer heliosphere by Voyager 2
  exhibit many examples of shocks. During the solar minimum in 1994-1997
  near the distance 45 AU from the Sun Voyager 2 observed recurrent
  shocks and shock-like structures that were produced by corotating merged
  interaction regions. Measurements of the heliosheath plasma, emanated
  during the recent solar minima, do not show existence of shocks in the
  heliosheath. We explore an effect of merging of corotating interaction
  regions (CIRs) in the solar wind on the structure of CIR associated
  shocks. Using a 3D MHD model of the solar wind interaction with the
  local interstellar medium, we show that due to interaction of shocks
  and rarefaction waves in a process of merging of CIRs, the shocks
  strongly weaken in the outer heliosphere. Presented study suggests
  that merging process could be one of the explanations why Voyager
  2 did not observe CIR associated shocks in the heliosheath while it
  showed several examples of shocks in the solar wind upstream the TS.

---------------------------------------------------------
Title: Magnetic Drivers of CME Deflection in the Low Corona
Authors: Kay, Christina Danielle; Opher, M.; Evans, R. M.; Gombosi, T.
2012shin.confE..82K    Altcode:
  Coronal mass ejection (CME) observations include cases where CMEs
  follow a trajectory other than the radial path from the associated
  launch site. The presence of a coronal hole can contribute to this
  deflection. Using a 3D MHD model, the Space Weather Modeling Framework,
  we simulate the propagation of a CME near a coronal hole. We establish
  a steady state background solar wind starting with a magnetogram
  of Carrington Rotation 2029 in which the solar wind is driven by
  Alfven waves. Our model includes the effects of surface Alfven wave
  and Kolmogorov-like dissipation. We launch the CME by inserting a
  Titov-Demoulin flux rope in the region corresponding to active region
  0758. Based on the orientation of the CH with respect to the CME, we
  expect deflection to occur mostly in the longitudinal direction. By
  tracking the position of the CME edges in the plane containing the
  Sun's equator we measure a longitudinal deflection of 21 degrees. As
  the deflection occurs low in the corona, a region of low plasma beta,
  we expect magnetic forces to be responsible. We estimate the forces
  from magnetic tension and magnetic pressure gradients and analyze the
  magnitude of these forces over the CME's propagation. We see comparable
  magnitudes between the coronal hole tension force and the difference
  between pressure gradients on opposite sides of the CME. Both forces
  act to push the CME away from the coronal hole. From this we conclude
  both forces should be considered when looking at CME deflection near
  a coronal hole.

---------------------------------------------------------
Title: Near the Boundary of the Heliosphere: A Flow Transition Region
Authors: Opher, M.; Drake, J. F.; Velli, M.; Decker, R. B.; Toth, G.
2012ApJ...751...80O    Altcode:
  Since April of 2010, Voyager 1 has been immersed in a region of near
  zero radial flows, where the solar wind seems to have stopped. The
  existence of this region contradicts current models that predict
  that the radial flows will go to zero only at the heliopause. These
  models, however, do not include the sector region (or include it in
  a kinematic fashion), where the solar magnetic field periodically
  reverses polarity. Here we show that the presence of the sector region
  in the heliosheath, where reconnection occurs, fundamentally alters
  the flows, giving rise to a Flow Transition Region (FTR), where the
  flow abruptly turns and the radial velocity becomes near zero or
  negative. We estimate, based on a simulation, that at the Voyager 1
  location, the thickness of the FTR is around 7-11 AU.

---------------------------------------------------------
Title: Global Numerical Modeling of Energetic Proton Acceleration
    in a CME and Shock in the Solar Corona
Authors: Kozarev, Kamen; Evans, Rebekah M.; Dayeh, Maher A.; Opher,
   Merav; Schwadron, Nathan A.
2012shin.confE..16K    Altcode:
  A growing body of theoretical and observational evidence suggests that
  solar energetic particles may gain most of their energy at traveling
  shocks relatively close to the Sun. The observed and modeled Alfven
  speed profiles in the corona allow for fast shocks to easily develop
  within 20 solar radii. In addition, rapid changes occur in the ejected
  plasma structures and there is a great abundance of charged particles
  close to the Sun compared with interplanetary space. By combining global
  MHD simulation results with a global energetic particle acceleration
  and transport kinetic simulation, we can investigate the effect on a
  seed suprathermal particle population of a coronal mass ejection and
  related shock. We show that the shock and various plasma structures
  may efficiently accelerate suprathermal protons to tens of MeV energies
  between two and eight solar radii for a case study event. Furthermore,
  we show that the resulting SEP flux spectra vary greatly depending on
  the latitudes and longitudes of the guiding field lines. This result
  may provide a single mechanism for the creation of energetic particles
  in the vicinity of the Sun, and thus explain both the impulsive and
  gradual phases of SEP events.

---------------------------------------------------------
Title: Do shocks associated with merged interaction regions in the
    supersonic solar wind survive in the heliosheath?
Authors: Provornikova, E. A.; Opher, M.; Izmodenov, V. V.
2012EGUGA..14.5502P    Altcode:
  Observations of the supersonic solar wind in the outer heliosphere by
  Voyager 2 exhibit many examples of shocks. During the solar minimum,
  shocks are usually associated with global structures in the solar
  wind such as corotating interaction regions. Other transient events
  in the solar wind such as interplanetary CMEs and merged interaction
  regions usually occurred during the maximum of solar activity may
  also drive shocks. As the shocks propagate from the inner to outer
  heliosphere they evolve in the interaction with the ambient solar wind
  and in collision and merging processes among each other. We explore the
  effect of merging of shock pairs in the supersonic solar wind and study
  the propagation of merged shock pairs in the heliosheath. We use a 3D
  MHD model of the solar wind interaction with the interstellar medium
  to generate a couple of shock pairs in the supersonic solar wind with
  characteristics similar to those observed by Voyager 2 at 45 AU from the
  Sun and analyze their propagation into the heliosheath. We show that
  merging of shock pairs do not result in dissipation of shocks; on the
  contrary, in some cases the shocks may become stronger. From modeling
  a propagation of a pair of weak shocks from the region upstream the
  termination shock into the heliosheath we found that several shocks
  may form in the heliosheath. The absence of shocks in the Voyager 2
  plasma data from the heliosheath could indicate that other dissipative
  processes not included in our model are important in the heliosheath.

---------------------------------------------------------
Title: The Heliosheath: The Ultimate Solar System Frontier
Authors: Opher, M.
2012AstRv...7a..68O    Altcode:
  The recent measurements in-situ by the Voyager spacecrafts,
  combined with the all-sky images of the heliospheric boundaries by the
  Interstellar Boundary Explorer (IBEX) mission have transformed radically
  our knowledge of the boundaries of the heliosphere. Concepts that lasted
  decades are being revisited due to their puzzling measurements. In this
  review, I will cover some of these puzzles and what we are learning
  regarding the dynamic nature of the heliosheath.

---------------------------------------------------------
Title: The Heliosheath: The Ultimate Solar System Frontier
Authors: Opher, M.
2012AstRv...7d..68O    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Understanding the Angular Momentum Loss of Low-Mass Stars:
    The Case of V374 Peg
Authors: Vidotto, A. A.; Jardine, M.; Opher, M.; Donati, J. F.;
   Gombosi, T. I.
2011ASPC..448.1293V    Altcode: 2011arXiv1101.1233V; 2011csss...16.1293V
  Recently, surface magnetic field maps had been acquired for a small
  sample of active M dwarfs, showing that fully convective stars (spectral
  types ∼ M4 and later) host intense (∼ kG), mainly axi-symmetrical
  poloidal fields. In particular, the rapidly rotating M dwarf V374 Peg
  (M4), believed to lie near the theoretical full convection threshold,
  presents a stable magnetic topology on a time-scale of ∼ 1 yr. The
  rapid rotation of V374 Peg (P = 0.44 days) along with its intense
  magnetic field point toward a magneto-centrifugally acceleration of
  a coronal wind. In this work, we aim at investigating the structure
  of the coronal magnetic field in the M dwarf V374 Peg by means of
  three-dimensional magnetohydrodynamical (MHD) numerical simulations
  of the coronal wind. For the first time, an observationally derived
  surface magnetic field map is implemented in MHD models of stellar winds
  for a low-mass star. We self-consistently take into consideration the
  interaction of the outflowing wind with the magnetic field and vice
  versa. Hence, from the interplay between magnetic forces and wind
  forces, we are able to determine the configuration of the magnetic
  field and the structure of the coronal winds. Our results enable us
  to evaluate the angular momentum loss of the rapidly rotating M dwarf
  V374 Peg.

---------------------------------------------------------
Title: The dynamics, structure and signatures of magnetic bubbles
    in the outer heliosphere
Authors: Drake, J. F.; Opher, M.; Swisdak, M. M.; Schoeffler, K. M.
2011AGUFMSH13C..07D    Altcode:
  The sectored magnetic field due to the flapping of the heliospheric
  current sheet compresses across the termination shock and may reconnect
  in the heliosheath, driving the anomalous cosmic rays and producing
  a sea of elongated magnetic bubbles. A number of Voyager observations
  are consistent with the bubble picture of the heliosheath, including
  flow enhancements, magnetic field compressions and strongly-altered
  transport properties. We are exploring the 3-D structure and dynamics
  of magnetic bubbles with PIC simulations to understand the associated
  particle acceleration and how the resulting complex magnetic field
  will impact the transport of energetic particles, including galactic
  cosmic rays. We find that magnetic bubbles form as fully 3-D rather than
  2-D objects. In spite of the 3-D nature of the reconnection process,
  particle acceleration does not appear to be significantly changed from
  earlier results in 2-D. The characteristic signatures of magnetic
  bubbles are being identified for comparison with the magnetic field
  data from Voyager. Intriguing Voyager 2 magnetic field observations
  of brief negative polarity excursions during a nominally positive
  unipolar period 2009.6-2010.3 are being studied as possible evidence
  that magnetic bubbles from reconnection in the sector zone are being
  ejected into the nominally unipolar region in a manner analogous to
  spray from a water/air interface.

---------------------------------------------------------
Title: Shocks in the Corona and Inner Heliosphere: Implications for
    Solar Probe and Solar Orbiter
Authors: Korreck, K. E.; Kozarev, K. A.; Evans, R. M.; Opher, M.;
   Schwadron, N. A.; Kasper, J. C.; Case, A. W.
2011AGUFMSH44B..07K    Altcode:
  Shocks in the solar corona and inner heliosphere are thought to be a
  location of acceleration for Solar Energetic Particles (SEPs). Using
  energetic particle transport code, 3-D MHD simulations, in-situ and
  remote imaging data, links between the acceleration and propagation
  of the particles from the Sun out to the Earth can be studied. These
  types of multi-spacecraft and multi-method studies will be key
  to understanding the data from Solar Probe and Solar Orbiter. The
  required observations in terms of science payload of the mission will be
  discussed. In addition, theoretical and modeling work that is necessary
  to better understand the observations will also be highlighted.

---------------------------------------------------------
Title: The Role of Coronal Holes in CME Deflection in the Lower Corona
Authors: Kay, C.; Opher, M.; Evans, R. M.; Gombosi, T. I.
2011AGUFMSH23A1937K    Altcode:
  Coronal mass ejections (CMEs) are known to be deflected when
  ejected near a coronal hole (Gopalswamy et al. 2009). We present
  results from simulations of CMEs near a coronal hole (CH) using a 3D
  magnetohydrodymics model - the Space Weather Modeling Framework. We
  propose magnetic tension and pressure as a cause of the CME deflection
  from the disturbed magnetic field lines of the simulation coronal
  hole. The solar wind is driven via Alfven waves and Kolmogorov-like
  dissipation and surface Alfven wave damping are considered for the
  dissipation of the waves (Evans et al. 2011). The magnetic field at
  the inner boundary is specified with synoptic magnetogram data from
  Carrington Rotation 2029, which corresponds to April 21 to May 18,
  2005. CMEs are generated by inserting an out of equilibrium modified
  Titov-Demoulin flux rope into active region (AR) 0758. Treating the
  CME as a solid body we calculate the expected deflection from the
  coronal hole field lines. We compare this value to the actual path
  of the simulated CMEs for which we define a deflection angle as the
  difference between the observed path and the radial vector connecting
  the center of the Sun and the CME launch site. Finally, we generalize
  the deflection by seeing how it scales with several physical parameters
  such as CME mass, velocity and the separation of the AR and CH as well
  as its intensity. We compare our simulated and estimated values with
  observed deflections (Gopalswamy et. al 2009)

---------------------------------------------------------
Title: 3D MHD modeling of non-stationary flow in the heliosheath
Authors: Provornikova, E.; Opher, M.; Izmodenov, V.; Toth, G.; Oran, R.
2011AGUFMSH11A1910P    Altcode:
  Both Voyager 1 and 2 data show that the heliosheath region is highly
  dynamic. As we climb out of the extended solar minima, time variations
  will be more and more important. The variations in the solar wind
  parameters in the heliosheath can be affected by the propagation of
  different interplanetary disturbances to the outer heliosphere. Using
  a 3D MHD multi-fluid code based on BATS-R-US (Opher et al. 2009),
  with a highly resolved spatial grid in Voyager 2 direction (size of a
  cell 0.48 AU) we study the propagation of the solar wind large-scale
  structures in the heliosheath region. We present our first results on
  the propagation of a forward-reverse shock pair and an abrupt pulse of
  solar wind dynamic pressure in the heliosheath region. We discuss in
  details the structure of the flow in the heliosheath and the response
  of the heliopause to the disturbances. We analyze the intensity of
  variations of the plasma parameters (magnetic field and speed) as
  measured in Voyager 2. We conclude that reflected waves appear in
  the heliosheath and they may contribute to the variations in solar
  wind parameters measured at Voyager spacecrafts. We present as well
  the initial results from a realistic propagation of a global merged
  interaction regions (GMIR) from the Sun to the heliospheric boundaries
  using a new coupled inner heliosphere-to outer heliosphere module.

---------------------------------------------------------
Title: Flow Transition Region in the Heliosheath
Authors: Opher, M.; Drake, J. F.; Velli, M.; Toth, G.
2011AGUFMSH11A1908O    Altcode:
  The tilt between the solar rotation and magnetic axes creates a
  sector region. Recently, we argued that the magnetic field in the
  sector region in the heliosheath has reconnected (Opher et al. 2011)
  and is filled with magnetic structures disconnected from the sun,
  called "bubbles". Here we show, that the sector region affects the
  flows in the heliosheath such as to create a region where the flow
  abruptly turns and the radial flow is near zero or negative. We dub
  this the flow transition region (FTR). The FTR is formed due to several
  effects that we have explored. The sector region in the heliosheath
  defines two flows: the flow within the sector region (region 1)
  behaves like an un-magnetized flow while the flow outside the sector
  (region 2) is connected to the larger heliosphere through the laminar
  magnetic field. The region 1 flow is dominantly affected by the blunt
  heliopause ahead of it and is mostly radial. As the flow streamlines
  approach the heliopause they turn abruptly, creating the FTR.This
  region didn't exist in previous simulations with no sectors where the
  flows downstream of the termination shock turn almost immediately to
  the sides and to higher latitudes. The thickness of FTR varies and is
  thinner in the southern hemisphere. We estimate, based on a recent 3D
  MHD simulation (Opher et al. 2011) that at the Voyager 1 location the
  thickness of FTR is 10-12AU. The simulations accurately reproduce the
  Voyager 1 flows. Since 2010 Voyager 1 has been immersed in the FTR,
  based on the negligible flows detected (Krimigis et al. 2011). If no
  other temporal dependent effects change the overall structure of the
  heliosphere, Voyager 1 is expected to cross the heliopause in the
  next 3-5 years. The FTR is much narrower in the southern hemisphere
  and Voyager 2 is expected to enter that region in the next couple years.

---------------------------------------------------------
Title: Damping of Surface Alfvén Waves in a 3D Simulation of
    Stellar Winds
Authors: Evans, R. M.; Opher, M.; Jatenco-Pereira, V.; Gombosi, T. I.
2011ASPC..448.1151E    Altcode: 2011csss...16.1151E
  Surfave Alfvén wave damping has been used by many authors in order
  to provide an heating and acceleration mechanism for driving winds
  in many regions of HR diagram. Based on the 1D solar wind model
  of Jatenco-Pereíra et al. (1994) we investigate the effect of
  surface Alfvén wave damping, for solar minima conditions, using a
  three-dimensional (3D) magnetohydrodynamics (MHD) model. The surface
  Alfvén wave damping length LSW depends on the superradial expansion
  factor S of magnetic field lines. We quantify S for Carrington Rotation
  1912 with a steady state solar background generated with the Space
  Weather Modeling Framework, and compare with estimates by Dobrzycka et
  al. (1999) using SOHO observations. We estimate the surface Alfvén
  wave damping for active regions, quiet sun, and the border between
  open and closed magnetic field lines (Evans et al. 2009).

---------------------------------------------------------
Title: The heliospheric structure during the recent solar minimum:
    shocks in the lower corona and the magnetic field structure in
    the heliosheath
Authors: Opher, M.; Drake, J. F.; Evans, R.; Provornikova, E.; Swisdak,
   M. M.; Schoeffler, K. M.; van der Holst, B.; Toth, G.
2011AGUFMSH23D..06O    Altcode:
  In this talk we review the recent heliospheric structure as
  affected by the recent solar minimum. We will focus especially on
  two frontiers areas: a) evolution of shocks in the lower corona and
  b) the heliosheath. In particular, we will focus on how the recent
  extended minimum allowed us to separate spatial and temporal effects
  in the outer heliosphere. We will describe new phenomena that we were
  able to explore, the reconnection of the sectored magnetic field in the
  heliosheath. Very little is known on how shocks thought to be driven by
  CMEs, form and evolve in the lower corona. This is a crucial area since
  its has been shown by observations that they form low in the corona
  (1-4Rs) and coincide with the acceleration to GeV energies. We will
  describe our recent attempts (e.g., Evans et al. 2011; Das et al.;
  2011) to uncover the evolution of CMEs at these locations. All the
  current global models of the heliosphere are based on the assumption
  that the magnetic field in the heliosheath, in the region close to
  the heliopause is laminar and connect back to the Sun. We argue
  recently, based on Voyager observations that in that region the
  heliospheric magnetic field is not laminar but instead consists of
  magnetic bubbles, or magnetic structures disconnected from the Sun
  (Opher et al. 2011). The consequence is that the heliopause might
  be a porous membrane instead of a shield. As the sun increased its
  activity, it will be more complicated to disentangle temporal from
  spatial and global structure. We will comment on how the increased
  solar activity might affect the sector structure in the heliosheath as
  well as the implication for our understanding of how galactic cosmic
  rays enter the heliosphere. Due to the slow flows in the heliosheath,
  the heliosheath has a long time memory of solar activity. Moreover,
  Corotating Interaction Regions and Global Merged Interacting Regions
  are known to disturb the termination shock and heliopause as well
  as the heliosheath flows and fields. For example it is still poorly
  understood how temporal effects propagate in the heliosheath and affect
  the level of turbulence. We will present some of our recent work trying
  to understand how temporal effects, such as CIRs propagates from the
  sun into the outer heliosphere.

---------------------------------------------------------
Title: Variation of Pick-up Ion Pressure throughout the Heliosheath:
    3-Dimensional Multi-ion, Multi-fluid Magnetohydrodynamic Simulation
    of the Outer Heliosphere
Authors: Prested, C. L.; Opher, M.; Toth, G.; Schwadron, N. A.
2011AGUFMSH21C..07P    Altcode:
  The interaction between the solar system and interstellar medium (ISM)
  involves multiple populations of ions and neutrals of both heliosphere
  and local interstellar origin. Of special interest is the pick-up ion
  population generated in the inner heliosphere, as it carries upwards of
  80% the plasma pressure in the outer heliosphere [Richardson et al.,
  2008]. The Interstellar Boundary Explorer (IBEX) global energetic
  neutral atom (ENA) maps of the interstellar-heliosphere interaction
  show temporal variation in the interaction region upwards of 15% in ENA
  emission over a time scale of &lt; 6 months. The short time scale and
  magnitude of the variation implies that the origin of this variation
  comes from the solar system plasma, which has considerable solar
  cycle variation, and likely not from variability in the interstellar
  medium. The dynamic properties of the pressure dominant pick-up ions
  are a likely candidate for this temporal variation. We ask, how does
  the pick-up ion pressure vary through the heliosheath, spatially
  and temporally? In previous 3-dimensional magnetohydrodynamic (MHD)
  simulations of the outer heliosphere, a single plasma fluid was used
  to describe the behavior of the solar wind plasma and the pick-up
  ions. For simulating ENA maps, the single plasma fluid was assumed
  to have a kappa distribution, describing the thermal core of solar
  wind plasma and the suprathermal tail of pick-up ions [Prested et
  al., 2008]. These simulations captured the global structure of the
  heliosphere but lost information on how the pick-up ion population and
  the pressure it carries evolve through the ISM-heliosphere interaction
  region. This information is vital for understanding the energy-dependent
  temporal and spatial variations observed in the IBEX global maps. We
  have extended our previous 3-d MHD multifluid model [Opher et al., 2009]
  to include the solar wind and pick-up ions as 2 separate ion fluids
  [i.e. Glocer et al., 2009 ], in addition to treating 4 separate neutral
  populations. Additionally, we introduce temporal variation by simulating
  the global heliosphere with solar-minimum and solar-maximum solar wind
  conditions. We quantify how the pick-up ion pressure varies through the
  heliosheath under these conditions and validate our results through
  comparison with the Voyager 1 and 2 heliosheath measurements. From
  our analysis of the two extreme solar wind cases, we conclude whether
  or not variation in pick-up ion pressure could be responsible for the
  6-month, large scale variation seen in the IBEX global maps.

---------------------------------------------------------
Title: CME-Sheath and Shock Heating by Surface Alfven Wave Dissipation
    in the Lower Corona
Authors: Evans, R.; Opher, M.; van der Holst, B.
2011AGUFMSH43A1933E    Altcode:
  We use the new solar corona component of the Space Weather Modeling
  Framework (van der Holst et al. 2010), in which the Alfven wave energy
  evolution is coupled self-consistently to the magnetohydrodynamic
  equations, to study the evolution of a coronal mass ejection (CME)
  and the shock it drives in the lower corona (2-8Rs). In this solar
  wind model, the wave pressure gradient accelerates the wind, and wave
  dissipation heats the wind. Kolmogorov-like dissipation and surface
  Alfven wave damping are considered for the dissipation of the waves
  (Evans et al. 2011). We use a modified Titov-Demoulin flux rope to
  initiate an eruption, and include magnetogram data from CR2029 (May
  2005) as a boundary condition for the coronal magnetic field. Synthetic
  white light images from the simulation are used to determine the
  lateral expansion. We show that the expansion of the flux rope leads
  to the concentration of wave energy at the shock and in the sheath
  region. The expansion also creates a piled-up compression (PUC) region
  of plasma density at the back of the sheath, strongest at the flanks
  of the CME. The wave energy concentrated at the shock and sheath is
  dissipated by surface Alfven wave damping due to the density gradients,
  which heats the sheath. We present analysis of the momentum exchange
  between the solar wind and the waves, and discuss the effect of wave
  dissipation on the CME evolution.

---------------------------------------------------------
Title: Reconnection at the Heliopause and the Motion of Energetic
    Particles in the Outer Heliosphere
Authors: Swisdak, M. M.; Drake, J. F.; Opher, M.; Knizhnik, K.
2011AGUFMSH11B1924S    Altcode:
  At the heliopause the uni-directional interstellar magnetic field
  abuts the piled-up sectored magnetic field and multiple current
  sheets of the heliosheath. Reconnection of these fields provides a
  natural pathway for energetic particles (e.g., anomalous cosmic rays
  produced in the heliosphere and galactic cosmic rays produced outside)
  to move across the heliopause. Here we report on 2D particle-in-cell
  simulations of this system that self-consistently include a small
  number of energetic particles designed to mimic these energetic
  particles. Reconnection occurs at multiple current layers within the
  heliosheath and leads to the formation of a bath of magnetic bubbles. By
  tracing the trajectories of energetic particles through this bath we
  show that their propagation acquires some characteristics of a random
  walk. We discuss the implications for this behavior on the detection
  and propagation of energetic particles throughout the outer heliosphere.

---------------------------------------------------------
Title: Seemingly Incongruous Voyager 1 &amp; 2 Energetic Particle
    Observations in the Heliosheath Through 2011
Authors: Hill, M. E.; Decker, R. B.; Drake, J. F.; Hamilton, D. C.;
   Krimigis, S. M.; Opher, M.; Roelof, E. C.
2011AGUFMSH11A1906H    Altcode:
  Conditions are changing in the heliosheath at the positions of Voyager
  1 (V1) and Voyager 2 (V2) and are doing so in unexpected ways that
  so far defy a single consistent interpretation. Some characteristic
  intensity variations cut across a surprisingly broad range of energies
  and species, from termination shock particles (TSPs), to energetic
  electrons, to light and heavy anomalous cosmic rays (ACRs), and to
  galactic cosmic rays (GCRs). The changes must be a mix of spatial
  structure and temporal changes produced by the rise in activity of
  Solar Cycle 24 in January 2010. Yet there are drastic differences
  between some of the same species at V1 compared with V2. The puzzling
  observations include V1 ACR intensities beginning to decline while at V2
  they are exponentially increasing, finally reaching levels comparable
  to or even exceeding those at V1. A distinct pattern of increases and
  decreases is seen at V2 in TSPs, electrons, light ACRs, and GCRs, but
  not in ACR heavy ions. However some things are happening similarly at
  V1 and V2, like a recent increase in GCR protons. We will present an
  overview of these observations, which also include spectral properties,
  anisotropies, and solar wind speed. An essential interpretive element
  is possible differences in the heliosheath configuration, in particular
  the location of the sector region between V1 and V2 and the proximity
  to the heliopause.

---------------------------------------------------------
Title: 3D Simulations of Tilted Magnetospheres of Weak-Lined T
    Tauri Stars
Authors: Vidotto, A. A.; Opher, M.; Jatenco-Pereira, V.; Gombosi, T. I.
2011RMxAC..40..133V    Altcode:
  We perform 3D time-dependent numerical MHD simulations of the wind
  and magnetospheric structures of weak-lined T Tauri stars, in the case
  there is a misalignment between the axis of rotation of the star and
  its magnetic dipole moment vector. The model allow us to study the
  interaction of a magnetized wind with a magnetized exoplanet. Such
  interaction gives rise to reconnection, generating electrons that
  propagate along the planet's magnetic field lines and produce electron
  cyclotron radiation at radio wavelengths. This radio emission could
  be detectable by LOFAR in the near future.

