rust

explanation blue bibcodes open ADS page with paths to full text

Author name code: rust
ADS astronomy entries on 2022-09-14
author:"Rust, David Maurice"

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Title: The thermal architecture of the ESA ARIEL payload at the end
of phase B1
Authors: Morgante, G.; Terenzi, L.; Desjonqueres, L.; Eccleston,
P.; Bishop, G.; Caldwell, A.; Crook, M.; Drummond, R.; Hills, M.;
Hunt, T.; Rust, D.; Puig, L.; Tirolien, T.; Focardi, M.; Zuppella,
P.; Holmes, W.; Amiaux, J.; Czupalla, M.; Rataj, M.; Jessen, N. C.;
Pedersen, S. M.; Pascale, E.; Pace, E.; Malaguti, G.; Micela, G.
2022ExA....53..905M Altcode: 2022ExA...tmp...37M
The Atmospheric Remote-sensing Infrared Exoplanets Large-survey (ARIEL)
is the fourth medium (M4) mission selected in the context of the ESA
Cosmic Vision 2015-2025 programme, with a launch planned in 2028. During
4 years of flight operations, ARIEL will probe the chemical and physical
properties of approximately 1000 known exoplanets by observing their
atmosphere, to study how planetary systems form and evolve [1, 2]. The
mission is designed as a transit and eclipse spectroscopy survey,
operated by a 1-m class telescope feeding two instruments, the Fine
Guidance system (FGS) and the ARIEL InfraRed Spectrometer (AIRS),
that accommodate photometric and spectroscopic channels covering the
band from 0.5 to 7.8 μm in the visible to near-IR range [3, 4]. The
mission high sensitivity requirements ask for an extremely stable
thermo-mechanical platform. The payload thermal control is based on
a passive and active cooling approach. Passive cooling is achieved
by a V-Groove shields system that exploits the L2 orbit favourable
thermal conditions to cool the telescope and the optical bench to stable
temperatures &lt;60 K. The FGS focal planes operate at the optical bench
temperature while the AIRS channel detectors require a colder reference,
lower than 42 K. This is provided by an active cooling system based
on a Neon Joule-Thomson cold end, fed by a mechanical compressor. In
this paper we report the thermal architecture of the payload at the
end of Phase B1 and present the requirements that drive the design
together with the analyses results and the expected performances.

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Title: Solar Orbiter - Solar Wind Analyser Suite: Design and
performance of the Electron Analyser System for the measurement of
Solar Wind Electrons
Authors: Kataria, D. O.; Lewis, G.; Owen, C. J.; Berthomier, M.;
Leblanc, F.; Al-Janabi, K.; Anekallu, C.; Hancock, B.; Malpuss, A.;
Mayall, A.; Nicolaou, G.; Rust, D.; Watson, G.; Wicks, R. T.
2020AGUFMSH0360015K Altcode:
Solar Orbiter, launched in February 2020, will sample the near-Sun
(&lt; 0.3 AU) and high helio-latitude (&gt; 30 degrees) environments
using a state of the art complement of both in situ and remote sensing
instruments. In this contribution, we discuss details of the Electron
Analyser System (EAS), one of 3 sensor units which make up the Solar
Wind Analyser (SWA) in-situ suite of instruments. EAS consists of two
top-hat electrostatic analyser heads, each with a field of view (FOV)
of 90° x 360°, mounted orthogonal to each other to provide full
sky coverage. The analysers are enhanced performance top-hats with
a deflection system enabling electrostatic steering of the incoming
particles to cover a ±45° FOV and a variable geometric factor system
enabling electrostatic control of particle throughput by up to an
order of magnitude. The sensor is additionally mounted at the end of
a 4-metre boom, minimising FOV blockage by the spacecraft and its
appendages as well as the impact of photo- and secondary-electrons
on the low-energy solar wind plasma. Details of the design will be
presented along with charged particle optics and ground calibration
results and preliminary in-flight performance will be discussed. The
instrument has several features for flexible sampling of solar wind
electron plasma as well as for monitoring the health of the sensor
throughout the life of the mission. These will also be discussed.

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Title: The Solar Orbiter Solar Wind Analyser (SWA) suite
Authors: Owen, C. J.; Bruno, R.; Livi, S.; Louarn, P.; Al Janabi, K.;
Allegrini, F.; Amoros, C.; Baruah, R.; Barthe, A.; Berthomier, M.;
Bordon, S.; Brockley-Blatt, C.; Brysbaert, C.; Capuano, G.; Collier,
M.; DeMarco, R.; Fedorov, A.; Ford, J.; Fortunato, V.; Fratter, I.;
Galvin, A. B.; Hancock, B.; Heirtzler, D.; Kataria, D.; Kistler,
L.; Lepri, S. T.; Lewis, G.; Loeffler, C.; Marty, W.; Mathon, R.;
Mayall, A.; Mele, G.; Ogasawara, K.; Orlandi, M.; Pacros, A.; Penou,
E.; Persyn, S.; Petiot, M.; Phillips, M.; Přech, L.; Raines, J. M.;
Reden, M.; Rouillard, A. P.; Rousseau, A.; Rubiella, J.; Seran, H.;
Spencer, A.; Thomas, J. W.; Trevino, J.; Verscharen, D.; Wurz, P.;
Alapide, A.; Amoruso, L.; André, N.; Anekallu, C.; Arciuli, V.;
Arnett, K. L.; Ascolese, R.; Bancroft, C.; Bland, P.; Brysch, M.;
Calvanese, R.; Castronuovo, M.; Čermák, I.; Chornay, D.; Clemens,
S.; Coker, J.; Collinson, G.; D'Amicis, R.; Dandouras, I.; Darnley,
R.; Davies, D.; Davison, G.; De Los Santos, A.; Devoto, P.; Dirks, G.;
Edlund, E.; Fazakerley, A.; Ferris, M.; Frost, C.; Fruit, G.; Garat,
C.; Génot, V.; Gibson, W.; Gilbert, J. A.; de Giosa, V.; Gradone,
S.; Hailey, M.; Horbury, T. S.; Hunt, T.; Jacquey, C.; Johnson, M.;
Lavraud, B.; Lawrenson, A.; Leblanc, F.; Lockhart, W.; Maksimovic,
M.; Malpus, A.; Marcucci, F.; Mazelle, C.; Monti, F.; Myers, S.;
Nguyen, T.; Rodriguez-Pacheco, J.; Phillips, I.; Popecki, M.; Rees,
K.; Rogacki, S. A.; Ruane, K.; Rust, D.; Salatti, M.; Sauvaud, J. A.;
Stakhiv, M. O.; Stange, J.; Stubbs, T.; Taylor, T.; Techer, J. -D.;
Terrier, G.; Thibodeaux, R.; Urdiales, C.; Varsani, A.; Walsh, A. P.;
Watson, G.; Wheeler, P.; Willis, G.; Wimmer-Schweingruber, R. F.;
Winter, B.; Yardley, J.; Zouganelis, I.
2020A&A...642A..16O Altcode:
The Solar Orbiter mission seeks to make connections between the physical
processes occurring at the Sun or in the solar corona and the nature of
the solar wind created by those processes which is subsequently observed
at the spacecraft. The mission also targets physical processes occurring
in the solar wind itself during its journey from its source to the
spacecraft. To meet the specific mission science goals, Solar Orbiter
will be equipped with both remote-sensing and in-situ instruments
which will make unprecedented measurements of the solar atmosphere
and the inner heliosphere. A crucial set of measurements will be
provided by the Solar Wind Analyser (SWA) suite of instruments. This
suite consists of an Electron Analyser System (SWA-EAS), a Proton and
Alpha particle Sensor (SWA-PAS), and a Heavy Ion Sensor (SWA-HIS)
which are jointly served by a central control and data processing
unit (SWA-DPU). Together these sensors will measure and categorise
the vast majority of thermal and suprathermal ions and electrons in
the solar wind and determine the abundances and charge states of the
heavy ion populations. The three sensors in the SWA suite are each
based on the top hat electrostatic analyser concept, which has been
deployed on numerous space plasma missions. The SWA-EAS uses two such
heads, each of which have 360° azimuth acceptance angles and ±45°
aperture deflection plates. Together these two sensors, which are
mounted on the end of the boom, will cover a full sky field-of-view
(FoV) (except for blockages by the spacecraft and its appendages) and
measure the full 3D velocity distribution function (VDF) of solar wind
electrons in the energy range of a few eV to ∼5 keV. The SWA-PAS
instrument also uses an electrostatic analyser with a more confined
FoV (-24° to +42° × ±22.5° around the expected solar wind arrival
direction), which nevertheless is capable of measuring the full 3D VDF
of the protons and alpha particles arriving at the instrument in the
energy range from 200 eV/q to 20 keV/e. Finally, SWA-HIS measures the
composition and 3D VDFs of heavy ions in the bulk solar wind as well
as those of the major constituents in the suprathermal energy range
and those of pick-up ions. The sensor resolves the full 3D VDFs of
the prominent heavy ions at a resolution of 5 min in normal mode and
30 s in burst mode. Additionally, SWA-HIS measures 3D VDFs of alpha
particles at a 4 s resolution in burst mode. Measurements are over a
FoV of -33° to +66° × ±20° around the expected solar wind arrival
direction and at energies up to 80 keV/e. The mass resolution (m/Δm)
is &gt; 5. This paper describes how the three SWA scientific sensors,
as delivered to the spacecraft, meet or exceed the performance
requirements originally set out to achieve the mission's science
goals. We describe the motivation and specific requirements for each of
the three sensors within the SWA suite, their expected science results,
their main characteristics, and their operation through the central
SWA-DPU. We describe the combined data products that we expect to
return from the suite and provide to the Solar Orbiter Archive for use
in scientific analyses by members of the wider solar and heliospheric
communities. These unique data products will help reveal the nature of
the solar wind as a function of both heliocentric distance and solar
latitude. Indeed, SWA-HIS measurements of solar wind composition will
be the first such measurements made in the inner heliosphere. The SWA
data are crucial to efforts to link the in situ measurements of the
solar wind made at the spacecraft with remote observations of candidate
source regions. This is a novel aspect of the mission which will lead to
significant advances in our understanding of the mechanisms accelerating
and heating the solar wind, driving eruptions and other transient
phenomena on the Sun, and controlling the injection, acceleration,
and transport of the energetic particles in the heliosphere.

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Title: d'Azambuja, Lucien
Authors: Martres, M. J.; Rust, David M.
2014bea..book..528M Altcode:
No abstract at ADS

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Title: Micro-Sigmoids as Progenitors of Polar Coronal Jets
Authors: Raouafi, N. -E.; Bernasconi, P. N.; Rust, D. M.; Georgoulis,
M. K.
2012ASPC..454..299R Altcode:
Observations from the Hinode X-ray telescope (XRT) are used to study
the structure of X-ray bright points (XBPs), sources of coronal
jets. Several jet events are found to erupt from S-shaped bright
points, suggesting that coronal micro-sigmoids are progenitors of the
jets. The observations may help to explain numerous characteristics
of coronal jets, such as helical structures and shapes. They also
suggest that solar activity may be self-similar within a wide range
of scales in terms of both properties and evolution of the observed
coronal structures.

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Title: Micro-Sigmoids as Progenitors of Polar Coronal Jets
Authors: Raouafi, N. -E.; Bernasconi, P. N.; Rust, D. M.; Georgoulis,
M. K.
2010arXiv1009.2951R Altcode:
Observations from the Hinode X-ray telescope (XRT) are used to study
the structure of X-ray bright points (XBPs), sources of coronal
jets. Several jet events are found to erupt from S-shaped bright
points, suggesting that coronal micro-sigmoids are progenitors of the
jets. The observations may help to explain numerous characteristics
of coronal jets, such as helical structures and shapes. They also
suggest that solar activity may be self-similar within a wide range
of scales in terms of both properties and evolution of the observed
coronal structures.

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Title: Micro-sigmoids as Progenitors of Coronal Jets: Is Eruptive
Activity Self-similarly Multi-scaled?
Authors: Raouafi, N. -E.; Georgoulis, M. K.; Rust, D. M.; Bernasconi,
P. N.
2010ApJ...718..981R Altcode: 2010arXiv1005.4042R
Observations from the X-ray telescope (XRT) on Hinode are used to study
the nature of X-ray-bright points, sources of coronal jets. Several
jet events in the coronal holes are found to erupt from small-scale,
S-shaped bright regions. This finding suggests that coronal
micro-sigmoids may well be progenitors of coronal jets. Moreover,
the presence of these structures may explain numerous observed
characteristics of jets such as helical structures, apparent transverse
motions, and shapes. Analogous to large-scale sigmoids giving rise to
coronal mass ejections (CMEs), a promising future task would perhaps
be to investigate whether solar eruptive activity, from coronal jets to
CMEs, is self-similar in terms of properties and instability mechanisms.

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Title: Solar Magnetic Helicity Injected into the Heliosphere:
Magnitude, Balance, and Periodicities Over Solar Cycle 23
Authors: Georgoulis, M. K.; Rust, D. M.; Pevtsov, A. A.; Bernasconi,
P. N.; Kuzanyan, K. M.
2009ApJ...705L..48G Altcode:
Relying purely on solar photospheric magnetic field measurements that
cover most of solar cycle 23 (1996-2005), we calculate the total
relative magnetic helicity injected into the solar atmosphere, and
eventually shed into the heliosphere, over the latest cycle. Large
active regions dominate the helicity injection process with ~5.7
× 1045 Mx2 of total injected helicity. The
net helicity injected is lsim1% of the above output. Peculiar
active-region plasma flows account for ~80% of this helicity; the
remaining ~20% is due to solar differential rotation. The typical
helicity per active-region CME ranges between (1.8-7) × 1042
Mx2 depending on the CME velocity. Accounting for various
minor underestimation factors, we estimate a maximum helicity injection
of ~6.6 × 1045 Mx2 for solar cycle 23. Although
no significant net helicity exists over both solar hemispheres,
we recover the well-known hemispheric helicity preference, which is
significantly enhanced by the solar differential rotation. We also
find that helicity injection in the solar atmosphere is an inherently
disorganized, impulsive, and aperiodic process.

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Title: Just how much Helicity did the Sun Shed in Solar Cycle
23? Magnitude, Balance, Periodicities, and Further Implications
Authors: Georgoulis, Manolis K.; Rust, D. M.; Pevtsov, A. A.;
Bernasconi, P. N.; Kuzanyan, K. M.
2009SPD....40.0606G Altcode:
Using solar magnetic field measurements, we calculate the total
relative magnetic helicity injected in the solar atmosphere and
eventually transported to the heliosphere in the course of the
latest solar cycle. We report on (i) the magnitude of the heliospheric
helicity over cycle 23, (ii) the net helicity and its significance,
and (iii) the possible periodicities of helicity injection in
the solar atmosphere. Our simple calculations raise several questions
regarding the fundamental nature of solar magnetism. The lack of
significant net helicity may place the solar dynamo in the category
of astrophysical dynamos without a net helicity effect over an
average time scale. The strong enhancement of the hemispheric helicity
preference by solar differential rotation - although the latter has a
much weaker effect than intrinsic active-region plasma flows - warrants
further investigation. Finally, the absence of any credible periodicity
of helicity injection, in spite of numerous reported periodicities in
solar activity, perhaps prompts the re-evaluation of the notion that the
Sun works through a sequence of internal cycles: active-region emergence
and evolution appears as an inherently disorganized, aperiodic process.

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Title: On the Helical Fields Guiding Near-Relativistic Electron
Beams in the Heliosphere
Authors: Rust, David M.; Haggerty, D. K.; Georgoulis, M. K.;
Stenborg, G.
2009SPD....40.3202R Altcode:
Wavelet processing of the LASCO images of the solar corona brings
out many subtle details that are easily missed in the intensity
images. Specifically, wavelet processing can enhance the edges on
large and small scales making it easier to detect and define helical
features. We used the processed LASCO images obtained during the
period 1997 -2001 to study the structure and motions of nearly radial
streamers extending from coronal holes adjacent to flaring active
regions. Some of the streamers show outward-propagating twist. These
helical fields extend into the heliosphere where they would reach 1
AU with a path length generally greater than the 1.2 AU of idealized
fields following the Parker spiral. We focused on the regions from our
earlier work (Rust et al., ApJ 687, 635, 2008) on flares associated
with beams of near-relativistic electrons detected at 1 AU with the ACE
spacecraft. Our study shows that the electron beam's typical delay of
about 10 min in arriving at 1 AU may be due to their following a helical
path from Sun to Earth. According to the reconnection jet model, the
helical component may be introduced to open fields by earlier events
involving reconnections with emerging, twisted flux ropes. Our study
implies that the escaping electrons may be accelerated at the same
time as the trapped electrons that produce X-ray flare emissions. NASA supported this work with grant NNG 05GM69G.

