lagg

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Author name code: lagg
ADS astronomy entries on 2022-09-14
author:"Lagg, Andreas"

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Title: Polarimetric calibration of the Sunrise UV Spectropolarimeter
and Imager
Authors: Iglesias, F. A.; Feller, A.; Gandorfer, A.; Lagg, A.;
Riethmüller, T. L.; Solanki, S. K.; Katsukawa, Y.; Kubo, M.;
Zucarelli, G.; Sanchez, M.; Sunrise Team
2022BAAA...63..305I Altcode:
Sunrise is an optical observatory mounted in a stratospheric balloon,
developed to study magnetic fields in the solar atmosphere with very
high resolution. In its third flight, Sunrise carry the Sunrise UV
Spectropolarimeter and Imager (SUSI), that operates in the 313-430 nm
range, covering thousands of spectral lines not accessible from the
ground and thus largely unexplored. SUSI does not include a polarimetric
calibration unit on board. We report about the development status of
SUSI and the preliminary results of its calibration.

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Title: Magnetized supersonic downflows in the chromosphere. A
statistical study using the He I 10 830 Å lines
Authors: Sowmya, K.; Lagg, A.; Solanki, S. K.; Castellanos Durán,
J. S.
2022A&A...661A.122S Altcode: 2022arXiv220211679S
The chromosphere above active regions (ARs) on the Sun hosts
magnetized supersonic downflows. Studies of these supersonic downflows
help to decipher the magnetic fine structure and dynamics of the
chromosphere. We perform a statistical analysis of the magnetized
supersonic downflows in a number of ARs at different evolutionary stages
and survey their characteristics. We analyze spectro-polarimetric scans
of parts of 13 ARs obtained in the infrared He I 10 830 Å triplet
formed in the upper chromosphere recorded with the GREGOR Infrared
Spectrograph mounted at the GREGOR solar telescope. We retrieve
the line-of-sight velocities and the magnetic field vector using
the HELIX+ inversion code that assumes Milne-Eddington
atmospheres. We find magnetized supersonic downflows in all the ARs,
with larger area coverage by such flows in ARs observed during their
emerging phase. The fact that supersonic downflows were detected
in all scans, albeit only covering a small fraction, 0.2-6.4%, of
the observed field-of-view, suggests that they are a comparatively
common phenomenon in the upper chromospheres of ARs. The supersonic
downflows are found to be associated with many AR features, such as
pores, sunspot umbrae, sunspot penumbrae, light bridges, plages, He
I loops as part of arch filament systems characteristic of emerging
fields, and filaments. Although several mechanisms are identified to be
causing the supersonic downflows, by far the most common one appears to
be the draining of plasma along the legs of rising magnetic loops. The
loops mainly drain into forming pores. The line-of-sight velocities of
the supersonic downflows reach values of up to 49 km s−1,
and the velocity distribution shows multiple populations. Almost 92% of
these supersonic downflows coexist with a subsonic flow component. The
weaker, more horizontal fields associated with the supersonic component
suggests that it is formed above the subsonic component.

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Title: The magnetic drivers of campfires seen by the Polarimetric
and Helioseismic Imager (PHI) on Solar Orbiter
Authors: Kahil, F.; Hirzberger, J.; Solanki, S. K.; Chitta, L. P.;
Peter, H.; Auchère, F.; Sinjan, J.; Orozco Suárez, D.; Albert,
K.; Albelo Jorge, N.; Appourchaux, T.; Alvarez-Herrero, A.; Blanco
Rodríguez, J.; Gandorfer, A.; Germerott, D.; Guerrero, L.; Gutiérrez
Márquez, P.; Kolleck, M.; del Toro Iniesta, J. C.; Volkmer, R.;
Woch, J.; Fiethe, B.; Gómez Cama, J. M.; Pérez-Grande, I.; Sanchis
Kilders, E.; Balaguer Jiménez, M.; Bellot Rubio, L. R.; Calchetti,
D.; Carmona, M.; Deutsch, W.; Fernández-Rico, G.; Fernández-Medina,
A.; García Parejo, P.; Gasent-Blesa, J. L.; Gizon, L.; Grauf, B.;
Heerlein, K.; Lagg, A.; Lange, T.; López Jiménez, A.; Maue, T.;
Meller, R.; Michalik, H.; Moreno Vacas, A.; Müller, R.; Nakai,
E.; Schmidt, W.; Schou, J.; Schühle, U.; Staub, J.; Strecker, H.;
Torralbo, I.; Valori, G.; Aznar Cuadrado, R.; Teriaca, L.; Berghmans,
D.; Verbeeck, C.; Kraaikamp, E.; Gissot, S.
2022A&A...660A.143K Altcode: 2022arXiv220213859K
Context. The Extreme Ultraviolet Imager (EUI) on board the Solar Orbiter
(SO) spacecraft observed small extreme ultraviolet (EUV) bursts,
termed campfires, that have been proposed to be brightenings near the
apexes of low-lying loops in the quiet-Sun atmosphere. The underlying
magnetic processes driving these campfires are not understood. Aims: During the cruise phase of SO and at a distance of 0.523
AU from the Sun, the Polarimetric and Helioseismic Imager on Solar
Orbiter (SO/PHI) observed a quiet-Sun region jointly with SO/EUI,
offering the possibility to investigate the surface magnetic field
dynamics underlying campfires at a spatial resolution of about 380
km. Methods: We used co-spatial and co-temporal data of the
quiet-Sun network at disc centre acquired with the High Resolution
Imager of SO/EUI at 17.4 nm (HRIEUV, cadence 2 s) and the
High Resolution Telescope of SO/PHI at 617.3 nm (HRT, cadence 2.5
min). Campfires that are within the SO/PHI−SO/EUI common field
of view were isolated and categorised according to the underlying
magnetic activity. Results: In 71% of the 38 isolated events,
campfires are confined between bipolar magnetic features, which seem to
exhibit signatures of magnetic flux cancellation. The flux cancellation
occurs either between the two main footpoints, or between one of the
footpoints of the loop housing the campfire and a nearby opposite
polarity patch. In one particularly clear-cut case, we detected the
emergence of a small-scale magnetic loop in the internetwork followed
soon afterwards by a campfire brightening adjacent to the location
of the linear polarisation signal in the photosphere, that is to
say near where the apex of the emerging loop lays. The rest of the
events were observed over small scattered magnetic features, which
could not be identified as magnetic footpoints of the campfire hosting
loops. Conclusions: The majority of campfires could be driven
by magnetic reconnection triggered at the footpoints, similar to the
physical processes occurring in the burst-like EUV events discussed
in the literature. About a quarter of all analysed campfires, however,
are not associated to such magnetic activity in the photosphere, which
implies that other heating mechanisms are energising these small-scale
EUV brightenings.

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Title: Similarities of magnetoconvection in the umbra and in the
penumbra of sunspots
Authors: Löptien, B.; Lagg, A.; van Noort, M.; Solanki, S. K.
2021A&A...655A..61L Altcode: 2021arXiv211001352L
Context. It is unclear why there is a rather sharp boundary in
sunspots between the umbra and the penumbra. Both regions exhibit
magnetoconvection, which manifests in penumbral filaments in the
penumbra and in umbral dots in the umbra. Aims: Here we compare
the physical properties of umbral dots and penumbral filaments. Our
goal is to understand how the properties of these convective features
change across the boundary between the umbra and the penumbra
and how this is related to the rapid increase in brightness at the
umbra-penumbra boundary. Methods: We derived ensemble averages
of the physical properties of different types of convective features
based on observations of two sunspots with Hinode. Results:
There are strong similarities between the convective features in the
outer parts of the umbra and the ones in the penumbra, with most
physical parameters being smooth and continuous functions of the
length of the features. Conclusions: Our results indicate
that the transition in brightness from the umbra to the penumbra
is solely caused by an increased effectiveness of magnetoconvection
within individual convective cells. There is no significant difference
in the number density of convective elements between the outer umbra
and the inner penumbra. Penumbral filaments exhibit a larger area and
a higher brightness compared to umbral dots. It is still unclear how
exactly the underlying magnetic field causes the increase in the size
and brightness of convective features in the penumbra.

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Title: Inferring magnetic helicity spectrum in spherical domains:
Method and example applications
Authors: Prabhu, A. P.; Singh, N. K.; Käpylä, M. J.; Lagg, A.
2021A&A...654A...3P Altcode: 2021arXiv210407588P
Context. Obtaining observational constraints on the role of turbulent
effects for the solar dynamo is a difficult, yet crucial, task. Without
such knowledge, the full picture of the operation mechanism of the
solar dynamo cannot be formed. Aims: The magnetic helicity
spectrum provides important information about the α effect. Here
we demonstrate a formalism in spherical geometry to infer magnetic
helicity spectra directly from observations of the magnetic field,
taking into account the sign change of magnetic helicity across the
Sun's equator. Methods: Using an angular correlation function of
the magnetic field, we develop a method to infer spectra for magnetic
energy and helicity. The retrieval of the latter relies on a fundamental
definition of helicity in terms of linkage of magnetic flux. We apply
the two-scale approach, previously used in Cartesian geometry, to
spherical geometry for systems where a sign reversal of helicity is
expected across the equator on both small and large scales. 
Results: We test the method by applying it to an analytical model
of a fully helical field, and to magneto-hydrodynamic simulations
of a turbulent dynamo. The helicity spectra computed from the vector
potential available in the models are in excellent agreement with the
spectra computed solely from the magnetic field using our method. In
a next test, we use our method to obtain the helicity spectrum from a
synoptic magnetic field map corresponding to a Carrington rotation. We
observe clear signs of a bihelical spectrum of magnetic helicity,
which is in complete accordance to the previously reported spectra
in literature from the same map. Conclusions: Our formalism
makes it possible to infer magnetic helicity in spherical geometry,
without the necessity of computing the magnetic vector potential. It
has many applications in solar and stellar observations, but can also
be used to analyse global magnetoconvection models of stars and to
compare them with observations.

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Title: How rare are counter Evershed flows?
Authors: Castellanos Durán, J. S.; Lagg, A.; Solanki, S. K.
2021A&A...651L...1C Altcode: 2021arXiv210605592S
One of the main characteristics of sunspot penumbrae is the radially
outward-directed Evershed flow. Only recently have penumbral regions
been reported with similar characteristics to normal penumbral
filaments but with an opposite direction of the flow. Such flows
directed toward the umbra are known as counter Evershed flows
(CEFs). We aim to determine the occurrence frequency of CEFs in
active regions (ARs) and to characterize their lifetime and the
prevailing conditions in the ARs. We analyzed the continuum images,
Dopplergrams, and magnetograms recorded by SDO/HMI of 97 ARs that
appeared from 2011 to 2017. We followed the ARs for 9.6 ± 1.4 days
on average. We found 384 CEFs in total, with a median value of six
CEFs per AR. Counter Evershed flows are a rather common feature,
occurring in 83.5% of all ARs regardless of the magnetic complexity
of the AR. However, CEFs were only observed, on average, during 5.9%
of the mean total duration of all the observations analyzed here. The
lifetime of CEFs follows a log-normal distribution with a median value
of 10.6−6.0+12.4 h. In addition, we report two
populations of CEFs, those that are associated with light bridges and
those that are not. We explain that the rarity of reports of CEFs in
the literature is a result of highly incomplete coverage of ARs with
spectropolarimetric data. By using the continuous observations now
routinely available from space, we are able to overcome this limitation.

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Title: The magnetic fine structure of the Sun's polar region as
revealed by Sunrise
Authors: Prabhu, A.; Lagg, A.; Hirzberger, J.; Solanki, S. K.
2020A&A...644A..86P Altcode:
Context. Polar magnetic fields play a key role in the solar magnetic
cycle and they are the source of a significant portion of the
interplanetary magnetic field. However, observations of the poles
are challenging and hence our understanding of the polar magnetic
environment is incomplete. Aims: We deduce properties of
small-scale magnetic features in the polar region using high-resolution
data and specifically aim to determine the flux per patch above which
one magnetic polarity starts to dominate over the other. Methods:
We study the high spatial resolution, seeing-free observations of the
north solar polar region, obtained with the IMaX instrument on-board
the balloon-borne SUNRISE observatory during June 2009, at the solar
activity minimum. We performed inversions of the full Stokes vector
recorded by IMaX to retrieve atmospheric parameters of the Sun's
polar region, mainly the temperature stratification and the magnetic
field vector. Results: We infer kilo-Gauss (kG) magnetic fields
in patches harbouring polar faculae, without resorting to a magnetic
filling factor. Within these patches we find the maxima of the magnetic
field to be near the dark narrow lanes, which are shifted towards the
disc centre side in comparison to the maxima in continuum intensity. In
contrast, we did not find any fields parallel to the solar surface
with kG strengths. In addition to the kG patches, we found the polar
region to be covered in patches of both polarities, which have a range
of sizes. We find the field strength of these patches to increase with
increasing size and flux, with the smaller patches showing a significant
dispersion in field strength. The dominating polarity of the north
pole during this phase of the solar cycle is found to be maintained
by the larger patches with fluxes above 2.3 × 1017 Mx.

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Title: The SUNRISE UV Spectropolarimeter and imager for SUNRISE III
Authors: Feller, Alex; Gandorfer, Achim; Iglesias, Francisco A.;
Lagg, Andreas; Riethmüller, Tino L.; Solanki, Sami K.; Katsukawa,
Yukio; Kubo, Masahito
2020SPIE11447E..AKF Altcode:
Sunrise is a balloon-borne solar observatory dedicated to the
investigation of key processes of the magnetic field and the plasma
flows in the lower solar atmosphere. The observatory operates in
the stratosphere at an altitude of around 37 km in order to avoid
image degradation due to turbulence in the Earth's atmosphere and to
access the UV range. The third science flight of Sunrise will carry new
instrumentation which samples the solar spectrum over a broad wavelength
domain from the UV to the near IR and covers an extended height range in
the solar atmosphere. A key feature of the Sunrise UV Spectropolarimeter
and Imager (SUSI) operating between 309 nm and 417 nm, is its capability
to simultaneously record a large number of spectral lines. By combining
the spectral and polarization information of many individual lines
with different formation heights and sensitivities, the accuracy and
the height resolution of the inferred atmospheric parameters can be
significantly increased. The spectral bands of SUSI are selected one
at a time by rotating a diffraction grating with respect to a fixed
polarimetry unit. The spatial and spectral field of view on the 2k x
2k cameras is 59" and 2.0 - 2.3 nm, respectively. A further innovation
is the numerical restoration of the spectrograph scans by means of
synchronized 2D context imaging, a technique that has recently produced
impressive results at ground-based solar observatories.

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Title: Sunrise Chromospheric Infrared SpectroPolarimeter (SCIP)
for sunrise III: system design and capability
Authors: Katsukawa, Y.; del Toro Iniesta, J. C.; Solanki, S. K.;
Kubo, M.; Hara, H.; Shimizu, T.; Oba, T.; Kawabata, Y.; Tsuzuki,
T.; Uraguchi, F.; Nodomi, Y.; Shinoda, K.; Tamura, T.; Suematsu,
Y.; Ishikawa, R.; Kano, R.; Matsumoto, T.; Ichimoto, K.; Nagata, S.;
Quintero Noda, C.; Anan, T.; Orozco Suárez, D.; Balaguer Jiménez,
M.; López Jiménez, A. C.; Cobos Carrascosa, J. P.; Feller, A.;
Riethmueller, T.; Gandorfer, A.; Lagg, A.
2020SPIE11447E..0YK Altcode:
The Sunrise balloon-borne solar observatory carries a 1 m aperture
optical telescope and provides us a unique platform to conduct
continuous seeing-free observations at UV-visible-IR wavelengths from
an altitude of higher than 35 km. For the next flight planned for
2022, the post-focus instrumentation is upgraded with new spectro-
polarimeters for the near UV (SUSI) and the near-IR (SCIP), whereas
the imaging spectro-polarimeter Tunable Magnetograph (TuMag) is capable
of observing multiple spectral lines within the visible wavelength. A
new spectro-polarimeter called the Sunrise Chromospheric Infrared
spectroPolarimeter (SCIP) is under development for observing near-IR
wavelength ranges of around 770 nm and 850 nm. These wavelength ranges
contain many spectral lines sensitive to solar magnetic fields and
SCIP will be able to obtain magnetic and velocity structures in the
solar atmosphere with a sufficient height resolution by combining
spectro-polarimetric data of these lines. Polarimetric measurements are
conducted using a rotating waveplate as a modulator and polarizing beam
splitters in front of the cameras. The spatial and spectral resolutions
are 0.2" and 2 105, respectively, and a polarimetric sensitivity of
0.03 % (1σ) is achieved within a 10 s integration time. To detect
minute polarization signals with good precision, we carefully designed
the opto-mechanical system, polarization optics and modulation, and
onboard data processing.

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Title: Coordination within the remote sensing payload on the Solar
Orbiter mission
Authors: Auchère, F.; Andretta, V.; Antonucci, E.; Bach, N.;
Battaglia, M.; Bemporad, A.; Berghmans, D.; Buchlin, E.; Caminade,
S.; Carlsson, M.; Carlyle, J.; Cerullo, J. J.; Chamberlin, P. C.;
Colaninno, R. C.; Davila, J. M.; De Groof, A.; Etesi, L.; Fahmy,
S.; Fineschi, S.; Fludra, A.; Gilbert, H. R.; Giunta, A.; Grundy,
T.; Haberreiter, M.; Harra, L. K.; Hassler, D. M.; Hirzberger, J.;
Howard, R. A.; Hurford, G.; Kleint, L.; Kolleck, M.; Krucker, S.;
Lagg, A.; Landini, F.; Long, D. M.; Lefort, J.; Lodiot, S.; Mampaey,
B.; Maloney, S.; Marliani, F.; Martinez-Pillet, V.; McMullin, D. R.;
Müller, D.; Nicolini, G.; Orozco Suarez, D.; Pacros, A.; Pancrazzi,
M.; Parenti, S.; Peter, H.; Philippon, A.; Plunkett, S.; Rich, N.;
Rochus, P.; Rouillard, A.; Romoli, M.; Sanchez, L.; Schühle, U.;
Sidher, S.; Solanki, S. K.; Spadaro, D.; St Cyr, O. C.; Straus, T.;
Tanco, I.; Teriaca, L.; Thompson, W. T.; del Toro Iniesta, J. C.;
Verbeeck, C.; Vourlidas, A.; Watson, C.; Wiegelmann, T.; Williams,
D.; Woch, J.; Zhukov, A. N.; Zouganelis, I.
2020A&A...642A...6A Altcode:
Context. To meet the scientific objectives of the mission, the Solar
Orbiter spacecraft carries a suite of in-situ (IS) and remote sensing
(RS) instruments designed for joint operations with inter-instrument
communication capabilities. Indeed, previous missions have shown that
the Sun (imaged by the RS instruments) and the heliosphere (mainly
sampled by the IS instruments) should be considered as an integrated
system rather than separate entities. Many of the advances expected
from Solar Orbiter rely on this synergistic approach between IS and
RS measurements. Aims: Many aspects of hardware development,
integration, testing, and operations are common to two or more
RS instruments. In this paper, we describe the coordination effort
initiated from the early mission phases by the Remote Sensing Working
Group. We review the scientific goals and challenges, and give an
overview of the technical solutions devised to successfully operate
these instruments together. Methods: A major constraint for the
RS instruments is the limited telemetry (TM) bandwidth of the Solar
Orbiter deep-space mission compared to missions in Earth orbit. Hence,
many of the strategies developed to maximise the scientific return from
these instruments revolve around the optimisation of TM usage, relying
for example on onboard autonomy for data processing, compression,
and selection for downlink. The planning process itself has been
optimised to alleviate the dynamic nature of the targets, and an
inter-instrument communication scheme has been implemented which can
be used to autonomously alter the observing modes. We also outline the
plans for in-flight cross-calibration, which will be essential to the
joint data reduction and analysis. Results: The RS instrument
package on Solar Orbiter will carry out comprehensive measurements
from the solar interior to the inner heliosphere. Thanks to the close
coordination between the instrument teams and the European Space
Agency, several challenges specific to the RS suite were identified
and addressed in a timely manner.

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Title: Models and data analysis tools for the Solar Orbiter mission
Authors: Rouillard, A. P.; Pinto, R. F.; Vourlidas, A.; De Groof, A.;
Thompson, W. T.; Bemporad, A.; Dolei, S.; Indurain, M.; Buchlin, E.;
Sasso, C.; Spadaro, D.; Dalmasse, K.; Hirzberger, J.; Zouganelis, I.;
Strugarek, A.; Brun, A. S.; Alexandre, M.; Berghmans, D.; Raouafi,
N. E.; Wiegelmann, T.; Pagano, P.; Arge, C. N.; Nieves-Chinchilla,
T.; Lavarra, M.; Poirier, N.; Amari, T.; Aran, A.; Andretta, V.;
Antonucci, E.; Anastasiadis, A.; Auchère, F.; Bellot Rubio, L.;
Nicula, B.; Bonnin, X.; Bouchemit, M.; Budnik, E.; Caminade, S.;
Cecconi, B.; Carlyle, J.; Cernuda, I.; Davila, J. M.; Etesi, L.;
Espinosa Lara, F.; Fedorov, A.; Fineschi, S.; Fludra, A.; Génot,
V.; Georgoulis, M. K.; Gilbert, H. R.; Giunta, A.; Gomez-Herrero, R.;
Guest, S.; Haberreiter, M.; Hassler, D.; Henney, C. J.; Howard, R. A.;
Horbury, T. S.; Janvier, M.; Jones, S. I.; Kozarev, K.; Kraaikamp,
E.; Kouloumvakos, A.; Krucker, S.; Lagg, A.; Linker, J.; Lavraud,
B.; Louarn, P.; Maksimovic, M.; Maloney, S.; Mann, G.; Masson, A.;
Müller, D.; Önel, H.; Osuna, P.; Orozco Suarez, D.; Owen, C. J.;
Papaioannou, A.; Pérez-Suárez, D.; Rodriguez-Pacheco, J.; Parenti,
S.; Pariat, E.; Peter, H.; Plunkett, S.; Pomoell, J.; Raines, J. M.;
Riethmüller, T. L.; Rich, N.; Rodriguez, L.; Romoli, M.; Sanchez,
L.; Solanki, S. K.; St Cyr, O. C.; Straus, T.; Susino, R.; Teriaca,
L.; del Toro Iniesta, J. C.; Ventura, R.; Verbeeck, C.; Vilmer, N.;
Warmuth, A.; Walsh, A. P.; Watson, C.; Williams, D.; Wu, Y.; Zhukov,
A. N.
2020A&A...642A...2R Altcode:
Context. The Solar Orbiter spacecraft will be equipped with a wide
range of remote-sensing (RS) and in situ (IS) instruments to record
novel and unprecedented measurements of the solar atmosphere and
the inner heliosphere. To take full advantage of these new datasets,
tools and techniques must be developed to ease multi-instrument and
multi-spacecraft studies. In particular the currently inaccessible
low solar corona below two solar radii can only be observed
remotely. Furthermore techniques must be used to retrieve coronal
plasma properties in time and in three dimensional (3D) space. Solar
Orbiter will run complex observation campaigns that provide interesting
opportunities to maximise the likelihood of linking IS data to their
source region near the Sun. Several RS instruments can be directed
to specific targets situated on the solar disk just days before
data acquisition. To compare IS and RS, data we must improve our
understanding of how heliospheric probes magnetically connect to the
solar disk. Aims: The aim of the present paper is to briefly
review how the current modelling of the Sun and its atmosphere
can support Solar Orbiter science. We describe the results of a
community-led effort by European Space Agency's Modelling and Data
Analysis Working Group (MADAWG) to develop different models, tools,
and techniques deemed necessary to test different theories for the
physical processes that may occur in the solar plasma. The focus here
is on the large scales and little is described with regards to kinetic
processes. To exploit future IS and RS data fully, many techniques have
been adapted to model the evolving 3D solar magneto-plasma from the
solar interior to the solar wind. A particular focus in the paper is
placed on techniques that can estimate how Solar Orbiter will connect
magnetically through the complex coronal magnetic fields to various
photospheric and coronal features in support of spacecraft operations
and future scientific studies. Methods: Recent missions such as
STEREO, provided great opportunities for RS, IS, and multi-spacecraft
studies. We summarise the achievements and highlight the challenges
faced during these investigations, many of which motivated the Solar
Orbiter mission. We present the new tools and techniques developed
by the MADAWG to support the science operations and the analysis of
the data from the many instruments on Solar Orbiter. Results:
This article reviews current modelling and tool developments that ease
the comparison of model results with RS and IS data made available
by current and upcoming missions. It also describes the modelling
strategy to support the science operations and subsequent exploitation
of Solar Orbiter data in order to maximise the scientific output
of the mission. Conclusions: The on-going community effort
presented in this paper has provided new models and tools necessary
to support mission operations as well as the science exploitation of
the Solar Orbiter data. The tools and techniques will no doubt evolve
significantly as we refine our procedure and methodology during the
first year of operations of this highly promising mission.

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Title: The Solar Orbiter Science Activity Plan. Translating solar
and heliospheric physics questions into action
Authors: Zouganelis, I.; De Groof, A.; Walsh, A. P.; Williams, D. R.;
Müller, D.; St Cyr, O. C.; Auchère, F.; Berghmans, D.; Fludra,
A.; Horbury, T. S.; Howard, R. A.; Krucker, S.; Maksimovic, M.;
Owen, C. J.; Rodríguez-Pacheco, J.; Romoli, M.; Solanki, S. K.;
Watson, C.; Sanchez, L.; Lefort, J.; Osuna, P.; Gilbert, H. R.;
Nieves-Chinchilla, T.; Abbo, L.; Alexandrova, O.; Anastasiadis, A.;
Andretta, V.; Antonucci, E.; Appourchaux, T.; Aran, A.; Arge, C. N.;
Aulanier, G.; Baker, D.; Bale, S. D.; Battaglia, M.; Bellot Rubio,
L.; Bemporad, A.; Berthomier, M.; Bocchialini, K.; Bonnin, X.; Brun,
A. S.; Bruno, R.; Buchlin, E.; Büchner, J.; Bucik, R.; Carcaboso,
F.; Carr, R.; Carrasco-Blázquez, I.; Cecconi, B.; Cernuda Cangas, I.;
Chen, C. H. K.; Chitta, L. P.; Chust, T.; Dalmasse, K.; D'Amicis, R.;
Da Deppo, V.; De Marco, R.; Dolei, S.; Dolla, L.; Dudok de Wit, T.;
van Driel-Gesztelyi, L.; Eastwood, J. P.; Espinosa Lara, F.; Etesi,
L.; Fedorov, A.; Félix-Redondo, F.; Fineschi, S.; Fleck, B.; Fontaine,
D.; Fox, N. J.; Gandorfer, A.; Génot, V.; Georgoulis, M. K.; Gissot,
S.; Giunta, A.; Gizon, L.; Gómez-Herrero, R.; Gontikakis, C.; Graham,
G.; Green, L.; Grundy, T.; Haberreiter, M.; Harra, L. K.; Hassler,
D. M.; Hirzberger, J.; Ho, G. C.; Hurford, G.; Innes, D.; Issautier,
K.; James, A. W.; Janitzek, N.; Janvier, M.; Jeffrey, N.; Jenkins,
J.; Khotyaintsev, Y.; Klein, K. -L.; Kontar, E. P.; Kontogiannis,
I.; Krafft, C.; Krasnoselskikh, V.; Kretzschmar, M.; Labrosse, N.;
Lagg, A.; Landini, F.; Lavraud, B.; Leon, I.; Lepri, S. T.; Lewis,
G. R.; Liewer, P.; Linker, J.; Livi, S.; Long, D. M.; Louarn, P.;
Malandraki, O.; Maloney, S.; Martinez-Pillet, V.; Martinovic, M.;
Masson, A.; Matthews, S.; Matteini, L.; Meyer-Vernet, N.; Moraitis,
K.; Morton, R. J.; Musset, S.; Nicolaou, G.; Nindos, A.; O'Brien,
H.; Orozco Suarez, D.; Owens, M.; Pancrazzi, M.; Papaioannou, A.;
Parenti, S.; Pariat, E.; Patsourakos, S.; Perrone, D.; Peter, H.;
Pinto, R. F.; Plainaki, C.; Plettemeier, D.; Plunkett, S. P.; Raines,
J. M.; Raouafi, N.; Reid, H.; Retino, A.; Rezeau, L.; Rochus, P.;
Rodriguez, L.; Rodriguez-Garcia, L.; Roth, M.; Rouillard, A. P.;
Sahraoui, F.; Sasso, C.; Schou, J.; Schühle, U.; Sorriso-Valvo, L.;
Soucek, J.; Spadaro, D.; Stangalini, M.; Stansby, D.; Steller, M.;
Strugarek, A.; Štverák, Š.; Susino, R.; Telloni, D.; Terasa, C.;
Teriaca, L.; Toledo-Redondo, S.; del Toro Iniesta, J. C.; Tsiropoula,
G.; Tsounis, A.; Tziotziou, K.; Valentini, F.; Vaivads, A.; Vecchio,
A.; Velli, M.; Verbeeck, C.; Verdini, A.; Verscharen, D.; Vilmer, N.;
Vourlidas, A.; Wicks, R.; Wimmer-Schweingruber, R. F.; Wiegelmann,
T.; Young, P. R.; Zhukov, A. N.
2020A&A...642A...3Z Altcode: 2020arXiv200910772Z
Solar Orbiter is the first space mission observing the solar plasma
both in situ and remotely, from a close distance, in and out of the
ecliptic. The ultimate goal is to understand how the Sun produces
and controls the heliosphere, filling the Solar System and driving
the planetary environments. With six remote-sensing and four in-situ
instrument suites, the coordination and planning of the operations are
essential to address the following four top-level science questions:
(1) What drives the solar wind and where does the coronal magnetic field
originate?; (2) How do solar transients drive heliospheric variability?;
(3) How do solar eruptions produce energetic particle radiation that
fills the heliosphere?; (4) How does the solar dynamo work and drive
connections between the Sun and the heliosphere? Maximising the
mission's science return requires considering the characteristics
of each orbit, including the relative position of the spacecraft
to Earth (affecting downlink rates), trajectory events (such
as gravitational assist manoeuvres), and the phase of the solar
activity cycle. Furthermore, since each orbit's science telemetry
will be downloaded over the course of the following orbit, science
operations must be planned at mission level, rather than at the level
of individual orbits. It is important to explore the way in which those
science questions are translated into an actual plan of observations
that fits into the mission, thus ensuring that no opportunities are
missed. First, the overarching goals are broken down into specific,
answerable questions along with the required observations and the
so-called Science Activity Plan (SAP) is developed to achieve this. The
SAP groups objectives that require similar observations into Solar
Orbiter Observing Plans, resulting in a strategic, top-level view of
the optimal opportunities for science observations during the mission
lifetime. This allows for all four mission goals to be addressed. In
this paper, we introduce Solar Orbiter's SAP through a series of
examples and the strategy being followed.

---------------------------------------------------------
Title: The Polarimetric and Helioseismic Imager on Solar Orbiter
Authors: Solanki, S. K.; del Toro Iniesta, J. C.; Woch, J.; Gandorfer,
A.; Hirzberger, J.; Alvarez-Herrero, A.; Appourchaux, T.; Martínez
Pillet, V.; Pérez-Grande, I.; Sanchis Kilders, E.; Schmidt, W.;
Gómez Cama, J. M.; Michalik, H.; Deutsch, W.; Fernandez-Rico, G.;
Grauf, B.; Gizon, L.; Heerlein, K.; Kolleck, M.; Lagg, A.; Meller, R.;
Müller, R.; Schühle, U.; Staub, J.; Albert, K.; Alvarez Copano, M.;
Beckmann, U.; Bischoff, J.; Busse, D.; Enge, R.; Frahm, S.; Germerott,
D.; Guerrero, L.; Löptien, B.; Meierdierks, T.; Oberdorfer, D.;
Papagiannaki, I.; Ramanath, S.; Schou, J.; Werner, S.; Yang, D.;
Zerr, A.; Bergmann, M.; Bochmann, J.; Heinrichs, J.; Meyer, S.;
Monecke, M.; Müller, M. -F.; Sperling, M.; Álvarez García, D.;
Aparicio, B.; Balaguer Jiménez, M.; Bellot Rubio, L. R.; Cobos
Carracosa, J. P.; Girela, F.; Hernández Expósito, D.; Herranz, M.;
Labrousse, P.; López Jiménez, A.; Orozco Suárez, D.; Ramos, J. L.;
Barandiarán, J.; Bastide, L.; Campuzano, C.; Cebollero, M.; Dávila,
B.; Fernández-Medina, A.; García Parejo, P.; Garranzo-García, D.;
Laguna, H.; Martín, J. A.; Navarro, R.; Núñez Peral, A.; Royo, M.;
Sánchez, A.; Silva-López, M.; Vera, I.; Villanueva, J.; Fourmond,
J. -J.; de Galarreta, C. Ruiz; Bouzit, M.; Hervier, V.; Le Clec'h,
J. C.; Szwec, N.; Chaigneau, M.; Buttice, V.; Dominguez-Tagle, C.;
Philippon, A.; Boumier, P.; Le Cocguen, R.; Baranjuk, G.; Bell,
A.; Berkefeld, Th.; Baumgartner, J.; Heidecke, F.; Maue, T.; Nakai,
E.; Scheiffelen, T.; Sigwarth, M.; Soltau, D.; Volkmer, R.; Blanco
Rodríguez, J.; Domingo, V.; Ferreres Sabater, A.; Gasent Blesa,
J. L.; Rodríguez Martínez, P.; Osorno Caudel, D.; Bosch, J.; Casas,
A.; Carmona, M.; Herms, A.; Roma, D.; Alonso, G.; Gómez-Sanjuan, A.;
Piqueras, J.; Torralbo, I.; Fiethe, B.; Guan, Y.; Lange, T.; Michel,
H.; Bonet, J. A.; Fahmy, S.; Müller, D.; Zouganelis, I.
2020A&A...642A..11S Altcode: 2019arXiv190311061S
 Aims: This paper describes the Polarimetric and Helioseismic
Imager on the Solar Orbiter mission (SO/PHI), the first magnetograph and
helioseismology instrument to observe the Sun from outside the Sun-Earth
line. It is the key instrument meant to address the top-level science
question: How does the solar dynamo work and drive connections between
the Sun and the heliosphere? SO/PHI will also play an important role
in answering the other top-level science questions of Solar Orbiter,
while hosting the potential of a rich return in further science. Methods: SO/PHI measures the Zeeman effect and the Doppler shift
in the Fe I 617.3 nm spectral line. To this end, the instrument
carries out narrow-band imaging spectro-polarimetry using a tunable
LiNbO3 Fabry-Perot etalon, while the polarisation modulation
is done with liquid crystal variable retarders. The line and the nearby
continuum are sampled at six wavelength points and the data are recorded
by a 2k × 2k CMOS detector. To save valuable telemetry, the raw data
are reduced on board, including being inverted under the assumption of
a Milne-Eddington atmosphere, although simpler reduction methods are
also available on board. SO/PHI is composed of two telescopes; one,
the Full Disc Telescope, covers the full solar disc at all phases of
the orbit, while the other, the High Resolution Telescope, can resolve
structures as small as 200 km on the Sun at closest perihelion. The high
heat load generated through proximity to the Sun is greatly reduced by
the multilayer-coated entrance windows to the two telescopes that allow
less than 4% of the total sunlight to enter the instrument, most of
it in a narrow wavelength band around the chosen spectral line. 
Results: SO/PHI was designed and built by a consortium having partners
in Germany, Spain, and France. The flight model was delivered to
Airbus Defence and Space, Stevenage, and successfully integrated into
the Solar Orbiter spacecraft. A number of innovations were introduced
compared with earlier space-based spectropolarimeters, thus allowing
SO/PHI to fit into the tight mass, volume, power and telemetry budgets
provided by the Solar Orbiter spacecraft and to meet the (e.g. thermal)
challenges posed by the mission's highly elliptical orbit.

---------------------------------------------------------
Title: PMI: The Photospheric Magnetic Field Imager
Authors: Staub, Jan; Fernandez-Rico, German; Gandorfer, Achim; Gizon,
Laurent; Hirzberger, Johann; Kraft, Stefan; Lagg, Andreas; Schou,
Jesper; Solanki, Sami K.; del Toro Iniesta, Jose Carlos; Wiegelmann,
Thomas; Woch, Joachim
2020JSWSC..10...54S Altcode:
We describe the design and the capabilities of the Photospheric Magnetic
field Imager (PMI), a compact and lightweight vector magnetograph,
which is being developed for ESA's Lagrange mission to the Lagrange
L5 point. After listing the design requirements and give a scientific
justification for them, we describe the technical implementation and
the design solution capable of fulfilling these requirements. This is
followed by a description of the hardware architecture as well as the
operations principle. An outlook on the expected performance concludes
the paper.

---------------------------------------------------------
Title: Helicity proxies from linear polarisation of solar active
regions
Authors: Prabhu, A.; Brandenburg, A.; Käpylä, M. J.; Lagg, A.
2020A&A...641A..46P Altcode: 2020arXiv200110884P
Context. The α effect is believed to play a key role in the
generation of the solar magnetic field. A fundamental test for its
significance in the solar dynamo is to look for magnetic helicity of
opposite signs both between the two hemispheres as well as between
small and large scales. However, measuring magnetic helicity is
compromised by the inability to fully infer the magnetic field vector
from observations of solar spectra, caused by what is known as the
π ambiguity of spectropolarimetric observations. Aims: We
decompose linear polarisation into parity-even and parity-odd E and B
polarisations, which are not affected by the π ambiguity. Furthermore,
we study whether the correlations of spatial Fourier spectra of B and
parity-even quantities such as E or temperature T are a robust proxy for
magnetic helicity of solar magnetic fields. Methods: We analysed
polarisation measurements of active regions observed by the Helioseismic
and Magnetic Imager on board the Solar Dynamics observatory. Theory
predicts the magnetic helicity of active regions to have, statistically,
opposite signs in the two hemispheres. We then computed the parity-odd
EB and TB correlations and tested for a systematic preference of
their sign based on the hemisphere of the active regions. 
Results: We find that: (i) EB and TB correlations are a reliable
proxy for magnetic helicity, when computed from linear polarisation
measurements away from spectral line cores; and (ii) E polarisation
reverses its sign close to the line core. Our analysis reveals that
Faraday rotation does not have a significant influence on the computed
parity-odd correlations. Conclusions: The EB decomposition of
linear polarisation appears to be a good proxy for magnetic helicity
independent of the π ambiguity. This allows us to routinely infer
magnetic helicity directly from polarisation measurements.

---------------------------------------------------------
Title: No universal connection between the vertical magnetic field
and the umbra-penumbra boundary in sunspots
Authors: Löptien, B.; Lagg, A.; van Noort, M.; Solanki, S. K.
2020A&A...639A.106L Altcode: 2020arXiv200602346L
Context. It has been reported that the boundary between the umbra and
the penumbra of sunspots occurs at a canonical value of the strength
of the vertical magnetic field, independently of the size of the
spot. This critical field strength is interpreted to be the threshold
for the onset of magnetoconvection. Aims: Here we investigate
the reasons why this criterion, also called the Jurčák criterion
in the literature, does not always identify the boundary between the
umbra and the penumbra. Methods: We performed a statistical
analysis of 23 sunspots observed with Hinode/SOT. We compared the
properties of the continuum intensity and the vertical magnetic
field between filaments and spines and how they vary between spots of
different sizes. Results: We find that the inner boundary of the
penumbra is not related to a universal value of the vertical magnetic
field. The properties of spines and filaments vary between spots of
different sizes. Both components are darker in larger spots and the
spines exhibit a stronger vertical magnetic field. These variations of
the properties of filaments and spines with the spot size are also the
reason for the reported invariance in the averaged vertical magnetic
field at 50% of the mean continuum intensity. Conclusions:
The formation of filaments and the onset of magnetoconvection are not
related to a canonical value of the strength of the vertical magnetic
field. The seemingly unique magnetic field strength is rather an effect
of the filling factor of spines and penumbral filaments.

---------------------------------------------------------
Title: Detection of the Strongest Magnetic Field in a Sunspot
Light Bridge
Authors: Castellanos Durán, J. S.; Lagg, Andreas; Solanki, Sami K.;
van Noort, Michiel
2020ApJ...895..129C Altcode: 2020arXiv200312078C; 2020ApJ...895..129D
Traditionally, the strongest magnetic fields on the Sun have been
measured in sunspot umbrae. More recently, however, much stronger
fields have been measured at the ends of penumbral filaments carrying
the Evershed and counter-Evershed flows. Superstrong fields have
also been reported within a light bridge separating two umbrae of
opposite polarities. We aim to accurately determine the strengths of the
strongest fields in a light bridge using an advanced inversion technique
and to investigate their detailed structure. We analyze observations
from the spectropolarimeter on board the Hinode spacecraft of the
active region AR 11967. The thermodynamic and magnetic configurations
are obtained by inverting the Stokes profiles using an inversion scheme
that allows multiple height nodes. Both the traditional 1D inversion
technique and the so-called 2D coupled inversions, which take into
account the point-spread function of the Hinode telescope, are used. We
find a compact structure with an area of 32.7 arcsec2 within
a bipolar light bridge with field strengths exceeding 5 kG, confirming
the strong fields in this light bridge reported in the literature. Two
regions associated with downflows of ∼5 km s-1 harbor
field strengths larger than 6.5 kG, covering a total area of 2.97
arcsec2. The maximum field strength found is 8.2 kG, which
is the largest ever observed field in a bipolar light bridge up to now.

---------------------------------------------------------
Title: Connecting the Wilson depression to the magnetic field
of sunspots
Authors: Löptien, B.; Lagg, A.; van Noort, M.; Solanki, S. K.
2020A&A...635A.202L Altcode: 2020arXiv200207484L
Context. In sunspots, the geometric height of continuum optical depth
unity is depressed compared to the quiet Sun. This so-called Wilson
depression is caused by the Lorentz force of the strong magnetic
field inside the spots. However, it is not understood in detail yet
how the Wilson depression is related to the strength and geometry
of the magnetic field or to other properties of the sunspot. 
Aims: We aim to study the dependence of the Wilson depression on the
properties of the magnetic field of the sunspots and how exactly the
magnetic field contributes to balancing the Wilson depression with
respect to the gas pressure of the surroundings of the spots. Methods: Our study is based on 24 spectropolarimetric scans of
12 individual sunspots performed with Hinode. We derived the Wilson
depression for each spot using both a recently developed method that
is based on minimizing the divergence of the magnetic field and an
approach that was developed earlier, which enforces an equilibrium
between the gas pressure and the magnetic pressure inside the spot and
the gas pressure in the quiet Sun, thus neglecting the influence of the
curvature force. We then performed a statistical analysis by comparing
the Wilson depression resulting from the two techniques with each other
and by relating them to various parameters of the sunspots, such as
their size or the strength of the magnetic field. Results: We
find that the Wilson depression becomes larger for spots with a stronger
magnetic field, but not as much as one would expect from the increased
magnetic pressure. This suggests that the curvature integral provides
an important contribution to the Wilson depression, particularly
for spots with a weak magnetic field. Our results indicate that the
geometry of the magnetic field in the penumbra is different between
spots with different strengths of the average umbral magnetic field.

---------------------------------------------------------
Title: Fast downflows in a chromospheric filament
Authors: Sowmya, K.; Lagg, A.; Solanki, S. K.; Castellanos Durán,
J. S.
2020IAUS..354..454S Altcode: 2019arXiv191206586S
An active region filament in the upper chromosphere is studied using
spectropolarimetric data in He i 10830 Å from the GREGOR telescope. A
Milne-Eddingon based inversion of the Unno-Rachkovsky equations is
used to retrieve the velocity and the magnetic field vector of the
region. The plasma velocity reaches supersonic values closer to the feet
of the filament barbs and coexist with a slow velocity component. Such
supersonic velocities result from the acceleration of the plasma as it
drains from the filament spine through the barbs. The line-of-sight
magnetic fields have strengths below 200 G in the filament spine and
in the filament barbs where fast downflows are located, their strengths
range between 100 - 700 G.