---------------------------------------------------------
Title: Ensemble-averaged heliosheath proton spectra
Authors: Prested, Christina Lee; Schwadron, N.; Fuselier,
   H. O. Funsten. A.; Janzen, P. H.; McComas, D. J.; Opher, M.;
   Reisenfeld, D. B.
2011shin.confE..64P    Altcode:
  New in situ observations by Voyager 2 and and remote observations
  by the Interstellar Boundary Explorer (IBEX) have provided the first
  measurements of the heliosheath plasma energy distribution. Contained
  within this energy distribution is the physics of the termination
  shock and the subsequent heating of the heliosheath plasma. The
  Voyager measurements provide a time series of the plasma at a local
  point, while the IBEX observations provide a global look at the
  line-of-sight averaged plasma, an ensemble-average of the spatially and
  temporally varying plasma in a given direction. To unravel the global
  information contained in the IBEX energy spectra, we must understand
  how ensemble-averaging effects the observed energy spectra. We take
  advantage of overlap between the Voyager and IBEX data sets and
  explore the average energy spectra produced by physically motivated
  time and spatial distributions of heliosheath plasma. Other aspects
  of the heliosheath energy distribution, particularly the pick-up ions,
  are also considered.

---------------------------------------------------------
Title: Interaction of a CME-driven Shock and Sheath with an Alfven
    Wave-driven Solar Wind in the Lower Corona
Authors: Evans, Rebekah Minnel; Opher, Merav; Gombosi, Tamas I.
2011shin.confE.141E    Altcode:
  Coronal Mass Ejections (CMEs) are driven by a release of magnetic
  energy, which dominates the interaction between the CME and the solar
  wind in the very low corona (at heights less than 2 solar radii). At
  distances larger than 10 solar radii, the interaction between the
  solar wind and a CME is controlled by the drag force. In this work,
  we study the interaction of a CME with a solar wind driven by Alfven
  waves in the lower corona (2-7 solar radii). We use the new solar
  corona component of the Space Weather Modeling Framework (van der Holst
  et al. 2010), in which the Alfven wave energy evolution is coupled
  self-consistently to the MHD equations. The wave stress accelerates the
  wind, and wave dissipation heats the wind. The wave dissipation is due
  to turbulence and to surface Alfven wave damping. We use a modified
  Titov-Demoulin flux rope to initiate the eruption, and include MDI
  magnetogram data from CR2029 (May 2005) as a boundary condition for
  the coronal magnetic field. Synthetic white light images from the
  simulation are used to determine the lateral expansion from both halo
  and limb event vantage points. We show that the expansion of the flux
  rope leads to the concentration of wave energy at the shock and in
  the sheath region. The expansion also creates a piled-up compression
  (PUC) region of plasma density at the back of the sheath, strongest
  at the flanks of the CME. The wave energy concentrated at the shock
  and sheath is dissipated by surface Alfven wave damping due to the
  density gradients, which heats the sheath. We present analysis of the
  momentum exchange between the solar wind and the waves, and the effect
  of wave dissipation on the CME evolution.

---------------------------------------------------------
Title: 3D MHD modeling of the CMIR propagation in the heliosheath
Authors: Provornikova, Elena; Opher, M.; Izmodenov, V.; Gabor, T.
2011shin.confE..69P    Altcode:
  One of the dominating large-scale structures in the solar wind is
  an interaction region (or corotating interaction region CIR). As the
  CIRs propagate outward they merge each other and form CMIRs. CMIRs were
  clearly observed by Voyager 1 and 2 at large heliospheric distances. We
  use global 3D time-dependent MHD multi-fluid model (Opher et al. 2009)
  of the interaction of the solar wind with the local interstellar medium
  to study the evolution of the CMIR from 30 AU to the heliospheric
  boundaries. We show the change in CMIR structure caused by the
  interaction with the heliospheric termination shock and study the
  propagation of the modified CMIR in the heliosheath. We discuss the
  response of the heliopause to the CMIR structure and the following
  flow in the heliosheath.

---------------------------------------------------------
Title: Simulation of a CME Near a Coronal Hole
Authors: Kay, Christina Danielle; Opher, M.; Evans, R.; Gombosi, T.
2011shin.confE.132K    Altcode:
  We present results from the simulation of a coronal mass ejection
  (CME) near a large coronal hole. Observational evidence suggests that
  the open field lines from a coronal hole can deflect a CME from its
  initial trajectory. Using the Space Weather Modeling Framework with a
  background solar wind driven by Alfven waves that includes the effects
  of surface Alfven wave dissipation, a CME is launched from active
  region 0758 in Carrington rotation 2029. We follow the propagation
  from the lower corona out to approximately 4.5 solar radii. We find
  that the presence of the CME induces curvature in the open field lines
  of the coronal hole and investigate the resulting magnetic tension as
  a possible cause of CME deflection. We also explore the effect of the
  open field lines on the shape of the CME.

---------------------------------------------------------
Title: Is the Magnetic Field in the Heliosheath Laminar or a Turbulent
    Sea of Bubbles?
Authors: Opher, M.; Drake, J. F.; Swisdak, M.; Schoeffler, K. M.;
   Richardson, J. D.; Decker, R. B.; Toth, G.
2011ApJ...734...71O    Altcode: 2011arXiv1103.2236O
  All current global models of the heliosphere are based on the assumption
  that the magnetic field in the heliosheath, in the region close to
  the heliopause (HP), is laminar. We argue that in that region the
  heliospheric magnetic field is not laminar but instead consists of
  magnetic bubbles. We refer to it as the bubble-dominated heliosheath
  region. Recently, we proposed that the annihilation of the "sectored"
  magnetic field within the heliosheath as it is compressed on its
  approach to the HP produces anomalous cosmic rays and also energetic
  electrons. As a product of the annihilation of the sectored magnetic
  field, densely packed magnetic islands (which further interact to form
  magnetic bubbles) are produced. These magnetic islands/bubbles will be
  convected with ambient flows as the sector region is carried to higher
  latitudes filling the heliosheath. We further argue that the magnetic
  islands/bubbles will develop upstream within the heliosheath. As a
  result, the magnetic field in the heliosheath sector region will be
  disordered well upstream of the HP. We present a three-dimensional
  MHD simulation with very high numerical resolution that captures the
  north-south boundaries of the sector region. We show that due to the
  high pressure of the interstellar magnetic field a north-south asymmetry
  develops such that the disordered sectored region fills a large portion
  of the northern part of the heliosphere with a smaller extension in the
  southern hemisphere. We suggest that this scenario is supported by the
  following changes that occurred around 2008 and from 2009.16 onward: (1)
  the sudden decrease in the intensity of low energy electrons (0.02-1.5
  MeV) detected by Voyager 2, (2) a sharp reduction in the intensity of
  fluctuations of the radial flow, and (3) the dramatic differences in
  intensity trends between galactic cosmic ray electrons (3.8-59 MeV) at
  Voyager 1 and 2. We argue that these observations are a consequence of
  Voyager 2 leaving the sector region of disordered field during these
  periods and crossing into a region of unipolar laminar field.

---------------------------------------------------------
Title: Kinetic versus Multi-fluid Approach for Interstellar Neutrals
in the Heliosphere: Exploration of the Interstellar Magnetic Field
    Effects
Authors: Alouani-Bibi, Fathallah; Opher, Merav; Alexashov, Dimitry;
   Izmodenov, Vladislav; Toth, Gabor
2011ApJ...734...45A    Altcode: 2011arXiv1103.3202A
  We present a new three-dimensional (3D) self-consistent two-component
  (plasma and neutral hydrogen) model of the solar wind interaction with
  the local interstellar medium (LISM). This model (K-MHD) combines
  the magnetohydrodynamic treatment of the solar wind and the ionized
  LISM component with a kinetic model of neutral interstellar hydrogen
  (LISH). The local interstellar magnetic field (B <SUB>LISM</SUB>)
  intensity and orientation are chosen based on an early analysis of the
  heliosheath flows. The properties of the plasma and neutrals obtained
  using the K-MHD model are compared to previous multi-fluid and kinetic
  models. The new treatment of LISH revealed important changes in the
  heliospheric properties not captured by the multi-fluid model. These
  include a decrease in the heliocentric distance to the termination
  shock (TS), a thinner heliosheath, and a reduced deflection angle (θ)
  of the heliosheath flows. The asymmetry of the TS, however, seems to
  be unchanged by the kinetic aspect of the LISH.

---------------------------------------------------------
Title: Signatures of two distinct driving mechanisms in the evolution
    of coronal mass ejections in the lower corona
Authors: Loesch, C.; Opher, M.; Alves, M. V.; Evans, R. M.; Manchester,
   W. B.
2011JGRA..116.4106L    Altcode:
  We present a comparison between two simulations of coronal mass
  ejections (CMEs), in the lower corona, driven by different flux rope
  mechanisms presented in the literature. Both mechanisms represent
  different magnetic field configurations regarding the amount of twist
  of the magnetic field lines and different initial energies. They are
  used as a “proof of concept” to explore how different initialization
  mechanisms can be distinguished from each other in the lower corona. The
  simulations are performed using the Space Weather Modeling Framework
  (SWMF) during solar minimum conditions with a steady state solar
  wind obtained through an empirical approach to mimic the physical
  processes driving the solar wind. Although the two CMEs possess
  different initial energies (differing by an order of magnitude) and
  magnetic configurations, the main observables such as acceleration,
  shock speed, Mach number, and $\theta$<SUB>Bn</SUB> (the angle between
  the shock normal and the upstream magnetic field) present very similar
  behavior between 2 and 6 R<SUB>$\odot$</SUB>. We believe that through
  the analysis of other quantities, such as sheath width and postshock
  compression (pileup and shock indentation compressions), the effect
  of different magnetic configurations and initializations can be
  distinguished. We discuss that coronal models that employ a reduced
  value of polytropic index (γ) may significantly change the energetics
  of the CME and that the background solar wind plays an important role
  in the CMEs' shock and sheath evolution.

---------------------------------------------------------
Title: Downstream structure and evolution of a simulated CME-driven
    sheath in the solar corona
Authors: Liu, Y. C. -M.; Opher, M.; Wang, Y.; Gombosi, T. I.
2011A&A...527A..46L    Altcode:
  Context. The transition of the magnetic field from the ambient magnetic
  field to the ejecta in the sheath downstream of a coronal mass ejection
  (CME) driven shock is analyzed in detail. The field rotation in the
  sheath occurs in a two-layer structure. In the first layer, layer 1,
  the magnetic field rotates in the coplanarity plane (plane of shock
  normal and the upstream magnetic field), and in layer 2 rotates off
  this plane. We investigate the evolution of the two layers as the
  sheath evolves away from the Sun. <BR /> Aims: In situ observations
  have shown that the magnetic field in the sheath region in front of
  an interplanetary coronal mass ejection (ICME) form a planar magnetic
  structure, and the magnetic field lines drape around the flux tube. Our
  objective is to investigate the magnetic configuration of the CME near
  the sun. <BR /> Methods: We used the space weather modeling framework
  (SWMF), a 3D magnetohydrodynamics (MHD) simulation code, to simulate
  the propagation of CMEs and the shock driven by it. <BR /> Results: We
  find that close to the Sun, layer 2 dominates the width of the sheath,
  diminishing its importance as the sheath evolves away from the Sun,
  in agreement with observations at 1 AU.

---------------------------------------------------------
Title: Evolution of Piled-up Compressions in Modeled Coronal Mass
    Ejection Sheaths and the Resulting Sheath Structures
Authors: Das, Indrajit; Opher, Merav; Evans, Rebekah; Loesch,
   Cristiane; Gombosi, Tamas I.
2011ApJ...729..112D    Altcode:
  We study coronal mass ejection (CME)-driven shocks and the resulting
  post-shock structures in the lower corona (2-7 R <SUB>sun</SUB>). Two
  CMEs are erupted by modified Titov-Démoulin (TD) and Gibson-Low (GL)
  type flux ropes (FRs) with the Space Weather Modeling Framework. We
  observe a substantial pile-up of density compression and a narrow region
  of plasma depletion layer (PDL) in the simulations. As the CME/FR
  moves and expands in the solar wind medium, it pushes the magnetized
  material lying ahead of it. Hence, the magnetic field lines draping
  around the CME front are compressed in the sheath just ahead of the
  CME. These compressed field lines squeeze out the plasma sideways,
  forming PDL in the region. Solar plasma being pushed and displaced from
  behind forms a strong piled-up compression (PUC) of density downstream
  of the PDL. Both CMEs have comparable propagation speeds, while GL
  has larger expansion speed than TD due to its higher initial magnetic
  pressure. We argue that high CME expansion speed along with high solar
  wind density in the region is responsible for the large PUC found in
  the lower corona. In case of GL, the PUC is much wider, although the
  density compression ratio for both the cases is comparable. Although
  these simulations artificially initiate out-of-equilibrium CMEs and
  drive them in an artificial solar wind solution, we predict that PUCs,
  in general, will be large in the lower corona. This should affect the
  ion profiles of the accelerated solar energetic particles.

---------------------------------------------------------
Title: Powerful winds from low-mass stars: V374 Peg
Authors: Vidotto, A. A.; Jardine, M.; Opher, M.; Donati, J. F.;
   Gombosi, T. I.
2011MNRAS.412..351V    Altcode: 2010MNRAS.tmp.1873V; 2010arXiv1010.4762V
  The M dwarf V374 Peg (M4) is believed to lie near the theoretical
  mass threshold for fully convective interiors. Its rapid rotation
  (P= 0.44 d) along with its intense magnetic field point towards
  magnetocentrifugal acceleration of a coronal wind. In this work, we
  investigate the structure of the coronal wind of V374 Peg by means of
  three-dimensional magnetohydrodynamical (MHD) numerical simulations. For
  the first time, an observationally derived surface magnetic field
  map is implemented in MHD models of stellar winds for a low-mass
  star. By self-consistently taking into consideration the interaction
  of the outflowing wind with the magnetic field and vice versa, we
  show that the wind of V374 Peg deviates greatly from a low-velocity,
  low-mass-loss rate solar-type wind. We have found general scaling
  relations for the terminal velocities, mass-loss rates and spin-down
  times of highly magnetized M dwarfs. In particular, for V374 Peg, our
  models show that terminal velocities across a range of stellar latitudes
  reach u<SUB>∞</SUB>≃ (1500-2300) n<SUP>-1/2</SUP><SUB>12</SUB>
  km s<SUP>-1</SUP>, where n<SUB>12</SUB> is the coronal wind base
  density in units of 10<SUP>12</SUP> cm<SUP>-3</SUP>, while the
  mass-loss rates are about ?. We also evaluate the angular momentum
  loss of V374 Peg, which presents a rotational braking time-scale τ≃
  28 n<SUP>-1/2</SUP><SUB>12</SUB> Myr. Compared to observationally
  derived values from period distributions of stars in open clusters,
  this suggests that V374 Peg may have low coronal base densities
  (≲10<SUP>11</SUP> cm<SUP>-3</SUP>). We show that the wind ram pressure
  of V374 Peg is about 5 orders of magnitude larger than for the solar
  wind. Nevertheless, a small planetary magnetic field intensity (∼0.1
  G) is able to shield a planet orbiting at 1 au against the erosive
  effects of the stellar wind. However, planets orbiting inside the
  habitable zone of V374 Peg, where the wind ram pressure is higher, might
  be facing a more significant atmospheric erosion. In that case, higher
  planetary magnetic fields of, at least, about half the magnetic field
  intensity of Jupiter are required to protect the planet's atmosphere.

---------------------------------------------------------
Title: Learning from the Outer Heliosphere: Interplanetary Coronal
    Mass Ejection Sheath Flows and the Ejecta Orientation in the Lower
    Corona
Authors: Evans, R. M.; Opher, M.; Gombosi, T. I.
2011ApJ...728...41E    Altcode:
  The magnetic field structure of the ejecta of a coronal mass ejection
  (CME) is not known well near the Sun. Here we demonstrate, with a
  numerical simulation, a relationship between the subsonic plasma flows
  in the CME-sheath and the ejecta magnetic field direction. We draw an
  analogy to the outer heliosphere, where Opher et al. used Voyager 2
  measurements of the solar wind in the heliosheath to constrain the
  strength and direction of the local interstellar magnetic field. We
  simulate three ejections with the same initial free energy,
  but different ejecta magnetic field orientations in relation to
  the global coronal field. Each ejection is launched into the same
  background solar wind using the Space Weather Modeling Framework. The
  different ejecta magnetic field orientations cause the CME-pause (the
  location of pressure balance between solar wind and ejecta material)
  to evolve differently in the lower corona. As a result, the CME-sheath
  flow deflections around the CME-pauses are different. To characterize
  this non-radial deflection, we use θ_F=tan ^{-1}{V_N}/{V_T}, where
  V<SUB>N</SUB> and V<SUB>T</SUB> are the normal and tangential plasma
  flow as measured in a spacecraft-centered coordinate system. Near the
  CME-pause, we found that θ<SUB> F </SUB> is very sensitive to the
  ejecta magnetic field, varying from 45° to 98° between the cases when
  the CME-driven shock is located at 4.5 R <SUB>sun</SUB>. The deflection
  angle for each case is found to evolve due to rotation of the ejecta
  magnetic field. We find that this rotation should slow or stop by 10 R
  <SUB>sun</SUB> (also suggested by observational studies). These results
  indicate that an observational study of CME-sheath flow deflection
  angles from several events (to account for the interaction with the
  solar wind), combined with numerical simulations (to estimate the
  ejecta magnetic field rotation between eruption and 10 R <SUB>sun</SUB>)
  can be used to constrain the ejecta magnetic field in the lower corona.

---------------------------------------------------------
Title: Energetic protons accelerated by a model Coronal Mass Ejection
    and associated shock in the solar corona
Authors: Kozarev, K. A.; Evans, R. M.; Dayeh, M. A.; Schwadron, N. A.;
   Opher, M.; Korreck, K. E.; Gombosi, T. I.
2010AGUFMSH33A1832K    Altcode:
  Modeling and observational studies of coronal and interplanetary
  shocks suggest that they are most effective in accelerating Solar
  Energetic Particles (SEP) relatively close to the Sun. Interplanetary
  shocks have been quite well studied, thanks to in situ measurements
  of energetic articles near Earth and throughout the solar system. Many
  bursts of energetic charged particles observed close to Earth are not
  directly associated with shocks that pass by Earth. This suggests
  that energetic particles could be accelerated much lower, in the
  solar corona, possibly by shocks that form near the Sun or through
  magnetic reconnection. For the first time, we have used results
  from a three-dimensional time-dependent magnetohydrodynamic (MHD)
  simulation of a coronal mass ejection (CME) in the solar corona,
  coupled with a three-dimensional energetic particle propagation
  and acceleration model, in order to investigate how suprathermal
  protons respond to an enhanced traveling plasma structure and shock
  in the corona. The detailed MHD simulation reveals multiple density
  and magnetic field enhancements behind the traveling shock, which
  cause rapid acceleration of suprathermal protons via diffusive shock
  acceleration in the kinetic simulation. The resulting spectra and time
  profiles of energetic protons at different radial distances from the
  Sun are presented. This work will help address the question of whether
  and how efficient CMEs and shocks close to the Sun are in accelerating
  suprathermal particle populations to high energies.

---------------------------------------------------------
Title: Is the Magnetic Field in the Heliosheath Sector Region and
    in the Outer Heliosheath Laminar?
Authors: Opher, M.; Drake, J. F.; Swisdak, M. M.; Toth, G.
2010AGUFMSH23D..04O    Altcode:
  All the current global models of the heliosphere are based on the
  assumption that the magnetic field in the outer heliosheath close to
  the heliopause is laminar. We argue that in the outer heliosheath the
  heliospheric magnetic field is not laminar but instead consists of
  nested magnetic islands. Recently, we proposed (Drake et al. 2009)
  that the annihilation of the “sectored” magnetic field within the
  heliosheath as it is compressed on its approach to the heliopause
  produces the anomalous cosmic rays (ACRs) and also energetic
  electrons. As a product of the annihilation of the sectored magnetic
  field, densly-packed magnetic islands are produced. These magnetic
  islands will be convected with the ambient flows as the sector boundary
  is carried to higher latitudes filling the outer heliosheath. We
  further argue that the magnetic islands will develop upstream (but
  still within the heliosheath) where collisionless reconnection is
  unfavorable -- large perturbations of the sector structure near the
  heliopause will cause compressions of the current sheet upstream,
  triggering reconnection. As a result, the magnetic field in the
  heliosheath sector region will be disordered well upstream of the
  heliopause. We present a 3D MHD simulation with unprecedent numerical
  resolution that captures the sector boundary. We show that due to
  the high pressure of the interstellar magnetic field the disordered
  sectored region fills a large portion of the northern part of the
  heliosphere with a smaller extension in the southern hemisphere. We
  test these ideas with observations of energetic electrons, which
  because of their high velocity are most sensitive to the structure of
  the magnetic field. We suggest that within our scenario we can explain
  two significant anomalies in the observations of energetic electrons
  in the outer heliosphere: the sudden decrease in the intensity of low
  energy electrons (0.02-1.5MeV) from the LECP instrument on Voyager 2 in
  2008 (Decker 2010); and the dramatic differences in intensity trends
  between Galactic Cosmic Ray Electrons (3.8-59MeV) at Voyager 1 and 2
  (McDonald 2010). We argue that these observations are a consequence
  of Voyager 2 leaving the sector region of disordered field in mid 2008
  and crossing into a region of unipolar laminar field.

---------------------------------------------------------
Title: Component Reconnexion at the Heliopause
Authors: Moore, T. E.; Alouani-Bibi, F.; Opher, M.; Toth, G.; McComas,
   D. J.
2010AGUFMSH21A1795M    Altcode:
  Extended X lines of component reconnection at the heliopause are derived
  from 3D MHD simulations of the steady state heliosphere (Alouani-Bibi
  et al 2010, Opher et al 2009). A similar study established this
  technique to describe the extended shape of reconnection X-lines at
  the magnetosphere, as result of its interaction with the interplanetary
  field of varying orientation (Moore et al., 2002). At the heliopause,
  reconnection X-line candidates are derived on the basis of geometrical
  criteria, allowing for shear angles between the interacting fields of
  less than 180 degree (Cowley 1976) and properties of the magnetic fields
  and flows outside (interstellar medium) and inside (interplanetary space
  beyond the termination shock) the heliopause. Kinetic effects addressed
  by Swisdak et al. (2009) and Opher et al. (2010) can inhibit large
  scale component reconnection, leading to more localized and nearly
  anti-parallel reconnection, possibly accounting for the persistent
  hot spot in IBEX heliopause ribbon.

---------------------------------------------------------
Title: Hydrogen deflection in the heliosphere and the effect of
    local interstellar magnetic field
Authors: Alouani-Bibi, F.; Opher, M.; Alexashov, D.; Toth, G.;
   Izmodenov, V.
2010AGUFMSH21A1800A    Altcode:
  The interaction of solar wind plasma with the local interstellar
  medium is studied using a coupled 3D Kinetic-MHD model. We show that
  the deflection of hydrogen atoms that penetrates the heliosphere is
  affected by the orientation and magnitude of the local interstellar
  magnetic field (BLISM) as well as by the kinetic treatment of neutral H
  atoms. We show that the observed deflection by Lallement et al (2005,
  2010) of interstellar neutral hydrogen flow at the inner-heliosphere
  is attained for different orientations and magnitudes of BLISM. The
  hydrogen deflection plane (HDP, that is the plane containing the He and
  H vector directions) is not a unique indicator for defining both the
  BLISM orientation and magnitude. This study is done for a high intensity
  field, BLISM (4.4µG), based on the analysis of the heliospheric
  asymmetries (Opher et al. 2009) which used multi-fluid model of
  solar wind and local interstellar interaction. Comparisons between
  the kinetic and multi-fluid treatments of neutrals showed substantial
  reduction in the hydrogen deflection for the kinetic approach.

---------------------------------------------------------
Title: Numerical simulation of the solar wind disturbances propagating
    to the distant heliosphere
Authors: Provornikova, E. A.; Opher, M.; Izmodenov, V.; Toth, G.
2010AGUFMSH51D1721P    Altcode:
  The propagation of waves in the solar wind plasma from 1 AU to the
  heliospheric boundaries is studied. First we consider the simple
  1D spherically symmetric model of the solar wind interaction with
  the local interstellar medium to describe the wave evolution in
  the supersonic solar wind flow in which parameters change with
  heliocentric distance. The hydrodynamics solution and the influence of
  the interstellar H atoms on the wave structure in the solar wind is
  discussed. The 2D kinetic-gasdynamic model (Izmodenov et al., 2005,
  2008) and 3D MHD model (Opher et al. 2009) are used to study the
  interaction of the different types of waves in the solar wind with
  the the termination shock and heliopause.

---------------------------------------------------------
Title: Coronal Heating by Surface Alfven Wave Damping: Implementation
    in MHD Modeling and Connection to Observations
Authors: Evans, R. M.; Opher, M.; Oran, R.; van der Holst, B.; Sokolov,
   I.; Frazin, R. A.; Gombosi, T. I.
2010AGUFMSH42A..07E    Altcode:
  We present results from the development of a solar wind model
  driven by Alfven waves with realistic damping mechanisms. We
  self-consistently introduce surface Alfven wave damping, which is
  characterized by transverse gradients in density. The plasma gradients
  set up a resonant layer, in which the waves dissipate energy to the
  wind. First, we applied surface Alfven wave damping in a solar wind
  model driven by a flat wave spectrum (van der Holst et al. 2010), and
  demonstrated its effect at the boundary of open and closed magnetic
  fields (Evans et al. 2010). Here we apply surface wave damping to
  a model which allows a Kolmogorov-type spectrum of Alfven waves to
  evolve in frequency space (Oran et al. 2010). We consider waves with
  frequencies lower than those damped in the chromosphere, and on the
  order of those dominating the heliosphere (0.0001 to 100 Hz). We
  provide wave dissipation as a function of frequency. We connect our
  modeling results to recent observations, including an estimation of
  resonant absorption damping by Verth, Terradas &amp; Goossens (2010)
  and density and temperature distributions using differential emission
  measure tomography by Vasquez, Frazin &amp; Manchester (2010), which
  we present as both direct and indirect evidence that this dissipation
  mechanism occurs and is important in the lower corona.