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Title: On the plumbing system of volcanic complexes: field constraints
from the Isle of Skye (UK) and FEM elasto-plastic modelling including
gravity and tectonics.
Authors: Bistacchi, A.; Pisterna, R.; Romano, V.; Rust, D.; Tibaldi, A.
2009EGUGA..11.8581B Altcode:
The plumbing system that connects a sub-volcanic magma reservoir to the
surface has been the object of field characterization and mechanical
modelling efforts since the pioneering work by Anderson (1936), who
produced a detailed account of the spectacular Cullin Cone-sheet
Complex (Isle of Skye, UK) and a geometrical and mechanical model
aimed at defining the depth to the magma chamber. Since this work, the
definition of the stress state in the half space comprised between the
magma reservoir and the surface (modelled either as a flat surface or a
surface comprising a volcanic edifice) was considered the key point in
reconstructing dike propagation paths from the magma chamber. In fact,
this process is generally seen as the propagation in an elastic media
of purely tensional joints (mode I or opening mode propagation), which
follow trajectories perpendicular to the least compressive principal
stress axis. Later works generally used different continuum mechanics
methodologies (analytic, BEM, FEM) to solve the problem of a pressure
source (the magma chamber, either a point source or a finite volume)
in an elastic (in some cases heterogeneous) half space (bounded by a
flat topography or topped by a "volcano"). All these models (with a few
limited exceptions) disregard the effect of the regional stress field,
which is caused by tectonic boundary forces and gravitational body load,
and consider only the pressure source represented by the magma chamber
(review in Gudmundsson, 2006). However, this is only a (sometimes
subordinate) component of the total stress field. Grosfils (2007)
first introduced the gravitational load (but not tectonic stresses)
in an elastic model solved with FEM in a 2D axisymmetric half-space,
showing that "failure to incorporate gravitational loading correctly"
affect the calculated stress pattern and many of the predictions
that can be drawn from the models. In this contribution we report on
modelling results that include: 2D axisymmetric or true 3D geometry;
gravitational body load; anisotropic tectonic stresses; different shapes
and depths of the magma chamber; different overpressure levels in the
magma chamber; different shapes of the topographic surface (e.g. flat,
volcano, caldera); linear-elastic or elasto-plastic Drucker-Prager
rheology. The latter point, which in our opinion constitutes a
fundamental improvement in the model, has proven necessary because in a
purely elastic model the stress state would rise at levels that cannot
be sustained by geologic materials. Particularly around and above the
magma chamber, yielding is expected, influencing the stress field in
the remaining modelling domain. The non-linear problem has been solved
with the commercial finite element package Comsol Multiphysics, using
a parametric solver. At the same time, a field structural analysis
of the classical Cuillin Cone-sheet Complex has been performed. This
analysis has shown that four distinct families of cone sheets of
different age do exist. Among these, the sheets with the higher dip
angle range (80-65°) are confirmed as purely tensional joints, but
those with a lower dip angle range (60-40°) are quite often (when
suitable markers are available) associated with a measurable shear
component. Combining these new field observations with mechanical
modelling results, we propose a new interpretation for the Cuillin
Cone Sheet Complex. The plumbing system was composed by both purely
tensional joints and mesoscopic faults with a shear component, produced
in response to the regional stress field perturbed by the magma chamber,
and later passively re-used as magma emplacement conduits. Under this
assumption, the observed geometry of the Cuillin Cone-sheet Complex is
consistent with a relatively shallow magma chamber with a flattened
laccolite shape. The shape of the palaeotopography, now completely
eroded, has also been considered, but is more weakly constrained by
modelling results. References: Anderson E.M., 1936. The dynamics of the
formation of cone-sheets, ring-dykes and cauldron subsidences. Proc R
Soc Edinburgh, 56, 128-157. Grosfils E.B., 2007. Magma reservoir failure
on the terrestrial planets: Assessing the importance of gravitational
loading in simple elastic models. Journal of Volcanology and Geothermal
Research, 166 (2), 47-75. Gudmundsson A. , 2006. How local stresses
control magma-chamber ruptures, dyke injections, and eruptions in
composite volcanoes. Earth Science Reviews, 79 (1), 1-31.

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Title: The Helical Fields of CMEs and the Paths of Near-Relativistic
Electrons into the Heliosphere
Authors: Rust, D. M.; Haggerty, D. K.; Stenborg, G.
2009EGUGA..11.6412R Altcode:
Wavelet processing of the LASCO images of the solar corona brings
out many subtle details that are easily missed in the intensity
images. Specifically, wavelet processing can enhance the edges of
large and small scale structures making it easier to detect and define
motions. We used the processed LASCO images obtained during the period
1998 - 2001, of maximum activity of the last sunspot cycle, to study
the structure and motions of the CME legs and the nearby fields. Many
CMEs show large-scale latitudinal leg displacements that resemble
screw threads leaving the Sun. The helical fields extend into the
heliosphere after, and sometimes before, the associated CME has left
the LASCO C2 field of view. We focused our attention on the CMEs that
were analyzed by Simnett et al., Ap. J. 579, 854, 2002. They linked
those CMEs to beams of near- relativistic electrons detected at 1
AU with the ACE spacecraft. Our study shows that the electron beams'
typical delay of about 10 min in arriving at 1 AU may be due to their
following a longer, helical path from Sun to Earth than the usually
assumed Parker spiral length of 1.2 AU. The study implies that the
escaping electrons may be accelerated at the same time as the trapped
electrons that produce hard X-ray flare emissions. When that is the
case, there is no need to invoke acceleration in the CME fronts.

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Title: On the Solar Origins of Open Magnetic Fields in the Heliosphere
Authors: Rust, David M.; Haggerty, Dennis K.; Georgoulis, Manolis K.;
Sheeley, Neil R.; Wang, Yi-Ming; DeRosa, Marc L.; Schrijver, Carolus J.
2008ApJ...687..635R Altcode:
A combination of heliospheric and solar data was used to identify open
magnetic fields stretching from the lower corona to Earth orbit. 35
near-relativistic electron beams detected at the ACE spacecraft
"labeled" the heliospheric segments of the open fields. An X-ray
flare occurred &lt;20 minutes before injection of the electrons
in 25 events. These flares labeled the solar segment of the open
fields. The flares occurred in western-hemisphere active regions (ARs)
with coronal holes whose polarity agreed with the polarity of the
beam-carrying interplanetary fields in 23 of the 25 events. We conclude
that electron beams reach 1 AU from open AR fields adjacent to flare
sites. The Wang &amp; Sheeley implementation of the potential-field
source-surface model successfully identified the open fields in
36% of cases. Success meant that the open fields reached the source
surface within 3 heliographic deg of the interplanetary magnetic field
connected to ACE at 1 AU. Inclusion of five near misses improves
the success rate to 56%. The success rate for the Schrijver &amp;
DeRosa PFSS implementation was 50%. Our results suggest that, even
if the input magnetic data are updated frequently, the PFSS models
succeed in only ~50% of cases to identify the coronal segment of open
fields. Development of other techniques is in its infancy.

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Title: Probing Open Magnetic Fields at the Sun with near-relativistic
electron beams
Authors: Haggerty, D. K.; Rust, D. M.; Georgoulis, M. K.
2008AGUSMSH43B..06H Altcode:
Processes associated with solar flares accelerate and inject
near-relativistic electrons onto open coronal field lines. Some of
these electron events propagate nearly scatter-free to 1 AU, where their
spectra and angular distributions can be measured. We used a carefully
selected list of electron events for which both the solar and near-Earth
positions are well known. Soft X-ray images from Yohkoh determined the
positions of coronal holes near active regions as well as the flares
associated with the electron events. We chose relatively small events
that exhibit nearly Gaussian shaped time-intensity profiles. These
events should incur minimal coronal and heliospheric transport effects,
which can affect the Sun-to-Earth path length. Twenty-five events
met our criteria for inclusion in the study. We use three different
methods to estimate the path-length of the electrons and two different
potential-field source-surface calculations to trace the open fields
from their intersection with the heliospheric field at 2.5 solar radii
down to the base of the corona. We report on the successes and failures
of these PFSS models to identify open fields in/near active regions
and to indicate correctly which open coronal fields are connected to
the interplanetary magnetic field at Earth.

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Title: Survey of Magnetic Helicity Injection in Regions Producing
X-Class Flares
Authors: LaBonte, B. J.; Georgoulis, M. K.; Rust, D. M.
2007ApJ...671..955L Altcode:
Virtually all X-class flares produce a coronal mass ejection (CME),
and each CME carries magnetic helicity into the heliosphere. Using
magnetograms from the Michelson Doppler Imager on the Solar
and Heliospheric Observatory, we surveyed magnetic helicity
injection into 48 X-flare-producing active regions recorded by
the MDI between 1996 July and 2005 July. Magnetic helicity flux
was calculated according to the method of Chae for the 48 X-flaring
regions and for 345 non-X-flaring regions. Our survey revealed that a
necessary condition for the occurrence of an X-flare is that the peak
helicity flux has a magnitude &gt;6×1036 Mx2
s-1. X-flaring regions also consistently had a higher net
helicity change during the ~6 day measurement intervals than nonflaring
regions. We find that the weak hemispherical preference of helicity
injection, positive in the south and negative in the north, is caused
by the solar differential rotation, but it tends to be obscured by the
intrinsic helicity injection, which is more disorganized and tends to be
of opposite sign. An empirical fit to the data shows that the injected
helicity over the range 1039-10 43 Mx2
s-1 is proportional to magnetic flux squared. Similarly,
over a range of 0.3-3000 days, the time required to generate the
helicity in a CME is inversely proportional to the magnetic flux
squared. Most of the X-flare regions generated the helicity needed
for a CME in a few days to a few hours.

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Title: Quantitative Forecasting of Major Solar Flares
Authors: Georgoulis, Manolis K.; Rust, David M.
2007ApJ...661L.109G Altcode:
We define the effective connected magnetic field, Beff,
a single metric of the flaring potential in solar active regions. We
calculated Beff for 298 active regions (93 X- and M-flaring,
205 nonflaring) as recorded by SOHO/MDI during a 10 yr period covering
much of solar cycle 23. We find that Beff is a robust
criterion for distinguishing flaring from nonflaring regions. A
well-defined 12 hr conditional probability for major flares depends
solely on Beff. This probability exceeds 0.95 for M-class and
X-class flares if Beff&gt;1600 G and Beff&gt;2100
G, respectively, while the maximum calculated Beff-values
are near 4000 G. Active regions do not give M-class and X-class
flares if Beff&lt;200 G and Beff&lt;750 G,
respectively. We conclude that Beff is an efficient
flare-forecasting criterion that can be computed on a timely basis
from readily available data.

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Title: Assessment Of The Eruptive Potential In Solar Active Regions
Authors: Georgoulis, Manolis K.; Rust, D. M.
2007AAS...210.9325G Altcode: 2007BAAS...39Q.215G
Solar active regions involving massive amounts of magnetic flux and
conspicuous polarity inversion lines have always been considered likely
sources of major flares and fast active-region CMEs. We quantify the
magnetic complexity in the photospheric boundary of active regions
and thereafter infer a well-defined 12-24-hour likelihood of major
eruptions. Vector magnetograms are not required for our analysis,
which is validated by application to about 300 active regions observed
by SoHO/MDI over a period of a few to several days each. The proposed
single metric favors a well-defined physical mechanism for major flares
and CMEs and may lead to a detailed, quantitative, understanding of
the flare/CME phenomenon. This work has received partial support by
NASA Grant NNG05-GM47G.

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Title: The Fundamental Role Of Magnetic Helicity In Major Solar
Eruptions
Authors: Rust, David M.; Georgoulis, M. K.
2007AAS...210.2913R Altcode: 2007BAAS...39R.139R
What is the role magnetic helicity plays in solar eruptions? To find
out, we calculate the magnetic helicity flux for 48 X-class flaring
solar active regions and for 345 M-class flaring regions. Each region
was observed over a period of a few, to several, days by SoHO/MDI. We
find consistently higher helicity buildup rates for the X-flaring
regions. X-class flares do not occur if the peak helicity flux is
smaller than 6 x 1036 Mx2/s, with most nonflaring
regions showing much smaller peaks. The weak hemispheric preference of
magnetic helicity is caused by the solar differential rotation,
but it is blurred by the intrinsic helicity injection which is more
disorganized and of opposite sign. Notably, X-flaring regions can
generate the helicity for a typical CME within a few hours to a few
days, contrary to most flare-quiescent regions that require from several
tens to hundreds of days. We conclude that accumulation of magnetic
helicity is a precondition for major flare/CME events. This work has
received partial support by NASA Grants NAG5-13504 and NNG05-GM47G.

---------------------------------------------------------
Title: Obituary: Barry James LaBonte, 1950-2005
Authors: Rust, David Maurice
2006BAAS...38.1277R Altcode:
Dr. Barry J. LaBonte, age 55, a senior solar physicist in the Space
Department of the Johns Hopkins University Applied Physics Laboratory,
died on 24 October 2005 in Philadelphia of complications following
surgery. He was an internationally recognized expert on solar magnetic
fields, the solar cycle, and on the sophisticated instruments needed
for studying them. Barry LaBonte was born in Providence, Rhode
Island on 28 April 1950. His parents were Arlene and William LaBonte,
and Barry was the oldest of their three children. He excelled early in
mathematics and was admitted to the California Institute of Technology,
where he earned a BS in economics and a PhD in astronomy. From 1978
to 1981, he did his postdoctoral work at the Mount Wilson Observatory
where he and Dr. Robert Howard discovered and analyzed the solar
torsional oscillations, which are global flow patterns somewhat
analogous to the jet streams of terrestrial weather. They described
their findings in a series of thirteen papers in three years. LaBonte
and Howard also showed that magnetic fields on the sun are much more
dynamic than were previously thought. Contrary to the impression that
a few, long-lived sunspots give, the total replacement of the surface
magnetic flux occurs within only ten days. In 1981 Barry became an
astronomer at the Institute for Astronomy of the University of Hawaii,
where he taught undergraduate and advanced graduate courses and became
head of the Mees Solar Observatory. In addition to further work on
solar magnetism, he initiated a research program in solar acoustic
oscillations, which led to the discovery that sunspots absorb acoustic
waves of the global oscillations of the sun. Doug Braun, Tom Duvall,
and Barry LaBonte calculated that sunspot magnetic fields, contrary to
earlier expectations, absorb enough p-mode energy to alter the spectrum
of the global oscillations. It was later shown that sensitive analysis
of the oscillations on the face of the sun could detect the presence
of sunspots on the invisible side, before they rotate into view. The
method, called helioseismic acoustic imaging, has led to much improved
two-week predictions of solar activity on the earth-facing side of the
sun. While at the University of Hawaii, he guided the work of graduate
students and postdocs, and many of his students are among today's
outstanding solar researchers. Barry served the AAS Solar Physics
Division variously as a member of the Steering Committee, Nominating
Committee, and the Hale Prize Committee. He served the nation on the
NSF-NASA-DOE Astronomy and Astrophysics Advisory Committee and the
NASA Solar and Heliospheric Physics Management and Operations Working
Group. He worked hard to improve the visibility of heliospheric
physics at NASA, where it encountered a very barren stretch in the
late 1980s and early 1990s. With the initiation of the "Living With a
Star" program in 2000, Barry moved to the East Coast where at the Johns
Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland,
he could work more effectively on solar space missions. Barry felt
at home with all aspects of solar physics, and he found excitement in
the fact that solar and heliospheric science had an impact on earth and
man-made systems. At APL, he worked principally on the interpretation of
solar magnetic activity. He also helped to develop the technology of the
Solar Bolometric Imager, a unique telescope for precise measurements
of the sources of the variations in the sun's radiative output. The
torsional oscillations that LaBonte and Howard discovered may be one
source of subtle and unexplained variations. Barry also was interested
in the flow of magnetic helicity into the corona. He developed a
program to automatically compute from near real-time data the amount of
helicity entering the corona each day. He used the program to compile
helicity data on hundreds of sunspot groups and concluded that there
is a threshold accumulation of helicity needed for the occurrence of a
large flare. His work always involved fundamental science that could
possibly lead to accurate forecasts of solar activity and its effect
on geospace. When he died, he was studying the three-dimensional
structure of the magnetic fields and electric currents in the solar
corona in order to understand the disequilibrium that produces solar
eruptions. I first met Barry when he was a summer intern working
with George Simon at the Sacramento Peak Observatory in Sunspot, New
Mexico in the early 1970s. Besides working on the solar granulation,
Barry learned how to use the Doppler-Zeeman analyzer, the first of
the many solar magnetographs that he used to such advantage in his
productive career. We had common scientific interests, which led me to
follow his career closely, although I was on the East Coast and he was
in Hawaii. We had both done our thesis under Hal Zirin and our postdoc
with Bob Howard and had haunted many of the same scientific meetings,
so I felt I knew him well. At APL he brought a depth of understanding
and quick intelligence to our little solar group that lighted up every
day. Barry was more than an imaginative, witty, and productive
scientist whose contributions greatly advanced solar physics. He was
also a devoted father, rarely taking off from work except to be with
his children. Inspired by his daughter Hillary's decision to train for
an operatic career, he became an opera buff. He was an avid reader of
history, especially military history, and was a member of the Hawaii
Bunny Club and the Howard County Hare Raisers. He is survived by his
wife, Beatrice Hawkins, and by their three children, Allan, Hillary,
and Anna.

---------------------------------------------------------
Title: Mapping Solar Open Magnetic Fields With Near-Relativistic
Electron Beams
Authors: Rust, D. M.; Haggerty, D. K.
2006AGUFMSH11A0367R Altcode:
We used a combination of heliospheric and solar data to identify a
set of open fields for which both the solar and near-Earth positions
are known. The purpose is to test existing and developing models of
magnetic field topology. The models are provided by other members of
the Living With a Star Targeted Research &amp; Technology Heliospheric
Magnetic Field Focus Team. For our part, we concentrated on the solar
phenomena associated with near-relativistic electron energization and
transport, because near-relativistic electrons emit or excite many
forms of detectable electromagnetic (EM) radiation. The EM radiations
help us identify the solar end or `origin' of individual open field
lines, and the near-Earth ends can be identified by their association
with electron beam events at 1 AU, using the EPAM instrument on the
ACE spacecraft. The total number of events that met our criteria
for inclusion in the study is about 200. For each event, we used the
measured solar wind speed to estimate the curvature of the field line,
from which we could infer the Carrington longitude of the open field on
the `source surface' at 2.5 solar radii. Potential field source surface
calculations supplied by I.-M. Wang and N. R. Sheeley allowed us to
trace the open fields from their intersection with the heliospheric
field at 2.5 solar radii down to the base of the corona. Our study
was specifically designed to test two contrasting open field models:
(1) a model with widely distributed open fields and (2) a model with
open fields only in well- defined coronal holes. We will present the
preliminary results of the study and several case studies. This work
was supported by NASA TR&amp;T grant NNG05GM69G.

---------------------------------------------------------
Title: Narrow-band Filter Observations of the Red-Line Corona at
the 29 March 2006 Eclipse
Authors: Rust, David M.; Noble, M. W.; Pasachoff, J. M.; Babcock,
B. A.; Bruck, M. A.; Wittenmyer, R. A.
2006SPD....37.0110R Altcode: 2006BAAS...38..217R
We report on observations of the corona above active region NOAA 10866,
which was on the solar east limb at S 06 on 29 March 2006. Filtergrams
were obtained at six 0.22 Å steps across the profile of the Fe
X line at 6374.5 Å during the total solar eclipse, starting at
about 1052 UT. The telescope was a 35-cm Schmidt-Cassegrain Meade
RCX400 with the solar image relayed to a 512 x 512-pixel Andor Ixon
DV887 CCD camera via telecentric optics and two narrow-bandpass
filters: (1) a 2 Å thin-film Andover Corp. blocker and (2) a 0.16
Å tunable Fabry-Perot etalon, made by the CSIRO Australian Centre
for Precision Optics. The F-P etalon is a Y-cut lithium niobate wafer
of 0.200-mm thickness coated with reflective and conductive thin-film
layers. Application of a voltage to the etalon produces a passband shift
of 0.0011 Å/volt. Calibration at the eclipse site in Kastellorizo,
Greece, was maintained by reference to a WSTech thermo-electrically
stabilized diode laser tuned to 6375.16 Å. The profile and Doppler
shifts of the Fe X line will be discussed.The expedition was supported
by NSF (ATM-0552116), the Committee for Research and Exploration of
the National Geographic Society, NASA's Planetary Astronomy Division
for the CCD cameras (NNG04GE48G), Sigma Xi, and the Rob Spring Fund
and the Ryan Patrick Gaishin Fund at Williams College.