---------------------------------------------------------
Title: Superstrong photospheric magnetic fields in sunspot penumbrae
Authors: Siu-Tapia, A.; Lagg, A.; van Noort, M.; Rempel, M.; Solanki,
S. K.
2019A&A...631A..99S Altcode: 2019arXiv190913619S
Context. Recently, there have been some reports of unusually strong
photospheric magnetic fields (which can reach values of over 7 kG)
inferred from Hinode SOT/SP sunspot observations within penumbral
regions. These superstrong penumbral fields are even larger than the
strongest umbral fields on record and appear to be associated with
supersonic downflows. The finding of such fields has been controversial
since they seem to show up only when spatially coupled inversions
are performed. Aims: Here, we investigate and discuss the
reliability of those findings by studying in detail observed spectra
associated with particularly strong magnetic fields at the inner edge
of the penumbra of active region 10930. Methods: We applied
classical diagnostic methods and various inversions with different
model atmospheres to the observed Stokes profiles in two selected
pixels with superstrong magnetic fields, and compared the results
with a magnetohydrodynamic simulation of a sunspot whose penumbra
contains localized regions with strong fields (nearly 5 kG at τ = 1)
associated with supersonic downflows. Results: The different
inversions provide different results: while the SPINOR 2D inversions
consider a height-dependent single-component model and return B &gt;
7 kG and supersonic positive vLOS (corresponding to a
counter-Evershed flow), height-dependent two-component inversions
suggest the presence of an umbral component (almost at rest)
with field strengths ∼4 - 4.2 kG and a penumbral component with
vLOS ∼ 16 - 18 km s-1 and field strengths up
to ∼5.8 kG. Likewise, height-independent two-component inversions
find a solution for an umbral component and a strongly redshifted
(vLOS ∼ 15 - 17 km s-1) penumbral component
with B ∼ 4 kG. According to a Bayesian information criterion,
the inversions providing a better balance between the quality of
the fits and the number of free parameters considered by the models
are the height-independent two-component inversions, but they lie
only slightly above the SPINOR 2D inversions. Since it is expected
that the physical parameters all display considerable gradients with
height, as supported by magnetohydrodynamic (MHD) sunspot simulations,
the SPINOR 2D inversions are the preferred ones. Conclusions:
According to the MHD sunspot simulation analyzed here, the presence
of counter-Evershed flows in the photospheric penumbra can lead to
the necessary conditions for the observation of ∼5 kG fields at the
inner penumbra. Although a definite conclusion about the potential
existence of fields in excess of 7 kG cannot be given, their nature
could be explained (based on the simulation results) as the consequence
of the extreme dynamical effects introduced by highly supersonic
counter-Evershed flows (vLOS &gt; 10 km s-1
and up to ∼30 km s-1 according to SPINOR 2D). The latter
are much faster and more compressive downflows than those found in
the MHD simulations and therefore could lead to field intensification
up to considerably stronger fields. Also, a lower gas density would
lead to a deeper depression of the τ = 1 surface, making possible
the observation of deeper-lying stronger fields. The superstrong
magnetic fields are expected to be nearly force-free, meaning that
they can attain much larger strengths than expected when considering
only balance between magnetic pressure and the local gas pressure.

---------------------------------------------------------
Title: A comparison between solar plage and network properties
Authors: Buehler, D.; Lagg, A.; van Noort, M.; Solanki, S. K.
2019A&A...630A..86B Altcode: 2019arXiv190807464B
 Aims: We compare the properties of kG magnetic structures
in the solar network and in active region plage at high spatial
resolution. Methods: Our analysis used six SP scans of the solar
disc centre aboard Hinode SOT and inverted the obtained spectra of the
photospheric 6302 Å line pair using the 2D SPINOR code. Results:
Photospheric magnetic field concentrations in network and plage areas
are on average 1.5 kG strong with inclinations of 10° -20°, and have
&lt; 400 m s-1 internal and 2-3 km s-1 external
downflows. At the disc centre, the continuum intensity of magnetic
field concentrations in the network are on average 10% brighter than the
mean quiet Sun, whilst their plage counterparts are 3% darker. A more
detailed analysis revealed that all sizes of individual kG patches in
the network have 150 G higher field strengths on average, 5% higher
continuum contrasts, and 800 m s-1 faster surrounding
downflows than similarly sized patches in the plage. The speed of
the surrounding downflows also correlates with the patch area, and
patches containing pores can produce supersonic flows exceeding 11 km
s-1 in individual pixels. Furthermore, the magnetic canopies
of kG patches are on average 9° more horizontal in the plage compared
to the network. Conclusions: Most of the differences between the
network and plage are due to their different patch size distributions,
but the intrinsic differences between similarly sized patches likely
results from the modification of the convection photospheric convection
with increasing amounts of magnetic flux.

---------------------------------------------------------
Title: Performance Analysis of the SO/PHI Software Framework for
On-board Data Reduction
Authors: Albert, K.; Hirzberger, J.; Busse, D.; Rodríguez, J. Blanco;
Castellanos Duran, J. S.; Cobos Carrascosa, J. P.; Fiethe, B.;
Gandorfer, A.; Guan, Y.; Kolleck, M.; Lagg, A.; Lange, T.; Michalik,
H.; Solanki, S. K.; del Toro Iniesta, J. C.
2019ASPC..523..151A Altcode: 2019arXiv190508690A
The Polarimetric and Helioseismic Imager (PHI) is the first deep-space
solar spectropolarimeter, on-board the Solar Orbiter (SO) space
mission. It faces: stringent requirements on science data accuracy, a
dynamic environment, and severe limitations on telemetry volume. SO/PHI
overcomes these restrictions through on-board instrument calibration
and science data reduction, using dedicated firmware in FPGAs. This
contribution analyses the accuracy of a data processing pipeline by
comparing the results obtained with SO/PHI hardware to a reference
from a ground computer. The results show that for the analyzed pipeline
the error introduced by the firmware implementation is well below the
requirements of SO/PHI.

---------------------------------------------------------
Title: Using the infrared iron lines to probe solar subsurface
convection
Authors: Milić, I.; Smitha, H. N.; Lagg, A.
2019A&A...630A.133M Altcode: 2019arXiv190407306M
Context. Studying the properties of solar convection using
high-resolution spectropolarimetry began in the early 1990s with
the focus on observations in the visible wavelength regions. Its
extension to the infrared (IR) remains largely unexplored. 
Aims: The IR iron lines around 15 600 Å, most commonly known for
their high magnetic sensitivity, also have a non-zero response to
line-of-sight (LOS) velocity below log(τ) = 0.0. In this paper we
explore the possibility of using these lines to measure subsurface
convective velocities. Methods: By assuming a snapshot of a
three-dimensional magnetohydrodynamic simulation to represent the quiet
Sun, we investigate how well the iron IR lines can reproduce the LOS
velocity in the cube and to what depth. We use the recently developed
spectropolarimetric inversion code SNAPI and discuss the optimal node
placements for the retrieval of reliable results from these spectral
lines. Results: We find that the IR iron lines can measure the
convective velocities down to log(τ) = 0.5, below the photosphere,
not only at the original resolution of the cube, but also when degraded
with a reasonable spectral and spatial PSF and stray light. Instead, the
commonly used Fe I 6300 Å line pair performs significantly worse. Conclusions: Our investigation reveals that the IR iron lines can
probe the subsurface convection in the solar photosphere. This paper
is a first step towards exploiting this diagnostic potential.

---------------------------------------------------------
Title: Moving Magnetic Features around a Pore
Authors: Kaithakkal, A.; Riethmueller, T.; Solanki, S. K.; Lagg, A.
2019ASPC..526..307K Altcode:
Moving magnetic features (MMFs) are small-scale magnetic elements
observed to move radially outward from sunspots. Some studies have
reported the presence of MMFs around pores as well. We analyzed data
from SunriseII/IMaX observations obtained on 2013 June 12 between
23:39:10 and 23:55:37 UT. IMaX scanned the Fe I 5250.225 Å spectral
line at eight wavelength positions and recorded the full Stokes vector
at each of these positions. The field of view covered a large pore
(μ = 0.93) with pixel scale of 0″.055. MMFs of opposite (positive)
and same (negative) polarity as the pore were observed to stream
from the pore boundary. We carried out a statistical analysis of the
physical properties of MMFs and the main results are: 1) the number
of opposite polarity MMFs within 1.5 Mm from the pore border, when
they were first identified, is twice that of the same polarity MMFs. 2)
Only 11% of the chosen MMFs appear to be monopolar and they all have the
same polarity as the pore. 3) Majority of MMFs of both polarities move
away from the pore border with an average speed of 1.5 km/s. However,
they do not always follow a smooth radial track and some of them even
move in tangential direction to the pore. 4) MMFs of opposite polarity
show a preferential up-flow whereas those of the same polarity do not
show any preference. 5) MMFs of both polarities are characterized by
inclined fields. This work, presented in an oral contribution
at this Workshop, has been published on The Astrophysical Journal
Supplement Series (Kaithakkal et al. 2017).

---------------------------------------------------------
Title: Photospheric Magnetic Fields of the Trailing Sunspots in
Active Region NOAA 12396
Authors: Verma, M.; Balthasar, H.; Denker, C.; Böhm, F.; Fischer,
C. E.; Kuckein, C.; González Manrique, S. J.; Sobotka, M.; Bello
González, N.; Diercke, A.; Berkefeld, T.; Collados, M.; Feller, A.;
Hofmann, A.; Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Pastor Yabar,
A.; Rezaei, R.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth,
M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier, K.; Volkmer,
R.; von der Lühe, O.; Waldmann, T.
2019ASPC..526..291V Altcode: 2018arXiv180507752V
The solar magnetic field is responsible for all aspects of solar
activity. Sunspots are the main manifestation of the ensuing solar
activity. Combining high-resolution and synoptic observations has
the ambition to provide a comprehensive description of the sunspot
growth and decay processes. Active region NOAA 12396 emerged on 2015
August 3 and was observed three days later with the 1.5-meter GREGOR
solar telescope on 2015 August 6. High-resolution spectropolarimetric
data from the GREGOR Infrared Spectrograph (GRIS) are obtained in the
photospheric lines Si I λ1082.7 nm and Ca I λ1083.9 nm, together
with the chromospheric He I λ1083.0 nm triplet. These near-infrared
spectropolarimetric observations were complemented by synoptic
line-of-sight magnetograms and continuum images of the Helioseismic
and Magnetic Imager (HMI) and EUV images of the Atmospheric Imaging
Assembly (AIA) on board the Solar Dynamics Observatory (SDO).

---------------------------------------------------------
Title: Measuring the Wilson depression of sunspots using the
divergence-free condition of the magnetic field vector
Authors: Löptien, B.; Lagg, A.; van Noort, M.; Solanki, S. K.
2018A&A...619A..42L Altcode: 2018arXiv180806867L
Context. The Wilson depression is the difference in geometric height of
unit continuum optical depth between the sunspot umbra and the quiet
Sun. Measuring the Wilson depression is important for understanding
the geometry of sunspots. Current methods suffer from systematic
effects or need to make assumptions on the geometry of the magnetic
field. This leads to large systematic uncertainties of the derived
Wilson depressions. Aims: We aim to develop a robust method
for deriving the Wilson depression that only requires the information
about the magnetic field that is accessible from spectropolarimetry,
and that does not rely on assumptions on the geometry of sunspots
or on their magnetic field. Methods: Our method is based on
minimizing the divergence of the magnetic field vector derived from
spectropolarimetric observations. We have focused on large spatial
scales only in order to reduce the number of free parameters. 
Results: We tested the performance of our method using synthetic Hinode
data derived from two sunspot simulations. We find that the maximum and
the umbral averaged Wilson depression for both spots determined with
our method typically lies within 100 km of the true value obtained
from the simulations. In addition, we applied the method to Hinode
observations of a sunspot. The derived Wilson depression (∼600 km) is
consistent with results typically obtained from the Wilson effect. We
also find that the Wilson depression obtained from using horizontal
force balance gives 110-180 km smaller Wilson depressions than both,
what we find and what we deduce directly from the simulations. This
suggests that the magnetic pressure and the magnetic curvature force
contribute to the Wilson depression by a similar amount.

---------------------------------------------------------
Title: SOPHISM: Software Instrument Simulator
Authors: Blanco Rodríguez, J.; del Toro Iniesta, J. C.; Orozco
Suárez, D.; Martínez Pillet, V.; Bonet, J. A.; Feller, A.;
Hirzberger, J.; Lagg, A.; Piqueras, J.; Gasent Blesa, J. L.
2018ascl.soft10017B Altcode:
SOPHISM models astronomical instrumentation from the entrance
of the telescope to data acquisition at the detector, along with
software blocks dealing with, for example, demodulation, inversion,
and compression. The code performs most analyses done with light
in astronomy, such as differential photometry, spectroscopy, and
polarimetry. The simulator offers flexibility and implementation of new
effects and subsystems, making it user-adaptable for a wide variety
of instruments. SOPHISM can be used for all stages of instrument
definition, design, operation, and lifetime tracking evaluation.

---------------------------------------------------------
Title: Temporal evolution of arch filaments as seen in He I 10 830 Å
Authors: González Manrique, S. J.; Kuckein, C.; Collados, M.; Denker,
C.; Solanki, S. K.; Gömöry, P.; Verma, M.; Balthasar, H.; Lagg,
A.; Diercke, A.
2018A&A...617A..55G Altcode: 2018arXiv180700728G
 Aims: We study the evolution of an arch filament system (AFS)
and of its individual arch filaments to learn about the processes
occurring in them. Methods: We observed the AFS at the
GREGOR solar telescope on Tenerife at high cadence with the very
fast spectroscopic mode of the GREGOR Infrared Spectrograph (GRIS)
in the He I 10 830 Å spectral range. The He I triplet profiles
were fitted with analytic functions to infer line-of-sight (LOS)
velocities to follow plasma motions within the AFS. Results:
We tracked the temporal evolution of an individual arch filament
over its entire lifetime, as seen in the He I 10 830 Å triplet. The
arch filament expanded in height and extended in length from 13″ to
21″. The lifetime of this arch filament is about 30 min. About 11
min after the arch filament is seen in He I, the loop top starts to
rise with an average Doppler velocity of 6 km s-1. Only two
minutes later, plasma drains down with supersonic velocities towards
the footpoints reaching a peak velocity of up to 40 km s-1
in the chromosphere. The temporal evolution of He I 10 830 Å profiles
near the leading pore showed almost ubiquitous dual red components of
the He I triplet, indicating strong downflows, along with material
nearly at rest within the same resolution element during the whole
observing time. Conclusions: We followed the arch filament as it
carried plasma during its rise from the photosphere to the corona. The
material then drained toward the photosphere, reaching supersonic
velocities, along the legs of the arch filament. Our observational
results support theoretical AFS models and aids in improving future
models. The movie associated to Fig. 3 is available at <A
href="https://www.aanda.org/10.1051/0004-6361/201832684/olm">https://www.aanda.org/</A>

---------------------------------------------------------
Title: SOPHISM: An End-to-end Software Instrument Simulator
Authors: Blanco Rodríguez, J.; del Toro Iniesta, J. C.; Orozco
Suárez, D.; Martínez Pillet, V.; Bonet, J. A.; Feller, A.;
Hirzberger, J.; Lagg, A.; Piqueras, J.; Gasent Blesa, J. L.
2018ApJS..237...35B Altcode:
We present a software simulator for the modeling of astronomical
instrumentation, which includes platform effects and software
processing. It is an end-to-end simulator, from the entrance of
the telescope to the data acquisition at the detector, along with
software blocks dealing, e.g., with demodulation, inversion, and
compression. Developed following the Solar Orbiter/Polarimetric
and Helioseismic Imager (SO/PHI) instrument, it comprises elements
such as a filtergraph, polarimetric modulator, detector, vibrations,
and accumulations. Through these, the simulator performs most of the
analyses that can be done with light in astronomy, such as differential
photometry, spectroscopy, and polarimetry. The simulator is coded
with high flexibility and ease of implementation of new effects and
subsystems. Thus, it allows for the user to adapt it to a wide variety
of instruments, even not exclusively solar ones, as illustrated with
an example of application to a night-time observation. The simulator
can provide support in the phase of instrument design and help assess
tolerances and test solutions to underperformances arising during the
instrument operations. All this makes SOPHISM a very valuable tool
for all the stages of astronomical instrument definition, design,
operation, and lifetime tracking evaluation.

---------------------------------------------------------
Title: Bihelical Spectrum of Solar Magnetic Helicity and Its Evolution
Authors: Singh, Nishant K.; Käpylä, Maarit J.; Brandenburg, Axel;
Käpylä, Petri J.; Lagg, Andreas; Virtanen, Ilpo
2018ApJ...863..182S Altcode: 2018arXiv180404994S
Using a recently developed two-scale formalism to determine the
magnetic helicity spectrum, we analyze synoptic vector magnetograms
built with data from the Vector Spectromagnetograph instrument on the
Synoptic Optical Long-term Investigations of the Sun telescope during
2010 January-2016 July. In contrast to an earlier study using only
three Carrington rotations (CRs), our analysis includes 74 synoptic
CR maps. We recover here bihelical spectra at different phases of
solar cycle 24, where the net magnetic helicity in the majority of the
data is consistent with a large-scale dynamo with helical turbulence
operating in the Sun. More than 20% of the analyzed maps, however,
show violations of the expected sign rule.

---------------------------------------------------------
Title: Getting Ready for the Third Science Flight of SUNRISE
Authors: Barthol, Peter; Katsukawa, Yukio; Lagg, Andreas; Solanki,
Sami K.; Kubo, Masahito; Riethmueller, Tino; Martínez Pillet,
Valentin; Gandorfer, Achim; Feller, Alex; Berkefeld, . Thomas; Orozco
Suárez, David; Del Toro Iniesta, Jose Carlos; Bernasconi, Pietro;
Álvarez-Herrero, Alberto; Quintero Noda, Carlos
2018cosp...42E.215B Altcode:
SUNRISE is a balloon-borne, stratospheric solar observatory dedicated
to the investigation of the structure and dynamics of the Sun's
magnetic field and its interaction with convective plasma flows and
waves. The previous science flights of SUNRISE in 2009 and 2013 have
led to many new scientific results, so far described in around 90
refereed publications. This success has shown the huge potential of the
SUNRISE concept and the recovery of the largely intact payload offers
the opportunity for a third flight.The scientific instrumentation of
SUNRISE 3 will have extended capabilities in particular to measure
magnetic fields, plasma velocities and temperatures with increased
sensitivity and over a larger height range in the solar atmosphere, from
the convectively dominated photosphere up to the still poorly understood
chromosphere. The latter is the key interaction region between magnetic
field, waves and radiation and plays a central role in transporting
energy to the outer layers of the solar atmosphere including the
corona.SUNRISE 3 will carry 2 new grating-based spectro-polarimeters
with slit-scanning and context imaging with slitjaw cameras. The
SUNRISE UV Spectro-polarimeter and Imager (SUSI) will explore the rich
near-UV range between 300 nm and 430 nm which is poorly accessible
from the ground. The SUNRISE Chromospheric Infrared spectro-Polarimeter
(SCIP) will sample 2 spectral windows in the near-infrared, containing
many spectral lines highly sensitive to magnetic fields at different
formation heights. In addition to the two new instruments the Imaging
Magnetograph eXperiment (IMaX), an etalon-based tunable filtergraph and
spectro-polarimeter flown on both previous missions, will be upgraded
to IMaX+, enhancing its cadence and giving access to 2 spectral lines
in the visible spectral range. All three instruments will allow
investigating both the photosphere and the chromosphere and will
ideally complement each other in terms of sensitivity, height coverage
and resolution.A new gondola with a sophisticated attitude control
system including roll damping will provide improved pointing/tracking
performance. Upgraded image stabilization with higher bandwidth will
further reduce residual jitter, maximizing the quality of the science
data.SUNRISE 3 is a joint project of the German Max-Planck-Institut für
Sonnensystemforschung together with the Spanish SUNRISE consortium, the
Johns Hopkins University Applied Physics Laboratory, USA, the German
Kiepenheuer Institut für Sonnenphysik, the National Astronomical
Observatory of Japan and the Japan Aerospace eXploraion Agency (JAXA).

---------------------------------------------------------
Title: Evershed and Counter-Evershed Flows in Sunspot MHD Simulations
Authors: Siu-Tapia, A. L.; Rempel, M.; Lagg, A.; Solanki, S. K.
2018ApJ...852...66S Altcode: 2017arXiv171201202S
There have been a few reports in the literature of counter-Evershed
flows observed in well-developed sunspot penumbrae, i.e., flows
directed toward the umbra along penumbral filaments. Here, we
investigate the driving forces of such counter-Evershed flows in a
radiative magnetohydrodynamic simulation of a sunspot, and compare
them to the forces acting on the normal Evershed flow. The simulation
covers a timespan of 100 solar hours and generates an Evershed outflow
exceeding 8 km s-1 in the penumbra along radially aligned
filaments where the magnetic field is almost horizontal. Additionally,
the simulation produces a fast counter-Evershed flow (i.e., an inflow
near τ =1) in some regions within the penumbra, reaching peak flow
speeds of ∼12 km s-1. The counter-Evershed flows are
transient and typically last a few hours before they turn into outflows
again. By using the kinetic energy equation and evaluating its various
terms in the simulation box, we found that the Evershed flow occurs
due to overturning convection in a strongly inclined magnetic field,
while the counter-Evershed flows can be well-described as siphon flows.

---------------------------------------------------------
Title: Normal and counter Evershed flows in the photospheric penumbra
of a sunspot. SPINOR 2D inversions of Hinode-SOT/SP observations
Authors: Siu-Tapia, A.; Lagg, A.; Solanki, S. K.; van Noort, M.;
Jurčák, J.
2017A&A...607A..36S Altcode: 2017arXiv170907386S
Context. The Evershed effect, a nearly horizontal outflow of material
seen in the penumbrae of sunspots in the photospheric layers, is a
common characteristic of well-developed penumbrae, but is still not well
understood. Even less is known about photospheric horizontal inflows in
the penumbra, also known as counter Evershed flows. Aims: Here we
present a rare feature observed in the penumbra of the main sunspot of
AR NOAA 10930. This spot displays the normal Evershed outflow in most
of the penumbra, but harbors a fast photospheric inflow of material
over a large sector of the disk-center penumbra. We investigate the
driving forces of both, the normal and the counter Evershed flows. Methods: We invert the spectropolarimetric data from Hinode SOT/SP
using the spatially coupled version of the SPINOR inversion code,
which allows us to derive height-dependent maps of the relevant
physical parameters in the sunspot. These maps show considerable fine
structure. Similarities and differences between the normal Evershed
outflow and the counter Evershed flow are investigated. Results:
In both the normal and the counter Evershed flows, the material flows
from regions with field strengths of the order of 1.5-2 kG to regions
with stronger fields. The sources and sinks of both penumbral flows
display opposite field polarities, with the sinks (tails of filaments)
harboring local enhancements in temperature, which are nonetheless
colder than their sources (heads of filaments). Conclusions:
The anti-correlation of the gradients in the temperature and magnetic
pressure between the endpoints of the filaments from the two distinct
penumbral regions is compatible with both the convective driver and
the siphon flow scenarios. A geometrical scale of the parameters is
necessary to determine which is the dominant force driving the flows.

---------------------------------------------------------
Title: Flows along arch filaments observed in the GRIS `very fast
spectroscopic mode'
Authors: González Manrique, S. J.; Denker, C.; Kuckein, C.; Pastor
Yabar, A.; Collados, M.; Verma, M.; Balthasar, H.; Diercke, A.;
Fischer, C. E.; Gömöry, P.; Bello González, N.; Schlichenmaier,
R.; Cubas Armas, M.; Berkefeld, T.; Feller, A.; Hoch, S.; Hofmann,
A.; Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Schmidt, D.; Schmidt,
W.; Sigwarth, M.; Sobotka, M.; Solanki, S. K.; Soltau, D.; Staude,
J.; Strassmeier, K. G.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
2017IAUS..327...28G Altcode: 2017arXiv170102206G
A new generation of solar instruments provides improved spectral,
spatial, and temporal resolution, thus facilitating a better
understanding of dynamic processes on the Sun. High-resolution
observations often reveal multiple-component spectral line profiles,
e.g., in the near-infrared He i 10830 Å triplet, which provides
information about the chromospheric velocity and magnetic fine
structure. We observed an emerging flux region, including two small
pores and an arch filament system, on 2015 April 17 with the `very
fast spectroscopic mode' of the GREGOR Infrared Spectrograph (GRIS)
situated at the 1.5-meter GREGOR solar telescope at Observatorio del
Teide, Tenerife, Spain. We discuss this method of obtaining fast (one
per minute) spectral scans of the solar surface and its potential to
follow dynamic processes on the Sun. We demonstrate the performance
of the `very fast spectroscopic mode' by tracking chromospheric
high-velocity features in the arch filament system.

---------------------------------------------------------
Title: Measurements of Photospheric and Chromospheric Magnetic Fields
Authors: Lagg, Andreas; Lites, Bruce; Harvey, Jack; Gosain, Sanjay;
Centeno, Rebecca
2017SSRv..210...37L Altcode: 2015arXiv151006865L; 2015SSRv..tmp..115L
The Sun is replete with magnetic fields, with sunspots, pores
and plage regions being their most prominent representatives on
the solar surface. But even far away from these active regions,
magnetic fields are ubiquitous. To a large extent, their importance
for the thermodynamics in the solar photosphere is determined by the
total magnetic flux. Whereas in low-flux quiet Sun regions, magnetic
structures are shuffled around by the motion of granules, the high-flux
areas like sunspots or pores effectively suppress convection, leading
to a temperature decrease of up to 3000 K. The importance of magnetic
fields to the conditions in higher atmospheric layers, the chromosphere
and corona, is indisputable. Magnetic fields in both active and
quiet regions are the main coupling agent between the outer layers
of the solar atmosphere, and are therefore not only involved in the
structuring of these layers, but also for the transport of energy from
the solar surface through the corona to the interplanetary space. Consequently, inference of magnetic fields in the photosphere, and
especially in the chromosphere, is crucial to deepen our understanding
not only for solar phenomena such as chromospheric and coronal
heating, flares or coronal mass ejections, but also for fundamental
physical topics like dynamo theory or atomic physics. In this review,
we present an overview of significant advances during the last decades
in measurement techniques, analysis methods, and the availability of
observatories, together with some selected results. We discuss the
problems of determining magnetic fields at smallest spatial scales,
connected with increasing demands on polarimetric sensitivity and
temporal resolution, and highlight some promising future developments
for their solution.

---------------------------------------------------------
Title: Three-dimensional magnetic structure of a sunspot: Comparison
of the photosphere and upper chromosphere
Authors: Joshi, Jayant; Lagg, Andreas; Hirzberger, Johann; Solanki,
Sami K.
2017A&A...604A..98J Altcode: 2017arXiv170508404J
 Aims: We investigate the magnetic field of a sunspot in the
upper chromosphere and compare it to the photospheric properties
of the field. Methods: We observed the main leading sunspot
of the active region NOAA 11124 during two days with the Tenerife
Infrared Polarimeter-2 (TIP-2) mounted at the German Vacuum Tower
Telescope (VTT). Through inversion of Stokes spectra of the He I
triplet at 10 830 Å, we obtained the magnetic field vector of the
upper chromosphere. For comparison with the photosphere, we applied
height-dependent inversions of the Si I 10 827.1 Å and Ca I 10 833.4 Å
lines. Results: We found that the umbral magnetic field strength
in the upper chromosphere is lower by a factor of 1.30-1.65 compared
to the photosphere. The magnetic field strength of the umbra decreases
from the photosphere toward the upper chromosphere by an average rate of
0.5-0.9 G km-1. The difference in the magnetic field strength
between both atmospheric layers steadily decreases from the sunspot
center to the outer boundary of the sunspot; the field, in particular
its horizontal component, is stronger in the chromopshere outside the
spot and this is suggestive of a magnetic canopy. The sunspot displays
a twist that on average is similar in the two layers. However, the
differential twist between the photosphere and chromosphere increases
rapidly toward the outer penumbral boundary. The magnetic field
vector is more horizontal with respect to the solar surface by roughly
5-20° in the photosphere compared to the upper chromosphere. Above
a lightbridge, the chromospheric magnetic field is equally strong as
that in the umbra, whereas the field of the lightbridge is weaker than
its surroundings in the photosphere by roughly 1 kG. This suggests a
cusp-like magnetic field structure above the lightbridge.

---------------------------------------------------------
Title: Extended Subadiabatic Layer in Simulations of Overshooting
Convection
Authors: Käpylä, Petri J.; Rheinhardt, Matthias; Brandenburg, Axel;
Arlt, Rainer; Käpylä, Maarit J.; Lagg, Andreas; Olspert, Nigul;
Warnecke, Jörn
2017ApJ...845L..23K Altcode: 2017arXiv170306845K
We present numerical simulations of hydrodynamic overshooting convection
in local Cartesian domains. We find that a substantial fraction
of the lower part of the convection zone (CZ) is stably stratified
according to the Schwarzschild criterion while the enthalpy flux is
outward directed. This occurs when the heat conduction profile at the
bottom of the CZ is smoothly varying, based either on a Kramers-like
opacity prescription as a function of temperature and density or a
static profile of a similar shape. We show that the subadiabatic layer
arises due to nonlocal energy transport by buoyantly driven downflows
in the upper parts of the CZ. Analysis of the force balance of the
upflows and downflows confirms that convection is driven by cooling
at the surface. We find that the commonly used prescription for the
convective enthalpy flux being proportional to the negative entropy
gradient does not hold in the stably stratified layers where the flux is
positive. We demonstrate the existence of a non-gradient contribution
to the enthalpy flux, which is estimated to be important throughout
the convective layer. A quantitative analysis of downflows indicates
a transition from a tree-like structure where smaller downdrafts merge
into larger ones in the upper parts to a structure in the deeper parts
where a height-independent number of strong downdrafts persist. This
change of flow topology occurs when a substantial subadiabatic layer
is present in the lower part of the CZ.

---------------------------------------------------------
Title: Erratum: Morphological Properties of
Slender CaII H Fibrils Observed by sunrise II (<A
href="http://doi.org/10.3847/1538-4365/229/1/6">ApJS 229, 1, 6</A>)
Authors: Gafeira, R.; Lagg, A.; Solanki, S. K.; Jafarzadeh, S.;
van Noort, M.; Barthol, P.; Blanco Rodríguez, J.; del Toro Iniesta,
J. C.; Gandorfer, A.; Gizon, L.; Hirzberger, J.; Knölker, M.; Orozco
Suárez, D.; Riethmüller, T. L.; Schmidt, W.
2017ApJS..230...11G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Second Flight of the Sunrise Balloon-borne Solar
Observatory: Overview of Instrument Updates, the Flight, the Data,
and First Results
Authors: Solanki, S. K.; Riethmüller, T. L.; Barthol, P.; Danilovic,
S.; Deutsch, W.; Doerr, H. -P.; Feller, A.; Gandorfer, A.; Germerott,
D.; Gizon, L.; Grauf, B.; Heerlein, K.; Hirzberger, J.; Kolleck, M.;
Lagg, A.; Meller, R.; Tomasch, G.; van Noort, M.; Blanco Rodríguez,
J.; Gasent Blesa, J. L.; Balaguer Jiménez, M.; Del Toro Iniesta,
J. C.; López Jiménez, A. C.; Orozco Suarez, D.; Berkefeld, T.;
Halbgewachs, C.; Schmidt, W.; Álvarez-Herrero, A.; Sabau-Graziati,
L.; Pérez Grande, I.; Martínez Pillet, V.; Card, G.; Centeno, R.;
Knölker, M.; Lecinski, A.
2017ApJS..229....2S Altcode: 2017arXiv170101555S
The Sunrise balloon-borne solar observatory, consisting of a 1 m
aperture telescope that provides a stabilized image to a UV filter
imager and an imaging vector polarimeter, carried out its second science
flight in 2013 June. It provided observations of parts of active regions
at high spatial resolution, including the first high-resolution images
in the Mg II k line. The obtained data are of very high quality, with
the best UV images reaching the diffraction limit of the telescope
at 3000 Å after Multi-Frame Blind Deconvolution reconstruction
accounting for phase-diversity information. Here a brief update is
given of the instruments and the data reduction techniques, which
includes an inversion of the polarimetric data. Mainly those aspects
that evolved compared with the first flight are described. A tabular
overview of the observations is given. In addition, an example time
series of a part of the emerging active region NOAA AR 11768 observed
relatively close to disk center is described and discussed in some
detail. The observations cover the pores in the trailing polarity of
the active region, as well as the polarity inversion line where flux
emergence was ongoing and a small flare-like brightening occurred in
the course of the time series. The pores are found to contain magnetic
field strengths ranging up to 2500 G, and while large pores are clearly
darker and cooler than the quiet Sun in all layers of the photosphere,
the temperature and brightness of small pores approach or even exceed
those of the quiet Sun in the upper photosphere.

---------------------------------------------------------
Title: Vertical magnetic field gradient in the photospheric layers
of sunspots
Authors: Joshi, Jayant; Lagg, Andreas; Hirzberger, Johann; Solanki,
Sami K.; Tiwari, Sanjiv K.
2017A&A...599A..35J Altcode: 2016arXiv161000500J
 Aims: We investigate the vertical gradient of the magnetic
field of sunspots in the photospheric layer. Methods:
Independent observations were obtained with the Solar Optical
Telescope/Spectropolarimeter (SOT/SP) on board the Hinode spacecraft and
with the Tenrife Infrared Polarimeter-2 (TIP-2) mounted at the German
Vacuum Tower Telescope (VTT). We apply state-of-the-art inversion
techniques to both data sets to retrieve the magnetic field and the
corresponding vertical gradient along with other atmospheric parameters
in the solar photosphere. Results: In the sunspot penumbrae we
detected patches of negative vertical gradients of the magnetic field
strength, I.e., the magnetic field strength decreases with optical depth
in the photosphere. The negative gradient patches are located in the
inner and partly in the middle penumbrae in both data sets. From the
SOT/SP observations we found that the negative gradient patches are
restricted mainly to the deep photospheric layers and are concentrated
near the edges of the penumbral filaments. Magnetohydrodynamic (MHD)
simulations also show negative gradients in the inner penumbrae, also
at the locations of filaments. In the observations and the simulation
negative gradients of the magnetic field vs. optical depth dominate
at some radial distances in the penumbra. The negative gradient with
respect to optical depth in the inner penumbrae persists even after
averaging in the azimuthal direction in the observations and, to a
lesser extent, in the MHD simulations. If the gradients in the MHD
simulations are determined with respect to geometrical height, then
the azimuthal averages are always positive within the sunspot (above
log τ = 0), corresponding to magnetic field increasing with depth,
as generally expected. Conclusions: We interpret the observed
localized presence of negative vertical gradient of the magnetic
field strength in the observations as a consequence of stronger field
from spines expanding with height and closing above the weaker field
inter-spines. The presence of the negative gradients with respect
to optical depth after azimuthal averaging can be explained by two
different mechanisms: the high corrugation of equal optical depth
surfaces and the cancellation of polarized signal due to the presence
of unresolved opposite polarity patches in the deeper layers of the
penumbra.

---------------------------------------------------------
Title: Morphological Properties of Slender Ca II H Fibrils Observed
by SUNRISE II
Authors: Gafeira, R.; Lagg, A.; Solanki, S. K.; Jafarzadeh, S.;
van Noort, M.; Barthol, P.; Blanco Rodríguez, J.; del Toro Iniesta,
J. C.; Gandorfer, A.; Gizon, L.; Hirzberger, J.; Knölker, M.; Orozco
Suárez, D.; Riethmüller, T. L.; Schmidt, W.
2017ApJS..229....6G Altcode: 2016arXiv161200319G
We use seeing-free high spatial resolution Ca II H data obtained by
the SUNRISE observatory to determine properties of slender fibrils
in the lower solar chromosphere. In this work we use intensity images
taken with the SuFI instrument in the Ca II H line during the second
scientific flight of the SUNRISE observatory to identify and track
elongated bright structures. After identification, we analyze theses
structures to extract their morphological properties. We identify
598 slender Ca II H fibrils (SCFs) with an average width of around
180 km, length between 500 and 4000 km, average lifetime of ≈400
s, and average curvature of 0.002 arcsec-1. The maximum
lifetime of the SCFs within our time series of 57 minutes is ≈2000
s. We discuss similarities and differences of the SCFs with other
small-scale, chromospheric structures such as spicules of type I and
II, or Ca II K fibrils.

---------------------------------------------------------
Title: Oscillations on Width and Intensity of Slender Ca II H Fibrils
from Sunrise/SuFI
Authors: Gafeira, R.; Jafarzadeh, S.; Solanki, S. K.; Lagg, A.;
van Noort, M.; Barthol, P.; Blanco Rodríguez, J.; del Toro Iniesta,
J. C.; Gandorfer, A.; Gizon, L.; Hirzberger, J.; Knölker, M.; Orozco
Suárez, D.; Riethmüller, T. L.; Schmidt, W.
2017ApJS..229....7G Altcode: 2017arXiv170102801G
We report the detection of oscillations in slender Ca II H fibrils
(SCFs) from high-resolution observations acquired with the Sunrise
balloon-borne solar observatory. The SCFs show obvious oscillations in
their intensity, but also their width. The oscillatory behaviors are
investigated at several positions along the axes of the SCFs. A large
majority of fibrils show signs of oscillations in intensity. Their
periods and phase speeds are analyzed using a wavelet analysis. The
width and intensity perturbations have overlapping distributions
of the wave period. The obtained distributions have median values
of the period of 32 ± 17 s and 36 ± 25 s, respectively. We
find that the fluctuations of both parameters propagate in
the SCFs with speeds of {11}-11+49 km
s-1 and {15}-15+34 km s-1,
respectively. Furthermore, the width and intensity oscillations have a
strong tendency to be either in anti-phase or, to a smaller extent, in
phase. This suggests that the oscillations of both parameters are caused
by the same wave mode and that the waves are likely propagating. Taking
all the evidence together, the most likely wave mode to explain all
measurements and criteria is the fast sausage mode.

---------------------------------------------------------
Title: Moving Magnetic Features around a Pore
Authors: Kaithakkal, A. J.; Riethmüller, T. L.; Solanki, S. K.; Lagg,
A.; Barthol, P.; Gandorfer, A.; Gizon, L.; Hirzberger, J.; vanNoort,
M.; Blanco Rodríguez, J.; Del Toro Iniesta, J. C.; Orozco Suárez,
D.; Schmidt, W.; Martínez Pillet, V.; Knölker, M.
2017ApJS..229...13K Altcode: 2016arXiv160905664K
Spectropolarimetric observations from Sunrise/IMaX, obtained in 2013
June, are used for a statistical analysis to determine the physical
properties of moving magnetic features (MMFs) observed near a pore. MMFs
of the same and opposite polarity, with respect to the pore, are found
to stream from its border at an average speed of 1.3 km s-1
and 1.2 km s-1, respectively, with mainly same-polarity MMFs
found further away from the pore. MMFs of both polarities are found to
harbor rather weak, inclined magnetic fields. Opposite-polarity MMFs
are blueshifted, whereas same-polarity MMFs do not show any preference
for up- or downflows. Most of the MMFs are found to be of sub-arcsecond
size and carry a mean flux of ∼1.2 × 1017 Mx.

---------------------------------------------------------
Title: Measurements of photospheric magnetic fields
Authors: Lagg, Andreas
2017psio.confE..31L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Slipping reconnection in a solar flare observed in high
resolution with the GREGOR solar telescope
Authors: Sobotka, M.; Dudík, J.; Denker, C.; Balthasar, H.; Jurčák,
J.; Liu, W.; Berkefeld, T.; Collados Vera, M.; Feller, A.; Hofmann,
A.; Kneer, F.; Kuckein, C.; Lagg, A.; Louis, R. E.; von der Lühe, O.;
Nicklas, H.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth,
M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier, K. G.;
Volkmer, R.; Waldmann, T.
2016A&A...596A...1S Altcode: 2016arXiv160500464S
A small flare ribbon above a sunspot umbra in active region 12205 was
observed on November 7, 2014, at 12:00 UT in the blue imaging channel
of the 1.5 m GREGOR telescope, using a 1 Å Ca II H interference
filter. Context observations from the Atmospheric Imaging Assembly
(AIA) onboard the Solar Dynamics Observatory (SDO), the Solar Optical
Telescope (SOT) onboard Hinode, and the Interface Region Imaging
Spectrograph (IRIS) show that this ribbon is part of a larger one
that extends through the neighboring positive polarities and also
participates in several other flares within the active region. We
reconstructed a time series of 140 s of Ca II H images by means of the
multiframe blind deconvolution method, which resulted in spatial and
temporal resolutions of 0.1″ and 1 s. Light curves and horizontal
velocities of small-scale bright knots in the observed flare ribbon
were measured. Some knots are stationary, but three move along the
ribbon with speeds of 7-11 km s-1. Two of them move in the
opposite direction and exhibit highly correlated intensity changes,
which provides evidence of a slipping reconnection at small spatial
scales. Movies associated to Figs. 1 and 2 are available at <A
href="http://www.aanda.org/10.1051/0004-6361/201527966/olm">http://www.aanda.org</A>

---------------------------------------------------------
Title: Deep probing of the photospheric sunspot penumbra: no evidence
of field-free gaps
Authors: Borrero, J. M.; Asensio Ramos, A.; Collados, M.;
Schlichenmaier, R.; Balthasar, H.; Franz, M.; Rezaei, R.; Kiess, C.;
Orozco Suárez, D.; Pastor Yabar, A.; Berkefeld, T.; von der Lühe,
O.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Soltau, D.; Volkmer, R.;
Waldmann, T.; Denker, C.; Hofmann, A.; Staude, J.; Strassmeier, K. G.;
Feller, A.; Lagg, A.; Solanki, S. K.; Sobotka, M.; Nicklas, H.
2016A&A...596A...2B Altcode: 2016arXiv160708165B
Context. Some models for the topology of the magnetic field in
sunspot penumbrae predict regions free of magnetic fields or with
only dynamically weak fields in the deep photosphere. Aims:
We aim to confirm or refute the existence of weak-field regions in
the deepest photospheric layers of the penumbra. Methods:
We investigated the magnetic field at log τ5 = 0 is
by inverting spectropolarimetric data of two different sunspots
located very close to disk center with a spatial resolution of
approximately 0.4-0.45”. The data have been recorded using the GRIS
instrument attached to the 1.5-m solar telescope GREGOR at the El
Teide observatory. The data include three Fe I lines around 1565 nm,
whose sensitivity to the magnetic field peaks half a pressure scale
height deeper than the sensitivity of the widely used Fe I spectral
line pair at 630 nm. Before the inversion, the data were corrected
for the effects of scattered light using a deconvolution method with
several point spread functions. Results: At log τ5
= 0 we find no evidence of regions with dynamically weak (B&lt;
500 Gauss) magnetic fields in sunspot penumbrae. This result is much
more reliable than previous investigations made on Fe I lines at 630
nm. Moreover, the result is independent of the number of nodes employed
in the inversion, is independent of the point spread function used to
deconvolve the data, and does not depend on the amount of stray light
(I.e., wide-angle scattered light) considered.

---------------------------------------------------------
Title: Spectropolarimetric observations of an arch filament system
with the GREGOR solar telescope
Authors: Balthasar, H.; Gömöry, P.; González Manrique, S. J.;
Kuckein, C.; Kavka, J.; Kučera, A.; Schwartz, P.; Vašková, R.;
Berkefeld, T.; Collados Vera, M.; Denker, C.; Feller, A.; Hofmann,
A.; Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Pastor Yabar, A.;
Rezaei, R.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth,
M.; Sobotka, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier,
K. G.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
2016AN....337.1050B Altcode: 2016arXiv160901514B
Arch filament systems occur in active sunspot groups, where a fibril
structure connects areas of opposite magnetic polarity, in contrast to
active region filaments that follow the polarity inversion line. We
used the GREGOR Infrared Spectrograph (GRIS) to obtain the full
Stokes vector in the spectral lines Si I λ1082.7 nm, He I λ1083.0
nm, and Ca I λ1083.9 nm. We focus on the near-infrared calcium line
to investigate the photospheric magnetic field and velocities, and
use the line core intensities and velocities of the helium line to
study the chromospheric plasma. The individual fibrils of the arch
filament system connect the sunspot with patches of magnetic polarity
opposite to that of the spot. These patches do not necessarily coincide
with pores, where the magnetic field is strongest. Instead, areas are
preferred not far from the polarity inversion line. These areas exhibit
photospheric downflows of moderate velocity, but significantly higher
downflows of up to 30 km s-1 in the chromospheric helium
line. Our findings can be explained with new emerging flux where the
matter flows downward along the field lines of rising flux tubes,
in agreement with earlier results.

---------------------------------------------------------
Title: Magnetic fields of opposite polarity in sunspot penumbrae
Authors: Franz, M.; Collados, M.; Bethge, C.; Schlichenmaier, R.;
Borrero, J. M.; Schmidt, W.; Lagg, A.; Solanki, S. K.; Berkefeld,
T.; Kiess, C.; Rezaei, R.; Schmidt, D.; Sigwarth, M.; Soltau, D.;
Volkmer, R.; von der Luhe, O.; Waldmann, T.; Orozco, D.; Pastor Yabar,
A.; Denker, C.; Balthasar, H.; Staude, J.; Hofmann, A.; Strassmeier,
K.; Feller, A.; Nicklas, H.; Kneer, F.; Sobotka, M.
2016A&A...596A...4F Altcode: 2016arXiv160800513F
Context. A significant part of the penumbral magnetic field returns
below the surface in the very deep photosphere. For lines in the
visible, a large portion of this return field can only be detected
indirectly by studying its imprints on strongly asymmetric and
three-lobed Stokes V profiles. Infrared lines probe a narrow layer
in the very deep photosphere, providing the possibility of directly
measuring the orientation of magnetic fields close to the solar
surface. Aims: We study the topology of the penumbral magnetic
field in the lower photosphere, focusing on regions where it returns
below the surface. Methods: We analyzed 71 spectropolarimetric
datasets from Hinode and from the GREGOR infrared spectrograph. We
inferred the quality and polarimetric accuracy of the infrared data
after applying several reduction steps. Techniques of spectral
inversion and forward synthesis were used to test the detection
algorithm. We compared the morphology and the fractional penumbral
area covered by reversed-polarity and three-lobed Stokes V profiles for
sunspots at disk center. We determined the amount of reversed-polarity
and three-lobed Stokes V profiles in visible and infrared data of
sunspots at various heliocentric angles. From the results, we computed
center-to-limb variation curves, which were interpreted in the context
of existing penumbral models. Results: Observations in visible
and near-infrared spectral lines yield a significant difference in the
penumbral area covered by magnetic fields of opposite polarity. In
the infrared, the number of reversed-polarity Stokes V profiles is
smaller by a factor of two than in the visible. For three-lobed Stokes
V profiles the numbers differ by up to an order of magnitude.