---------------------------------------------------------
Title: Evolution of Piled Up Compressions in Modeled CME Sheaths
    and the Resulting Sheath Structures
Authors: Das, I.; Opher, M.; Evans, R. M.; Gombosi, T. I.
2010AGUFMSH51E1732D    Altcode:
  We study Coronal Mass Ejection (CME) driven shocks and the resulting
  post shock structures in the lower corona (~ 2-7 Rsun). Two CMEs are
  erupted by modified Titov-Demoulin (TD) and Gibson-Low (GL) type flux
  ropes with Space Weather Modeling Framework. We observe a substantial
  pile up of density compression and a narrow region of plasma depletion
  layer (PDL) in the simulations. As the CME/flux rope moves and expands
  in solar wind medium, it pushes the magnetized material laying ahead
  of it. Hence, the magnetic field lines draping around the CME front are
  compressed in the sheath just ahead of the CME. These compressed field
  lines squeeze out the plasma sideways forming PDL in the region. Solar
  plasma being pushed and displaced from behind, forms a strong piled
  up compression (PUC) of density downstream of the PDL. Both CMEs have
  comparable propagation speeds while GL has larger expansion speed than
  TD due to its higher initial magnetic pressure. We argue that high
  CME expansion speed along with high solar wind density in the region
  are responsible for the large PUC found in the lower corona. In case
  of GL the PUC is much wider although the density compression ratio for
  both the cases are comparable. Although these simulations artificially
  initiate out-of-equilibrium CMEs and drive them in an artificial solar
  wind solution, we predict that PUCs, in general, will be large in the
  lower corona. This should affect the ion profiles of the accelerated
  solar energetic particles.

---------------------------------------------------------
Title: Simulations of Winds of Weak-lined T Tauri Stars. II. The
    Effects of a Tilted Magnetosphere and Planetary Interactions
Authors: Vidotto, A. A.; Opher, M.; Jatenco-Pereira, V.; Gombosi, T. I.
2010ApJ...720.1262V    Altcode: 2010arXiv1007.3874V
  Based on our previous work, we investigate here the effects on the
  wind and magnetospheric structures of weak-lined T Tauri stars
  due to a misalignment between the axis of rotation of the star
  and its magnetic dipole moment vector. In such a configuration,
  the system loses the axisymmetry presented in the aligned case,
  requiring a fully three-dimensional (3D) approach. We perform 3D
  numerical magnetohydrodynamic simulations of stellar winds and
  study the effects caused by different model parameters, namely the
  misalignment angle θ<SUB> t </SUB>, the stellar period of rotation,
  the plasma-β, and the heating index γ. Our simulations take into
  account the interplay between the wind and the stellar magnetic field
  during the time evolution. The system reaches a periodic behavior with
  the same rotational period of the star. We show that the magnetic
  field lines present an oscillatory pattern. Furthermore, we obtain
  that by increasing θ<SUB> t </SUB>, the wind velocity increases,
  especially in the case of strong magnetic field and relatively rapid
  stellar rotation. Our 3D, time-dependent wind models allow us to study
  the interaction of a magnetized wind with a magnetized extrasolar
  planet. Such interaction gives rise to reconnection, generating
  electrons that propagate along the planet's magnetic field lines
  and produce electron cyclotron radiation at radio wavelengths. The
  power released in the interaction depends on the planet's magnetic
  field intensity, its orbital radius, and on the stellar wind local
  characteristics. We find that a close-in Jupiter-like planet orbiting
  at 0.05 AU presents a radio power that is ~5 orders of magnitude larger
  than the one observed in Jupiter, which suggests that the stellar wind
  from a young star has the potential to generate strong planetary radio
  emission that could be detected in the near future with LOFAR. This
  radio power varies according to the phase of rotation of the star. For
  three selected simulations, we find a variation of the radio power of a
  factor 1.3-3.7, depending on θ<SUB> t </SUB>. Moreover, we extend the
  investigation done in Vidotto et al. and analyze whether winds from
  misaligned stellar magnetospheres could cause a significant effect
  on planetary migration. Compared to the aligned case, we show that
  the timescale τ<SUB> w </SUB> for an appreciable radial motion of
  the planet is shorter for larger misalignment angles. While for the
  aligned case τ<SUB> w </SUB> ~= 100 Myr, for a stellar magnetosphere
  tilted by θ<SUB> t </SUB> = 30°, τ<SUB> w </SUB> ranges from ~40 to
  70 Myr for a planet located at a radius of 0.05 AU. Further reduction
  on τ<SUB> w </SUB> might occur for even larger misalignment angles
  and/or different wind parameters.

---------------------------------------------------------
Title: Radio emission from close-in giant planets around young stars
Authors: Vidotto, A. A.; Opher, M.; Jatenco-Pereira, V.; Gombosi, T. I.
2010epsc.conf..233V    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Energetic protons accelerated by a Coronal Mass Ejection
    (CME)-driven traveling plasma structures in the solar corona
Authors: Kozarev, Kamen Asenov; Das, Indrajit; Schwadron, Nathan;
   Opher, Merav; Desai, Mihir; Gombosi, Tamas
2010shin.confE..92K    Altcode:
  A growing body of theoretical and observational research suggests that
  Solar Energetic Particles (SEP) gain most of their energy at shocks
  relatively close to the Sun. Interplanetary shocks have been quite well
  studied, thanks to in situ measurements of energetic particles near
  Earth and throughout the solar system. Many bursts of energetic charged
  particles observed close to Earth are not directly associated with
  shocks that pass by Earth. This suggests that energetic particles could
  be formed much lower, in the solar corona, possibly by shocks that form
  near the Sun or through magnetic reconnection. We have used results from
  a magnetohydrodynamic (MHD) simulation of a coronal mass ejection (CME)
  in the solar corona, combined with an energetic particle propagation
  and acceleration model, in order to investigate how energetic protons
  respond to an enhanced traveling plasma structure and shock in the
  corona. This work will help address the question of whether and how
  efficient CME-driven plasma structures and shocks close to the Sun
  are in accelerating suprathermal particle populations to high energies.

---------------------------------------------------------
Title: Surface Alfven Wave Contribution to Coronal Heating in a
    Wave-Driven Solar Wind Model
Authors: Evans, Rebekah Minnel; Opher, Merav; Oran, Rona; Sokolov,
   Igor V.; van der Holst, Bart; Gombosi, Tamas I.
2010shin.confE.119E    Altcode:
  We present results from the development of a solar wind model driven
  by a spectrum of Alfven waves with realistic damping mechanisms in the
  Space Weather Modeling Framework. Whereas other works have focused on
  the dissipation of wave energy in closed magnetic field regions or along
  open polar field lines, we emphasize here the boundary between these
  two regions as a source for coronal heating and wind acceleration. This
  region is characterized by gradients in density and magnetic field,
  that set up a resonant layer in which surface Alfven waves arise and
  dissipate their energy to the solar wind. Observations of latitudinal
  density distributions at 1.035-1.225 solar radii from differential
  emission measure tomography (Vasquez, Frazin &amp; Manchester 2009)
  show density enhancements at the boundary of open and closed magnetic
  fields, which supports the presence of surface Alfven wave damping in
  this region. We utilize a first principle solar wind model within the
  Space Weather Modeling Framework. The wave transport equation, including
  wave advection and dissipation, is coupled to the magnetohydrodynamics
  equations for the plasma. We extend this model to include surface
  Alfven wave damping. We provide the first global damping length map for
  surface Alfven waves in a realistic background solar wind. We quantify
  the contribution of the damping to coronal heating and acceleration of
  the wind. <P />The boundary conditions for this solar wind model are
  obtained from observations and a semi-empirical model. The velocities
  at 1AU obtained from the semi-empirical Wang-Sheeley-Arge model in
  combination with conservation of the total energy density along the
  magnetic field lines determines the Alfven wave pressure at the lower
  coronal boundary. The electron density and temperature at the lower
  solar boundary are obtained from the differential emission measure
  tomography applied to the extreme ultraviolet images of the STEREO A
  and B spacecraft. <P />This new solar wind model is validated with ACE
  data for Carrington rotation 2077 (2008, November 20 through December
  17). Overall, the simulated results at 1AU match the ACE observations
  rather well.

---------------------------------------------------------
Title: Is the Magnetic Field in the Heliosheath Sector Region and
    in the Outer Heliosheath Laminar?
Authors: Opher, Merav; Drake, J. F.; Swisdak, M.
2010shin.confE..65O    Altcode:
  All the current global models are based on our understanding that
  the magnetic field in the outer heliosheath close to the heliopause
  is laminar. We argue that in the outer heliosheath, close to the
  heliopause, the heliospheric magnetic field is in fact not laminar but
  instead filled with magnetic islands. Recently, we proposed (Drake et
  al. 2009) that the annihilation of the "sectored" magnetic field within
  the heliosheath as it is compressed on its approach to the heliopause
  produces the anomalous cosmic rays, ACRs. In this process energetic
  electrons are also produced. As a product of the annihilation of the
  sectored magnetic field, magnetic islands are produced. These magnetic
  islands will be convected with the flows as the sector boundary
  is carried to higher latitudes filling the outer heliosheath. We
  further argue that the magnetic islands will propagate upstream and
  affect the structure of the magnetic field in the heliosheath sector
  region making it disorganized. Due to the increased pressure of the
  interstellar magnetic field the sector boundary is carried mostly to
  the northern hemisphere (Opher et al. 2006, 2007). We argue that the
  sector boundary fills a large portion of the northern part of the
  heliosphere with a smaller extension in the southern hemisphere. We
  therefore predict an asymmetry of the magnetic structure between the
  northern and southern hemispheres and between the heliosheath sector
  region and the field outside of it. Within this scenario we are able
  to explain the the sudden decrease seen in mid 2008 in Voyager 2 in
  the low energy electrons (0.02-1.5MeV) from the LECP instrument; in the
  low energy Galactic Cosmic Ray Electrons (2-14MeV) and the north-south
  asymmetry seen in the Galactic Cosmic Ray Electrons between Voyager 1
  and 2 intensities. We argue that these observations are a consequence
  of Voyager 2 leaving the sector region of disorganized field in mid
  2008 and crossing into a region of unipolar organized laminar field.

---------------------------------------------------------
Title: The effects of the solar cycle variations on the solar wind
    properties at the heliospheric boundaries
Authors: Provornikova, Elena Aleksandrovna; Izmodenov, V. V.; Opher,
   M.; Malama Y., G.
2010shin.confE...7P    Altcode:
  The propagation and evolution of fluctuations of the solar wind
  are studied in the frame of the two-dimensional non-stationary
  kinetic-gasdynamic model of the interaction of solar wind with the
  local interstellar medium (Izmodenov et al., 2005, 2008). For this
  purpose we analyzed how various types of waves in the solar wind pass
  through the termination shock and heliopause. Results show that solar
  wind fluctuations strongly influence the location of heliospheric
  boundaries. Using OMNI data for solar wind parameters at 1 a.u. for
  the last 3 solar cycles we investigate the variation of the distances
  to the termination shock and heliopause. Particularly we focus on
  the questions how the anomalously low solar wind dynamic pressure
  during 2008-2009 affects the locations of the termination shock and
  the heliopause at the present time and in the future.Voyager 2 has
  crossed the termination shock in August 2007 and now measures the
  plasma parameters in the inner heliosheath. In this work we estimate
  the time when Voyager 2 might cross the heliopause. Also the solar
  wind parameters along the trajectory of Voyager 2 obtained in the model
  are compared with experimental data obtained on the board of Voyager 2.

---------------------------------------------------------
Title: The Imprint of the Very Local Interstellar Magnetic Field in
    Simulated Energetic Neutral Atom Maps
Authors: Prested, C.; Opher, M.; Schwadron, N.
2010ApJ...716..550P    Altcode:
  The interaction of the solar wind with the very local interstellar
  medium (VLISM) forms the boundaries of the heliosphere. A strong
  asymmetry of the heliosphere was found both directly by the Voyager
  probes and indirectly from measurements of the deflection of neutral
  hydrogen. The most likely source of this asymmetry is from the
  interstellar magnetic field, the properties of which are highly
  unconstrained. Energetic neutral atom (ENA) images will provide an
  additional method to view the heliosphere and infer the interstellar
  magnetic field. This paper investigates the imprint of the interstellar
  magnetic field on simulated energetic neutral atom all-sky maps. We
  show that a significant source of 0.5-1 keV ENAs may originate from the
  outside of the heliopause, if a strong suprathermal population exists
  in the VLISM. In simulations, a strong outer heliosheath ENA feature
  appears near the nose of the heliosphere. A weaker, complementary
  feature is also present consisting entirely of inner heliosheath
  ENAs. From this feature the direction of the interstellar magnetic
  field can be easily inferred.

---------------------------------------------------------
Title: Shocks in heliophysics
Authors: Opher, Merav
2010hssr.book..193O    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Surface Alfven Wave Contribution to Coronal Heating in a
    Wave-Driven Solar Wind Model
Authors: Evans, Rebekah M.; Opher, M.; Oran, R.; Sokolov, I. V.
2010AAS...21640719E    Altcode: 2010BAAS...41..862E
  We present results from the development of a solar wind model driven
  by Alfven waves with realistic damping mechanisms. We investigate the
  contribution of surface Alfven wave damping to the heating of the
  corona and acceleration of the solar wind. These waves are present
  and damp in regions of strong gradients in density or magnetic field
  (e.g., the border between open and closed magnetic fields). Recently
  Oran et al. (2009) implemented a first principle solar wind model
  driven by a spectrum of Alfven waves into the Space Weather Modeling
  Framework. The wave transport equation, including wave advection
  and dissipation, is coupled to the MHD equations for the wind. The
  waves contribute to the momentum and energy of the wind through the
  action of wave pressure. Here we extend this model to include surface
  Alfven wave damping as a dissipation mechanism, considering waves with
  frequencies lower than those damped in the chromosphere and on the order
  of those dominating the heliosphere (0.0001 to 100 Hz.) We demonstrate
  the influence of the damping by quantifying the differences between
  a solution that includes surface Alfven wave damping and one driven
  solely by Alfven wave pressure. We relate to possible observational
  signatures of heat transfer by surface Alfven wave damping. This work is
  the first to study surface Alfven waves self-consistently as an energy
  driven for the solar wind in a 4D (three in space and one in frequency)
  environment. <P />This work is supported by the NSF CAREER Grant.

---------------------------------------------------------
Title: Sheath Flows and Reconnection in the Lower Corona: New
    Diagnostics for the Initial Orientation of the Ejecta of Coronal
    Mass Ejections
Authors: Opher, Merav; Evans, R. M.
2010AAS...21640603O    Altcode: 2010BAAS...41..880O
  The structure of the magnetic field of the ejecta of a coronal mass
  ejection (CME) is not well known near the Sun. We propose using
  the subsonic plasma flows in the CME-sheath to constrain the CME
  field direction. We draw an analogy to the outer heliosphere, where
  Opher et al. (2009) used Voyager 2 measurements of the solar wind in
  the heliosheath to constrain the strength and direction of the local
  interstellar magnetic field. We simulate three ejections in a realistic
  background in the solar minimum conditions of 1997 May with the Space
  Weather Modeling Framework. Each ejection has the same initial energy,
  but a different magnetic field orientation in relation to the overall
  orientation of the active region field. We show that the sheath flows
  are sensitive to the direction of the initial magnetic field, and
  differ by more than 60 degrees when the CME-driven shock is located
  at 4.5 solar radii. Unlike the heliosheath flows, the CME-sheath
  flows are affected not only by the initial ejecta orientation but
  by the CME's evolution in the lower corona as well. We show that
  the evolutions differ because of the locations and intensities of
  reconnection events. We distinguish between the initial reconnection
  between the ejecta and the overlying field of the active region, and
  further reconnection events with the global solar coronal field (which
  occur beyond 2 solar radii). This late reconnection causes bulk motion
  and heating in the ejecta and sheaths, which affects the size of the
  CME-pause and the velocity profile of the CME. We suggest identifying
  the orientation of the magnetic field ejecta through velocity profiles
  in the lower corona and in situ CME-sheath flow measurements. These
  results provide new diagnostics to identify different initial CME
  magnetic field orientations without need for direct measurement.

---------------------------------------------------------
Title: Magnetic fields in the Local ISM and the Local Bubble
Authors: Opher, Merav
2010AAS...21620103O    Altcode:
  In recent years it become clear that magnetic field effects, plays
  an important role in the Heliosphere, from shaping it and possible
  being responsible for the asymmetries observed in the Voyager data
  (e.g., Opher et al. 2007, 2009), but the strength and orientation of
  the field in the local interstellar medium near the heliosphere has
  been poorly constrained. Previous estimates of the field strength
  range from 1.8-2.5 μG and the field was thought to be parallel to
  the Galactic plane or inclined by 38-60 ° (Lallement et al. 2005)
  or 60-90° (Opher et al. 2007) to this plane. These estimates relied
  either on indirect observational inferences or modeling in which the
  interstellar neutral hydrogen was not taken into account. We will
  discuss recent work that indicate that based on asymmetries detected
  by Voyager 1 and 2 and measurements of the deflection of the solar
  wind plasma flows in the heliosheath (Opher et al. 2009) indicate
  that the field strength in the local interstellar medium is strong,
  between 4-5 μG. The field is tilted 20-30° from the interstellar
  medium flow direction (resulting from the peculiar motion of the Sun
  in the Galaxy) and is at an angle of about 30° from the Galactic
  plane. We will relate our findings with the most recent results of
  IBEX that indicate that the interstellar magnetic field has a strong
  signature in the emission of energetic neutrals. We will discuss the
  possible implications of a strong magnetic field for the environment
  in the Local ISM and the Local Bubble.

---------------------------------------------------------
Title: The Vector Direction of the Interstellar Magnetic Field
    Outside the Heliosphere
Authors: Swisdak, M.; Opher, M.; Drake, J. F.; Alouani Bibi, F.
2010ApJ...710.1769S    Altcode: 2010arXiv1001.0589S
  We propose that magnetic reconnection at the heliopause (HP) only occurs
  where the interstellar magnetic field points nearly anti-parallel to
  the heliospheric field. By using large-scale magnetohydrodynamic (MHD)
  simulations of the heliosphere to provide the initial conditions for
  kinetic simulations of HP reconnection, we show that the energetic
  pickup ions downstream from the solar wind termination shock induce
  large diamagnetic drifts in the reconnecting plasma and stabilize
  non-anti-parallel reconnection. With this constraint, the MHD
  simulations can show where HP reconnection most likely occurs. We
  also suggest that reconnection triggers the 2-3 kHz radio bursts that
  emanate from near the HP. Requiring the burst locations to coincide
  with the loci of anti-parallel reconnection allows us to determine,
  for the first time, the vector direction of the local interstellar
  magnetic field. We find it to be oriented toward the southern solar
  magnetic pole.

---------------------------------------------------------
Title: A Magnetic Reconnection Mechanism for the Generation of
    Anomalous Cosmic Rays
Authors: Drake, J. F.; Opher, M.; Swisdak, M.; Chamoun, J. N.
2010ApJ...709..963D    Altcode: 2009arXiv0911.3098D
  The recent observations of the anomalous cosmic ray (ACR) energy
  spectrum as Voyager 1 and Voyager 2 crossed the heliospheric termination
  shock have called into question the conventional shock source of
  these energetic particles. We suggest that the sectored heliospheric
  magnetic field, which results from the flapping of the heliospheric
  current sheet, piles up as it approaches the heliopause, narrowing the
  current sheets that separate the sectors and triggering the onset of
  collisionless magnetic reconnection. Particle-in-cell simulations reveal
  that most of the magnetic energy is released and most of this energy
  goes into energetic ions with significant but smaller amounts of energy
  going into electrons. The energy gain of the most energetic ions results
  from their reflection from the ends of contracting magnetic islands,
  a first-order Fermi process. The energy gain of the ions in contracting
  islands increases their parallel (to the magnetic field B) pressure
  p <SUB>par</SUB> until the marginal fire-hose condition is reached,
  causing magnetic reconnection and associated particle acceleration to
  shut down. Thus, the feedback of the self-consistent development of
  the energetic ion pressure on reconnection is a crucial element of any
  reconnection-based, particle-acceleration model. The model calls into
  question the strong scattering assumption used to derive the Parker
  transport equation and therefore the absence of first-order Fermi
  acceleration in incompressible flows. A simple one-dimensional model
  for particle energy gain and loss is presented in which the feedback
  of the energetic particles on the reconnection drive is included. The
  ACR differential energy spectrum takes the form of a power law with
  a spectral index slightly above 1.5. The model has the potential to
  explain several key Voyager observations, including the similarities
  in the spectra of different ion species.

---------------------------------------------------------
Title: Preferential Low-Latitude Acceleration and Transport of
    Low-Energy Anomalous Cosmic Rays
Authors: Hill, Matthew; Drake, James; Opher, Merav
2010cosp...38.1666H    Altcode: 2010cosp.meet.1666H
  During the last decade the encounters by the Voyager 1 and 2
  spacecraft with the termination shock and continuing cruise through
  the heliosheath have upset the classical anomalous cosmic ray (ACR)
  paradigm, which has interstellar neutral atoms being ionized, picked up
  by the solar wind, and accelerated at essentially all regions of the
  termination shock. Observations show that ACRs are not accelerated
  at the termination shock, at least not at the locations of the
  Voyager encounters. ACR transport is also supposed to be dominated
  by drift motion arising from the curvature and gradients of the
  global heliospheric magnetic field; the well-known drift pattern
  of cosmic rays down along the poles and out along the heliospheric
  current sheet during the so called A &gt; 0 solar cycles (and reverse
  pattern during A &lt; 0) is considered a hallmark of the classic
  theory. Additionally the observed striking similarity of the spectral
  slope of suprathermal ions across wide regions and conditions in the
  heliosphere has forced a general rethinking of the role of diffusive
  shock acceleration. We present the results of two independent
  lines of inquiry. First, recent theoretical and particle-in-cell
  simulation work has combined determination of the physical cause for
  the special spectral form with a proposed mechanism for the source
  of ACRs—explained by the conversion of magnetic energy into kinetic
  energy due to the annihilation of magnetic flux near the heliopause,
  at low latitudes. Second, observational study of ACR transport during
  the A &gt; 0 cycle shows—for low-energy ions of a given species
  (actually for low rigidities, less than 2 GV, when all species are
  considered)—no evidence for a strong positive latitudinal intensity
  gradient, as predicted. Quite the opposite is true. For the lowest
  rigidities these gradients are negative, as large as -15%/degree. This
  and other work suggests that the low-latitude region is the region where
  ACR activity is most significant. We will compare the theoretical and
  observational results and discuss the implications for the surprising
  dearth of ACRs observed during the termination shock encounters,
  and the subsequent variations in the heliosheath.

---------------------------------------------------------
Title: Simulations of Winds of Weak-Lined T Tauri Stars: The Magnetic
    Field Geometry and The Influence of the Wind on Giant Planet Migration
Authors: Opher, Merav; Vidotto, A.; Jatenco-Pereira, V.; Gombosi, T.
2010AAS...21534902O    Altcode: 2010BAAS...42..531O
  By means of numerical simulations, we investigate magnetized stellar
  winds of pre-main sequence stars. In particular we analyze under which
  circumstances these stars will present elongated magnetic features
  (e.g., helmet streamers, slingshot prominences, etc). We focus on
  weak-lined T Tauri stars, as the presence of the tenuous accretion
  disk is not expected to have strong influence on the structure of
  the stellar wind. We show that the plasma-beta parameter (the ratio
  of thermal to magnetic energy densities) is a decisive factor in
  defining the magnetic configuration of the stellar wind. Using initial
  parameters within the observed range for these stars, we show that the
  coronal magnetic field configuration can vary between a dipole-like
  configuration and a configuration with strong collimated polar lines
  and closed streamers at the equator (multi component configuration for
  the magnetic field). We show that elongated magnetic features will
  only be present if the plasma-beta parameter at the coronal base is
  beta0 &lt;&lt; 1. Using our self-consistent 3D MHD model, we estimate
  for these stellar winds the time scale of planet migration due to drag
  forces exerted by the stellar wind on a hot-Jupiter. In contrast to the
  findings of Lovelace et al. (2008), who estimated such time-scales using
  the Weber \&amp; Davis model, our model suggests that the stellar wind
  of these multi component coronae are not expected to have significant
  influence on hot-Jupiters migration. Further simulations are necessary
  to investigate this result under more intense surface magnetic field
  strengths ( 2-3kG) and higher coronal base densities, as well as in
  a tilted stellar magnetosphere.

---------------------------------------------------------
Title: A magnetic reconnection mechanism for the generation of
    anomalous cosmic rays
Authors: Drake, James; Opher, Merav; Swisdak, Marc; Chamoun, Jacob
2010cosp...38.1608D    Altcode: 2010cosp.meet.1608D
  The recent observations of the anomalous cosmic ray (ACR) energy
  spectrum as Voyagers 1 and 2 crossed the heliospheric termination
  shock have called into question the conventional shock source of
  these energetic particles. We suggest that the sectored heliospheric
  magnetic field, which results from the flapping of the heliospheric
  current sheet, piles up as it approaches the heliopause, narrowing
  the current sheets that separate the sectors and triggering the onset
  of collisionless magnetic reconnection. Particle-in-cell simulations
  reveal that the current layers break up into a turbulent bath of
  magnetic islands that merge to release a large fraction of the energy
  in the sectored magnetic field. Most of the magnetic energy goes into
  energetic ions with significant but smaller amounts of energy going into
  electrons. The dominant acceleration mechanism is through reflection in
  contracting islands, a first-order Fermi mechanism. Particle energy gain
  is regulated by the approach to the marginal firehose condition. The
  ACR differ-ential energy spectrum for all of the ion species takes
  the form of a power law with a spectral index slightly above 1.5,
  which is consistent with observations.

---------------------------------------------------------
Title: Global Asymmetries in the Heliosphere: Signature of the
    Interstellar Magnetic Field
Authors: Opher, Merav; Alouani-Bibi, Fathallah; Izmodenov, Vladislav;
   Richardson, John; Toth, Gabor; Gombosi, Tamas
2010cosp...38.1604O    Altcode: 2010cosp.meet.1604O
  In recent years it become clear that magnetic field effects, plays an
  important role in the Heliosphere, from shaping it and possible being
  responsible for the asymmetries observed in the Voyager data (e.g.,
  Opher et al. 2007, 2009). However, the strength and orientation of
  the field in the local interstellar medium near the heliosphere has
  been poorly constrained. Previous estimates of the field strength
  range from 1.8-2.5 G and the field was thought to be parallel to the
  Galactic plane or inclined by 38-60 (Lallement et al. 2005) or 60-90
  (Opher et al. 2007) to this plane. These estimates relied either on
  indirect observational inferences or modeling in which the interstellar
  neutral hydrogen was not taken into account. We will discuss recent
  work that indicate that based on asymmetries detected by Voyager 1
  and 2 and measurements of the deflection of the solar wind plasma
  flows in the heliosheath (Opher et al. 2009) indicate that the field
  strength in the local interstellar medium is strong, between 4-5 G
  (Other works such as Izmodenov 2009; Pogorelov et al. 2009; Ratkiewickz
  et al. 2009 found similar strength). The field is tilted 20-30 from
  the interstellar medium flow direction (resulting from the peculiar
  motion of the Sun in the Galaxy) and is at an angle of about 30 from
  the Galactic plane. We will discuss the effect of such magnetic field
  in the global asymmetries of the heliosphere. We further will comment
  on the effect on asymmetries of our recent model of Kinetic-MHD model
  treating the neutrals in kinetic fashion (Alouani-Bibi et al. 2010). We
  will relate our findings with the most recent results of IBEX that
  indicate that the interstellar magnetic field has a strong signature
  in the emission of energetic neutrals.