---------------------------------------------------------
Title: Probing Solar Open Magnetic Fields With Near-relativistic
Electron Beams.
Authors: Haggerty, Dennis K.; Rust, D.; Sheeley, N. R.; Wang, Y.
2006SPD....37.1102H Altcode: 2006BAAS...38R.238H
To achieve better understanding of our Sun-Earth environment,
NASA's Living with a Star (LWS) program addresses question that
cut across discipline boundaries. We present preliminary results on
probing solar open magnetic fields with near-relativistic electron
beams. This effort is directed at the major question: What determines
the topology and evolution of the magnetic fields that stretch from the
surface of the Sun to the outer boundary of the heliosphere? During
nine years of operation, nearly an entire solar cycle, the ACE/EPAM
instrument has measured well over 600 near-relativistic electron
events. Approximately 30% of these electron events are impulsive
with beam-like anisotropies and are predominantly from flares on the
western hemisphere. Near-relativistic electrons are accelerated in the
low corona and are released onto open coronal field lines, where they
propagate nearly scatter-free out to 1 AU. Near-relativistic electrons
are ideal probes of coronal open field lines because the transit time
to 1 AU is 10 minutes as compared to lower energy ions that spend more
time in the interplanetary medium and are therefore much more subject
to transport processes. In this work we use observations of electrons
from 1 AU, observations of various electromagnetic emissions associated
with electron acceleration at the Sun, and observations and models
of open magnetic field lines at the Sun to pinpoint the location of
electron acceleration.

---------------------------------------------------------
Title: Coronal Observations at the 29 March 2006 Total Solar Eclipse
Authors: Pasachoff, J. M.; Babcock, B. A.; Souza, S. P.; Bruck, M. A.;
Hess, P. W.; Kimmel, S. B.; Levitt, J. S.; Steele, A. S.; Tsykalova,
A. E.; Rust, D. M.; Noble, M. W.; Wittenmyer, R.; Kern, J.; Hawkins,
R. L.; Seiradakis, J. H.; Voulgaris, A.; Pistikoudis, G.; Nestoras,
J.; Demianski, M.
2006SPD....37.0107P Altcode: 2006BAAS...38Q.216P
We report on our eclipse expedition to Kastellorizo, Greece, in the
Dodecanese off the Turkish coast. We observed 3 min 00 sec of totality
on 29 March 2006. All our observations worked very well. One of them
was high-time-resolution (10 Hz) observations in the coronal green
line looking at coronal loops; another was similar observations in
the coronal red line; both are to determine among theories of coronal
heating and continue earlier reports of excess Fourier power in the 1
Hz range. As we knew from SOHO observations from the day before the
eclipse, an active region was stationed right on the east limb and
it gave us very suitable loops to study, with pointing in agreement
with TRACE. A third set of observations used a very narrow-band filter
(Fabry-Perot), with 1/6 angstrom resolution, to make velocity (Doppler)
images of the same coronal loops. A fourth set of observations used a
telescope we had built to match the size of the now defunct innermost
coronagraph on the NASA/ESA SOHO, and it indeed was used to merge with
SOHO EIT disk coronal images and SOHO LASCO outer coronal coronagraph
images. Further, radial-filter "Newkirk camera" images captured
the role of magnetic fields in shaping coronal streamers, which we
also display in mergers of images with sequential exposure times. The expedition was supported by NSF (ATM-0552116), the Committee
for Research and Exploration of the National Geographic Society,
NASA's Planetary Astronomy Division for the CCD cameras (NNG04GE48G),
Sigma Xi, and the Rob Spring Fund and the Ryan Patrick Gaishin Fund
at Williams College.

---------------------------------------------------------
Title: Emergence of undulatory magnetic flux tubes by small scale
reconnections
Authors: Pariat, E.; Aulanier, G.; Schmieder, B.; Georgoulis, M. K.;
Rust, D. M.; Bernasconi, P. N.
2006AdSpR..38..902P Altcode:
With Flare Genesis Experiment (FGE), a balloon borne observatory
launched in Antarctica on January 2000, series of high spatial
resolution vector magnetograms, Dopplergrams, and Hα filtergrams
have been obtained in an emerging active region (AR 8844). Previous
analyses of this data revealed the occurence of many short-lived
and small-scale H α brightenings called 'Ellerman bombs'
(EBs) within the AR. We performed an extrapolation of the field above
the photosphere using the linear force-free field approximation. The
analysis of the magnetic topology reveals a close connexion between
the loci of EBs and the existence of "Bald patches" (BP) regions
(BPs are regions where the vector magnetic field is tangential to
the photosphere). Some of these EBs/BPs are magnetically connected
by low-lying field lines, presenting a serpentine shape. This results
leads us to conjecture that arch filament systems and active regions
coronal loops do not result from the smooth emergence of large scale
Ω-loops, but rather from the rise of flat undulatory flux tubes which
get released from their photospheric anchorage by reconnection at BPs,
which observational signature is Ellerman bombs.

---------------------------------------------------------
Title: Observation of Small Scale Reconnection Role in Undulated
Flux Tube Emergence
Authors: Pariat, E.; Aulanier, G.; Schmieder, B.; Georgoulis, M. K.;
Rust, D. M.; Bernasconi, P. N.
2005ESASP.596E..34P Altcode: 2005ccmf.confE..34P
No abstract at ADS

---------------------------------------------------------
Title: The Sun and the Heliosphere as an Integrated System
Authors: Rust, David M.
2005EOSTr..86..386R Altcode:
The heliosphere is a bay in the interstellar space around the Sun where
the solar wind blows lustily and holds back the magnetic fields and
plasma of the local interstellar cloud. According to recent measurements
from the Voyager 1 spacecraft, the radius of this bay, which is where
the solar wind ceases to be supersonic, is about 94 astronomical units
(AU) (1 AU = distance from the Sun to Earth). Much of what happens
at the outer edges of the heliosphere is determined by what happens
on the Sun. Magnetic fields generated in the solar interior boil to
the surface and emerge into the outer atmosphere, called the corona,
where they destabilize and propel coronal mass ejections (CMEs) into
the heliosphere. The corona is also the source of the solar wind.

---------------------------------------------------------
Title: Advanced Automated Solar Filament Detection And
Characterization Code: Description, Performance, And Results
Authors: Bernasconi, Pietro N.; Rust, David M.; Hakim, Daniel
2005SoPh..228...97B Altcode:
We present a code for automated detection, classification, and tracking
of solar filaments in full-disk Hα images that can contribute
to Living With a Star science investigations and space weather
forecasting. The program can reliably identify filaments; determine
their chirality and other relevant parameters like filament area,
length, and average orientation with respect to the equator. It is
also capable of tracking the day-by-day evolution of filaments while
they travel across the visible disk. The code was tested by analyzing
daily Hα images taken at the Big Bear Solar Observatory from mid-2000
until beginning of 2005. It identified and established the chirality
of thousands of filaments without human intervention. We compared
the results with a list of filament proprieties manually compiled by
Pevtsov, Balasubramaniam and Rogers (2003) over the same period of
time. The computer list matches Pevtsov's list with a 72% accuracy. The
code results confirm the hemispheric chirality rule stating that dextral
filaments predominate in the north and sinistral ones predominate in the
south. The main difference between the two lists is that the code finds
significantly more filaments without an identifiable chirality. This may
be due to a tendency of human operators to be biased, thereby assigning
a chirality in less clear cases, while the code is totally unbiased. We
also have found evidence that filaments obeying the chirality rule
tend to be larger and last longer than the ones that do not follow the
hemispherical rule. Filaments adhering to the hemispheric rule also tend
to be more tilted toward the equator between latitudes 10∘
and 30∘, than the ones that do not.

---------------------------------------------------------
Title: Observational Evidence of the Kink Instability In Solar
Eruptions
Authors: Rust, D. M.
2005AGUSMSH54B..02R Altcode:
Two approaches to studying the role of source region magnetic fields
for CMEs are described. First, observational evidence is used to infer
that the MHD helical kink instability is associated with at least some
filament eruptions and CMEs. In seven cases, the sense of twist and
writhe in the source regions were determined from movies of erupting
filaments. In every case the sense of twist was the same as the sense
of writhe, as required for a kink. Next, we consider six different
cases in which the chirality and axis orientation of interplanetary
flux ropes could be compared with the corresponding signatures in the
source regions at the Sun. In four cases, the chirality and orientation
inferred from these pre-eruption flux rope signatures agreed well with
the interplanetary flux rope signatures. In two cases, the flux rope
axis orientations differed by about 150 degrees. These results suggest
that the flux ropes existed prior to eruption, that they become flux
ropes in interplanetary space, and, at least in some cases, that the
kink instability is the likely cause of eruption.

---------------------------------------------------------
Title: Comparison of Interplanetary Disturbances at the NEAR
Spacecraft with Coronal Mass Ejections at the Sun
Authors: Rust, D. M.; Anderson, B. J.; Andrews, M. D.; Acuña, M. H.;
Russell, C. T.; Schuck, P. W.; Mulligan, T.
2005ApJ...621..524R Altcode:
We examined interplanetary (IP) magnetic field disturbances recorded by
the Near Earth Asteroid Rendezvous-Shoemaker spacecraft (NEAR) when it
was above either the east or west solar limb as seen from Earth; we then
identified the associated coronal mass ejections (CMEs) detected above
the limbs by the SOHO LASCO coronagraph. We found 10 cases in which
a nonrecurring IP disturbance could be associated with a CME. Eight
of the disturbances included a magnetic flux rope signature. Flux rope
chirality and axis orientation were determined for each one and compared
with chirality and axis orientation at the Sun, as inferred from flux
rope signatures-filaments and sigmoids-that could be associated with
the CMEs. In most cases, the chirality and orientation inferred from
these preeruption flux rope signatures agreed well with the flux rope
signatures at NEAR. These results suggest, in agreement with Plunkett
and coworkers, that the flux ropes existed prior to eruption and that
the flux ropes on the Sun become flux ropes in IP space. Comparisons of
the CME speeds to the time-of-flight average speeds showed that flux
ropes are less accelerated or decelerated by the solar wind than are
the CME leading edges. These results imply that the faint features or
loops that make up the CME leading edges are probably distinct from
the flux ropes.

---------------------------------------------------------
Title: Observational Evidence of the Kink Instability in Solar
Filament Eruptions and Sigmoids
Authors: Rust, D. M.; LaBonte, B. J.
2005ApJ...622L..69R Altcode:
Two lines of observational evidence are used to infer that the MHD
helical kink instability is associated with solar eruptions. The
senses of twist and writhe are determined in images of seven erupting
filaments obtained at 10830, 1600, 195, and 171 Å. In every case the
sense of twist is the same as the sense of writhe, as required for
a kink. From images in the soft X-ray and EUV spectrum, measurements
of the height/width ratio of 623 sigmoids show a mean value of 5.47,
which is the ratio expected for kinked flux ropes.

---------------------------------------------------------
Title: Finding the sources of irradiance variation at sunspot
minimum .
Authors: Bernasconi, P. N.; Foukal, P.; Rust, D. M.; LaBonte, B. J.
2005MmSAI..76..907B Altcode:
In 2006-2007 the Solar Bolometric Imager (SBI) will operate in the polar
stratosphere where near-space conditions can be attained for 10 to 30
days. The instrument will provide bolometric (wavelength-integrated
light) and color temperature images of the Sun. At the upcoming sunspot
minimum, SBI observations will be able to detect subtle sources
of solar irradiance variation with the least confusion by signals
from the magnetic fields. This is the best observational approach
to characterizing potential causes of the long-term irradiance
variations. Possible predicted sources of secular variability
include torsional waves and meridional flow variations. SBI uses a
30-cm diameter F/12 Dall-Kirkham telescope with uncoated mirrors, and
neutral density filters to provide broadband (bolometric) sensitivity
that varies only by ±7% over the wavelengths from 0.31 mu m to 2.6
mu m. Inferred solar irradiance variations will be compared with space
based full-disk radiometric measurements.

---------------------------------------------------------
Title: Transport of Magnetic Helicity and Dynamics of Solar Active
Regions
Authors: Georgoulis, M. K.; Labonte, B. J.; Rust, D. M.
2005HiA....13..117G Altcode:
We outline a simple method to monitor variations of the magnetic
helicity the current helicity and the non-potential (free) magnetic
energy on the photospheric boundary of solar active regions. Explicit
manifestations of dynamical activity in the solar atmosphere such as
flares coronal mass ejections and filament eruptions may be related to
these variations. While similar methods require knowledge of the vector
potential and the velocity field vector on the photosphere our method
requires only the photospheric potential magnetic field corresponding
to the observed magnetograms. The calculation of the potential field
for any given magnetogram is straightforward. Moreover our method
relies on the constant-alpha force-free approximation assumed to hold
in the active region. Whether the above is a realistic assumption
can be tested using an array of well-documented methods. Therefore
our technique may prove quite useful to at least a subset of active
regions in which the linear force-free approximation is justifiable.

---------------------------------------------------------
Title: Magnetic Helicity in Sigmoids, Coronal Mass Ejections and
Magnetic Clouds
Authors: Rust, D. M.
2005HiA....13..105R Altcode:
Filaments coronal mass ejections (CMEs) and magnetic clouds (MCs) all
show signatures of twisted and writhing magnetic fields. CMEs are often
associated with MCs whose fields are regularly probed with sensitive
magnetometers. These measurements reveal that MC fields are helical
and each cloud carries magnetic helicity away from the sun. It is more
difficult to determine the helicity of the corresponding features -
filaments and coronal structures - on the sun. This talk will survey
helicity estimates of solar features including their hemispherical
distributions and evidence for writhe and twist in the fields. The
distribution of magnetic helicity in the solar atmosphere may provide
important clues to the workings of the solar dynamo.

---------------------------------------------------------
Title: Finding the Sources of Irradiance Variation at Sunspot Minimum
Authors: Rust, D. M.; Bernasconi, P. N.; Foukal, P. V.; Labonte, B. J.
2004AGUFMSH51E..02R Altcode:
In 2006-2007 the Solar Bolometric Imager (SBI) and the Multi-Spectral
Imager (MSI) will operate in the polar stratosphere where near-space
conditions can be attained for 10 to 20 days. The instruments will
provide bolometric (wavelength-integrated light) and color temperature
images of the Sun. At the upcoming sunspot minimum, SBI observations
will be able to detect subtle sources of solar irradiance variation
with the least confusion by signals from the magnetic fields. This is
the best observational approach to characterizing potential causes
of the long-term irradiance variations. Possible predicted sources
of secular variability include torsional waves and meridional flow
variations. SBI uses a 30-cm diameter F/12 Dall-Kirkham telescope with
uncoated mirrors, and neutral density filters to provide broadband
(bolometric) sensitivity that varies only by ±7 percent over the
wavelengths from 0.28 microns to 2.6 microns. The MSI is a CCD-based
imager that will provide diagnostics of solar magnetic and thermal
structures while SBI assesses their radiance. Sunspots, faculae
and magnetic network will be identified from the MSI images. Sonic
filtering of the MSI images will isolate the oscillatory signal. That
signal will be used to remove oscillations from SBI averages to reduce
the solar noise. Inferred solar irradiance variations will be compared
with SORCE/TIM and ACRIMSAT measurements. The images and data products
will be openly available via the Web.

---------------------------------------------------------
Title: An Integrated Program to Forecast Geostorms
Authors: Labonte, B. J.; Rust, D.; Bernasconi, P.; Georgoulis, M.
2004AGUFMSA51B0243L Altcode:
We have developed several operational products and automated tools for
assessing the helicity content of solar regions and their probability of
launching a geoeffective coronal mass ejection. These include detection
of active region sigmoids, measurement of magnetic helicity injection
in active regions, measurement of the sense of helicity in solar
filaments, and the estimate of magnetic helicity content of active
regions from vector magnetogram observations. In this presentation
we discuss a new program to integrate the separate products and tools
into a single product that provides a quantitative mid-term forecast
of solar activity that results in geomagnetic storms.

---------------------------------------------------------
Title: Advanced Automated Solar Filament Detection and
Characterization Code: Description, Performance, and Results
Authors: Bernasconi, P. N.; Rust, D. M.
2004AGUFMSA51B0235B Altcode:
We have developed a code for automated detection and classification
of solar filaments in full-disk H-alpha images that can contribute
to Living With a Star science investigations and space weather
forecasting. The program can reliably identify filaments, determine
their chirality and other relevant parameters like the filaments
area and their average orientation with respect to the equator, and
is capable of tracking the day-by-day evolution of filaments while
they travel across the visible disk. Detecting the filaments when they
appear and tracking their evolution can provide not only early warnings
of potentially hazardous conditions but also improve our understanding
of solar filaments and their implications for space weather at 1 AU. The
code was recently tested by analyzing daily H-alpha images taken at the
Big Bear Solar Observatory during a period of four years (from mid 2000
until mid 2004). It identified and established the chirality of more
than 5000 filaments without human intervention. We compared the results
with the filament list manually compiled by Pevtsov et al. (2003)
over the same period of time. The computer list matches the Pevtsov
et al. list fairly well. The code results confirm the hemispherical
chirality rule: dextral filaments predominate in the north and sinistral
ones predominate in the south. The main difference between the two
lists is that the code finds significantly more filaments without
an identifiable chirality. This may be due to a tendency of human
operators to be biased, thereby assigning a chirality in less clear
cases, while the code is totally unbiased. We also have found evidence
that filaments with definite chirality tend to be larger and last longer
than the ones without a clear chirality signature. We will describe the
major code characteristics and present and discuss the tests results.