---------------------------------------------------------
Title: Horizontal flow fields in and around a small active region. The
transition period between flux emergence and decay
Authors: Verma, M.; Denker, C.; Balthasar, H.; Kuckein, C.; González
Manrique, S. J.; Sobotka, M.; Bello González, N.; Hoch, S.; Diercke,
A.; Kummerow, P.; Berkefeld, T.; Collados, M.; Feller, A.; Hofmann,
A.; Kneer, F.; Lagg, A.; Löhner-Böttcher, J.; Nicklas, H.; Pastor
Yabar, A.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Schubert,
M.; Sigwarth, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier,
K. G.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
2016A&A...596A...3V Altcode: 2016arXiv160507462V
Context. The solar magnetic field is responsible for all aspects
of solar activity. Thus, emergence of magnetic flux at the surface
is the first manifestation of the ensuing solar activity. 
Aims: Combining high-resolution and synoptic observations aims to
provide a comprehensive description of flux emergence at photospheric
level and of the growth process that eventually leads to a mature
active region. Methods: The small active region NOAA 12118
emerged on 2014 July 17 and was observed one day later with the 1.5-m
GREGOR solar telescope on 2014 July 18. High-resolution time-series
of blue continuum and G-band images acquired in the blue imaging
channel (BIC) of the GREGOR Fabry-Pérot Interferometer (GFPI) were
complemented by synoptic line-of-sight magnetograms and continuum
images obtained with the Helioseismic and Magnetic Imager (HMI) onboard
the Solar Dynamics Observatory (SDO). Horizontal proper motions and
horizontal plasma velocities were computed with local correlation
tracking (LCT) and the differential affine velocity estimator (DAVE),
respectively. Morphological image processing was employed to measure
the photometric and magnetic area, magnetic flux, and the separation
profile of the emerging flux region during its evolution. 
Results: The computed growth rates for photometric area, magnetic
area, and magnetic flux are about twice as high as the respective
decay rates. The space-time diagram using HMI magnetograms of five days
provides a comprehensive view of growth and decay. It traces a leaf-like
structure, which is determined by the initial separation of the two
polarities, a rapid expansion phase, a time when the spread stalls,
and a period when the region slowly shrinks again. The separation
rate of 0.26 km s-1 is highest in the initial stage, and
it decreases when the separation comes to a halt. Horizontal plasma
velocities computed at four evolutionary stages indicate a changing
pattern of inflows. In LCT maps we find persistent flow patterns such
as outward motions in the outer part of the two major pores, a diverging
feature near the trailing pore marking the site of upwelling plasma and
flux emergence, and low velocities in the interior of dark pores. We
detected many elongated rapidly expanding granules between the two
major polarities, with dimensions twice as large as the normal granules.

---------------------------------------------------------
Title: Upper chromospheric magnetic field of a sunspot penumbra:
observations of fine structure
Authors: Joshi, J.; Lagg, A.; Solanki, S. K.; Feller, A.; Collados,
M.; Orozco Suárez, D.; Schlichenmaier, R.; Franz, M.; Balthasar,
H.; Denker, C.; Berkefeld, T.; Hofmann, A.; Kiess, C.; Nicklas, H.;
Pastor Yabar, A.; Rezaei, R.; Schmidt, D.; Schmidt, W.; Sobotka, M.;
Soltau, D.; Staude, J.; Strassmeier, K. G.; Volkmer, R.; von der Lühe,
O.; Waldmann, T.
2016A&A...596A...8J Altcode: 2016arXiv160801988J
 Aims: The fine-structure of the magnetic field in a sunspot
penumbra in the upper chromosphere is to be explored and compared
to that in the photosphere. Methods: Spectropolarimetric
observations with high spatial resolution were recorded with the 1.5-m
GREGOR telescope using the GREGOR Infrared Spectrograph (GRIS). The
observed spectral domain includes the upper chromospheric Hei triplet
at 10 830 Å and the photospheric Sii 10 827.1 Å and Cai 10 833.4 Å
spectral lines. The upper chromospheric magnetic field is obtained
by inverting the Hei triplet assuming a Milne-Eddington-type model
atmosphere. A height-dependent inversion was applied to the Sii 10
827.1 Å and Cai 10 833.4 Å lines to obtain the photospheric magnetic
field. Results: We find that the inclination of the magnetic
field varies in the azimuthal direction in the photosphere and in the
upper chromosphere. The chromospheric variations coincide remarkably
well with the variations in the inclination of the photospheric field
and resemble the well-known spine and interspine structure in the
photospheric layers of penumbrae. The typical peak-to-peak variations
in the inclination of the magnetic field in the upper chromosphere
are found to be 10°-15°, which is roughly half the variation in
the photosphere. In contrast, the magnetic field strength of the
observed penumbra does not vary on small spatial scales in the upper
chromosphere. Conclusions: Thanks to the high spatial resolution
of the observations that is possible with the GREGOR telescope at 1.08
microns, we find that the prominent small-scale fluctuations in the
magnetic field inclination, which are a salient part of the property
of sunspot penumbral photospheres, also persist in the chromosphere,
although at somewhat reduced amplitudes. Such a complex magnetic
configuration may facilitate penumbral chromospheric dynamic phenomena,
such as penumbral micro-jets or transient bright dots.

---------------------------------------------------------
Title: Active region fine structure observed at 0.08 arcsec resolution
Authors: Schlichenmaier, R.; von der Lühe, O.; Hoch, S.; Soltau, D.;
Berkefeld, T.; Schmidt, D.; Schmidt, W.; Denker, C.; Balthasar, H.;
Hofmann, A.; Strassmeier, K. G.; Staude, J.; Feller, A.; Lagg, A.;
Solanki, S. K.; Collados, M.; Sigwarth, M.; Volkmer, R.; Waldmann,
T.; Kneer, F.; Nicklas, H.; Sobotka, M.
2016A&A...596A...7S Altcode: 2016arXiv160707094S
Context. The various mechanisms of magneto-convective energy transport
determine the structure of sunspots and active regions. 
Aims: We characterise the appearance of light bridges and other
fine-structure details and elaborate on their magneto-convective
nature. Methods: We present speckle-reconstructed images taken
with the broad-band imager (BBI) at the 1.5 m GREGOR telescope in the
486 nm and 589 nm bands. We estimate the spatial resolution from the
noise characteristics of the image bursts and obtain 0.08″ at 589
nm. We describe structure details in individual best images as well
as the temporal evolution of selected features. Results: We
find branched dark lanes extending along thin (≈1″) light bridges
in sunspots at various heliocentric angles. In thick (≳ 2″) light
bridges the branches are disconnected from the central lane and have a Y
shape with a bright grain toward the umbra. The images reveal that light
bridges exist on varying intensity levels and that their small-scale
features evolve on timescales of minutes. Faint light bridges show
dark lanes outlined by the surrounding bright features. Dark lanes are
very common and are also found in the boundary of pores. They have a
characteristic width of 0.1″ or smaller. Intergranular dark lanes of
that width are seen in active region granulation. Conclusions: We
interpret our images in the context of magneto-convective simulations
and findings: while central dark lanes in thin light bridges are
elevated and associated with a density increase above upflows, the dark
lane branches correspond to locations of downflows and are depressed
relative to the adjacent bright plasma. Thick light bridges with central
dark lanes show no projection effect. They have a flat elevated plateau
that falls off steeply at the umbral boundary. There, Y-shaped filaments
form as they do in the inner penumbra. This indicates the presence of
inclined magnetic fields, meaning that the umbral magnetic field is
wrapped around the convective light bridge.

---------------------------------------------------------
Title: Probing deep photospheric layers of the quiet Sun with high
magnetic sensitivity
Authors: Lagg, A.; Solanki, S. K.; Doerr, H. -P.; Martínez González,
M. J.; Riethmüller, T.; Collados Vera, M.; Schlichenmaier, R.;
Orozco Suárez, D.; Franz, M.; Feller, A.; Kuckein, C.; Schmidt, W.;
Asensio Ramos, A.; Pastor Yabar, A.; von der Lühe, O.; Denker, C.;
Balthasar, H.; Volkmer, R.; Staude, J.; Hofmann, A.; Strassmeier,
K.; Kneer, F.; Waldmann, T.; Borrero, J. M.; Sobotka, M.; Verma, M.;
Louis, R. E.; Rezaei, R.; Soltau, D.; Berkefeld, T.; Sigwarth, M.;
Schmidt, D.; Kiess, C.; Nicklas, H.
2016A&A...596A...6L Altcode: 2016arXiv160506324L
Context. Investigations of the magnetism of the quiet Sun are hindered
by extremely weak polarization signals in Fraunhofer spectral
lines. Photon noise, straylight, and the systematically different
sensitivity of the Zeeman effect to longitudinal and transversal
magnetic fields result in controversial results in terms of the strength
and angular distribution of the magnetic field vector. Aims:
The information content of Stokes measurements close to the diffraction
limit of the 1.5 m GREGOR telescope is analyzed. We took the effects of
spatial straylight and photon noise into account. Methods: Highly
sensitive full Stokes measurements of a quiet-Sun region at disk center
in the deep photospheric Fe I lines in the 1.56 μm region were obtained
with the infrared spectropolarimeter GRIS at the GREGOR telescope. Noise
statistics and Stokes V asymmetries were analyzed and compared to a
similar data set of the Hinode spectropolarimeter (SOT/SP). Simple
diagnostics based directly on the shape and strength of the profiles
were applied to the GRIS data. We made use of the magnetic line ratio
technique, which was tested against realistic magneto-hydrodynamic
simulations (MURaM). Results: About 80% of the GRIS spectra
of a very quiet solar region show polarimetric signals above a 3σ
level. Area and amplitude asymmetries agree well with small-scale
surface dynamo-magneto hydrodynamic simulations. The magnetic line ratio
analysis reveals ubiquitous magnetic regions in the ten to hundred Gauss
range with some concentrations of kilo-Gauss fields. Conclusions:
The GRIS spectropolarimetric data at a spatial resolution of ≈0.̋4
are so far unique in the combination of high spatial resolution scans
and high magnetic field sensitivity. Nevertheless, the unavoidable
effect of spatial straylight and the resulting dilution of the weak
Stokes profiles means that inversion techniques still bear a high risk
of misinterpretating the data.

---------------------------------------------------------
Title: Flow and magnetic field properties in the trailing sunspots
of active region NOAA 12396
Authors: Verma, M.; Denker, C.; Böhm, F.; Balthasar, H.; Fischer,
C. E.; Kuckein, C.; Bello González, N.; Berkefeld, T.; Collados,
M.; Diercke, A.; Feller, A.; González Manrique, S. J.; Hofmann, A.;
Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Pator Yabar, A.; Rezaei,
R.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth, M.;
Sobotka, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier,
K. G.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
2016AN....337.1090V Altcode:
Improved measurements of the photospheric and chromospheric
three-dimensional magnetic and flow fields are crucial for a precise
determination of the origin and evolution of active regions. We present
an illustrative sample of multi-instrument data acquired during a
two-week coordinated observing campaign in August 2015 involving,
among others, the GREGOR solar telescope (imaging and near-infrared
spectroscopy) and the space missions Solar Dynamics Observatory (SDO)
and Interface Region Imaging Spectrograph (IRIS). The observations
focused on the trailing part of active region NOAA 12396 with complex
polarity inversion lines and strong intrusions of opposite polarity
flux. The GREGOR Infrared Spectrograph (GRIS) provided Stokes IQUV
spectral profiles in the photospheric Si I λ1082.7 nm line, the
chromospheric He I λ1083.0 nm triplet, and the photospheric Ca I
λ1083.9 nm line. Carefully calibrated GRIS scans of the active region
provided maps of Doppler velocity and magnetic field at different
atmospheric heights. We compare quick-look maps with those obtained
with the “Stokes Inversions based on Response functions” (SIR)
code, which furnishes deeper insight into the magnetic properties
of the region. We find supporting evidence that newly emerging flux
and intruding opposite polarity flux are hampering the formation
of penumbrae, i.e., a penumbra fully surrounding a sunspot is only
expected after cessation of flux emergence in proximity to the sunspots.

---------------------------------------------------------
Title: Three-dimensional structure of a sunspot light bridge
Authors: Felipe, T.; Collados, M.; Khomenko, E.; Kuckein, C.; Asensio
Ramos, A.; Balthasar, H.; Berkefeld, T.; Denker, C.; Feller, A.;
Franz, M.; Hofmann, A.; Joshi, J.; Kiess, C.; Lagg, A.; Nicklas, H.;
Orozco Suárez, D.; Pastor Yabar, A.; Rezaei, R.; Schlichenmaier,
R.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Sobotka, M.; Solanki,
S. K.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Volkmer, R.;
von der Lühe, O.; Waldmann, T.
2016A&A...596A..59F Altcode: 2016arXiv161104803F
Context. Active regions are the most prominent manifestations of solar
magnetic fields; their generation and dissipation are fundamental
problems in solar physics. Light bridges are commonly present during
sunspot decay, but a comprehensive picture of their role in the
removal of the photospheric magnetic field is still lacking. 
Aims: We study the three-dimensional configuration of a sunspot,
and in particular, its light bridge, during one of the last stages of
its decay. Methods: We present the magnetic and thermodynamical
stratification inferred from full Stokes inversions of the photospheric
Si I 10 827 Å and Ca I 10 839 Å lines obtained with the GREGOR
Infrared Spectrograph of the GREGOR telescope at the Observatorio del
Teide, Tenerife, Spain. The analysis is complemented by a study of
continuum images covering the disk passage of the active region, which
are provided by the Helioseismic and Magnetic Imager on board the Solar
Dynamics Observatory. Results: The sunspot shows a light bridge
with penumbral continuum intensity that separates the central umbra from
a smaller umbra. We find that in this region the magnetic field lines
form a canopy with lower magnetic field strength in the inner part. The
photospheric light bridge is dominated by gas pressure (high-β),
as opposed to the surrounding umbra, where the magnetic pressure
is higher. A convective flow is observed in the light bridge. This
flow is able to bend the magnetic field lines and to produce field
reversals. The field lines merge above the light bridge and become
as vertical and strong as in the surrounding umbra. We conclude that
this occurs because two highly magnetized regions approach each other
during the sunspot evolution. Movies associated to Figs. 2 and 13
are available at <A href="http://www.aanda.org">http://www.aanda.org</A>

---------------------------------------------------------
Title: Inference of magnetic fields in the very quiet Sun
Authors: Martínez González, M. J.; Pastor Yabar, A.; Lagg, A.;
Asensio Ramos, A.; Collados, M.; Solanki, S. K.; Balthasar, H.;
Berkefeld, T.; Denker, C.; Doerr, H. P.; Feller, A.; Franz, M.;
González Manrique, S. J.; Hofmann, A.; Kneer, F.; Kuckein, C.;
Louis, R.; von der Lühe, O.; Nicklas, H.; Orozco, D.; Rezaei, R.;
Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Sobotka,
M.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Verma, M.; Waldman,
T.; Volkmer, R.
2016A&A...596A...5M Altcode: 2018arXiv180410089M
Context. Over the past 20 yr, the quietest areas of the solar surface
have revealed a weak but extremely dynamic magnetism occurring
at small scales (&lt;500 km), which may provide an important
contribution to the dynamics and energetics of the outer layers of
the atmosphere. Understanding this magnetism requires the inference
of physical quantities from high-sensitivity spectro-polarimetric
data with high spatio-temporal resolution. Aims: We present
high-precision spectro-polarimetric data with high spatial resolution
(0.4”) of the very quiet Sun at 1.56 μm obtained with the GREGOR
telescope to shed some light on this complex magnetism. Methods:
We used inversion techniques in two main approaches. First, we assumed
that the observed profiles can be reproduced with a constant magnetic
field atmosphere embedded in a field-free medium. Second, we assumed
that the resolution element has a substructure with either two constant
magnetic atmospheres or a single magnetic atmosphere with gradients of
the physical quantities along the optical depth, both coexisting with
a global stray-light component. Results: Half of our observed
quiet-Sun region is better explained by magnetic substructure within
the resolution element. However, we cannot distinguish whether this
substructure comes from gradients of the physical parameters along the
line of sight or from horizontal gradients (across the surface). In
these pixels, a model with two magnetic components is preferred, and
we find two distinct magnetic field populations. The population with
the larger filling factor has very weak ( 150 G) horizontal fields
similar to those obtained in previous works. We demonstrate that the
field vector of this population is not constrained by the observations,
given the spatial resolution and polarimetric accuracy of our data. The
topology of the other component with the smaller filling factor is
constrained by the observations for field strengths above 250 G:
we infer hG fields with inclinations and azimuth values compatible
with an isotropic distribution. The filling factors are typically
below 30%. We also find that the flux of the two polarities is not
balanced. From the other half of the observed quiet-Sun area 50% are
two-lobed Stokes V profiles, meaning that 23% of the field of view
can be adequately explained with a single constant magnetic field
embedded in a non-magnetic atmosphere. The magnetic field vector and
filling factor are reliable inferred in only 50% based on the regular
profiles. Therefore, 12% of the field of view harbour hG fields with
filling factors typically below 30%. At our present spatial resolution,
70% of the pixels apparently are non-magnetised.

---------------------------------------------------------
Title: Fitting peculiar spectral profiles in He I 10830Å absorption
features
Authors: González Manrique, S. J.; Kuckein, C.; Pastor Yabar, A.;
Collados, M.; Denker, C.; Fischer, C. E.; Gömöry, P.; Diercke, A.;
Bello González, N.; Schlichenmaier, R.; Balthasar, H.; Berkefeld, T.;
Feller, A.; Hoch, S.; Hofmann, A.; Kneer, F.; Lagg, A.; Nicklas, H.;
Orozco Suárez, D.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Sobotka,
M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Verma,
M.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
2016AN....337.1057G Altcode: 2016arXiv160300679G
The new generation of solar instruments provides better
spectral, spatial, and temporal resolution for a better
understanding of the physical processes that take place on the
Sun. Multiple-component profiles are more commonly observed with these
instruments. Particularly, the He I 10830 Å triplet presents such
peculiar spectral profiles, which give information on the velocity
and magnetic fine structure of the upper chromosphere. The purpose
of this investigation is to describe a technique to efficiently fit
the two blended components of the He I 10830 Å triplet, which are
commonly observed when two atmospheric components are located within
the same resolution element. The observations used in this study were
taken on 2015 April 17 with the very fast spectroscopic mode of the
GREGOR Infrared Spectrograph (GRIS) attached to the 1.5-m GREGOR solar
telescope, located at the Observatorio del Teide, Tenerife, Spain. We
apply a double-Lorentzian fitting technique using Levenberg-Marquardt
least-squares minimization. This technique is very simple and much
faster than inversion codes. Line-of-sight Doppler velocities can
be inferred for a whole map of pixels within just a few minutes. Our
results show sub- and supersonic downflow velocities of up to 32 km
s-1 for the fast component in the vicinity of footpoints of
filamentary structures. The slow component presents velocities close
to rest.

---------------------------------------------------------
Title: The vertical thickness of Jupiter's Europa gas torus from
charged particle measurements
Authors: Kollmann, P.; Paranicas, C.; Clark, G.; Roussos, E.; Lagg,
A.; Krupp, N.
2016GeoRL..43.9425K Altcode:
Measurements and modeling suggest the presence of a neutral gas torus
collocated with the orbit of Jupiter's moon Europa. Here we use data
from the CMS instrument that is part of the Energetic Particles Detector
(EPD) on board the Galileo spacecraft to characterize the distribution
of 130 keV protons. Near the orbit of Europa this distribution has a
minimum around 70° in equatorial pitch angle. We reproduce this with
a model assuming that the protons are lost via charge exchange with
a gas torus. Since the pitch angle characterizes whether the protons
remain mostly in the dense center of the torus or continuously bounce
through it, we can determine the latitudinal extent of the torus. We
find that the full thickness where its density falls to 1/e of its
maximum has to be ≲2RJ and is closer to ≈1RJ.

---------------------------------------------------------
Title: Formation of a solar Hα filament from orphan penumbrae
Authors: Buehler, D.; Lagg, A.; van Noort, M.; Solanki, S. K.
2016A&A...589A..31B Altcode: 2016arXiv160305899B
 Aims: The formation and evolution of an Hα filament in active
region (AR) 10953 is described. Methods: Observations from the
Solar Optical Telescope (SOT) aboard the Hinode satellite starting
from UT 18:09 on 27th April 2007 until UT 06:08 on 1st May 2007 were
analysed. 20 scans of the 6302 Å Fe I line pair recorded by SOT/SP were
inverted using the spatially coupled version of the SPINOR code. The
inversions were analysed together with co-spatial SOT/BFI G-band and
Ca II H and SOT/NFI Hα observations. Results: Following the
disappearance of an initial Hα filament aligned along the polarity
inversion line (PIL) of the AR, a new Hα filament formed in its place
some 20 h later, which remained stable for, at least, another 1.5
days. The creation of the new Hα filament was driven by the ascent of
horizontal magnetic fields from the photosphere into the chromosphere
at three separate locations along the PIL. The magnetic fields at
two of these locations were situated directly underneath the initial
Hα filament and formed orphan penumbrae already aligned along the Hα
filament channel. The 700 G orphan penumbrae were stable and trapped in
the photosphere until the disappearance of the overlying initial Hα
filament, after which they started to ascend into the chromosphere at
10 ± 5 m/s. Each ascent was associated with a simultaneous magnetic
flux reduction of up to 50% in the photosphere. The ascended orphan
penumbrae formed dark seed structures in Hα in parallel with the PIL,
which elongated and merged to form an Hα filament. The filament channel
featured horizontal magnetic fields of on average 260 G at log (τ) =
-2 suspended above the nearly field-free lower photosphere. The fields
took on an overall inverse configuration at log (τ) = -2 suggesting
a flux rope topology for the new Hα filament. The destruction of the
initial Hα filament was likely caused by the flux emergence at the
third location along the PIL. Conclusions: We present a new
interpretation of the Hα filament formation in AR 10953 whereby the
mainly horizontal fields of orphan penumbrae, aligned along the Hα
filament channel, ascend into the chromosphere, forming seed fragments
for a new, second Hα filament. The orphan penumbral fields ascend
into the chromosphere ~9-24 h before the Hα filament is fully formed.

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Title: Flows in and around Active Region NOAA12118 Observed with
the GREGOR Solar Telescope and SDO/HMI
Authors: Verma, M.; Denker, C.; Balthasar, H.; Kuckein, C.; González
Manrique, S. J.; Sobotka, M.; Bello González, N.; Hoch, S.; Diercke,
A.; Kummerow, P.; Berkefeld, T.; Collados, M.; Feller, A.; Hofmann,
A.; Kneer, F.; Lagg, A.; Löhner-Böttcher, J.; Nicklas, H.; Pastor
Yabar, A.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Schubert,
M.; Sigwarth, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier,
K.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
2016ASPC..504...29V Altcode: 2016arXiv160301109V
Accurate measurements of magnetic and velocity fields in and around
solar active regions are key to unlocking the mysteries of the
formation and the decay of sunspots. High spatial resolution images
and spectral sequences with a high cadence obtained with the GREGOR
solar telescope give us an opportunity to scrutinize 3-D flow fields
with local correlation tracking and imaging spectroscopy. We present
GREGOR early science data acquired in 2014 July - August with the GREGOR
Fabry-Pérot Interferometer and the Blue Imaging Channel. Time-series
of blue continuum (λ 450.6 nm) images of the small active region
NOAA 12118 were restored with the speckle masking technique to derive
horizontal proper motions and to track the evolution of morphological
changes. In addition, high-resolution observations are discussed in
the context of synoptic data from the Solar Dynamics Observatory.

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Title: Depth-dependent global properties of a sunspot observed by
Hinode using the Solar Optical Telescope/Spectropolarimeter
Authors: Tiwari, Sanjiv K.; van Noort, Michiel; Solanki, Sami K.;
Lagg, Andreas
2015A&A...583A.119T Altcode: 2015arXiv150804830T
Context. For the past two decades, the three-dimensional structure
of sunspots has been studied extensively. A recent improvement in the
Stokes inversion technique prompts us to revisit the depth-dependent
properties of sunspots. Aims: In the present work, we aim to
investigate the global depth-dependent thermal, velocity, and magnetic
properties of a sunspot, as well as the interconnection between
various local properties. Methods: We analysed high-quality
Stokes profiles of the disk-centred, regular, leading sunspot of NOAA
AR 10933, acquired by the Solar Optical Telescope/Spectropolarimeter
(SOT/SP) on board the Hinode spacecraft. To obtain depth-dependent
stratification of the physical parameters, we used the recently
developed, spatially coupled version of the SPINOR inversion code. Results: First, we study the azimuthally averaged physical parameters
of the sunspot. We find that the vertical temperature gradient in the
lower- to mid-photosphere is at its weakest in the umbra, while it is
considerably stronger in the penumbra, and stronger still in the spot's
surroundings. The azimuthally averaged field becomes more horizontal
with radial distance from the centre of the spot, but more vertical
with height. At continuum optical depth unity, the line-of-sight
velocity shows an average upflow of ~300 ms-1 in the inner
penumbra and an average downflow of ~1300 ms-1 in the
outer penumbra. The downflow continues outside the visible penumbral
boundary. The sunspot shows, at most, a moderate negative twist of
&lt;5° at log (τ) = 0, which increases with height. The sunspot umbra
and the spines of the penumbra show considerable similarity with regard
to their physical properties, albeit with some quantitative differences
(weaker, somewhat more horizontal fields in spines, commensurate
with their location being further away from the sunspot's core). The
temperature shows a general anti-correlation with the field strength,
with the exception of the heads of penumbral filaments, where a weak
positive correlation is found. The dependence of the physical parameters
on each other over the full sunspot shows a qualitative similarity to
that of a standard penumbral filament and its surrounding spines. 
Conclusions: The large-scale variation in the physical parameters of
a sunspot at various optical depths is presented. Our results suggest
that the spines in the penumbra are basically the outward extension
of the umbra. The spines and the penumbral filaments, together, are
the basic elements that form a sunspot penumbra.

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Title: Statistical analysis of supersonic downflows in sunspot
penumbrae.
Authors: Kim, Hyunnam; Lagg, Andreas; Solanki, Sami K.; Narayan,
Gautam; van Noort, Michiel; Kim, Kap-Sung
2015IAUGA..2254868K Altcode:
Supersonic downflow patches was found in the outer edge of sunspot
penumbra. These patches are believed to be the return channels of the
Evershed flow. There was previous study to investigate their structure
in detail using Hinode SOT/SP observations (M. van Noort et al. 2013)
but their data sample was only two sunspots. To make general description
it needs to check more sunspot data sample.We selected 242 downflow
patches of 16 sunspots using Hinode SOT/SP observations from 2006 to
2012. Height-dependent maps of atmospheric parameters of these downflows
was produced by using HeLix which was height dependent LTE inversion
code of Stokes profiles.Statistical analysis of magnetic field strength,
inclination angle of field line, temperature and line-of-sight velocity
are presented. The recovered atmospheric data tell us that downflow
patches have different physical signatures comparing normal penumbra
properties. Furthermore, our results of three height-dependent layer
support that heating process should occur on the downflow patches in
the middle of layer.

---------------------------------------------------------
Title: Using Realistic MHD Simulations for Modeling and Interpretation
of Quiet-Sun Observations with the Solar Dynamics Observatory
Helioseismic and Magnetic Imager
Authors: Kitiashvili, I. N.; Couvidat, S.; Lagg, A.
2015ApJ...808...59K Altcode: 2014arXiv1407.2663K
The solar atmosphere is extremely dynamic, and many important phenomena
develop on small scales that are unresolved in observations with
the Helioseismic and Magnetic Imager (HMI) instrument on the Solar
Dynamics Observatory. For correct calibration and interpretation of
the observations, it is very important to investigate the effects
of small-scale structures and dynamics on the HMI observables,
such as Doppler shift, continuum intensity, spectral line depth,
and width. We use 3D radiative hydrodynamics simulations of the
upper turbulent convective layer and the atmosphere of the Sun, and
a spectro-polarimetric radiative transfer code to study observational
characteristics of the Fe i 6173 Å line observed by HMI in quiet-Sun
regions. We use the modeling results to investigate the sensitivity
of the line Doppler shift to plasma velocity, and also sensitivities
of the line parameters to plasma temperature and density, and
determine effective line formation heights for observations of solar
regions located at different distances from the disk center. These
estimates are important for the interpretation of helioseismology
measurements. In addition, we consider various center-to-limb effects,
such as convective blueshift, variations of helioseismic travel-times,
and the “concave” Sun effect, and show that the simulations can
qualitatively reproduce the observed phenomena, indicating that these
effects are related to a complex interaction of the solar dynamics
and radiative transfer.

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Title: Variation in sunspot properties between 1999 and 2014
Authors: Rezaei, R.; Beck, C.; Lagg, A.; Borrero, J. M.; Schmidt,
W.; Collados, M.
2015A&A...578A..43R Altcode:
 Aims: We study the variation in the magnetic field strength,
area, and continuum intensity of umbrae in solar cycles 23 and 24. Methods: We analyzed a sample of 374 sunspots observed from 1999
until 2014 with the Tenerife Infrared Polarimeter at the German
Vacuum Tower Telescope and the Facility InfRared Spectropolarimeter
at the Dunn Solar Telescope. The sample of field strength, area,
and intensities was used to trace any long-term or cyclic trend of
umbral properties in the last 15 years. Results: Sunspots
are systematically weaker, that is, have a weaker field strength and
stronger continuum intensity, toward the end of cycle 23 than they
had at the maximum of cycle 23. The linear trend reverses with the
onset of cycle 24. We find that the field strength decreases in the
declining phase of cycle 23 by about 112 (± 16) G yr-1,
while it increases in the rising phase of cycle 24 by about 138 (±
72) G yr-1. The umbral intensity shows the opposite trend:
the intensity increases with a rate of 0.7 (± 0.3)% of Ic
yr-1 toward the end of cycle 23 and decreases with a rate
of 3.8 (± 1.5)% of Ic yr-1 toward the maximum of
cycle 24. The distribution of the umbral maximum field strength in cycle
24 is similar to that of cycle 23, but is slightly shifted toward lower
values by about 80 G, corresponding to a possible long-term gradient in
umbral field strength of about 7 ± 4 G yr-1. If instead of
the maximum umbral field we consider the average value over the entire
umbra, the distribution shifts by about 44 Gauss. Conclusions:
The umbral brightness decreases in the rising stage of a solar cycle,
but increases from maximum toward the end of the cycle. Our results
do not indicate a drastic change of the solar cycle toward a grand
minimum in the near future.

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Title: Properties of solar plage from a spatially coupled inversion
of Hinode SP data
Authors: Buehler, D.; Lagg, A.; Solanki, S. K.; van Noort, M.
2015A&A...576A..27B Altcode: 2015arXiv150101151B
 Aims: The properties of magnetic fields forming an extended
plage region in AR 10953 were investigated. Methods:
Stokes spectra of the Fe I line pair at 6302 Å recorded by the
spectropolarimeter aboard the Hinode satellite were inverted using
the SPINOR code. The code performed a 2D spatially coupled inversion
on the Stokes spectra, allowing the retrieval of gradients in optical
depth within the atmosphere of each pixel, whilst accounting for the
effects of the instrument's PSF. Consequently, no magnetic filling
factor was needed. Results: The inversion results reveal that
plage is composed of magnetic flux concentrations (MFCs) with typical
field strengths of 1520 G at log (τ) = -0.9 and inclinations of
10°-15°. The MFCs expand by forming magnetic canopies composed of
weaker and more inclined magnetic fields. The expansion and average
temperature stratification of isolated MFCs can be approximated well
with an empirical plage thin flux tube model. The highest temperatures
of MFCs are located at their edges in all log (τ) layers. Whilst
the plasma inside MFCs is nearly at rest, each is surrounded by a
ring of downflows of on average 2.4 km s-1 at log (τ)
= 0 and peak velocities of up to 10 km s-1, which are
supersonic. The downflow ring of an MFC weakens and shifts outwards
with height, tracing the MFC's expansion. Such downflow rings often
harbour magnetic patches of opposite polarity to that of the main MFC
with typical field strengths below 300 G at log (τ) = 0. These opposite
polarity patches are situated beneath the canopy of their main MFC. We
found evidence of a strong broadening of the Stokes profiles in MFCs
and particularly in the downflow rings surrounding MFCs (expressed
by a microturbulence in the inversion). This indicates the presence
of strong unresolved velocities. Larger magnetic structures such as
sunspots cause the field of nearby MFCs to be more inclined.

---------------------------------------------------------
Title: Comparison of inversion codes for polarized line formation
in MHD simulations. I. Milne-Eddington codes
Authors: Borrero, J. M.; Lites, B. W.; Lagg, A.; Rezaei, R.; Rempel, M.
2014A&A...572A..54B Altcode: 2014arXiv1409.3376B
Milne-Eddington (M-E) inversion codes for the radiative transfer
equation are the most widely used tools to infer the magnetic field
from observations of the polarization signals in photospheric and
chromospheric spectral lines. Unfortunately, a comprehensive comparison
between the different M-E codes available to the solar physics
community is still missing, and so is a physical interpretation of their
inferences. In this contribution we offer a comparison between three
of those codes (VFISV, ASP/HAO, and HeLIx+). These codes are
used to invert synthetic Stokes profiles that were previously obtained
from realistic non-grey three-dimensional magnetohydrodynamical (3D MHD)
simulations. The results of the inversion are compared with each other
and with those from the MHD simulations. In the first case, the M-E
codes retrieve values for the magnetic field strength, inclination and
line-of-sight velocity that agree with each other within σB
≤ 35 (Gauss), σγ ≤ 1.2°, and σv ≤
10 m s-1, respectively. Additionally, M-E inversion codes
agree with the numerical simulations, when compared at a fixed optical
depth, within σB ≤ 130 (Gauss), σγ ≤ 5°,
and σv ≤ 320 m s-1. Finally, we show that
employing generalized response functions to determine the height at
which M-E codes measure physical parameters is more meaningful than
comparing at a fixed geometrical height or optical depth. In this case
the differences between M-E inferences and the 3D MHD simulations
decrease to σB ≤ 90 (Gauss), σγ ≤ 3°,
and σv ≤ 90 m s-1.

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Title: Inclinations of small quiet-Sun magnetic features based on
a new geometric approach
Authors: Jafarzadeh, S.; Solanki, S. K.; Lagg, A.; Bellot Rubio,
L. R.; van Noort, M.; Feller, A.; Danilovic, S.
2014A&A...569A.105J Altcode: 2014arXiv1408.2443J
Context. High levels of horizontal magnetic flux have been reported
in the quiet-Sun internetwork, often based on Stokes profile
inversions. Aims: Here we introduce a new method for deducing
the inclination of magnetic elements and use it to test magnetic field
inclinations from inversions. Methods: We determine accurate
positions of a set of small, bright magnetic elements in high spatial
resolution images sampling different photospheric heights obtained by
the Sunrise balloon-borne solar observatory. Together with estimates
of the formation heights of the employed spectral bands, these provide
us with the inclinations of the magnetic features. We also compute
the magnetic inclination angle of the same magnetic features from the
inversion of simultaneously recorded Stokes parameters. Results:
Our new, geometric method returns nearly vertical fields (average
inclination of around 14° with a relatively narrow distribution
having a standard deviation of 6°). In strong contrast to this, the
traditionally used inversions give almost horizontal fields (average
inclination of 75 ± 8°) for the same small magnetic features,
whose linearly polarised Stokes profiles are adversely affected by
noise. We show that for such magnetic features inversions overestimate
the flux in horizontal magnetic fields by an order of magnitude. 
Conclusions: The almost vertical field of bright magnetic features from
our geometric method is clearly incompatible with the nearly horizontal
magnetic fields obtained from the inversions. This indicates that the
amount of magnetic flux in horizontal fields deduced from inversions is
overestimated in the presence of weak Stokes signals, in particular if
Stokes Q and U are close to or under the noise level. Inversions should
be used with great caution when applied to data with no clear Stokes Q
and no U signal. By combining the proposed method with inversions we are
not just improving the inclination, but also the field strength. This
technique allows us to analyse features that are not reliably treated
by inversions, thus greatly extending our capability to study the
complete magnetic field of the quiet Sun.

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Title: Vigorous convection in a sunspot granular light bridge
Authors: Lagg, Andreas; Solanki, Sami K.; van Noort, Michiel;
Danilovic, Sanja
2014A&A...568A..60L Altcode: 2014arXiv1407.1202L
Context. Light bridges are the most prominent manifestation of
convection in sunspots. The brightest representatives are granular
light bridges composed of features that appear to be similar to
granules. Aims: An in-depth study of the convective motions,
temperature stratification, and magnetic field vector in and around
light bridge granules is presented with the aim of identifying
similarities and differences to typical quiet-Sun granules. 
Methods: Spectropolarimetric data from the Hinode Solar Optical
Telescope were analyzed using a spatially coupled inversion technique
to retrieve the stratified atmospheric parameters of light bridge and
quiet-Sun granules. Results: Central hot upflows surrounded by
cooler fast downflows reaching 10 km s-1 clearly establish
the convective nature of the light bridge granules. The inner part
of these granules in the near surface layers is field free and is
covered by a cusp-like magnetic field configuration. We observe
hints of field reversals at the location of the fast downflows. The
quiet-Sun granules in the vicinity of the sunspot are covered by a
low-lying canopy field extending radially outward from the spot. Conclusions: The similarities between quiet-Sun and light bridge
granules point to the deep anchoring of granular light bridges in
the underlying convection zone. The fast, supersonic downflows are
most likely a result of a combination of invigorated convection
in the light bridge granule due to radiative cooling into the
neighboring umbra and the fact that we sample deeper layers, since the
downflows are immediately adjacent to the slanted walls of the Wilson
depression. The two movies are available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201424071/olm">http://www.aanda.org</A>

---------------------------------------------------------
Title: Migration of Ca II H bright points in the internetwork
Authors: Jafarzadeh, S.; Cameron, R. H.; Solanki, S. K.; Pietarila,
A.; Feller, A.; Lagg, A.; Gandorfer, A.
2014A&A...563A.101J Altcode: 2014arXiv1401.7522J
Context. The migration of magnetic bright point-like features (MBP)
in the lower solar atmosphere reflects the dispersal of magnetic
flux as well as the horizontal flows of the atmospheric layer they
are embedded in. Aims: We analyse trajectories of the proper
motion of intrinsically magnetic, isolated internetwork Ca ii H MBPs
(mean lifetime 461 ± 9 s) to obtain their diffusivity behaviour. Methods: We use seeing-free high spatial and temporal resolution
image sequences of quiet-Sun, disc-centre observations obtained in
the Ca ii H 3968 Å passband of the Sunrise Filter Imager (SuFI)
onboard the Sunrise balloon-borne solar observatory. Small MBPs in
the internetwork are automatically tracked. The trajectory of each
MBP is then calculated and described by a diffusion index (γ) and
a diffusion coefficient (D). We also explore the distribution of the
diffusion indices with the help of a Monte Carlo simulation. 
Results: We find γ = 1.69 ± 0.08 and D = 257 ± 32 km2
s-1 averaged over all MBPs. Trajectories of most MBPs are
classified as super-diffusive, i.e. γ &gt; 1, with the determined γ
being the largest obtained so far to our knowledge. A direct correlation
between D and timescale (τ) determined from trajectories of all MBPs is
also obtained. We discuss a simple scenario to explain the diffusivity
of the observed, relatively short-lived MBPs while they migrate within
a small area in a supergranule (i.e. an internetwork area). We show
that the scatter in the γ values obtained for individual MBPs is due
to their limited lifetimes. Conclusions: The super-diffusive
MBPs can be described as random walkers (due to granular evolution and
intergranular turbulence) superposed on a large systematic (background)
velocity, caused by granular, mesogranular, and supergranular flows.

---------------------------------------------------------
Title: Magnetic structure of an activated filament in a flaring
active region
Authors: Sasso, C.; Lagg, A.; Solanki, S. K.
2014A&A...561A..98S Altcode: 2013arXiv1312.2781S
 Aims: While the magnetic field in quiescent prominences has
been widely investigated, less is known about the field in activated
prominences. We report observational results on the magnetic field
structure of an activated filament in a flaring active region. In
particular, we studied its magnetic structure and line-of-sight flows
during its early activated phase, shortly before it displayed signs
of rotation. Methods: We inverted the Stokes profiles of the
chromospheric He i 10 830 Å triplet and the photospheric Si i 10 827
Å line observed in this filament by the Vacuum Tower Telescope on
Tenerife. Using these inversion results, we present and interpret the
first maps of the velocity and magnetic field obtained in an activated
filament, both in the photosphere and the chromosphere. Results:
Up to five different magnetic components are found in the chromospheric
layers of the filament, while outside the filament a single component is
sufficient to reproduce the observations. Magnetic components displaying
an upflow are preferentially located towards the centre of the filament,
while the downflows are concentrated along its periphery. Moreover,
the upflowing gas is associated with an opposite-polarity magnetic
configuration with respect to the photosphere, while the downflowing gas
is associated with a same-polarity configuration. Conclusions:
The activated filament has a very complex structure. Nonetheless,
it is compatible with a flux rope, albeit a distorted one, in
the normal configuration. The observations are best explained
by a rising flux rope in which part of the filament material is
still stably stored (upflowing material, rising with the field),
while the rest is no longer stably stored and flows down along the
field lines. The movie is available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201322481/olm">http://www.aanda.org</A>

---------------------------------------------------------
Title: Analysis of magnetic fields in a plage region using a spatially
coupled 2D inversion technique
Authors: Buehler, David; Lagg, Andreas; Solanki, Sami K.; Van Noort,
Michiel
2014cosp...40E.427B Altcode:
The properties of magnetic features (MFCs) within a plage region
in the vicinity of a sunspot were investigated at high spatial
resolution. Stokes spectra of the 630nm line pair recorded by the
spectropolarimeter aboard Hinode were inverted using an extended
version of the SPINOR code. The code preformed a spatially coupled
inversion of the Stokes spectra using three log(tau) nodes in optical
depth. No magnetic filling factors was employed. The analysis of the
inversion results reveals that the MFCs have typical field strengths
of 1500G at log(tau)=-0.9 and inclinations between 10-15 degrees in
all three log(tau) nodes. The MFCs expand by forming magnetic canopies
composed of weaker and more inclined magnetic fields. The expansion of
the magnetic field and temperature stratification of MFCs with optical
depth is in good agreement with a thin flux tube model. Whilst the gas
inside magnetic flux concentrations is typically at rest, the majority
of MFCs were surrounded by a ring of downflows with an average value
of 2.5km/s at log(tau)=0. The ring gradually shifts outwards following
the expansion of the MFC. Within the downflow rings of MFCs small
magnetic patches of opposite polarity to that of the main MFC were
identified, which are predominantly situated beneath the canopy of
its main MFC. We found evidence for a strong broadening of the Stokes
profiles within MFCs and their surrounding downflow rings (expressed
by a microturbulence in the inversion). This indicates the presence
of strong unresolved velocities.

---------------------------------------------------------
Title: Peripheral downflows in sunspot penumbrae
Authors: van Noort, M.; Lagg, A.; Tiwari, S. K.; Solanki, S. K.
2013A&A...557A..24V Altcode: 2013arXiv1308.0466V
Context. Sunspot penumbrae show high-velocity patches along
the periphery. Aims: The high-velocity downflow patches
are believed to be the return channels of the Evershed flow. We
aim to investigate their structure in detail using Hinode SOT/SP
observations. Methods: We employ Fourier interpolation in
combination with spatially coupled height dependent LTE inversions
of Stokes profiles to produce high-resolution, height-dependent maps
of atmospheric parameters of these downflows and investigate their
properties. Results: High-speed downflows are observed over
a wide range of viewing angles. They have supersonic line-of-sight
velocities, some in excess of 20 km s-1, and very high
magnetic field strengths, reaching values of over 7 kG. A relation
between the downflow velocities and the magnetic field strength is
found, in good agreement with MHD simulations. Conclusions:
The coupled inversion at high resolution allows for the accurate
determination of small-scale structures. The recovered atmospheric
structure indicates that regions with very high downflow velocities
contain some of the strongest magnetic fields that have ever been
measured on the Sun. Two movies are available in electronic form
at <A href="http://www.aanda.org">http://www.aanda.org</A>

---------------------------------------------------------
Title: Structure of sunspot penumbral filaments: a remarkable
uniformity of properties
Authors: Tiwari, Sanjiv Kumar; van Noort, Michiel; Lagg, Andreas;
Solanki, Sami K.
2013A&A...557A..25T Altcode: 2013arXiv1307.3668T
Context. The sunspot penumbra comprises numerous thin, radially
elongated filaments that are central for heat transport within
the penumbra, but whose structure is still not clear. Aims:
We aim to investigate the fine-scale structure of these penumbral
filaments. Methods: We perform a depth-dependent inversion of
spectropolarimetric data of a sunspot very close to solar disk center
obtained by Solar Optical Telescope/Spectropolarimeter onboard the
Hinode spacecraft. We have used a recently developed, spatially coupled
2D inversion scheme, which allows us to analyze the fine structure
of individual penumbral filaments up to the diffraction limit of
the telescope. Results: Filaments of different sizes in all
parts of the penumbra display very similar magnetic field strengths,
inclinations, and velocity patterns. The temperature structure is also
similar, although the filaments in the inner penumbra have cooler
tails than those in the outer penumbra. The similarities allowed
us to average all these filaments and to subsequently extract the
physical properties common to all of them. This average filament
shows upflows associated with an upward-pointing field at its inner,
umbral end (head) and along its axis, as well as downflows along the
lateral edge and strong downflows in the outer end (tail) associated
with a nearly vertical, strong, and downward-pointing field. The
upflowing plasma is significantly, i.e., up to 800 K, hotter than the
downflowing plasma. The hot, tear-shaped head of the averaged filament
can be associated with a penumbral grain. The central part of the
filament shows nearly horizontal fields with strengths in the range
of 1 kG. The field above the filament converges, whereas a diverging
trend is seen in the deepest layers near the head of the filament. The
fluctuations in the physical parameters along and across the filament
increase rapidly with depth. Conclusions: We put forward a
unified observational picture of a sunspot penumbral filament. It
is consistent with such a filament being a magneto-convective cell,
in line with recent magnetohydrodynamic simulations. The uniformity
of its properties over the penumbra sets constraints on penumbral
models and simulations. The complex and inhomogeneous structure of the
filament provides a natural explanation for a number of long-running
controversies in the literature.