---------------------------------------------------------
Title: Relationship between Flow and Magnetic Field in Coronal
    Mass Ejections
Authors: Evans, Rebekah M.; Opher, M.
2010AAS...21532205E    Altcode: 2010BAAS...42..324E
  Magnetic fields impact the dynamics of astrophysical plasmas in
  many regimes, from galaxies to stars to planets. This universal
  process suggests that knowledge can be gained by doing comparative
  analysis in different regimes. Recently, Opher et al. 2009 used a 3D
  magnetohydrodynamics (MHD) simulation of the heliosphere to show that
  the flow inside the heliosheath is sensitive to the direction of the
  magnetic field in the interstellar medium. Direct measurements of the
  flows in this region by Voyager 2 allowed for the best estimates to
  date of the strength and direction of the local interstellar magnetic
  field. <P />Here we draw an analogy between the heliosphere and
  Coronal Mass Ejections (CMEs). Like the interstellar magnetic field,
  the structure of the magnetic field in a CME eruption is not well known
  near the Sun, and several initiation models exist. We characterize
  plasma flows in the CME-sheath - the subsonic flow region between the
  CME-driven shock and the location of pressure balance between the solar
  wind and the ejected material (analogous to the heliosheath). Using a
  3D MHD simulation, we investigate the relationship between these flows
  and the orientation of the CME's magnetic field. This result provides
  a new diagnostic to probe the 3D magnetic field structure of CMEs,
  without need for direct measurement. <P />This research is supported
  by the NSF CAREER Grant and LWS.

---------------------------------------------------------
Title: The possibility of magnetic reconnection at the heliopause
Authors: Swisdak, Marc; Drake, James; Opher, Merav
2010cosp...38.1606S    Altcode: 2010cosp.meet.1606S
  We propose that magnetic reconnection at the heliopause only occurs
  where the interstellar magnetic field points nearly anti-parallel to
  the heliospheric field. By using large-scale mag-netohydrodynamic
  simulations of the heliosphere to provide the initial conditions
  for kinetic simulations of heliopause reconnection we show that the
  energetic pickup ions downstream from the solar wind termination shock
  induce large diamagnetic drifts in the reconnecting plasma and stabilize
  non-anti-parallel reconnection. With this constraint the MHD simulations
  can show where heliopause reconnection most likely occurs. We also
  suggest that reconnection triggers the 2-3 kHz radio bursts that emanate
  from near the heliopause. Requiring the burst locations to coincide
  with the loci of anti-parallel reconnection allows us to determine,
  for the first time, the vector direction of the local interstellar
  magnetic field. We find it to be oriented towards the southern solar
  magnetic pole.

---------------------------------------------------------
Title: Hybrid simulation of interstellar wind interaction with solar
    wind plasma
Authors: Izmodenov, V.; Alouani Bibi, F.; Opher, M.; Aleksashov, D.;
   Toth, G.
2009AGUFMSH21A1496I    Altcode:
  Iterative Hybrid (Kinetic / MHD) approach is used to study the
  interaction of the partly ionized interstellar wind with the fully
  ionized solar wind plasma. Charged and neutral components are coupled
  though charge exchange. The location and topology (e.g. asymmetries) of
  the Heliospheric boundaries (BS, HP and TS) are analyzed and compared
  to previous multi-fluid approach, where the kinetic description of
  neutrals was approximated by hydrodynamic multi neutral species (4
  species). Based on analysis of global heliospheric asymmetries, we use
  our best estimate for the interstellar magnetic field orientation and
  intensity. The iterative scheme is performed using the ionized fluid
  properties obtained with our 3D MHD code as a source term for the
  neutral H, which is treated by solving the Boltzmann Kinetic equation,
  the output of the later is fed back to the MHD code as plasma source
  terms. Each of these phases is allowed to reach a steady state before
  each iteration.

---------------------------------------------------------
Title: Surface Alfven Wave Damping in a Solar Wind Simulation Driven
    by Alfven Waves
Authors: Evans, R. M.; Opher, M.; Oran, R.; Sokolov, I.
2009AGUFMSH53A1309E    Altcode:
  We present results in an effort to develop a solar wind model driven
  by Alfven waves with realistic damping mechanisms. Here we investigate
  the contribution of surface Alfven wave damping to the heating of the
  solar wind in minima conditions. These waves are present and damp in
  regions of strong gradients in density or magnetic field (e.g., the
  border between open and closed magnetic field lines). By considering
  the geometry of open field lines and the background solar wind in
  these regions, we showed that surface Alfven wave contribution to
  heating is on the order of the heating by a variable polytropic index
  in the semiempirical thermodynamics model of Cohen et al. (Evans et
  al. 2009). Recently Oran et al. implemented a first principle steady
  state solar wind driven by a spectrum of Alfven waves in the SWMF. The
  waves contribute to the momentum and the energy of the wind. The
  wave transport equation, including wave advection and dissipation,
  is coupled to the MHD equations for the wind. In this work we extend
  this model to include surface Alfven wave damping, considering waves
  with frequencies lower than those that are damped in the chromosphere
  and on the order of those dominating the heliosphere (0.0001 to 100
  Hz.) We compare to results of the variable polytropic index model, and
  a wind driven solely by Alfven wave pressure. This work is the first to
  study surface Alfven waves self-consistently as an energy driven for the
  solar wind in a 4D (three in space and one in frequency) environment.

---------------------------------------------------------
Title: Comparison of Model ENAs Produced from Heliospheric Multi-fluid
    MHD with the First All-Sky ENA Maps
Authors: Prested, C. L.; Schwadron, N. A.; Opher, M.; McComas, D. J.;
   Funsten, H. O.; Fuselier, S. A.
2009AGUFMSH21B1509P    Altcode:
  Using a multi-fluid MHD plus neutrals model of the heliosphere,
  we produce and compare model energetic neutral atom (ENA) maps to the
  first observations of the Interstellar Boundary Explorer (IBEX) mission,
  specifically comparing to data from the IBEX - Hi sensor at energies
  of 0.5 keV to 6 keV. We explore how model ENA maps are affected by
  varying several parameters including the Very Local Interstellar Medium
  (VLISM) magnetic field strength and orientation, the assumed plasma
  distribution of the inner heliosheath, and the plasma distribution
  of the outer heliosheath. If a suprathermal population exists in the
  outer heliosheath, then at energies &lt; 2 keV the high density region
  of VLISM plasma and neutrals along the nose of the heliopause produces
  as many, or more, ENAs as the inner heliosheath. We provide a system
  of metrics for comparison with the IBEX data and discuss the extent to
  which our model agrees or disagrees with the first complete ENA sky
  maps. Based on the metric results, we suggest future improvements on
  our model.

---------------------------------------------------------
Title: A reconnection mechanism for the generation of anomalous
    cosmic rays
Authors: Drake, J. F.; Swisdak, M. M.; Opher, M.; Schoeffler, K. M.
2009AGUFMSH24A..06D    Altcode:
  The recent observations of the anomalous cosmic ray (ACR) energy
  spectrum as Voyagers 1 and 2 crossed the heliospheric termination
  shock have called into question the conventional shock source of
  these energetic particles. We suggest that the sectored heliospheric
  magnetic field, which results from the flapping of the heliospheric
  current sheet, piles up as it approaches the heliopause, narrowing
  the current sheets that separate the sectors and triggering the onset
  of collisionless magnetic reconnection. Particle-in-cell simulations
  reveal that most of the magnetic energy goes into energetic ions with
  significant but smaller amounts of energy going into electrons. The
  most energetic ions gain energy as they reflect from contracting
  magnetic islands, a first order Fermi process. The simulations also
  reveal that the mirror and firehose conditions play an essential role
  in the reconnection dynamics and particle acceleration. An analytic
  model is constructed in which the Fermi drive, modulated by the
  approach to firehose marginality, is balanced by convective loss. The
  ACR differential energy spectrum takes the form of a power law with
  a spectral index slightly above 1.5. The model has the potential to
  explain several key ACR observations, including the similarities in
  the spectra of different ion species.

---------------------------------------------------------
Title: Acceleration of Anomalous Cosmic Rays via Reconnection in
    the Heliosheath
Authors: Lazarian, A.; Opher, M.
2009AGUFMSH21A1498L    Altcode:
  We discuss a model of cosmic ray acceleration that accounts for the
  observations of anomalous cosmic rays (ACRs) by Voyager 1 and 2. The
  model appeals to fast magnetic reconnection rather than shocks as the
  driver of acceleration. The ultimate source of energy is associated
  with magnetic field reversals that occur in the heliosheath. It is
  expected that the magnetic field reversals will occur throughout
  the heliosheath, but especially near the heliopause where the flows
  slow down and diverge with respect to the interstellar wind and also
  in the boundary sector in the heliospheric current sheet. While the
  first-order Fermi acceleration theory within reconnection layers is
  in its infancy, the predictions do not contradict the available data
  on ACR spectra measured by the spacecraft. We argue that the Voyager
  data are one of the first pieces of evidence favoring the acceleration
  within regions of fast magnetic reconnection, which we believe to be a
  widely spread astrophysical process. Meridional iew of the boundary of
  the heliospheric current sheet and how the opposite sectors get tighter
  closer to the heliopause. There in the presence of turbulence fast
  reconnection produces first order Fermi acceleration of the anomalous
  cosmic rays.

---------------------------------------------------------
Title: The link between pick-up ions and energetic neutral atoms
Authors: Alouani Bibi, F.; Opher, M.; Prested, C. L.; Schwadron,
   N. A.; Toth, G.
2009AGUFMSH21B1508A    Altcode:
  We study the source (starting inside the termination shock) and
  transport of pick-up ions (PUI) linked to the generation of energetic
  neutral atoms (ENA). We use a three dimensional multi-fluid (seven
  populations: thermal protons, four neutral populations, PUI ions and
  ENA) magneto-hydrodynamic model. PUIs are injected into the simulation
  grid as an inner-boundary condition at 30 AU and appropriate PUI source
  terms are included inside the heliopause. At the inner-boundary, the
  PUI initial density and temperature are derived analytically assuming
  a Vasyliunas-Siscoe distribution function for these suprathermal
  particles. PUI production beyond the heliopause is neglected. The
  variations in the non-thermal solar wind pressure inside the heliopause
  as a result of PUI production and convection are analyzed. Implications
  of these pressure variations on the heliospheric boundaries and
  resulting ENA maps are discussed.

---------------------------------------------------------
Title: Orientation and Magnitude of the Interstellar Magnetic Field
    from Heliosheath Flows
Authors: Opher, M.; Alouani Bibi, F.; Toth, G.; Richardson, J. D.;
   Izmodenov, V.; Gombosi, T. I.
2009AGUFMSH32A..04O    Altcode:
  We show that the heliosheath flows can be used as a new and highly
  important data set to determine the interstellar magnetic field
  orientation and magnitude. We use a new three-dimensional model
  that includes both the plasma and the neutral H atoms as well as the
  interplanetary and interstellar magnetic fields. The field orientation
  and magnitude that we derive differ substantially from the those
  previously reported (Opher et al. 2006, 2007). We comment on the
  consequences of this result on the heliospheric global asymmetries (such
  as the field-aligned streaming of low energy particles, the distance of
  the termination shock, and the shape of the heliopause). We comments
  as well on the inference on the conditions on the local interstellar
  medium. We study the effect of numerical resolution and non-stationary
  on the model shock and find them to be negligible. We also comment
  on the possible effects of the tilt of current sheet, not included
  currently in the model (which at the time of the termination shock
  crossings of Voyager 1 and 2 was about 30 degrees). We present a
  simulation with a scaled down heliosphere which includes a dynamic
  time dependent current sheet.

---------------------------------------------------------
Title: The Heliopause Reconnection X-line
Authors: Olson, D. K.; Moore, T. E.; Bibi, F. A.; Opher, M.; Coplan,
   M. A.
2009AGUFMSH21B1507O    Altcode:
  The behavior of the interaction between the magnetosphere and the
  interplanetary magnetic field and the formation of reconnection
  X-lines have previously been modeled (Moore et al., JGR 2002) and
  observed (Pu et al., JGR 2007). We apply a similar method to examining
  the interaction of the heliosphere with the interstellar magnetic
  field. While today it is difficult to make direct measurements of the
  heliopause, an understanding of the characteristics of this interaction
  can help us compare models of the heliosphere to new observations of
  the interstellar boundary. Using a 3D magnetohydrodynamic simulation
  (Opher et al., Science 2007), a solution is obtained for a specified
  interstellar field. From this solution, we can identify the heliopause
  by selecting an appropriate isothermal surface. The change in magnetic
  field across this boundary reveals the likely locations for magnetic
  reconnection, defining the reconnection X-line at the heliosphere. The
  shape of the heliospheric X-line is presented as a function of the
  orientation of the interstellar magnetic field.

---------------------------------------------------------
Title: The Spatial Distribution of Magnetic Reconnection at the
    Heliopause
Authors: Swisdak, M. M.; Opher, M.; Drake, J. F.; Bibi, F. A.
2009AGUFMSH21A1491S    Altcode:
  We propose that magnetic reconnection at the heliopause only occurs
  where the interstellar magnetic field points nearly anti-parallel to
  the heliospheric field. By using large-scale magnetohydrodynamic (MHD)
  simulations of the heliosphere to provide the initial conditions for
  kinetic simulations of heliopause (HP) reconnection we show that the
  energetic pickup ions downstream from the solar wind termination shock
  induce large diamagnetic drifts in the reconnecting plasma and stabilize
  non-anti-parallel reconnection. With this constraint the MHD simulations
  can then show where HP reconnection most likely occurs. We also suggest
  that reconnection triggers the 2-3 kHz radio bursts observed to emanate
  from near the HP. The source locations can then be used to constrain
  the direction and magnitude of the local interstellar magnetic field.

---------------------------------------------------------
Title: Temporal &amp; Spatial Evolution of a Modeled CME Shock and
    Post-shock Compression
Authors: Das, I.; Opher, M.; Evans, R. M.; Gombosi, T. I.
2009AGUFMSH31A1450D    Altcode:
  We studied the temporal and spatial evolution of a modeled Coronal Mass
  Ejection (CME) driven shock and it's post-shock compression. Our goal
  has been to understand how the shock and the post-shock compression, as
  a whole with it's typical geometrical features, evolve over real time
  in different directions. We investigated how θ_Bn (the angle between
  the shock normal and the upstream magnetic field), Vs (shock velocity),
  Ms (Sonic Mach number), Ma (Alfven Mach number) evolve in real time at
  different locations on the shock and the post-shock surface. To do this,
  we used Rankine-Hugoniot (R-H) shock conditions of a 3D MHD shock and
  compared it with the other popular shock defining parameters. We also
  comment on the discrepancies and consequences on our observations. The
  CME has been initiated and then evolved in the lower solar corona with
  the help of Space Weather modeling Framework with a Titov- Demoulin
  (TD) type flux rope.

---------------------------------------------------------
Title: A strong, highly-tilted interstellar magnetic field near the
    Solar System
Authors: Opher, M.; Bibi, F. Alouani; Toth, G.; Richardson, J. D.;
   Izmodenov, V. V.; Gombosi, T. I.
2009Natur.462.1036O    Altcode:
  Magnetic fields play an important (sometimes dominant) role in the
  evolution of gas clouds in the Galaxy, but the strength and orientation
  of the field in the interstellar medium near the heliosphere has
  been poorly constrained. Previous estimates of the field strength
  range from 1.8-2.5μG and the field was thought to be parallel to the
  Galactic plane or inclined by 38-60° (ref. 2) or 60-90° (ref. 3)
  to this plane. These estimates relied either on indirect observational
  inferences or modelling in which the interstellar neutral hydrogen was
  not taken into account. Here we report measurements of the deflection of
  the solar wind plasma flows in the heliosheath to determine the magnetic
  field strength and orientation in the interstellar medium. We find that
  the field strength in the local interstellar medium is 3.7-5.5μG. The
  field is tilted ~20-30° from the interstellar medium flow direction
  (resulting from the peculiar motion of the Sun in the Galaxy) and is
  at an angle of about 30° from the Galactic plane. We conclude that
  the interstellar medium field is turbulent or has a distortion in the
  solar vicinity.

---------------------------------------------------------
Title: Simulations of Winds of Weak-Lined T Tauri Stars: The Magnetic
    Field Geometry and the Influence of the Wind on Giant Planet Migration
Authors: Vidotto, A. A.; Opher, M.; Jatenco-Pereira, V.; Gombosi, T. I.
2009ApJ...703.1734V    Altcode: 2009arXiv0908.2573V
  By means of numerical simulations, we investigate magnetized stellar
  winds of pre-main-sequence stars. In particular, we analyze under which
  circumstances these stars will present elongated magnetic features
  (e.g., helmet streamers, slingshot prominences, etc). We focus on
  weak-lined T Tauri stars, as the presence of the tenuous accretion
  disk is not expected to have strong influence on the structure of
  the stellar wind. We show that the plasma-β parameter (the ratio
  of thermal to magnetic energy densities) is a decisive factor in
  defining the magnetic configuration of the stellar wind. Using initial
  parameters within the observed range for these stars, we show that the
  coronal magnetic field configuration can vary between a dipole-like
  configuration and a configuration with strong collimated polar lines
  and closed streamers at the equator (multicomponent configuration
  for the magnetic field). We show that elongated magnetic features
  will only be present if the plasma-β parameter at the coronal base
  is β<SUB>0</SUB> Lt 1. Using our self-consistent three-dimensional
  magnetohydrodynamics model, we estimate for these stellar winds the
  timescale of planet migration due to drag forces exerted by the stellar
  wind on a hot-Jupiter. In contrast to the findings of Lovelace et
  al., who estimated such timescales using the Weber and Davis model,
  our model suggests that the stellar wind of these multicomponent
  coronae are not expected to have significant influence on hot-Jupiters
  migration. Further simulations are necessary to investigate this result
  under more intense surface magnetic field strengths (~2-3 kG) and higher
  coronal base densities, as well as in a tilted stellar magnetosphere.

---------------------------------------------------------
Title: A Model of Acceleration of Anomalous Cosmic Rays by
    Reconnection in the Heliosheath
Authors: Lazarian, A.; Opher, M.
2009ApJ...703....8L    Altcode: 2009arXiv0905.1120L
  We discuss a model of cosmic ray acceleration that accounts for the
  observations of anomalous cosmic rays (ACRs) by Voyager 1 and 2. The
  model appeals to fast magnetic reconnection rather than shocks as the
  driver of acceleration. The ultimate source of energy is associated
  with magnetic field reversals that occur in the heliosheath. It is
  expected that the magnetic field reversals will occur throughout the
  heliosheath, but especially near the heliopause where the flows slow
  down and diverge with respect to the interstellar wind and also in the
  boundary sector in the heliospheric current sheet. While the first-order
  Fermi acceleration theory within reconnection layers is in its infancy,
  the predictions do not contradict the available data on ACR spectra
  measured by the spacecraft. We argue that the Voyager data are one of
  the first pieces of evidence favoring the acceleration within regions
  of fast magnetic reconnection, which we believe to be a widely spread
  astrophysical process.

---------------------------------------------------------
Title: Surface Alfvén Wave Damping in a Three-Dimensional Simulation
    of the Solar Wind
Authors: Evans, R. M.; Opher, M.; Jatenco-Pereira, V.; Gombosi, T. I.
2009ApJ...703..179E    Altcode: 2009arXiv0908.3146E
  Here we investigate the contribution of surface Alfvén wave damping
  to the heating of the solar wind in minima conditions. These waves
  are present in the regions of strong inhomogeneities in density or
  magnetic field (e.g., the border between open and closed magnetic field
  lines). Using a three-dimensional (3D) magnetohydrodynamics (MHD) model,
  we calculate the surface Alfvén wave damping contribution between 1
  and 4 R <SUB>sun</SUB> (solar radii), the region of interest for both
  acceleration and coronal heating. We consider waves with frequencies
  lower than those that are damped in the chromosphere and on the
  order of those dominating the heliosphere: 3 × 10<SUP>-6</SUP> to
  10<SUP>-1</SUP> Hz. In the region between open and closed field lines,
  within a few R <SUB>sun</SUB> of the surface, no other major source
  of damping has been suggested for the low frequency waves we consider
  here. This work is the first to study surface Alfvén waves in a 3D
  environment without assuming a priori a geometry of field lines or
  magnetic and density profiles. We demonstrate that projection effects
  from the plane of the sky to 3D are significant in the calculation of
  field line expansion. We determine that waves with frequencies &gt;2.8
  ×10<SUP>-4</SUP> Hz are damped between 1 and 4 R <SUB>sun</SUB>. In
  quiet-Sun regions, surface Alfvén waves are damped at further distances
  compared to active regions, thus carrying additional wave energy
  into the corona. We compare the surface Alfvén wave contribution to
  the heating by a variable polytropic index and find it as an order
  of magnitude larger than needed for quiet-Sun regions. For active
  regions, the contribution to the heating is 20%. As it has been argued
  that a variable gamma acts as turbulence, our results indicate that
  surface Alfvén wave damping is comparable to turbulence in the lower
  corona. This damping mechanism should be included self-consistently
  as an energy driver for the wind in global MHD models.

---------------------------------------------------------
Title: Shocks and Magnetized Winds: Learning from the Interaction
    of the Solar System with the Interstellar Medium
Authors: Opher, M.
2009RMxAC..36...60O    Altcode:
  Through the interaction of the solar system with the interstellar medium
  we can learn about shocks and magnetized winds. Voyager 1 crossed,
  in Dec 2004, the termination shock and is now in the heliosheath. On
  August 30, 2007 Voyager 2 crossed the termination shock, providing us
  for the first time in-situ measurements of the subsonic solar wind in
  the heliosheath. Our recent results indicate that magnetic effects, in
  particular the interstellar magnetic field, are very important in the
  interaction between the solar system and the interstellar medium. We
  summarize here our recent work that shows that the interstellar
  magnetic field affects the symmetry of the heliosphere that can be
  detected by different measurements. We combined radio emission and
  energetic particle streaming measurements from Voyager 1 and 2 with
  extensive state-of-the art 3D MHD modeling, to constrain the direction
  of the local interstellar magnetic field. The orientation derived is
  a plane ≈ 60(°) - 90{°} from the galactic plane. As a result of
  the interstellar magnetic field the solar system is asymmetric being
  pushed in the southern direction.

---------------------------------------------------------
Title: Flows in Inner and Outer Heliosphere
Authors: Opher, Merav
2009shin.confE.124O    Altcode:
  In this work we will summarize our group effort on analyzing flows being
  deflected in the CME-sheats and in the Heliosheath. The subsonic flows
  are immediately sensitive to the magnetic structures ahead. We will
  compare the flows in both the lower corona and the outer heliosphere. We
  will show how they are sensitive to both the magnetic filament in CMEs
  and the interstellar magnetic field in the outer heliosphere case.

---------------------------------------------------------
Title: The Effect of the Very Local Interstellar Magnetic Field and
    Pick-Up Ions on Energetic Neutral Atom Maps
Authors: Prested, Christina Lee; Opher, M.; Alouani Bibi, F.;
   Schwadron, N.
2009shin.confE..26P    Altcode:
  The Interstellar Boundary Explorer (IBEX) recently completed its first
  all-sky energetic neutral atom (ENA) map. This map details the intensity
  of 0.01-6 keV ENAs, which carry with them the signature of the plasma
  from the edge of the solar system, where the solar wind and the very
  local interstellar medium (VLISM) collide. While both the parameters
  of the solar wind and VLISM control this boundary region, it has been
  proposed the interstellar magnetic field may be responsible for the
  N-S asymmetry as observed by the Voyager probes. For comparison with
  IBEX's results, we simulate ENA maps for a variety of magnetic field
  orientations at 0.1 keV and find a compass like effect from which
  the VLISM magnetic field direction can be read. <P />We also provide
  an update on the Opher et al. multi-fluid MHD plus neutrals model
  of the heliopshere and the ongoing effort to incorporate a separate
  pick-up ion plasma. Pick-up ions are known to carry upwards of 80%
  of the pressure at the termination shock, but their full effect on ENA
  maps is not yet determined. We offer initial maps from this study and
  suggest further modifications on the assumed pick-up ion distribution
  to explore in the future.

---------------------------------------------------------
Title: Pinning Down the Intensity and Direction of the Local
    Interstellar Magnetic Field
Authors: Opher, M.
2009AIPC.1156..153O    Altcode:
  Through the interaction of the solar system with the interstellar medium
  we can learn about shocks and magnetized winds. Voyager 1 crossed,
  in Dec 2004, the termination shock and is now in the heliosheath. On
  August 30, 2007 Voyager 2 crossed the termination shock, providing us
  for the first time in situ measurements of the subsonic solar wind in
  the heliosheath. Our recent results indicate that magnetic effects,
  in particular the interstellar magnetic field, are very important in
  the interaction between the solar system and the interstellar medium. We
  summarize here our recent work that shows that the interstellar magnetic
  field affects the symmetry of the heliosphere that can be detected
  by different measurements. We combined radio emission and energetic
  particle streaming measurements from Voyager 1 and 2 with extensive
  state-of-the art 3D MHD modeling, to constrain the direction of the
  local interstellar magnetic field. The orientation derived is a plane
  ~60°-90° from the galactic plane. As a result of the interstellar
  magnetic field the solar system is asymmetric, being pushed in the
  southern direction.

---------------------------------------------------------
Title: Reconnection of the sectored heliospheric magnetic field
near the heliopause: a mechanism for the generation of anomalous
    cosmic rays
Authors: Drake, James F.; Opher, M.; Swisdak, M.
2009shin.confE..22D    Altcode:
  The recent observations of the anomalous cosmic ray (ACR) energy
  spectrum as Voyagers 1 and 2 crossed the heliospheric termination
  shock have called into question the conventional shock source of
  these energetic particles. We suggest that the sectored heliospheric
  magnetic field, which results from the flapping of the heliospheric
  current sheet, piles up as it approaches the heliopause, narrowing
  the current sheets that separate the sectors and triggering the onset
  of collisionless magnetic reconnection. Particle-in-cell simulations
  reveal that most of the magnetic energy goes into energetic ions with
  significant but smaller amounts of energy going into electrons. The
  ACR differential energy spectrum takes the form of a power law with
  a spectral index slightly above 1.5. The model has the potential to
  explain several key observations, including the similarities in the
  spectra of different ion species.