---------------------------------------------------------
Title: Resistive Emergence of Undulatory Flux Tubes
Authors: Pariat, E.; Aulanier, G.; Schmieder, B.; Georgoulis, M. K.;
Rust, D. M.; Bernasconi, P. N.
2004ApJ...614.1099P Altcode:
During its 2000 January flight, the Flare Genesis Experiment observed
the gradual emergence of a bipolar active region, by recording a series
of high-resolution photospheric vector magnetograms and images in the
blue wing of the Hα line. Previous analyses of these data revealed the
occurrence of many small-scale, transient Hα brightenings identified
as Ellerman bombs (EBs). They occur during the flux emergence,
and many of them are located near moving magnetic dipoles in which
the vector magnetic field is nearly tangential to the photosphere. A
linear force-free field extrapolation of one of the magnetograms was
performed to study the magnetic topology of small-scale EBs and their
possible role in the flux emergence process. We found that 23 out of 47
EBs are cospatial with bald patches (BPs), while 15 are located at the
footpoints of very flat separatrix field lines passing through distant
BPs. We conclude that EBs can be due to magnetic reconnection, not only
at BP locations, but also along their separatrices, occurring in the
low chromosphere. The topological analysis reveals, for the first time,
that many EBs and BPs are linked by a hierarchy of elongated flux tubes
showing aperiodic spatial undulations, whose wavelengths are typically
above the threshold of the Parker instability. These findings suggest
that arch filament systems and coronal loops do not result from the
smooth emergence of large-scale Ω-loops from below the photosphere,
but rather from the rise of undulatory flux tubes whose upper parts
emerge because of the Parker instability and whose dipped lower parts
emerge because of magnetic reconnection. EBs are then the signature
of this resistive emergence of undulatory flux tubes.

---------------------------------------------------------
Title: Broadband Measurements of Facular Photometric Contrast Using
the Solar Bolometric Imager
Authors: Foukal, Peter; Bernasconi, Pietro; Eaton, Harry; Rust, David
2004ApJ...611L..57F Altcode:
We present the first photometric measurements of solar faculae in
broadband light. Our measurements were made during the recent flight of
the Solar Bolometric Imager (SBI), a 30 cm balloon-borne telescope that
imaged the Sun with a spectrally constant response between about 0.31
and 2.6 μm. Our curve of facular contrast versus limb distance agrees
well with values obtained by the blackbody correction of monochromatic
measurements. This decreases uncertainty in the facular irradiance
contribution, which limits searches for other possible mechanisms of
solar luminosity variation, besides changes of photospheric magnetism.

---------------------------------------------------------
Title: Emerging Flux and the Heating of Coronal Loops
Authors: Schmieder, B.; Rust, D. M.; Georgoulis, M. K.; Démoulin,
P.; Bernasconi, P. N.
2004ApJ...601..530S Altcode:
We use data collected by a multiwavelength campaign of observations
to describe how the fragmented, asymmetric emergence of magnetic flux
in NOAA active region 8844 triggers the dynamics in the active-region
atmosphere. Observations of various instruments on board Yohkoh, SOHO,
and TRACE complement high-resolution observations of the balloon-borne
Flare Genesis Experiment obtained on 2000 January 25. We find that
coronal loops appeared and evolved rapidly ~6+/-2 hr after the first
detection of emerging magnetic flux. In the low chromosphere, flux
emergence resulted in intense Ellerman bomb activity. Besides the
chromosphere, we find that Ellerman bombs may also heat the transition
region, which showed “moss” ~100% brighter in areas with Ellerman
bombs as compared to areas without Ellerman bombs. In the corona,
we find a spatiotemporal anticorrelation between the soft X-ray (SXT)
and the extreme ultraviolet (TRACE) loops. First, SXT loops preceded
the appearance of the TRACE loops by 30-40 minutes. Second, the TRACE
and SXT loops had different shapes and different footpoints. Third,
the SXT loops were longer and higher than the TRACE loops. We conclude
that the TRACE and the SXT loops were formed independently. TRACE loops
were mainly heated at their footpoints, while SXT loops brightened in
response to coronal magnetic reconnection. In summary, we observed a
variety of coupled activity, from the photosphere to the active-region
corona. Links between different aspects of this activity lead to
a unified picture of the evolution and the energy release in the
active region.

---------------------------------------------------------
Title: Emerging Flux and the Heating of Coronal Loops
Authors: Schmieder, B.; Démoulin, P.; Rust, D. M.; Georgoulis, M. K.;
Bernasconi, P. N.
2004IAUS..219..483S Altcode: 2003IAUS..219E..18S
We suggest that coronal loop heating is caused by dissipation of
magnetic energy as new magnetic flux emerges from the photosphere. Based
on data from a multi wavelength campaign of observations during the
flight of the Flare Genesis Experiment we describe how emergence
of flux from the photosphere appears directly to heat the corona
to 2-3 MK. Following intense heating the loops cool and become
visible through the filters of the TRACE (Transition Region and
Coronal Explorer)instrument at one million degrees. We determine the
relaxation time of the cooling and compare it withtheoretical heating
functions. The proposed mechanism is well accepted in flare loops but
we suggest that the mechanism is generally valid and helps to explain
the visibility of active region loops in transition region lines.

---------------------------------------------------------
Title: The solar bolometric imager
Authors: Bernasconi, P. N.; Eaton, H. A. C.; Foukal, P.; Rust, D. M.
2004AdSpR..33.1746B Altcode:
The balloon-borne Solar Bolometric Imager (SBI) will provide the first
bolometric (integrated light) maps of the solar photosphere. It will
evaluate the photometric contribution of magnetic structures more
accurately than has been possible with spectrally selective imaging
over restricted wavebands. More accurate removal of the magnetic
feature contribution will enable us to determine if solar irradiance
variation mechanisms exist other than the effects of photospheric
magnetism. The SBI detector is an array of 320 × 240 ferro-electric
thermal IR elements whose spectral absorptance has been extended and
flattened by a deposited layer of gold-black. The telescope itself is
a 30-cm Dall-Kirkham design with uncoated primary and secondary pyrex
mirrors. The combination of telescope and bolometric array provides
an image of the Sun with a flat spectral response between 0.28 and 2.6
μm, over a field of view of 917 × 687 arcsec, and a pixel size of 2.8
arcsec. After a successful set of ground-based tests, the instrument is
being readied for a one-day stratospheric balloon flight that will take
place in September 2003. The observing platform will be the gondola
previously used for the Flare Genesis Experiment (FGE), retrofitted
to house and control the SBI telescope and detector. The balloon
flight will enable SBI to image over essentially the full spectral
range accepted by non-imaging space-borne radiometers such as ACRIM,
making the data sets complementary. The SBI flight will also provide
important engineering data to validate the space worthiness of the
novel gold-blackened thermal array detectors, and verify the thermal
performance of the SBI's uncoated optics in a vacuum environment.

---------------------------------------------------------
Title: Emergence of undulatory magnetic flux tubes by small scale
reconnections
Authors: Pariat, E.; Aulanier, G.; Schmieder, B.; Georgoulis, M. K.;
Rust, D. M.; Bernasconi, P. N.
2004cosp...35.1482P Altcode: 2004cosp.meet.1482P
With Flare Genesis Experiment (FGE), a balloon borne observatory
launched in Antarctica on January 2000, series of high spatial
resolution vector magnetograms, Dopplergrams, and Hα filtergrams
have been obtained in an emerging active region (AR 8844). Previous
analyses of this data revealed the occurence of many short-lived and
small-scale Hα brightenings called 'Ellerman bombs' (EBs) within the
AR. We performed an extrapolation of the field above the photosphere
using the linear force-free field approximation. The analysis of the
magnetic topology reveals a close connexion between the loci of EBs
and the existence of “Bald patches” regions (BPs are regions where
the vector magnetic field is tangential to the photosphere). Among
47 identified EBs, we found that 23 are co-spatial with a BP, while
19 are located at the footpoint of very flat separatrix field lines
passing throught a distant BP. We reveal for the first time that
some of these EBs/BPs are magneticaly connected by low-lying lines,
presenting a 'sea-serpent' shape. This results leads us to conjecture
that arch filament systems and active regions coronal loops do not
result from the smooth emergence of large scale Ω loops, but rather
from the rise of flat undulatory flux tubes which get released from
their photospheric anchorage by reconnection at BPs, whose observational
signature is Ellerman bombs.

---------------------------------------------------------
Title: Lorentz Forces and Helicity Diagnostics in Solar Active
Regions Based on a Fast Resolution of the Azimuthal Ambiguity in
Solar Vector Magnetograms
Authors: Georgoulis, Manolis K.; Labonte, Barry J.; Rust, David M.
2004hell.conf...82G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: First Results Of The Solar Bolometric Imager
Authors: Bernasconi, P. N.; Foukal, P.; Eaton, H. H.; Rust, D. M.
2003AGUFMSH32A1101B Altcode:
On September 1 2003, the Solar Bolometric Imager (SBI) successfully
observed the Sun for several hours while suspended from a balloon in the
stratosphere above New Mexico. The SBI represents a totally new approach
in finding the sources of the solar irradiance variation. The mission
provided the first bolometric (integrated light) maps of the solar
photosphere, that will allow to evaluate the photometric contribution
of magnetic structures more accurately than has been achievable with
spectrally selective imaging over restricted wavebands. The more
accurate removal of the magnetic features contribution will enable
us to determine if solar irradiance variation mechanisms exist other
than the effects of photospheric magnetism. The SBI detector was an
array of 320 x 240 thermal IR elements whose spectral absorptance has
been extended and flattened by a deposited layer of gold-black. The
telescope was a 30-cm Dall-Kirkham with uncoated primary and secondary
pyrex mirrors. The combination of telescope and bolometric array
provided an image of the Sun with a flat spectral response between
0.28 and 2.6 microns, over a field of view of 917 x 687 arcsec with
a pixel size of 2.8 arcsec. The observing platform was the gondola
previously used for the Flare Genesis Experiment (FGE), retrofitted to
house and control the SBI telescope and detector. During the 9 hours
of flight the SBI gathered several thousand bolometric images that
are now being processed to produce the first maps of the total solar
irradiance. The SBI flight is also providing important engineering data
to validate the space worthiness of the novel gold-blackened thermal
array detectors, and to verify the thermal performance of the SBI's
uncoated optics in a vacuum environment. In this paper we will briefly
describe the characteristics of the SBI, its in flight performance,
and we will present the first results of the analysis of the bolometric
images. This work was funded by NASA under grant# NAG5-10998.

---------------------------------------------------------
Title: Measuring Magnetic Helicity Transport in Solar Active Regions:
a Practical Implementation
Authors: Rust, D. M.; Labonte, B. J.
2003AGUFMSH51A..02R Altcode:
The causes of solar eruptions are not well understood, but it is clear
that the emergence of magnetic flux and the accumulation of twisted
(helical) magnetic fields in the solar atmosphere are preconditions
for eruption. It has been very difficult to study these indicators
because the magnetic data were unreliable due to varying `seeing'
conditions. However, SOHO produces reliable magnetograms every 95
minutes. Chae (Astrophys. J. 560, L95, 2001) showed how SOHO (Solar and
Heliospheric Observatory) data can yield reliable estimates of magnetic
flux and magnetic helicity accumulation in the solar atmosphere. Chae's
results suggest that regular time-series analyses of magnetograms could
provide a useful early indicator of the build up of energy in the
solar corona. Our objective has been to develop simple quantitative
indicators of pre-eruption build-up and thereby warn of potential
space weather related disturbances in space systems. We use the SOHO
data, but in the near future the Solar B and SDO missions will provide
much better magnetograms. So far, we have used Chae's method to map
helicity transport in several regions with solar flares. We will show
how advective helicity transport influences flare rate. We will also
compare our results with analyses of vector magnetograms, which show
both advective and convective helicity transport.

---------------------------------------------------------
Title: An Automated System for Detecting Sigmoids in Solar X-ray
Images
Authors: LaBonte, B. J.; Rust, D. M.; Bernasconi, P. N.
2003SPD....34.0504L Altcode: 2003BAAS...35R.814L
The probability of a coronal mass ejection (CME) occurring is linked
to the appearance of structures, called sigmoids, in satellite X-ray
images of the sun. By examination of near real time images, we can
detect sigmoids visually and estimate the probability of a CME and
the probability that it will cause a major geomagnetic storm. We
have devised a pattern recognition system to detect the sigmoids in
Yohkoh SXT and GOES SXI X-ray images automatically. When implemented
in a near real time environment, this system should allow long term,
3 - 7 day, forecasts of CMEs and their potential for causing major
geomagnetic storms.

---------------------------------------------------------
Title: Evidence for Flux Ropes in the Solar Corona
Authors: Rust, D. M.
2003SPD....34.0415R Altcode: 2003BAAS...35..813R
Although twisted magnetic flux ropes are clearly ejected from the Sun,
as demonstrated by LASCO and EIT movies of erupting prominences, there
has been some controversy about whether flux ropes exist in the corona
before ejection. It has been argued that they are formed only upon
ejection. The issue is important because of the need to understand
how eruptions are initiated. Now a clearer picture of solar flux
ropes is emerging with recent high-resolution observations of solar
filaments. Filament's twist and writhe are frequently detectable
even when they do not escape the Sun. The observations of November
1, 2001 and May 27, 2002 made by the TRACE solar telescope both
appear to show the sudden eruption without ejection of a filament,
with transformation of some internal twist into a writhe of approx. +
1. Since magnetic helicity is approximately conserved, even in these
rapid events, it follows that these kink events are strong evidence
that flux ropes are present in the corona. We suggest that a flux
rope may undergo several kink instabilities before it is ejected from
the Sun. We identify coronal X-ray sigmoids as the aftermath of these
sudden kink events. NASA supported this work under grant NAG5-11584.

---------------------------------------------------------
Title: The Solar Bolometric Imager: Characteristics and Performance.
Authors: Bernasconi, P. N.; Foukal, P.; Rust, D. M.
2003SPD....34.2002B Altcode: 2003BAAS...35..844B
The Solar Bolometric Imager (SBI) is an innovative solar telescope
capable of recording the first bolometric (integrated light) maps of the
photosphere. It will enable evaluation of the photometric contribution
of magnetic structures more accurately than has been achievable with
spectrally selective imaging. The SBI has an angular resolution of 5",
sufficient to distinguish sunspots, faculae and enhanced network. These
photospheric magnetic structures are known to be linked closely to
irradiance variations. Accurate removal of irradiance variations linked
to the magnetic features will enable us to determine if other solar
irradiance variation mechanisms exist. The SBI detector is an
array of 320 x 240 ferro-electric thermal IR elements whose spectral
absorptance has been extended and flattened by a deposited layer of
gold-black. The telescope is a 30-cm Dall-Kirkham design with uncoated
primary and secondary pyrex mirrors. The combination of telescope and
bolometric array provides an image of the sun with a flat spectral
response between 0.28 microns and 2.6 microns, over a field of view
of 917" x 687", and a pixel size of 2.8". After completion of ground
tests, the balloon-borne instrument will make a one-day stratospheric
flight in September 2003. Observing from an altitude of over 30
km, the SBI will image the sun over nearly the full spectral range
accepted by non-imaging satellite-borne radiometers such as ACRIM,
making the data sets complementary. The SBI flight will also provide
important engineering data to validate the space worthiness of the
novel gold-blackened thermal array detectors, and to verify the
thermal performance of the SBI's optics in a vacuum environment. Here we will describe the SBI in more detail and present the results
of various instrument performance tests, including solar observations
from the ground, in preparation for the balloon flight. This work
is funded by NASA under grant NAG5-10998.

---------------------------------------------------------
Title: Magnetic Helicity Pumping by Twisted Flux Tube Expansion
Authors: Chae, Jongchul; Moon, Y. -J.; Rust, D. M.; Wang, Haimin;
Goode, Philip R.
2003JKAS...36...33C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Near-infrared chromospheric observatory
Authors: Labonte, Barry; Rust, David M.; Bernasconi, Pietro N.;
Georgoulis, Manolis K.; Fox, Nicola J.; Kalkofen, Wolfgang; Lin,
Haosheng
2003SPIE.4853..140L Altcode:
NICO, the Near Infrared Chromosphere Observatory, is a platform for
determining the magnetic structure and fources of heating for the
solar chromosphere. NICO, a balloon-borne observatory, will use the
largest solar telescope flying to map the magnetic fields, velocities,
and heating events of the chromosphere and photosphere in detail. NICO
will introduce new technologies to solar flight missions, such as
wavefront sensing for monitoring telescope alignment, real-time
correlation tracking and high-speed image motion compensation, and
wide aperture Fabry-Perot etalons for extended spectral scanning.

---------------------------------------------------------
Title: Magnetic Helicity in Filaments, CMES and Magnetic Clouds
Authors: Rust, David
2003IAUJD...3E..23R Altcode:
Filaments coronal mass ejections (CMEs) and magnetic clouds (MCs) all
show signatures of twisted and writhing magnetic fields. CMEs are often
associated with MCs whose fields are regularly probed with sensitive
magnetometers. These measurements reveal that MC fields are helical
and each cloud carries magnetic helicity away from the sun. It is more
difficult to determine the helicity of the corresponding features -
filaments and coronal structures - on the sun. This talk will survey
helicity estimates of solar features including their hemispherical
distributions and evidence for writhe and twist in the fields. The
distribution of magnetic helicity in the solar atmosphere may provide
important clues to the workings of the solar dynamo.

---------------------------------------------------------
Title: The helicial flux rope structure of solar filaments
Authors: Rust, D. M.
2003AdSpR..32.1895R Altcode:
According to J. B. Taylor's relaxation theory for magnetized plasmas,
helical flux ropes should be the fundamental building blocks of
magnetism in the solar atmosphere. Although flux ropes are clearly
ejected from the Sun, there has been some controversy about whether they
exist in the sun's atmosphere before ejection. The issue is important
because of the need to understand how eruptions are initiated. A clearer
picture of solar flux ropes is emerging with recent high-resolution
observations of solar filaments. Their twist and writhe are frequently
detectable. This report describes some examples of filaments that
suddenly writhe (kink) and do not escape the sun. The observations
of November 1, 2001 and May 27, 2002 both appear to show the sudden
eruption of a filament with probable transformation of some internal
twist into a writhe of approx. + 1. Also described is one event in
which a well observed filament did erupt. It is associated with a
magnetic flux rope detected with the NEAR spacecraft magnetometer.