---------------------------------------------------------
Title: Quiet Sun magnetic fields observed by Hinode: Support for a
local dynamo
Authors: Buehler, D.; Lagg, A.; Solanki, S. K.
2013A&A...555A..33B Altcode: 2013arXiv1307.0789B
Context. The Hinode mission has revealed copious amounts of horizontal
flux covering the quiet Sun. Local dynamo action has been proposed
to explain the presence of this flux. Aims: We sought to
test whether the quiet Sun flux detected by Hinode is due to a
local or the global dynamo by studying long-term variations in the
polarisation signals detectable at the disc centre of the quiet Sun
between November 2006 and May 2012, with particular emphasis on weak
signals in the internetwork. Methods: The investigation focusses
on line-integrated circular polarisation Vtot and linear
polarisation LPtot profiles obtained from the Fe I 6302.5
Å absorption line in Hinode SOT/SP. Results: Both circular and
linear polarisation signals show no overall variation in the fraction
of selected pixels from 2006 until 2012. There is also no variation
in the magnetic flux in this interval of time. The probability density
functions (PDF) of the line-of-sight magnetic flux can be fitted with
a power law from 1.17 × 1017 Mx to 8.53 × 1018
Mx with index α = -1.82 ± 0.02 in 2007. The variation of α's across
all years does not exceed a significance of 1σ. Linearly polarised
features are also fitted with a power law, with index α = -2.60 ±
0.06 in 2007. Indices derived from linear polarisation PDFs of other
years also show no significant variation. Conclusions: Our
results show that the ubiquitous horizontal polarisation on the edges
of bright granules seen by Hinode are invariant during the minimum of
cycle 23. This supports the notion that the weak circular and linear
polarisation is primarily caused by an independent local dynamo.

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Title: Chromospheric magnetic field of an active region filament
using the He I triplet and the primary observation of filaments
(prominences) using New Vacuum Solar Tower of China
Authors: Xu, Zhi; Lagg, A.; Solanki, S.; Liu, Z.; New Vacuum Solar
Telescope Observers
2013SPD....4410504X Altcode:
There are two parts in my presentation. In the first part I present the
magnetic field measurement of an active region filament using the full
Stokes profiles of He I 10830 and Si I 10827 band when the filament in
its stable phase. This observation was fulfilled using German Vacuum
Tower Telescope (VTT). The vector magnetic field and Doppler velocity
map both in the photosphere and chromosphere were observed and analyzed
co-temporally and co-spatially. The observation findings reveal that we
were observing the emergence of a flux rope with a subsequent formation
of a filament. In the second part, I would like to exhibit another
ground-based observation facility, 1m New Vacuum Solar Telescope
(NVST) located in Fu-Xian Lake Solar Observatory of China. After
the basic introduction including the location and instrumentations,
I give some high lights including granulation, faculae, micro-flares,
jets, and filaments or prominence since the first running in 2010,
showing our potential ability to do high-resolution solar observation
from the ground. Observation proposals from the international solar
community are well appreciated in future.

---------------------------------------------------------
Title: Structure and dynamics of isolated internetwork Ca II H bright
points observed by SUNRISE
Authors: Jafarzadeh, S.; Solanki, S. K.; Feller, A.; Lagg, A.;
Pietarila, A.; Danilovic, S.; Riethmüller, T. L.; Martínez Pillet, V.
2013A&A...549A.116J Altcode: 2012arXiv1211.4836J
 Aims: We aim to improve our picture of the low chromosphere in
the quiet-Sun internetwork by investigating the intensity, horizontal
velocity, size and lifetime variations of small bright points (BPs;
diameter smaller than 0.3 arcsec) observed in the Ca II H 3968 Å
passband along with their magnetic field parameters, derived from
photospheric magnetograms. Methods: Several high-quality
time series of disc-centre, quiet-Sun observations from the Sunrise
balloon-borne solar telescope, with spatial resolution of around 100
km on the solar surface, have been analysed to study the dynamics
of BPs observed in the Ca II H passband and their dependence on the
photospheric vector magnetogram signal. Results: Parameters such
as horizontal velocity, diameter, intensity and lifetime histograms of
the isolated internetwork and magnetic Ca II H BPs were determined. Mean
values were found to be 2.2 km s-1, 0.2 arcsec (≈150 km),
1.48 ⟨ ICa ⟩ and 673 s, respectively. Interestingly, the
brightness and the horizontal velocity of BPs are anti-correlated. Large
excursions (pulses) in horizontal velocity, up to 15 km s-1,
are present in the trajectories of most BPs. These could excite kink
waves travelling into the chromosphere and possibly the corona, which we
estimate to carry an energy flux of 310 W m-2, sufficient to
heat the upper layers, although only marginally. Conclusions:
The stable observing conditions of Sunrise and our technique for
identifying and tracking BPs have allowed us to determine reliable
parameters of these features in the internetwork. Thus we find, e.g.,
that they are considerably longer lived than previously thought. The
large velocities are also reliable, and may excite kink waves. Although
these wave are (marginally) energetic enough to heat the quiet corona,
we expect a large additional contribution from larger magnetic elements
populating the network and partly also the internetwork.

---------------------------------------------------------
Title: The GREGOR Solar Telescope on Tenerife
Authors: Schmidt, W.; von der Lühe, O.; Volkmer, R.; Denker, C.;
Solanki, S. K.; Balthasar, H.; Bello González, N.; Berkefeld, T.;
Collados Vera, M.; Hofmann, A.; Kneer, F.; Lagg, A.; Puschmann, K. G.;
Schmidt, D.; Sobotka, M.; Soltau, D.; Strassmeier, K. G.
2012ASPC..463..365S Altcode: 2012arXiv1202.4289S
2011 was a successful year for the GREGOR project. The telescope was
finally completed in May with the installation of the 1.5-meter primary
mirror. The installation of the first-light focal plane instruments was
completed by the end of the year. At the same time, the preparations
for the installation of the high-order adaptive optics were finished,
its integration to the telescope is scheduled for early 2012. This
paper describes the telescope and its instrumentation in their present
first-light configuration, and provides a brief overview of the science
goals of GREGOR.

---------------------------------------------------------
Title: The GREGOR Solar Telescope
Authors: Denker, C.; Lagg, A.; Puschmann, K. G.; Schmidt, D.; Schmidt,
W.; Sobotka, M.; Soltau, D.; Strassmeier, K. G.; Volkmer, R.; von
der Luehe, O.; Solanki, S. K.; Balthasar, H.; Bello Gonzalez, N.;
Berkefeld, T.; Collados Vera, M.; Hofmann, A.; Kneer, F.
2012IAUSS...6E.203D Altcode:
The 1.5-meter GREGOR solar telescope is a new facility for
high-resolution observations of the Sun. The telescope is located at the
Spanish Observatorio del Teide on Tenerife. The telescope incorporates
advanced designs for a foldable-tent dome, an open steel-truss telescope
structure, and active and passive means to minimize telescope and mirror
seeing. Solar fine structure can be observed with a dedicated suite
of instruments: a broad-band imaging system, the "GREGOR Fabry-Perot
Interferometer", and the "Grating Infrared Spectrograph". All post-focus
instruments benefit from a high-order (multi-conjugate) adaptive optics
system, which enables observations close to the diffraction limit of
the telescope. The inclusion of a spectrograph for stellar activity
studies and the search for solar twins expands the scientific usage
of the GREGOR to the nighttime domain. We report on the successful
commissioning of the telescope until the end of 2011 and the first
steps towards science verification in 2012.

---------------------------------------------------------
Title: A retrospective of the GREGOR solar telescope in scientific
literature
Authors: Denker, C.; von der Lühe, O.; Feller, A.; Arlt, K.;
Balthasar, H.; Bauer, S. -M.; Bello González, N.; Berkefeld, Th.;
Caligari, P.; Collados, M.; Fischer, A.; Granzer, T.; Hahn, T.;
Halbgewachs, C.; Heidecke, F.; Hofmann, A.; Kentischer, T.; Klva{ňa,
M.; Kneer, F.; Lagg, A.; Nicklas, H.; Popow, E.; Puschmann, K. G.;
Rendtel, J.; Schmidt, D.; Schmidt, W.; Sobotka, M.; Solanki, S. K.;
Soltau, D.; Staude, J.; Strassmeier, K. G.; Volkmer, R.; Waldmann,
T.; Wiehr, E.; Wittmann, A. D.; Woche, M.
2012AN....333..810D Altcode: 2012arXiv1210.3167D
In this review, we look back upon the literature, which had the
GREGOR solar telescope project as its subject including science cases,
telescope subsystems, and post-focus instruments. The articles date
back to the year 2000, when the initial concepts for a new solar
telescope on Tenerife were first presented at scientific meetings. This
comprehensive bibliography contains literature until the year 2012,
i.e., the final stages of commissioning and science verification. Taking
stock of the various publications in peer-reviewed journals and
conference proceedings also provides the “historical” context
for the reference articles in this special issue of Astronomische
Nachrichten/Astronomical Notes.

---------------------------------------------------------
Title: The 1.5 meter solar telescope GREGOR
Authors: Schmidt, W.; von der Lühe, O.; Volkmer, R.; Denker, C.;
Solanki, S. K.; Balthasar, H.; Bello Gonzalez, N.; Berkefeld, Th.;
Collados, M.; Fischer, A.; Halbgewachs, C.; Heidecke, F.; Hofmann,
A.; Kneer, F.; Lagg, A.; Nicklas, H.; Popow, E.; Puschmann, K. G.;
Schmidt, D.; Sigwarth, M.; Sobotka, M.; Soltau, D.; Staude, J.;
Strassmeier, K. G.; Waldmann , T. A.
2012AN....333..796S Altcode:
The 1.5 m telescope GREGOR opens a new window to the understanding
of solar small-scale magnetism. The first light instrumentation
includes the Gregor Fabry Pérot Interferometer (GFPI), a filter
spectro-polarimeter for the visible wavelength range, the GRating
Infrared Spectro-polarimeter (GRIS) and the Broad-Band Imager (BBI). The
excellent performance of the first two instruments has already been
demonstrated at the Vacuum Tower Telescope. GREGOR is Europe's largest
solar telescope and number 3 in the world. Its all-reflective Gregory
design provides a large wavelength coverage from the near UV up to at
least 5 microns. The field of view has a diameter of 150 arcsec. GREGOR
is equipped with a high-order adaptive optics system, with a subaperture
size of 10 cm, and a deformable mirror with 256 actuators. The science
goals are focused on, but not limited to, solar magnetism. GREGOR
allows us to measure the emergence and disappearance of magnetic flux
at the solar surface at spatial scales well below 100 km. Thanks to its
spectro-polarimetric capabilities, GREGOR will measure the interaction
between the plasma flows, different kinds of waves, and the magnetic
field. This will foster our understanding of the processes that heat the
chromosphere and the outer layers of the solar atmosphere. Observations
of the surface magnetic field at very small spatial scales will shed
light on the variability of the solar brightness.

---------------------------------------------------------
Title: GRIS: The GREGOR Infrared Spectrograph
Authors: Collados, M.; López, R.; Páez, E.; Hernández, E.; Reyes,
M.; Calcines, A.; Ballesteros, E.; Díaz, J. J.; Denker, C.; Lagg,
A.; Schlichenmaier, R.; Schmidt, W.; Solanki, S. K.; Strassmeier,
K. G.; von der Lühe, O.; Volkmer, R.
2012AN....333..872C Altcode:
This paper describes the main characteristics of GRIS (GREGOR Infrared
Spectrograph), the grating spectrograph installed in the recently
inaugurated (May 2012) 1.5-meter GREGOR telescope located at the
Observatorio del Teide in Tenerife. The spectrograph has a standard
Czerny-Turner configuration with parabolic collimator and camera mirrors
that belong to the same conic surface. Although nothing prevents its
use at visible wavelengths, the spectrograph will be initially used
in combination with the infrared detector of the Tenerife Infrared
Polarimeter (TIP-II) in standard spectroscopic mode as well as for
spectropolarimetric measurements.

---------------------------------------------------------
Title: Chromospheric magnetic fields of an active region filament
Authors: Xu, Z.; Solanki, S.; Lagg, A.
2012EAS....55..163X Altcode:
Vector magnetic fields of an active region filament are co-spatially
and co-temporally mapped in photosphere and upper chromosphere, by
using spectro-polarimetric observations made by Tenerife Infrared
Polarimeter (TIP II) at the German Vacuum Tower Telescope (VTT). A
Zeeman-based ME inversion is performed on the full Stokes vectors
of both the photospheric Si I 1082.7 nm and the chromospheric He
I 1083.0 nm lines. We found that the strong magnetic fields, with
the field strength of 600 - 800 G in the He I line formation height,
are not uncommon among AR filaments. But such strong magnetic field
is not always found in AR filaments.

---------------------------------------------------------
Title: First Results from the SUNRISE Mission
Authors: Solanki, S. K.; Barthol, P.; Danilovic, S.; Feller, A.;
Gandorfer, A.; Hirzberger, J.; Jafarzadeh, S.; Lagg, A.; Riethmüller,
T. L.; Schüssler, M.; Wiegelmann, T.; Bonet, J. A.; González,
M. J. M.; Pillet, V. M.; Khomenko, E.; Yelles Chaouche, L.; Iniesta,
J. C. d. T.; Domingo, V.; Palacios, J.; Knölker, M.; González,
N. B.; Borrero, J. M.; Berkefeld, T.; Franz, M.; Roth, M.; Schmidt,
W.; Steiner, O.; Title, A. M.
2012ASPC..455..143S Altcode:
The SUNRISE balloon-borne solar observatory consists of a 1m aperture
Gregory telescope, a UV filter imager, an imaging vector polarimeter,
an image stabilization system, and further infrastructure. The first
science flight of SUNRISE yielded high-quality data that reveal the
structure, dynamics, and evolution of solar convection, oscillations,
and magnetic fields at a resolution of around 100 km in the quiet
Sun. Here we describe very briefly the mission and the first results
obtained from the SUNRISE data, which include a number of discoveries.

---------------------------------------------------------
Title: Solar magnetism eXplorer (SolmeX). Exploring the magnetic
field in the upper atmosphere of our closest star
Authors: Peter, Hardi; Abbo, L.; Andretta, V.; Auchère, F.; Bemporad,
A.; Berrilli, F.; Bommier, V.; Braukhane, A.; Casini, R.; Curdt,
W.; Davila, J.; Dittus, H.; Fineschi, S.; Fludra, A.; Gandorfer, A.;
Griffin, D.; Inhester, B.; Lagg, A.; Landi Degl'Innocenti, E.; Maiwald,
V.; Sainz, R. Manso; Martínez Pillet, V; Matthews, S.; Moses, D.;
Parenti, S.; Pietarila, A.; Quantius, D.; Raouafi, N. -E.; Raymond, J.;
Rochus, P.; Romberg, O.; Schlotterer, M.; Schühle, U.; Solanki, S.;
Spadaro, D.; Teriaca, L.; Tomczyk, S.; Trujillo Bueno, J.; Vial, J. -C.
2012ExA....33..271P Altcode: 2011arXiv1108.5304P; 2011ExA...tmp..134P
The magnetic field plays a pivotal role in many fields of
Astrophysics. This is especially true for the physics of the solar
atmosphere. Measuring the magnetic field in the upper solar atmosphere
is crucial to understand the nature of the underlying physical
processes that drive the violent dynamics of the solar corona—that
can also affect life on Earth. SolmeX, a fully equipped solar space
observatory for remote-sensing observations, will provide the first
comprehensive measurements of the strength and direction of the
magnetic field in the upper solar atmosphere. The mission consists
of two spacecraft, one carrying the instruments, and another one in
formation flight at a distance of about 200 m carrying the occulter to
provide an artificial total solar eclipse. This will ensure high-quality
coronagraphic observations above the solar limb. SolmeX integrates two
spectro-polarimetric coronagraphs for off-limb observations, one in
the EUV and one in the IR, and three instruments for observations on
the disk. The latter comprises one imaging polarimeter in the EUV for
coronal studies, a spectro-polarimeter in the EUV to investigate the low
corona, and an imaging spectro-polarimeter in the UV for chromospheric
studies. SOHO and other existing missions have investigated the emission
of the upper atmosphere in detail (not considering polarization),
and as this will be the case also for missions planned for the near
future. Therefore it is timely that SolmeX provides the final piece of
the observational quest by measuring the magnetic field in the upper
atmosphere through polarimetric observations.

---------------------------------------------------------
Title: Magnetic Fields of an Active Region Filament from Full Stokes
Analysis of Si I 1082.7 nm and He I 1083.0 nm
Authors: Xu, Z.; Lagg, A.; Solanki, S.; Liu, Y.
2012ApJ...749..138X Altcode: 2012arXiv1202.4562X
Vector magnetic fields of an active region filament in the photosphere
and upper chromosphere are obtained from spectro-polarimetric
observations recorded with the Tenerife Infrared Polarimeter (TIP II) at
the German Vacuum Tower Telescope. We apply Milne-Eddington inversions
on full Stokes vectors of the photospheric Si I 1082.7 nm and the upper
chromospheric He I triplet at 1083.0 nm to obtain the magnetic field
vector and velocity maps in two atmosphere layers. We find that (1) a
complete filament was already present in Hα at the beginning of the TIP
II data acquisition. Only a partially formed one, composed of multiple
small threads, was present in He I. (2) The AR filament comprises two
sections. One shows strong magnetic field intensities, about 600-800
G in the upper chromosphere and 800-1000 G in the photosphere. The
other exhibits only comparatively weak magnetic field strengths in both
layers. (3) The Stokes V signal is indicative of a dip in the magnetic
field strength close to the chromospheric PIL. (4) In the chromosphere,
consistent upflows are found along the PIL flanked by downflows. (5)
The transversal magnetic field is nearly parallel to the PIL in the
photosphere and inclined by 20°-30° in the chromosphere. (6) The
chromospheric magnetic field around the filament is found to be in
normal configuration, while the photospheric field presents a concave
magnetic topology. The observations are consistent with the emergence
of a flux rope with a subsequent formation of a filament.

---------------------------------------------------------
Title: Solar Particle Acceleration Radiation and Kinetics (SPARK). A
mission to understand the nature of particle acceleration
Authors: Matthews, Sarah A.; Williams, David R.; Klein, Karl-Ludwig;
Kontar, Eduard P.; Smith, David M.; Lagg, Andreas; Krucker, Sam;
Hurford, Gordon J.; Vilmer, Nicole; MacKinnon, Alexander L.; Zharkova,
Valentina V.; Fletcher, Lyndsay; Hannah, Iain G.; Browning, Philippa
K.; Innes, Davina E.; Trottet, Gerard; Foullon, Clare; Nakariakov,
Valery M.; Green, Lucie M.; Lamoureux, Herve; Forsyth, Colin; Walton,
David M.; Mathioudakis, Mihalis; Gandorfer, Achim; Martinez-Pillet,
Valentin; Limousin, Olivier; Verwichte, Erwin; Dalla, Silvia; Mann,
Gottfried; Aurass, Henri; Neukirch, Thomas
2012ExA....33..237M Altcode: 2011ExA...tmp..124M
Energetic particles are critical components of plasma populations
found throughout the universe. In many cases particles are accelerated
to relativistic energies and represent a substantial fraction of
the total energy of the system, thus requiring extremely efficient
acceleration processes. The production of accelerated particles
also appears coupled to magnetic field evolution in astrophysical
plasmas through the turbulent magnetic fields produced by diffusive
shock acceleration. Particle acceleration is thus a key component
in helping to understand the origin and evolution of magnetic
structures in, e.g. galaxies. The proximity of the Sun and the range
of high-resolution diagnostics available within the solar atmosphere
offers unique opportunities to study the processes involved in particle
acceleration through the use of a combination of remote sensing
observations of the radiative signatures of accelerated particles, and
of their plasma and magnetic environment. The SPARK concept targets the
broad range of energy, spatial and temporal scales over which particle
acceleration occurs in the solar atmosphere, in order to determine how
and where energetic particles are accelerated. SPARK combines highly
complementary imaging and spectroscopic observations of radiation from
energetic electrons, protons and ions set in their plasma and magnetic
context. The payload comprises focusing-optics X-ray imaging covering
the range from 1 to 60 keV; indirect HXR imaging and spectroscopy
from 5 to 200 keV, γ-ray spectroscopic imaging with high-resolution
LaBr3 scintillators, and photometry and source localisation
at far-infrared wavelengths. The plasma environment of the regions
of acceleration and interaction will be probed using soft X-ray
imaging of the corona and vector magnetography of the photosphere
and chromosphere. SPARK is designed for solar research. However,
in addition it will be able to provide exciting new insights into the
origin of particle acceleration in other regimes, including terrestrial
gamma-ray flashes (TGF), the origin of γ-ray bursts, and the possible
existence of axions.

---------------------------------------------------------
Title: Diffusivity of Isolated Internetwork Ca II H Bright Points
Observed by SuFI/SUNRISE
Authors: Jafarzadeh, S.; Solanki, S. K.; Cameron, R. H.; Feller, A.;
Pietarila, A.; Lagg, A.; Barthol, P.; Berkefeld, T.; Gandorfer, A.;
Knoelker, M.; Martinez Pillet, V.; Schmidt, W.; Title, A.
2012decs.confE..99J Altcode:
We analyze trajectories of the proper motion of intrinsically magnetic,
isolated internetwork Ca II H BPs (with mean lifetime of 461 sec) to
obtain their diffusivity behaviors. We use high spatial and temporal
resolution image sequences of quiet-Sun, disc-centre observations
obtained in the Ca II H 397 nm passband of the Sunrise Filter Imager
(SuFI) on board the SUNRISE balloon-borne solar observatory. In
order to avoid misidentification, the BPs are semi-manually selected
and then automatically tracked. The trajectory of each BP is then
calculated and its diffusion index is described by a power law
exponent, using which we classify the BPs' trajectories into sub-,
normal and super- diffusive. In addition, the corresponding diffusion
coefficients (D) based on the observed displacements are consequently
computed. We find a strong super-diffusivity at a height sampled by the
SuFI/SUNRISE Ca II H passband (i.e. a height corresponding roughly to
the temperature minimum). We find that 74% of the identified tiny BPs
are super-diffusive, 18% move randomly (i.e. their motion corresponds
to normal diffusion) and only 8% belong to the sub-diffusion regime. In
addition, we find that 53% of the super-diffusion regime (i.e. 39% of
all BPs) have the diffusivity index of 2 which are termed as "Ballistic
BPs". Finally, we explore the distribution of diffusion index with the
help of a simple simulation. The results suggest that the BPs are random
walkers superposed by a systematic (background) velocity in which the
magnitude of each component (and hence their ratio) depends on the time
and spatial scales. We further discuss a simple sketch to explain the
diffusivity of observed BPs while they migrate within a supergranule
(i.e. internetwork areas) or close to the network regions.

---------------------------------------------------------
Title: Siphon flow in a cool magnetic loop
Authors: Bethge, C.; Beck, C.; Peter, H.; Lagg, A.
2012A&A...537A.130B Altcode: 2011arXiv1111.5564B
Context. Siphon flows that are driven by a gas pressure difference
between two photospheric footpoints of different magnetic field strength
connected by magnetic field lines are a well-studied phenomenon in
theory, but observational evidence is scarce. Aims. We investigate the
properties of a structure in the solar chromosphere in an active region
to find out whether the feature is consistent with a siphon flow in
a magnetic loop filled with chromospheric material. Methods. We
derived the line-of-sight (LOS) velocity of several photospheric
spectral lines and two chromospheric spectral lines, Ca II H 3968.5
*Aring; and He I 10830 Å, in spectropolarimetric observations of
NOAA 10978 done with the Tenerife Infrared Polarimeter (TIP-II) and
the POlarimetric LIttrow Spectrograph (POLIS). The structure can be
clearly traced in the LOS velocity maps and the absorption depth of
He I. The magnetic field configuration in the photosphere is inferred
directly from the observed Stokes parameters and from inversions with
the HELIX+ code. Data from the full-disk Chromospheric
Telescope (ChroTel) in He I in intensity and LOS velocity are used for
tracking the temporal evolution of the flow, along with TRACE Fe IX/X
171 Å data for additional information about coronal regions related to
the structure under investigation. Results. The inner end of the
structure is located in the penumbra of a sunspot. It shows downflows
whose strength decreases with decreasing height in the atmosphere. The
flow velocity in He I falls abruptly from above 40 km s-1
to about zero further into the penumbra. A slight increase of emission
is seen in the Ca II H spectra at the endpoint. At the outer end of the
structure, the photospheric lines that form higher up in the atmosphere
show upflows that accelerate with height. The polarization signal near
the outer end shows a polarity opposite to that of the sunspot, the
magnetic field strength of 580 G is roughly half as large as at the
inner end. The structure exists for about 90 min. Its appearance is
preceeded by a brightening in its middle in the coronal TRACE data. Conclusions. The observed flows match theoretical predictions of
chromospheric and coronal siphon flows, with accelerating upflowing
plasma at one footpoint with low field strength and decelerating
downflowing plasma at the other end. A tube shock at the inner end is
probable, but the evidence is not conclusive. The TRACE data suggest
that the structure forms because of a reorganization of field lines
after a reconnection event.

---------------------------------------------------------
Title: Variation of quiet Sun magnetic elements between 2006 and
2011 using Hinode SOT/SP
Authors: Buehler, D.; Lagg, A.; Solanki, S. K.
2011sdmi.confE..76B Altcode:
The Hinode satellite has revealed copious amounts of horizontal flux
covering the quiet Sun, nurturing the notion of local dynamo action
operating close to the solar surface. We sought to investigate the
variation in the occurrence as well as the strength of circular and
linear polarisation on the quiet Sun during the minimum of cycle
23, covering a period from November 2006 until August 2011. This
investigation used Hinode SOT/SP images of the disk centre and a large
FOV and focussed on line-integrated linear and circular polarisation
signals obtained from the Fe I 6302.5 Å absorption line. The circular
polarisation showed an overall linear decline in occurrence from
November 2006 until August 2011. By comparing PDFs we found that
this decline is associated in particular with network elements. The
internetwork on the other hand showed a 10% decrease in occurrence
from November 2010 until June 2009, followed by an equal increase
until August 2011. The investigation also revealed a reduction of 30%
in the occurrence of linear polarisation signals between November 2006
and December 2009. From August 2010 until August 2011 the occurrence of
linear polarisation was increasing again. Hence, our results show that
the occurrence of the ubiquitous linear polarisation of the internetwork
as seen by Hinode is measurably influenced by the solar cycle. This
implies that an independent local dynamo process is unlikely to be
the sole cause responsible for the generation of this magnetic flux.

---------------------------------------------------------
Title: The Sun at high resolution: first results from the Sunrise
mission
Authors: Solanki, S. K.; Barthol, P.; Danilovic, S.; Feller,
A.; Gandorfer, A.; Hirzberger, J.; Lagg, A.; Riethmüller, T. L.;
Schüssler, M.; Wiegelmann, T.; Bonet, J. A.; Pillet, V. Martínez;
Khomenko, E.; del Toro Iniesta, J. C.; Domingo, V.; Palacios, J.;
Knölker, M.; González, N. Bello; Borrero, J. M.; Berkefeld, T.;
Franz, M.; Roth, M.; Schmidt, W.; Steiner, O.; Title, A. M.
2011IAUS..273..226S Altcode:
The Sunrise balloon-borne solar observatory consists of a 1m aperture
Gregory telescope, a UV filter imager, an imaging vector polarimeter,
an image stabilization system and further infrastructure. The first
science flight of Sunrise yielded high-quality data that reveal the
structure, dynamics and evolution of solar convection, oscillations
and magnetic fields at a resolution of around 100 km in the quiet
Sun. Here we describe very briefly the mission and the first results
obtained from the Sunrise data, which include a number of discoveries.

---------------------------------------------------------
Title: The height of chromospheric loops in an emerging flux region
Authors: Merenda, L.; Lagg, A.; Solanki, S. K.
2011A&A...532A..63M Altcode: 2012arXiv1202.1113M
Context. The chromospheric layer observable with the He i 10 830 Å
triplet is strongly warped. The analysis of the magnetic morphology of
this layer therefore requires a reliable technique to determine the
height at which the He i absorption takes place. Aims: The He
i absorption signature connecting two pores of opposite polarity in an
emerging flux region is investigated. This signature is suggestive of a
loop system connecting the two pores. We aim to show that limits can be
set on the height of this chromospheric loop system. Methods: The
increasing anisotropy in the illumination of a thin, magnetic structure
intensifies the linear polarization signal observed in the He i triplet
with height. This signal is altered by the Hanle effect. We apply an
inversion technique incorporating the joint action of the Hanle and
Zeeman effects, with the absorption layer height being one of the
free parameters. Results: The observed linear polarization
signal can be explained only if the loop apex is higher than ≈ 5
Mm. Best agreement with the observations is achieved for a height of
6.3 Mm. Conclusions: The strength of the linear polarization
signal in the loop apex is inconsistent with the assumption of a He
i absorption layer at a constant height level. The determined height
supports the earlier conclusion that dark He 10 830 Å filaments in
emerging flux regions trace emerging loops.

---------------------------------------------------------
Title: Polarimetry with GREGOR
Authors: Balthasar, H.; Bello González, N.; Collados, M.; Denker,
C.; Feller, A.; Hofmann, A.; Lagg, A.; Nagaruju, L.; Puschmann, K. G.;
Soltau, D.; Volkmer, R.
2011ASPC..437..351B Altcode:
A brief description of the new 1.5-meter solar telescope GREGOR located
at the Observatorio del Teide in Tenerife will be given. GREGOR will
provide a spatial resolution of about 75 km on the Sun, and with its
light collecting capability we will be able to study the development
of small magnetic features with high cadence. From the beginning,
it will be equipped with the GREGOR Fabry-Pérot Interferometer
(GFPI) for the visible spectral range and with a GRating Infrared
Spectrograph (GRIS). Both postfocus instruments can be combined
with a polarimeter, and in both cases the light is modulated by two
ferro-electric liquid crystals. A calibration unit can be inserted to
determine the instrumental polarization. Because of the altazimuthal
mount, time-dependent rotation of the polarimetric reference plane
is introduced, and we have to develop a polarization model of the
telescope. Measurements to verify this model are in preparation.

---------------------------------------------------------
Title: Intensity contrast from MHD simulations and HINODE observations
Authors: Afram, N.; Unruh, Y. C.; Solanki, S. K.; Schüssler, M.;
Lagg, A.; Vögler, A.
2011A&A...526A.120A Altcode: 2010arXiv1011.6102A
Context. Changes in the solar surface area, which is covered by
small-scale magnetic elements, are thought to cause long-term changes
in the solar spectral irradiance, which are important for determining
the impact on Earth's climate. Aims: To study the effect of
small-scale magnetic elements on the total and spectral irradiance,
we derive their contrasts from 3-D MHD simulations of the solar
atmosphere. These calculations are necessary because measurements of
small-scale flux tube contrasts are confined to a few wavelengths and
affected by scattered light and instrument defocus, even for space
observations. Methods: To test the contrast calculations,
we compare rms contrasts from simulations with those obtained with
the broad-band filter imager mounted on the Solar Optical Telescope
(SOT) onboard the Hinode satellite and also analyse centre-to-limb
variations (CLV). The 3-D MHD simulations include the interaction
between convection and magnetic flux tubes. They are performed by
assuming non-grey radiative transfer and using the MURaM code. The
simulations have an average vertical magnetic field of 0 G, 50 G, and
200 G. Emergent intensities are calculated with the spectral synthesis
code ATLAS9 and are convolved with a theoretical point-spread function
to account for the properties of the observations' optical system. Results: We find reasonable agreement between simulated and observed
intensity distributions in the visible continuum bands. Agreement is
poorer for the CN and G-bands. The analysis of the simulations uncovers
a potentially more realistic centre-to-limb behaviour than calculations
based on 1-D model atmospheres. Conclusions: We conclude that
starting from 3-D MHD simulations represents a powerful approach
to obtaining intensity contrasts for a wide wavelength coverage and
different positions across on the solar disk. This also paves the way
for future calculations of facular and network contrast as a function
of magnetic fluxes.

---------------------------------------------------------
Title: Multicomponent He I 10 830 Å profiles in an active filament
Authors: Sasso, C.; Lagg, A.; Solanki, S. K.
2011A&A...526A..42S Altcode: 2011arXiv1101.5563S
 Aims: We present new spectropolarimetric observations of the
chromospheric He i 10 830 Å multiplet observed in a filament during
its phase of activity. Methods: The data were recorded with the
new Tenerife Infrared Polarimeter (TIP-II) at the German Vacuum Tower
Telescope (VTT) on 2005 May 18. We inverted the He Stokes profiles
using multiple atmospheric components. Results: The observed
He Stokes profiles display a remarkably wide variety of shapes. Most
of the profiles show very broad Stokes I absorptions and complex and
spatially variable Stokes V signatures. The inversion of the profiles
shows evidence of different atmospheric blue- and redshifted components
of the He i lines within the resolution element (~1 arcsec), with
supersonic velocities of up to ~100 km s-1. Up to five
different atmospheric components are found in the same profile. We
show that even these complex profiles can be reliably inverted.

---------------------------------------------------------
Title: Fully Resolved Quiet-Sun Magnetic flux Tube Observed with
the SUNRISE/IMAX Instrument
Authors: Lagg, A.; Solanki, S. K.; Riethmüller, T. L.; Martínez
Pillet, V.; Schüssler, M.; Hirzberger, J.; Feller, A.; Borrero,
J. M.; Schmidt, W.; del Toro Iniesta, J. C.; Bonet, J. A.; Barthol, P.;
Berkefeld, T.; Domingo, V.; Gandorfer, A.; Knölker, M.; Title, A. M.
2010ApJ...723L.164L Altcode: 2010arXiv1009.0996L
Until today, the small size of magnetic elements in quiet-Sun areas has
required the application of indirect methods, such as the line-ratio
technique or multi-component inversions, to infer their physical
properties. A consistent match to the observed Stokes profiles could
only be obtained by introducing a magnetic filling factor that specifies
the fraction of the observed pixel filled with magnetic field. Here,
we investigate the properties of a small magnetic patch in the quiet
Sun observed with the IMaX magnetograph on board the balloon-borne
telescope SUNRISE with unprecedented spatial resolution and low
instrumental stray light. We apply an inversion technique based on
the numerical solution of the radiative transfer equation to retrieve
the temperature stratification and the field strength in the magnetic
patch. The observations can be well reproduced with a one-component,
fully magnetized atmosphere with a field strength exceeding 1 kG and
a significantly enhanced temperature in the mid to upper photosphere
with respect to its surroundings, consistent with semi-empirical flux
tube models for plage regions. We therefore conclude that, within the
framework of a simple atmospheric model, the IMaX measurements resolve
the observed quiet-Sun flux tube.

---------------------------------------------------------
Title: Magnetic structures of an emerging flux region in the solar
photosphere and chromosphere
Authors: Xu, Z.; Lagg, A.; Solanki, S. K.
2010A&A...520A..77X Altcode:
 Aims: We investigate the vector magnetic field and Doppler
velocity in the photosphere and upper chromosphere of a young
emerging flux region of the sun close to disk center. Methods:
Spectropolarimetric scans of a young active region made using the
second generation Tenerife Infrared Polarimeter (TIP II) on the German
Vacuum Tower Telescope (VTT) are analyzed. The scanned area contained
multiple sunspots and an emerging flux region. An inversion based on
the Milne-Eddington approximation was performed on the full Stokes
vector of the chromospheric He I 10 830 Å and the photospheric Si I
10 827.1 Å lines. This provided the magnetic vector and line-of-sight
velocity at each spatial point in both atmospheric layers. 
Results: A clear difference is seen between the complex magnetic
structure of the emerging flux region (EFR) in the photosphere and
the much simpler structure in the upper chromosphere. The upper
chromospheric structure is consistent with a set of emerging loops
following elongated dark structures seen in the He I 10 830 Å triplet,
similar to arch filament systems (AFS), while in the photosphere we
infer the presence of U-loops within the emergence zone. Nonetheless, in
general the upper chromospheric field has a similar linear relationship
between inclination angle and field strength as the photospheric field:
the field is weak (≈300 G) and horizontal in the emergence zone,
but strong (up to 850 G) and more vertical near its edges. The field
strength decreases from the photosphere to the upper chromosphere
by approximately 0.1-0.2 G km-1 (or even less) within the
emergence zone and by 0.3-0.6 G km-1 in sunspots located
at its edge. We reconstructed the magnetic field in 3D based on the
chromospheric vector field under the assumption that the He I 10 830 Å
triplet forms along the magnetic field loops. The reconstructed loops
are quite flat with supersonic downflows at both footpoints. Arguments
and evidence for an enhanced formation height of He I 10 830 Å in
arch-filaments seen in this line are provided, which support the
validity of the reconstructed loops. Conclusions: The main
chromospheric properties of EFRs previously deduced for a single region
NOAA 9451 are shown to be valid for another region as well, suggesting
that the main original results may have a wider application. The main
exception is that only the first region displayed a current sheet in
the chromosphere. We propose a scenario in which the relatively complex
photospheric structure evolves into the simpler chromospheric one.

---------------------------------------------------------
Title: GREGOR telescope: start of commissioning
Authors: Volkmer, R.; von der Lühe, O.; Denker, C.; Solanki, S.;
Balthasar, H.; Berkefeld, T.; Caligari, P.; Collados, M.; Halbgewachs,
C.; Heidecke, F.; Hofmann, A.; Klvana, M.; Kneer, F.; Lagg, A.; Popow,
E.; Schmidt, D.; Schmidt, W.; Sobotka, M.; Soltau, D.; Strassmeier, K.
2010SPIE.7733E..0KV Altcode: 2010SPIE.7733E..18V
With the integration of a 1-meter Cesic primary mirror the GREGOR
telescope pre-commissioning started. This is the first time, that
the entire light path has seen sunlight. The pre-commissioning period
includes testing of the main optics, adaptive optics, cooling system,
and pointing system. This time was also used to install a near-infrared
grating spectro-polarimeter and a 2D-spectropolarimeter for the visible
range as first-light science instruments. As soon as the final 1.5
meter primary mirror is installed, commissioning will be completed,
and an extended phase of science verification will follow. In the near
future, GREGOR will be equipped with a multi-conjugate adaptive optics
system that is presently under development at KIS.

---------------------------------------------------------
Title: GREGOR solar telescope: Design and status
Authors: Volkmer, R.; von der Lühe, O.; Denker, C.; Solanki, S. K.;
Balthasar, H.; Berkefeld, T.; Caligari, P.; Collados, M.; Fischer, A.;
Halbgewachs, C.; Heidecke, F.; Hofmann, A.; Klvaňa, M.; Kneer, F.;
Lagg, A.; Popow, E.; Schmidt, D.; Schmidt, W.; Sobotka, M.; Soltau,
D.; Strassmeier, K. G.
2010AN....331..624V Altcode:
The integration and verification phase of the GREGOR telescope
reached an important milestone with the installation of the
interim 1 m SolarLite primary mirror. This was the first time
that the entire light path had seen sunlight. Since then extensive
testing of the telescope and its subsystems has been carried out. The
integration and verification phase will culminate with the delivery and
installation of the final 1.5 m Zerodur primary mirror in the summer of
2010. Observatory level tests and science verification will commence in
the second half of 2010 and in 2011. This phase includes testing of the
main optics, adaptive optics, cooling and pointing systems. In addition,
assuming the viewpoint of a typical user, various observational modes
of the GREGOR Fabry-Pérot Interferometer (GFPI), the Grating Infrared
Spectrograph (GRIS), and high-speed camera systems will be tested to
evaluate if they match the expectations and science requirements. This
ensures that GREGOR will provide high-quality observations with its
combination of (multi-conjugate) adaptive optics and advanced post-focus
instruments. Routine observations are expected for 2012.

---------------------------------------------------------
Title: The calibration of the Cassini-Huygens CAPS Electron
Spectrometer
Authors: Lewis, G. R.; Arridge, C. S.; Linder, D. R.; Gilbert, L. K.;
Kataria, D. O.; Coates, A. J.; Persoon, A.; Collinson, G. A.; André,
N.; Schippers, P.; Wahlund, J.; Morooka, M.; Jones, G. H.; Rymer,
A. M.; Young, D. T.; Mitchell, D. G.; Lagg, A.; Livi, S. A.
2010P&SS...58..427L Altcode:
We present the two-stage method used to calibrate the electron
spectrometer (ELS), part of the plasma spectrometer (CAPS) on board
the Cassini spacecraft currently in orbit around Saturn. The CAPS-ELS
is a top-hat electrostatic analyser designed to measure electron
fluxes between 0.5 eV and 26 keV. The on-ground calibration method
described here includes the production of photoelectrons, which are
energised and passed into the CAPS-ELS in a purpose designed calibration
facility. Knowledge of the intensity of these incident electrons and
the subsequent instrument output provides an on-ground calibrated
geometric factor. Comparative studies of physical quantities such as
plasma density and electron differential flux calculated using on-ground
calibration factor with the quantities deduced from the wave experiment
and high energy electron detector provide in-flight calibration. The
results of this are presented together with a comparison of the
experimentally calibrated values with simulated calibration values.

---------------------------------------------------------
Title: Nonlinear force-free modelling: influence of inaccuracies in
the measured magnetic vector
Authors: Wiegelmann, T.; Yelles Chaouche, L.; Solanki, S. K.; Lagg, A.
2010A&A...511A...4W Altcode: 2009arXiv0912.3002W
Context. Solar magnetic fields are regularly extrapolated into the
corona starting from photospheric magnetic measurements that can
be affected by significant uncertainty. Aims: We study how
inaccuracies introduced into the maps of the photospheric magnetic
vector by the inversion of ideal and noisy Stokes parameters influence
the extrapolation of nonlinear force-free magnetic fields. 
Methods: We compute nonlinear force-free magnetic fields based on
simulated vector magnetograms, by the inversion of Stokes profiles
that were computed by a 3-D radiation MHD simulation snapshot. These
extrapolations are compared with extrapolations that originate directly
in the field in the MHD simulations, which is our reference. We
investigate how line formation and instrumental effects such as noise,
limited spatial resolution, and the effect of employing a filter
instrument influence the resulting magnetic field structure. The
comparison is performed qualitatively by visually inspecting the
magnetic field distribution and quantitatively by different metrics. Results: The reconstructed field is most accurate if ideal Stokes
data are inverted and becomes less accurate if instrumental effects
and noise are included. The results demonstrate that the nonlinear
force-free field extrapolation method tested here is relatively
insensitive to the effects of noise in measured polarization spectra
at levels consistent with present-day instruments. Conclusions:
Our results show that we can reconstruct the coronal magnetic field as
a nonlinear force-free field from realistic photospheric measurements
with an accuracy of a few percent, at least in the absence of sunspots.

---------------------------------------------------------
Title: Temperatures of small scale magnetic structures in deep solar
photospheric layers
Authors: Oklay, Nilda; Gandorfer, Achim; Lagg, Andreas; Solanki,
Sami K.; Bianda, Michele; Ramelli, Renzo
2010cosp...38.2857O Altcode: 2010cosp.meet.2857O
With current solar instrumentation, small scale magnetic
structures still remain unresolved. Nevertheless, it is possible
to retrieve information about these unresolved magnetic structures
via spectropolarimetry. For this reason, IRSOL (Istituto Ricerche
Solari Locarno) facility is used to obtain simultaneously recorded
spectra of Stokes I and Stokes V/I of CI (5380.3 A), FeI (5379.6 A,
5383.4 A) and TiII (5381.0 A) lines on an active region using the
ZIMPOL II (Zurich Imaging Polarimeter II) instrument. We used Stokes V
amplitude ratios technique to investigate temperatures of unresolved
magnetic features down to deep photospheric layers. Atmospheric
parameters are obtained from the inversions done with the SPINOR code
(Stokes-Profile-INversion-O-Routines). Then the results are compared
with the results from the realistic MHD simulations obtained from
MURaM code (MPS/University of Chicago radiative MHD). Comparisons of
the results from observations, inversions and numerical simulations
show a good agreement, which confirms the usage of this technique as
a temperature diagnostic tool.

---------------------------------------------------------
Title: How do inaccuracies and unresolved structures in the measured
solar photospheric magnetic vector influence the accuracy of coronal
magnetic field models?
Authors: Wiegelmann, Thomas; Yelles, Lotfi; Solanki, Sami; Lagg,
Andreas
2010cosp...38.2827W Altcode: 2010cosp.meet.2827W
Solar magnetic fields are usually extrapolated into the corona
starting from photospheric mag-netic measurements that can suffer from
significant uncertainties caused by the presence of unresolved fine
structures due to a limited spatial resolution and by the limited
polarimet-ric accuracy and spectral resolution. We investigate
how these inaccuracies in the measured photospheric magnetic field
vector influence the accuracy of the extrapolated coronal mag-netic
field. We compare non-linear force-free coronal magnetic field
extrapolations from a 3-D radiation MHD simulation snapshot with
corresponding extrapolations from synthetic vector magnetograms. The
synthetic magnetograms contain instrumental effects such as noise,
limited spatial and spectral resolution and the effect of employing a
filter instrument. The parameters are chosen in particular to mimic the
effects of the Hinode/SOT and the future Solar Orbiter PHI instruments,
respectively. We discuss, how photospheric structures, which are
inherent in the MHD snapshot, but not resolved in the photospheric
magnetic field measurements, influence the quality of the computed
coronal magnetic field model.