---------------------------------------------------------
Title: Surface Alfven Wave Damping in a 3D Simulation of the
    Solar Wind
Authors: Evans, Rebekah Minnel; Opher, Merav; Jatenco-Pereira, Vera;
   Gombosi, Tamas I.
2009shin.confE.131E    Altcode:
  Here we investigate the contribution of surface Alfven wave damping to
  the heating of the solar wind in minima conditions. These waves are
  present in regions of strong inhomogenities in density or magnetic
  field (e. g., the border between open and closed magnetic field
  lines). Using a 3D MHD model, we calculate the surface Alfven wave
  damping contribution between 1-4 Rs (solar radii), the region of
  interest for both acceleration and coronal heating. We consider waves
  with frequencies lower than those that are damped in the chromosphere
  and on the order of those dominating the heliosphere. This work is
  the first to study surface Alfven wave damping in a 3D environment
  without assuming a priori a geometry of field lines or magnetic and
  density profiles. We demonstrate that projection effects from the
  plane of the sky to 3D are significant in the calculation of field
  line expansion. We determine that waves with frequencies &gt;2.8 -
  10^;ˆ’4 Hz are damped between 1-4 Rs. In quiet sun regions, surface
  Alfven waves are damped at further distances compared to active regions,
  thus carrying additional wave energy into the corona. We compare the
  wave contribution to the heating by a variable polytropic index and
  find that it is the same order. As it has been argued that a variable
  gamma acts as turbulence, our results indicate that surface Alfven
  wave damping is comparable to turbulence in the lower corona. This
  damping mechanism should be included self consistently as an energy
  driver for the wind in global MHD models.

---------------------------------------------------------
Title: Multiscale Modeling of Reconnection: Effects on CME Dynamics
Authors: Evans, Rebekah Minnel; Kuznetsova, Maria M.; Opher, Merav;
   Toth, Gabor; Gombosi, Tamas I.
2009shin.confE.189E    Altcode:
  Magnetic reconnection is believed to play a crucial role in
  the initiation and liftoff of a CME, and could continue during
  propagation. However, the best tool to study these events - advanced
  global MHD models - operates in the fluid regime and therefore is
  limited to unphysical numerical and/or ad hoc anomalous reconnection
  terms. Recently, efforts to include kinetic reconnection effects in a
  global MHD code were successfully implemented into the BATS-R-US model
  for the magnetotail. By applying the same techniques used in multiscale
  modeling of magnetospheric reconnection, we simulate for the first time
  the dissipation of magnetic energy of a CME as it propagates through
  the interplanetary medium and the feedback on the background solar
  wind. We initiate the CME using a modified Titov-Demoulin flux rope
  with the Space Weather Modeling Framework and determine the effects
  of the nongyrotropic corrections on the evolution out to 3Rsun.

---------------------------------------------------------
Title: Three-dimensional Numerical Simulations of Magnetized Winds
    of Solar-like Stars
Authors: Vidotto, A. A.; Opher, M.; Jatenco-Pereira, V.; Gombosi, T. I.
2009ApJ...699..441V    Altcode: 2009arXiv0904.4398V
  By means of self-consistent three-dimensional magnetohydrodynamics (MHD)
  numerical simulations, we analyze magnetized solar-like stellar winds
  and their dependence on the plasma-β parameter (the ratio between
  thermal and magnetic energy densities). This is the first study to
  perform such analysis solving the fully ideal three-dimensional MHD
  equations. We adopt in our simulations a heating parameter described by
  γ, which is responsible for the thermal acceleration of the wind. We
  analyze winds with polar magnetic field intensities ranging from 1
  to 20 G. We show that the wind structure presents characteristics
  that are similar to the solar coronal wind. The steady-state magnetic
  field topology for all cases is similar, presenting a configuration of
  helmet streamer-type, with zones of closed field lines and open field
  lines coexisting. Higher magnetic field intensities lead to faster and
  hotter winds. For the maximum magnetic intensity simulated of 20 G and
  solar coronal base density, the wind velocity reaches values of ~1000
  km s<SUP>-1</SUP> at r ~ 20r <SUB>0</SUB> and a maximum temperature
  of ~6 × 10<SUP>6</SUP> K at r ~ 6r <SUB>0</SUB>. The increase of
  the field intensity generates a larger "dead zone" in the wind, i.e.,
  the closed loops that inhibit matter to escape from latitudes lower
  than ~45° extend farther away from the star. The Lorentz force leads
  naturally to a latitude-dependent wind. We show that by increasing
  the density and maintaining B <SUB>0</SUB> = 20 G the system recover
  back to slower and cooler winds. For a fixed γ, we show that the key
  parameter in determining the wind velocity profile is the β-parameter
  at the coronal base. Therefore, there is a group of magnetized flows
  that would present the same terminal velocity despite its thermal
  and magnetic energy densities, as long as the plasma-β parameter
  is the same. This degeneracy, however, can be removed if we compare
  other physical parameters of the wind, such as the mass-loss rate. We
  analyze the influence of γ in our results and we show that it is also
  important in determining the wind structure.

---------------------------------------------------------
Title: Numerical simulations of magnetized winds of solar-like stars
Authors: Vidotto, Aline A.; Opher, M.; Jatenco-Pereira, V.; Gombosi,
   T. I.
2009IAUS..259..415V    Altcode: 2009arXiv0901.1118V
  We investigate magnetized solar-like stellar winds by means of
  self-consistent three-dimensional (3D) magnetohydrodynamics (MHD)
  numerical simulations. We analyze winds with different magnetic
  field intensities and densities as to explore the dependence on the
  plasma-β parameter. By solving the fully ideal 3D MHD equations,
  we show that the plasma-β parameter is the crucial parameter in the
  configuration of the steady-state wind. Therefore, there is a group of
  magnetized flows that would present the same terminal velocity despite
  of its thermal and magnetic energy densities, as long as the plasma-β
  parameter is the same.

---------------------------------------------------------
Title: Properties and Selected Implications of Magnetic Turbulence
    for Interstellar Medium, Local Bubble and Solar Wind
Authors: Lazarian, A.; Beresnyak, A.; Yan, H.; Opher, M.; Liu, Y.
2009SSRv..143..387L    Altcode: 2008SSRv..tmp..172L; 2008arXiv0811.0826L
  Astrophysical fluids, including interstellar and interplanetary
  medium, are magnetized and turbulent. Their appearance, evolution,
  and overall properties are determined by the magnetic turbulence
  that stirs it. We argue that examining magnetic turbulence at a
  fundamental level is vital to understanding many processes. A point
  that frequently escapes the attention of researchers is that magnetic
  turbulence cannot be confidently understood only using “brute
  force” numerical approaches. In this review we illustrate this point
  on a number of examples, including intermittent heating of plasma by
  turbulence, interactions of turbulence with cosmic rays and effects
  of turbulence on the rate of magnetic reconnection. We show that the
  properties of magnetic turbulence may vary considerably in various
  environments, e.g. imbalanced (or cross-helical) turbulence in solar
  wind differs from balanced turbulence and both of these differ from
  turbulence in partially ionized gas. Appealing for the necessity of
  more observational data on magnetic fields, we discuss a possibility
  of studying interplanetary turbulence using alignment of Sodium atoms
  in the tail of comets.

---------------------------------------------------------
Title: The Dynamic Heliosphere: Outstanding Issues. Report of Working
    Groups 4 and 6
Authors: Florinski, V.; Balogh, A.; Jokipii, J. R.; McComas, D. J.;
   Opher, M.; Pogorelov, N. V.; Richardson, J. D.; Stone, E. C.; Wood,
   B. E.
2009SSRv..143...57F    Altcode:
  Properties of the heliospheric interface, a complex product of an
  interaction between charged and neutral particles and magnetic fields
  in the heliosphere and surrounding Circumheliospheric Medium, are
  far from being fully understood. Recent Voyager spacecraft encounters
  with the termination shock and their observations in the heliosheath
  revealed multiple energetic particle populations and noticeable
  spatial asymmetries not accounted for by the classic theories. Some
  of the challenges still facing space physicists include the origin
  of anomalous cosmic rays, particle acceleration downstream of the
  termination shock, the role of interstellar magnetic fields in producing
  the global asymmetry of the interface, the influence of charge exchange
  and interstellar neutral atoms on heliospheric plasma flows, and the
  signatures of solar magnetic cycle in the heliosheath. These and other
  outstanding issues are reviewed in this joint report of working groups
  4 and 6.

---------------------------------------------------------
Title: Confronting Observations and Modeling: The Role of the
    Interstellar Magnetic Field in Voyager 1 and 2 Asymmetries
Authors: Opher, M.; Richardson, J. D.; Toth, G.; Gombosi, T. I.
2009SSRv..143...43O    Altcode: 2008SSRv..tmp..178O
  Magnetic effects are ubiquitous and known to be crucial in space physics
  and astrophysical media. We have now the opportunity to probe these
  effects in the outer heliosphere with the two spacecraft Voyager 1
  and 2. Voyager 1 crossed, in December 2004, the termination shock and
  is now in the heliosheath. On August 30, 2007 Voyager 2 crossed the
  termination shock, providing us for the first time in-situ measurements
  of the subsonic solar wind in the heliosheath. With the recent in-situ
  data from Voyager 1 and 2 the numerical models are forced to confront
  their models with observational data. Our recent results indicate
  that magnetic effects, in particular the interstellar magnetic field,
  are very important in the interaction between the solar system and
  the interstellar medium. We summarize here our recent work that
  shows that the interstellar magnetic field affects the symmetry of
  the heliosphere that can be detected by different measurements. We
  combined radio emission and energetic particle streaming measurements
  from Voyager 1 and 2 with extensive state-of-the art 3D MHD modeling, to
  constrain the direction of the local interstellar magnetic field. The
  orientation derived is a plane ∼60°-90° from the galactic
  plane. This indicates that the field orientation differs from that
  of a larger scale interstellar magnetic field, thought to parallel
  the galactic plane. Although it may take 7-12 years for Voyager 2 to
  leave the heliosheath and enter the pristine interstellar medium,
  the subsonic flows are immediately sensitive to the shape of the
  heliopause. The flows measured by Voyager 2 in the heliosheath indicate
  that the heliopause is being distorted by local interstellar magnetic
  field with the same orientation as derived previously. As a result of
  the interstellar magnetic field the solar system is asymmetric being
  pushed in the southern direction. The presence of hydrogen atoms tend
  to symmetrize the solutions. We show that with a strong interstellar
  magnetic field with our most current model that includes hydrogen atoms,
  the asymmetries are recovered. It remains a challenge for future works
  with a more complete model, to explain all the observed asymmetries
  by V1 and V2. We comment on these results and implications of other
  factors not included in our present model.

---------------------------------------------------------
Title: The Dynamic Heliosphere: Outstanding Issues
Authors: Florinski, V.; Balogh, A.; Jokipii, J. R.; McComas, D. J.;
   Opher, M.; Pogorelov, N. V.; Richardson, J. D.; Stone, E. C.; Wood,
   B. E.
2009fohl.book...57F    Altcode:
  Properties of the heliospheric interface, a complex product of an
  interaction between charged and neutral particles and magnetic fields
  in the heliosphere and surrounding Circumheliospheric Medium, are
  far from being fully understood. Recent Voyager spacecraft encounters
  with the termination shock and their observations in the heliosheath
  revealed multiple energetic particle populations and noticeable
  spatial asymmetries not accounted for by the classic theories. Some
  of the challenges still facing space physicists include the origin
  of anomalous cosmic rays, particle acceleration downstream of the
  termination shock, the role of interstellar magnetic fields in producing
  the global asymmetry of the interface, the influence of charge exchange
  and interstellar neutral atoms on heliospheric plasma flows, and the
  signatures of solar magnetic cycle in the heliosheath. These and other
  outstanding issues are reviewed in this joint report of working groups
  4 and 6.

---------------------------------------------------------
Title: Properties and Selected Implications of Magnetic Turbulence
    for Interstellar Medium, Local Bubble and Solar Wind
Authors: Lazarian, A.; Beresnyak, A.; Yan, H.; Opher, M.; Liu, Y.
2009fohl.book..387L    Altcode:
  Astrophysical fluids, including interstellar and interplanetary
  medium, are magnetized and turbulent. Their appearance, evolution,
  and overall properties are determined by the magnetic turbulence
  that stirs it. We argue that examining magnetic turbulence at a
  fundamental level is vital to understanding many processes. A point
  that frequently escapes the attention of researchers is that magnetic
  turbulence cannot be confidently understood only using "brute force"
  numerical approaches. In this review we illustrate this point on
  a number of examples, including intermittent heating of plasma by
  turbulence, interactions of turbulence with cosmic rays and effects
  of turbulence on the rate of magnetic reconnection. We show that the
  properties of magnetic turbulence may vary considerably in various
  environments, e.g. imbalanced (or cross-helical) turbulence in solar
  wind differs from balanced turbulence and both of these differ from
  turbulence in partially ionized gas. Appealing for the necessity of
  more observational data on magnetic fields, we discuss a possibility
  of studying interplanetary turbulence using alignment of Sodium atoms
  in the tail of comets.

---------------------------------------------------------
Title: Confronting Observations and Modeling: The Role of the
    Interstellar Magnetic Field in Voyager 1 and 2 Asymmetries
Authors: Opher, M.; Richardson, J. D.; Toth, G.; Gombosi, T. I.
2009fohl.book...43O    Altcode:
  Magnetic effects are ubiquitous and known to be crucial in space physics
  and astrophysical media. We have now the opportunity to probe these
  effects in the outer heliosphere with the two spacecraft Voyager 1
  and 2. Voyager 1 crossed, in December 2004, the termination shock and
  is now in the heliosheath. On August 30, 2007 Voyager 2 crossed the
  termination shock, providing us for the first time in-situ measurements
  of the subsonic solar wind in the heliosheath. With the recent in-situ
  data from Voyager 1 and 2 the numerical models are forced to confront
  their models with observational data. Our recent results indicate
  that magnetic effects, in particular the interstellar magnetic field,
  are very important in the interaction between the solar system and
  the interstellar medium. We summarize here our recent work that
  shows that the interstellar magnetic field affects the symmetry of
  the heliosphere that can be detected by different measurements. We
  combined radio emission and energetic particle streaming measurements
  from Voyager 1 and 2 with extensive state-of-the art 3D MHD modeling, to
  constrain the direction of the local interstellar magnetic field. The
  orientation derived is a plane ∼60°-90° from the galactic
  plane. This indicates that the field orientation differs from that
  of a larger scale interstellar magnetic field, thought to parallel
  the galactic plane. Although it may take 7-12 years for Voyager 2 to
  leave the heliosheath and enter the pristine interstellar medium,
  the subsonic flows are immediately sensitive to the shape of the
  heliopause. The flows measured by Voyager 2 in the heliosheath indicate
  that the heliopause is being distorted by local interstellar magnetic
  field with the same orientation as derived previously. As a result of
  the interstellar magnetic field the solar system is asymmetric being
  pushed in the southern direction. The presence of hydrogen atoms tend
  to symmetrize the solutions. We show that with a strong interstellar
  magnetic field with our most current model that includes hydrogen atoms,
  the asymmetries are recovered. It remains a challenge for future works
  with a more complete model, to explain all the observed asymmetries
  by V1 and V2. We comment on these results and implications of other
  factors not included in our present model.

---------------------------------------------------------
Title: 3D Numerical Simulations Of Magnetized Winds Of Solar-Like
    Stars
Authors: Vidotto, A. A.; Opher, M.; Jatenco-Pereira, V.; Gombosi, T. I.
2008AGUFMSH21A1590V    Altcode:
  By means of self-consistent three-dimensional (3D) magnetohydrodynamics
  (MHD) numerical simulations, we analyze magnetized solar-like stellar
  winds and their dependence on the plasma-β parameter (the ratio between
  thermal and magnetic energy densities). This is the first study to
  perform such analysis solving the fully ideal 3D MHD equations. We
  analyze winds with polar magnetic field intensities ranging from 1
  to 20~G. We show that the wind structure presents characteristics
  that are similar to the solar coronal wind. The steady-state magnetic
  field topology for all cases is similar, presenting a configuration of
  helmet streamer-type, with zones of closed field lines and open field
  lines coexisting. Higher magnetic field intensities lead to faster
  and hotter winds. For the maximum magnetic intensity simulated of
  20~G, the wind velocity reaches values of ~ 1000 km~s-1 at r ~ 20~r0
  and a maximum temperature of ~ 6 × 106~K at r~ 6~r0. The increase
  of the field intensity generates a larger "dead zone" in the wind,
  i. e., the closed loops that inhibit matter to escape from latitudes
  lower than ~ 45° extend farther away from the star. The Lorentz
  force leads naturally to a latitude-dependent wind. We show that by
  increasing the density, the system recover back to slower and cooler
  winds. The key parameter in determining the wind velocity profile is
  the β-parameter. Therefore, there is a group of magnetized flows that
  would present the same terminal velocity despite of its thermal and
  magnetic energy densities, as long as the plasma-β parameter is the
  same. This degeneracy, however, can be removed if we compare other
  physical parameters of the wind, such as the mass-loss rate.

---------------------------------------------------------
Title: Presence Of A Reverse Shock In The Evolution Of A CME In The
    Lower Solar Corona
Authors: Das, I.; Opher, M.
2008AGUFMSH13B1546D    Altcode:
  We study the birth and the evolution of a reverse shock in the evolution
  of a CME in the lower solar corona. We study the evolution of the CME
  with Space Weather Modeling Framework (SWMF). To initiate the CME, we
  inserted a Titov-Demoulin (TD) flux rope in an active region of the
  Sun with magnetic field based on the MDI data for the solar surface
  during Carrington rotation 1922. The CME advances on the top of a
  background solar wind created with the help of Wang-Sheeley-Arge (WSA)
  model. We'd explore the signature and characteristics of the reverse
  shock as the CME evolves through the lower corona. We also discuss
  it's implications on the acceleration of particles.

---------------------------------------------------------
Title: Comparison of MHD Simulations of CME Evolution and Structure
    with Coronagraph Observations
Authors: Manchester, W. B.; Vourlidas, A.; Jai, Y.; Lugaz, N.; Roussev,
   I.; Gombosi, T.; Opher, M.
2008AGUFMSH11A..07M    Altcode:
  Coronal mass ejections (CMEs) expel significant amounts of plasma into
  interplanetary space producing large-scale variations in density that
  are manifest in coronagraph images. A limitation of these images is
  that they present two-dimensional projections of three-dimensional
  structures that are challenging to interpret. The circumstances are
  even more complex when CMEs are observed at large elongation and
  the location of preferential scattering is significantly curved. To
  address the interpretation of such coronagraph images, we examine
  the Thomson-scattered white-light appearance of 3D MHD simulations
  of CMEs to identify and reproduce features observed by LASCO and
  SECCHI coronagraphs. We find close quantitative comparison with
  LASCO observations and produce shapes at large elongations as seen
  by SECCHI. We find evidence of shock propagation, magnetic clouds,
  CME pancaking, and complex time evolution as CMEs propagate at large
  elongation past the Thomson sphere. A key point is to determine how the
  3-D structure of CMEs is affected by propagation through a structured
  solar wind.

---------------------------------------------------------
Title: Signatures of Two Distinct Initiation Mechanisms in the
    Evolution of CMEs in the Lower Corona.
Authors: de Souza Costa, C. L.; Opher, M.; Alves, M. V.; Liu, Y. C.;
   Manchester, W. B.; Gombosi, T. I.
2008AGUFMSH23B1636D    Altcode:
  We present a comparison of a three-dimensional (3D) simulation of
  coronal mass ejections (CMEs), in the lower corona, generated with two
  different initiation mechanisms presented in the literature: Gibson
  &amp; Low (1998) (as GL98 hereafter) and Titov &amp; Démoulin (1999)
  (as TD99 hereafter). The simulations are performed using the Space
  Weather Modeling Framework (SWMF) during the solar minimum (CR1922). Our
  goal is to understand how the initial magnetic configuration of a CME
  affects its evolution through the lower corona, until 6R⊙. We found
  that both CME-driven shocks are quasi-parallel at the nose and that
  GL98 presents a higher shock acceleration (~150 m/ s2 versus ~100 m/
  s2) and a higher Mach number, indicating it would accelerate particles
  more efficiently. Both CMEs also presented a post-shock compression for
  R&gt;3R⊙, being slightly larger in the case of TD99. They presented
  also a similar sheath width that increases while propagating away
  from the Sun (larger in GL98 case). We also found that in GL98 case
  the CME is driven by a combination of magnetic and thermal pressure,
  while in TD99 case the thermal pressure dominates its evolution. One of
  the reasons why GL98 presents higher force values, is probably related
  to the fact that its sheath mass is ~20% larger than for TD99. This
  paper intends to serve as a prototype for future comparisons of CME
  evolution, in the lower corona.

---------------------------------------------------------
Title: The Effects of Pickup Ions on Magnetic Reconnection at the
    Heliopause
Authors: Swisdak, M.; Opher, M.; Drake, J. F.
2008AGUFMSH21B1610S    Altcode:
  Recent observations by the Voyager 2 spacecraft after crossing the
  termination shock suggest that interstellar pickup ions account for
  most of the plasma energy downstream from the heliopause. This implies
  that the plasma beta (the ratio of the thermal to magnetic pressure)
  is significantly larger than unity and that strong gradients in the
  temperature exist at the heliopause. Previous work has shown that for
  similar conditions at the Earth's magnetopause the diamagnetic drift
  of X-lines stabilizes magnetic reconnection unless the reconnecting
  fields are nearly anti-parallel. We explore the heliospheric case with
  a combination of MHD simulations of the heliosphere and PIC simulations
  of the region near the X-line and make predictions for the Voyager
  crossings of the heliopause.

---------------------------------------------------------
Title: Balancing Act: The Role of The Interstellar Magnetic Field
    and Neutral H in Voyager 1 and 2 Asymmetries
Authors: Opher, M.; Stone, E. C.; Toth, G.; Izmodenov, V.; Alexashov,
   V.; Gombosi, T. I.
2008AGUFMSH14A..07O    Altcode:
  We present results from recently developed 5 fluid MHD model (4
  neutral fluids and 1 ionized fluid). We present a benchmark comparison
  between our model and the kinetic Moscow model for the case of strong
  interstellar magnetic field, and no interplanetary field. The presence
  of neutral H, as pointed out by previous works, has the effect of
  diminishing the global heliospheric asymmetries. With a stronger
  interstellar field, however, the asymmetries are increased. Results
  of the 5-fluid MHD model have been employed as an starting point for a
  new kinetic-MHD model that combines the BATS-R-US MHD code with the 3D
  Monte- Carlo Moscow code. We present first results of this new coupled
  model. We discuss these results and compare with our previous work
  (Opher et al. 2006, 2007). Our goal is to constrain the orientation
  and intensity of the interstellar magnetic field that can satisfy
  the different constraints from the observed asymmetries (energetic
  particles streaming (east- west); the 10AU differences between V1 and
  V2 crossing; radio emission; and neutral H deflection).

---------------------------------------------------------
Title: Surface Alfven Wave Damping in a 3D Simulation of the
    Solar Wind
Authors: Evans, R. M.; Opher, M.; Jatenco-Pereira, V.; Gombosi, T. I.
2008AGUFMSH51B1600E    Altcode:
  It is known that a source of additional momentum is needed to drive
  the solar wind. Here we investigate the effect of surface Alfvén wave
  damping in solar minima and solar maxima conditions. The surface Alfvén
  wave damping length L depends on the superradial expansion factor S
  of magnetic field lines. We calculate S for Carrington Rotation 1912
  with a steady state solar background generated with the Space Weather
  Modeling Framework, and compare with estimates by Dobrzycka et al. 1999
  using SOHO observations. We estimate the surface Alfvén wave damping
  for active regions, quiet sun, and the border between open and closed
  magnetic field lines. We address how our results can be incorporated
  in a MHD thermally driven-wind model.

---------------------------------------------------------
Title: Effects Non-uniform Flux Transfer and Empirically Based
    Heliosheath Plasma Distributions on Global Maps of Heliospheric
    Energetic Neutral Atoms
Authors: Prested, C.; Schwadron, N.; McComas, D.; Opher, M.; Crew,
   G.; Vanderspek, R.; Maynard, K.; Goodrich, K.; Fuselier, S.; Funsten,
   H.; Janzen, P.; Kucharek, H.; Moebius, E.; Reisenfeld, D.; Peterson,
   L.; Saul, L.
2008AGUFMSH21B1598P    Altcode:
  The launch of the Interstellar Boundary Explorer (IBEX) begins a
  new generation of outer heliospheric science. From its high-altitude
  orbit, the IBEX mission will produce the first all-sky maps of energetic
  neutral atoms (ENAs) created directly from the heliosheath plasma, which
  carries the imprint of the global boundaries of the solar system. Here,
  we explore the importance of key interstellar and solar wind parameters
  to global maps of ENA flux at 1 AU, generated by a combination of
  physical models: a magnetohydrodynamic heliosheath plasma simulation,
  flux-transfer through the heliosphere including non-uniform loss,
  and a full IBEX instrument model. We also discuss the impact of the
  pick-up ion and thermal solar wind distributions as implied by recent
  STEREO and Voyager measurements.

---------------------------------------------------------
Title: Alfvén Profile in the Lower Corona: Implications for Shock
    Formation
Authors: Evans, R. M.; Opher, M.; Manchester, W. B., IV; Gombosi, T. I.
2008ApJ...687.1355E    Altcode:
  Observations of type II radio bursts and energetic electron events
  indicate that shocks can form at 1-3 solar radii and are responsible
  for the GeV nucleon<SUP>-1</SUP> energies observed in ground level
  solar energetic particle (SEP) events. Here we provide the first study
  of the lower corona produced from 10 state-of-the-art models. In
  particular, we look to the Alfvén speed profiles as the criterion
  for shock formation, independent of exciting agent (e.g., flares
  and CMEs). Global magnetohydrodynamic models produce Alfvén speed
  profiles that are in conflict with observations: (1) multiple SEP
  events are observed with a single exciting agent, but most profiles
  are missing the "hump" required to form multiple shocks; and (2) few
  slow CMEs cause large SEP events, but most profiles drop very quickly,
  allowing all slow CMEs to drive strong shocks to form between 1 and
  3 R<SUB>⊙</SUB>. Simplified Alfvén wave-driven wind models have
  steeper profiles, but are still in disagreement with multiple shock
  formation. Only studies that include Alfvén waves with physically
  based damping are in agreement with observations. This implies the
  results of these one-dimensional local studies must be included in
  global models before we can study shock formation in the lower corona.