---------------------------------------------------------
Title: Transport of Helicity and Dynamics of Solar Active Regions
Authors: Georgoulis, Manolis K.; Rust, David M.; Labonte, Barry J.
2003IAUJD...3E..29G Altcode:
We outline a simple method to monitor variations of the magnetic
helicity the current helicity and the non-potential (free) magnetic
energy on the photospheric boundary of solar active regions. Explicit
manifestations of dynamical activity in the solar atmosphere such as
flares coronal mass ejections and filament eruptions may be related to
these variations. While similar methods require knowledge of the vector
potential and the velocity field vector on the photosphere our method
requires only the photospheric potential magnetic field corresponding
to the observed magnetograms. The calculation of the potential field
for any given magnetogram is straightforward. Moreover our method
relies on the constant-alpha force-free approximation assumed to hold
in the active region. Whether the above is a realistic assumption
can be tested using an array of well-documented methods. Therefore
our technique may prove quite useful to at least a subset of active
regions in which the linear force-free approximation is justifiable.

---------------------------------------------------------
Title: Flare Genesis Experiment: magnetic topology of Ellerman bombs
Authors: Schmieder, B.; Pariat, E.; Aulanier, G.; Georgoulis, M. K.;
Rust, D. M.; Bernasconi, P. N.
2002ESASP.506..911S Altcode: 2002svco.conf..911S; 2002ESPM...10..911S
Flare Genesis Experiment (FGE), a balloon borne Observatory was launched
in Antarctica on January 10, 2000 and flew during 17 days. FGE consists
of an 80 cm Cassegrain telescope with an F/1.5 ultra-low-expansion
glass primary mirror and a crystalline silicon secondary mirror. A
helium-filled balloon carried the FGE to an altitude of 37 km
(Bernasconi et al. 2000, 2001). We select among all the observations a
set of high spatial and temporal resolution observations of an emerging
active region with numerous Ellerman bombs (EBs). Statistical and
morphology analysis have been performed. We demonstrate that Ellerman
bombs are the result of magnetic reconnection in the low chromosphere
by a magnetic topology analysis. The loci of EBs coincide with "bald
patches" (BPs). BPs are regions where the vector field is tangential to
the boundary (photosphere) along an inversion line. We conclude that
emerging flux through the photosphere is achieved through resistive
emergence of U loops connecting small Ω loops before rising in the
chromosphere and forming Arch Filament System (AFS).

---------------------------------------------------------
Title: Statistics, morphology, and energetics of Ellerman bombs
Authors: Georgoulis, Manolis K.; Rust, David M.; Bernasconi, Pietro
N.; Schmieder, Brigitte
2002ESASP.505..125G Altcode: 2002IAUCo.188..125G; 2002solm.conf..125G
We have performed a detailed analysis of several hundreds Hα Ellerman
bombs in the low chromosphere, above an emerging flux region. We
find that Ellerman bombs may be small-scale, low-altitude, magnetic
reconnection events that heat the low chromosphere in the active
region. Their energy content varies between 1027 erg and
1028 erg, typical of sub-flaring activity.

---------------------------------------------------------
Title: The Near-Infrared Chromosphere Observatory
Authors: Rust, David M.; Bernasconi, Pietro N.; Labonte, Barry J.;
Georgoulis, Manolis K.; Fox, Nicola J.; Kalkofen, Wolfgang; Lin,
Haoseng
2002ESASP.505..561R Altcode: 2002IAUCo.188..561R; 2002solm.conf..561R
The Near-Infrared Chromosphere Observatory (NICO) is a proposed
balloon-borne observatory aiming to investigate the magnetic structure
and the sources of heating in the solar chromosphere. NICO will be based
on the successful Flare Genesis Experiment (FGE), a pioneer in applying
novel technologies for the study of the Sun. NICO will map magnetic
fields, velocity fields, and heating events in the chromosphere with
unprecedented quality.

---------------------------------------------------------
Title: Vector magnetic field observations of flux tube emergence
Authors: Schmieder, B.; Aulanier, G.; Pariat, E.; Georgoulis, M. K.;
Rust, D. M.; Bernasconi, P. N.
2002ESASP.505..575S Altcode: 2002IAUCo.188..575S; 2002solm.conf..575S
With Flare Genesis Experiment (FGE), a balloon borne Observatory high
spatial and temporal resolution vector magnetograms have been obtained
in an emerging active region. The comparison of the observations
(FGE and TRACE) with a linear force-free field analysis of the region
shows where the region is non-force-free. An analysis of the magnetic
topology furnishes insights into the existence of "bald patches"
regions (BPs are regions where the vector field is tangential to the
boundary (photosphere) along an inversion line). Magnetic reconnection
is possible and local heating of the chromopshere is predicted near the
BPs. Ellerman bombs (EBs) were found to coincide with few BPs computed
from a linear force-free extrapolation of the observed longitudinal
field. But when the actual observations of transverse fields were used
to identify BPs, then the correspondence with EB positions improved
significantly. We conclude that linear force-free extrapolations must
be done with the true observed vertical fields, which require the
measurement of the three components of the magnetic field.

---------------------------------------------------------
Title: Moving Dipolar Features in an Emerging Flux Region
Authors: Bernasconi, P. N.; Rust, D. M.; Georgoulis, M. K.; Labonte,
B. J.
2002SoPh..209..119B Altcode:
On 25 January, 2000, we observed active region NOAA 8844 with the
Flare Genesis Experiment (FGE), a balloon-borne observatory with an
80-cm solar telescope. FGE was equipped with a vector polarimeter and
a tunable Fabry-Pérot narrow-band filter. It recorded time series of
filtergrams, vector magnetograms and Dopplergrams at the Ca i 6122.2 Å
line, and Hα filtergrams with a cadence between 2.5 and 7.5 min. At
the time of the observations, NOAA 8844 was located at approximately
5° N 30° W. The region was growing rapidly; new magnetic flux was
constantly emerging in three supergranules near its center. We report on
the structure and behavior of peculiar moving dipolar features (MDFs)
in the emerging flux, and we describe in detail how the FGE data were
analyzed. In longitudinal magnetograms, the MDFs appeared to be small
dipoles flowing into sunspots and supergranule boundaries. Previously,
dipolar moving magnetic features (MMFs) have only been observed
flowing out from sunspots. The FGE vector magnetograms show that the
MDFs occurred in a region with nearly horizontal fields, the MDFs
being distinguished as undulations in these fields. We identify the
MDFs as stitches where the emerging flux ropes were still tied to the
photosphere by trapped mass. We present a U-loop model that accounts for
their unusual structure and behavior, as well as showing how emerging
flux sheds entrained mass.

---------------------------------------------------------
Title: Statistics, Morphology, and Energetics of Ellerman Bombs
Authors: Georgoulis, Manolis K.; Rust, David M.; Bernasconi, Pietro
N.; Schmieder, Brigitte
2002ApJ...575..506G Altcode:
We investigate the statistical properties of Ellerman bombs in the
dynamic emerging flux region NOAA Active Region 8844, underneath
an expanding arch filament system. High-resolution chromospheric
Hα filtergrams (spatial resolution 0.8"), as well as photospheric
vector magnetograms (spatial resolution 0.5") and Dopplergrams, have
been acquired by the balloon-borne Flare Genesis Experiment. Hα
observations reveal the first “seeing-free” data set on Ellerman
bombs and one of the largest samples of these events. We find that
Ellerman bombs occur and recur in preferential locations in the low
chromosphere, either above or in the absence of photospheric neutral
magnetic lines. Ellerman bombs are associated with photospheric
downflows, and their loci follow the transverse mass flows on the
photosphere. They are small-scale events, with typical size 1.8"×1.1"
, but this size depends on the instrumental resolution. A large number
of Ellerman bombs are probably undetected, owing to limited spatial
resolution. Ellerman bombs occur in clusters that exhibit fractal
properties. The fractal dimension, with an average value ~1.4, does
not change significantly in the course of time. Typical parameters
of Ellerman bombs are interrelated and obey power-law distribution
functions, as in the case of flaring and subflaring activity. We find
that Ellerman bombs may occur on separatrix, or quasi-separatrix,
layers, in the low chromosphere. A plausible triggering mechanism
of Ellerman bombs is stochastic magnetic reconnection caused by the
turbulent evolution of the low-lying magnetic fields and the continuous
reshaping of separatrix layers. The total energies of Ellerman bombs
are estimated in the range (1027, 1028) ergs, the
temperature enhancement in the radiating volume is ~2×103
K, and the timescale of radiative cooling is short, of the order of
a few seconds. The distribution function of the energies of Ellerman
bombs exhibits a power-law shape with an index ~-2.1. This suggests
that Ellerman bombs may contribute significantly to the heating of
the low chromosphere in emerging flux regions.

---------------------------------------------------------
Title: Helicity Build-up and the Role of CMEs
Authors: Rust, D. M.
2002AAS...200.6503R Altcode: 2002BAAS...34..751R
Coronal mass ejections are often associated with interplanetary
magnetic clouds, whose fields are regularly probed with sensitive
magnetometers. The measurements reveal that magnetic cloud fields are
helical, and each cloud carries helicity away from the sun. There is no
known mechanism for returning helicity to the sun. This talk will survey
the possible solar sources of magnetic helicity. Included are fieldline
footpoint motions, effects of Coriolis forces, effects of convection,
shear associated with differential rotation, and, of course, the
internal dynamo. Besides the survey of possible mechanisms for helicity
generation, we will consider the global view of the flow of helicity
from the sun into interplanetary space. This work is supported by the
NASA Solar and Heliospheric Physics Program under grant NAG5-7921.

---------------------------------------------------------
Title: The Near-Infrared Chromosphere Observatory (NICO)
Authors: Rust, D. M.; Bernasconi, P. N.; LaBonte, B. J.; Georgoulis,
M. K.; Kalkofen, W.; Fox, N. J.; Lin, H.
2002AAS...200.3902R Altcode: 2002BAAS...34..701R
NICO is a proposed cost-effective platform for determining the magnetic
structure and sources of heating for the solar chromosphere. It is a
balloon-borne observatory that will use the largest solar telescope
flying and very high data rates to map the magnetic fields, velocities,
and heating events of the chromosphere and photosphere in unprecedented
detail. NICO is based on the Flare Genesis Experiment (FGE), which
has pioneered in the application of technologies important to NASA's
flight program. NICO will also introduce new technologies, such
as wavefront sensing for monitoring telescope alignment; real-time
correlation tracking and high-speed image motion compensation for
smear-free imaging; and wide aperture Fabry-Perot filters for extended
spectral scanning. The telescope is a classic Cassegrain design with
an 80-cm diameter F/1.5 primary mirror made of Ultra-Low-Expansion
glass. The telescope structure is graphite-epoxy for lightweight,
temperature-insensitive support. The primary and secondary mirror
surfaces are coated with silver to reflect more than 97% of the incident
solar energy. The secondary is made of single-crystal silicon, which
provides excellent thermal conduction from the mirror surface to its
mount, with negligible thermal distortion. A third mirror acts as a
heat dump. It passes the light from a 15-mm diameter aperture in its
center, corresponding to a 322"-diameter circle on the solar surface,
while the rest of the solar radiation is reflected back out of the
front of the telescope. The telescope supplies the selected segment
of the solar image to a polarization and spectral analysis package
that operates with an image cadence 1 filtergram/sec. On-board data
storage is 3.2 Terabytes. Quick-look images will be sent in near real
time to the ground via the TDRSS communications link.

---------------------------------------------------------
Title: Photospheric Vertical Current Density and Overlying Atmospheric
Activity in an Emerging Flux Region
Authors: Georgoulis, M. K.; Rust, D. M.; Bernasconi, P. N.;
Schmieder, B.
2002AAS...200.2004G Altcode: 2002BAAS...34..673G
Using high-resolution vector magnetograms obtained by the balloon-borne
Flare Genesis Experiment (FGE), we construct maps of the vertical
current density in the emerging flux region NOAA 8844. The vertical
current density has been decomposed into components that are
field-aligned and perpendicular to the magnetic field, thus allowing
a straightforward identification of force-free areas, as well as of
areas where the force-free approximation breaks down. Small-scale
chromospheric activity, such as H α Ellerman bombs and Ultraviolet
bright points in 1600 Åshow a remarkable correlation with areas of
strong current density. Simultaneous data of overlying coronal loops,
observed by TRACE in the Extreme Ultraviolet (171 Åand 195 Å), have
been carefully co-aligned with the FGE photospheric maps. We find
that the footpoints of the TRACE loops always coincide with strong
vertical currents and enhancements of the current helicity density. We
also investigate whether the force-free approximation is valid on the
photosphere during various evolutionary stages of the active region.

---------------------------------------------------------
Title: Investigation of the Sources of Irradiance Variation on the
Sun (ISIS)
Authors: LaBonte, B. J.; Bernasconi, P. N.; Rust, D.; Foukal, P.;
Hudson, H.; Spruit, H.
2002AAS...200.5608L Altcode: 2002BAAS...34..736L
There is a persistent correlation of the longterm climate change and
solar irradiance. ISIS is designed to understand the physical basis of
this correlation. ISIS combines an innovative bolometric imager and a
multiband CCD imager. The bolometric imager has uniform response from
200 nm to 3000 nm, spatial resolution &lt; 5 arcseconds, and precision
of &lt; 0.1% in a one minute integration. The multiband imager records
ultraviolet irradiance variation in the band from 200 to 350 nm,
measures photospheric temperature structure, and provides chromospheric
structure in Ca II K and H-alpha, with spatial resolution &lt;1.0
arcsecond. Designed for flight on the Solar Dynamics Observatory,
ISIS will provide the comprehensive photometric measurements needed
to characterize the irradiance variation from identifiable structures
and challenge theoretical models of convection and the solar dynamo.

---------------------------------------------------------
Title: The Solar Bolometric Imager
Authors: Bernasconi, P. N.; Foukal, P.; Rust, D. M.
2002AAS...200.5605B Altcode: 2002BAAS...34R.735B
The Solar Bolometric Imager (SBI) is an innovative solar telescope
capable of recording images in essentially total photospheric light,
with an angular resolution of 5", sufficient to distinguish sunspots,
faculae and enhanced network. These are the photospheric magnetic
structures so far linked most closely to irradiance variation. The
balloon-borne SBI will provide the first bolometric maps of the
photosphere, to evaluate the photometric contribution of magnetic
structures more accurately than has been achievable so far, using
spectrally selective imaging over restricted wavebands. More accurate
removal of the magnetic feature contribution will enable us to determine
whether other solar irradiance mechanisms exist besides the effects
of photospheric magnetism. The SBI detector is an array of 320 X 240
ferro-electric thermal IR elements whose spectral absorptance has
been extended and flattened by a deposited layer of gold-black. The
telescope itself is a 30-cm Dall-Kirkham design with uncoated primary
and secondary pyrex mirrors. The combination of telescope and bolometric
array provides an image of the solar irradiance with a flat spectral
response between 0.28 um and 2.6 um, over a field of view of 15.2' X
11.4', and a pixel size of 2.8". After a successful set of ground-based
tests, the instrument is being readied for a one-day stratospheric
balloon flight that will take place in September 2003. The observing
platform will be the gondola previously used for the Flare Genesis
Experiment project (FGE), retrofitted to house and control the SBI
telescope and detector. The balloon flight will enable SBI to image over
essentially the full spectral range accepted by non-imaging space borne
radiometers such as ACRIM, making the data sets complementary. The SBI
flight will also provide important engineering data to validate the
space worthiness of the novel gold-blackened thermal array detectors,
and verify the thermal performance of the SBI's uncoated optics in a
vacuum environment. This work was funded by NASA under grant NAG5-10998.

---------------------------------------------------------
Title: An Automated System for Detecting Sigmoids in Solar X-ray
Images
Authors: LaBonte, B. J.; Rust, D. M.; Bernasconi, P. N.
2002AGUSMSH52A..02L Altcode:
The probability of a coronal mass ejection (CME) occurring is linked
to the appearance of structures, called sigmoids, in satellite X-ray
images of the sun. By examination of near real time images, we can
detect sigmoids visually and estimate the probability of a CME and
the probability that it will cause a major geomagnetic storm. We have
devised a pattern recognition system to detect the sigmoids in Yohkoh
and GOES (when available) X-ray images automatically. When implemented
in a near real time environment, this system should allow long term,
3 - 7 day, forecasts of CMEs and their potential for causing major
geomagnetic storms.

---------------------------------------------------------
Title: Magnetic helicity, coronal mass ejections and the solar cycle
Authors: Rust, David M.
2002ESASP.477...39R Altcode: 2002scsw.conf...39R
Here is a brief review of current thinking about the origin and
function of magnetic helicity in coronal mass ejections. Magnetic
helicity is thought to be generated either by the solar dynamo, by
Coriolis forces in the turbulent convection zone, or by differential
rotation's effective shearing of coronal fields. The mechanisms are
discussed, especially with regard to what they suggest that observers
should use to detect the build-up of helicity in coronal features so
that the onset of a CME can be forecast.

---------------------------------------------------------
Title: Magnetic measurements of flux emergence
Authors: Rust, David
2002ocnd.confE..33R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Comparison of magnetic helicity close to the sun and in
magnetic clouds
Authors: Rust, D.
2002cosp...34E1203R Altcode: 2002cosp.meetE1203R
Magnetic helicity is present in the solar atmosphere - as inferred from
vector magnetograph measurements, solar filaments, S-shaped coronal
structures known as sigmoids, and sunspot whorls. I will survey
the possible solar sources of this magnetic helicity. Included are
fieldline footpoint motions, effects of Coriolis forces, effects of
convection, shear associated with differential rotation, and, of course,
the internal dynamo. Besides the survey of possible local mechanisms
for helicity generation, I will consider the global view of the flow
of helicity from the sun into interplanetary space. The principal
agents by which the sun sheds helicity are coronal mass ejections
(CMEs). They are often associated with interplanetary magnetic clouds
(MCs), whose fields are regularly probed with sensitive spacecraft
magnetometers. MCs yield more direct measurements of helicity. They
show that each MC carries helicity away from the sun. A major issue
in solar-heliospheric research is whether the amount of helicity
that MCs carry away in a solar cycle can be accounted for by the
helicity generation mechanisms proposed so far. The NASA Solar and
Heliospheric Physics Program supports this work under grants NAG5-
7921 and NAG 5-11584.