---------------------------------------------------------
Title: Relation between the Sunrise photospheric magnetic field and
the Ca II H bright features
Authors: Jafarzadeh, Shahin; Hirzberger, J.; Feller, A.; Lagg, A.;
Solanki, S. K.; Pietarila, A.; Danilovic, S.; Riethmueller, T.;
Barthol, P.; Berkefeld, T.; Gandorfer, A.; Knülker, M.; Martínez
Pillet, V.; Schmidt, W.; Schüssler, M.; Title, A.
2010cosp...38.2856J Altcode: 2010cosp.meet.2856J
Recent observations from the Sunrise balloon-borne solar telescope
have enabled us to reach an unprecedented high spatial resolution
on the solar surface with the near-ultraviolet photo-spheric and
chromospheric images as well as the magnetograms. We use these high
resolution observations to investigate the structure of the solar
upper photosphere and lower chromosphere as well as their temporal
evolutions. We study the relation between the inter-granular Ca II
397 nm bright structures in images obtained by the Sunrise Filter
Imager (SuFI) and their corresponding photospheric vector magnetic
field computed from the Imaging Magnetogram eXperiment (IMaX)
observations. The targets under study are in a quiet Sun region and
close to disc-centre.

---------------------------------------------------------
Title: Energetic particles in Saturn's magnetosphere during the
Cassini nominal mission (July 2004-July 2008)
Authors: Krupp, N.; Roussos, E.; Lagg, A.; Woch, J.; Müller, A. L.;
Krimigis, S. M.; Mitchell, D. G.; Roelof, E. C.; Paranicas, C.;
Carbary, J.; Jones, G. H.; Hamilton, D. C.; Livi, S.; Armstrong,
T. P.; Dougherty, M. K.; Sergis, N.
2009P&SS...57.1754K Altcode:
In July 2004 the Cassini spacecraft began its orbital tour in the
Saturnian system and performed 74 orbits during the nominal mission
(July 2004-July 2008) providing data from nearly all local times at
various distances and latitudes relative to the planet. The particles
and field instruments onboard the spacecraft were essentially operating
continuously offering the possibility to study the global configuration
and the dynamics of the second largest magnetosphere in our solar
system extensively. One of those instruments aboard Cassini is the Low
Energy Magnetospheric Measurement System (LEMMS), one of three particle
detectors of the Magnetospheric Imaging Instrument (MIMI). MIMI/LEMMS
measures the intensity, energy spectra and pitch angle distributions of
energetic ions (E&gt;30keV) and electrons (E&gt;20keV) separately. The
measured energetic particle distributions together with the measured
magnetic field provide a very powerful tool to investigate the
Saturnian magnetosphere in those regions covered by the Cassini
orbits. This paper will give an overview of the energetic particle
measurements of the MIMI/LEMMS sensor in the Saturnian system. In the
first part of the paper synoptic maps will be shown where all the data
are presented as a function of various trajectory parameters of the
spacecraft. Secondly bi-directional electron distributions along the
magnetic field direction will be described as a feature in the Saturnian
system. Thirdly the particle parameters in the inner magnetosphere with
absorption signatures of the various moons are presented. Fourthly it
will be shown that the region around about 15 RS seems to
be a characteristic region where depletion signatures in energetic
particle distributions are very often observed. At the end of this
work a 60 min intensity periodicity in the MIMI/LEMMS data is discussed.

---------------------------------------------------------
Title: Simulation of a flux emergence event and comparison with
observations by Hinode
Authors: Yelles Chaouche, L.; Cheung, M. C. M.; Solanki, S. K.;
Schüssler, M.; Lagg, A.
2009A&A...507L..53Y Altcode: 2009arXiv0910.5737Y
Aims: We study the observational signature of flux emergence in
the photosphere using synthetic data from a 3D MHD simulation of the
emergence of a twisted flux tube. Methods: Several stages in the
emergence process are considered. At every stage we compute synthetic
Stokes spectra of the two iron lines Fe I 6301.5 Å and Fe I 6302.5
Å and degrade the data to the spatial and spectral resolution of
Hinode's SOT/SP. Then, following observational practice, we apply
Milne-Eddington-type inversions to the synthetic spectra in order
to retrieve various atmospheric parameters and compare the results
with recent Hinode observations. Results: During the emergence
sequence, the spectral lines sample different parts of the rising
flux tube, revealing its twisted structure. The horizontal component
of the magnetic field retrieved from the simulations is close to the
observed values. The flattening of the flux tube in the photosphere is
caused by radiative cooling, which slows down the ascent of the tube
to the upper solar atmosphere. Consistent with the observations, the
rising magnetized plasma produces a blue shift of the spectral lines
during a large part of the emergence sequence. Figure 3 is only
available in electronic form at http://www.aanda.org

---------------------------------------------------------
Title: Internetwork Horizontal Magnetic Fields in the Quiet Sun
Chromosphere: Results from a Joint Hinode/VTT Study
Authors: Lagg, A.; Ishikawa, R.; Merenda, L.; Wiegelmann, T.; Tsuneta,
S.; Solanki, S. K.
2009ASPC..415..327L Altcode:
We present results from a joint Hinode/VTT campaign (May
2008). Spectropolarimetric data of a quiet Sun super-granular network
cell at a heliocentric angle of 28° in the He I 10830 Å line were
analyzed using an inversion code incorporating Hanle and Zeeman effects
(HeLIx^+) to retrieve magnetic field strength and direction in the upper
chromosphere. Simultaneously recorded Hinode SOT/SP data reveal the
photospheric magnetic field morphology, clearly showing magnetic flux
concentrations in the internetwork. The photospheric magnetic field
maps are used to feed potential field extrapolations similar to the
work by Schrijver &amp; Title (2003). The extrapolated magnetic field
structure is compared with the magnetic field configuration resulting
from the He 10830 inversions. These inversions also reveal horizontal
magnetic structures extending over a length of up to 20 Mm above the
internetwork, indicative of the presence of a magnetic canopy. The
photospheric magnetic flux concentrations in the internetwork are
obviously not sufficiently strong to prevent the formation of a canopy
at chromospheric heights.

---------------------------------------------------------
Title: High-resolution spectro-polarimetry of a flaring sunspot
penumbra
Authors: Hirzberger, J.; Riethmüller, T.; Lagg, A.; Solanki, S. K.;
Kobel, P.
2009A&A...505..771H Altcode: 2009arXiv0908.3803H
We present simultaneous photospheric and chromospheric observations
of the trailing sunspot in NOAA 10904 during a weak flare eruption
(GOES magnitude B7.8), obtained with the Swedish Solar Telescope
(SST) in La Palma, Canary Islands. High-resolution Ca II H images
show a typical two-ribbon structure that has been hitherto only
known for larger flares, and the flare appears in a confined region
that is discernible by a bright border. The underlying photosphere
shows a disturbed penumbral structure with intersecting branches of
penumbral filaments. High-resolution Doppler- and vector-magnetograms
exhibit oppositely directed Evershed flows and magnetic field vectors
in the individual penumbral branches, resulting in several regions
of magnetic azimuth discontinuity and several islands where the
vertical magnetic field is reversed. The discontinuity regions are
co-spatial with the locations of the onset of the flare ribbons. From
the results, we conclude that the confined flare region is detached
from the global magnetic field structure by a separatrix marked by the
bright border visible in C II H. We further conclude that the islands
of reversed vertical field appear because of flux emergence and that
the strong magnetic shear appearing in the regions of magnetic azimuth
discontinuity triggers the flare. Movies are only available in
electronic form at http://www.aanda.org

---------------------------------------------------------
Title: Full Magnetic Field Vector of an Emerging Flux Region
Authors: Xu, Z.; Lagg, A.; Solanki, S. K.
2009ASPC..405..223X Altcode:
We present maps of the full magnetic field vector of an emerging flux
region in both the photosphere and chromosphere. The magnetic and
velocity structure of freshly emerged loops is determined.

---------------------------------------------------------
Title: A summary of observational records on periodicities above
the rotational period in the Jovian magnetosphere
Authors: Kronberg, E. A.; Woch, J.; Krupp, N.; Lagg, A.
2009AnGeo..27.2565K Altcode:
The Jovian magnetosphere is a very dynamic system. The plasma
mass-loading from the moon Io and the fast planetary rotation lead
to regular release of mass from the Jovian magnetosphere and to
a change of the magnetic topology. These regular variations, most
commonly on several (2.5-4) days scale, were derived from various
data sets obtained by different spacecraft missions and instruments
ranging from auroral images to in situ measurements of magnetospheric
particles. Specifically, ion measurements from the Galileo spacecraft
represent the periodicities, very distinctively, namely the
periodic thinning of the plasma sheet and subsequent dipolarization,
and explosive mass release occurring mainly during the transition
between these two phases. We present a review of these periodicities,
particularly concentrating on those observed in energetic particle
data. The most distinct periodicities are observed for ions of sulfur
and oxygen. The periodic topological change of the Jovian magnetosphere,
the associated mass-release process and auroral signatures can be
interpreted as a global magnetospheric instability with analogies to
the two step concept of terrestrial substorms. Different views on the
triggering mechanism of this magnetospheric instability are discussed.

---------------------------------------------------------
Title: The Three-Dimensional Structure of Magnetic Fields and Electric
Currents in an Active Region
Authors: Deng, Na; Choudhary, D.; Lagg, A.; Jing, J.; Wang, H.
2009SPD....40.0904D Altcode:
Active Region NOAA 9661 consisting of various magnetic features (alpha
spot, delta spot, pores, and plages) was observed simultaneously
in three spectral lines (FeI 630.25, 630.15, and MgI 517.27) using
full Stokes spectro-polarimetry with Advanced Stokes Polarimeter at
NSO/SP. The formation heights of the three spectral lines span from
photosphere to the low chromosphere. The magnetic field vectors are
inverted from Stokes parameters using advanced inversion codes. In
particular, HeLIx code is used to invert MgI's observation because
it is dedicated for chromospheric Stokes inversion. The inverted
magnetic field vectors in multiple atmospheric layers enable us to
derive the three dimensional structure of the magnetic fields, electric
current densities, current helicities, and their height gradients. Acknowledgments: This work is supported by NASA under grants
NNX08AQ32G and NNX08AQ89G, and by NSF under grants ATM 05-48952 and
ATM 07-16950.

---------------------------------------------------------
Title: Coupling from the Photosphere to the Chromosphere and the
Corona
Authors: Wedemeyer-Böhm, S.; Lagg, A.; Nordlund, Å.
2009SSRv..144..317W Altcode: 2008SSRv..tmp..171W; 2008arXiv0809.0987W
The atmosphere of the Sun is characterized by a complex interplay of
competing physical processes: convection, radiation, conduction, and
magnetic fields. The most obvious imprint of the solar convection
and its overshooting in the low atmosphere is the granulation
pattern. Beside this dominating scale there is a more or less smooth
distribution of spatial scales, both towards smaller and larger
scales, making the Sun essentially a multi-scale object. Convection and
overshooting give the photosphere its face but also act as drivers for
the layers above, namely the chromosphere and corona. The magnetic field
configuration effectively couples the atmospheric layers on a multitude
of spatial scales, for instance in the form of loops that are anchored
in the convection zone and continue through the atmosphere up into
the chromosphere and corona. The magnetic field is also an important
structuring agent for the small, granulation-size scales, although
(hydrodynamic) shock waves also play an important role—especially in
the internetwork atmosphere where mostly weak fields prevail. Based on
recent results from observations and numerical simulations, we attempt
to present a comprehensive picture of the atmosphere of the quiet Sun
as a highly intermittent and dynamic system.

---------------------------------------------------------
Title: Zeeman Broadening in Cool Stars
Authors: Anderson, Richard I.; Reiners, Ansgar; Solanki, Sami K.;
Lagg, Andreas
2009AIPC.1094..708A Altcode: 2009csss...15..708A
We investigate detectability of magnetic fields by Zeeman broadening
of well-isolated spectral lines in F, G and K type stars. Data of
unprecedented quality were taken with CES1 mounted on the 3.6
m ESO telescope at La Silla, Chile, in three campaigns in the optical
range between 5770 Å and 6280 Å, each with a wavelength coverage
of roughly 40 Å. We use the SPINOR/STOPRO (cf. Frutiger et al. [1])
package developed by ETH2 and MPS3 to perform
spectral line inversion via χ2 minimization. Starting from
constraints given by previous measurements of stellar parameters,
we fit a number of extracted spectral lines. Eventually, our goal
is to determine the product of the magnetic field strength B and the
surface filling factor, B×f. Our work is in progress and thus
no final measurements can be presented at this stage.

---------------------------------------------------------
Title: Coupling from the Photosphere to the Chromosphere and the
Corona
Authors: Wedemeyer-Böhm, S.; Lagg, A.; Nordlund, Å.
2009odsm.book..317W Altcode:
The atmosphere of the Sun is characterized by a complex interplay of
competing physical processes: convection, radiation, conduction, and
magnetic fields. The most obvious imprint of the solar convection
and its overshooting in the low atmosphere is the granulation
pattern. Beside this dominating scale there is a more or less smooth
distribution of spatial scales, both towards smaller and larger
scales, making the Sun essentially a multi-scale object. Convection and
overshooting give the photosphere its face but also act as drivers for
the layers above, namely the chromosphere and corona. The magnetic field
configuration effectively couples the atmospheric layers on a multitude
of spatial scales, for instance in the form of loops that are anchored
in the convection zone and continue through the atmosphere up into
the chromosphere and corona. The magnetic field is also an important
structuring agent for the small, granulation-size scales, although
(hydrodynamic) shock waves also play an important role—especially in
the internetwork atmosphere where mostly weak fields prevail. Based on
recent results from observations and numerical simulations, we attempt
to present a comprehensive picture of the atmosphere of the quiet Sun
as a highly intermittent and dynamic system.

---------------------------------------------------------
Title: CRISP Spectropolarimetric Imaging of Penumbral Fine Structure
Authors: Scharmer, G. B.; Narayan, G.; Hillberg, T.; de la Cruz
Rodriguez, J.; Löfdahl, M. G.; Kiselman, D.; Sütterlin, P.; van
Noort, M.; Lagg, A.
2008ApJ...689L..69S Altcode: 2008arXiv0806.1638S
We discuss penumbral fine structure in a small part of a pore,
observed with the CRISP imaging spectropolarimeter at the Swedish
1-m Solar Telescope (SST), close to its diffraction limit of
0.16”. Milne-Eddington inversions applied to these Stokes data
reveal large variations of field strength and inclination angle over
dark-cored penumbral intrusions and a dark-cored light bridge. The
mid-outer part of this penumbra structure shows ~0.3” wide spines,
separated by ~1.6” (1200 km) and associated with 30° inclination
variations. Between these spines, there are no small-scale magnetic
structures that easily can be identified with individual flux tubes. A
structure with nearly 10° more vertical and weaker magnetic field is
seen midway between two spines. This structure is cospatial with the
brightest penumbral filament, possibly indicating the location of a
convective upflow from below.

---------------------------------------------------------
Title: Mass release process in the Jovian magnetosphere: Statistics
on particle burst parameters
Authors: Kronberg, E. A.; Woch, J.; Krupp, N.; Lagg, A.
2008JGRA..11310202K Altcode:
The Jovian magnetosphere undergoes periodic reconfiguration processes
mainly driven by the fast planetary rotation and mass loading from the
moon Io. These reconfiguration processes of the Jovian magnetosphere
are associated with the release of plasmoids discernible as ion flow
bursts associated with bipolar magnetic signatures. We investigate
these plasma flows statistically using data from the Energetic Particles
Detector and from the magnetometer on board Galileo. The plasma flows
are observed in different magnetospheric regions: the current sheet
center, the plasma sheet boundary layers, and the lobe. We show that
the bulk velocity of all species is the same for most of the magnetic
field bipolar signatures associated with these plasma flows. The average
speed of the observed plasmoids in the plasma sheet associated with
the ion flow bursts is between 350 and 500 km s-1, and
the duration of the events is between 10 and 20 min. The associated
plasmoid length is correspondingly ∼9 RJ. The plasmoids
are moving approximately with Alfvénic speed. The convection electric
field during the plasmoid release is about an order of magnitude higher
than the ambient value of the Jovian convection electric field.

---------------------------------------------------------
Title: Loop Morphology and Flows and their Relation to the Magnetic
Field
Authors: Teriaca, L.; Wiegelmann, T.; Lagg, A.; Solanki, S. K.; Curdt,
W.; Sekii, T.
2008ASPC..397..196T Altcode:
In November 2006 we obtained several rasters of a large sunspot
and its trailing region using the SUMER spectrometer on SOHO. The
observations consist of spectroheliograms in the continuum around
142 nm and in several spectral lines formed between 80000 K and
0.6 MK, covering the temperature range from the chromosphere to
the lower corona. The observed profiles provide LOS velocity and
Doppler width maps. TRACE images in the EUV passbands and in the 160
nm continuum provide a clear picture of the coronal loops and the
chromosphere near their footpoints. The same target was also observed
by all the instruments aboard Hinode and, in particular, by the SOT
spectro-polarimeter measuring the photospheric magnetic vector. We
combined SOT and MDI data (covering a larger FOV) to infer the coronal
magnetic field of the active region by a nonlinear force-free field
extrapolation. The observed radiance and velocity patterns at the
various heights/temperatures throughout the solar atmosphere are
compared with the field topology.

---------------------------------------------------------
Title: The Magnetic Vector Structure of an Active Region Plage Field
Authors: Meling, M. H. M.; Lagg, A.; Solanki, S. K.
2008ESPM...12.2.58M Altcode:
We present scans of the active region plage associated with NOAA 10953,
recorded with the Tenerife Infrared Polarimeter 2 (TIP-2) mounted
behind the German Vacuum Tower Telescope (VTT) on Tenerife and the
SOT-SP instrument on-board the HINODE spacecraft. TIP-2 recorded the
full Stokes vector close to the diffraction limit of the telescope over
a 20 angstroem wavelength range containing six magnetically sensitive
FeI lines in the infrared including the g=3 line FeI 15648.5. With
these lines we use the advantage that the Zeeman splitting dominates
over the Doppler broadening for kG fields. The iron lines used by
HINODE are FeI 6301.501and FeI 6302.494. We analyzed the data by
applying a Milne-Eddington type inversion to it. In the context of a
two-component model we found a bimodal distribution of field strengths,
strong fields whose field strength distribution peaks at 1400 [G]
and a weak field distribution, which may be associated with quiet sun
regions bordering on the plage.

---------------------------------------------------------
Title: SST/CRISP Magnetometry with Fe I 630.2 nm
Authors: Narayan, G.; Scharmer, G. B.; Hillberg, T.; Lofdahl, M.;
van Noort, M.; Sutterlin, P.; Lagg, A.
2008ESPM...122.120N Altcode:
We present recent full Stokes observations in the Fe I 630.2 nm
line with CRISP, an imaging spectropolarimeter at the Swedish 1-m
Solar Telescope (SST). The observations reach a spatial resolution
of 0".16, close to the diffraction limit of the SST, representing
a major improvement over any past ground based or space based
spectropolarimetric data. We describe the data acquisition and reduction
methods and present results of Milne-Eddington(ME) inversions applied
on observations of plage.

---------------------------------------------------------
Title: Magnetic Structure of a Filament during its Phase of Activity
Authors: Sasso, C.; Lagg, A.; Solanki, S. K.
2008ESPM...12.2.19S Altcode:
We analyze and interpret spectropolarimetric observations of an active
region filament located close to the solar disc center, during its
phase of activity. The observations are obtained in the chromospheric
He I lines at 1083.0 nm. We provide novel observational results on the
magnetic field measurements in solar filaments to give constraints
to the theoretical models of their support in the solar corona. Our
main goal is to interpret the behavior of the atmospheric parameters
retrieved from the spectropolarimetric data to give a picture of
the magnetic structure of the observed filament. The analysis of the
observed polarization of the He I 1083.0 nm multiplet in the filament,
carried out by inverting the Stokes profiles, reveals the presence of
different unresolved atmospheric components of the He lines, coexisting
within the resolution element (1.2 arcsec). The different components,
belonging to different magnetic field lines, show supersonic up-
and downflows, sometimes within the same resolution element. The He
blueshifted components belong to mostly transversal field lines in
the body of the filament. These field lines are found to be curving
upwards on both sides. This picture suggests the presence of dipped
field lines that are moving upward, carrying with them the filament
material. During this movement, we also observe filament material
flowing down along field lines having the same polarity as the
photospheric field (i.e. they have the opposite inclination with
respect to the dipped field lines). These downflows are faster at the
filament end points and can reach values close to 10 times the speed of
sound. The field lines are found to be almost parallel to the filament
axis in the plane perpendicular to the line of sight. We use the two
main theoretical models of prominence support (dip or flux rope models)
to interpret the results obtained.

---------------------------------------------------------
Title: The intensity contrast of solar granulation: comparing Hinode
SP results with MHD simulations
Authors: Danilovic, S.; Gandorfer, A.; Lagg, A.; Schüssler, M.;
Solanki, S. K.; Vögler, A.; Katsukawa, Y.; Tsuneta, S.
2008A&A...484L..17D Altcode: 2008arXiv0804.4230D
Context: The contrast of granulation is an important quantity
characterizing solar surface convection. Aims: We compare the
intensity contrast at 630 nm, observed using the Spectro-Polarimeter
(SP) aboard the Hinode satellite, with the 3D radiative MHD simulations
of Vögler &amp; Schüssler (2007, A&amp;A, 465, L43). Methods:
A synthetic image from the simulation is degraded using a theoretical
point-spread function of the optical system, and by considering other
important effects. Results: The telescope aperture and the
obscuration by the secondary mirror and its attachment spider, reduce
the simulated contrast from 14.4% to 8.5%. A slight effective defocus
of the instrument brings the simulated contrast down to 7.5%, close to
the observed value of 7.0%. Conclusions: A proper consideration
of the effects of the optical system and a slight defocus, lead to
sufficient degradation of the synthetic image from the MHD simulation,
such that the contrast reaches almost the observed value. The remaining
small discrepancy can be ascribed to straylight and slight imperfections
of the instrument, which are difficult to model. Hence, Hinode SP data
are consistent with a granulation contrast which is predicted by 3D
radiation MHD simulations.

---------------------------------------------------------
Title: Multiheight Analysis of Asymmetric Stokes Profiles in a Solar
Active Region
Authors: Deng, N.; Choudhary, D.; Solanki, S. K.; Lagg, A.
2008AGUSMSP51D..06D Altcode:
Parameters characterizing Stokes asymmetries are derived from full
Stokes I,Q,U,V spectra of FeI λλ 630.15, 630.25~nm line pair
(formed at two different heights in the photosphere) and MgI b
517.27~nm line (formed at lower chromosphere) in a solar active
region near disc center. The spectropolarimetric observations were
taken with the National Solar Observatory/High Altitude Observatory
Advanced Stokes Polarimeter. The observed active region consists
of a α sunspot, a δ sunspot, several pores and granulation. The
line center shifts and bi-sectors derived from Stokes-I profiles
describe the line-of-sight Doppler velocity and Stokes-I asymmetry,
respectively. Stokes-V amplitude and area asymmetries are defined by
the normalized difference of respective quantities between blue and
red lobes of circular polarization profiles. The same can be derived
from linear polarization profiles ([Q2+U2]1/2). The Stokes asymmetries
are compared for different regions and at multiple heights. Neutral
line regions of the δ spot and outer penumbral regions show distinct
large Stokes asymmetries. Both Stokes-V amplitude and area asymmetries
become larger from lower to higher atmosphere in neutral line regions
that have strong transverse field and mixed polarities. The Stokes-V
area asymmetry of outer edge of penumbrae changes from positive in
the photosphere to negative in lower chromosphere. Detailed results
and interpretation will be presented.

---------------------------------------------------------
Title: The nature of running penumbral waves revealed
Authors: Bloomfield, D. S.; Lagg, A.; Solanki, S. K.
2008IAUS..247...55B Altcode: 2007IAUS..247...55B
We seek to clarify the nature of running penumbral (RP) waves:
are they chromospheric trans-sunspot waves or a visual pattern of
upward-propagating waves? Full Stokes spectropolarimetric time series
of the photospheric Sii10827 Å line and the chromospheric Hei10830 Å
multiplet were inverted using a Milne-Eddington code. Spatial pixels
were paired between the outer umbral/inner penumbral photosphere
and the penumbral chromosphere using inclinations retrieved by the
inversion and the dual-height pairings of line-of-sight velocity time
series were studied for signatures of wave propagation using a Fourier
phase difference analysis. The dispersion relation for radiatively
cooling acoustic waves, modified to incorporate an inclined propagation
direction, fits well the observed phase differences between the pairs
of photospheric and chromospheric pixels. We have thus demonstrated
that RP waves are in effect low-β slow-mode waves propagating along
the magnetic field.

---------------------------------------------------------
Title: Stratification of Sunspot Umbral Dots from Inversion of Stokes
Profiles Recorded by Hinode
Authors: Riethmüller, T. L.; Solanki, S. K.; Lagg, A.
2008ApJ...678L.157R Altcode: 2008arXiv0805.4324R
This work aims to constrain the physical nature of umbral dots (UDs)
using high-resolution spectropolarimetry. Full Stokes spectra recorded
by the spectropolarimeter on Hinode of 51 UDs in a sunspot close to the
disk center are analyzed. The height dependence of the temperature,
magnetic field vector, and line-of-sight velocity across each UD
is obtained from an inversion of the Stokes vectors of the two Fe I
lines at 630 nm. No difference is found at higher altitudes [-3 &lt;=
log (τ500) &lt;= - 2] between the UDs and the diffuse
umbral background. Below that level the difference rapidly increases,
so that at the continuum formation level [log (τ500) = 0]
we find on average a temperature enhancement of 570 K, a magnetic field
weakening of 510 G, and upflows of 800 m s-1 for peripheral
UDs, whereas central UDs display an excess temperature of on average
550 K, a field weakening of 480 G, and no significant upflows. The
results for, in particular, the peripheral UDs, including cuts of
magnetic vector and velocity through them, look remarkably similar to
the output of recent radiation MHD simulations. They strongly suggest
that UDs are produced by convective upwellings.

---------------------------------------------------------
Title: The FeH F4Δ-X4Δ system. Creating a
valuable diagnostic tool to explore solar and stellar magnetic fields
Authors: Afram, N.; Berdyugina, S. V.; Fluri, D. M.; Solanki, S. K.;
Lagg, A.
2008A&A...482..387A Altcode:
Context: Lines of diatomic molecules are ideal tools for studying
cool stellar atmospheres and the internal structure of sunspots
and starspots, given their temperature and pressure sensitivities,
which are typically higher than in atomic lines. The Wing-Ford FeH
F4Δ-X4Δ system represents such a diatomic
molecule that is, in addition, highly sensitive to magnetic fields. The
current theoretical description of those transitions that include the
involved molecular constants, however, are only based on intensity
measurements because polarimetric observations have not been available
until now, which limits their diagnostic value. Furthermore, the theory
has so far been optimized to reproduce energy levels and line strengths
without taking magnetic sensitivities into account. Aims: The
FeH F4Δ-X4Δ system is produced by transitions
between two electronic states with the coupling of the angular momenta
that is intermediate between limiting Hund's cases (a) and (b). Our goal
is to investigate the diagnostic capabilities of the current theoretical
description of the molecule FeH. Methods: Using the most precise
available Hamiltonian, we carried out the perturbation calculation
of the molecular Zeeman effect for this transition and computed the
Landé factors of the energy levels and of transitions. We extracted
Landé factors from a comparison of observed and calculated Stokes
I and V profiles. Certain spectral lines, most frequently with high
magnetic sensitivity, exhibited discrepancies between the theory and
observations. We extended the theoretical model with a semi-empirical
approach to obtain a diagnostic tool that is able to reproduce many
of the interesting spectral lines. Results: We find that the
current theory successfully reproduces the magnetic properties of
a large number of lines in the FeH F4Δ-X4Δ
system and that the modified Hamiltonian allows us to synthesize
and successfully reproduce the most sensitive lines. Thus, our
observations have provided valuable constraints for determining
empirical molecular constants and Landé factors. Conclusions:
The FeH F4Δ-X4Δ system is found to be a very
sensitive magnetic diagnostic tool. Polarimetric data of these lines,
in contrast to intensity measurements, provide us with more direct
and detailed information to study the coolest parts of sunspot and
starspot umbrae, as well as cool active dwarfs.

---------------------------------------------------------
Title: Comparison of periodic substorms at Jupiter and Earth
Authors: Kronberg, E. A.; Woch, J.; Krupp, N.; Lagg, A.; Daly, P. W.;
Korth, A.
2008JGRA..113.4212K Altcode:
The Energetic Particles Detector and magnetometer measurements on
Galileo showed that the Jovian magnetosphere undergoes reconfiguration
processes which are very similar to the characteristics of a
terrestrial substorm. At Jupiter the reconfiguration process occurs
quasi-periodically with a repetition period of several days. In
the terrestrial magnetosphere periodic substorms have been observed
during magnetic storms. The comparison of the periodic magnetospheric
disturbances at Jupiter and Earth shows that they are similar in dynamic
features as well as in spatial distribution but have different energy
sources. In the case of Earth, the well-established energy source is
the solar wind. In the case of the Jovian magnetosphere, it is believed
that internal energy is supplied by the fast planetary rotation and
the moon Io which releases ∼1000 kg s-1 of plasma into
the magnetosphere. It is established that the energy accumulation and
subsequent release lead to similar features in the magnetospheres of
both planets. The particle data show periodic intensity fluctuations
and plasma pressure variations. In addition, recurring signatures of
stretching and dipolarization are observed in the magnetic field at
the terrestrial and Jovian magnetospheres. Furthermore, the release
process is associated with an intensification of auroral emissions. The
typical phases for terrestrial substorms like growth, expansion and
recovery are also found in the periodic substorms at Jupiter. As a
lesson taken from the Jovian magnetosphere it is proposed that under
certain conditions periodic magnetospheric substorms at Earth can be
driven by mass-loading from the plasmasphere.

---------------------------------------------------------
Title: The Dust Halo of Saturn’s Largest Icy Moon, Rhea
Authors: Jones, G. H.; Roussos, E.; Krupp, N.; Beckmann, U.;
Coates, A. J.; Crary, F.; Dandouras, I.; Dikarev, V.; Dougherty,
M. K.; Garnier, P.; Hansen, C. J.; Hendrix, A. R.; Hospodarsky,
G. B.; Johnson, R. E.; Kempf, S.; Khurana, K. K.; Krimigis, S. M.;
Krüger, H.; Kurth, W. S.; Lagg, A.; McAndrews, H. J.; Mitchell,
D. G.; Paranicas, C.; Postberg, F.; Russell, C. T.; Saur, J.; Seiß,
M.; Spahn, F.; Srama, R.; Strobel, D. F.; Tokar, R.; Wahlund, J. -E.;
Wilson, R. J.; Woch, J.; Young, D.
2008Sci...319.1380J Altcode:
Saturn’s moon Rhea had been considered massive enough to retain a
thin, externally generated atmosphere capable of locally affecting
Saturn’s magnetosphere. The Cassini spacecraft’s in situ
observations reveal that energetic electrons are depleted in the
moon’s vicinity. The absence of a substantial exosphere implies
that Rhea’s magnetospheric interaction region, rather than being
exclusively induced by sputtered gas and its products, likely contains
solid material that can absorb magnetospheric particles. Combined
observations from several instruments suggest that this material is
in the form of grains and boulders up to several decimetres in size
and orbits Rhea as an equatorial debris disk. Within this disk may
reside denser, discrete rings or arcs of material.

---------------------------------------------------------
Title: Energetic electron signatures of Saturn's smaller moons:
Evidence of an arc of material at Methone
Authors: Roussos, E.; Jones, G. H.; Krupp, N.; Paranicas, C.; Mitchell,
D. G.; Krimigis, S. M.; Woch, J.; Lagg, A.; Khurana, K.
2008Icar..193..455R Altcode:
We present several energetic charged particle microsignatures of
two Lagrange moons, Telesto and Helene, measured by the MIMI/LEMMS
instrument. These small moons absorb charged particles but their
effects are usually obscured by Tethys and Dione, the two larger
saturnian satellites that occupy the same orbits. The scales and
structures of these microsignatures are consistent with standard
models for electron absorption from asteroid-sized moons in Saturn's
radiation belts. In the context of these observations, we also examine
the possibility that the 3 km Satellite Methone is responsible for
two electron microsignatures detected by Cassini close to this moon's
orbit. We infer that a previously undetected arc of material exists
at Methone's orbit (R/2006 S5), we speculate how such a structure
could form and what its physical characteristics and location could
be. The origin of this arc could be linked to a possible presence of
a faint ring produced by micrometeoroid impacts on Methone's surface,
to E-ring dust clump formation at that distance or to temporary dust
clouds produced by enceladian activity that spiral inwards under the
effect of non-gravitational forces.

---------------------------------------------------------
Title: The Nature of Running Penumbral Waves Revealed
Authors: Bloomfield, D. Shaun; Lagg, Andreas; Solanki, Sami K.
2007ApJ...671.1005B Altcode: 2007arXiv0709.3731B
We seek to clarify the nature of running penumbral (RP) waves:
are they chromospheric trans-sunspot waves or a visual pattern of
upward-propagating waves? Full Stokes spectropolarimetric time series of
the photospheric Si I λ10827 line and the chromospheric He I λ10830
multiplet were inverted using a Milne-Eddington atmosphere. Spatial
pixels were paired between the outer umbral/inner penumbral photosphere
and the penumbral chromosphere using inclinations retrieved by the
inversion and the dual-height pairings of line-of-sight velocity time
series were studied for signatures of wave propagation using a Fourier
phase difference analysis. The dispersion relation for radiatively
cooling acoustic waves, modified to incorporate an inclined propagation
direction, fits well the observed phase differences between the pairs
of photospheric and chromospheric pixels. We have thus demonstrated
that RP waves are in effect low-β slow-mode waves propagating along
the magnetic field.

---------------------------------------------------------
Title: Rhea's interaction with Saturn's magnetosphere
Authors: Jones, G. H.; Roussos, E.; Krupp, N.; Beckmann, U.; Coates,
A. J.; Crary, F.; Dandouras, I.; Dikarev, V.; Dougherty, M. K.;
Garnier, P.; Hansen, C. J.; Hendrix, A. R.; Hospodarsky, G. B.;
Johnson, R. E.; Kempf, S.; Khurana, K.; Krimigis, S. M.; Krueger, H.;
Kurth, W. S.; Lagg, A.; McAndrews, H. J.; Mitchell, D. G.; Paranicas,
C.; Postberg, F.; Russell, C. T.; Saur, J.; Seiss, M.; Spahn, F.;
Srama, R.; Strobel, D. F.; Tokar, R. L.; Wahlund, J.; Wilson, R. J.;
Woch, J.; Young, D.
2007AGUFM.P12B..05J Altcode:
The instruments aboard the Cassini orbiter continue to provide a
wealth of invaluable information on plasma interactions at the icy
moons of Saturn. 1528 km-wide Rhea is the largest of Saturn's icy
satellites. Here, we present our analysis of data from the two closest
flybys of this moon to date, in November 2005 and August 2007. Data from
six Cassini instruments are presented; MIMI, CAPS, MAG, RPWS, UVIS,
and CDA, covering the plasma, neutral gas, and dust environments of
the moon. The complementary information provided by these instruments
allows us to draw a picture of this moon's intriguing interaction
with Saturn's magnetospheric plasma. We compare the results at Rhea
to those obtained at other moons, and we present our arguments for the
causes of variations observed in the magnetospheric electron population.

---------------------------------------------------------
Title: Energetic charged particle absorption by Saturn's icy moons:
future studies and new applications
Authors: Roussos, E.; Krupp, N.; Jones, G. H.; Paranicas, C.; Mitchell,
D. G.; Krimigis, S. M.; Motschmann, U.; Lagg, A.; Woch, J.
2007epsc.conf..905R Altcode:
Energetic charged particle absorption signatures by Saturn's large
icy moons, rings and dust are an excellent tool for the study of
the planet's magnetospheric dynamics and dust environment. After the
first two years of the Cassini mission, relevant observations with the
MIMI/LEMMS energetic electron sensors extended and updated the results
from previous studies that used data from experiments on the Pioneer
11 and the Voyager missions. The new results include values for the
radial diffusion coefficients and their L-dependence, the observation
of the non-axisymmetric structure of the electron drift shells, as
well as the detection and the physical characterization of ring arcs
at Methone's orbit and the G-ring. Furthermore, these results reveal
that the information coded in charged particle absorption signatures
is even greater than we could initially imagine: the highly variable
lifetimes of electron microsignatures suggest a possible link with
equally variable dynamic events, such as injections. The shape
of the electron drift shells seems consistent with the effect of
magnetospheric compression on the dayside, meaning that information
about the magnetopause distance might be hidden in the absorption
signature locations. The microsignature locations during high-latitude,
close moon flybys, can also reveal the shape of the magnetic field lines
and be used to ”calibrate" magnetic field models. Such observations
could be crucial for the understanding of the magnetospheric and the
space environment of Saturn.

---------------------------------------------------------
Title: Modified p-modes in penumbral filaments?
Authors: Bloomfield, D. S.; Solanki, S. K.; Lagg, A.; Borrero, J. M.;
Cally, P. S.
2007A&A...469.1155B Altcode: 2007arXiv0705.0481B
Aims:The primary objective of this study is to search for and identify
wave modes within a sunspot penumbra. Methods: Infrared
spectropolarimetric time series data are inverted using a model
comprising two atmospheric components in each spatial pixel. Fourier
phase difference analysis is performed on the line-of-sight velocities
retrieved from both components to determine time delays between the
velocity signals. In addition, the vertical separation between the
signals in the two components is calculated from the Stokes velocity
response functions. Results: The inversion yields two atmospheric
components, one permeated by a nearly horizontal magnetic field, the
other with a less-inclined magnetic field. Time delays between the
oscillations in the two components in the frequency range 2.5-4.5 mHz
are combined with speeds of atmospheric wave modes to determine wave
travel distances. These are compared to expected path lengths obtained
from response functions of the observed spectral lines in the different
atmospheric components. Fast-mode (i.e., modified p-mode) waves exhibit
the best agreement with the observations when propagating toward the
sunspot at an angle ~50° to the vertical.

---------------------------------------------------------
Title: Electron microdiffusion in the Saturnian radiation belts:
Cassini MIMI/LEMMS observations of energetic electron absorption by
the icy moons
Authors: Roussos, E.; Jones, G. H.; Krupp, N.; Paranicas, C.; Mitchell,
D. G.; Lagg, A.; Woch, J.; Motschmann, U.; Krimigis, S. M.; Dougherty,
M. K.
2007JGRA..112.6214R Altcode: 2007JGRA..11206214R
Since Saturn orbit insertion (SOI), Cassini has performed numerous
crossings of Saturn's inner moons' L shells. The Low-Energy
Magnetospheric Measurement System (LEMMS) has detected a large number
of microsignatures in its lowest-energy electron channels (20-100 keV)
as well as in the MeV energy range. We have catalogued and analyzed more
than 70 microsignatures in the LEMMS data from the first 22 Cassini
orbits and have correlated their evolution with electron diffusive
processes. Our results on the L-dependence of the radial diffusion
coefficients, DLL, show that radial microdiffusion driven
by magnetic field impulses is the dominant mechanism to account for
their refilling. The dependency of DLL from equatorial
pitch angles also points toward this mechanism. The large scattering of
the DLL values at Tethys and Dione suggest that these field
impulses might be related to injections. Our analysis also supports the,
inferred from pre-Cassini studies, filtering effect by the icy moons
on radially diffusing electrons, which starts at the orbit of Dione,
at 6.28 Saturn radii, Rs. This is suggested primarily by
the very low radial diffusion speeds and by the characteristics of four
microsignatures attributed to the moons Mimas and Epimetheus that all
seem to have been formed in energies between 1.6 and 3.5 MeV. Despite
the low DLL, diffusing electrons can escape absorption and
be transported in the inner magnetosphere due to nonaxisymmetric drift
shells, which can be detected even along the orbit of Enceladus. We
estimate that a significant contribution to the filtering comes from
the core of the E ring. Our results also show that L displacements due
to the nonaxisymmetric drift shells are orders of magnitude higher than
the icy moon L shell variability due to the nonzero eccentricities and
inclinations, and total plasma losses on the moon surfaces should be
reevaluated. We also examine the energy dependence of DLL and
we present a series of possible explanations for the faster depletion
of microsignatures at MeV energies. Using the high-energy resolution
PHA channels we assess that this faster depletion could result partly
from an increase of DLL with energy. The larger passbands
of the high-energy electron detectors could amplify the erosion of
the microsignature signal.

---------------------------------------------------------
Title: Energetic ion composition during reconfiguration events in
the Jovian magnetotail
Authors: Radioti, A.; Woch, J.; Kronberg, E. A.; Krupp, N.; Lagg,
A.; Glassmeier, K. -H.; Dougherty, M. K.
2007JGRA..112.6221R Altcode: 2007JGRA..11206221R
On the basis of the first 15 orbits of the Galileo spacecraft
the composition of the energetic ion population of the Jovian
magnetosphere is studied on a global scale. Analyzing data from the
energetic particles detector onboard Galileo, we study the relative ion
abundance ratios of S/O, S/He, O/He and p/He at various energy/nucleon
values. Prominent enhancements of S/O, S/He, and O/He abundance ratios
are observed in the predawn sector and are associated with substorm-like
events in the Jovian magnetotail. During these reconfiguration
events, frequent small-scale variations of the south-north component
of the magnetic field are present. Acceleration by such magnetic
field variations is examined as a possible mechanism for particle
energization in that region. When the timescale of the magnetic field
variation is comparable to the particle gyro period, the particle is
accelerated by the induced electric field. It is shown that, during
the Jovian substorm-like events, the heavier ions are more efficiently
energized than the lighter leading to the observed ion abundances. Ion
composition measurements in other parts of the magnetosphere have shown
quasiperiodic 3-day modulations suggesting that the internally driven
processes affect the ion composition in the whole magnetosphere.

---------------------------------------------------------
Title: Observations of Running Waves in a Sunspot Chromosphere
Authors: Bloomfield, D. S.; Lagg, A.; Solanki, S. K.
2007ASPC..368..239B Altcode: 2007astro.ph..2056B
Spectropolarimetric time series data of the primary spot of active
region NOAA 9448 were obtained in the Si I 10827 Å line and the He I
10830 Å multiplet with the Tenerife Infrared Polarimeter. Throughout
the time series the spectrograph slit was fixed over a region covering
umbra, a light bridge, penumbra, and quiet sun. We present speeds
of running penumbral waves in the chromosphere, their relation to
both photospheric and chromospheric umbral oscillations, and their
dependence on the magnetic field topology.

---------------------------------------------------------
Title: Tenerife Infrared Polarimeter II
Authors: Collados, M.; Lagg, A.; Díaz Garcí A, J. J.; Hernández
Suárez, E.; López López, R.; Páez Mañá, E.; Solanki, S. K.
2007ASPC..368..611C Altcode:
Since May 2005 the Tenerife Infrared Polarimeter II (TIP-II) has been
operational at the Vacuum Tower Telescope on Tenerife. The core of the
polarimeter is a 1024×1020 pixel infrared camera allowing for high
precision measurements of the full Stokes vector with a pixel size of
0.18 arcsec, corresponding to the diffraction limit of the telescope at
1 μm. The polarimeter is able to reach a polarimetric accuracy of a few
times 10-4, covering a wavelength range of 1 to 1.8 μm. With
an upgrade in July 2006, the slit size has been increased to 77 arcsec
allowing most active regions to be covered with a single scan. Here
we present the technical details of the polarimeter and the camera. We
also show some data illustrating the power of this new instrumentation.

---------------------------------------------------------
Title: A possible intrinsic mechanism for the quasi-periodic dynamics
of the Jovian magnetosphere
Authors: Kronberg, E. A.; Glassmeier, K. -H.; Woch, J.; Krupp, N.;
Lagg, A.; Dougherty, M. K.
2007JGRA..112.5203K Altcode: 2007JGRA..11205203K
Most regions of the Jovian magnetosphere covered by the Galileo
spacecraft measurements undergo quasi-periodic modulations with a time
period of several Earth days. These modulations appear in various field
and particle properties. Most prominent are periodically recurring ion
flow bursts associated with disturbances in the meridional component
of the magnetic field in the Jovian magnetotail or variations of
the energy spectral shape of the particle distribution associated
with the stretching and dipolarization of the magnetic field. Each
individual cycle of these modulations is believed to represent a
global reconfiguration of the Jovian magnetosphere. We present a
simple conceptual model for these periodic processes assuming (1)
ion mass loading from internal plasma sources and (2) fast planetary
rotation causing magnetotail field line stretching due to centrifugal
forces. This leads to a magnetotail configuration favoring magnetic
reconnection. Magnetic reconnection causes plasmoid formation and
release as well as dipolarization of field lines connected to the
planet. Continued mass loading leads again to a stretching of the tail
field lines. Our model shows that the suggested intrinsic mechanism
can explain the observed periodicities of several days in Jovian
substorm-like processes.