---------------------------------------------------------
Title: Three-dimensional MHD Simulation of the 2003 October 28
Coronal Mass Ejection: Comparison with LASCO Coronagraph Observations
Authors: Manchester, Ward B., IV; Vourlidas, Angelos; Tóth, Gábor;
   Lugaz, Noé; Roussev, Ilia I.; Sokolov, Igor V.; Gombosi, Tamas I.;
   De Zeeuw, Darren L.; Opher, Merav
2008ApJ...684.1448M    Altcode: 2008arXiv0805.3707M
  We numerically model the coronal mass ejection (CME) event of 2003
  October 28 that erupted from AR 10486 and propagated to Earth in less
  than 20 hr, causing severe geomagnetic storms. The magnetohydrodynamic
  (MHD) model is formulated by first arriving at a steady state corona
  and solar wind employing synoptic magnetograms. We initiate two
  CMEs from the same active region, one approximately a day earlier
  that preconditions the solar wind for the much faster CME on the
  28th. This second CME travels through the corona at a rate of
  over 2500 km s<SUP>-1</SUP>, driving a strong forward shock. We
  clearly identify this shock in an image produced by the Large Angle
  Spectrometric Coronagraph (LASCO) C3 and reproduce the shock and its
  appearance in synthetic white-light images from the simulation. We
  find excellent agreement with both the general morphology and the
  quantitative brightness of the model CME with LASCO observations. These
  results demonstrate that the CME shape is largely determined by its
  interaction with the ambient solar wind and may not be sensitive to the
  initiation process. We then show how the CME would appear as observed
  by wide-angle coronagraphs on board the Solar Terrestrial Relations
  Observatory (STEREO) spacecraft. We find complex time evolution of
  the white-light images as a result of the way in which the density
  structures pass through the Thomson sphere. The simulation is performed
  with the Space Weather Modeling Framework (SWMF).

---------------------------------------------------------
Title: A Simulation of a Coronal Mass Ejection Propagation and Shock
    Evolution in the Lower Solar Corona
Authors: Liu, Y. C. -M.; Opher, M.; Cohen, O.; Liewer, P. C.; Gombosi,
   T. I.
2008ApJ...680..757L    Altcode:
  We present a detailed simulation of the evolution of a moderately slow
  coronal mass ejection (CME; 800 km s<SUP>-1</SUP> at 5 R<SUB>⊙</SUB>,
  where R<SUB>⊙</SUB> is solar radii) in the lower solar corona
  (2-5 R<SUB>⊙</SUB>). The configuration of the Sun's magnetic field
  is based on the MDI data for the solar surface during Carrington
  rotation 1922. The pre-CME background solar wind is generated using
  the Wang-Sheeley-Arge (WSA) model. To initiate a CME, we inserted a
  modified Titov-Demoulin flux rope in an active region near the solar
  equator using the Space Weather Modeling Framework (SWMF). After
  the initiation stage (within 2.5 R<SUB>⊙</SUB>), the CME evolves
  at a nearly constant and slow acceleration of the order of 100 m
  s<SUP>-2</SUP>, which corresponds to an intermediate-acceleration
  CME. Detailed analysis of the pressures shows that the thermal pressure
  accounts for most of the acceleration of the CME. The magnetic pressure
  contributes to the acceleration early in the evolution and becomes
  negligible when the CME moves beyond ~3 R<SUB>⊙</SUB>. We also
  present the evolution of the shock geometry near the nose of the CME,
  which shows that the shock is quasi parallel most of the time.

---------------------------------------------------------
Title: Implications of solar wind suprathermal tails for IBEX ENA
    images of the heliosheath
Authors: Prested, C.; Schwadron, N.; Passuite, J.; Randol, B.; Stuart,
   B.; Crew, G.; Heerikhuisen, J.; Pogorelov, N.; Zank, G.; Opher, M.;
   Allegrini, F.; McComas, D. J.; Reno, M.; Roelof, E.; Fuselier, S.;
   Funsten, H.; Moebius, E.; Saul, L.
2008JGRA..113.6102P    Altcode:
  Decades of interplanetary measurements of the solar wind and other
  space plasmas have established that the suprathermal ion intensity
  distributions (j) are non-Maxwellian and are characterized by
  high-energy power law tails (j ∼ E<SUP>-κ</SUP>). Recent analysis
  by Fisk and Gloeckler of suprathermal ion observations between 1-5 AU
  demonstrates that a particular differential intensity distribution
  function emerges universally between ∼2-10 times the solar wind
  speed with κ ∼ 1.5. This power law tail is particularly apparent
  in downstream distributions beyond reverse shocks associated with
  corotating interaction regions. Similar power law tails have been
  observed in the downstream flow beyond the termination shock by
  the Low Energy Charged Particle instrument on both Voyager 1 and
  Voyager 2. Using kappa distributions with internal energy, density,
  and bulk flow derived from large-scale magnetohydrodynamic models,
  we calculate the simulated flux of energetic neutral atoms (ENAs)
  produced in the heliosheath by charge exchange between solar wind
  protons and interstellar hydrogen. We then produce simulated ENA
  maps of the heliosheath, such as will be measured by the Interstellar
  Boundary Explorer Mission (IBEX). We also estimate the expected signal
  to noise and background ratio for IBEX. The solar wind suprathermal
  tail significantly increases the ENA flux within the IBEX energy
  range, ∼0.01-6 keV, by more than an order of magnitude at the
  highest energies over the estimates using a Maxwellian. It is therefore
  essential to consider suprathermal tails in the interpretation of IBEX
  ENA images and theoretical modeling of the heliospheric termination
  shock.

---------------------------------------------------------
Title: Role of the Interstellar Magnetic Field in the Flows in
    the Heliosheath
Authors: Opher, M.; Stone, E. C.; Richardson, J. C.; Gombosi, T. I.
2008AGUSMSH24A..08O    Altcode:
  Magnetic effects are ubiquitous and known to be crucial in space
  physics and astrophysical media; Space physics is an excellent
  plasma laboratory and provide observational data that add crucial
  constraints to theoretical models. Voyager 1 crossed in Dec 2004,
  the termination shock and is now in the heliosheath. On August 30,
  2007 Voyager 2 crossed the termination shock providing us for the
  first time with in-situ measurements of the subsonic solar wind in
  the heliosheath. In this talk I will review our recent results that
  indicate that magnetic effects, in particular the interstellar magnetic
  field, are very important in the interaction between the solar system
  and the interstellar medium. Recently, combining radio emission and
  energetic particle streaming measurements from Voyager 1 and 2 with
  extensive state-of-the art 3D MHD modeling, we were able to constrain
  the direction of the local interstellar magnetic field. Although might
  take 7-12 years for Voyager 2 to leave the heliosheath and enter the
  pristine interstellar medium, the subsonic flows are immediately
  sensitive to the shape of the heliopause. We show that the flows
  measured by Voyager 2 from days 258-350 indicate that the heliopause
  is being distorted by a local interstellar magnetic field ~ 60°-90°
  from the galactic plane. This confirms our earlier prediction that
  the field orientation in the Local Interstellar Cloud differs that of
  a larger scale interstellar magnetic field, thought to parallel the
  galactic plane. As a result of the interstellar magnetic field the
  solar system is asymmetric being pushed in the southern direction.

---------------------------------------------------------
Title: When Magnetized Winds Collide: Role of the Interstellar
    Magnetic Field Shaping the Heliosphere
Authors: Opher, Merav; Stone, Edward; Richardson, John; Toth, Gabor;
   Alexashov, Dmitry; Izmodenov, Vladislav; Gombosi, Tamas
2008cosp...37.2295O    Altcode: 2008cosp.meet.2295O
  Magnetic effects are ubiquitous and known to be crucial in space
  physics and astrophysical media; Space physics is an excellent
  plasma laboratory and provide observational data that add crucial
  constraints to theoretical models. Voyager 1 crossed in Dec 2004,
  the termination shock and is now in the heliosheath. On August 30,
  2007 Voyager 2 crossed the termination shock providing us for the
  first time with in-situ measurements of the subsonic solar wind in
  the heliosheath. In this talk I will review our recent results that
  indicate that magnetic effects, in particular the interstellar magnetic
  field, are very important in the interaction between the solar system
  and the interstellar medium. Recently, combining radio emission and
  energetic particle streaming measurements from Voyager 1 and 2 with
  extensive state-of-the art 3D MHD modeling, we were able to constrain
  the direction of the local interstellar magnetic field. Although might
  take 7-12 years for Voyager 2 to leave the heliosheath and enter the
  pristine interstellar medium, the subsonic flows are immediately
  sensitive to the shape of the heliopause. We show that the flows
  measured by Voyager 2 from days 258-350 indicate that the heliopause
  is being distorted by a local interstellar magnetic field 60° -90°
  from the galactic plane. This confirms our earlier prediction that
  the field orientation in the Local Interstellar Cloud differs that of
  a larger scale interstellar magnetic field, thought to parallel the
  galactic plane. As a result of the interstellar magnetic field the
  solar system is asymmetric being pushed in the southern direction. I
  will comment on these results and present preliminary results of the
  effect of H neutrals on our previous MHD results.

---------------------------------------------------------
Title: Effects of the helisopheric and interstellar magnetic field
    on the heliospheric interface
Authors: Alexashov, Dmitry; Izmodenov, Vladislav; Malama, Yury;
   Opher, Merav
2008cosp...37...56A    Altcode: 2008cosp.meet...56A
  First results of the numerical simulations of the heliospheric interface
  that take into account both the interstellar hydrogen atoms and the
  heliospheric and interstellar magnetic fields are presented. The
  calculations are based on the newly created stationary 3D kinetic-MHD
  model that treates the H atoms kinetically. The effects of the magnetic
  fields on the shapes and positions of the strong plasma discontinuties
  are clearly shown. The influence of the interstellar magnetic field
  direction and amplitude is studied. The imprints of the interstellar
  and heliospheric magnetic field on distribution of interstellar H
  atoms inside the heliosphere are explored.

---------------------------------------------------------
Title: The Interstellar Boundary Explorer Instrument Models and
    Predicted ENA Count Rates
Authors: Prested, C.; Schwadron, N.; Passuite, J.; Randol, B.; Stuart,
   B.; Heerikhuisen, J.; Opher, M.; Allegrini, F.; Steve, F.; Funsten,
   H.; Moebius, E.
2007AGUFMSH14A1688P    Altcode:
  The upcoming launch of the Interstellar Boundary Explorer (IBEX)
  promises a unique data set of heliospheric energetic neutral atoms
  (ENAs), rich with information about the global dynamics of the
  termination shock and heliosheath. We have developed a suite of tools
  to predict synthetic ENA flux from the internal energy, density, and
  bulk flow derived from large-scale magnetohydrodynamic simulations of
  the heliosheath, creating a visualization framework for ENA flux maps
  as well as making predictions for the IBEX mission. In the future
  these tools will be critical for interpreting the implications of
  IBEX observations. The impact of the ion distribution function is
  also explored in the context of ENA flux maps. Studies from ACE,
  WIND, and Ulysses have shown the solar wind ion population has a power
  law tail in suprathermal velocities between 2-10 times the solar wind
  speed. This solar wind characteristic is found to increase the predicted
  flux by more than an order of magnitude at the highest IBEX energies,
  with less but considerable impact at lower energies.

---------------------------------------------------------
Title: Numerical Simulation of a Coronal Mass Ejection in the Lower
Corona: Comparison of Two Initiation Models
Authors: Loesch, C.; Opher, M.; Liu, Y.; Manchester, W. B., IV;
   Gombosi, T. I.; Alves, M. V.
2007AGUFMSH32A0783L    Altcode:
  Coronal mass ejections (CME), eruptions of plasma and embedded magnetic
  field from the Sun's corona into interplanetary space, are the most
  energetic events on the Sun. The exact processes involved in the release
  of CMEs are not known. In order to understand them and how they affect
  the environment around Earth we need to comprehend their eruption,
  development and propagation through the interplanetary space. In this
  work, we present a simulation of a CME event occurred during the solar
  minimum. This simulation was performed using the Space Weather Modeling
  Framework (SWMF). Within this model, after generating a global steady
  state of the solar corona, for CR1922, we drive a CME to erupt using
  two different initiation models presented in the literature; Gibson
  and Low (1998) and Titov and Démoulin (1999). The ejections, that
  were followed up to distances of 10 R\sun, reached maximum speeds of
  800-1000 km s-1. We discuss these two CME initiation models establishing
  a comparative analysis of their characteristics and how the initiation
  process changes the evolution of a simulated CME.

---------------------------------------------------------
Title: Modeling STEREO White-Light Observations of CMEs with 3D
    MHD Simulations
Authors: Manchester, M. B.; Vourlidas, A.; Toth, G.; Lugaz, N.;
   Sokolov, I.; Gombosi, T.; de Zeeuw, D.; Opher, M.
2007AGUFMSH32A0785M    Altcode:
  We model the Thomson-scattered white-light appearance of a variety of
  3D MHD models of CMEs during solar minimum to reproduce large-scale
  features of SECCHI observations. We create a gallery of expected CME
  shapes at large elongations as seen by SECCHI. We examine evidence of
  shock propagation, magnetic clouds, CME pancaking, and complex time
  evolution as CMEs propagate at large elongation past the Thomson
  sphere. A key point is to determine how the structure of CMEs and
  CME-driven shocks are affected by interaction with the ambient solar
  wind. MHD models are performed with BATSRUS and SWMF, and formulated
  by first arriving at a steady state corona and solar wind employing
  synoptic magnetograms. We initiate CMEs from active regions low in
  the corona with magnetic flux ropes.

---------------------------------------------------------
Title: The Orientation of the Local Interstellar Magnetic Field and
Induced Asymmetries of the Heliosphere: Neutrals-MHD model
Authors: Opher, M.; Stone, E. C.; Izmodenov, V.; Malama, Y.; Alexashov,
   D.; Toth, G.; Gombosi, T.
2007AGUFMSH12B..03O    Altcode:
  We present the results of a 3D Neutral-MHD model of the heliosphere. The
  neutrals are treated in a multi-fluid approach coupled to the ionized
  component by charge exchange. Comparisons are made with previous studies
  that showed that the local interstellar magnetic field introduces
  asymmetries in the heliosphere that are consistent with Voyager 1 and
  2 observations of radio emissions and energetic particle streaming
  (Opher et al. Science 2007; Opher et al. ApJL 2006). We present,
  additionally, preliminary results of a 3D Kinetic-MHD model. The
  main advantage of this model is a rigorous kinetic description of
  interstellar H atoms, especially at the Bow Shock, Heliopause and
  Termination Shock interfaces. Differences of kinetic and multi-fluid
  approaches are discussed. The new model should provide refined estimates
  of the strength and direction of the local interstellar field and of
  the resulting distortions of the shape of the heliosphere.

---------------------------------------------------------
Title: A simulation of a CME propagation and shock evolution in the
    lower solar corona
Authors: Liu, Y. C.; Opher, M.; Cohen, O.; Gombosi, T. I.
2007AGUFMSH32A0777L    Altcode:
  We present a simulation of the evolution of a CME (~800km/s at 5
  solar radii) in the lower solar corona (until 5 solar radii) using
  Space Weather Modeling Framework (SWMF). The configuration of the
  sun's magnetic field is based on the MDI data on the solar surface
  during Carrington Rotation 1922. The pre-CME background solar wind is
  generated under this boundary condition and Wang-Sheeley-Arge (WSA)
  model. To initiate a CME, we inserted a Titov-Demoulin flux rope in an
  active region near the solar equator. The zone along nose of the CME
  is refined to resolve the CME-driven-shock. Our results show that a
  higher density region is followed by a dark cavity behind the shock and
  the higher density region is expanding while propagating away from the
  sun. These features are consistent with the CME observations which shows
  that a bright front followed by a dark area after the shock. After the
  initiation stage, in which the CME has a large acceleration followed
  by a deceleration, the CME demonstrates a nearly constant and slow
  acceleration of the order of 100m/s 2. At 5 solar radii, the CME has a
  speed of 800km/s. Although CME is accelerating, the Mach number of the
  shock is decreasing because the Alfven speed upstream of the shock is
  increasing. Detailed analysis of the pressures on the CME shows that
  the thermal pressure account for most of the acceleration of the CME
  and the magnetic pressure contribute to the acceleration at an early
  time but it becomes negligible when the CME moves further away from
  the sun. We also present the evolution of shock geometry near the nose
  of the CME and find that the shock is nearly perpendicular. Further
  investigation of the dependency in latitude of the shock and their
  effects on particle acceleration are required in a future work.

---------------------------------------------------------
Title: Alfven Profile in the Lower Corona: Implications for Shock
    Formation
Authors: Evans, R. M.; Opher, M.; Manchester, W. B.; Velli, M.;
   Gombosi, T. I.
2007AGUFMSH21A0286E    Altcode:
  Recent events (e.g. Tylka et al. 2005) indicate that CME-driven shocks
  can form at 1-3 solar radii and are responsible for the GeV/nucleon
  energies observed in some ground level solar energetic particle
  events. The formation of shocks depends crucially on the background
  solar wind environment, in particular on the profile of the background
  Alfvén speed in the corona. Significant strides have been made in
  the effort to develop realistic models of CME events; however, there
  is no consensus as to the profile of the Alfvén speed in the lower
  corona. Here we provide an overview of ten state-of-the-art models,
  which includes various methods to model magnetic field and density,
  as well as different strategies for accelerating the solar wind. We
  present the Alfvén speed profile for each model in the lower corona. We
  find that the "valley" and "hump" structures anticipated by Mann et
  al. (2003) are sometimes present, but in some models the Alfvén
  profiles drop off quickly. We discuss the implications of these
  profiles, such as whether it will allow a shock to form, dissipate,
  and form again (i.e. multiple shocks). Our study indicates that it is
  crucial to establish the Alfvén speed as a function of height before
  determining if shocks can form in the lower corona.

---------------------------------------------------------
Title: The Orientation of the Local Interstellar Magnetic Field and
    Induced Asymmetries on the Heliosphere
Authors: Opher, M.; Stone, E. C.; Gombosi, T.
2007AGUSMSH43A..07O    Altcode:
  We combine radio emission and energetic particle streaming measurements
  with extensive 3D MHD computer simulations of magnetic field draping
  over the heliopause to obtain information on the inclination angle of
  the local interstellar magnetic field. The orientation of the local
  interstellar magnetic field introduces asymmetries in the heliosphere
  that affect the location of radio emission and the streaming direction
  of ions from the termination shock of the solar wind. In this talk
  we discuss the orientation of the plane of the local interstellar
  field and the global asymmetries induced in the heliosphere and in
  the heliosheath.

---------------------------------------------------------
Title: Test-particle Orbit Simulations in Fields from a Realistic
    3D MHD Simulation
Authors: Decker, R. B.; Opher, M.; Hill, M. E.
2007AGUSMSH51A..02D    Altcode:
  Models designed to explore the global structure of the heliosphere have
  become increasing sophisticated. Incentives to increase and to further
  explore the predictive capabilities of such models include the entry
  of the Voyager spacecraft into the foreshock region of the termination
  shock (TS), Voyager 1 in mid-2002 and Voyager 2 in late 2004, and the
  crossing of the TS and passage into the heliosheath (HSH) of Voyager
  1 in 2004 day 351. Using the electric and magnetic fields generated by
  a MHD model of a 3D, asymmetric heliosphere [Opher et al., Ap. J. L.,
  640, 2006], we have developed full-particle and adiabatic-orbit codes
  to simulate the motion of test particles in the solar wind, TS, and
  HSH environments. The full-particle orbits are necessary to investigate
  energetic ion (e.g., anomalous and galactic cosmic ray) motion at the TS
  and within the heliospheric current sheet that is included in the MHD
  model. Adiabatic orbits are used to study particle motion in the much
  larger volume of the HSH where the non-homogeneous model fields produce
  complex guiding center motions, including mirroring in local field
  compressions. We will present results from these orbit computations,
  which are intended to provide an initial, albeit simplified, look at
  the propagation of high-energy charged particles, in the scatter-free
  limit, in the best model of the TS/HSH field configurations currently
  available. We will also display drift paths of high-energy ions in the
  HSH fields using the guiding center drift equations that are applicable
  in the limit of diffusive propagation.

---------------------------------------------------------
Title: The Orientation of the Local Interstellar Magnetic Field
Authors: Opher, M.; Stone, E. C.; Gombosi, T. I.
2007Sci...316..875O    Altcode: 2007arXiv0705.1841O
  The orientation of the local interstellar magnetic field introduces
  asymmetries in the heliosphere that affect the location of heliospheric
  radio emissions and the streaming direction of ions from the termination
  shock of the solar wind. We combined observations of radio emissions
  and energetic particle streaming with extensive three-dimensional
  magnetohydrodynamic computer simulations of magnetic field draping
  over the heliopause to show that the plane of the local interstellar
  field is ~60° to 90° from the galactic plane. This finding suggests
  that the field orientation in the Local Interstellar Cloud differs
  from that of a larger-scale interstellar magnetic field thought to
  parallel the galactic plane.

---------------------------------------------------------
Title: Constraining the Local Interstellar Magnetic Field Direction
    from Source Location of the Heliospheric 2-3kHz Radio Emissions
Authors: Opher, M.; Stone, E. C.; Gombosi, T. I.
2006AGUFMSH53B1488O    Altcode:
  Using an MHD model, we have investigated the recent suggestion by
  Gurnett et al. (2006) that the sources of the heliospheric 2-3~kHz radio
  detected by Voyager 1 and 2 should be located where the interstellar
  magnetic field is tangential to the surface of the shock that excites
  the plasma. Because the field is draped over the heliopause surface that
  is distorted by the field, we ran models with different interstellar
  field directions. The best agreement is obtained for an interstellar
  magnetic field parallel to the plane perpendicular to the galactic
  plane (PPG) as suggested by Gurnett et al. and having a small angle
  with respect to the velocity of the interstellar wind. The PPG plane
  is similar to the plane suggested by Lallement et al. 2005 (differing
  by 16°) that Opher et al. (2006) showed to be consistent with the
  streaming directions of energetic particles from the termination shock
  as observed by Voyager 1 and 2. We suggest the radio source locations
  can be used to further constraint a more complete model.

---------------------------------------------------------
Title: Global asymmetry of the heliosphere
Authors: Opher, Merav; Stone, Edward C.; Liewer, Paulett C.; Gombosi,
   Tamas
2006AIPC..858...45O    Altcode: 2006astro.ph..6324O
  Opher et al. showed that an interstellar magnetic field parallel to
  the plane defined by the deflection of interstellar hydrogen atoms can
  produce a north/south asymmetry in the distortion of the solar wind
  termination shock. This distortion is consistent with Voyager 1 and
  Voyager 2 observations of the direction of field-aligned streaming
  of the termination shock particles upstream the shock. The model
  also indicates that such a distortion will result in a significant
  north/south asymmetry in the distance to the shock and the thickness
  of heliosheath. The two Voyager spacecraft should reveal the nature
  and degree of the asymmetry in the termination shock and heliosheath.

---------------------------------------------------------
Title: Tearing and Kelvin-Helmholtz instabilities in the heliospheric
    plasma
Authors: Bettarini, L.; Landi, S.; Rappazzo, F. A.; Velli, M.;
   Opher, M.
2006A&A...452..321B    Altcode:
  We used 2.5D simulations to analyze the magnetohydrodynamic
  instabilities arising from an initial equilibrium configuration
  consisting of a plasma jet or wake in the presence of a magnetic
  field with strong transverse gradients, such as those arising in the
  solar wind. Our analysis extends previous results by considering both
  a force-free equilibrium and a pressure-balance condition for a jet
  in a plasma sheet, along with arbitrary angles between the magnetic
  field and velocity field. In the force-free case, the jet/wake does
  not contain a neutral sheet but the field rotates through the flow to
  invert its polarity. The presence of a magnetic field component aligned
  with the jet/wake destroys the symmetric nature of the fastest growing
  modes, leading to asymmetrical wake acceleration (or, equivalently,
  jet deceleration). In the case of a jet, the instability properties
  depend both on the magnetic field and flow gradients, as well as on
  the length of the jet. The results are applied to the post-termination
  shock jet recently found in 3D global heliospheric simulations, where
  our analysis confirms and explains the stability properties found in
  such simulations.

---------------------------------------------------------
Title: Surprises From The Edge Of The Solar System: Voyager At The
    Final Frontier
Authors: Opher, Merav
2006SPD....37.2301O    Altcode: 2006BAAS...38..250O
  Our solar system presents a unique local example of the interaction
  of a stellar wind and the interstellar medium. As the Sun travels
  through the interstellar medium, it is subject to an interstellar
  wind. The heliosphere is created by the supersonic solar wind that
  abruptly slows, forming a termination shock as it approaches contact
  with the interstellar medium at the heliopause. After 27 years of
  anticipation, in 2004 December 16, Voyager 1, crossed the termination
  shock, at 94AU, and began exploring the heliosheath. The twin Voyager
  spacecraft are probing the northern and southern hemispheres of the
  heliosphere. Voyager 1 is now beyond 98AU, while Voyager 2 is beyond 78
  AU. As Voyager 1 crossed the termination shock, and began exploring the
  heliosheath it became increasingly clear that this previously unexplored
  region is full of surprises. These include the startling absence of
  the anomalous cosmic ray source that had been widely anticipated,
  the unusually slow and even sunward flow of the solar wind in the
  heliosheath, and the unexpected direction of the magnetic field downwind
  of the shock. In mid 2002, Voyager 1 began observing strong energetic
  beams of termination shock particles, streaming outward along the spiral
  magnetic field upstream the shock. This led to the suggestion that
  the termination shock is a blunt structure. Recently we showed that
  an interstellar magnetic field can produce a north/south asymmetry in
  the solar wind termination shock, consistent with Voyager 1 observation
  of the direction of streaming of the particles. These recent surprises
  indicate that a global understanding of the heliosphere is crucial. In
  this talk, I will review the current understanding of the edge the
  solar system, indicate predictions of what Voyager 2 will encounter,
  and describe the directions that research should take to understand
  the global structure of the heliosphere.

---------------------------------------------------------
Title: Effects of a Local Interstellar and Interplanetary Magnetic
    Field on the Heliosheath
Authors: Opher, M.; Stone, E. C.; Liewer, P. C.; Gombosi, T. I.
2006AGUSMSH22A..04O    Altcode:
  In this talk we review some of our recent results showing that that
  an interstellar magnetic field can produce a north/south asymmetry in
  solar wind termination shock. Using Voyager 1 and 2 measurements, we
  suggest that the angle α between the interstellar wind velocity and
  magnetic field is 30 &lt; α &lt; 60°. The distortion of the shock
  is such that termination shock particles could stream outward along
  the spiral interplanetary magnetic field connecting Voyager 1 to the
  shock when the spacecraft was within ~ 2~AU of the shock. The shock
  distortion is larger in the southern hemisphere, and Voyager 2 could
  be connected to the shock when it is within ~ 5~AU of the shock, but
  with particles from the shock streaming inward along the field. Tighter
  constraints on the interstellar magnetic field should be possible when
  Voyager 2 crosses the shock in the next several years. We comment
  additionally on previous work (Opher et al. 2003, 2004) that show
  that the magnetic field shape dramatically the heliosheath flows. We
  indicate future directions of research to probe these effects.