---------------------------------------------------------
Title: The solar bolometric imager
Authors: Rust, D.; Bernasconi, P.; Foukal, P.
2002cosp...34E1200R Altcode: 2002cosp.meetE1200R
The balloon-borne Solar Bolometric Imager (SBI) will provide the
first bolometric (integrated light) maps of the photosphere, to
evaluate the photometric contribution of magnetic structures more
accurately than has been achievable with spectrally selective imaging
over restricted wavebands. More accurate removal of the magnetic
feature contribution will enable us to determine if solar irradiance
variation mechanisms exist other than the effects of photospheric
magnetism. The SBI detector is an array of 320 x 240 ferro -electric
thermal IR elements whose spectral absorptance has been extended and
flattened by a deposited layer of gold- black. The telescope itself is
a 30-cm Dall-Kirkham design with uncoated primary and secondary pyrex
mirrors. The combination of telescope and bolometric array provides
an image of the sun with a flat spectral response between 0.28 microns
and 2.6 microns, over a field of view of 15.2 x 11.4 min, and a pixel
size of 2.8 arcsec. After a successful set of ground-based tests, the
instrument is being readied for a one-day stratospheric balloon flight
that will take place in September 2003. The observing platform will be
the gondola previously used for the Flare Genesis Experiment (FGE),
retrofitted to house and control the SBI telescope and detector. The
balloon flight will enable SBI to image over essentially the full
spectral range accepted by non-imaging space-borne radiometers such
as ACRIM, making the data sets complementary. The SBI flight will also
provide important engineering data to validate the space worthiness of
the novel gold-blackened thermal array detectors, and verify the thermal
performance of the SBI's uncoated optics in a vacuum environment. This
work was funded by NASA under grant NAG5-10998.

---------------------------------------------------------
Title: The Flare Genesis Experiment
Authors: Rust, D. M.
2002STIN...0246802R Altcode:
Using the Flare Genesis Experiment (FGE), a balloon-borne observatory
with an 80-cm solar telescope we observed the active region NOAA 8844
on January 25, 2000 for several hours. FGE was equipped with a vector
polarimeter and a tunable Fabry-Perot narrow-band filter. It recorded
time series of filtergrams, vector magnetograms, and Dopplergrams at
the Ca(I) 6122.2 angstrom line, and H-alpha filtergrams with a cadence
between 2.5 and 7.5 minutes. At the time of the observations, NOAA 8844
was located at approximately 5 N 30 W. The region was rapidly growing
during the observations; new magnetic flux was constantly emerging
in three supergranules near its center. We describe in detail how
the FGE data were analyzed and report on the structure and behavior
of peculiar moving dipolar features (MDFs) observed in the active
region. In longitudinal magnetograms, the MDFs appeared to be small
dipoles in the emerging fields. The east-west orientation of their
polarities was opposite that of the sunspots. The dipoles were oriented
parallel to their direction of motion, which was in most cases towards
the sunspots. Previously, dipolar moving magnetic features have only
been observed flowing out from sunspots. Vector magnetograms show that
the magnetic field of each MDF negative part was less inclined to the
local horizontal than the ones of the positive part. We identify the
MDFs as undulations, or stitches, where the emerging flux ropes are
still tied to the photosphere. We present a U-loop model that can
account for their unusual structure and behavior, and it shows how
emerging flux can shed its entrained mass.

---------------------------------------------------------
Title: A new paradigm for solar filament eruptions
Authors: Rust, David M.
2001JGR...10625075R Altcode:
This article discusses the formation, magnetic structure, and eruption
of solar filaments in terms of two contrasting paradigms. The
standard paradigm is that filaments are formed by condensation of
plasma on coronal magnetic fields that are twisted or dimpled as a
result of photospheric motions. According to this paradigm, filaments
erupt when photospheric motions shear the fields, increasing their
energy and decreasing their stability. According to a new paradigm,
subsurface motions generate toroidal magnetic flux ropes, and after
these flux ropes emerge to form active regions, the most twisted
parts migrate into the corona to form filaments. Filaments become
unstable and are ejected after a sufficient accumulation of twist
(i.e., magnetic helicity). Various proposed mechanisms for producing
the needed helicity are reviewed, and several observational tests are
proposed to differentiate among the possible mechanisms.

---------------------------------------------------------
Title: Sunspot Formation from Emerging Flux Ropes - Observations
from Flare Genesis
Authors: Rust, D. M.; Bernasconi, P. N.; Georgoulis, M. K.; LaBonte,
B. J.; Schmieder, B.
2001AGUSM..SP42A09R Altcode:
From January 10 to 27, 2000, the Flare Genesis payload observed
the Sun while suspended from a balloon in the stratosphere above
Antarctica. The goal of the mission was to acquire a long time series of
high-resolution images and vector magnetograms of the solar photosphere
and chromosphere. We obtained images, magnetograms and Dopplergrams
in the magnetically sensitive Ca I line at 6122 Angstroms. Additional
simultaneous images were obtained in the wing of H-alpha. On January
25, 2000, we observed in NOAA region 8844 at N05 W30. The rapid
development of a sunspot group that apparently included a delta spot
(two polarities within one umbra). We considered a variety of models
for interpreting these observations, including a twisted flux tube,
a bipole that annihilates, a bipole that submerges, and a field
distorted by mass loading. From the vector magnetograms and Doppler
measurements, we conclude that nearly horizontal flux ropes are swept
into the developing spot where they tilt upward to contribute to the
familiar nearly vertical sunspot fields. The largest flux rope exhibited
a twisted structure, and its angle with respect to the vertical was so
great that it could be mistaken for a positive magnetic field merging
into a negative sunspot. Flare Genesis was supported by NASA grant
NAG5-8331 and by NSF grant OPP-9909167.

---------------------------------------------------------
Title: Ellerman Bombs in a Solar Active Region: Statistical Properties
and Implications
Authors: Georgoulis, M. K.; Rust, D. M.; Bernasconi, P. N.
2001AGUSM..SP52B05G Altcode:
We have embedded the concept of Self-Organized Criticality (SOC) in
deterministic Cellular Automata (CA) models in an attempt to simulate
the emergence of flaring and sub-flaring activity in solar active
regions. SOC CA models reproduce reasonably well several aspects of the
statistical properties of flares and, moreover, they allow predictions
regarding the respective properties of the unresolved nanoflares. We
compare the above-mentioned predictions with observed arcsecond and
sub-arcsecond activity on the low-chromosphere, in a newly formed active
region. The source of the observations is the Flare Genesis Experiment
(FGE) which has provided us with high-resolution maps of the magnetic
field and the velocity field vectors on the photospheric boundary, as
well as Hα filtergrams on the low-chromosphere. Moreover, UV and EUV
data from TRACE are used for determining the activity on the overlying
atmospheric layers. We present preliminary results on the statistical
properties of transient Hα brightenings (Ellerman Bombs) which
correlate well with significant overlying UV emission. Implications
of these results, as well as potential directions for modeling the
low-lying activity in the solar atmosphere are discussed. This work
was sponsored by NASA grant NAG5-8331 and NSF grant OPP-9909162

---------------------------------------------------------
Title: Peculiar Moving Magnetic Features Observed With the Flare
Genesis Experiment
Authors: Bernasconi, P. N.; Rust, D. M.; Georgoulis, M. K.; LaBonte,
B. J.; Schmieder, B.
2001AGUSM..SP51A02B Altcode:
With the Flare Genesis Experiment (FGE), a balloon-borne 80-cm solar
telescope, we observed the active region NOAA 8844 on January 25,
2000 for several hours. FGE was equipped with a vector polarimeter
and a lithium-niobate Fabry-Perot narrow-band filter. It recorded
time series of filtergrams, vector magnetograms, and dopplergrams
at the CaI 6122.2 Angstroms line, as well as Hα filtergrams, with a
cadence between 2.5 and 7.5 minutes. At the time of the observations
NOAA 8844 was located at approximately 5 deg N, 30 deg W. It was a new
flux emergence that first appeared on the solar disk two days before
and was still showing a very dynamic behavior. Its two main polarity
parts were rapidly moving away from each other and new magnetic flux
was constantly emerging from its center. Here we describe the structure
and behavior of peculiar small moving magnetic dipoles (called moving
magnetic features MMF's) that we observed near the trailing negative
polarity sunspot of NOAA 8844. Presentations by D. M. Rust, and by
M. K. Georgoulis at this meeting will focus on other aspects of the
same active region. The MMF's took the form of small dipoles that first
emerged into the photosphere near the center of a supergranular cell
located next to the main trailing flux concentration. They rapidly
migrated towards the spot, following the supergranular flow. The two
polarities of the little dipoles did not separate; they moved together
with same speed and in the same direction. The dipoles were oriented
parallel to their motion toward the negative spot, with the positive
polarity always leading. MMF's usually move away from sunspots, and
their orientation is the reverse of what we see here. In addition,
we noted that the dipole structure was not symmetric. The field lines
of the trailing part of the MMF's (negative polarity) were always
much more perpendicular to the local horizontal than the ones of the
leading part. The trailing part looked more compact and circular, while
the leading part was more elongated in the direction of the motion. We
conclude that we observed a new type of MMF's with a totally different
magnetic structure than previously seen. We present a possible model
that could explain their unusual structure and behavior. This work
was supported by NASA grant NAG5-8331 and NSF grant OPP-9909167.

---------------------------------------------------------
Title: High Resolution Vector Magnetograms with the Flare Genesis
Vector Polarimeter
Authors: Bernasconi, P. N.; Rust, D. M.; Eaton, H. A. C.
2001ASPC..236..399B Altcode: 2001aspt.conf..399B
No abstract at ADS

---------------------------------------------------------
Title: The origin and development of the May 1997 magnetic cloud
Authors: Webb, D. F.; Lepping, R. P.; Burlaga, L. F.; DeForest, C. E.;
Larson, D. E.; Martin, S. F.; Plunkett, S. P.; Rust, D. M.
2000JGR...10527251W Altcode:
A complete halo coronal mass ejection (CME) was observed by the SOHO
Large-Angle and Spectrometric Coronagraph (LASCO) coronagraphs on May
12, 1997. It was associated with activity near Sun center, implying that
it was aimed earthward. Three days later on May 15 an interplanetary
shock and magnetic cloud/flux rope transient was detected at the Wind
spacecraft 190 RE upstream of Earth. The long enduring
southward magnetic fields associated with these structures triggered a
geomagnetic storm. The CME was associated with a small coronal arcade
that formed over a filament eruption with expanding double ribbons
in Hα emission. The flare was accompanied by a circular EUV wave,
and the arcade was flanked by adjacent dimming regions. We surmise
that these latter regions marked the feet of a flux rope that expanded
earthward into the solar wind and was observed as the magnetic cloud
at Wind. To test this hypothesis we determined key parameters of the
solar structures on May 12 and compared them with the modeled flux
rope parameters at Wind on May 15. The measurements are consistent
with the flux rope originating in a large coronal structure linked
to the erupting filament, with the opposite-polarity feet of the rope
terminating in the depleted regions. However, bidirectional electron
streaming was not observed within the cloud itself, suggesting that
there is not always a good correspondence between such flows and ejecta.

---------------------------------------------------------
Title: Solar Chromosphere: Ellerman Bombs
Authors: Rust, D.
2000eaa..bookE2263R Altcode:
In 1917, Ellerman discovered short-lived, intense brightenings at
tiny (&lt;1 arcsec) points in the lower solar CHROMOSPHERE. A typical
Ellerman bomb lasts less than 10 min. Its spectrum is characterized
by very broad emission wings on the hydrogen Balmer lines. On a
photographic negative, the pattern of a bomb's emission resembles a
mustache or whisker. Reinforcing the allusion to mustaches is the ...

---------------------------------------------------------
Title: Solar Prominences
Authors: Rust, D.
2000eaa..bookE2044R Altcode:
Prominences are clouds of relatively cool and dense gas in the solar
atmosphere. These clouds change shape and come and go, but they do not
drift like terrestrial clouds. Prominences are suspended above magnetic
channels (see SOLAR FILAMENT CHANNELS) that change little from day
to day. They are trapped in magnetic fields in the solar atmosphere,
but they churn slowly, at heights of up to 100 000 ...

---------------------------------------------------------
Title: The Solar Terrestrial Relations Observatory - Mission Overview
Authors: Davila, J. M.; Rust, D. M.; Sharer, P. J.
2000SPD....31R0293D Altcode: 2000BAAS...32.1291D
Starting in 2004, the two identical STEREO spacecraft will drift slowly
off the Sun-Earth line, providing a series of differing perspectives
on CMEs and other solar and heliospheric structures. At the end
of the prime science (2-year) mission, the spacecraft will each be
about 45 degrees from Earth, one leading Earth and one trailing. Each
spacecraft will carry a cluster of telescopes, including coronagraphs,
EUV imagers, and particle detectors. When the images are combined with
solar magnetograms and other data from observatories on the ground or
in low Earth orbit, both the buildup of magnetic energy and the lift
off and trajectory of CMEs can be studied. Interpreting the STEREO
data will pose a new challenge to the solar community. We discuss
the STEREO mission design, instrument complement and the development
of the trajectory design that, we believe, maximizes the scientific
potential of the mission.

---------------------------------------------------------
Title: Solar Filaments as Tracers of Sub-surface Processes
Authors: Rust, D. M.
2000JApA...21..177R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Balloon-borne telescope for high-resolution solar imaging
and polarimetry
Authors: Bernasconi, Pietro N.; Rust, David M.; Eaton, Harry A.;
Murphy, Graham A.
2000SPIE.4014..214B Altcode:
In January 2000, an 80-cm F/1.5 Ritchey-Chretien solar telescope
flew for 17 days suspended from a balloon in the stratosphere above
Antarctica. The goal was to acquire long time series of high spatial
resolution images and vector- magnetograms of the solar photosphere
and chromosphere. Such observations will help to advance our basic
scientific understanding of solar activity, in particular flares. Flying
well above the turbulent layers of the Earth's atmosphere, the telescope
should be able to operate close to its diffraction limited resolution
of 0.2 arcsec, providing high resolution observations of small scale
solar features. To achieve this goal we developed a platform for the
optical telescope that is stable to nearly 10 arcsec. We also developed
an image motion compensation system that stabilizes the solar image
on the CCD focal plane to about 1 arcsec.

---------------------------------------------------------
Title: New Results from the Flare Genesis Experiment
Authors: Rust, D. M.; Bernasconi, P. N.; Eaton, H. A.; Keller, C.;
Murphy, G. A.; Schmieder, B.
2000SPD....31.0302R Altcode: 2000BAAS...32..834R
From January 10 to 27, 2000, the Flare Genesis solar telescope
observed the Sun while suspended from a balloon in the stratosphere
above Antarctica. The goal of the mission was to acquire long time
series of high-resolution images and vector magnetograms of the
solar photosphere and chromosphere. Images were obtained in the
magnetically sensitive Ca I line at 6122 Angstroms and at H-alpha
(6563 Angstroms). The FGE data were obtained in the context of Max
Millennium Observing Campaign #004, the objective of which was to study
the “Genesis of Solar Flares and Active Filaments/Sigmoids." Flare
Genesis obtained about 26,000 usable images on the 8 targeted active
regions. A preliminary examination reveals a good sequence on an
emerging flux region and data on the M1 flare on January 22, as well
as a number of sequences on active filaments. We will present the
results of our first analysis efforts. Flare Genesis was supported
by NASA grants NAG5-4955, NAG5-5139, and NAG5-8331 and by NSF grant
OPP-9615073. The Air Force Office of Scientific Research and the
Ballistic Missile Defense Organization supported early development of
the Flare Genesis Experiment.

---------------------------------------------------------
Title: Design and Performance of the Flare Genesis Experiment
Authors: Bernasconi, P. N.; Rust, D. M.; Eaton, H. A.; Murphy, G. A.
2000SPD....31.0289B Altcode: 2000BAAS...32..826B
In January 2000, an 80-cm F/1.5 Ritchey-Chretien solar telescope
flew for18 days suspended from a balloon in the stratosphere above
Antarctica. The goal of the flight was to acquire long time series of
high-resolution images and vector magnetograms of the solar photosphere
and chromosphere. Such observations will help to advance our basic
scientific understanding of solar activity, in particular, flares and
coronal mass ejections. Flying well above the turbulent layers of
the Earth's atmosphere, the telescope obtained unprecedented sharp
and stable observations of small-scale solar features. To achieve
this goal we developed a platform for the optical telescope that is
stable to nearly 10 arcsec. In addition, we developed an image motion
compensation system that stabilizes the solar image on the focal
plane to about 1 arcsec. When the payload was in line of sight with
the ground station, communications were accomplished via a low-speed
radio link for sending commands and receiving telemetry and a high-speed
downlink for receiving images. During the rest of the flight, contact
with the payload was sporadic and only instrument status could be
telemetered down. After the flight, the data were recovered from
on-board tapes. This presentation will focus on the description of
the instrument and its operating principle. Preliminary results from
the January 2000 flight will be presented in a companion paper.

---------------------------------------------------------
Title: Solar physics at APL.
Authors: Rust, D. M.
1999JHATD..20..570R Altcode:
Solar reserach at APL aims to understand the fundamental physics
that govern solar activity. The tools are telescopes, models, and
interplanetary sampling of solar ejecta. The work is relevant to APL's
mission because solar energetic protons disable satellites and endanger
astronauts. Solar activity also causes geomagnetic storms, which can
lead to communications disruptions, electric power network problems,
satellite orbit shifts and, sometimes, satellite failure. Predicting
storm conditions requires understanding solar magnetism and its
fluctuations. APL scientists have made major contributions to solar
activity research and have taken the lead in developing a variety
of new solar research tools. They are now starting work on the Solar
Terrestrial Relations Observatory, a major space mission.

---------------------------------------------------------
Title: A Search for Toroidal Magnetic Fields in the Solar Photosphere
Authors: Rust, D. M.
1999AAS...194.9404R Altcode: 1999BAAS...31..991R
Observations of an East-West asymmetry in photospheric magnetic fields,
as reported by Duvall et al. (Solar Phys. 61, 233, 1979), Howard (Solar
Phys. 39, 275, 1974, and Solar Phys. 134, 233, 1991), and Shrauner and
Scherrer (Solar Phys. 153, 131, 1994) may possibly be explained in terms
of a normal component contaminated by a toroidal component. The toroidal
component has already been traced in solar filaments and by its effect
on chromospheric fine structure. Taking advantage of the highly stable
observing conditions offered by the SOHO Michelson-Doppler Imager (MDI),
we searched for evidence of toroidal fields in the photosphere. Although
the MDI is sensitive only to the line-of-sight component of the fields,
toroidal fields reveal themselves by East-West asymmetries in average
field strength and in large-scale features, such as boundaries between
positive and negative fields. We report on analysis of calibrated
full-disk MDI magnetograms for a one-year period.