---------------------------------------------------------
Title: Full-Stokes Observations and Analysis of He I 10830 Å in a
Flaring Region
Authors: Sasso, C.; Lagg, A.; Solanki, S. K.; Aznar Cuadrado, R.;
Collados, M.
2007ASPC..368..467S Altcode:
We present observations of the full Stokes vector in a flaring
region, taken in the chromospheric He I 10830 Å multiplet. The data
were recorded with the new Tenerife Infrared Polarimeter (TIP 2)
at the German Vacuum Tower Telescope (VTT) during May 2005. The He
profiles during the flare are extraordinary, showing extremely broad
Stokes I absorption and very complex and spatially variable Stokes V
signatures. We give first results on the line-of-sight velocities and
the magnetic field vector values in the chromosphere for one observed
Stokes profile by applying an inversion code to the He I lines.

---------------------------------------------------------
Title: Dynamics of the Jovian Magnetosphere
Authors: Krupp, N.; Vasyliunas, V. M.; Woch, J.; Lagg, A.; Khurana,
K. K.; Kivelson, M. G.; Mauk, B. H.; Roelof, E. C.; Williams, D. J.;
Krimigis, S. M.; Kurth, W. S.; Frank, L. A.; Patterson, W. R.
2007jupi.book..617K Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Configuration of Jupiter's Magnetosphere
Authors: Khurana, K. K.; Kivelson, M. G.; Vasyliunas, V. M.; Krupp,
N.; Woch, J.; Lagg, A.; Mauk, B. H.; Kurth, W. S.
2007jupi.book..593K Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Supersonic downflows in the vicinity of a growing
pore. Evidence of unresolved magnetic fine structure at chromospheric
heights
Authors: Lagg, A.; Woch, J.; Solanki, S. K.; Krupp, N.
2007A&A...462.1147L Altcode:
Aims:The velocity and magnetic fine structure of the chromosphere at
the leg of an emerging magnetic loop is investigated at a location
of supersonic downflows. Methods: We analyze a time series of
spectropolarimetric data in the He i 1083 nm triplet covering a time
interval of ≈70 min. The temporal evolution as well as the topology
of the magnetic field in the downflow region are investigated. We
apply an inversion technique based on a genetic algorithm using the
Milne-Eddington approach. The technique is very reliable and robust in
retrieving maps of the velocity and the magnetic field vector for both
atmospheric components separately. Results: We observe redshifts
corresponding to a downflow speed of up to 40 km s-1 in the
vicinity of a growing pore. These supersonic downflows always coexist
with a second atmospheric component almost at rest (slow component)
within the same resolution element. The redshifted component is more
inclined to the solar normal than the slow component and has a different
field strength. Conclusions: .We interpret this downflow as a
consequence of the draining of the rising loops. The different magnetic
field orientation of the redshifted and the slow component give rise to
two possible interpretations: an uncombed structure of the chromosphere,
similar to the differently inclined flux-tubes in the penumbra of
a sunspot, or a cloud-like structure containing gas at different
velocities in two separate height layers of the solar atmosphere.

---------------------------------------------------------
Title: Recent advances in measuring chromospheric magnetic fields
in the He I 10830 Å line
Authors: Lagg, A.
2007AdSpR..39.1734L Altcode:
During the last decade advances in instrumentation, atomic physics and
modeling have greatly improved the access to the chromospheric magnetic
field vector. High sensitivity polarimeters like the Tenerife Infrared
Polarimeter (TIP2, VTT) or the Spectro-Polarimeter for Infrared and
Optical Regions (SPINOR, HAO) lead to reliable Zeeman measurements
using the He I 10830 Å triplet. The simultaneously measured Si I
10827 Å line provides additional information on the structure of
the underlying photosphere. Theoretical modeling of the Hanle and the
Paschen-Back effect helped to significantly improve the analysis of
polarization measurements in the He I triplet, allowing to directly
visualize the magnetic structure of spicules, polar prominences and
active regions. Here, I will summarize the results of chromospheric
magnetic field measurements using this interesting triplet obtained
in the last couple of years and discuss the great potential it has
to further uncover the complex structure of the chromosphere and its
coupling to the photosphere.

---------------------------------------------------------
Title: T he Performance Of The SOLO-VIM Instrument: Effects Of
Instrumental Noise And Lossy Data Compression
Authors: Lagg, A.; Yelles, L.; Hirzberger, J.; Woch, J.; Solanki, S. K.
2007ESASP.641E..69L Altcode:
Spectropolarimetric observations in photospheric lines reveal a
wealth of information on physical parameters of the solar atmosphere
like magnetic field strength and di rection or the line-of sight
velocity. These observations require the measurement of the four Stokes
parameters at a sample of N wavelength positions around the core of the
spectral line, resulting in 4N images for one observation. The Visible
light Imager and Magnetograph (VIM) instrument on board Solar Orbiter
is capable of performing these measurements. However, the data rate
required to transfer all 4N images with the required cadence is well
beyond the telemetry limit. Here we use realistic, three-dimensional
MHD simulations in order to simulate science data provided by VIM which
are then used to test various compression techniques. We conclude that
lossy data compression and instrumental noise have similar effects on
the output data.

---------------------------------------------------------
Title: S imulations Of Science Data Of The Solo-VIM Instrument
Authors: Yelles, L.; Hirzberger, J.; Lagg, A.; Woch, J.; Solanki,
S. K.; Vögler, A.
2007ESASP.641E..34Y Altcode:
The SolO-VIM instrument will be a two-dimensional full-Stokes
spectro-polarimeter which will provide diffraction-limited
vector-magnetograms, Dopplergrams, and continuum images of the solar
photosphere. The instrument's performance depends on various parameters
such as aperture diameter, filter characteristics, spectral- line
sampling, and orbital position. Here we compute Stokes profiles in
realistic 3D MHD simulations. These synthetic data are then degraded to
match the output ex- pected from the VIM instrument, and subsequently
inverted using a Milne-Eddington atmosphere. We present parameter
studies in order to set up minimum require- ments on limitations of
VIM's capabilities.

---------------------------------------------------------
Title: Velocity distribution of chromospheric downflows
Authors: Aznar Cuadrado, R.; Solanki, S. K.; Lagg, A.
2007msfa.conf..173A Altcode:
Infrared spectropolarimetric observations were obtained with the
Tenerife Infrared Polarimeter (TIP) at the German Vacuum Tower
Telescope (VTT) of the Spanish observatory of Izana, Tenerife. We
present the velocity distributions of a large dataset composed of
maps of the Stokes I, Q, U, and V profiles of active and quiet sun
regions obtained in the chromospheric He I 1083.0 nm triplet. The
line-of-sight velocities were determined by applying a multi-Gaussian
fit to the intensity profiles. Single and double component fits were
carried out for all datasets. We find that 18.7% of all observed
pixels show strong downflows as evidenced by a second line profile
component, generally shifted by more than 8 km s-1 relative to the rest
wavelegth. The distribution of these strong down-flows displays two
distinct populations. The slower one (near sonic and weakly supersonic
flows) has line-of-sight velocities up to 17 km s-1 and is associated
with moderate to strong magnetic signal (up to √(Q2 + U2 + V2)/Ic =
0.08). Strongly supersonic downflows (reaching up to 60 km s-1) are
found at places with weak to moderate magnetic signal, with √(Q2 +
U2 + V2)/Ic values mainly between 0.01 and 0.03.

---------------------------------------------------------
Title: Spectropolarimetry in the chromospheric He I 1083.0 nm
multiplet
Authors: Sasso, C.; Lagg, A.; Solanki, S. K.
2007waas.work...43S Altcode:
Spectropolarimetry in the He I 1083.0 nm multiplet has a great
potential to obtain information on the magnetic field in the solar
upper chromosphere. We apply an inversion technique to infrared
spectropolarimetric observations, to retrieve the full magnetic vector
and the line-of sight velocity. The observations, obtained with the
Tenerife Infrared Polarimeter (TIP) II at the German Vacuum Tower
Telescope (VTT), provide maps in the Stokes parameters I, Q, U and V.

---------------------------------------------------------
Title: Modified p-modes in penumbral filaments
Authors: Bloomfield, D. S.; Lagg, A.; Solanki, S. K.; Borrero, J. M.
2007msfa.conf..241B Altcode:
A time series analysis was performed on velocity signals in a sunspot
penumbra to search for possible wave modes. The spectropolarimetric
photospheric data obtained by the Tenerife Infrared Polarimeter were
inverted using the SPINOR code. An atmospheric model comprising two
magnetic components and one stray-light component gave an optimal fit
to the data. Fourier phase difference analysis between line-of-sight
velocities of both magnetic components provided time delays between
the two atmospheres. These delays were combined with the speeds of
atmospheric wave modes and compared to height separations derived from
velocity response functions to determine the wave mode.

---------------------------------------------------------
Title: Nonlinear Force-Free Magnetic Field Modelling For VIM On SO
Authors: Wiegelmann, T.; Solanki, S. K.; Yelles, L.; Lagg, A.
2007ESASP.641E..19W Altcode:
The aim of this work is to investigate how photon noise and errors
in the retrieval of solar magnetic parameters from measured Stokes
profiles influences the extrapolartion of nonlinear force-free
coronal magnetic fields from photospheric vector magnetograms. To
do so we use a nonlinear force-free extrapolation code based on an
optimization principle. The extrapolation methods has been extensively
tested and applied to data from various telescopes. Here we apply the
code artificial vector magnetograms obtained from 3-D radiation-MHD
simulations. As a reference case we compute the coronal magnetic field
from an ideal magnetogram and compare the result with more realistic
magnetograms based on simulated Solar Orbiter/VIM-measurements. We
investigate the effect of noise, ambiguities, spatial resolution,
inversion mechanism, of Stokes profiles etc. We rate the quality of
the reconstructed coronal magnetic field qualitatively by magnetic
field line plots and quantitatively by a number of comparison metrices,
e.g., the vector correlation with the exact solution and how accurate
the free magnetic energy is computed. Not surprisingly, the instrument
effects and noise influence the quality of the nonlinear force-free
coronal magnetic field model. The extrapolations from realistic vector
magnetograms show a reasonable agreement with the ideal reconstruction,
however, and are in particular significantly better than extrapolations
based on line-of-sight magnetograms only. High quality VIM data
will thus allow reasonably accurate extrapolations that can serve
as the basis for magnetic coupling science through a comparison with
observations from EUS and EUI.

---------------------------------------------------------
Title: Molecular Diagnostics of the Internal Structure of Starspots
and Sunspots
Authors: Afram, N.; Berdyugina, S. V.; Fluri, D. M.; Solanki, S. K.;
Lagg, A.; Petit, P.; Arnaud, J.
2006ASPC..358..375A Altcode:
We have analyzed the usefulness of molecules as a diagnostic tool for
studying solar and stellar magnetism with the molecular Zeeman and
Paschen-Back effects. In the first part we concentrate on molecules
that are observed in sunspots such as MgH and TiO. We present calculated
molecular line profiles obtained by assuming magnetic fields of 2-3 kG
and compare these synthetic Stokes profiles with spectro-polarimetric
observations in sunspots. The good agreement between the theory and
observations allows us to turn our attention in the second part to
starspots to gain insight into their internal structure. We investigate
the temperature range in which the selected molecules can serve as
indicators for magnetic fields on highly active cool stars and compare
synthetic Stokes profiles with our recent observations.

---------------------------------------------------------
Title: Measuring the Magnetic Vector with the He I 10830 Å Line:
A Rich New World
Authors: Solanki, S. K.; Lagg, A.; Aznar Cuadrado, R.; Orozco Suárez,
D.; Collados, M.; Wiegelmann, T.; Woch, J.; Sasso, C.; Krupp, N.
2006ASPC..358..431S Altcode:
The triplet of the He I transitions around 10830 Å not only shows a
rich variety of Stokes profiles, but also allows the full magnetic
vector in the upper chromosphere to be probed, thus revealing
the magnetic structure of loops, current sheets, finely structured
supersonic downflows, the chromospheric layers of sunspots (supporting
the presence of uncombed fields in the penumbra), flares, and the
quiet Sun. A very brief overview of some of the observations and
results obtained so far is given.

---------------------------------------------------------
Title: A New Spoke Formation Model
Authors: Jones, G. H.; Krupp, N.; Krueger, H.; Roussos, E.; Ip, W.;
Mitchell, D. G.; Krimigis, S. M.; Woch, J.; Lagg, A.; Fraenz, M.;
Dougherty, M. K.; Arridge, C. S.; McAndrews, H. J.
2006AGUFM.P34A..06J Altcode:
A new model is proposed for the formation of spokes in Saturn's
rings. We contend that they are formed by the electrostatic charging
of sub-micron ring particles by magnetic field-aligned electron beams
originating in Saturn's atmosphere. The existence of these beams has
recently been confirmed by the MIMI instrument aboard Cassini. Although
observed by MIMI outside the main ring system, the beams are also
expected to occur closer to the planet. On striking the rings, the
electrons charge the dust, causing the levitation of the fine grains
above the main ring plane. A simulation of the proposed formation
process provides strong supporting evidence for the validity of the
process, explaining the spokes' formation locations, morphologies,
and subsequent development as observed in Voyager images. The process
can be tested using Cassini observations; we outline how the model's
validity can be gauged.

---------------------------------------------------------
Title: Icy Moon Absorption Signatures: Probes of Saturnian
Magnetospheric Dynamics and Moon Activity
Authors: Roussos, E.; Krupp, N.; Jones, G. H.; Paranicas, C.; Mitchell,
D. G.; Krimigis, S. M.; Motschmann, U.; Dougherty, M. K.; Lagg, A.;
Woch, J.
2006AGUFM.P51F..03R Altcode:
After the first flybys at the outer planets by the Pioneer and Voyager
probes, it became evident that energetic charged particle absorption
features in the radiation belts are important tracers of magnetospheric
dynamical features and parameters. Absorption signatures are especially
important for characterizing the Saturnian magnetosphere. Due to
the spin and magnetic axes' near-alignment, losses of particles to
the icy moon surfaces and rings are higher compared to the losses at
other planetary magnetospheres. The refilling rate of these absorption
features (termed "micorsignatures") can be associated with particle
diffusion. In addition, as these microsignatures drift with the
properties of the pre-depletion electrons, they provide us direct
information on the drift shell structure in the radiation belts and
the factors that influence their shape. The multiple icy moon L-shell
crossings by the Cassini spacecraft during the first 2 years of the
mission provided us with almost 100 electron absorption events by
eight different moons, at various longitudinal separations from each
one and at various electron energies. Their analysis seems to give a
consistent picture of the electron diffusion source and puts aside a
lot of inconsistencies that resulted from relevant Pioneer and Voyager
studies. The presence of non-axisymmetric particle drift shells even
down to the orbit of Enceladus (3.98 Rs), also revealed through this
analysis, suggests either large ring current disturbances or the
action of global or localized electric fields. Finally, despite these
absorption signatures being observed far from the originating moons,
they can give us hints on the nature of the local interaction between
each moon and the magnetospheric plasma. It is, nevertheless, beyond
any doubt that energetic charged particle absorption signatures are a
very powerful tool that can be used to effectively probe a series of
dynamical processes in the Saturnian magnetosphere.

---------------------------------------------------------
Title: Supersonic Downflows in the Vicinity of a Solar Pore
Authors: Lagg, A.; Woch, J.; Solanki, S. K.; Gandorfer, A.
2006ASPC..358..437L Altcode:
At the footpoints of magnetic arcades spanning over a site of flux
emergence we observe strong redshifts in the He I triplet at 1083
nm. These redshifts are associated with downflow speeds of up to
40 km s-1. Within the spatial resolution of our data (1
arcsec-2 arcsec) obtained with the Tenerife Infrared Polarimeter at
the VTT we find an almost unshifted atmospheric component coexisting
with the redshifted component. We were able to retrieve the magnetic
field configuration in both the unshifted and the redshifted component
simultaneously and infer an uncombed, fibril-like structure of the
upper chromosphere. The supersonic downflow speeds are interpreted as
a consequence of a significantly reduced pressure scale height above
the pore, where the magnetic arcades are rooted. A temporal series of
the fast downflow region reveals that the supersonic flow is maintained
for more than one hour. Making use of the increased spatial resolution
of the new TIP2 instrument we are working on reducing the upper limit
on the size of the fibril-like flux channels in the upper chromosphere.

---------------------------------------------------------
Title: Formation of Saturn's ring spokes by lightning-induced
electron beams
Authors: Jones, G. H.; Krupp, N.; Krüger, H.; Roussos, E.; Ip,
W. -H.; Mitchell, D. G.; Krimigis, S. M.; Woch, J.; Lagg, A.; Fränz,
M.; Dougherty, M. K.; Arridge, C. S.; McAndrews, H. J.
2006GeoRL..3321202J Altcode:
Spokes are near-linear markings sometimes visible on Saturn's
rings. They are widely accepted as being electrostatically-levitated
sheets of ~0.6 micron-radius charged grains. Previously-suggested causes
of the grains' charging do not agree with all spoke characteristics,
which include their rapid generation, localized formation primarily in
Saturn's midnight-dawn sector, the seasonality of their apparitions,
and, crucially, their morphologies. We contend that spokes are caused
by lightning-induced electron beams striking the rings, at locations
magnetically-connected to thunderstorms. This view is supported by
a semi-quantitative spoke morphology simulation. Spokes' formation
locations are further controlled by Saturn's ionospheric density,
which reaches a near-dawn minimum where electron beams can most easily
propagate to the rings. The beams may generate observed X-ray emission,
supply particles to Saturn's radiation belts, and over time will modify
the rings' constituents. Finally, we report Cassini MIMI instrument
observations of an electron burst which displays some characteristics
expected of a lightning-induced event.

---------------------------------------------------------
Title: Correction to “Ion abundance ratios in the Jovian
magnetosphere”
Authors: Radioti, A.; Krupp, N.; Woch, J.; Lagg, A.; Glassmeier,
K. -H.; Waldrop, L. S.
2006JGRA..11110224R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: A New Spoke Formation Model
Authors: Jones, Geraint H.; Krupp, N.; Krueger, H.; Roussos, E.; Ip,
W.; Mitchell, D. G.; Krimigis, S. M.; Woch, J.; Lagg, A.; Fraenz,
M.; Dougherty, M. K.; Arridge, C. S.; McAndrews, H. J.
2006DPS....38.4214J Altcode: 2006BAAS...38..562J
We propose a new model for the formation of spokes in Saturn's
rings. The model involves the electrostatic charging of sub-micron
dust grains in the rings by magnetic field-aligned electron beams. Such
beams have recently been observed by the MIMI instrument aboard Cassini
at 3.1 Saturn radii, outside the main ring system. It is reasonable to
expect the beams to also occur closer to the planet. We contend that on
striking the rings, the electron beams’ dust-charging effects cause
the levitation of the fine grains above the main ring plane, forming
the spokes. Using a semi-quantitative model, we explain the spokes’
formation locations, their initial morphologies, and the subsequent
development of their appearance as reported in studies based on Voyager
observations. Controlling effects on the spokes’ locations are
also proposed. We outline tests that can be carried out using Cassini
datasets to gauge the validity of our proposed formation process. MIMI/LEMMS work at MPS is financed by the German Bundesministerium
für Bildung und Forschung, and by the Max Planck Gesellschaft.

---------------------------------------------------------
Title: Milne-Eddington inversions of the He &lt;sf&gt;I&lt;/sf&gt;
10 830 Å Stokes profiles: influence of the Paschen-Back effect
Authors: Sasso, C.; Lagg, A.; Solanki, S. K.
2006A&A...456..367S Altcode: 2011arXiv1102.0898S
Context: .The Paschen-Back effect influences the Zeeman sublevels
of the He I multiplet at 10 830 Å, leading to changes in strength
and in position of the Zeeman components of these lines. Aims:
.We illustrate the relevance of this effect using synthetic Stokes
profiles of the He I 10 830 Å multiplet lines and investigate its
influence on the inversion of polarimetric data. Methods: .We
invert data obtained with the Tenerife Infrared Polarimeter (TIP)
at the German Vacuum Tower Telescope (VTT). We compare the results of
inversions based on synthetic profiles calculated with and without the
Paschen-Back effect being included. Results: .We find that when
taking into account the incomplete Paschen-Back effect, on average 16%
higher field strength values are obtained. We also show that this effect
is not the main cause for the area asymmetry exhibited by many He I
10 830 Stokes V-profiles. This points to the importance of velocity
and magnetic field gradients over the formation height range of these
lines.

---------------------------------------------------------
Title: Multi-component analysis of a flaring region in the
chromospheric He I 1083.0 nm triplet
Authors: Sasso, C.; Lagg, A.; Solanki, S. K.
2006IAUJD...3E..31S Altcode:
We present infrared spectropolarimetric observations of the solar active
region NOAA 0763 obtained with the new Tenerife Infrared Polarimeter
(TIP 2) at the German Vacuum Tower Telescope (VTT) during May 2005,
taken in the chromospheric He I 1083.0 nm multiplet. The region was
in the initial phase of a C2.0 flare. We observe up to 4 atmospheric
components within the spatial resolution of our observations. The
components are clearly separated in wavelength, the largest separation
corresponding to downflow velocities of up to 64 km/s. We give
preliminary results on the magnetic vector and the line-of sight
velocity obtained by inverting the Stokes I, Q, U and V profiles of
the He 1083.0 nm triplet.

---------------------------------------------------------
Title: Flux Emergence In The Solar Photosphere - Diagnostics Based
On 3-D Rradiation-MHD Simulations
Authors: Yelles Chaouche, L.; Cheung, M.; Lagg, A.; Solanki, S.
2006IAUJD...3E..75Y Altcode:
We investigate flux tube emergence in the solar photosphere using a
diagnostic procedure based on analyzing Stokes signals from different
spectral lines calculated in 3-D radiation-MHD simulations. The
simulations include the effects of radiative transport and partial
ionization and cover layers both above and below the solar surface. The
simulations consider the emergence of a twisted magnetic flux tube
through the solar surface. We consider different stages in the emergence
process, starting from the early appearance of the flux tube at the
solar surface, and following the emergence process until the emerged
flux looks similar to a normal bipolar region. At every stage we compute
line profiles by numerically solving the Unno-Rachkovsky equations at
every horizontal grid point. Then, following observational practice,
we apply Milne-Eddington-type inversions to the synthetic spectra in
order to retrieve different atmospheric parameters. We include the
influence of spatial smearing on the deduced atmospheric parameters
to identify signatures of different stages of flux emergence in the
solar photosphere.

---------------------------------------------------------
Title: Solar Coronal Magnetic Field Mapper
Authors: Solanki, S. K.; Raouafi, N. -E.; Gandorfer, A.; Schühle,
U.; Lagg, A.
2006ESASP.617E.160S Altcode: 2006soho...17E.160S
No abstract at ADS

---------------------------------------------------------
Title: Planetary Rotation Modulation of Various Measured Plasma
Parameters in Saturns Magnetosphere: a Possible Mechanism
Authors: Mitchell, D. G.; Brandt, P. C.; Carbary, J. F.; Krimigis,
S. M.; Mauk, B. E.; Paranicas, C. P.; Roelof, E. C.; Jones, G.;
Krupp, N.; Lagg, A.; Gurnett, D. A.; Kurth, W. S.; Dougherty, M. K.;
Southwood, D. J.; Saur, J.; Zarka, P.
2006AGUSM.P44A..04M Altcode:
The period of Saturn kilometric radiation (SKR) modulation established
by Voyagers 1 and 2 in 1980 and 1981 (10 hours, 39 minutes, 22.4 +/-
7s) has been adopted by the International Astronomical Union as the
official rotation period of Saturn. Other quantities seen to exhibit
modulation at about the same period include the magnetic field,
energetic electron spectral slope, and energetic neutral atom (ENA)
emission. However first the Ulysses spacecraft, and later Cassini, have
measured a significantly different the SKR period than the Voyagers
(approximately 10 hours, 45minutes). This change is problematic,
because if the field is truly locked to Saturns rotation, this would
imply a huge change in angular momentum over a relatively short
period. Furthermore, no consensus model has been accepted to explain
how the effects of the rotation are communicated from the planetary body
out to distances as large as over 20 Rs (Saturn radii). In this paper,
we explore the possibility that the observed SKR period is not Saturns
intrinsic rotation period, but rather stems from friction between
the ionosphere and Saturns zonal wind flows. We suggest that the SKR
location reflects a high conductivity anomaly in Saturns ionosphere,
whereby rigid rotation is imposed on that part of the magnetosphere
that connects via the magnetic field and field-aligned currents with
this high conductivity anomaly (this is similar to the hypothesis of
the camshaft model for the magnetic perturbation suggested by Espinosa
et al., 2003). In that work, Espinosa et al. suggest that the high
conductivity region exists because of a high order magnetic anomaly,
that affects ionospheric conductivity locally. We extend that model
to include a feed-back loop with the magnetosphere. In this scenario,
a magnetospheric disturbance initially triggered by interaction with
the field-aligned currents results in additional energy deposition in
the ionosphere. This further increases the ionospheric conductivity,
but more importantly ties the high conductivity region to the middle
magnetospheric disturbance. The local zonal thermospheric winds,
if they are in frictional equilibrium with the conducting ionosphere,
will move the high conductivity region (and the rest of the ionosphere)
at whatever velocity they are traveling. With the feedback between the
magnetospheric heating and the ionospheric conductivity established, the
field-aligned current remains rooted in the wind-convected ionosphere,
and so the active (SKR) meridian will slowly drift away from the
core-rooted magnetic anomaly. The process will be self-sustaining
for a certain length of time, until it fizzles out (either because
the magnetospheric instability is no longer sufficiently close to
triggering, or because the source particle populations are depleted,
or whatever). Some time later, when the magnetosphere has stored
sufficient energy to prime the instability, it will go off again,
again starting at the location of the magnetic anomaly. Espinosa,
S. A., D. J. Southwood, and M. K. Dougherty, How can Saturn impose its
rotation period in a noncorotating magnetosphere? J. Geophys. Res.,
108(A2), 1086, doi:10.1029/2001JA005084, 2003

---------------------------------------------------------
Title: On the fine structure of sunspot penumbrae. III. The vertical
extension of penumbral filaments
Authors: Borrero, J. M.; Solanki, S. K.; Lagg, A.; Socas-Navarro,
H.; Lites, B.
2006A&A...450..383B Altcode: 2005astro.ph.10586B
In this paper we study the fine structure of the penumbra as inferred
from the uncombed model (flux tube embedded in a magnetic surrounding)
when applied to penumbral spectropolarimetric data from the neutral
iron lines at 6300 Å. The inversion infers very similar radial
dependences in the physical quantities (LOS velocity, magnetic field
strength etc.) as those obtained from the inversion of the Fe I 1.56
μm lines. In addition, the large Stokes V area asymmetry exhibited
by the visible lines helps to constrain the size of the penumbral
flux tubes. As we demonstrate here, the uncombed model is able to
reproduce the area asymmetry with striking accuracy, returning flux
tubes as thick as 100-300 kilometers in the vertical direction, in
good agreement with previous investigations.

---------------------------------------------------------
Title: Enceladus' Varying Imprint on the Magnetosphere of Saturn
Authors: Jones, G. H.; Roussos, E.; Krupp, N.; Paranicas, C.; Woch,
J.; Lagg, A.; Mitchell, D. G.; Krimigis, S. M.; Dougherty, M. K.
2006Sci...311.1412J Altcode:
The bombardment of Saturn's moon Enceladus by &gt;20-kiloelectron volt
magnetospheric particles causes particle flux depletions in regions
magnetically connected to its orbit. Irrespective of magnetospheric
activity, proton depletions are persistent, whereas electron depletions
are quickly erased by magnetospheric processes. Observations of these
signatures by Cassini's Magnetospheric Imaging Instrument allow remote
monitoring of Enceladus' gas and dust environments. This reveals
substantial outgassing variability at the moon and suggests increased
dust concentrations at its Lagrange points. The characteristics of
the particle depletions additionally provide key radial diffusion
coefficients for energetic electrons and an independent measure of
the inner magnetosphere's rotation velocity.

---------------------------------------------------------
Title: Anti-planetward auroral electron beams at Saturn
Authors: Saur, J.; Mauk, B. H.; Mitchell, D. G.; Krupp, N.; Khurana,
K. K.; Livi, S.; Krimigis, S. M.; Newell, P. T.; Williams, D. J.;
Brandt, P. C.; Lagg, A.; Roussos, E.; Dougherty, M. K.
2006Natur.439..699S Altcode:
Strong discrete aurorae on Earth are excited by electrons, which are
accelerated along magnetic field lines towards the planet. Surprisingly,
electrons accelerated in the opposite direction have been recently
observed. The mechanisms and significance of this anti-earthward
acceleration are highly uncertain because only earthward acceleration
was traditionally considered, and observations remain limited. It
is also unclear whether upward acceleration of the electrons is a
necessary part of the auroral process or simply a special feature
of Earth's complex space environment. Here we report anti-planetward
acceleration of electron beams in Saturn's magnetosphere along field
lines that statistically map into regions of aurora. The energy spectrum
of these beams is qualitatively similar to the ones observed at Earth,
and the energy fluxes in the observed beams are comparable with the
energies required to excite Saturn's aurora. These beams, along with
the observations at Earth and the barely understood electron beams in
Jupiter's magnetosphere, demonstrate that anti-planetward acceleration
is a universal feature of aurorae. The energy contained in the beams
shows that upward acceleration is an essential part of the overall
auroral process.

---------------------------------------------------------
Title: Icy moon absorption signatures reveal non-axisymmetric
drift shells in the Saturnian radiation belts: implications for a
magnetospheric electric field?
Authors: Roussos, E.; Krupp, N.; Jones, G. H.; Paranicas, C.; Lagg,
A.; Woch, J.; Mitchell, D. G.; Krimigis, S. M.; Dougherty, M. K.
2006epsc.conf..545R Altcode:
Data collected during the first 22 orbits of Cassini by the MIMI/LEMMS
experiment revealed a significant number of energetic electron
absorption features (microsignatures) from the icy moons Enceladus,
Tethys and Dione, between 3.8 and 7 Rs . As the absorption regions
drift as the pre-depletion plasma, electron microsignatures can be
used as drift-shell tracers. By organizing the observed location of the
microsignatures with local time we find that electrons have the tendency
to drift inward in the midnight section and outward in the noon to dusk
sector. Displacements up to 0.5 Rs at Tethys and 0.9 Rs at Dione cannot
only be the result of magnetopause and ring current disturbances. This
suggests the presence of an electric field or other processes that
cause significant deviations from drift shell axisymmetry, even down
to 5 Rs . We investigate possible mechanisms that could account for
these observations (such the possible influence of a dusk to dawn
electric field). Irrespective of the mechanism responsible for the
observed displacements, the non-axisymmetric drift shells could be in
part responsible for plasma transport inside the L-shells of Dione and
Tethys as the refilling of the electron microsignatures points to very
slow radial diffusion for electrons.

---------------------------------------------------------
Title: The Saturnian magnetosphere after two years of Cassini in
situ results
Authors: Krupp, N.; Jones, G. H.; Roussos, E.; Lagg, A.; Mitchell,
D. G.; Krimigis, S. M.; Arridge, C.; McAndrews, H.; Dougherty, M. K.;
Kurth, W.
2006epsc.conf..386K Altcode:
The Cassini spacecraft arrived at Saturn in July 2004. Since then the
particles and fields instrument onboard have continuously monitoring the
Saturnian magnetosphere for more than 30 orbits covering mostly the dawn
and predawn regions. In this study we use energetic particle, magnetic
field and plasma wave data obtained during the first two years in orbit
to investigate the global structure of the Saturnian magnetosphere
and its dynamics. On a global scale the Cassini data reveal a variety
of spatial structures in the inner and outer magnetosphere as well as
temporal variations in most of the derived properties. We will show
local time, latitude and longitude variations of energetic particles
and changes in the energy spectrum as well as correlations with other
data sets. Highest intensities of energetic particles have been found
in the radiation belts between 6 and 15 RS with a local time asymmetry
between dawn and dusk. The outer magnetosphere beyond that distance
sometimes show very pronounced dropouts in the magnetotail indicating
dynamical processes in that part of the magnetosphere. Parameters
from the plasma, magnetic field and plasma wave investigations show
also an unexpected modulation at the planetary rotation period. The
investigation of these modulations is key to understanding the dynamics
of the Saturnian magnetosphere and will be discussed in the talk.

---------------------------------------------------------
Title: Influence of the Paschen-Back effect on the results of
polarimetric inversions of the He I 10830 Å triplet
Authors: Sasso, C.; Lagg, A.; Solanki, S. K.; Socas-Navarro, H.
2006MSAIS...9..126S Altcode:
The He I triplet at 10830 Å has a great potential for determining the
magnetic field vector in the upper chromosphere. The triplet is Zeeman
sensitive (Landé factors 2.0, 1.75 and 1.25) and shows the signature of
the Hanle effect under appropriate conditions. Additionally, the Zeeman
sublevels are influenced by the Paschen-Back effect leading to changes
in strength and in position of the Zeeman components of the transitions
forming the triplet. In this work we calculate the influence of the
Paschen-Back effect on the Stokes profiles and investigate its relevance
to inversions on spectro-polarimetric data obtained with the Tenerife
Infrared Polarimeter (TIP) at the German Vacuum Tower Telescope (VTT).

---------------------------------------------------------
Title: Comparison periodic substorms at Jupiter and Earth
Authors: Kronberg, E. A.; Woch, J.; Krupp, N.; Lagg, A.; Glassmeier,
K. -H.
2006epsc.conf..483K Altcode:
The Energetic Particles Detector and magnetometer measurements on
Galileo showed that the Jovian magnetosphere undergoes reconfiguration
processes which are very similar to the characteristics of a
terrestrial substorm. At Jupiter the reconfiguration process occurs
quasi-periodically with a repetition period of several days. In the
terrestrial magnetosphere periodic substorms have been occasionally
observed. The comparison of these periodic magnetospheric disturbances
shows that they are similar in spatial distribution as well as in
dynamic features, in spite of that the energy sources are different. In
the case of the Earth, the well established energy source is the solar
wind. In the case of the Jovian magnetosphere, it is the internal
energy supplied by mass loading of fast rotating flux tubes. The energy
accumulation and release leads to similar features: in the particle
data we observed periodic "sawtooth" intensity fluctuations and plasma
pressure and bulk velocity variations. In the magnetic field reoccurring
signatures of stretching and dipolarization are observed. Furthermore,
the release process is associated with an intensification of auroral
emissions. In both magnetospheres signatures of cross-tail and
field-aligned current generations are found.

---------------------------------------------------------
Title: The interaction of Rhea with Saturn's magnetosphere
Authors: Jones, G. H.; Roussos, E.; Krupp, N.; Lagg, A.; Woch, J.;
Cassini MIMI Team
2006epsc.conf..382J Altcode:
Rhea, a 1500km-wide icy satellite of Saturn, orbits the planet at
8.7 Saturn radii. The Cassini spacecraft's single close approach
to the moon to date occurred on November 26, 2005, approaching to
within 500km of Rhea's surface. The LEMMS sensors of Cassini's MIMI
instrument observed energetic (&gt;20keV) electrons and ions in the
moon's vicinity. As expected, a significant depletion was observed
in low energy electrons downstream of the moon in the magnetospheric
corotation flow. This missing population constituted particles that
struck Rhea, forming a wake downstream. In addition to this relatively
well-understood feature, the LEMMS data revealed a wide, relatively
shallow electron flux depletion extending for several Rhea radii both
inbound and outbound. Energetic ions also changed their characteristics
within this broad region - a volume of space much larger than expected
for a magnetospheric interaction with an inert body. We present our
interpretation of this perplexing interaction region.

---------------------------------------------------------
Title: Comparison of the mass-release processes at Jupiter and Earth.
Authors: Kronberg, E. A.; Woch, J.; Krupp, N.; Lagg, A.; Glassmeier,
K. -H.
2006cosp...36.1712K Altcode: 2006cosp.meet.1712K
The study using Energetic Particles Detector and magnetometer
measurements on Galileo discovered that the corotational flow inherent
for the Jovian magnetosphere is disrupted by radially outward and
inward particle bursts in the magnetotail These bursts are associated
with transient bipolar south-north magnetic field distortions and
were reffered to the reconfiguration events at Jupiter and they are
very similar to terrestrial substorms in terms of the characteristic
features The reconfiguration process in the magnetotail consists
of a transition from a quiet loading state to a disturbed state In
analogy with the terrestrial substorm process the initial loading
phase resembles characteristics of the growth loading phase and the
disturbed phase unloading resembles the expansion phase of terrestrial
substorms The recovery phase of the Jovian reconfiguration process
seems to be very short in relation to the other phases similar as in
the terrestrial case A closer look at the substorm-like processes in
the Jovian magnetosphere also reveals further features similar to the
terrestrial substorms such as the onset of magnetic fluctuations on a
time scale of an ion gyroperiod in the magnetotail plasma sheet boundary
layer formation signatures of travelling compression regions and the
formation of a post plasmoid plasma sheet The signatures of cross-tail
and field-aligned current generations during the reconfiguration
process e g potential drop reversed dispersion of ions and electrons
timing of reconfiguration events support the substorm

---------------------------------------------------------
Title: Particles and fields in Saturn's magnetosphere: Cassini
results after 2 years in orbit
Authors: Krupp, N.; Jones, G. H.; Roussos, E.; Lagg, A.; Woch, J.;
Mitchell, D. G.; Krimigis, S. M.; Arridge, C.; McAndrews, H.; Kurth, W.
2006cosp...36.2071K Altcode: 2006cosp.meet.2071K
The Cassini spacecraft arrived at Saturn in July 2004 Since then the
particles and fields instrument onboard have continuously monitoring
the Kronian magnetosphere for more than 30 orbits In this study we use
energetic particle and magnetic field data obtained during the first
two years in orbit to investigate the global structure of the Saturnian
magnetosphere and its dynamics On a global scale the Cassini data reveal
a variety of spatial structures and temporal variations in Saturn s
magnetosphere We will show local time latitude and longitude variations
of energetic particles fluxes and changes in the energy spectrum as
well as correlations with other instruments Highest intensities of
energetic particles have been found between 6 and 15 RS with a local
time asymmetry between dawn and dusk Parameters from the plasma magnetic
field and plasma wave investigations show a very pronounced modulation
at the planetary rotation period The investigation of these modulations
is key to understanding the dynamics of the Saturnian magnetosphere

---------------------------------------------------------
Title: Energetic particle composition during substorm-like events
in the Jovian magnetosphere
Authors: Radioti, A.; Woch, J.; Kronberg, E.; Krupp, N.; Glassmeier,
K. -H.; Lagg, A.
2006cosp...36..660R Altcode: 2006cosp.meet..660R
Based on the first 15 orbits of the Galileo spacecraft the composition
of the energetic ion population of the Jovian magnetosphere is studied
on a global scale Analyzing data from the Energetic Particles Detector
onboard Galileo we study the relative ion abundance ratios of S O S
He O He and p He at various energy nucleon Prominent enhancements
of S O S He and O He abundance ratios are observed in the predawn
sector associated with substorm-like events in the magnetotail During
these reconfiguration events frequent small-scale variations of the
south-north component of the magnetic field are present Acceleration
by such magnetic field variations is examined as a possible mechanism
for particle energization in that region When the time scale of the
magnetic field variation is comparable to the particle gyro period the
particle is accelerated by the induced electric field It is shown that
during the Jovian substorms sulfur and oxygen ions are more effectively
energized than helium and protons generating the observed ion abundances

---------------------------------------------------------
Title: Magnetic field measurements at different levels in the solar
atmosphere and magnetic coupling
Authors: Solanki, S. K.; Lagg, A.
2006cosp...36..916S Altcode: 2006cosp.meet..916S
The magnetic field couples the different layers of the solar atmosphere
with each other To unravel this coupling we need to be able to
measure the field at all the relevant levels Most measurements of
the magnetic field refer to the photosphere where magnetographs
and spectropolarimetry using the Zeeman effect have allowed the
magnetic structure and its evolution to be studied Observations of
the field at higher layers in the atmosphere are more rare although
a number of techniques are available These include Zeeman-effect and
Hanle effect based measurements in the chromosphere and the corona
as well as radio observations of coronal magnetic field These direct
measurements are complemented by magnetic field extrapolations starting
from the photosphere A brief overview of results obtained by various
techniques of magnetic field measurements is given and a more detailed
discussion of the main results of recent measurements of the field in
the photosphere and the upper chromosphere are presented

---------------------------------------------------------
Title: The magnetospheric dynamics: Periodic substorms and Jupiter
and Earth
Authors: Kronberg, E. A.; Woch, J.; Glassmeier, K. -H.; Krupp, N.;
Lagg, A.
2006cosp...36.1715K Altcode: 2006cosp.meet.1715K
The Jovian and terrestrial magnetospheres show both fundamental
commonalities and differences in their dynamical behaviour The Jovian
substorm-like process is different from the terrestrial one by the
inherently periodic behavior The cycle of topological stretching
dipolarization repeats every several days Storage of magnetic energy in
the lobe region by interaction with the interplanetary medium seems not
to be the prime driver of the reconfiguration process Rather the Jovian
reconfiguration process is internally driven In order to confirm this
a simple conceptual model for this periodic process was developed It
assumes that the ion-mass loading from internal plasma sources and the
fast planetary rotation causes magnetotail field line stretching due
to centrifugal forces This leads to the development of a magnetotail
configuration favoring magnetic reconnection It is established that
the condition for the onset of a tearing mode instability is satisfied
just before each disturbed period of the reconfiguration process This
causes both plasmoid formation and their release with continuing mass
loading leading to renewed stretching of tail field lines The model
yields that the intrinsic time constant of the Jovian reconfiguration
process depends primarily on internal parameters like the mass-loading
rate and is affected by the external solar wind conditions This model
shows that the suggested intrinsic mechanism can explain the observed
periodicities of several days of the Jovian substorm-like process We
compare the Jovian periodical mass release processes

---------------------------------------------------------
Title: New insights into chromospheric structures from vector magnetic
field measurements
Authors: Lagg, A.
2006cosp...36..549L Altcode: 2006cosp.meet..549L
During the last decade advances in instrumentation atomic physics
and modeling have greatly improved the access to the chromospheric
magnetic field vector High sensitivity polarimeters like the Tenerife
Infrared Polarimeter TIP2 VTT or the Spectro-Polarimeter for Infrared
and Optical Regions SPINOR HAO lead to reliable Zeeman measurements
using the He I 10830 nm triplet Theoretical modeling of the Hanle and
the Paschen Back effect helped to significantly improve the analysis
of polarization measurements in this triplet allowing to directly
visualize the magnetic structure of spicules polar prominences and
active regions In this presentation I will summarize the results of
chromospheric magnetic field measurements using this interesting triplet
obtained in the last couple of years and discuss the great potential
it has to further uncover the complex structure of the chromosphere

---------------------------------------------------------
Title: Temporal variability of the ion abundance ratios in the
Jovian magnetosphere
Authors: Radioti, A.; Krupp, N.; Woch, J.; Lagg, A.; Glassmeier, K. -H.
2006cosp...36..661R Altcode: 2006cosp.meet..661R
Galileo as the first orbiting spacecraft around Jupiter provides the
opportunity to study globally and in an extended energy range the
energetic particle composition of the Jovian magnetosphere Analyzing
data from the Energetic Particles Detector onboard Galileo we study the
relative ion abundance ratios of S O S He O He and p He at various
energy nucleon The global coverage of the Galileo trajectories
enables a quantitative comparison with results of previous missions
and especially Voyager 2 for the same radial distance and local time
The large discrepancies found are attributed to a strong energy
dependence but also to secular variations Ion intensities exhibit
strong time variations between the two missions Temporal variations do
exist also on times scales of several weeks as shown by the analysis
of consecutive Galileo orbits Large and small scale variations of the
ion abundance ratios are related to the temporal variability of the
Io torus and to solar wind changes Additionally time varying particle
acceleration processes are discussed

---------------------------------------------------------
Title: Low energy electron microsignatures at the orbit of Tethys:
Cassini MIMI/LEMMS observations
Authors: Roussos, E.; Krupp, N.; Woch, J.; Lagg, A.; Jones, G. H.;
Paranicas, C.; Mitchell, D. G.; Livi, S.; Krimigis, S. M.; Dougherty,
M. K.; Armstrong, T.; Ip, W. -H.; Motschmann, U.
2005GeoRL..3224107R Altcode:
We report on low energy electron microsignature observations by the
Low Energy Magnetospheric Measurement System (LEMMS) in the vicinity
of Tethys's L-shell, during the first seven orbits of the Cassini
mission. Tethys, due to its large size, is the source of strong
microsignatures. Shallower absorption features seen are the result
of aged Tethys microsignatures rather than the effect of its small
Lagrangian moons. Several remarkable observations are also discussed:
the displacement of the microsignatures indicates that the drift shell
deviation from axisymmetry is greater than previously expected. Midnight
to dawn wakes have drifted toward the planet whereas noon to dusk ones
have drifted outward, revealing possible magnetospheric convection
effects. Double microsignatures seen for the first time, suggest
low radial diffusion coefficients and point to dynamic events in the
magnetosphere.