---------------------------------------------------------
Title: The Effects of a Local Interstellar Magnetic Field on Voyager
    1 and 2 Observations
Authors: Opher, Merav; Stone, Edward C.; Liewer, Paulett C.
2006ApJ...640L..71O    Altcode: 2006astro.ph..3318O
  We show that an interstellar magnetic field can produce a
  north-south asymmetry in the solar wind termination shock. Using
  Voyager 1 and 2 measurements, we suggest that the angle α
  between the interstellar wind velocity and the magnetic field is
  30<SUP>deg</SUP>&lt;α&lt;60<SUP>deg</SUP>. The distortion of the shock
  is such that termination shock particles could have streamed outward
  along the spiral interplanetary magnetic field connecting Voyager 1
  to the shock when the spacecraft was within ~2 AU of the shock. The
  shock distortion is larger in the southern hemisphere, and Voyager
  2 could be connected to the shock when it is within ~5 AU of the
  shock, but with particles from the shock streaming inward along the
  field. Tighter constraints on the interstellar magnetic field should
  be possible when Voyager 2 crosses the shock in the next several years.

---------------------------------------------------------
Title: Nonlinear analysis of jet/wake and current sheet interactions
    in the heliospheric plasma
Authors: Bettarini, L.; Landi, S.; Rappazzo, F.; Velli, M.; Opher, M.
2006cosp...36.2383B    Altcode: 2006cosp.meet.2383B
  The interactions between a stream and a current sheet is the starting
  point to understand the dynamics and evolution of complex structures
  in the Heliospheric region We used 2 5D simulations to analyze the
  magnetohydrodynamic instabilities arising from an initial equilibrium
  configuration consisting of a plasma jet or wake in the presence of a
  magnetic field with strong transverse gradients such as those arising
  in the solar wind both close to the Sun and far from it Our analysis
  extends previous results by considering both a force-free equilibrium
  and a pressure-balance condition for a jet in a plasma sheet along with
  arbitrary angles between the magnetic field and velocity field In the
  force-free case the jet wake does not contain a neutral sheet but the
  field rotates through the flow to invert its polarity The presence
  of a magnetic field component aligned with the jet wake destroys the
  symmetric nature of the fastest growing modes leading to asymmetrical
  wake acceleration or equivalently jet deceleration In the case of a jet
  the instability properties depend both on the magnetic field and flow
  gradients as well as on the length of the jet We applied our results to
  the wake model of the solar wind on the solar equatorial plane above the
  helmet streamer cusp considering arbitrary angles between the magnetic
  field and the velocity field and to the post-termination shock jet
  recently found in 3D global heliospheric simulations where our analysis
  confirms and explains the stability properties found in such simulations

---------------------------------------------------------
Title: Modeling the Non-Relativistic Jets in R Aquarii
Authors: Korreck, K. E.; Sokoloski, J. L.; Opher, M.
2005AAS...207.1306K    Altcode: 2005BAAS...37.1173K
  R Aqr is a binary star system containing a Mira variable transferring
  material to a hot, compact object that is presumably a white dwarf. The
  accreting white dwarf produces non-relativistic jets, which have been
  observed at radio, optical, UV, and X-ray wavelengths. We are developing
  an MHD model to investigate the interaction of the jet with the ISM,
  and more broadly, the formation of the jet in this binary system. We
  are utilizing a block adaptive mesh refinement (AMR) MHD code that
  has been used to model various space physics plasmas to simulate the
  jets. We present X-ray spectral models based on our simulations and a
  comparison of these models with existing X-ray data for the northeast
  jet in the R Aqr binary system. We greatfully acknowledge funding from
  the National Science Foundation.

---------------------------------------------------------
Title: Kelvin-Helmholtz Instability and Turbulence Forming Behind
    a CME-driven Shock.
Authors: Manchester, W. B.; Opher, M.; Gombosi, T.; Dezeeuw, D.;
   Sokolov, I.; Toth, G.
2005AGUFMSH53A1245M    Altcode:
  We have found that a fast CME propagating through a bimodal solar wind
  produces variety of unexpected results. By means of a three-dimensional
  (3-D) numerical ideal magnetohydrodynamics (MHD) model we explore the
  interaction of a fast CME with a solar wind that possesses fast and
  slow speed solar wind at high and low latitude respectively. Within
  this model system, a CME erupts from the coronal streamer belt with
  an initial speed in excess of 1000 km/s which naturally drives a
  forward shock. An indentation in the shock forms at low latitude
  where it propagates through the slow solar wind. This indentation
  causes the fast-mode shock to deflect the flow toward the impinging
  flux rope. The plasma flow then must reverses direction to move around
  the rope, resulting in strong velocity shears. The shear flow is shown
  to be susceptible to the Kelvin-Helmholtz instability, which results
  in significant turbulence producing an environment very conducive to
  particle acceleration.

---------------------------------------------------------
Title: Effect of the Interstellar Magnetic Field on the Termination
Shock: Explaining the Voyager Results
Authors: Opher, M.; Stone, E. C.; Liewer, P. C.
2005AGUFMSH43B..02O    Altcode:
  After a twenty-seven year journey, Voyager 1 crossed the termination
  shock, the first boundary separating the solar system from the
  rest of the galaxy, and is now on the other side exploring the
  heliosheath. Since mid-2002 Voyager 1 has been observing strong beams
  of energetic particles coming outward along the spiral magnetic field,
  the opposite of the direction expected for particles accelerated
  at the shock. This can be explained if the shock is non-spherical
  so that the interplanetary magnetic field lines cross the shock and
  reenters the solar wind before reaching Voyager 1. This configuration
  has been invoked recently (Jokipii et al. 2004; Stone et al. 2005)
  to reconcile the data recently collected and explain how Voyager 1
  can detect energetic particles accelerated at the shock several years
  before crossing it. We show that the termination shock is, in fact,
  non-spherical due the distortion caused by an inclined interstellar
  magnetic field. We use the best values for the direction of the
  interstellar magnetic field (derived by Frisch 2003; and Lallement
  et al. 2005) showing that the shape of the termination shock depends
  strongly on the direction of the interstellar magnetic field. We also
  make predictions for Voyager 2 that will encounter the shock in the
  next couple of years.

---------------------------------------------------------
Title: Evolution of CME-driven Shocks in the Lower Corona for the
    October-November 2003 Events
Authors: Opher, M.; Manchester, W.; Gombosi, T.; Liewer, P.; Roussev,
   I.; Sokolov, I.; Dezeeuw, D.; Toth, G.
2005AGUSMSH13B..03O    Altcode:
  While it is generally accepted that the largest energetic particle
  events are created by CME-driven shocks in interplanetary space, the
  relative importance of CME-driven shocks versus flare-related processes
  in creating energetic particles low in the corona is not understood
  and is an area of active research. We analyzed the formation of CME
  driven shocks in the lower corona for the Halloween Space Storms
  that occurred in late October and early November 2003. We used the
  Space Weather Modeling Framework (SWMF) developed at the University
  of Michigan to create a realistic corona. The CME was modeled as an
  out of equilibrium flux rope lying under a closed field region in the
  AR 10486. The MHD code was first used to create realistic background
  corona using observed photospheric fields for boundary conditions for
  the Carrington rotation 2008. The background corona was validated by
  comparing results from the model with in situ solar wind observations
  from ACE/WIND. We discuss the magnetosonic speed profile in the lower
  corona and the consequences for the CME shock formation. Consequences
  for the acceleration of particles to GeV/nucleon are discussed. The
  computational runs were performed at the supercomputer Columbia at
  NASA/AMES.

---------------------------------------------------------
Title: Effects of a Tilted Heliospheric Current Sheet in the
    Heliosheath
Authors: Opher, M.; Liewer, P.; Velli, M.; Gombosi, T.; Manchester,
   W.; Dezeeuw, D.; Toth, G.
2005AGUSMSH23A..07O    Altcode:
  Effects of a Tilted Heliospheric Current Sheet in the Heliosheath
  Recent observations indicate that Voyager 1, now beyond 90 AU, is in a
  region unlike any encountered in it's 26 years of exploration. There
  is currently a controversy as to whether Voyager 1 has already
  crossed the Termination Shock, the first boundary of the Heliosphere
  (Krimigis et al. 2003; McDonald et al. 2003, Burlaga et al. 2003). An
  important aspect of this controversy is our poor understanding
  of this region. The region between the Termination Shock and the
  Heliopause, the Helisheath, is one of the most unknown regions
  theoretically. In the Heliosheath magnetic effects are crucial,
  as the solar magnetic field is compressed at the Termination Shock
  by the slowing flow. Therefore, to accurately model the heliosheath
  the inclusion of the solar magnetic field is crucial. Recently, our
  simulations showed that the Heliosheath presents remarkable dynamics,
  with turbulent flows and a presence of a jet flow at the current sheet
  that is unstable due to magnetohydrodynamic instabilities (Opher et
  al. 2003; 2004). We showed that to capture these phenomena, spatial
  numerical resolution is a crucial ingredient, therefore requiring the
  use of an adaptive mesh refinement (AMR). These previous works assumed
  that the solar rotation and the magnetic axis were aligned. Here we
  present including, for the first time, the tilt of the heliocurrent
  sheet using a 3D MHD AMR simulation with BATS-R-US code. We discuss
  the effects on the global structure of the Heliosheath, the flows,
  turbulence and magnetic field structure. We access the consequences for
  the observations measured by Voyager 1 since mid-2002. This intensive
  computational run was done at the supercomputer Columbia at NASA/AMES

---------------------------------------------------------
Title: Effects of a Tilted Heliospheric Current Sheet in the
Heliosheath: 3D MHD Modeling
Authors: Opher, M.; Liewer, P.; Velli, M.; Gombosi, T.; Manchester,
   W.; Dezeeuw, D.; Toth, G.
2004AGUFMSH42A..02O    Altcode:
  Recent observations indicate that Voyager 1, now beyond 90 AU, is in
  a region unlike any encountered in it's 26 years of exploration. There
  is currently a controversy as to whether Voyager 1 has already crossed
  the Termination Shock, the first boundary of the Heliosphere (Krimigis
  et al. 2003; McDonald et al. 2003, Burlaga et al. 2003). An important
  aspect of this controversy is our poor understanding of this region. The
  region between the Termination Shock and the Heliopause, the Helisheath,
  is one of the most unknown regions theoretically. In the Heliosheath
  magnetic effects are crucial, as the solar magnetic field is compressed
  at the Termination Shock by the slowing flow. Therefore, to accurately
  model the Heliosheath the inclusion of the solar magnetic field is
  crucial. Recently, our simulations showed that the Heliosheath presents
  remarkable dynamics, with turbulent flows and a presence of a jet
  flow at the current sheet that is unstable due to magnetohydrodynamic
  instabilities (Opher et al. 2003; 2004). We showed that to capture
  these phenomena, spatial numerical resolution is a crucial ingredient,
  therefore requiring the use of an adaptive mesh refinement (AMR). These
  previous works assumed that the solar rotation and the magnetic axis
  were aligned. Here we present for the first time results including
  the tilt of the heliocurrent sheet using a 3D MHD AMR simulation, with
  BATS-R-US code. We discuss the effects on the global structure of the
  Heliosheath, the flows, turbulence and magnetic field structure. We
  assess the consequences for the observations measured by Voyager 1
  since mid-2002.

---------------------------------------------------------
Title: Effects of a Tilted Heliospheric Current Sheet at the Edge
    of the Solar System
Authors: Opher, M.; Liewer, P.; Manchester, W.; Gombosi, T.; DeZeeuw,
   D.; Toth, G.
2004AAS...205.4306O    Altcode: 2004BAAS...36.1412O
  Recent observations indicate that Voyager 1, now beyond 90 AU, is in
  a region unlike any encountered in it's 26 years of exploration. There
  is currently a controversy as to whether Voyager 1 has already crossed
  the Termination Shock, the first boundary of the Heliosphere (Krimigis
  et al. 2003; McDonald et al. 2003, Burlaga et al. 2003). An important
  aspect of this controversy is our poor understanding of this region. The
  region between the Termination Shock and the Heliopause, the Helisheath,
  is one of the most unknown regions theoretically. In the Heliosheath
  magnetic effects are crucial, as the solar magnetic field is compressed
  at the Termination Shock by the slowing flow. Therefore, to accurately
  model the heliosheath the inclusion of the solar magnetic field is
  crucial.Recently, our simulations showed that the Heliosheath presents
  remarkable dynamics, with turbulent flows and a presence of a jet
  flow at the current sheet that is unstable due to magnetohydrodynamic
  instabilities (Opher et al. 2003; 2004). We showed that to capture
  these phenomena, spatial numerical resolution is a crucial ingredient,
  therefore requiring the use of an adaptive mesh refinement (AMR). These
  previous works assumed that the solar rotation and the magnetic axis
  were aligned. Here we present for the first time results including the
  tilt of the heliocurrent sheet using a 3D MHD AMR simulation , with
  BATS-R-US code. We discuss the effects on the global structure of the
  Heliosheath, the flows, turbulence and magnetic field structure. We
  access the consequences for the observations measured by Voyager 1
  since mid-2002.

---------------------------------------------------------
Title: Magnetic Effects Change Our View of the Heliosheath
Authors: Opher, M.; Liewer, P. C.; Velli, M.; Gombosi, T. I.;
   Manchester, W.; Dezeeuw, D. L.; Toth, G.; Sokolov, I.
2004AIPC..719..105O    Altcode: 2004astro.ph..6184O
  There is currently a controversy as to whether Voyager 1 has
  already crossed the termination Shock, the first boundary of the
  heliosphere. The region between the termination shock and the
  heliopause, the heliosheath, is one of the most unknown regions
  theoretically. In the heliosheath magnetic effects are crucial,
  as the solar magnetic field is compressed at the termination shock
  by the slowing flow. Recently, our simulations showed that the
  heliosheath presents remarkable dynamics, with turbulent flows and
  the presence of a jet flow at the current sheet that is unstable due
  to magnetohydrodynamic instabilities. In this paper we review these
  recent results, and present an additional simulation with constant
  neutral atom background. In this case the jet is still present but with
  reduced intensity. Further study, e.g., including neutrals and the tilt
  of the solar rotation from the magnetic axis, is required before we can
  definitively address how the heliosheath behaves. Already we can say
  that this region presents remarkable dynamics, with turbulent flows,
  indicating that the heliosheath might be very different from what we
  previously thought.

---------------------------------------------------------
Title: Magnetic Effects at the Edge of the Solar System: MHD
    Instabilities, the de Laval Nozzle Effect, and an Extended Jet
Authors: Opher, M.; Liewer, P. C.; Velli, M.; Bettarini, L.; Gombosi,
   T. I.; Manchester, W.; DeZeeuw, D. L.; Toth, G.; Sokolov, I.
2004ApJ...611..575O    Altcode: 2004astro.ph..6182O
  To model the interaction between the solar wind and the interstellar
  wind, magnetic fields must be included. Recently, Opher et al. found
  that by including the solar magnetic field in a three-dimensional
  high-resolution simulation using the University of Michigan BATS-R-US
  code, a jet-sheet structure forms beyond the solar wind termination
  shock. Here we present an even higher resolution three-dimensional case
  in which the jet extends for 150 AU beyond the termination shock. We
  discuss the formation of the jet due to a de Laval nozzle effect and
  its subsequent large-period oscillation due to magnetohydrodynamic
  (MHD) instabilities. To verify the source of the instability, we
  also perform a simplified two-dimensional geometry MHD calculation
  of a plane fluid jet embedded in a neutral sheet with the profiles
  taken from our three-dimensional simulation. We find remarkable
  agreement with the full three-dimensional evolution. We compare both
  simulations and the temporal evolution of the jet, showing that the
  sinuous mode is the dominant mode that develops into a velocity-shear
  instability with a growth rate of 5×10<SUP>-9</SUP>s<SUP>-1</SUP>=0.027
  yr<SUP>-1</SUP>. As a result, the outer edge of the heliosphere presents
  remarkable dynamics, such as turbulent flows caused by the motion of
  the jet. Further study, including neutrals and the tilt of the solar
  rotation from the magnetic axis, is required before we can definitively
  address how this outer boundary behaves. Already, however, we can say
  that the magnetic field effects are a major player in this region,
  changing our previous notion of how the solar system ends.

---------------------------------------------------------
Title: Magnetic Effects and our Changing View of the Heliosheath
Authors: Liewer, P. C.; Opher, M.; Velli, M.; Gombosi, T. I.;
   Manchester, W.; DeZeeuw, D. L.; Toth, G.; Sokolov, I.
2004AAS...204.7208L    Altcode: 2004BAAS...36R.799L
  The Sun traveling through the interstellar medium carves out a
  bubble of solar wind called the Heliosphere. Recent observations
  indicate that Voyager 1, now beyond 90 AU, is in a region unlike
  any encountered in it's 26 years of exploration. There is currently
  a controversy as to whether or not Voyager 1 has already crossed the
  Termination Shock, the first boundary of the Heliosphere (Krimigis et
  al. 2003; McDonald et al. 2003, Burlaga et al. 2003). The controversy
  stems from different interpretations of observations from several
  instruments. Contributing to this controversy is our poor understanding
  of the outer heliosphere. The region between the Termination Shock and
  the Heliopause, the Heliosheath, is one of the most unknown regions
  theoretically. In the Heliosheath magnetic effects are crucial, as
  the solar magnetic field is compressed at the Termination Shock by the
  slowing flow. Recently, our simulations showed that the Heliosheath is
  remarkably dynamic, with turbulent flows resulting from an unstable
  jet flow at the current sheet (Opher et al. 2003; 2004). In this
  talk we review these recent results, and present additional results
  from simulations of the unstable jet with a constant neutral atom
  background. Further studies which include additional effects such
  as the tilt between the solar rotation axis and the magnetic axis,
  are required before we can definitively address the structure and
  dynamics of the outer heliosphere. Already we can say that this region
  presents remarkable dynamics, with turbulent flows, indicating that
  the Heliosheath might be very different from what we previously thought.

---------------------------------------------------------
Title: Learning from our Sun: The Interaction of Stellar with
    Interstellar Winds
Authors: Opher, M.; Liewer, P. C.; Velli, M.; Gombosi, T. I.;
   Manchester, W.; DeZeeuw, D. L.; Toth, G.; Sokolov, I. V.
2004AAS...204.0303O    Altcode: 2004BAAS...36..671O
  Stars have winds which interact with the interstellar medium. The
  intensity of the winds can be 10 million times greater than that of
  the solar wind. The magnetic fields of these stars can be orders of
  magnitude greater than that of the Sun. The rotation periods can be
  appreciably different from that of the Sun. A detailed description of
  the interaction of stellar winds with the interstellar winds has never
  been made. The interaction between the Sun and Interstellar Medium
  creates three major structures: Termination Shock, Heliopause and
  Bow Shock. Recently, we found (Opher et al. 2003, 2004) that beyond
  the region where the solar wind become subsonic, the Termination
  Shock, a jet-sheet structure forms in the equatorial plane of the
  Sun rotation axis. This structure forms due to the compression of the
  solar magnetic field by the interstellar wind. The structure of the
  jet-sheet resembles a the "brim of a baseball cap"- it extends beyond
  the Termination Shock for 150 AU (almost touching the Bow Shock) and
  has a width of 10AU. This result is due to a novel application of a
  state-of-art 3D Magnetohydrodynamic (MHD) code with a highly refined
  grid (0.75 AU 4 orders of magnitude smaller than the physical dimensions
  of the system). The jet-sheet is unstable and oscillates up and down
  due to a velocity shear instability. We showed that the sinuous mode
  is the dominant mode that develops into a velocity-shear-instability
  with a growth rate of 0.027 years<SUP>-1</SUP>. We are the first to
  predict the formation of this structure at the equatorial region in
  the interaction of magnetized rotating star and an external wind (for
  a stellar rotation and magnetic field axis aligned). In this work,
  we extend our previous solar studies and investigate the effect in
  other solar-like stars. We present the dependence of the jet-sheet
  structure and the velocity-shear instability on the star mass-loss rate
  and magnetic field. We discuss further applications to other stellar
  wind interactions and the observational limits for the detection of
  this structure.

---------------------------------------------------------
Title: Three-dimensional MHD simulation of a flux rope driven CME
Authors: Manchester, Ward B.; Gombosi, Tamas I.; Roussev, Ilia; de
   Zeeuw, Darren L.; Sokolov, I. V.; Powell, Kenneth G.; Tóth, GáBor;
   Opher, Merav
2004JGRA..109.1102M    Altcode:
  We present a three-dimensional (3-D) numerical ideal
  magnetohydrodynamics (MHD) model, describing the time-dependent
  expulsion of plasma and magnetic flux from the solar corona that
  resembles a coronal mass ejection (CME). We begin by developing a
  global steady-state model of the corona and solar wind that gives
  a reasonable description of the solar wind conditions near solar
  minimum. The model magnetic field possesses high-latitude coronal
  holes and closed field lines at low latitudes in the form of a
  helmet streamer belt with a current sheet at the solar equator. We
  further reproduce the fast and slow speed solar wind at high and low
  latitudes, respectively. Within this steady-state heliospheric model,
  conditions for a CME are created by superimposing the magnetic field
  and plasma density of the 3-D Gibson-Low flux rope inside the coronal
  streamer belt. The CME is launched by initial force imbalance within
  the flux rope resulting in its rapid acceleration to a speed of over
  1000 km/s and then decelerates, asymptotically approaching a final
  speed near 600 km/s. The CME is characterized by the bulk expulsion of
  ∼10<SUP>16</SUP> g of plasma from the corona with a maximum of ∼5 ×
  10<SUP>31</SUP> ergs of kinetic energy. This energy is derived from the
  free magnetic energy associated with the cross-field currents, which is
  released as the flux rope expands. The dynamics of the CME are followed
  as it interacts with the bimodal solar wind. We also present synthetic
  white-light coronagraph images of the model CME, which show a two-part
  structure that can be compared with coronagraph observations of CMEs.

---------------------------------------------------------
Title: Magnetic Effects at the Edge of the Solar System: MHD
    Instabilities, the de Laval nozzle effect and an Extended Jet
Authors: Opher, M.; Liewer, P. C.; Velli, M.; Gombosi, T.; Manchester,
   W.; DeZeeuw, D.
2003AAS...20313403O    Altcode: 2003BAAS...35.1421O
  To model the interaction between the solar system and the interstellar
  wind magnetic fields, ionized and neutral components besides cosmic
  rays must be included. Recently (Opher et al. ApJL 2003) found, that
  by including the solar magnetic field in an high resolution run with
  the University of Michigan BATS-R-US code, a jet-sheet structure forms
  beyond the Termination Shock. Here we discuss the formation of the jet
  and its subsequent large period oscillation due to magnetohydrodynamic
  instabilities. We perform in a simplified two dimensional geometry
  resistive magnetohydrodynamic calculation of a plane fluid jet embedded
  in a neutral sheet with the profiles taken from our simulation. We
  find remarkable agreement with the full three dimensional evolution. We
  present an even higher resolution three dimensional case where the jet
  extends for 150AU beyond the Termination Shock. We compare the temporal
  evolution of the jet showing that the sinuous mode is the dominant mode
  that develops into a velocity-shear-instability with a growth rate of
  5 × 10<SUP>-9</SUP> sec<SUP>-1</SUP>=0.027 years<SUP>-1</SUP>. As a
  result the outer edge of the heliosphere presents remarkable dynamics,
  such as turbulence and flows caused by the motion of the jet. Further
  study, e.g., including neutrals and the tilt of the solar rotation
  from the magnetic axis, is required before we can definitively address
  how this outer boundary behaves. Already, however, we can say that the
  magnetic field effects are a major player in this region changing our
  previous notion of how the solar system ends.

---------------------------------------------------------
Title: Magnetic Effects at the Edge of the Solar System: MHD
    Instabilities, the de Laval nozzle effect and an Extended Jet
Authors: Opher, M.; Liewer, P.; Velli, M.; Bettarini, L.; Gombosi,
   T. I.; Manchester, W.; Dezeeuw, D. L.; Toth, G.; Sokolov, I.
2003AGUFMSH11C1114O    Altcode:
  To model the interaction between the solar system and the interstellar
  wind magnetic fields, ionized and neutral components besides cosmic
  rays must be included. Recently (Opher et al. ApJL 2003) found, that
  by including the solar magnetic field in an high resolution run with
  the University of Michigan BATS-R-US code, a jet-sheet structure forms
  beyond the Termination Shock. Here we discuss the formation of the jet
  and its subsequent large period oscillation due to magnetohydrodynamic
  instabilities. We perform in a simplified two dimensional geometry
  resistive magnetohydrodynamic calculation of a plane fluid jet embedded
  in a neutral sheet with the profiles taken from our simulation. We
  find remarkable agreement with the full three dimensional evolution. We
  present an even higher resolution three dimensional case where the jet
  extends for 150AU beyond the Termination Shock. We compare the temporal
  evolution of the jet showing that the sinuous mode is the dominant mode
  that develops into a velocity-shear-instability with a growth rate of
  5 x 10<SUP>-9</SUP> sec<SUP>-1</SUP>=0.027 years<SUP>-1</SUP>. As a
  result the outer edge of the heliosphere presents remarkable dynamics,
  such as turbulence and flows caused by the motion of the jet. Further
  study, e.g., including neutrals and the tilt of the solar rotation
  from the magnetic axis, is required before we can definitively address
  how this outer boundary behaves. Already, however, we can say that the
  magnetic field effects are a major player in this region changing our
  previous notion of how the solar system ends.

---------------------------------------------------------
Title: Probing the Edge of the Solar System: Formation of an Unstable
    Jet-Sheet
Authors: Opher, Merav; Liewer, Paulett C.; Gombosi, Tamas I.;
   Manchester, Ward; DeZeeuw, Darren L.; Sokolov, Igor; Toth, Gabor
2003ApJ...591L..61O    Altcode: 2003astro.ph..5420O
  The Voyager spacecraft is now approaching the edge of the solar
  system. Near the boundary between the solar system and the interstellar
  medium we find that an unstable “jet-sheet” forms. The jet-sheet
  oscillates up and down because of a velocity shear instability. This
  result is due to a novel application of a state-of-the-art
  three-dimensional MHD code with a highly refined grid. We assume
  as a first approximation that the solar magnetic and rotation axes
  are aligned. The effect of a tilt of the magnetic axis with respect
  to the rotation axis remains to be seen. We include in the model
  self-consistently magnetic field effects in the interaction between
  the solar and interstellar winds. Previous studies of this interaction
  had poorer spatial resolution and did not include the solar magnetic
  field. This instability can affect the entry of energetic particles
  into the solar system and the intermixing of solar and interstellar
  material. The same effect found here is predicted for the interaction
  of rotating magnetized stars possessing supersonic winds and moving
  with respect to the interstellar medium, such as O stars.