---------------------------------------------------------
Title: High Resolution polarimetry with a Balloon-Borne Telescope:
The Flare Genesis Experiment
Authors: Bernasconi, P.; Rust, D.; Murphy, G.; Eaton, H.
1999ASPC..183..279B Altcode: 1999hrsp.conf..279B
No abstract at ADS

---------------------------------------------------------
Title: Intercomparison of NEAR and Wind interplanetary coronal mass
ejection observations
Authors: Mulligan, T.; Russell, C. T.; Anderson, B. J.; Lohr, D. A.;
Rust, D.; Toth, B. A.; Zanetti, L. J.; Acuna, M. H.; Lepping, R. P.;
Gosling, J. T.
1999JGR...10428217M Altcode:
Nearly 4 months of continuous interplanetary magnetic field measurements
September 1997 through December 1997 have allowed us to compare four
interplanetary coronal mass ejection (ICME) events seen by the NEAR and
Wind spacecraft. When the spacecraft are in close proximity (separated
by 1° in azimuth relative to the sun) the ICMEs seen by Wind and NEAR
have similar signatures as expected for structures with dimensions
along the solar wind flow of ~0.2 AU. When the NEAR spacecraft is
separated by ~5.4° in azimuth from the Earth the vector signature
of ICMEs seen at NEAR begins to differ from those seen at Wind even
though the magnitude of the field in the events and the background
solar wind show similarities at the two spacecraft. When the spacecraft
are separated by 11.3° the magnetic signatures are quite different and
sometimes ICMEs are seen only at one of the two locations. Nevertheless,
in all cases the magnetic helicity of the cloud structures seen at
NEAR is the same as at Wind. The radial speeds of the shock and ICME
leading edge as they cross Wind and the time delays of those events,
for which we have some assurance that they also arrived at NEAR,
indicate that the ICMEs decelerate measurably as they travel near 1 AU.

---------------------------------------------------------
Title: Magnetic Helicity in Solar Filaments and Coronal Mass Ejections
Authors: Rust, D. M.
1999GMS...111..221R Altcode: 1999mhsl.conf..221R
Erupting solar filaments are often coiled and the knots of plasma in
them rotate as though constrained to follow helical magnetic field
lines. Starting with this evidence of magnetic helicity in filaments,
this article reviews observations and recent models of solar filaments
with an emphasis on how to infer their magnetic helicity. Results
from telescopic observations are often controversial. They are being
supplemented by in situ measurements of the ejected magnetic fields
and plasmas that pass by interplanetary spacecraft. Correlations
of solar events with interplanetary magnetic cloud properties yield
insights into the nature of magnetic helicity on the Sun. Examples
include the segregation of magnetic helicity, with negative/positive
helicity dominating in the north/south, and an association of filament
eruptions with helical kink instabilities.

---------------------------------------------------------
Title: The Solar STEREO Mission
Authors: Rust, D. M.
1998ESASP.417..133R Altcode: 1998cesh.conf..133R
No abstract at ADS

---------------------------------------------------------
Title: New Perspectives on Solar Prominences
Authors: Webb, David F.; Schmieder, Brigitte; Rust, David M.
1998ASPC..150.....W Altcode: 1998npsp.conf.....W; 1998IAUCo.167.....W
No abstract at ADS

---------------------------------------------------------
Title: Solar Flares
Authors: Rust, David
1998fsam.conf...81R Altcode:
The Sun is constantly changing. Not an hour goes by without a rise
or fall in solar x-radiation or radio emission. Not a day goes by
without a solar flare. Our active star, this inconsistent Sun, this
gaseous cloud that blows in all directions, warms the air we breathe
and nourishes the food we eat. From Earth, it seems the very model of
stability, but in space it often creates havoc. Over the past century,
solar physicists have learned how to detect even the weakest of solar
outbursts or flares. We know that flares must surely trace their origins
to the magnetic strands stretched and tangled by the rolling plasma of
the solar interior. Although a century of astrophysical research has
produced widely accepted, fundamental understanding about the Sun,
we have yet to predict successfully the emergence of any magnetic
fields from inside the Sun or the ignition of any flare. As in any
physical experiment, the ability to predict events not only validates
the scientific ideas, it also has practical value. In astrophysics,
a demonstrated understanding of sunspots, flares, and ejections of
plasma would allow us to approach many other mysteries, such as stellar
X-ray bursters, with tested theories.

---------------------------------------------------------
Title: European Plans for the Solar/Heliospheric Stereo Mission
Authors: Bothmer, V.; Bougeret, J. -L.; Cargill, P.; Davila, J.;
Delaboudiniere, J. -P.; Harrison, R.; Koutchmy, S.; Liewer, P.;
Maltby, P.; Rust, D.; Schwenn, R.
1998ESASP.417..145B Altcode: 1998cesh.conf..145B
No abstract at ADS

---------------------------------------------------------
Title: Analysis of SOHO Images and NEAR Magnetometer Data on the
Coronal Mass Ejection from the Sun's West Limb on August 13, 1997
Authors: Rust, D. M.; Anderson, B. J.; Andrews, M. D.; Strachan, L.;
Zanetti, L. J.
1998EOSTr..79..257R Altcode:
Coronal observations made by the SOHO telescopes provide unprecedented
information on coronal dynamics including corona mass ejections. The
best images and spectra are obtained for events that take place
within 30 degrees of the plane of the sky. It is difficult to combine
analyses of these data with analyses of in-situ data on CME debris in
interplanetary space because in-situ data are generally available only
for events aimed at Earth. However, the NEAR (Near-Earth Asteroid
Rendezvous) spacecraft trajectory to the asteroid Eros provides
opportunities to combine interplanetary magnetic field observations well
off the Sun-Earth line with SOHO coronal imaging. We present an analysis
of a CME that was ejected off the west limb of the Sun on August 13,
1997. As observed by the SOHO telescopes, various features in the CME
propagated outward with gradual acceleration so that at 29 solar radii,
velocities of the features ranged between 260 and about 500 km/s, as
projected into the observation plane. At this time the NEAR spacecraft
was 58 to the west of the Sun-Earth line at a distance of 1.78 AU from
the Sun. On August 20, 1997, the NEAR magnetometer observed a magnetic
cloud with a clear flux rope signature for about 6 hours. The flux rope
was embedded in the CME disturbance witch lasted approximately 30 hours
at NEAR. The cloud arrival time at NEAR corresponds to time-averaged
propagation speeds of 400 - 500 km/s. This strongly indicates that
NEAR observed the magnetic cloud associated with the August 13 CME. The
magnetic cloud field had right- hand helicity. The CME appears to have
originated with the disappearance of a southern-hemisphere filament
at 45 degrees west longitude. Southern- hemisphere filaments usually,
have right-hand helicity. Since the twist of the field is known, we
are searching for rotational motions in the CME which could indicate
whether the CME fields are twisting up or unwinding. All in all, this
study demonstrates the type of analyses that can be performed using
coronal imaging and in-situ observations from spacecraft at widely
separated heliolongitudes. Opportunities for such analyses are very
rare now, and they are hindered by limited data sets in the best of
cases, but they will be abundant during the Solar Stereo Mission.

---------------------------------------------------------
Title: The Solar-B Mission
Authors: Antiochos, Spiro; Acton, Loren; Canfield, Richard; Davila,
Joseph; Davis, John; Dere, Kenneth; Doschek, George; Golub, Leon;
Harvey, John; Hathaway, David; Hudson, Hugh; Moore, Ronald; Lites,
Bruce; Rust, David; Strong, Keith; Title, Alan
1997STIN...9721329A Altcode:
Solar-B, the next ISAS mission (with major NASA participation), is
designed to address the fundamental question of how magnetic fields
interact with plasma to produce solar variability. The mission has
a number of unique capabilities that will enable it to answer the
outstanding questions of solar magnetism. First, by escaping atmospheric
seeing, it will deliver continuous observations of the solar surface
with unprecedented spatial resolution. Second, Solar-B will deliver the
first accurate measurements of all three components of the photospheric
magnetic field. Solar-B will measure both the magnetic energy driving
the photosphere and simultaneously its effects in the corona. Solar-B
offers unique programmatic opportunities to NASA. It will continue an
effective collaboration with our most reliable international partner. It
will deliver images and data that will have strong public outreach
potential. Finally, the science of Solar-B is clearly related to the
themes of origins and plasma astrophysics, and contributes directly
to the national space weather and global change programs.

---------------------------------------------------------
Title: The Solar Terrestrial Relations Observatory (STEREO)
Authors: Rust, D. M.
1997SPD....28.1103R Altcode: 1997BAAS...29..915R
One of the most important scientific advances of the space age was
the discovery of coronal mass ejections (CMEs). CMEs can severely
disturb Earth's space environment, but lacking adequate perspective,
no one can tell when a CME will impact Earth or with what effect. No
one has a clear idea of CME structure or extent in interplanetary
space. And, the events that most affect Earth are the ones least likely
to be detected with ground-based or Earth-orbiting telescopes. STEREO
will provide a totally new perspective on solar eruptions and their
consequences for Earth. Achieving this perspective will require moving
away from our customary lookout point. But STEREO means much more
than stereo pictures. Two spacecraft will carry identical clusters of
telescopes, including coronagraphs and X-ray or EUV imagers, and each
will carry identical sets of plasma, magnetic field and energetic
particle detectors. The principal science goal is to determine the
structure and evolution of CMEs and their effects throughout the
heliosphere. We will characterize CMEs at their onset, track them
through interplanetary space, and sample them when the reach Earth's
orbit. STEREO has been recommended for a NASA new start in year 2000
by the Sun Earth Connections Roadmap workshop. The mission is being
studied by a Science Definition Team. The mission and the work of the
team so far will be discussed.

---------------------------------------------------------
Title: Solar Vector Magnetic Field Research
Authors: Rust, David M.
1997STIN...9841524R Altcode:
The principal effort was development and flight of the Flare Genesis
Experiment (FGE). The FGE is a balloon borne solar telescope that can
provide the sharpest view ever of the evolution of activity on the
Sun. The goal of the FGE is to obtain the observations needed for a
breakthrough in solar flare research both sooner and at significantly
lower cost than either a satellite or adaptive optics can offer. The
FGE flight was a historic first. This effort has shown that a meter
class solar telescope can take advantage of the modern long duration
ballooning program in Antarctica to achieve science goals that are
central to solar activity research.

---------------------------------------------------------
Title: Advanced Solar Probe Experiment Module (AD SOLEM)
Authors: McNutt, Ralph L.; Gold, Robert E.; Keath, Edwin P.; Rust,
David M.; Krimigis, Stamatios M.; Zanetti, Lawrence J.; Willey, C. E.;
Williams, B. D.; Kurth, William S.; Gurnett, Donald A.; Acuna, Mario
H.; Burlaga, L.; Gloeckler, G.; Ipavich, Fred M.; Lazarus, Alan J.;
Steinburg, John T.; Brueckner, Guenter E.; Socker, Dennis G.; Holzer,
Tom E.; Bochsler, Peter A.; Kallenbach, Reinald; Roux, Alain
1996SPIE.2804....2M Altcode:
A small, low-power suite of fields and particles and imaging experiments
is required for fulfilling the critical science objectives for a
near-sun flyby mission. We discuss how an integrated instrument suite
using novel sensors and advanced detector/microelectronics/packaging
techniques can be implemented for such a payload. Critical tradeoffs
between science requirements, measurement strategies and these
resource limits are discussed, and critical enabling components are
identified. The instrument site consists of 6 major investigations, some
with multiple sensors, power conditioners for both high and low voltages
and a common DPU. The concept design is essentially a dress-rehearsal
of how a payload could realistically make the measurements needed
to answer the critical science questions while operating within a
real-world physics, engineering and technology context.

---------------------------------------------------------
Title: Missions to the Sun
Authors: Rust, David M.
1996SPIE.2804.....R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Heliospheric Links Explorer (HELIX)
Authors: Rust, David M.; Crooker, N. U.; Golub, Leon; Hundhausen,
A. J.; Lanzerotti, L. J.; Lazarus, Alan J.; Seehafer, Norbert; Zanetti,
Lawrence J.; Zwickl, Ron W.
1996SPIE.2804...39R Altcode:
The proposed HELIX mission consists of two spacecraft that will
enable stereoscopic imaging of solar mass ejections, starting with
their origins on the Sun and continuing to 1 AU and beyond. With a
complement of telescopes and plasma detectors, the HELIX spacecraft
will test magnetic helicity conservation and other approaches to
understanding the physics of solar mass ejections. The mission will
help explain how and why solar ejections occur and how they evolve in
interplanetary space. 3D images and velocity maps and in-situ space
plasma and magnetic field measurements will allow identification and
tracking of ejected plasma. Detection of eruptions aimed at Earth will
be an immediate practical benefit of the mission. The HELIX mission
should lead to the development of a reliable storm prediction capability
that will be of significant value to communications systems operators,
electric power networks, NASA operators and others.

---------------------------------------------------------
Title: Flare Genesis Experiment
Authors: Murphy, Graham A.; Rust, David M.; Strohbehn, Kim; Eaton,
Harry A.; Keil, Stephen L.; Keller, Christoph U.; Wiborg, P. H.
1996SPIE.2804..141M Altcode:
In January 1996, the Flare Genesis Experiment was carried for 19
days by a 29.4 M cu. ft helium-filled balloon in the stratosphere
above Antarctica, during which over 14000 images of the Sun were
recorded. Long-duration ballooning provides a relatively inexpensive
means to observe the Sun under near-space conditions and to develop
instrumentation and techniques that will be used on future solar space
missions. The purpose of the flight was to improve understanding of
the mechanisms involved in many different types of solar activity,
particularly flares and solar filament eruptions. Achieving this goal
demanded the development of a platform for an 80-cm F/1.5 optical
telescope that would be stable to 10 arcseconds. In addition, we
developed an image motion compensation system capable of holding the
Sun's image to better than the system's 0.2 arcsecond diffraction
limit. Other key elements on board included a lithium-niobate
Fabry-Perot etalon filter to provide a tunable 0.016-nm bandpass over
a wide wavelength range, a fast 1534 X 1024-pixel Kodak CCD camera,
and 180 GBytes of on-board storage. There was also a system for
sending commands and receiving telemetry and a high-speed downlink
for sending images during periods when the payload was in line of
sight of the ground station. On- board computers provided a command
and control system capable of near-autonomous operation. During most
of the flight, contact with the payload was sporadic, so operation
was primarily under autonomous control.

---------------------------------------------------------
Title: Solar Terrestrial Relations Observatory (STEREO)
Authors: Davila, Joseph M.; Rust, David M.; Pizzo, Victor J.; Liewer,
Paulett C.
1996SPIE.2804...34D Altcode:
The solar output changes on a variety of timescales, from minutes,
to years, to tens of years and even to hundreds of years. The
dominant timescale of variation is, of course, the 11-year solar
cycle. Observational evidence shows that the physics of solar output
variation is strongly tied to changes in the magnetic field, and perhaps
the most dramatic manifestation of a constantly changing magnetic
field is the Coronal Mass Ejection (CME). On August 5 - 6, 1996 the
Second Workshop to discuss missions to observe these phenomena from
new vantage points, organized by the authors, was held in Boulder,
Colorado at the NOAA Space Environmental Center. The workshop was
attended by approximately 20 scientists representing 13 institutions
from the United States and Europe. The purpose of the Workshop was
to discuss the different concepts for multi- spacecraft observation
of the Sun which have been proposed, to develop a list of scientific
objectives, and to arrive at a consensus description of a mission to
observe the Sun from new vantage points. The fundamental goal of STEREO
is to discover how coronal mass ejections start at the Sun and propagate
in interplanetary space. The workshop started with the propositions
that coronal mass ejections are fundamental manifestations of rapid
large-scale change in the global magnetic structure of the Sun, that
CME's are a major driver of coronal evolution, and that they may play
a major role in the solar dynamo. Workshop participants developed a
mission concept that will lead to a comprehensive characterization of
CME disturbances through build-up, initiation, launch, and propagation
to Earth. It will also build a clear picture of long-term evolution
of the corona. Participants in the workshop recommended that STEREO
be a joint mission with the European scientific community and that
it consist of four spacecraft: `East' at 1 AU near L4, 60 deg from
EArth to detect active regions 5 days before they can be seen by
terrestrial telescopes. `West' at L5 views the sources of energetic
particle events reaching Earth. `Earth Orbiter' to view the Sun, solar
plasma and Earth's magnetosphere, and `North-South' in a 1 AU orbit
tilted 30 deg from the ecliptic plane to provide measurements of polar
fields and high-latitude activity. All spacecraft will carry solar
activity imagers (e.g., EUV telescope and white-light coronagraph)
and radio burst detectors to support a tomography program. All will
carry sensitive polarimeters that will image CME's from 40 solar radii
to 1 AU, and all will carry instruments for situ plasma and energetic
particle sampling. East and North-South have solar vector magnetographs.

---------------------------------------------------------
Title: A Possible Mechanism Governing the Production and Evolution
of Ellerman Bombs
Authors: Diver, Declan A.; Brown, John C.; Rust, David M.
1996SoPh..168..105D Altcode:
A hydrodynamic-magnetofluid hybrid analysis of lower chromospheric
shear flows in the Sun may explain the occurrence and time development
of Ellerman bombs. The analysis assumes that the erupting material
forming the bomb is driven initially by the Kelvin-Helmholtz fluid
instability applied to the interface between two atmospheric fluid
layers, characterized by a steep density change across the boundary
and driven by flow fields around sunspots. The ensuing instability
eventually evolves into a magnetofluid phenomenon by virtue of the
trapping and bending of the interfacial magnetic field, giving rise
to a dense globule of material entering, and persisting in, the upper
layers and due to Ohmic dissipation having a significantly enhanced
temperature compared with ambient material.

---------------------------------------------------------
Title: Escape of magnetic toroids from the Sun
Authors: Bieber, John W.; Rust, David M.
1996AIPC..382..430B Altcode:
Analysis of heliospheric magnetic fields at 1 AU shows that
1024 Mx of net toroidal flux escapes from the Sun per solar
cycle. This rate is compared with the apparent rate of flux emergence
at the solar surface, and it is concluded that escaping toroids will
remove at least 20% of the emerging flux, and may remove as much as
100% of emerging flux if multiple eruptions occur on the toroids. The
data imply that flux escapes the Sun with an efficiency far exceeding
Parker's upper limit estimate of 3%. Toroidal flux escape is almost
certainly the source of the observed overwinding of the interplanetary
magnetic field spiral. Two mechanisms to facilitate net flux escape
are discussed: helicity charging to push open the fields and flux
transport with reconnection to close them off. We estimate the Sun
will shed ~2×1045 Mx2 of magnetic helicity per
solar cycle, leading to a mean helicity density of 100 Mx2
cm-3 at 1 AU, which agrees well with observations.