---------------------------------------------------------
Title: Electron microsignatures from the Saturnian satellites:
Cassini MIMI/LEMMS observations
Authors: Roussos, E.; Krupp, N.; Jones, G. H.; Lagg, A.; Woch, J.;
Paranicas, C.; Mitchell, D. G.; Krimigis, S. M.; Dougherty, M. K.;
Ip, W. H.; Armstrong, T. P.
2005AGUFM.P43A0955R Altcode:
Since the Saturn Orbit Insertion in July 2004, Cassini has performed
numerous crossings of Saturn's inner moons L-shells at various
longitudinal distances from the moons. The Low Energy Magnetospheric
Measurement System (LEMMS) has detected a significant number of
absorption features, referred to as microsignatures, in the the lowest
energy electron channels (20-200 keV). The detections occur mainly
in the vicinity of Tethys and Dione L-shells, while microsignatures
from Enceladus, Rhea and Mimas are less frequent. From the analysis
of these features we present: (i) estimates of the radial diffusion
coefficient in Saturn's radiation belts as a function of L and
energy, including for the first time their dependence on local time,
(ii) the region of influence that the electric fields and energetic
events (e.g. injections) have on the electron drift shells and (iii)
the implications for the unique interaction characteristics of each
moon with Saturn's magnetospheric plasma. Data from the recent close
flybys of Tethys, Dione and Rhea are also briefly discussed.

---------------------------------------------------------
Title: Global Structure and Dynamics of the Kronian Magnetosphere:
Cassini Results
Authors: Krupp, N.; Lagg, A.; Woch, J.; Jones, G. H.; Roussos, E.;
Krimigis, S. M.; Livi, S.; Mitchell, D. G.; Roelof, E. C.; Paranicas,
C.; Hamilton, D. C.; Armstrong, T. P.; Dougherty, M. K.
2005AGUFM.P43A0949K Altcode:
Since July 2004 the Cassini spacecraft is in orbit around Saturn
providing in-situ measurements of the Saturnian magnetosphere. Several
magnetospheric regions could be identified including the intense
radiation belts and ring current regions in the inner magnetosphere as
well as the equatorial plasma sheet and the regions close to the outer
boundaries of the magnetosphere from which the global structure as well
as the dynamic of the Kronian magnetosphere can be studied. Using the
energetic particle measurements from the MIMI instrument as well as the
magnetic field measurements from the MAG instrument onboard Cassini
we will discuss the derived pitch angle distributions, electron and
ion energy spectra and periodicities in magnetic field components and
particle parameters in various regions. Some of the results are (1)
asymmetry in the particle fluxes between the day and night sector
at comparable distances; (2) highly varying particle fluxes as a
consequence of large-scale dynamic processes in the equatorial plasma
sheet; (3) field-aligned bi-directional electron fluxes in the outer
part of the Kronian magnetosphere with correlation to the Saturnian
aurora; (4) variations of the magnetic field components and electron
fluxes with the planetary rotation period pointing to a magnetic
anomaly inside the planet or pointing to corotating structures in the
Saturnian magnetotail; (5) injections and corotating structures in
Saturn's magnetotail as a consequence of dynamical processes.

---------------------------------------------------------
Title: Macrosignatures of the icy moons in the inner magnetosphere
of Saturn
Authors: Jones, G. H.; Roussos, E.; Krupp, N.; Woch, J.; Lagg, A.;
Paranicas, C.; Krimigis, S. M.; Mitchell, D. G.; Mauk, B. H.; Ip,
W. -P.; Dougherty, M. K.
2005AGUFM.P43A0958J Altcode:
The energetic particle population of the inner magnetosphere of
Saturn is significantly affected by the presence of the planet's icy
moons. Charged particles that strike the surfaces of these moons are
removed from the magnetosphere, significantly reducing the fluxes of
particles observed on crossing these moons' L-shells. The signatures
have previously been separated into two classes: Microsignatures
are temporary signatures in longitude and time observed in the
charged-particle wakes of satellites. Macrosignatures are longitude-
and time-averaged effects of absorbers on the radial distribution of
particles. Here, we present an overview of the decreases in energetic
particle fluxes observed at these moons' L-shells, as observed by the
LEMMS portion of the MIMI instrument aboard Cassini. We concentrate
on macrosignatures, particularly those at the L-shell of Enceladus,
where a deep, persistent decrease in energetic protons is observed. We
discuss these features' formation, and the possible contribution of
E-ring material to the observed flux decreases. It has recently been
suggested that charged particle bombardment leads to a conversion of
water ice from a crystalline to an amorphous state. Here we discuss
the particle evidence for persistent weathering of Enceladus's surface
and the extent to which each charged species is likely involved in
this process.

---------------------------------------------------------
Title: Observation of the Spectrum and Angular Distribution of Trapped
Protons in Saturn's Inner Magnetosphere: Implications for Sources,
Transport, and Loss
Authors: Armstrong, T.; Manweiler, J.; Krupp, N.; Lagg, A.; Krimigis,
S.; Livi, S.; Mitchell, D.; Roelof, E.; Paranicas, C.; Hamilton, D.
2005AGUFM.P43A0951A Altcode:
The Cassini MIMI investigation carried a set of solid state detectors
designed in part to resolve the shape and magnitude a local minimum
in the flux of energetic protons at about 10 MeV reported from the
Voyager 2 flyby in 1981. Preliminary results from Cassini Saturn
Orbit Injection (SOI) show that this reported feature of the proton
spectrum has persisted throughout the region within Dione's orbit . We
will report the fluxes, pitch angle distributions, and phase space
densities along with our estimates of source and loss processes of
Saturnian trapped protons. Further, we will attempt to reconcile our
results with those from Voyagers 1 and 2 and Pioneer 11, especially
regarding the inner "CRAND" source.

---------------------------------------------------------
Title: Diagnostics of a Simulated Flux Tube Emergence
Authors: Yelles Chaouche, L.; Cheung, M.; Lagg, A.; Solanki, S.
2005ESASP.600E..74Y Altcode: 2005ESASP.600E..74C; 2005ESPM...11...74C; 2005dysu.confE..74C
No abstract at ADS

---------------------------------------------------------
Title: Influence of the Paschen-Back Effect on the Stokes Profiles
of the he 10830 Å Triplet
Authors: Sasso, C.; Lagg, A.; Solanki, S. K.
2005ESASP.596E..64S Altcode: 2005ccmf.confE..64S
No abstract at ADS

---------------------------------------------------------
Title: Results from Chromospheric Magnetic Field Measurements
Authors: Lagg, A.
2005ESASP.596E...6L Altcode: 2005ccmf.confE...6L
No abstract at ADS

---------------------------------------------------------
Title: International Scientific Conference on Chromospheric and
Coronal Magnetic Fields
Authors: Innes, D. E.; Lagg, A.; Solanki, S. A.
2005ESASP.596E....I Altcode: 2005ccmf.confE....I
No abstract at ADS

---------------------------------------------------------
Title: Photospheric and Chromospheric Magnetic Structure of a Sunspot
Authors: Orozco Suarez, D.; Lagg, A.; Solanki, S. K.
2005ESASP.596E..59O Altcode: 2005ccmf.confE..59O
No abstract at ADS

---------------------------------------------------------
Title: Magnetic Loops: a Comparison of Extrapolations from the
Photosphere with Chromospheric Measurements
Authors: Wiegelmann, T.; Lagg, A.; Solanki, S.; Inhester, B.; Woch, J.
2005ESASP.596E...7W Altcode: 2005ccmf.confE...7W
No abstract at ADS

---------------------------------------------------------
Title: International Scientific Conference on Chromospheric and
Coronal Magnetic Fields
Authors: Innes, D. E.; Lagg, A.; Solanki, S. A.
2005ESASP.596.....I Altcode: 2005ccmf.conf.....I
No abstract at ADS

---------------------------------------------------------
Title: Supersonic Downflows in the Solar Chromosphere are Very Common
Authors: Aznar Cuadrado, R.; Solanki, S. K.; Lagg, A.
2005ESASP.596E..49A Altcode: 2005ccmf.confE..49A
No abstract at ADS

---------------------------------------------------------
Title: Evidence of Enceladus and Tethys microsignatures
Authors: Paranicas, C.; Mitchell, D. G.; Livi, S.; Krimigis, S. M.;
Roussos, E.; Krupp, N.; Woch, J.; Lagg, A.; Saur, J.; Turner, F. S.
2005GeoRL..3220101P Altcode:
We present evidence of two icy satellite microsignatures in the Cassini
LEMMS data. Just upstream of Enceladus, a deep and narrow decrease in
the flux of several MeV electrons is consistent with a recent absorption
by that moon. This microsignature is collocated with a deep depletion in
the MeV proton flux. The proton feature is much wider than the satellite
diameter, suggesting multiple interactions and/or losses to the E Ring
and neutral gas. An observed increase in proton flux toward the planet
suggests a possible inner magnetospheric source. A decrease in the
low energy electron intensity downstream of Tethys is also consistent
with a microsignature approximately the size of the satellite that has
drifted slightly toward the planet near midnight. Modeling suggests
that microsignatures near Tethys' orbit would persist for more than
a complete rotation of Saturn and the radial diffusion coefficient is
about 10-9 RS2/s.

---------------------------------------------------------
Title: Dynamics of energetic particles and neutrals in Saturn's
variable magnetosphere: results from the MIMI investigation
Authors: Krimigis, S. M.; Mitchell, D. G.; Hamilton, D. C.; Krupp,
N.; Livi, S.; Roelof, E. C.; Dandouras, J.; Mauk, B. H.; Brandt,
P. C.; Paranicas, C. P.; Saur, J.; Armstrong, T. P.; Bolton, S.;
Cheng, A. F.; Gloeckler, G.; Hill, M. E.; Hsieh, K. C.; Ip, W. H.;
Lagg, A.; Lanzerotti, L. J.; McEntire, R. W.; Williams, D. J.
2005DPS....37.0604K Altcode: 2005BAAS...37Q.626K
The Magnetospheric IMaging Instrument (MIMI) comprises three sensors:
the Ion and Neutral Camera (INCA) provides images using energetic
neutral atoms (ENA) and ions; the Charge-Energy-Mass-Spectrometer
(CHEMS) determines the mass and charge state of ions; and the
Low Energy Magnetospheric Measurement System (LEMMS) measures ion
and electron distributions using a dual field-of-view telescope
(Krimigis et al, Space Sci Rev,114, 2333-329, 2004). Measurements
by MIMI after Saturn orbit insertion on 1 July 2004 have elucidated
several new features of the planet's magnetosphere. These include: (1)
A dynamical magnetosphere with an11-hour periodicity. (2) The first
remotely-sensed radiation belt inside Saturn's D-ring. (3) Abundant
water products in the magnetospheric plasma &gt; or = 10 kev/charge,
but little nitrogen (N+/O+&lt;0.05); neutral gas is found to be a
major mechanism for particle loss. (4) Injections of plasma in the
∼4-11Rs and also &gt;20Rs corotate with the planet and can last for
several days. (5) Activity (possibly analogous to Earth's substorms)
occurs in Saturn's magnetotail in the 20-40 Rs region during large
magnetospheric disturbances; this has not been observed during quiet
times. (6) Field-aligned electron beams occur in the dawn to early
morning sector as close as ∼10 Rs, and map to latitudes of observed
Saturn aurora. (7) A gas cloud around Titan with dimensions &gt; 1 Rs,
with strong high ( 3200 km) altitude ENA emissions forms a continuous,
asymmetric “halo." (8) Titan's emission is centered on moon--hot plasma
interaction with the exosphere; changing intensity depends on variable
(x10-100) ion population and magnetic field orientation about Titan. (9)
Upstream ion events have been measured to large (&lt;50 to &gt;
800 Rs) distances; several are enriched in oxygen ions, suggesting a
magnetospheric origin. The observations will be presented and discussed
in the context of current models of Saturn's magnetosphere.

---------------------------------------------------------
Title: The Saturnian plasma sheet as revealed by energetic particle
measurements
Authors: Krupp, N.; Lagg, A.; Woch, J.; Krimigis, S. M.; Livi, S.;
Mitchell, D. G.; Roelof, E. C.; Paranicas, C.; Mauk, B. H.; Hamilton,
D. C.; Armstrong, T. P.; Dougherty, M. K.
2005GeoRL..3220S03K Altcode:
Since July 2004 Cassini is in orbit around Saturn providing in-situ
measurements of the Saturnian magnetosphere. One of the three sensors
of the Magnetospheric Imaging Instrument (MIMI) is the Low Energy
Magnetospheric Measurement System (LEMMS) that responds to energetic
particles which can serve as indicators of key regions (Krimigis et al.,
2005) and ongoing plasma processes in the magnetosphere. In this paper
we identify and characterize, based on energetic particle and magnetic
field measurements, the radiation belts, the plasma sheet, and the lobe
region. The transition between plasma sheet and lobe region sometimes
occurs very rapidly, and sometimes occurs with the period of Saturn's
rotation. We explain the highly variable nature of the Saturnian plasma
sheet as a combination of the geometry of the Cassini trajectory,
together with the variable location of the boundary between open and
closed field lines caused by a strong localized magnetic anomaly in
the Saturnian field.

---------------------------------------------------------
Title: Ion abundance ratios in the Jovian magnetosphere
Authors: Radioti, A.; Krupp, N.; Woch, J.; Lagg, A.; Glassmeier,
K. -H.; Waldrop, L. S.
2005JGRA..110.7225R Altcode: 2005JGRA..11007225R
Galileo, as the first orbiting spacecraft around Jupiter, provides
the opportunity to study globally the composition of the energetic ion
population in the equatorial plane of the Jovian magnetosphere. This
enables us to derive the relative importance of the various sources and
sinks of plasma and energetic particles in the largest magnetosphere of
our solar system. In this paper we use data from the Energetic Particles
Detector (EPD) on board Galileo and derive relative ion abundance
ratio maps of S/O, S/He, O/He, and p/He. We extend the previous work
in terms of global coverage, species, and energy range. In addition we
compare them with previous results and especially with those derived on
board Voyager 2. We found that the S/O abundance ratio is relatively
constant throughout the magnetosphere decreasing slightly with radial
distance. Within the error bars the S/O ratios could be reproduced. Only
a minor energy dependence is observed for this ratio pointing to a
common source for both ions. The S/He-, O/He-, and p/He-ratios decrease
with increasing radial distance, furthering the notion that sulfur,
oxygen, and protons originate mainly from a source within the Jovian
system, in contrast with helium, which originates from the solar
wind. A spectral kink observed at energies of several 100 keV/nuc
for all species and most pronounced for helium explains the observed
energy dependence of the ratios relative to helium. Differences in
the abundance ratios up to more than one order of magnitude between
sequential orbits are evidence of large temporal variations taking
place in the Jovian magnetosphere. These variations and the strong
energy dependence can explain the differences between the results
derived from Galileo EPD measurements and those from Voyager data.

---------------------------------------------------------
Title: On the fine structure of sunspot penumbrae. II. The nature
of the Evershed flow
Authors: Borrero, J. M.; Lagg, A.; Solanki, S. K.; Collados, M.
2005A&A...436..333B Altcode: 2005astro.ph..3677B
We investigate the fine structure of the sunspot penumbra by means of
a model that allows for a flux tube in horizontal pressure balance
with the magnetic background atmosphere in which it is embedded. We
apply this model to spectropolarimetric observations of two neutral
iron lines at 1.56 μm and invert several radial cuts in the penumbra
of the same sunspot at two different heliocentric angles. In the inner
part of the penumbra we find hot flux tubes that are somewhat inclined
to the horizontal. They become gradually more horizontal and cooler
with increasing radial distance. This is accompanied by an increase
in the velocity of the plasma and a decrease of the gas pressure
difference between flux tube and the background component. At large
radial distances the flow speed exceeds the critical speed and evidence
is found for the formation of a shock front. These results are in good
agreement with simulations of the penumbral fine structure and provide
strong support for the siphon flow as the physical mechanism driving
the Evershed flow.

---------------------------------------------------------
Title: Jovian plasma sheet morphology: particle and field observations
by the Galileo spacecraft
Authors: Waldrop, L. S.; Fritz, T. A.; Kivelson, M. G.; Khurana, K.;
Krupp, N.; Lagg, A.
2005P&SS...53..681W Altcode:
We present results from an investigation of the plasma sheet
encounter signatures observed in the Jovian magnetosphere by the
Energetic Particles Detector (EPD) and Magnetometer (MAG) onboard the
Galileo spacecraft. Maxima in ion flux were used to identify over 500
spacecraft encounters with the plasma sheet between radial distances
from Jupiter from 20 to 140 RJ during the first 25 orbits
(4 years of data). Typical signatures of plasma sheet encounters
show a characteristic periodicity of either 5 or 10 hours that is
attributed to an oscillation in the relative distance between the
spacecraft and the plasma sheet that arises from the combination of
planetary rotation and offset magnetic and rotational axes. However,
the energetic particle and field data also display much variability,
including instances of intense fluxes having little to no periodicity
that persist for several Jovian rotation periods. Abrupt changes in
the mean distance between the plasma sheet and the spacecraft are
suggested to account for some of the transitions between typical flux
periodicities associated with plasma sheet encounters. Additional
changes in the plasma sheet thickness and/or amplitude of the plasma
sheet displacement from the location of the spacecraft are required to
explain the cases where the periodicity breaks down but fluxes remain
high. These changes in plasma sheet characteristics do not display an
obvious periodicity; however, the observations suggest that dawn/dusk
asymmetries in both the structure of the plasma sheet and the frequency
of anomalous plasma sheet encounters are present. Evidence of a thin,
well-ordered plasma sheet is found out to 110 RJ in the
dawn and midnight local time sectors, while the dusk magnetosphere
is characterized by a thicker, more disordered plasma sheet and has a
potentially more pronounced response to an impulsive trigger. Temporal
variations associated with changing solar wind conditions are suggested
to account for the anomalous plasma sheet encounters there.

---------------------------------------------------------
Title: How To Use Magnetic Field Information For Coronal Loop
Identification
Authors: Wiegelmann, T.; Inhester, B.; Lagg, A.; Solanki, S. K.
2005SoPh..228...67W Altcode: 2008arXiv0801.4573W
The structure of the solar corona is dominated by the magnetic field
because the magnetic pressure is about four orders of magnitude
higher than the plasma pressure. Due to the high conductivity the
emitting coronal plasma (visible, e.g., in SOHO/EIT) outlines the
magnetic field lines. The gradient of the emitting plasma structures
is significantly lower parallel to the magnetic field lines than
in the perpendicular direction. Consequently information regarding
the coronal magnetic field can be used for the interpretation of
coronal plasma structures. We extrapolate the coronal magnetic field
from photospheric magnetic field measurements into the corona. The
extrapolation method depends on assumptions regarding coronal currents,
e.g., potential fields (current-free) or force-free fields (current
parallel to magnetic field). As a next step we project the reconstructed
3D magnetic field lines on an EIT-image and compare with the emitting
plasma structures. Coronal loops are identified as closed magnetic
field lines with a high emissivity in EIT and a small gradient of the
emissivity along the magnetic field.

---------------------------------------------------------
Title: Saturn's Dynamic Magnetosphere: Energetic Particles and
Neutrals from the Magnetospheric Imaging Instrument (MIMI)
Authors: Krimigis, S. M.; Mitchell, D. G.; Hamilton, D. C.; Krupp, N.;
Livi, S.; Roelof, E. C.; Dandouras, I.; Mauk, B. H.; Brandt, P. C.;
Paranicas, C.; Saur, J.; Armstrong, T. P.; Bolton, S.; Cheng, A. F.;
Gloeckler, G.; Hill, M. E.; Hsieh, K.; Ip, W.; Lagg, A.; Lanzerotti,
L. J.; McEntire, R. W.; Williams, D. J.
2005AGUSM.P14A..04K Altcode:
The MIMI investigation comprises three sensors: the Ion and Neutral
Camera (INCA) provides images using energetic neutral atoms (ENA)
and ions; the Charge-Energy-Mass-Spectrometer (CHEMS) determines
the mass and charge state of ions; and the Low Energy Magnetospheric
Measurement System (LEMMS) measures ion and electron distributions using
a dual field-of-view telescope (Krimigis et al., 2004). Measurements
by MIMI following Saturn orbit insertion on 1 July 2004 revealed:
(1) a dynamical magnetosphere with a day-night asymmetry and an
11-hour periodicity; (2) several water-product ions (O+, OH+, H2O+),
but little N+; (3) inferred quantities of neutral gas sufficient to
cause major losses in the trapped ions and electrons in the middle and
inner magnetosphere; (4) a Titan exosphere that is a copious source of
energetic neutral atoms (ENA); (5) a previously unknown radiation belt
residing inward of the D-ring that is most likely the result of double
charge-exchange between the main radiation belt and the upper layers
of Saturn's exosphere. Finally, MIMI data show evidence of injections
of plasma on the night-side of the planet, some substorm-like in
the magnetotail and others in the 7-10 RS region that subsequently
corotate with the planet for a number of days before dissipating. The
observations will be presented and discussed in the context of current
theoretical models of Saturn's magnetosphere. Krimigis, S. M., et al.,
Magnetosphere Imaging Instrument (MIMI) on the Cassini Mission to
Saturn/Titan, Space Sci. Rev., volume 114/1-4, pp 233-329, 2004.

---------------------------------------------------------
Title: Comparing magnetic field extrapolations with measurements of
magnetic loops
Authors: Wiegelmann, T.; Lagg, A.; Solanki, S. K.; Inhester, B.;
Woch, J.
2005A&A...433..701W Altcode: 2008arXiv0801.4519W
We compare magnetic field extrapolations from a photospheric magnetogram
with the observationally inferred structure of magnetic loops in
a newly developed active region. This is the first time that the
reconstructed 3D-topology of the magnetic field is available to test
the extrapolations. We compare the observations with potential fields,
linear force-free fields and non-linear force-free fields. This
comparison reveals that a potential field extrapolation is not
suitable for a reconstruction of the magnetic field in this young,
developing active region. The inclusion of field-line-parallel
electric currents, the so called force-free approach, gives much better
results. Furthermore, a non-linear force-free computation reproduces
the observations better than the linear force-free approximation,
although no free parameters are available in the former case.

---------------------------------------------------------
Title: Overview of Results from the Cassini Magnetospheric Imaging
Instrument (MIMI) During the First Year of Operations
Authors: Krimigis, S. M.; Mitchell, D. G.; Hamilton, D. C.; Krupp, N.;
Livi, S.; Roelof, E. C.; Dandouras, J.; Mauk, B. H.; Brandt, J. P.;
Paranicas, C.; Saur, J.; Armsrong, T. P.; Bolton, S.; Cheng, A. F.;
Gloeckler, G.; Hsieh, K. C.; Ip, W. -H.; Lagg, A.; Lanzerotti, L. J.;
McEntire, R. W.; Williams, D. J.
2005LPI....36.1361K Altcode:
A high-level overview of MIMI results includes corotation of
the magnetosphere, overwhelming presence of water-product ions,
identification of a radiation belt inside the D-ring, and inferred
presence of neutral gas absorbing ions and electrons inward of Dione's
orbit.

---------------------------------------------------------
Title: Mass release at Jupiter: Substorm-like processes in the
Jovian magnetotail
Authors: Kronberg, E. A.; Woch, J.; Krupp, N.; Lagg, A.; Khurana,
K. K.; Glassmeier, K. -H.
2005JGRA..110.3211K Altcode: 2005JGRA..11003211K
The Jupiter orbiting spacecraft Galileo has provided evidence that
the Jovian magnetotail is subject to a periodic process with typical
timescales of several days by which the Jovian system is presumably
releasing its excess iogenic mass. The mass release process resembles
a terrestrial substorm in the sense of a global reconfiguration of the
magnetotail. During the initial "loading" phase the plasma convection is
at a moderate speed in the corotation direction and the Jovian plasma
sheet appears to be in a stable configuration. In the release phase,
reconnection through a thinned current sheet leads to radially inward
and outward plasma flows and the ejection of plasmoids. Storage of
magnetic energy in the lobe region seems not to be the prime driver
of the reconfiguration process. Therefore the role of the solar
wind as energy source is of less importance than for terrestrial
substorms. Instead, it can be envisaged that plasma loading of fast
rotating magnetic flux tubes and the associated centrifugal forces
drive the reconfiguration process.

---------------------------------------------------------
Title: Dynamics of Saturn's Magnetosphere from MIMI During Cassini's
Orbital Insertion
Authors: Krimigis, S. M.; Mitchell, D. G.; Hamilton, D. C.; Krupp,
N.; Livi, S.; Roelof, E. C.; Dandouras, J.; Armstrong, T. P.; Mauk,
B. H.; Paranicas, C.; Brandt, P. C.; Bolton, S.; Cheng, A. F.; Choo,
T.; Gloeckler, G.; Hayes, J.; Hsieh, K. C.; Ip, W. -H.; Jaskulek, S.;
Keath, E. P.; Kirsch, E.; Kusterer, M.; Lagg, A.; Lanzerotti, L. J.;
LaVallee, D.; Manweiler, J.; McEntire, R. W.; Rasmuss, W.; Saur, J.;
Turner, F. S.; Williams, D. J.; Woch, J.
2005Sci...307.1270K Altcode:
The Magnetospheric Imaging Instrument (MIMI) onboard the Cassini
spacecraft observed the saturnian magnetosphere from January 2004
until Saturn orbit insertion (SOI) on 1 July 2004. The MIMI sensors
observed frequent energetic particle activity in interplanetary space
for several months before SOI. When the imaging sensor was switched
to its energetic neutral atom (ENA) operating mode on 20 February
2004, at ~103 times Saturn's radius RS (0.43
astronomical units), a weak but persistent signal was observed from the
magnetosphere. About 10 days before SOI, the magnetosphere exhibited
a day-night asymmetry that varied with an ~11-hour periodicity. Once
Cassini entered the magnetosphere, in situ measurements showed
high concentrations of H+, H2+,
O+, OH+, and H2O+ and low
concentrations of N+. The radial dependence of ion intensity
profiles implies neutral gas densities sufficient to produce high loss
rates of trapped ions from the middle and inner magnetosphere. ENA
imaging has revealed a radiation belt that resides inward of the D
ring and is probably the result of double charge exchange between the
main radiation belt and the upper layers of Saturn's exosphere.

---------------------------------------------------------
Title: Signature of Current Sheets as Seen by Tip at VTT in the HeI
Multiplet at 1083.0 nm
Authors: Aznar Cuadrado, R.; Solanki, S. K.; Lagg, A.; Thomas, R. M.
2004ESASP.575..593A Altcode: 2004soho...15..593A
No abstract at ADS

---------------------------------------------------------
Title: Structure of Saturn's Magnetosphere as Revealed by Energetic
Particles
Authors: Krupp, N.; Woch, J.; Lagg, A.; Lim, J.; Krimigis, S. M.;
Mitchell, D. G.; Roelof, E. C.; Mauk, B. H.; Paranicas, C.; Livi,
S.; Armstrong, T. P.; Dougherty, M. K.; Kurth, W. S.; Louarn, P.;
Dandouras, I.; Hamilton, D. C.
2004AGUFM.P54A..06K Altcode:
At the end of June/beginning of July 2004 Cassini entered the
magnetosphere of Saturn, 24 years after the last encounter of a
spacecraft with the planet in 1981. Cassini entered the magnetosphere
at about 08:00 local time 15 degrees below the equatorial plane,
crossed the ring plane at a distance of 158500 km from the planet
and reached 80230 km during closest approach, much closer than the
smallest distance of Voyager. We report on results from the Low Energy
Magnetospheric Measurement System (LEMMS), one out of three detector
systems of the Magnetospheric Imaging Instrument (MIMI). MIMI/LEMMS
is designed to investigate the global configuration and topology
of the Kronian magnetosphere and to study dynamical processes. Its
double-ended sensor is able to detect energetic electrons (15 keV- 5
MeV) and ions with energies above 30 keV separately. Several different
regions inside the magnetosphere could be identified through changes
and differences in the energetic particle characteristics: A lobe
region with low ion and electron intensities, a plasma sheet region
with higher intensities and very abrupt changes when the spacecraft
enters/leaves the plasma sheet, the ring current region close to the
planet with the highest measured intensities, and the region above the
rings with extremely low particle intensities near background. Besides
the very high intensities in the main radiation belts close to the
planet and the very low intensities above the rings around closest
approach results of MIMI/LEMMS observed the Kronian magnetosphere
in a highly dynamic state indicated by so-called injection events and
quasi-periodic fluctuations of the intensities with a period of about an
hour. These periodicities have also been observed in magnetic field and
plasma wave data on board Cassini. Preliminary analysis correlate these
fluctuations with the motion of the plasma sheet of Saturn which either
has a wavy surface or corrugated sheet structure within this period.

---------------------------------------------------------
Title: Imaging of Saturn's magnetosphere and energetic particles
obsered during Cassini's orbit insertion at Saturn
Authors: Krimigis, S. M.; Mitchell, D. G.; Hamilton, D. C.; Krupp,
N.; Livi, S.; Roelof, E. C.; Dandouras, J.; Armstrong, T. P.; Mauk,
B. H.; Paranicas, C.; Brandt, P.; Bolton, S.; Cheng, A. F.; Choo,
T.; Gloeckler, G.; Hayes, J.; Hsieh, K. C.; Ip, W. -H.; Jaskulek, S.;
Keath, E. P.; Kirsch, E.; Kusterer, M.; Lagg, A.; Lanzerotti, L. J.;
LaVallee, D.; Manweiler, J.; McEntire, R. W.; Rasmuss, W.; Saur, J.;
Turner, F. S.; Williams, D. J.
2004DPS....36.0202K Altcode: 2004BAAS...36.1067K
The MIMI investigation comprises three sensors, the Ion and Neutral
Camera (INCA), Charge-Energy-Mass-Spectrometer (CHEMS), and Low Energy
Magnetospheric Measurement System (LEMMS) covering the energy ranges
7 keV/nuc &lt; E &lt; 200 keV/nuc (ions/neutrals), 3 &lt; E &lt; 230
keV/e (ions), and 0.02 &lt; E &lt;18 Mev (ions)/0.015 &lt; E &lt;1 Mev
(electrons), respectively. Also, LEMMS measures high-energy electrons
(E &gt; 3 Mev) and protons (1.6 &lt; E &lt; 160 Mev) from the back end
of the dual field-of-view telescope. The Saturn observation sequences
began in January, 2004 and culminated in Saturn Orbit Insertion (SOI)
on July 1, 2004. The MIMI sensors observed substantial activity in
interplanetary space for several months prior to SOI, including several
interplanetary shocks associated with corotating interaction regions,
as well as numerous increases most likely originating from particle
streams in the vicinity of the Saturnian bow shock. When the INCA
sensor was switched to its energetic neutral atom (ENA) operating
mode on day 51, at ∼ 1000 RS (0.43 AU), a weak signal was observed
denoting the presence of Saturn's magnetosphere. Results during SOI
revealed a dynamical magnetosphere with a day-night asymmetry and an
11-hour periodicity; several water-product ions (O+, OH+, H2O+), but
no N+; a substantial gas cloud around Titan, but little evidence of
a discernible torus; and sufficient (inferred) quantities of neutral
gas that cause major losses to trapped ions in the middle and inner
magnetosphere. Finally, INCA imaging has revealed a previously unknown
radiation belt that resides inside the D-ring that is most likely
the result of double charge-exchange between the main radiation belt
and the upper layers of Saturn's exosphere. The observations will be
presented and discussed in the context of current theoretical models.

---------------------------------------------------------
Title: Energetic particle observations in the vicinity of Jupiter:
Cassini MIMI/LEMMS results
Authors: Krupp, N.; Woch, J.; Lagg, A.; Livi, S.; Mitchell, D. G.;
Krimigis, S. M.; Dougherty, M. K.; Hanlon, P. G.; Armstrong, T. P.;
Espinosa, S. A.
2004JGRA..109.9S10K Altcode:
We report on energetic particle measurements from the Low
Energy Magnetospheric Measurement System (LEMMS) on board the
Cassini spacecraft during the Jupiter flyby (October 2000 to April
2001). Cassini passed Jupiter on its way to Saturn on the dusk flank of
the magnetosphere and explored for the first time the dusk-to-midnight
magnetosheath of the planet. The flyby period can be divided into
three distinct regimes where energetic particle parameter changes
are observed. The first period (October 2000 to 10 January 2001)
covers the approach phase toward the planet, including bow shock
crossings in and out of the magnetosheath as well as the closest
approach. In this period, LEMMS responded on solar wind pressure
pulses and recorded the passing of two interplanetary shocks. Hours
before the first bow shock crossing, low-energy particle intensity
increases were observed, possibly with Jovian origin. Before the
closest approach approach to the planet two inbound and one outbound bow
shock crossings have been observed. The second period (9-10 January)
is the period where Cassini briefly entered the magnetosphere twice
at about 200 RJ. LEMMS data are only available during a
large portion of the second encounter. Inside the magnetosphere the
energetic electrons showed a bidirectional pitch angle distribution
along the magnetic field, indicative of a closed magnetic field
configuration predominantly in the north-south direction. In addition,
quasi-periodic electron intensity variations with periods of ≈40
min were observed. The third period (January to April 2001) covers the
distances between 205 and 800 RJ. The spacecraft was skimming
along the bow shock boundary in the dusk-to-midnight sector. More than
44 inbound and outbound bow shock crossings have been observed. The
most interesting magnetosheath encounter occurred between day 19 and
day 28 at distances between 300 and 400 RJ. In that period,
LEMMS observed strong intensification of MeV-electron fluxes to values
similar to those measured inside the magnetosphere as reported by
[2002]. Most of these increases in electrons were associated with
sign changes in the north-south component of the magnetic field. We
interpret these observations in terms of magnetic dayside reconnection
and particle leakage through the duskside magnetosheath.

---------------------------------------------------------
Title: Energetic ion characteristics and neutral gas interactions
in Jupiter's magnetosphere
Authors: Mauk, B. H.; Mitchell, D. G.; McEntire, R. W.; Paranicas,
C. P.; Roelof, E. C.; Williams, D. J.; Krimigis, S. M.; Lagg, A.
2004JGRA..109.9S12M Altcode:
Spectra, integral moments, and composition (H, He, O, S) of
energetic ions (50 keV to 50 MeV) are presented for selected Jupiter
magnetospheric positions near the equator between radial distances of
∼6 to ∼46 Jupiter radii (RJ), as revealed by analysis of
the Galileo Energetic Particle Detector data. These characteristics are
then used as the basis of interpreting and modeling reported signatures
of energetic ion/neutral gas interactions within Jupiter's inner
magnetosphere, particularly energetic neutral atom emissions measured
during the Cassini spacecraft flyby of Jupiter. Key findings include
the following: (1) sulfur ions significantly dominate the energetic
(≥50 keV) ion density and pressure at all radial distances &gt;7
RJ; (2) protons dominate integral number and energy intensity
planetward of 20-25 RJ; (3) a distinct signature of local,
equatorial acceleration of energetic protons is revealed between Io
(5.9 RJ) and Europa (9.4 RJ); (4) significant
spectral and compositional signatures of neutral gas interactions are
also revealed between the orbits of Io and Europa; (5) a previously
reported significant depletion of ring current ion populations between
Io and Europa during the early-phase operation of Galileo (∼1995), as
compared with observations obtained during the Voyager epoch (1979),
has persisted and probably deepened during later Galileo phases
(1999); and (6) detailed energetic neutral atom emission modeling,
based on the in situ results reported here, further constrains recent
estimates of the contents of the neutral gas torus of Europa.

---------------------------------------------------------
Title: Thermal-magnetic relation in a sunspot and a map of its
Wilson depression
Authors: Mathew, S. K.; Solanki, S. K.; Lagg, A.; Collados, M.;
Borrero, J. M.; Berdyugina, S.
2004A&A...422..693M Altcode:
We present relations between thermal and magnetic quantities in a
simple, isolated sunspot, as deduced from the inversion of 1.56 μm
spectropolarimetric data. We used a combination of two infrared Fe I
lines at 15 648.5 Å and 15 652.8 Å/ in the inversions. Due to the
high Zeeman sensitivity of these lines, we can study this relationship
in the entire sunspot. The relevant parameters were derived both as a
function of location within the sunspot and of height in the atmosphere
using an inversion technique based on response functions. In this paper
we relate the magnetic vector with temperature. We find a non-linear
relationship between the various components of the magnetic vector and
temperature, which confirm the results from earlier investigations. We
also computed the Wilson depression and the plasma β for the observed
sunspot and compare our results with earlier findings.

---------------------------------------------------------
Title: On the fine structure of sunspot penumbrae. I. A quantitative
comparison of two semiempirical models with implications for the
Evershed effect
Authors: Borrero, J. M.; Solanki, S. K.; Bellot Rubio, L. R.; Lagg,
A.; Mathew, S. K.
2004A&A...422.1093B Altcode:
Sunspot penumbrae exhibit prominent fine structure. Different
interpretations of spectropolarimetric observations suggest different,
sometimes contradictory, properties of this fine structure. In this
paper we show that the results of inversions of penumbral infrared
profiles based on one-component models with gradients of the atmospheric
parameters and two-component models without gradients are compatible
with each other. Our analysis reconciles the results of previous
investigations and provides further support for the picture that sunspot
penumbrae are composed of penumbral flux tubes embedded in a magnetic
background. The magnetic field in the tubes is more horizontal and
weaker than that of the background atmosphere. While the tubes carry
most of the Evershed flow, the background is essentially at rest. We
notice also that the magnetic field strength in the flux tubes drops
much more slowly with radial distance than the background field. This
finding is discussed as a possible driver for the Evershed flow.

---------------------------------------------------------
Title: Energetic electrons in the inner part of the Jovian
magnetosphere and their relation to auroral emissions
Authors: TomáS, A. T.; Woch, J.; Krupp, N.; Lagg, A.; Glassmeier,
K. -H.; Kurth, W. S.
2004JGRA..109.6203T Altcode:
The energetic particle distribution in the magnetosphere of
Jupiter changes significantly between the inner and the middle
magnetosphere. One of the most prominent changes is a transition
of the electron pitch angle distribution (PAD) from a pancake to
a bidirectional distribution. The transition is a persistent and
localized feature defining a distinct spatial boundary between 10 and
17 RJ. We discuss the possible relation between the PAD
boundary and some of the observed structures in the Jovian aurora. A
comparison between the Hubble Space Telescope observations and the
predicted ionospheric footprints of the PAD boundary indicates a good
correlation, with a discrete belt of emissions equatorward of the main
auroral oval. Furthermore, the precipitation energy flux associated with
the energetic electron distribution at the PAD boundary is compatible
with the brightness range of these auroral emissions.

---------------------------------------------------------
Title: Charged Particle Losses near the Inner Galilean Satellites
Authors: Paranicas, C.; Lagg, A.; Krupp, N.; Woch, J.; Mauk, B. H.
2004AGUSMSM51A..05P Altcode:
To study the losses of energetic charged particles in the inner
magnetosphere of Jupiter, we have calculated proton phase space
densities from the Galileo Energetic Particles Detector (EPD) data. The
phase space density as a function of L shell is believed to obey a
diffusion equation. In previous calculations, the phase space density
in the inner magnetosphere has been shown to decrease inward toward
the planet, suggesting sources at large distances, and losses due to
satellite sweeping and other effects. The Galileo data reveal features
indicating a loss process near the satellites Io and Europa. We also
verify a region of strong loss just outside the orbital radius of
Io. We will present loss rate estimates for the relevant physical
processes within a diffusion context. These loss rate calculations,
for instance, allow us to place an upper bound on the neutral gas
distribution in radius (or L shell).

---------------------------------------------------------
Title: Europa's Neutral Gas Torus
Authors: Mauk, B. H.; Mitchell, D. G.; McEntire, R. W.; Paranicas,
C. P.; Roelof, E. C.; Williams, D. J.; Krimigis, S. M.; Lagg, A.
2004AGUSMSA22A..03M Altcode:
In-situ energetic ion measurements from the Galileo spacecraft and
remote energetic neutral atom (ENA) images from the Cassini spacecraft
have been previously interpreted as revealing an unexpectedly massive
torus of gas co-orbiting with Jupiter's moon Europa (Lagg et al.,
2003; Mauk et al., 2003). Here we report on the results of detailed
modeling of the ENA emission process from the Europa regions. Updates
to the distribution and composition of the trapped energetic ion
populations are included in the models, as are considerations of the
partitioning of the gas products into multiple atomic and molecular
species. Comparisons between the models and the Cassini observations
reveal a torus with a total gas content equal to (0.5 +/- 0.2) E34 atoms
plus molecules. This value is higher than, but within a factor of 3 of,
an estimate inferred from a prediction of gas densities derived from
Voyager plasma measurements and modeling of the interaction between the
plasmas and the gases assumed to be emanating from Europa (Schreier
et al., 1993). Lagg, A., N. Krupp, J. Woch, and D. J. Williams,
Geophys. Res. Lett., 30, DOI 10.1029/2003GL017214, 2003. Mauk, B. H.,
D. G. Mitchell, S. M. Krimigs, E. C. Roelof, and C. P. Paranicas,
Nature, 241, 920, 2003. Schreier, S., A. Eviatar, V. M. Vasyliunas,
and J. D. Richardson, J. Geophys. Res., 98, 21231, 1993.

---------------------------------------------------------
Title: Changes of the energetic particles characteristics in the
inner part of the Jovian magnetosphere: a topological study
Authors: Tomás, A.; Woch, J.; Krupp, N.; Lagg, A.; Glassmeier,
K. -H.; Dougherty, M. K.; Hanlon, P. G.
2004P&SS...52..491T Altcode:
Based on 33 Galileo passages through the inner part of the Jovian
magnetosphere, the properties of the energetic charged particle
population are investigated. Pronounced changes in the particle
intensities, and in their energy and pitch angle distributions (PADs)
are generally observed. The good coverage in local time and radial
distance provided by Galileo allowed to trace the location of the most
distinct changes within the equatorial plane. Independent of local
time they occur at distances between 10 and 30RJ. Within
this region particle intensities drop by several orders of magnitude
and the energy spectra softens considerably. However, most prominent
is a change of the electron PAD from a pancake or trapped (maximum at
90°) to a distribution which maximises at different pitch angle values
(bi-directional or butterfly distributions). The change occurs rapidly,
usually within the time resolution of the measurements, giving rise to
a sharp and distinct boundary. This boundary is located dependent on
the orbit between 10 and 17RJ. It does not exhibit striking
local time dependencies, specifically a pronounced dawn-dusk asymmetry,
with the exception of the boundary being slightly closer to the planet
near noon compared to the other local times. The change in the electron
pitch angle distribution occurs in a region where the magnetic field
topology is still close to a dipolar field configuration. The softening
of the particle energy spectra is collocated with the transition of the
magnetic field from a dipolar to a current sheet topology. Possible
connections to and implications for the Jovian high-latitude aurora
are addressed.

---------------------------------------------------------
Title: Retrieval of the full magnetic vector with the He I multiplet
at 1083 nm. Maps of an emerging flux region
Authors: Lagg, A.; Woch, J.; Krupp, N.; Solanki, S. K.
2004A&A...414.1109L Altcode:
A technique is presented to invert Stokes profiles of the He I 1083
nm multiplet lines in order to obtain the full magnetic vector and the
line-of-sight velocity. The technique makes use of spectropolarimetry
connected with the Zeeman effect supplemented by a simple Hanle effect
based diagnostic when appropriate. It takes into account effects
like line saturation, magnetooptieffects, etc. and is coupled with a
genetic algorithm, which ensures that the global minimum in a goodness
of fit hypersurface is found. Tests using both artificial and real
data demonstrated the robustness of the method. As an illustration
maps of deduced parameters of an emerging flux region are shown and
briefly discussed.

---------------------------------------------------------
Title: Energetic Particles In The Vicinity Of Saturn: Cassini
Mimi/Lemms Observations
Authors: Krupp, N.; Lagg, A.; Woch, J.; Krimigis, S. M.; Livi, S.;
Mitchell, D. G.; Hamilton, D. C.; Armstrong, T. P.; Lanzerotti, L. J.
2004cosp...35.2723K Altcode: 2004cosp.meet.2723K
The Cassini-Huygens mission, launched in 1997, finally reached Saturn in
July 2004. One of the science goals of the mission is to investigate the
magnetosphere of Saturn, the interaction of the magnetospheric plasma
and energetic particle population with the rings, moons and the solar
wind. The Low Energy Magnetospheric Measurement System LEMMS (one out
of three sensors of the Magnetospheric Imaging Instrument MIMI onboard
Cassini) is able to measure low- and high-energy electrons and ions
separately in the energy range between 0.015 to 5 MeV for electrons
and 0.03 to about 160 MeV for ions. The instrument is mounted on a
programmable scan platform allowing measurements from all direction
within the scan plane which most of the time will be perpendicular to
the ecliptic. This configuration will allow a good coverage in pitch
angles. We present details of the first results in the vicinity of
Saturn in and outside of the Kronian magnetosphere during the approach
phase and insertion phase until July 2004. We will discuss these
results by comparing them with early Pioneer and Voyager measurements.

---------------------------------------------------------
Title: Temporal evolution of chromospheric downflows
Authors: Lagg, Andreas; Woch, J.; Krupp, N.; Gandorfer, A.; Solanki,
S. K.
2004IAUS..223..279L Altcode: 2005IAUS..223..279L
At the footpoints of loops spanning a site of flux emergence, earlier
investigated in the papers by Solanki et al. (2003) and Lagg et
al. (2004), we find large redshifts in the He 1083 nm line coexisting
with an almost unshifted component. The speed associated with these
redshifts reaches values as high as 40 km/s. We interpret these
downflows in the context of several models: the free-fall downflow of
matter along vertical field lines (Schmidt et al. 2000), the redshift
by downward propagating acoustic waves (Hansteen 1993) and the motion
of condensation regions to either side of loop footpoints (Müller et
al. 2003). We present the temporal evolution of these redshifts and
reconstruct the magnetic field vector in these regions for both the
redshifted and the unshifted atmospheric component.