---------------------------------------------------------
Title: Probing the Edge of the Solar System: Formation of an Unstable
    Jet-Sheet
Authors: Opher, Merav
2003kas..confE..42O    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Interpreting Coronagraph Data used Simulated White Light
    Images and 3D MHD Models of CMEs
Authors: Liewer, P. C.; Opher, M.; Velli, M.; Manchester, W.; DeZeeuw,
   D.; Gombose, T.; Roussev, I.; Sokolov, I.; Toth, G.; Powell, K.
2003SPD....34.0511L    Altcode: 2003BAAS...35Q.816L
  We use a 3D time-dependent MHD model of a CME to try to understand the
  relationship between the CME structure and the bright features seen
  in coronagraph images. Questions addressed include whether the bright
  leading edge seen in LASCO coronagraph images of CMEs corresponds to
  compressed coronal material or shocked solar wind. We will analyze
  the evolution of the density and magnetic field as the CME propagates
  for CMEs of various field strengths and initial speeds. Coronagraph
  line-of-sight (LOS) images show 2D projections of the 3D density
  structure of the CME. Synthetic coronagraph images will be computed
  for the various CME cases to relate the structure to the LOS images. We
  use the University of Michigan BATS-R-US time-dependent adaptive grid
  MHD code to compute the CME evolution. The CME is created by inserting
  a flux-rope CME into a steady-state solution for the corona. The flux
  rope is anchored at both ends in the photosphere and embedded in a
  helmet streamer; it is not initially in equilibrium. The subsequent
  evolution of the flux rope - its expansion and propagation through the
  corona to 1 AU - is computed self-consistently with the evolution of
  the background corona and solar wind.

---------------------------------------------------------
Title: The Formation of an Unstable Jet-Sheet at the Edge of the
    Solar System
Authors: Opher, M.; Liewer, P.; Velli, M.; Gombosi, T.; Manchester,
   W.; DeZeeuw, D.; Sokolov, I.; Toth, G.
2003SPD....34.0604O    Altcode: 2003BAAS...35Q.818O
  We find that the boundary between the solar system and the interstellar
  medium an unstable jet-sheet forms. The jet is unstable and oscillates
  up and down due to Kelvin-Helmholtz type instability. We use a
  state-of-art 3D MHD code art with an adaptive grid mesh especially
  designed to refine the region at the current sheet and in the region
  between the termination shock and the heliopause. In the present study
  we assume as a first approximation that the solar magnetic field and
  rotation axis are aligned. We include in the model self-consistently
  magnetic field effects in the interaction between the solar and
  interstellar winds. Previous studies of this interaction had poorer
  spatial resolution and did not include the solar magnetic field. We
  present results from three different resolutions (ranging from 0.5AU to
  6AU at the current sheet) and discuss the effect of resolution on the
  characteristics of the jet such as strength and width. We show that in
  order to resolve the jet, there is a need of a resolution higher than
  3-4AU, the resolution used in previous studies. The neutrals interacting
  with the plasma component by charge-exchange interactions can affect
  the formation of the jet and we present results discussing their effect.

---------------------------------------------------------
Title: 3D MHD description of the region beyond the termination shock:
    The behaviour of the Current Sheet
Authors: Opher, M.; Liewer, P.; Gombosi, T.; Manchester, W.; Dezeeuw,
   D. L.; Powell, K.; Sokolov, I.; Toth, G.; Velli, M.
2002AGUFMSH21A0485O    Altcode:
  A fully self consistent MHD study of the heliosheath region is carried
  out, using BATSRUS, a three dimensional time dependent adaptive grid
  magnetohydrodynamic (MHD) model. The heliosheath, located between
  the termination shock and the heliopause, has not been studied in
  detail. At the termination shock the solar wind passes from a supersonic
  to a subsonic regime decelerating until it reaches the heliopause
  where it is diverted to the heliotail. This region is intersected
  in the equatorial plane (assuming a no-tilt for the dipole field)
  by a current sheet as the solar magnetic field changes polarity. One
  of the major questions is whether the current sheet remains at the
  equatorial plane. The magnetic field of the solar wind is included. In
  order to isolate the effects at this region we assumed no magnetic
  field in the interstellar medium. We observe a much faster flow of the
  current sheet, where the compressed azimuthal magnetic field is absent,
  leading to large velocity shear. With BATSRUS, we were able to obtain
  high resolution needed to analyze the behavior of this complicated
  regime, in particular the stability of the current sheet. We report
  the results and comment on the major processes responsible.

---------------------------------------------------------
Title: 3D MHD Simulation of CME Propagation from Solar Corona to 1 AU
Authors: Manchester, W. B.; Roussev, I.; Opher, M.; Gombosi, T.;
   Dezeeuw, D.; Toth, G.; Sokolov, I.; Powell, K.
2002AGUFMSH21A0501M    Altcode:
  We present a three-dimensional (3D) numerical ideal magnetohydrodynamics
  (MHD) model describing the time-dependent expulsion of a CME from
  the solar corona propagating all the way to 1 A.U.. The simulations
  are performed using the BATS-R-US (Block Adaptive Tree Solarwind Roe
  Upwind Scheme) code. We begin by developing a global steady-state
  model of the corona that possesses high-latitude coronal holes and
  a helmet streamer structure with a current sheet at the equator. The
  Archimedian spiral topology of the interplanetary magnetic field is
  reproduced along with fast and slow speed solar wind at high and
  low latitudes respectively. Within this model system, we drive a
  CME to erupt by the introduction of a Gibson-Low magnetic flux rope
  that is anchored at both ends in the photosphere and embedded in the
  helmet streamer in an initial state of force imbalance. The flux rope
  then rapidly accelerates to speeds in excess of 1500 km/sec driving
  a strong MHD shock as part of the CME. We find that both the shock
  front and the flux rope are strongly effected by bi-modal solar wind
  as the CME travels to 1 AU. Physics based AMR allows us to capture
  the complexity of the CME development and propagation focused on a
  particular Sun-Earth line. The applied numerical algorithm is designed
  to use optimal computational resources for the sake of tracing CMEs
  with very high spatial resolution all the way from Sun to Earth. We
  compare the model CME plasma parameters at 1 AU to observations and
  find the event to be geoeffective.

---------------------------------------------------------
Title: 3D MHD Simulations of Flux Rope Driven CMEs
Authors: Manchester, W. B.; Roussev, I.; Opher, M.; Gombosi, T.;
   DeZeeuw, D.; Toth, G.; Sokolov, I.; Powell, K.
2002AGUSMSH22D..03M    Altcode:
  We present a three-dimensional (3D) numerical ideal magnetohydrodynamics
  (MHD) model describing the time-dependent expulsion of a CME from
  the solar corona propagating all the way to 1 A.U.. The simulations
  are performed using the BATS-R-US (Block Adaptive Tree Solarwind Roe
  Upwind Scheme) code. We begin by developing a global steady-state
  model of the corona that possesses high-latitude coronal holes and
  a helmet streamer structure with a current sheet at the equator. The
  Archimedian spiral topology of the interplanetary magnetic field is
  reproduced along with fast and slow speed solar wind at high and low
  latitudes respectively. Within this model system,we drive a CME to erupt
  by the introduction of a twisted magnetic flux rope that is anchored at
  both ends in the photosphere and embedded in the helmet streamer. The
  flux rope configuration that we employ was first developed by Gibson
  and Low as part of a 3D self-similar model of a CME. In this case,
  the flux rope has the form of a spherical ball of twisted magnetic
  field distorted to a tear shape by a stretching transformation. The
  stretch transformation produces an outward radially directed Lorentz
  force within the flux rope that rapidly accelerates the leading edge of
  the rope to speeds of 1800 km/sec, driving a strong shock as part of
  the CME. We follow the evolution of the CME from the low corona as it
  makes its way through the heliosphere. We explore the dynamics of the
  expanding flux rope as it interacts with the rotating, bi-modal solar
  wind to determine significant MHD effects. Finally we present synthetic
  white-light coronagraph images of the model CME which show a three-part
  structure that can be compared with observations of CME structure.

---------------------------------------------------------
Title: 3D adaptive grid MHD simulations of the global heliosphere
    with self- consistent fluid neutral hydrogen
Authors: Opher, M.; Liewer, P.; Gombosi, T.; Manchester, W.; Dezeeuw,
   D.; Powell, K.; Sokolov, I.; Toth, G.
2002cosp...34E.835O    Altcode: 2002cosp.meetE.835O
  A three dimensional adaptive grid magnetohydrodynamic (MHD) model of
  the interaction of the solar wind with the local interstellar medium
  is presented. The code used is the BATS-R-US time-dependent adaptive
  grid three-dimensional magnetohydrodynamic, which is similar to the
  code used by Linde et al. JGR, 103, 1889 (1998). The magnetic field
  of both the solar wind and the interstellar medium are included. The
  latitute dependence of the solar wind is also taken into account. The
  neutral atoms are included self-consistently as a fluid, without
  assuming constant the density, velocity or temperature as previous
  3D MHD studies. The location of the termination shock and heliopause
  in the steady state solution for different values and directions of
  interstellar magnetic field are presented and compared with previous
  results. We also present results where we isolated the effects of
  neutrals and magnetic field showing their relative importance, in
  particular the heliopause.

---------------------------------------------------------
Title: Magnetic Field Generation in Galactic Plasmas
Authors: Opher, M.; Cowley, S.; Schekochihin, A.; Kinney, R. M.;
   Chandran, B.; Maron, J.; McWilliams, J. C.
2001AAS...198.5411O    Altcode: 2001BAAS...33..866O
  The origin of the magnetic field in the universe is one of the great
  problems in astrophysics. The observed magnetic fields in spiral
  galaxies, for example, are of the order of microgauss and are coherent
  over galactic scales. Its is usually assumed that turbulent fluid
  motions will enhance a seed field. In the present work we invetigate
  the growth of the magnetic field in plasmas with high magnetic Prandtl
  number (the ratio of viscosity to resistivity). This growth occur
  initially at scales below the viscous scale [1]. Kinney et al. [2]
  showed that in 2D the field saturates at an amplitude independent of
  the mean scale of the field. We discuss the initial growth in the three
  dimensional case where the dynamics of the field on scales less than
  the viscosity scale [3]. At low initial field, the field grows and
  the scale decreases until the resistive scale is reached. The field
  then grows at a reduced rate until it reaches an equilibrium with
  the mean scale at a resistive scale. At higher initial amplitude,
  the field saturates before the mean scale has decreased to the
  resistive scale. The subsequent evolution is a slow decrease of the
  scale to the resistive scale, at which point it reaches equilibrium
  and stops evolving. To explain the large scale coherence of galactic
  fields, an inverse cascade is necessary. There is no evidence of an
  inverse cascade. We will present results for extended physics models
  including tensor viscosity and ambipular diffusion. [1] R. Kulsrud, and
  S. Anderson, Astrophys. J., 396, 606 (1992); A. Gruzinov, S. Cowley,
  and R. Sudan, Phys.Rev.Lett., 77, 4342 (1996). [2] R. M. Kinney,
  B. Chandran, S. Cowley, J. C. McWilliams, Astrophys. J., accepted
  to publication (2000). [3] M. Opher, S. Cowley, A. Schekochihin,
  R. M. Kinney, B. Chandran, J. Maron and J.C. McWilliams, in preparation
  (2001).

---------------------------------------------------------
Title: Magnetic-Field Structure and Saturation in the Small-Scale
    Dynamo Theory
Authors: Schekochihin, A.; Maron, J.; Opher, M.; Cowley, S.
2001AAS...198.9001S    Altcode: 2001BAAS...33..918S
  A weak magnetic field passively advected by a turbulent velocity
  field grows exponentially while its characteristic scale decays. In
  the interstellar medium and protogalactic plasmas, the magnetic
  Prandtl number is very large. and the kinematic stage of magnetic
  dynamo therefore produces a broad spectrum of magnetic fluctuations
  on small (subviscous) scales. The distribution of the field stregth
  in the kinematic regime is lognormal (highly intermittent). A study
  of statistical correlations that are set up in the field pattern shows
  that the magnetic field lines possess a folding structure, where most
  of the characteristic-scale decrease is due to the field variation
  across itself (rapid transverse direction reversals), while the scale
  of the field variation along itself stays approximately constant. The
  field structure determines the conditions under which the nonlinear
  effects set in. We find that the advent of Lorentz back reaction leads
  to saturation of the magnetic energy and a substatial suppression of the
  intermittency of the field distribution. The folding pattern persists
  into the nonlinear stage, but the decrease of the magnetic-field scales
  is arrested. Our findings derive from the statistical theory of the
  small-scale magnetic fluctuations in the viscosity-dominated regime
  and are corroborated by an array of numerical simulations. This work
  was supported by the NSF Grant No. AST 97-13241 and the DOE Grant
  No. DE-FG03-93ER54 224.

---------------------------------------------------------
Title: Nuclear reaction rates and energy in stellar plasmas: The
    effect of highly damped modes
Authors: Opher, Merav; Silva, Luis O.; Dauger, Dean E.; Decyk, Viktor
   K.; Dawson, John M.
2001PhPl....8.2454O    Altcode: 2001astro.ph..5153O
  The effects of the highly damped modes in the energy and reaction rates
  in a plasma are discussed. These modes, with wave numbers k&gt;&gt;kD,
  even being only weakly excited, with less than kBT per mode, make a
  significant contribution to the energy and screening in a plasma. When
  the de Broglie wavelength is much less than the distance of closest
  approach of thermal electrons, a classical analysis of the plasma can
  be made. It is assumed, in the classical analysis, with ℏ--&gt;0,
  that the energy of the fluctuations ℏω&lt;&lt;kBT. Using the
  fluctuation-dissipation theorem, the spectra of fluctuations with
  ℏ≠0 is appreciably decreased. The decrease is mainly for the
  highly damped modes at high frequencies (~0.5-3kBT). Reaction rates are
  enhanced in a plasma due to the screening of the reacting ions. This
  is taken into account by the Salpeter factor, which assumes slow
  motion for the ions. The implication of including the highly damped
  modes (with ℏ≠0) in the nuclear reaction rates in a plasma is
  discussed. Finally, the investigations presently done on these effects
  in particle simulations with the sheet model and the multiparticle
  quantum simulation code are described.

---------------------------------------------------------
Title: Magnetic Field Generation in Galactic Plasmas
Authors: Opher, Merav; Cowley, Steve; Maron, Jason; McWilliams, James
2000APS..DPPBP1057O    Altcode:
  The origin of the magnetic field in the universe is one of the great
  problems in astrophysics. The observed magnetic fields in spiral
  galaxies, for example, are of the order of microgauss and are coherent
  over galactic scales. It is usually assumed that turbulent fluid motions
  will enhance a seed field. In the present work we investigate the growth
  of the magnetic field in plasmas with high magnetic Prandtl number
  (the ratio of viscosity to resistivity). This growth occurs initially
  at scales below the viscous scale [1]. Kinney et al. [2] showed that in
  2D the field saturates at an amplitude independent of the mean scale of
  the field. We discuss the initial growth in the three dimensional case
  where the dynamics of the field are on scales less than the viscosity
  scale [3]. At low initial field, the field grows and the scale decreases
  until the resistive scale is reached. The field then grows at a reduced
  rate until it reaches an equilibrium with the mean scale at a resistive
  scale. At higher initial amplitude, the field saturates before the mean
  scale has decreased to the resistive scale. The subsequent evolution
  is a slow decrease of the scale to the resistive scale, at which point
  it reaches equilibrium and stops evolving. To explain the large scale
  coherence of galactic fields, an inverse cascade is necessary. There
  is no evidence of an inverse cascade. We will present results for
  extended physics models including tensor viscosity and ambipular
  diffusion. [1] R. Kulsrud, and S. Anderson, Astrophys. J., 396, 606
  (1992); A. Gruzinov, S. Cowley, and R. Sudan, Phys.Rev.Lett., 77, 4342
  (1996). [2] R. M. Kinney, B. Chandran, S. Cowley, J. C. McWilliams,
  Astrophys. J., accepted to publication (2000). [3] M. Opher, S. Cowley,
  R. M. Kinney, B. Chandran, J. Maron and J.C. McWilliams, in preparation
  (2000).

---------------------------------------------------------
Title: Nuclear Reaction Rates in a Plasma: The Effect of Highly
    Damped Modes
Authors: Opher, Merav; Opher, Reuven
2000astro.ph..6326O    Altcode:
  The fluctuation-dissipation theorem is used to evaluate the screening
  factor of nuclear reactions due to the electromagnetic fluctuations in
  a plasma. We show that the commonly used Saltpeter factor is obtained
  if only fluctuations near the plasma eigenfrequency are assumed to be
  important (\omega \sim \omega_{pe}\ll T (\hbar=k_{B}=1)). By taking
  into account all the fluctuations, the highly damped ones, with \omega
  &gt;\omega_{pe}, as well as those with \omega\leq\omega_{pe}, we find
  that nuclear reaction rates are higher than those obtained using the
  Saltpeter factor, for many interesting plasmas.

---------------------------------------------------------
Title: Dynamic Screening in Thermonuclear Reactions
Authors: Opher, Merav; Opher, Reuven
2000ApJ...535..473O    Altcode: 1999astro.ph..8218O
  It has recently been argued that there are no dynamic screening
  corrections to Salpeter's enhancement factor in thermonuclear reactions,
  in the weak-screening limit. Two arguments were used: (1) the Gibbs
  probability distribution is factorable into two parts, one of which,
  exp(-βe<SUB>i</SUB>e<SUB>j</SUB>/r<SUB>ij</SUB>) (β=1/k<SUB>B</SUB>T),
  is independent of velocity space, and (2) the enhancement factor is
  w=1+β<SUP>2</SUP>e<SUP>2</SUP>Z<SUB>1</SUB>Z<SUB>2</SUB>&lt;φ<SUP>2</SUP>&gt;
  with
  &lt;φ<SUP>2</SUP>&gt;<SUB>k</SUB>=&lt;E<SUP>2</SUP>&gt;<SUB>k</SUB>/k<SUP>2</SUP>
  and &lt;E<SUP>2</SUP>&gt;<SUB>k</SUB>/(8π)=(T/2)[1-ɛ<SUP>-
  1</SUP>(0,k)]. We show that both of these arguments are incorrect.

---------------------------------------------------------
Title: Change in Primordial Abundances Due to a Change in the
    Primordial Plasma Energy Density
Authors: Opher, M.; Opher, R.
2000IAUS..198..116O    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The energy of the primordial plasma
Authors: Opher, M.; Opher, R.
2000NuPhS..80C0416O    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Energy of a Plasma in the Classical Limit
Authors: Opher, Merav; Opher, Reuven
1999PhRvL..82.4835O    Altcode: 1999astro.ph..6018O
  When λ<SUB>T</SUB>&lt;&lt;d<SUB>T</SUB>, where λ<SUB>T</SUB> is the
  de Broglie wavelength and d<SUB>T</SUB> is the distance of closest
  approach of thermal electrons, a classical analysis of the energy of
  a plasma can be made. In all the classical analysis made until now,
  it was assumed that the frequency of the fluctuations ω&lt;&lt;T,
  ( k<SUB>B</SUB> = ħ = 1). Using the fluctuation-dissipation theorem,
  we evaluate the energy of a plasma, allowing the frequency of the
  fluctuations to be arbitrary. We find that the energy density is
  appreciably larger than previously thought for many interesting plasmas,
  such as the plasma of the Universe before the recombination era.

---------------------------------------------------------
Title: Energy in the Primordial Plasma
Authors: Opher, Merav; Opher, Reuven
1999magr.meet.1339O    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Seed magnetic Fields Generated by Primordial Supernova
    Explosions
Authors: Miranda, Oswaldo D.; Opher, Merav; Opher, Reuven
1998MNRAS.301..547M    Altcode: 1998astro.ph..8161M
  The origin of the magnetic field in galaxies is an open question
  in astrophysics. Several mechanisms have been proposed related,
  in general, to the generation of small seed fields amplified by a
  dynamo mechanism. In general, these mechanisms have difficulty in
  satisfying both the requirements of a sufficiently high strength for
  the magnetic field and the necessary large coherent scales. We show
  that the formation of dense and turbulent shells of matter, in the
  multiple explosion scenario of Miranda &amp; Opher for the formation
  of the large-scale structures of the Universe, can naturally act as a
  seed for the generation of a magnetic field. During the collapse and
  explosion of Population III objects, a temperature gradient not parallel
  to a density gradient can naturally be established, producing a seed
  magnetic field through the Biermann battery mechanism. We show that
  seed magnetic fields ~10^-12-10^-14G can be produced in this multiple
  explosion scenario on scales of the order of clusters of galaxies
  (with coherence length L~1.8Mpc) and up to ~4.5x10^-10G on scales of
  galaxies (L~100kpc).

---------------------------------------------------------
Title: Less Energy in the Early Universe
Authors: Opher, M.; Opher, R.
1998tx19.confE.189O    Altcode:
  The standard energy calculation of the primordial plasma assumes ideal
  gas particles and that the electromagnetic spectrum is a blackbody
  spectrum in vacuum. Through the fluctuation-dissipation theorem (FDT),
  used in the studies of Opher and Opher (Phys.Rev.Lett. 79, 2628 (1997)
  and Phys.Rev.D 56, 3296 (1997)), we estimate the energy contained in
  the electromagnetic fluctuations. We show that the energy density of the
  plasma is appreciably less than the standard calculation, approximately
  -10% rho<SUB>gamma</SUB> for temperatures ~10<SUP>10</SUP> K, where
  rho<SUB>gamma</SUB> is the blackbody energy density in vacuum. This
  correction is appreciably different from the usual one using a finite
  temperature QED calculation. The reason is that FDT takes into account
  all the fluctuations in the plasma (not only the photon and plasmons),
  and includes dynamic screening, as well. We discuss the differences
  between the two approaches.

---------------------------------------------------------
Title: Additional Energy at the Epoch of Primordial Nucleosynthesis
Authors: Opher, M.
1998tsra.conf..248O    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Was The Electromagnetic Spectrum A Blackbody Spectrum In The
    Early Universe?
Authors: Opher, Merav; Opher, Reuven
1997PhRvL..79.2628O    Altcode: 1997astro.ph..8246O
  It is generally assumed that the electromagnetic spectrum in the
  primordial universe was a blackbody spectrum in vacuum. We derive the
  electromagnetic spectrum based on the fluctuation-dissipation theorem
  that describes the electromagnetic fluctuations in a plasma. Our
  description includes thermal and collisional effects in a plasma. The
  electromagnetic spectrum obtained differs from a blackbody spectrum
  in vacuum at low frequencies. In particular, concentrating on the
  primordial nucleosynthesis era, it has more energy than the blackbody
  spectrum for frequencies less than 3ω<SUB>pe</SUB> to 6ω<SUB>pe</SUB>,
  where ω<SUB>pe</SUB> is the electron plasma frequency.

---------------------------------------------------------
Title: Magnetic field spectrum in a plasma in thermal equilibrium
    in the epoch of primordial nucleosynthesis
Authors: Opher, Merav; Opher, Reuven
1997PhRvD..56.3296O    Altcode: 1997astro.ph..8251O
  The low-frequency magnetic field spectrum in the primordial plasma is
  of particular interest as a possible origin of magnetic fields in the
  universe (e.g., Tajima and co-workers and Cable and Tajima). We derive
  the magnetic field spectrum in the primordial plasma, in particular,
  at the epoch of primordial nucleosynthesis. The pioneering study of
  Cable and Tajima of the electromagnetic fluctuations, based on the
  fluctuation-dissipation theorem, is extended. Our model describes
  both the thermal and collisional effects in a plasma. It is based
  on a kinetic description with the Bhatnagar, Gross, and Krook (BGK)
  collision term. It is shown that the zero-frequency peak found by Cable
  and Tajima decreases. At high frequencies, the blackbody spectrum is
  obtained naturally without the necessity of the link procedure used by
  them. At low frequencies (ω&lt;=4ω<SUB>pe</SUB>, where ω<SUB>pe</SUB>
  is the electron plasma frequency), it is shown that the magnetic field
  spectrum has more energy than the blackbody spectrum in vacuum.

---------------------------------------------------------
Title: Origin of the Magnetic Field in Young Galaxies
Authors: Opher, M.; Opher, R.; Miranda, O. D.
1997ASPC..114..129O    Altcode: 1997ygqa.conf..129O
  No abstract at ADS

---------------------------------------------------------
Title: Primordial Magnetic Fields and the Formation of the First
    Objects in the Universe
Authors: Opher, Reuven; Miranda, Oswaldo D.; Oliveira, Sandra R.;
   Pires, Nilza; Opher, Merav
1996plas.work..162O    Altcode:
  We evaluate the effects of the various physical mechanisms that were
  present during and after the recombination era (photon drag, photon
  cooling, recombination, photoionization, collisional ionization,
  and hydrogen molecule production, destruction and cooling - see de
  Araujo &amp; Opher 1988, 1989, 1994) and a cosmological constant upon
  perturbation evolution for different initial perturbations. We rewrote
  the equations of de Araujo &amp; Opher in the Lagrangian formulation
  and calculate the internal structure of the primordial clouds. We
  show that the collapse and explosion of these objects can create a
  primordial magnetic field by the Biermann mechanism in the shocks
  created by the explosion of these objects.

---------------------------------------------------------
Title: Plasma effects on primordial nucleosynthesis
Authors: Opher, M.; Opher, R.
1994STIN...9622817O    Altcode:
  We modify the standard code of primordial nucleosynthesis to include
  plasma effects: (1) Plasmons (oscillations near the Langmuir frequency);
  and (2) The zero frequency fluctuations predicted by the Fluctuation
  Dissipation Theorem (FDT). We found a change in the He-4 yield,
  delta Y/Y approximately 10<SUP>-3</SUP> for the plasmons and delta
  Y/Y approximately 10<SUP>-4</SUP> for FDT. The result for the case of
  plasmons, for example, is an order of magnitude higher than the most
  recent correction to the He-4 abundance.

---------------------------------------------------------
Title: The formation of the large-scale structures of the universe
    and primordial magnetic field by supernovae explosions
Authors: Miranda, O. D.; Opher, M.; Opher, R.
1994spub.reptS....M    Altcode:
  The theory of galactic formation and of large-scale structure generally
  assumes that all existing structures of the universe were formed
  from perturbations present initially in a homogeneous and isotropic
  universe. We study here the formation of the large-scale structures
  beginning from the collapse of a Population III object which created a
  shock wave at high redshift. The influence of various physical processes
  in the evolution of the shock wave such as Compton cooling by the
  radiation background, is analyzed in detail. Our results demonstrate
  that it is possible to obtain large voids of matter of dimensions
  approximately 55-69 Mpc, and masses of the shells on the order of
  superclusters of galaxies. We suggest the creation of a primordial
  magnetic field by a Biermann type mechanism in the shocks of primordial
  supernovae. We estimate the magnetic field created in the shock as B
  approximately 10<SUP>-9</SUP>G. This field is subsequently amplified
  by an alpha<SUP>2</SUP> - dynamo mechanism in the turbulent region
  behind the shock.