---------------------------------------------------------
Title: The structure and dynamics of the Jovian energetic particle
distribution
Authors: Woch, J.; Krupp, N.; Lagg, A.; Tomás, A.
2004AdSpR..33.2030W Altcode:
We review the recent progress made in unravelling the properties of
the energetic particle population in the magnetosphere of Jupiter. The
importance of the findings with respect to mechanisms driving the
dynamics of the Jovian system is addressed. We concentrate on the
implications of phase space density variations for particle loss and
source mechanism. Systematic local time and radial dependencies observed
in the characteristics of the energetic ion and electron distributions,
specifically the particle pitch angle distributions and particle flow
pattern are discussed. They possibly bear important information for
disentangling those mechanisms responsible for driving the Jovian aurora
and for identifying the magnetospheric source populations. Furthermore,
we discuss transient particle events in the tail which point to the
importance of reconnection for the tail dynamics.

---------------------------------------------------------
Title: Long-term dynamics of the inner Jovian electron radiation belts
Authors: Sicard, A.; Bourdarie, S.; Krupp, N.; Lagg, A.; Boscher,
D.; Santos-Costa, D.; Gerard, E.; Galopeau, P.; Bolton, S.; Sault,
R.; Williams, D. J.
2004AdSpR..33.2039S Altcode:
Long-term variations of total Jovian synchrotron emission are well
known to vary slowly in time. Several hypotheses have been proposed
to explain these variations, they can be solar wind driven and/or
induced by the geometrical effect of the declination of the Earth in
the jovicentric coordinates, DE. However, until now, not any
of them have been definitely proved. We propose here to investigate,
this long-term dynamics based on appropriate simulation from a 3D
model, Salammbô-3D. This model has been developed to study spatial
distribution of electrons in the inner Jovian radiation belts. We
will carry out two different approaches, the first one being based on
synchrotron simulation from the Salammbô code and the second one being
based on GALILEO EPD measurements. Two-dimensional images of Jupiter
synchrotron emission can be obtained from our model, for any geometrical
configuration ( λIII(CML), DE). Comparisons show
a good agreement between modeling results and VLA observations. With
Salammbô-3D, we can also study long-term variations of total Jovian
synchrotron emission. The role of the two geometrical factors,
λIII(CML) and DE, will be analyzed. First, we
will present beaming curves (evolution of Jovian synchrotron emission
in terms of λIII(CML)), resulting from the simulation to
validate the geometry of the system in the code. Then, the evolution
of the non-thermal flux density of synchrotron emission, in terms
of DE, joviographic declination of the Earth, will be
studied. With the help of simulations resulting from Salammbô-3D,
we will try to discriminate between geometrical induced variations
and natural dynamics. On the other hand we will investigate on GALILEO
EPD measurements from 1995 until now, restricted to 5-10 Rj, to find
out any similarity with the long-term variations of non-thermal flux
density of synchrotron emission.

---------------------------------------------------------
Title: Microsignatures of satellite and ring absorption events
Authors: Ip, W. H.; Hsu, W. H.; Lagg, A.; Krupp, N.; Woch, J.; Livi,
S.; Armstrong, T.; Krimigis, S. K.
2004cosp...35.1517I Altcode: 2004cosp.meet.1517I
Energetic charged particles interact with particulate material
in planetary magnetospheres by impact absorption and surface
sputtering. This process is of fundamental importance in providing a
source of neutral gas and ions of chemical composition different from
that of the solar wind. At the same time, the absorption of the trapped
charged particles will create dips in the corresponding intensity
distribution. Such absorption features, sometimes of just a few tens to
hundreds of km in dimension, could serve as a sensitive probe to the
existence of unseen small satellites and rings. In this presentation
we will first make a brief review of the previous observations and
theoretical interpretations of microsignatures detected in the Saturnian
magnetosphere by the Pioneer 11 and Voyager spacecraft. This is to be
followed by an examination of the opportunityy provided by the Cassini
mission in making a detailed census of small satellites and narrow
ring arcs of transient nature by a combination of charged particle
experiments and imaging devices.

---------------------------------------------------------
Title: Dynamics of the Jovian magnetosphere
Authors: Krupp, N.; Vasyliunas, V. M.; Woch, J.; Lagg, A.; Khurana,
K. K.; Kivelson, M. G.; Mauk, B. H.; Roelof, E. C.; Williams, D. J.;
Krimigis, S. M.; Kurth, W. S.; Frank, L. A.; Paterson, W. R.
2004jpsm.book..617K Altcode:
Radial transport; Short-term variations: plasma interchange, injection
events, ULF waves in Jupiter's magnetosphere; Long-term variations:
phenomena at the planetary spin period, plasmasheet dynamics;
Boundary phenomena: variability of boundaries, boundary layers,
boundary fluctuations, injection of particles into interplanetary space.

---------------------------------------------------------
Title: The configuration of Jupiter's magnetosphere
Authors: Khurana, Krishan K.; Kivelson, Margaret G.; Vasyliunas,
Vytenis M.; Krupp, Norbert; Woch, Joachim; Lagg, Andreas; Mauk,
Barry H.; Kurth, William S.
2004jpsm.book..593K Altcode:
The inner magnetosphere: internal magnetic field, plasma sources,
radiation belts; The middle magnetosphere: current sheet morphology
and structural models, thermal and energetic plasmas, magnetic field
models of the current sheet, the structure of the middle magnetosphere,
bend-back of the field and plasma outflow; The outer magnetosphere: the
Chapman-Ferraro currents, magnetotail; Plasma diffusion and convection:
how plasma moves outwards, observations; Plasma acceleration and heating
in Jupiter's magnetosphere: ionization and charge exchange, adiabatic
processes, reconnection and magnetotail processes, low-altitude and
auroral processes; Local time asymmetries: influence of solar wind.

---------------------------------------------------------
Title: Successful Measurement of the Full Magnetic Vector Near the
Base of the Solar Corona
Authors: Solanki, S. K.; Lagg, A.; Woch, J.; Krupp, N.; Landi
Degl'Innocenti, E.; Collados, M.
2003AGUFMSH41D..05S Altcode:
The measurement of coronal fields has in the past generally been
restricted to the field strength or to only some of the components of
the magnetic vector. We present here a technique for measuring the full
magnetic vector near the base of the solar corona. As an application
we report on observations of a developing active region with ongoing
magnetic flux emergence. The data allow the first measurement of the 3-D
structure of magnetic loops. They also provide the first detection of an
electric current sheet located near the base of the solar corona. Such
current sheets or tangential discontinuities of the coronal magnetic
field have long been thought to be a major source of coronal heating.

---------------------------------------------------------
Title: Three dimensional structure of a regular sunspot from the
inversion of IR Stokes profiles
Authors: Mathew, S. K.; Lagg, A.; Solanki, S. K.; Collados, M.;
Borrero, J. M.; Berdyugina, S.; Krupp, N.; Woch, J.; Frutiger, C.
2003A&A...410..695M Altcode:
The magnetic, thermal and velocity structure of a regular sunspot,
observed close to solar disk center is presented. Spectropolarimetric
data obtained with the Tenerife Infrared Polarimeter (TIP) in two
infrared FeI lines at 15 648.5 Å and 15 652.8 Å are inverted
employing a technique based on response functions to retrieve the
atmospheric stratification at every point in the sunspot. In order
to improve the results for the umbra, profiles of Zeeman split OH
lines blending the FeI 15 652.8 Å are also consistently fit. Thus
we obtain maps of temperature, line-of-sight velocity, magnetic
field strength, inclination, and azimuth, as a function of both
location within the sunspot and height in the atmosphere. We present
these maps for an optical depth range between log tau5 =
0 and log tau5 = -1.5, where these lines provide accurate
results. We find decreasing magnetic field strength with increasing
height all over the sunspot, with a particularly large vertical field
gradient of ~ -4 G km-1 in the umbra. We also observe the
so called “spine” structures in the penumbra, i.e. extended radial
features with a stronger and more vertical magnetic field than the
surroundings. Also we found that the magnetic field zenith angle
increases with height. From the velocity map it is clear that the
Evershed flow avoids the spines and mostly concentrates in the more
inclined intervening field. The field inclination at a few locations
in the outer penumbra in lower layers goes beyond 90o. These
locations coincide with the strongest flows in the velocity map.

---------------------------------------------------------
Title: Three-dimensional magnetic field topology in a region of
solar coronal heating
Authors: Solanki, S. K.; Lagg, A.; Woch, J.; Krupp, N.; Collados, M.
2003Natur.425..692S Altcode:
Flares and X-ray jets on the Sun arise in active regions where magnetic
flux emerges from the solar interior amd interacts with the ambient
magnetic field. The interactions are believed to occur in electric
current sheets separating regions of opposite magnetic polarity. The
current sheets located in the corona or upper chromosphere have long
been thought to act as an important source of coronal heating, requiring
their location in the corona or upper chromosphere. The dynamics and
energetics of these sheets are governed by a complex magnetic field
structure that, until now, has been difficult to measure. Here we report
the determination of the full magnetic vector in an interaction region
near the base of the solar corona. The observations reveal two magnetic
features that characterize young active regions on the Sun: a set of
rising magnetic loops and a tangential discontinuity of the magnetic
field direction, the latter being the observational signature of an
electric current sheet. This provides strong support for coronal heating
models based on the dissipation of magnetic energy at current sheets.

---------------------------------------------------------
Title: Molecular Lines as Diagnostics of Solar and Stellar Magnetic
Fields
Authors: Berdyugina, S. V.; Solanki, S. K.; Lagg, A.
2003csss...12..210B Altcode:
Thanks to recent advances in theory we can now calculate molecular
line profiles in the presence of magnetic fields with high accuracy,
both in the Zeeman and Paschen-Back regimes (Berdyugina et al. 2000;
Berdyugina &amp; Solanki 2001a). The synthetic Stokes profiles of
various molecular species (e.g. TiO, OH, MgH, CN, FeH) have been
compared with profiles observed in sunspots. The agreement between
the theory and observations is remarkable. For example, the mutually
opposite polarities of different OH lines are reproduced without
invoking any free parameters, except the magnetic field strength and
sunspot temperature. Introducing molecular lines into the inversion
of sunspot spectra leads to significant improvements in the deduced
magnetic field vector. Here we investigate how molecular lines can be
used to deduce magnetic parameters of cool stars. We find that such
lines are of great interest for measuring magnetic fields on cooler
stars and in starspots.

---------------------------------------------------------
Title: Quiet-Sun inter-network magnetic fields observed in the
infrared
Authors: Khomenko, E. V.; Collados, M.; Solanki, S. K.; Lagg, A.;
Trujillo Bueno, J.
2003A&A...408.1115K Altcode:
This paper presents the results of an investigation of the quiet Sun's
magnetic field based on high-resolution infrared spectropolarimetric
observations obtained with the Tenerife Infrared Polarimeter (TIP)
at the German VTT of the Observatorio del Teide. We observed two very
quiet regions at disc centre. The seeing was exceptionally good during
both observing runs, being excellent during one of them. In both cases
the network was intentionally avoided to the extent possible, to focus
the analysis on the characteristics of the weak polarization signals
of the inter-network regions. We find that the Stokes V profile of
Fe I 15648 Å line in almost 50% of the pixels and Stokes Q and/or
U in 20% of the pixels have a signal above 10-3 (in units
of continuum intensity Ic), which is significantly above
the noise level of 2-3 x 10-4. This implies that we detect
fluxes as low as 2 x 1015 Mx/px. We find evidence that we
have detected most of the net flux that is in principle detectable at
1” resolution with the Zeeman effect. The observed linear
polarization resulting from the transverse Zeeman effect indicates that
the magnetic fields have a broad range of inclinations, although most
of the pixels show polarization signatures which imply an inclination
of about 20o. Nearly 30% of the selected V-profiles have
irregular shapes with 3 or more lobes, suggesting mixed polarities with
different LOS velocity within the resolution element. The profiles are
classified using a single value decomposition approach. The spatial
distribution of the magnetic signal shows that profiles of different
classes (having different velocities, splitting, asymmetries) are
clustered together and form patches, close to the spatial resolution
in size. Most of the field is found to be located in intergranular
lanes. The statistical properties of the mainly inter-network field
sampled by these observations are presented, showing that most of
the observed fields are weak with relatively few kG features. The
field strength distribution peaks at 350 G and has a FWHM of 300
G. Other parameters, such as profile asymmetries, filling factors and
line-of-sight velocities are also determined and discussed. Based
on observations with the German Vacuum Tower Telescope (VTT) operated by
the Kiepenheuer-Institut für Sonnenphysik at the Spanish Observatorio
del Teide of the Instituto de Astrofísica de Canarias (IAC).

---------------------------------------------------------
Title: Infrared Polarimetry at the MPAe: The Solar Atmosphere from
the Photosphere to the Upper Chromosphere
Authors: Lagg, Andreas; Woch, Joachim; Solanki, Sami K.; Mathew,
Shibu; Borrero, Juan M.; Krupp, N.; Raouafi, N. E.
2003ANS...324...29L Altcode: 2003ANS...324..D04L
No abstract at ADS

---------------------------------------------------------
Title: In-situ observations of a neutral gas torus at Europa
Authors: Lagg, A.; Krupp, N.; Woch, J.; Williams, D. J.
2003GeoRL..30.1556L Altcode: 2003GeoRL..30k..10L
A persistent pattern in the pitch angle distributions of energetic
protons near the orbit of Europa has been observed with the Energetic
Particles Detector (EPD) on board the Galileo spacecraft during each
of the Europa orbit crossings in the last 7 years. The proton fluxes
at energies larger than 220 keV peak at equatorial pitch angles of 90°
whereas fluxes of lower energy protons (80-220 keV) at this pitch angle
are depleted. We propose that a Jupiter-surrounding neutral gas torus
in the vicinity of the orbit of Europa is responsible for the depletion
of energetic particle fluxes by charge exchange collisions. In order
to reproduce the observed depletion signature an average neutral number
density of 20 to 50 cm-3 is required.

---------------------------------------------------------
Title: Velocity Profiles Of Energetic Particles In The Jovian
Magnetosphere
Authors: Krupp, N.; Woch, J.; Lagg, A.
2003EAEJA....10013K Altcode:
During the 34 orbits of the Galileo spacecraft around Jupiter in the
years 1995--2003 the Energetic Particles Detector EPD measured angular
distributions of energetic ions in Jupiter's equatorial plane. These
distributions have been used to derive global velocity profiles of
energetic ions. We present examples of these velocity profiles at
different local times and radial distances and discuss local time
asymmetries in Jupiter's magnetosphere.

---------------------------------------------------------
Title: Changes of the energetic particle characteristics in the
inner jovian magnetosphere and the relation to auroral features
Authors: Tomas, A.; Woch, J.; Krupp, N.; Lagg, A.; Glassmeier, K. -H.;
Dougherty, M. K.; Hanlon, P. G.; Khurana, K. K.; Prange, R.
2003EAEJA.....9357T Altcode:
Based on 33 Galileo passages through the inner part of the jovian
magnetosphere the properties of the energetic charged particle
population are investigated. Pronounced changes in the particle
intensities, and in their energy and pitch angle distribution are
generally observed. The good coverage in local time and radial
distance provided by Galileo allowed to trace the location of the
most distinct changes within the equatorial plane. Independent on
local time they occur at distances between 10 R_J and 30 R_J. Within
this region particle intensities drop by several orders of magnitude
and the energy spectra softens considerably. However, most prominent
is a change of the electron pitch angle distribution from a pancake
or trapped to a bi-directional distribution with maxima close to
0^0 and 180^0. The change occurs rapidly, usually within the time
resolution of the measurements, giving rise to a sharp and distinct
boundary. This boundary is located dependent on the orbit between 10
and 17 R_J, and occurs in a region where the magnetic field topology
is still close to a dipolar field configuration. In order to establish
a relation to and implications for the jovian high-latitude aurora,
the mentioned region was then mapped into the ionosphere of Jupiter,
using the Khurana and the VIP4 model for the tracing of magnetic field
lines. Estimation of the electron precipitation flux and a detailed
comparison with HST observations suggest that the sharp pitch angle
boundary is related to the transition between the belt of diffuse
auroras and the main auroral oval of Jupiter.

---------------------------------------------------------
Title: New Molecular Indicators of Sunspot Magnetic Fields: Infrared
OH Lines
Authors: Berdyugina, S. V.; Solanki, S. K.; Lagg, A.
2003ASPC..286..299B Altcode: 2003ctmf.conf..299B
No abstract at ADS

---------------------------------------------------------
Title: Structure of a simple sunspot from the inversion of IR
spectral data
Authors: Mathew, S. K.; Solanki, S. K.; Lagg, A.; Collados, M.;
Berdyugina, S. V.; Frutiger, C.; Krupp, N.; Woch, J.
2003AN....324..388M Altcode:
Analysis of spectral data of two neighboring infrared lines, Fe i
15648.5 Å (g = 3) and Fe i 15652.9 Å (g_eff = 1.53) are carried out
for a simple sunspot when it was near the solar disk center (mu = 0.92),
to understand the basic structure of sunspot magnetic field. Inversions
of Stokes profiles are carried out to derive different atmospheric
parameters both as a function of location within the sunspot and height
in the atmosphere. As a result of the inversion we have obtained maps
of magnetic field strength, temperature, line-of-sight velocity, field
inclination and azimuth for different optical depth layers between log
(tau_ {5}) = 0 and log (tau_ {5}) = -2.0 . In this paper we present
few results from our inversion for a layer averaged between log (tau_
{5}) from 0.0 to -0.5.

---------------------------------------------------------
Title: Modeling the Fine Structure of a Sunspot Penumbra through
the Inversion of Stokes Profiles
Authors: Borrero, J. M.; Lagg, A.; Solanki, S. K.; Frutiger, C.;
Collados, M.; Bellot Rubio, L. R.
2003ASPC..286..235B Altcode: 2003ctmf.conf..235B
No abstract at ADS

---------------------------------------------------------
Title: Thermal-magnetic relation of a sunspot as inferred from the
inversion of 1.5 μm spectral data
Authors: Mathew, S. K.; Solanki, S. K.; Lagg, A.; Krupp, N.; Woch,
J.; Collados, M.; Berdyugina, S.; Frutiger, C.
2002ESASP.505..501M Altcode: 2002IAUCo.188..501M; 2002solm.conf..501M
We present the thermal-magnetic relation in a simple, isolated sunspot
deduced from the inversion of 1.56 μm spectropolarimetric data. Due to
the high Zeeman sensitivity of the g = 3, Fe I 1.5648 μm line, we can
study this relationship in the entire sunspot. An inversion technique
based on response functions is used to derive various parameters,
both as a function of location within the sunspot and of height in the
atmosphere. In this paper we attempt to relate field strength, vertical
and radial field components and the field inclination with temperature.

---------------------------------------------------------
Title: Statistical properties of magnetic fields in intranetwork
Authors: Khomenko, E. V.; Collados, M.; Lagg, A.; Solanki, S. K.;
Trujillo Bueno, J.
2002ESASP.505..445K Altcode: 2002IAUCo.188..445K; 2002solm.conf..445K
We report a study of the quiet sun's magnetic field based
on high-resolution infrared spectropolarimetric observations
(TIP/VTT). We find that in almost 50% of the pixels Stokes V and in 15%
the Stokes Q and/or U profiles have a signal above 10-3. The
statistical properties of the mainly intranetwork field sampled by these
observations are presented, showing that most of the observed fields
are weak (the field strength distribution peaks at 350 G and has a FWHM
of 300 G) with very few kG features. The magnetized regions occupy a
very small fill fractions (about 2%). The field changes properties on
granular spatial scales and the size of the patches formed by similar
profiles is close to 1". Most of the parameters of the observed
polarization profiles show correlations with granulation parameters.

---------------------------------------------------------
Title: Leakage of energetic particles from Jupiter's dusk
magnetosphere: Dual spacecraft observations
Authors: Krupp, N.; Woch, J.; Lagg, A.; Espinosa, S. A.; Livi, S.;
Krimigis, S. M.; Mitchell, D. G.; Williams, D. J.; Cheng, A. F.; Mauk,
B. H.; McEntire, R. W.; Armstrong, T. P.; Hamilton, D. C.; Gloeckler,
G.; Dandouras, J.; Lanzerotti, L. J.
2002GeoRL..29.1736K Altcode: 2002GeoRL..29o..26K
For the first time, two spacecraft, Galileo and Cassini, observed
Jupiter's magnetosphere simultaneously for nearly half a year between
October 2000 and March 2001. This provided an unprecedented opportunity
to disentangle spatial and temporal aspects of the dynamics of the
Jovian magnetosphere. In this paper we report new results on the source
of the leakage of energetic particles (electrons with energy 15 keV
to several MeV and ions with energy &gt; 30 keV) from the dusk side
of the magnetosphere. The dual spacecraft measurements show clearly
that magnetospheric particles leak directly into the interplanetary
medium from the closed magnetosphere, and are the source for the
“upstream” particle events [Baker et al., 1996; Zwickl et al., 1981;
Krimigis, 1992; Haggerty and Armstrong, 1999; Anagnostopoulos et al.,
1998] that have been reported from instruments during prior single
spacecraft encounters with the planet. These events, consisting of
high-energy particles of Jovian origin, have been observed throughout
the heliosphere [Baker and Van Allen, 1976] and their propagation
has recently been modelled [Fichtner et al., 2000; Ferreira et al.,
2001]. Jupiter then is an important contributor to the interplanetary
charged particle fluxes, especially within an astronomical unit of
the planet.

---------------------------------------------------------
Title: Particle bursts in the Jovian magnetosphere: Evidence for a
near-Jupiter neutral line
Authors: Woch, Joachim; Krupp, Norbert; Lagg, Andreas
2002GeoRL..29.1138W Altcode: 2002GeoRL..29g..42W
In the magnetosphere of Jupiter the plasma convection is driven
by the planetary rotation up to considerable distances from the
planet. However, at larger distances the rotational flow is often
disrupted by explosive events, seen as jets of energetic particles
propagating in the radial direction. These events are observed
very frequently and can be regarded as an intrinsic property of the
Jovian system. A statistical survey shows that the burst events are
concentrated in the post-midnight tail region. Inward directed bursts
dominate closer to the planet, outward directed bursts further away
from the planet. The transition from mainly inward to mainly outward
directed bursts defines the most probable location of a near-Jupiter
neutral line. The findings corroborate early models which postulate that
magnetic flux tubes heavily loaded with plasma originating from the moon
Io will be stretched by the centrifugal forces up to such a degree that
spontaneous reconnection sets in. This leads to acceleration of plasma
and the release of plasmoids into interplanetary space. The process
may also drive the recently observed auroral dawn storms at Jupiter.

---------------------------------------------------------
Title: A nebula of gases from Io surrounding Jupiter
Authors: Krimigis, Stamatios M.; Mitchell, Donald G.; Hamilton, Douglas
C.; Dandouras, Jannis; Armstrong, Thomas P.; Bolton, Scott J.; Cheng,
Andrew F.; Gloeckler, George; Hsieh, K. C.; Keath, Edwin P.; Krupp,
Norbert; Lagg, Andreas; Lanzerotti, Louis J.; Livi, Stefano; Mauk,
Barry H.; McEntire, Richard W.; Roelof, Edmond C.; Wilken, Berend;
Williams, Donald J.
2002Natur.415..994K Altcode:
Several planetary missions have reported the presence of substantial
numbers of energetic ions and electrons surrounding Jupiter;
relativistic electrons are observable up to several astronomical units
(AU) from the planet. A population of energetic (&gt;30keV) neutral
particles also has been reported, but the instrumentation was not
able to determine the mass or charge state of the particles, which
were subsequently labelled energetic neutral atoms. Although images
showing the presence of the trace element sodium were obtained,
the source and identity of the neutral atoms-and their overall
significance relative to the loss of charged particles from Jupiter's
magnetosphere-were unknown. Here we report the discovery by the Cassini
spacecraft of a fast (&gt;103kms-1) and hot
magnetospheric neutral wind extending more than 0.5AU from Jupiter,
and the presence of energetic neutral atoms (both hot and cold) that
have been accelerated by the electric field in the solar wind. We
suggest that these atoms originate in volcanic gases from Io, undergo
significant evolution through various electromagnetic interactions,
escape Jupiter's magnetosphere and then populate the environment
around the planet. Thus a `nebula' is created that extends outwards
over hundreds of jovian radii.

---------------------------------------------------------
Title: New Results of Energetic Particle Observations In The Duskside
Jovian Magnetosphere
Authors: Krupp, N.; Woch, J.; Lagg, A.
2002EGSGA..27.2855K Altcode:
We report on new results from in-situ energetic particle measurements
in the vicin- ity of Jupiter observed during the last year 2001
and the beginning of 2002 by the Energetic Particles Detector EPD
onboard the Galileo spacecraft. We concentrate on so-called realtime
data in and outside the Jovian magnetosphere from the outer dusk-
side Jovian magnetosphere out the magnetopause location at about 100
planetary radii (RJ). EPD, which measures electrons (15-884 keV),
ions (30-3200 keV) and protons (80-1250 keV), Helium (27-1000 keV/n),
Oxygen (12-562 keV/n), and Sulfur (16-310 keV/n) ions separately,
has the capability to derive energy spectra, relative ion compo-
sition and angular distributions. This allows us to investigate
relative ion composition, acceleration mechanisms and particle motion
in regions of the Jovian magnetosphere where nearly no other data are
available. Preliminary results show that the Jovian mag- netosphere
at a local time of 1700 LT was very active and dynamic in early 2002
with very sharp boundary crossings around 80-100 RJ. The results will
be discussed in the context of previous data sets at other local times
and will be compared with MHD simulations

---------------------------------------------------------
Title: The structure and dynamics of the Jovian energetic particle
population
Authors: Woch, J.; Krupp, N.; Lagg, A.
2002cosp...34E.936W Altcode: 2002cosp.meetE.936W
The comprehensive measurements performed by the Galileo spacecraft
allowed for the first time to study in detail a planetary
magnetosphere other than the Earth's one. The observations confirmed
besides similarities the existence of significant differences. In
contrast to the solar wind-controlled terrestrial magnetosphere,
the plasma convection in the magnetosphere of Jupiter is driven by
the fast planetary rotation up to considerable distances from the
planet. Furthermore, strong internal plasma sources give rise to
dynamical processes unknown from Earth. We will review the structure
and dynamics of the Jovian system as deduced from energetic particle
observations, focussing on the particle convection pattern, the
formation of a near-Jupiter neutral line, substorm-like instabilities,
and outer boundary layer processes. We will address their relevance
for the high-latitude aurorae at Jupiter and discuss the relative
importance of internal and solar wind energy sources.

---------------------------------------------------------
Title: Particle Emission From The Earth and Jupiter Magnetospheres
Measured By The Cassini-lemms-particle Detector
Authors: Kirsch, E.; Krupp, N.; Lagg, A.; Dougherty, M. K.; Krimigis,
S. M.; Livi, S.; Armstrong, T. P.
2002EGSGA..27.5423K Altcode:
The Cassini spacecraft passed the Earth in August 1999 and Jupiter in
December 2000 on its way to planet Saturn. The Low Energy Magnetospheric
Measurement System LEMMS (Ep &gt; 30 keV, Ee &gt; 15 keV) which is a
part of the MIMI instrument ob- served particle bursts emitted from the
Earth and Jupiter magnetospheres. We study the flux, energy and time
behavior of such bursts and compare them for both planets. It will
be discussed whether substorm or other effects are responsible for
the particle acceleration and how the particles reach interplanetary
magnetic field lines. We com- pare our results also with measurements
obtained earlier by other Earth satellites and the Ulysses mission to
planet Jupiter.

---------------------------------------------------------
Title: Energetic particle measurements during the earth swing-by of
the Cassini spacecraft in August 1999
Authors: Lagg, A.; Krupp, N.; Livi, S.; Woch, J.; Krimigis, S. M.;
Dougherty, M. K.
2001JGR...10630209L Altcode:
We report on energetic particle measurements from the Low-Energy
Magnetospheric Measurement System (LEMMS) aboard the Cassini
spacecraft during the Earth swing-by maneuver in August 1999. LEMMS
is capable of identifying the energy and incidence direction of
energetic ions and electrons with energies of a few tens of keV
to several tens of MeV. Cassini flew by Earth with a velocity of
16 kms-1 or 9 Earth radii (RE) per hour,
which means that the entire dayside magnetosphere was passed within
1 hour. This fast flyby trajectory of the spacecraft provided a
snapshot of the Earth's magnetosphere where key regions were passed
within a few hours instead of typically tens of hours or days for
orbiting spacecraft. The measurements provide a means to show the
performance of the instrument's capabilities as well as to test models
of energetic particle distributions within the Earth's magnetosphere
[e.g. Sibeck et al., 1987]. Particle pitch angle distributions (PADs)
on the inbound pass along the 1300 magnetic local time (MLT) meridian
gradually changed from normal distributions (maximum at 90° pitch
angle) to butterfly pitch angle distributions (maximum at intermediate
pitch angles). Close to the plasmapause, LEMMS observed field-aligned
bidirectional distributions. During the outbound pass through the inner
magnetosphere at 0130 MLT, pitch angle distributions are generally
close to isotropic. Shortly after a substorm onset, identified by
ground-based observations and aboard the Polar spacecraft [Khan et al.,
this issue], LEMMS observed an energy-time dispersed enhancement in
the differential flux of low-energy electrons. We further address the
question of whether signatures of the Earth magnetotail were observed
at distances beyond 5000RE when Cassini passed through
the Earth's downstream region. LEMMS measured a series of particle
increases during that time. The angular distributions during these
enhancements show that most of these particles did indeed arrive from
the Earth's direction. Nevertheless, the lack of singly charged heavy
ions does not allow for a definite identification of this event as a
deep-tail encounter.

---------------------------------------------------------
Title: Global flows of energetic ions in Jupiter's equatorial plane:
First-order approximation
Authors: Krupp, N.; Lagg, A.; Livi, S.; Wilken, B.; Woch, J.; Roelof,
E. C.; Williams, D. J.
2001JGR...10626017K Altcode:
Galileo, as the first orbiting spacecraft in an outer planet's
magnetosphere, provides the opportunity to study global energetic
ion distributions in Jupiter's magnetosphere. We present directional
anisotropies of energetic ion distributions measured by the Galileo
Energetic Particles Detector (EPD). The EPD measurements of proton
(80-1050 keV), oxygen (26-562 keV/nucleon), and sulfur (16-310
keV/nucleon) distributions cover a wide energy range. Spatially,
the data set includes measurements from 6 to 142 Jovian radii
(RJ) and covers all local times inside the Jovian
magnetosphere. For each species a single detector head scans almost
the entire sky (~4π sr), producing the three-dimensional angular
distributions from which the anisotropies are derived. Consequently,
the resulting anisotropy estimates are both global and robust. Such
anisotropies, generally produced by convective flow, ion intensity
gradients, and field-aligned components, have long been used to
estimate flow velocities and to locate spatial boundaries within
magnetospheres. They can therefore provide vital information on
magnetospheric circulation and dynamics. We find that the EPD
measured anisotropies in the Jovian magnetosphere are dominated by
a component in the corotational direction punctuated by episodic
radial components, both inward and outward. Under the assumption
that anisotropies are produced predominantly by convective flow, we
derive flow velocities of protons, oxygen ions, and sulfur ions. The
validity of that approach is supported by the fact that these three
independently derived flow velocities agree, to a large extent, in
this approximation. Thus, for the first time, we are able to derive
the global flow pattern in a magnetosphere of an outer planet. In
a comparison between the first-order EPD flow velocities and those
predicted by a magnetohydrodynamic (MHD) simulation of the Jovian
magnetosphere, we find that qualitatively the directions appear similar,
although no firm evidence of steady outflow of ions has been observed
at distances covered by Galileo. A first rough comparison indicates
that the measured first-order flow velocities are higher by at least
a factor of 1.5 than the MHD simulation results.

---------------------------------------------------------
Title: Observations in Jupiter's Vicinity with the Magnetospheric
Imaging Instrument (MIMI) During Cassini/Huygens Flyby (October
2000-March 2001)
Authors: Krimigis, S. M.; Mitchell, D. G.; Hamilton, D. G.; Livi,
S.; Armstrong, T. P.; Cheng, A. F.; Dandouras, J.; Gloeckler, G.;
Hsieh, K. C.; Ip, W. H.; Keath, E. P.; Kirsch, E.; Krupp, N.; Lagg,
A.; Lanzerotti, L. J.; Mauk, B. H.; McEntire, R. W.; Roelof, E. C.;
Wilken, B.; Williams, D. J.
2001AGUSM...P51A11K Altcode:
The MIMI investigation comprises three sensors, the Ion and Neutral
Camera (INCA), Charge-Energy-Mass-Spectrometer (CHEMS), and Low Energy
Magnetospheric Measurement System (LEMMS) covering the energy ranges
7 keV/nuc &lt;E&lt;3 Mev/nuc (ions/ &lt; 400 keV/nuc neutrals),
3&lt;E&lt;230 keV/e (ions), and 0.02 &lt;E&lt;18 Mev (ions)/0.015
&lt;E&lt;1 Mev (electrons), respectively. Also, LEMMS measures
high-energy electrons (E&gt;3 Mev) and protons (1.6 &lt; E &lt; 160 Mev)
from the back end of the dual field-of-view telescope. MIMI obtained
data intermittently from October 2000 to March 2001 corresponding
to distances of ~ 103RJ upstream to ~ 103RJ downstream of the
planet. The first unambiguous image of Energetic Neutral Atoms (ENA)
was seen at ~ 1155RJ upstream and occupied one pixel in INCA at ~
3% statistics. The observed intensity in the range ~ 15 to 55 keV
(hydrogen) corresponds to ~ 0.08 (cm2 s keV)-1 when scaled to 100
RJ., i.e. similar to expectations based on Voyager 1 observations
some 21 years earlier. Many images were obtained through, and past,
closest approach (140 RJ; Mitchell et al, this AGU). In addition to
ENA's, the CHEMS sensor detected several ion species of Jovian (O+,
S+, SO2+, etc) and interstellar (He+) origin in the upstream medium
that manifested themselves as pick-up and accelerated components,
suggesting that cis-Jovian space is dominated by a nebula populated
by volcanic gases from Io (Hamilton, et al, this AGU). Energetic
electrons and ion events (LEMMS) were also present upstream and
marked each crossing of the extended bow shock and magnetopause of the
planet. While in the magnetosphere, field-aligned electron distributions
provided unambiguous evidence of closed field lines to at least 200
RJ downstream from Jupiter. Simultaneously, highly charged (S3+, S4+,
O3+, O2+, etc) ions were seen, suggesting that plasma outflow in the
dusk magnetotail is dominated by magnetospheric rather than solar wind
plasma. Evidence that Jovian plasmas are present to at least ~ 850RJ
downstream will be presented and implications discussed on overall
outflow of magnetospheric plasma.

---------------------------------------------------------
Title: Hot plasma heavy ion abundance in the inner Jovian
magnetosphere (/&lt;10 Rj)
Authors: Maclennan, C. G.; Lanzerotti, L. J.; Lagg, Andreas
2001P&SS...49..275M Altcode:
Knowledge of the hot plasma components of the Jovian environment is
important for several scientific problems, including the acceleration
and transport of Jovian plasmas, the stability of the plasma sheet,
and the bombardment, implantation, and sputtering of the surfaces of
Jovian moons, especially Europa. The multiple flybys of the Jovian
moon Europa during the Galileo mission have provided the opportunity to
study the time and spatial dependence of the abundance of the dominant
hot plasma (∼0.2-10 MeV/nucleon (n)) heavy ions in the innermost
region of the Jovian magnetosphere (≲10 Rj) . Reported
here are measurements made by the CMS Δ E× E telescopes in the EPD
instrument on the Galileo orbiter during the first six encounters with
the moon Europa, data taken over a period of about 1.5 years. We use
these measurements to study the hot plasma oxygen, sulfur, and sodium
abundances near and inside the Europa orbit. The values we determine
for these species in the energy range of 0.5-1.0 MeV/n are 0.67±0.05
for the S/O abundance and 0.05±0.01 for the Na/O abundance, and are
similar to previous determinations made by instruments on the Voyager
(measurements in 1979) and Ulysses (measurements in 1992) spacecraft.

---------------------------------------------------------
Title: Local time asymmetry of energetic ion anisotropies in the
Jovian magnetosphere
Authors: Krupp, N.; Woch, J.; Lagg, A.; Roelof, E. C.; Williams,
D. J.; Livi, S.; Wilken, B.
2001P&SS...49..283K Altcode:
Since December 1995 the Galileo spacecraft is in orbit around
Jupiter. Up to now the spacecraft performed 25 orbits through the Jovian
system within nearly 4 years providing an excellent data coverage in
local time specifically for distances r&lt;40 RJ. We present
first-order anisotropies measured in energetic ion distributions from
the Energetic Particles Detector (EPD) onboard Galileo. In this paper,
we concentrate on measurements in the inner Jovian magnetosphere
at distances between 6 and 40 RJ. Results from three
different ion species show a pronounced local time asymmetry in the ion
distributions at these distances especially between the dawn-prenoon
and the dusk-premidnight sector of the magnetosphere. The predominantly
first-order anisotropies in the co-rotation direction show larger
amplitudes with radial outward components in the dawn sector whereas
at dusk smaller anisotropies with small radial inward components
are observed. Under the reasonable assumption that the anisotropies
are primarily due to flow, we conclude that the flow pattern is
asymmetric in local time. The flow in the dusk sector between 10 and
40 RJ is reduced compared to the dawn region.

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Title: Energetic charged particles near Europa
Authors: Paranicas, C.; McEntire, R. W.; Cheng, A. F.; Lagg, A.;
Williams, D. J.
2000JGR...10516005P Altcode:
Galileo energetic particles detector (EPD) data are presented
from several close encounters of the spacecraft with Jupiter's
moon Europa. These data reveal significant decreases in electron
and ion count rates very close to the moon and a few Europa
radii downstream. The relation between count rate decreases and
satellite absorption is analyzed because these particles sputter
and chemically modify Europa's surface. Decreases on the plasma
wake side of the satellite have radial extents comparable to
satellite dimensions. Furthermore, some energetic particle wakes
are shifted toward Jupiter from predicted locations. At some wake
locations, electron fluxes do not get above instrument background
levels. Corresponding electrons are lost preferentially on Europa's
trailing hemisphere. Upstream of Europa during the E12 encounter,
deep decreases in energetic ion count rates are observed for some
instrument look directions. These decreases are associated with
satellite absorption because the E12 closest approach altitude is
smaller than relevant ion gyroradii. Other E12 decreases, such as a
“bite-out” corresponding to a peak in the measured magnetic field
intensity, are associated with “secondary” drifts in the radial
direction caused by the field gradient. Pitch angle distributions
measured during the E15 encounter (when Galileo was in Europa's wake)
show much higher fluxes of locally mirroring particles than would be
expected in a simple absorption signature. We suggest that a fraction
of the upstream population escapes absorption because of the pileup
of magnetic flux on Europa's trailing hemisphere.

---------------------------------------------------------
Title: Plasma sheet dynamics in the Jovian magnetotail: Signatures
For substorm-like processes ?
Authors: Woch, J.; Krupp, N.; Khurana, K. K.; Kivelson, M. G.; Roux,
A.; Perraut, S.; Louarn, P.; Lagg, A.; Williams, D. J.; Livi, S.;
Wilken, B.
1999GeoRL..26.2137W Altcode:
During Galileo's orbit G2 in 1996 the Energetic Particles Detector (EPD)
onboard the spacecraft detected a number of particle bursts with large
radial/antisunward anisotropies in the distant Jovian magnetotail [Krupp
et al., 1998]. In this letter we focus on a detailed analysis of one of
the bursts. Prior to the onset of the burst, particle intensities at low
energies increase over several hours. This phase can be interpreted as
a plasma loading phase. It ends after the onset of strong distortions in
the magnetic field with a bipolar excursion of the north-south component
being the most prominent feature. The subsequent plasma sheet encounters
show that the plasma sheet has thinned considerably. Accelerated/heated
ion beams first from the Jovian direction and then later from the tail
direction are seen at the plasma sheet and lobe interfaces and intense
radio and plasma wave emissions are detected. The event is tentatively
interpreted as a dynamical process, where the Jovian magnetotail is
internally driven unstable by mass loading of magnetic flux tubes.

---------------------------------------------------------
Title: Determination of the neutral number density in the Io torus
from Galileo-EPD measurements
Authors: Lagg, A.; Krupp, N.; Woch, J.; Livi, S.; Wilken, B.; Williams,
D. J.
1998GeoRL..25.4039L Altcode:
During the GALILEO spacecraft encounter with Io in December 1995, the
Energetic Particles Detector (EPD) [Williams et al., 1992] measured
pitch angle distributions with high spatial and temporal resolution. All
ion and electron channels show a depletion of field-aligned particles
due to the interaction of trapped particles with the ionosphere /
atmosphere of Jupiter. The medium nuclei channels, containing mainly
sulphur and oxygen ions, show a second minimum for particles moving
perpendicular to the magnetic field direction. This observation
indicates that charge exchange between the singly-charged energetic
ions and neutral atoms in the Io torus represents an important loss
mechanism for energetic ions within the Io torus regions. Additionally,
knowing the cross-sections of the involved charge exchange reactions
it is possible to calculate the average neutral number density in
the Io torus. The obtained result of ≈35 cm-3 is in good
agreement with density estimations using ground based measurements.

---------------------------------------------------------
Title: Energetic particle bursts in the predawn Jovian magnetotail
Authors: Krupp, N.; Woch, J.; Lagg, A.; Wilken, B.; Livi, S.; Williams,
D. J.
1998GeoRL..25.1249K Altcode:
From September to October 1996 the Galileo spacecraft crossed through
the distant predawn tail region of the Jovian magnetosphere. The
Energetic Particles Detector (EPD) onboard Galileo recorded a series of
energetic particle flow bursts in the region beyond 80 RJ
to the apojove at 113 RJ. The events are similar in nature
to an event observed with the hot plasma instrument (LECP) onboard
Voyager 2. The individual events last for several hours and cover the
whole energy range from 15 keV to 55 MeV. The majority of them show
considerable intensity increases which are most prominent for heavy
ions. The events exhibit high radially outward directed anisotropies
suggesting strongly collimated radial outflowing ion beams. The
Voyager event was observed beyond the corotation boundary within a
magnetospheric boundary layer termed the magnetospheric wind region and
consequently it was assumed that the underlying process is connected
with a boundary layer instability. However, the Galileo observations
show the bursts being embedded in a general corotation flow. It is
thus suggested that the flow bursts are driven by an internal plasma
sheet process possibly associated with a major re-configuration of
the Jovian magnetotail. A series of five very prominent flow bursts
observed near apojove of the orbit occurred quasi-periodically with a
repetition period of about 2.6±0.2 days which is presumably related
to an internal time constant of the Jovian magnetotail.

---------------------------------------------------------
Title: Quasi-periodic modulations of the Jovian magnetotail
Authors: Woch, J.; Krupp, N.; Lagg, A.; Wilken, B.; Livi, S.; Williams,
D. J.
1998GeoRL..25.1253W Altcode:
Measurements with the Energetic Particles Detector (EPD) on Galileo
orbit C9 in the Jovian magnetotail revealed the existence of distinct
quasi-periodic variations of energetic ion intensities which are
superimposed on the well-known 10-hour modulations due to the planetary
rotation. The intensity variations are associated with changes of the
particle energy spectra and the plasma flow pattern. They are clearly
of temporal nature and not the consequence of the spacecraft passing
through periodically separated spatial structures. The modulation period
is about 3 days. The oscillations are most pronounced throughout the
middle magnetotail regime (20 to 80 RJ), however, seem to
persist even in the deep tail region. The amplitude of the modulation is
dependent on the particle energy. The highest energies measured (about
1 MeV) show the strongest variations. Energetic particle features with
similar periodicity are observed on other Galileo orbits as well. The
cause of these modulations is unclear; however, it may be speculated
that they correspond to a quasi-periodic transition between two basic
states of the Jovian magnetotail which occur with a time constant
inherent to the Jovian magnetosphere.

---------------------------------------------------------
Title: Galileo-measured depletion of near-Io hot ring current plasmas
since the Voyager epoch
Authors: Mauk, B. H.; McEntire, R. W.; Williams, D. J.; Lagg, A.;
Roelof, E. C.; Krimigis, S. M.; Armstrong, T. P.; Fritz, T. A.;
Lanzerotti, L. J.; Roederer, J. G.; Wilken, B.
1998JGR...103.4715M Altcode:
The first mass-discriminated, hot ion distribution moments (pressure,
energy intensity) are determined for hot &gt;50-keV ions in Jupiter's
inner magnetosphere at the outer edge of Io's plasma torus by using
the Galileo energetic particle detector (EPD) data. These hot plasmas
were significantly depleted during the Galileo encounter in 1995 as
compared with the Voyager epoch of 1979. The depletion of the hot ions
is apparently caused by enhanced charge exchange losses of hot ions,
perhaps associated with enhanced emissions of neutral gases from the
volcanoes of Io. Such neutral gas enhancements could simultaneously
explain increases, reported elsewhere, in the densities of the cooler Io
torus plasmas. The hot plasma changes may explain why radial transport
interchange turbulence has been observed by Galileo in the Io torus
regions, whereas such turbulence was not apparent during the Voyager
encounters in 1979. The hot ion depletion could also play a role
in explaining the apparent differences between the Jovian auroral
configuration observed in recent years by the Hubble space telescope
and ground observers and the configuration observed by Voyager. This
possibility is much less certain, however.

---------------------------------------------------------
Title: The Energetic Particles Detector (EPD) aboard the Galileo
Spacecraft: First Results in the Jovian Magnetosphere
Authors: Krupp, N.; Lagg, A.; Livi, S.; Wilken, B.; Woch, J.; Williams,
D. J.
1997ASSL..220..319K Altcode: 1997tgms.conf..319K
No abstract at ADS