---------------------------------------------------------
Title: Helicity conservation in expanding plasmas: Application to
interplanetary magnetic clouds
Authors: Kumar, Ashok; Rust, D. M.
1996AIPC..382..434K Altcode:
Magnetic energy of a plasma, expanding under the constraint of magnetic
helicity conservation, decreases with expansion. Part of this lost
magnetic energy might go into heating the plasma. This is used to
explain the high temperatures observed in interplanetary magnetic clouds
(IMCs). IMCs are modeled as intrinsic-scale flux ropes ejected from the
Sun, and it is assumed that their total magnetic helicity, flux and
mass are conserved during evolution. The temperature of an expanding
cloud goes through a maximum that may be two orders of magnitude higher
than the starting value. The model also provides scaling laws for the
magnetic field strength, temperature, radial size, density, asymmetry
of the magnetic field strength profile, slope of the plasma velocity
profile inside clouds, and plasma beta, as functions of distance from
the Sun which are then compared with the cloud data obtained between
0.3 and 4 AU from the Sun.

---------------------------------------------------------
Title: Interplanetary magnetic clouds, helicity conservation, and
current-core flux-ropes
Authors: Kumar, Ashok; Rust, D. M.
1996JGR...10115667K Altcode:
A current-core flux-rope model for interplanetary magnetic clouds
is presented which explains their average thermodynamic and magnetic
properties. It is assumed that during a magnetic cloud's evolution,
its total magnetic helicity, flux and mass are conserved and that the
dynamics of a cloud is governed by the Lorentz self-force acting on its
curved portions. Total magnetic energy and current in a magnetic cloud
decrease monotonically as it elongates. Part of this magnetic energy
is lost in overcoming solar gravity, part goes into the bulk kinetic
energy, and the rest can be assumed to go into heating the plasma
inside the cloud. Due to this dissipation of magnetic energy as heat,
the temperature of an expanding cloud goes through a maximum before the
cloud leaves the corona. The temperature may reach 1.7×106
K. As a cloud expands into interplanetary space, the total plasma
beta asymptotically approaches a constant value between 0.39 and 0.52,
irrespective of its initial value. Apart from explaining the heating
and expansion of magnetic clouds, this model also provides expressions
(scaling laws) for the magnetic field strength, temperature, radius,
density, asymmetry of the magnetic field strength profile, slope of the
plasma velocity profile inside clouds, and plasma beta, as functions
of distance from the Sun. These theoretical results are compared with
cloud data obtained between 0.3 and 4 AU from the Sun. The comparisons
show a good agreement between observation and theory.

---------------------------------------------------------
Title: Evidence for Helically Kinked Magnetic Flux Ropes in Solar
Eruptions
Authors: Rust, D. M.; Kumar, A.
1996ApJ...464L.199R Altcode:
Images of the X-ray corona near the solar disk's center were examined
for large, transient brightenings of the type known to be associated
with H alpha filament eruptions and coronal mass ejections. Many of the
brightenings were sigmoid (S-shaped). The measured ratios of length to
width of the sigmoid features are shown to be consistent with ratios
predicted by a simple model based on a kinked and twisted magnetic flux
rope. Many of the studied sigmoid brightenings evolved into arcades
of bright loops. Such arcades are often associated with coronal mass
ejections, and it is suggested that the cause of the ejections is an
MHD helical kink instability in the H alpha filament/coronal arcade
complexes. Reverse-S brightenings outnumbered forward-S brightenings
by six to one in the northern hemisphere. Forward-S brightenings were
similarly predominant in the south. This hemispherical segregation
suggests that the magnetic fields in the transient features are
systematically twisted. Globally, the implied distribution of magnetic
helicity is similar to the distribution that Martin et al. discovered
in quiescent H alpha filaments.

---------------------------------------------------------
Title: The Flare Genesis Experiment
Authors: Rust, D. M.; Murphy, G. A.; Strohbehn, K.; Keil, S. L.;
Keller, C. U.
1996AAS...188.6705R Altcode: 1996BAAS...28Q.934R
The goal of the Flare Genesis Experiment is to make solar observations
at the highest practicable resolution in order to improve understanding
of the mechanisms involved in many different types of solar activity,
particularly flares and solar filament eruptions. Achieving this goal
demanded the development of a balloon-borne platform for an 80-cm F/1.5
optical telescope that could maintain 10 arcsec pointing stability. The
first flight of the Flare Genesis Experiment took place in January
1996. In the stratosphere, 37 km above Antarctica, for more than 19
days, the Flare Genesis telescope pointed at the Sun with the planned
stability. While the primary science objective, to measure the vector
magnetic fields using two liquid crystal polarization modulators, was
not achieved on this flight, 18,000 continuum images were obtained. They
demonstrate that the major engineering challenges for such a flight
were overcome. In addition, we developed an image motion compensation
system capable of limiting the motion of the Sun's image on the focal
plane to less than the system's 0.2 arcsec diffraction limit. Other key
elements on board included a lithium-niobate Fabry-Perot etalon filter
to provide a tunable 0.016-nm bandpass over a wide wavelength range,
a 1538 x 1024- pixel CCD camera and 100 GBytes of on-board storage. We
will describe the payload design and how the instruments performed. We
will discuss how the constraints of long duration Antarctic ballooning
guided the final design and impacted the results. Two more flights
are planned before the next solar maximum. Such long-duration balloon
flights provide a relatively inexpensive means to observe the Sun at
the highest resolution and to develop instrumentation and techniques
for future space missions.

---------------------------------------------------------
Title: Origins of Solar Activity
Authors: Rust, David M.
1996jhu..rept.....R Altcode:
Work under the subject grant began in August 1992, when
Mr. J. J. Blanchette began study and data analysis in the area of
solar flare research. Mr. Blanchette passed all requirements toward
a Ph.D., except for the thesis. Mr. Blanchette worked with the
APL Flare Genesis Experiment team to build a balloon-borne solar
vector magnetograph. Other work on the magnetograph was partially
supported by AFOSR grant F49620-94-1-0079. Mr. Blanchette assisted
the Flare Genesis team prepare the telescope and focal plane optical
elements for a test flight. He participated in instrument integ
ration and in launch preparations for the flight, which took place
on January 23, 1994. Mr. Blanchette was awarded a Masters Degree
in Astrophysics by the Johns Hopkins University in recognition of
his achievements. Mr. Blanchette indicated a desire to suspend work
on the Ph.D. degree, and he left the AASERT program on August 31,
1994. Under the guidance of his advisor at JHU/APL, Dr. David M. Rust,
Mr. Blanchette gained enough background in solar physics so that he can
contribute to observational, analytical, and presentation efforts in
solar research. Beginning in August 1995, Mr. Ashok Kumar was supported
by the grant. Mr. Kumar demonstrated remarkable theoretical insight into
the problems of solar activity. He developed the concept of intrinsic
scale magnetic flux ropes in the solar atmosphere and interplanetary
space. His model can explain the heating of interplanetary magnetic
clouds. Recently, his idea has been extended to explain solar
wind heating. If the idea is confirmed by further comparison with
observations, it will be a major breakthrough in space physics and it
may lead to an explanation for why the solar corona's temperature is
over a million degrees.

---------------------------------------------------------
Title: Magnetic Helicity And Its Relationship To The Origins Of
Solar Eruptions
Authors: Rust, D. M.
1996APS..MAY.L1406R Altcode:
From an analysis of solar magnetic fields and of images of the
sun's corona, we may be able to test a novel conjecture that was
advanced by J. B. Taylor to explain the behavior of plasmas in fusion
experiments. The proposed principle of conservation of magnetic
helicity may explain many problems of solar activity, e.g., why there
are solar eruptions, how the solar wind and corona are heated, and
how the solar dynamo functions. Helicity conservation asserts that
coiled magnetic fields, once formed, remain coiled, even as they
undergo the kind of dramatic transformations seen in solar flares
and mass ejections. Helicity conservation may be no less important in
understanding and describing space plasmas than conservation of mass
and magnetic flux. Helicity conservation has not yet been widely used in
solar physics, but recent measurements of helicity on the solar surface
and in the solar wind suggest that application of helicity conservation
could lay the foundation for major advances in understanding the solar
dynamo and magnetic fields throughout the universe.

---------------------------------------------------------
Title: Toroidal Magnetic Fields in the Solar Atmosphere
Authors: Rust, D. M.
1996AAS...188.3508R Altcode: 1996BAAS...28..872R
The recent discovery that filaments in opposite hemispheres of the Sun
tend to exhibit opposite magnetic helicity has prompted a reexamination
of the global properties of solar filaments, photospheric magnetic
fields, and interplanetary magnetic clouds. It is suggested that
observations of East- West asymmetry in high-latitude and mid-latitude
photospheric fields can be explained as measurements of the component
normal to the surface contaminated by a toroidal component. The
toroidal component can also be traced by its effect on chromospheric
fine structure and by measurements of the magnetic field direction
inside and beneath solar filaments. Since filaments frequently erupt
and become interplanetary magnetic clouds, their field direction can
be determined by in situ measurements at 1 AU. These measurements
are consistent with the field results obtained by traditional remote
sensing. The variations in direction of the surface toroidal component
over the past three solar cycles are consistent with those expected
from naive models.

---------------------------------------------------------
Title: Balloon-Borne Polarimetry
Authors: Rust, D. M.; Murphy, G.; Strohbehn, K.; Keller, C. U.
1996SoPh..164..403R Altcode:
For about two weeks in 1995, the balloon-borne Flare Genesis
Experiment will continuously observe the Sun well above the turbulent,
image-blurring layers of the Earth's atmosphere. The polarization-free
80 cm telescope will supply images to a liquid-crystal based vector
magnetograph, which will measure magnetic features at a resolution
of 0.2 arcsec. An electrically tunable lithium-niobate Fabry-Perot
provides a spectral resolution of about 0.015 nm. In a follow-up
series of Antarctic balloon flights, the Flare Genesis Experiment
(FGE) will provide unprecedented details about sunspots, flares,
magnetic elements, filaments, and the quiet solar atmosphere.

---------------------------------------------------------
Title: Helicity Conservation in Expanding Magnetized Plasmas: Flux
Ropes in The Solar Wind
Authors: Kumar, Ashok; Rust, David M.
1996ASPC...95..315K Altcode: 1996sdit.conf..315K
No abstract at ADS

---------------------------------------------------------
Title: Magnetic Helicity, MHD Kink Instabilities and Reconnection
in the Corona
Authors: Rust, D. M.
1996ASPC..111..353R Altcode: 1997ASPC..111..353R
Yohkoh images of the X-ray corona were examined for large transient
brightenings near solar disk center. Many of the brightenings were
sigmoid (S-shaped). Reverse-S brightenings outnumbered forward-S
brightenings by 6 to 1 in the northern hemisphere. Forward-S
brightenings were similarly predominant in the south. This hemispherical
segregation is consistent with the twisting patterns discovered in Hα
filaments, and it suggests that the magnetic fields in the transient
brightenings are also twisted. The ratios of width to length of the
sigmoid brightenings are those of kinked, twisted flux ropes, and it is
suggested that filaments (and coronal mass ejections) erupt because of
MHD helical kink instabilities. This would imply that solar eruptions
are not accidental events. Rather, they result from helicity-conserving
reconnections among fields twisted systematically by helicity-generating
forces of the solar dynamo. Interplanetary field measurements show that
the total magnetic helicity ejected in a solar cycle is of the same
order as the total helicity generated inside the Sun by Coriolis forces.

---------------------------------------------------------
Title: The Escape of Magnetic Flux from the Sun
Authors: Bieber, J. W.; Rust, D. M.
1995ApJ...453..911B Altcode:
Analysis of heliospheric magnetic fields at 1 AU shows that
1024 Mx of net azimuthal flux is ejected by the Sun per
solar cycle. This rate is identified with the rate of toroidal flux
generation. It is compared with indicators of flux ejection from the
solar atmosphere, including coronal mass ejections (CM Es), filament
eruptions, and active region loop expansion. The rate is consistent
with estimates of flux escaping in these phenomena. The toroidal flux
escape rate is compared with the apparent rate of flux emergence at
the solar surface, and it is concluded that escaping toroids will
remove at least 20% of the emerging flux, and probably remove 100%
of emerging flux, since multiple eruptions occur on the toroids. The
data imply that flux escapes the Sun with an efficiency far exceeding
Parker's upper limit estimate of 3 %. Toroidal flux escape is almost
certainly the source of the observed overwinding of the interplanetary
magnetic field spiral. Two mechanisms to facilitate net flux escape are
discussed: helicity charging to push open the fields and flux transport
with reconnection to close them off. We estimate the Sun will shed ∼2
× 1045 Mx2 of magnetic helicity per solar cycle,
leading to a mean helicity density of 100 Mx2 cm-3
at 1 AU, which agrees well with observations. Helicity shedding and
flux escape are seen as essential to the cyclic renewal of the solar
dynamo. It is argued that because lefthanded and right-handed helical
fields accumulate in the northern and southern hemispheres, separately,
conservation of magnetic helicity requires that the dynamo-generated
fields be expelled. The mean lifetime of magnetic flux on the solar
surface is 3-6 months. The mechanisms described here should also enable
Sun-like stars to shed dynamo-generated fields.

---------------------------------------------------------
Title: Escape of magnetic toroids from the Sun
Authors: Bieber, John W.; Rust, David M.
1995sowi.conf...46B Altcode:
Analysis of heliospheric magnetic fields at 1 AU shows that
1024 Mx of net azimuthal flux escapes from the Sun per
solar cycle. This rate is consistent with rates derived from other
indicators of flux escape, including coronal mass ejections and
filament eruptions. The toroidal flux escape rate is compared with
the apparent rate of flux emergence at the solar surface, and it is
concluded that escaping toroids will remove at least 20% of the emerging
flux, and may remove as much as 100% of emerging flux if multiple
eruptions occur on the toroids. The data imply that flux escapes the
Sun with an efficiency far exceeding Parker's upper limit estimate of
3%. Toroidal flux escape is almost certainly the source of the observed
overwinding of the interplanetary magnetic field spiral. Two mechanisms
to facilitate net flux escape are discussed: helicity charging to push
open the fields and flux transport with reconnection to close them
off. We estimate the Sun will shed approximately 2 x 1045
of magnetic helicity per solar cycle, leading to a mean helicity
density of 100 Mx2cm-3 at 1 AU, which agrees
well with observations.

---------------------------------------------------------
Title: Magnetic clouds, helicity conservation, and intrinsic scale
flux ropes
Authors: Kumar, A.; Rust, D. M.
1995sowi.conf...46K Altcode:
An intrinsic-scale flux-rope model for interplanetary magnetic clouds,
incorporating conservation of magnetic helicity, flux and mass is
found to adequately explain clouds' average thermodynamic and magnetic
properties. In spite their continuous expansion as they balloon into
interplanetary space, magnetic clouds maintain high temperatures. This
is shown to be due to magnetic energy dissipation. The temperature
of an expanding cloud is shown to pass through a maximum above its
starting temperature if the initial plasma beta in the cloud is less
than 2/3. Excess magnetic pressure inside the cloud is not an important
driver of the expansion as it is almost balanced by the tension in
the helical field lines. It is conservation of magnetic helicity and
flux that requires that clouds expand radially as they move away
from the Sun. Comparison with published data shows good agreement
between measured cloud properties and theory. Parameters determined
from theoretical fits to the data, when extended back to the Sun,
are consistent with the origin of interplanetary magnetic clouds in
solar filament eruptions. A possible extension of the heating mechanism
discussed here to heating of the solar corona is discussed.

---------------------------------------------------------
Title: Evolution of Solar Filaments into Interplanetary Magnetic
Clouds: Effect of Magnetic Hellcity Conservation
Authors: Kumar, A.; Rust, D. M.
1995SPD....26..305K Altcode: 1995BAAS...27..953K
No abstract at ADS

---------------------------------------------------------
Title: Helicity charging and eruption of magnetic flux from the sun
Authors: Rust, D. M.; Kumar, A.
1994ESASP.373...39R Altcode: 1994soho....3...39R
No abstract at ADS

---------------------------------------------------------
Title: Helical Magnetic Fields in Filaments
Authors: Rust, D. M.; Kumar, A.
1994SoPh..155...69R Altcode:
For both even and odd-numbered solar cycles, right-hand heliform
filaments predominate at middle and high latitudes in the northern
hemisphere while left-handed ones predominate in the south. This recent
discovery has prompted a re-examination of past measurements of magnetic
fields in prominences. This re-examination indicates that Rust (1967),
in his interpretation of solar cycle 20 measurements in terms of the
Kippenhahn-Schlüter model, and Leroy, Bommier, and Sahal-Bréchot
(1984), in their interpretation of solar cycle 21 measurements in
terms of the Kuperus-Raadu model were both misled by the global
pattern of helicity. While the original magnetic field measurements
are consistent with the new results about heliform magnetic fields
in filaments, neither of the well-known classes of two-dimensional
models can produce both the proper axial field direction and the
observed pattern of helicity. A global, subsurface velocity pattern
that would twist the fields before emergence as filaments seems to
be required. In this paper a twisted-flux-rope model consistent with
the new understanding of filament fields is presented. The model is
based on a constant-α solution of the magnetostatic equations, where
electric current densityj(r) =αB(r). The model filament has dimensions
in general agreement with observations. It is shown to be stable if
the length is less than 140 000 km to 1,400 000 km, depending on the
value ofα. The model also provides a new explanation of eruptive
prominences and for the origin of the entrained material.

---------------------------------------------------------
Title: Preflare State
Authors: Rust, David M.; Sakurai, Takashi; Gaizauskas, Victor; Hofmann,
Axel; Martin, Sara F.; Priest, Eric R.; Wang, Jing-Xiu
1994SoPh..153....1R Altcode:
Discussion on the preflare state held at the Ottawa Flares 22
Workshop focused on the interpretation of solar magnetograms and
of Hα filament activity. Magnetograms from several observatories
provided evidence of significant build up of electric currents in
flaring regions. Images of X-ray emitting structures provided a clear
example of magnetic relaxation in the course of a flare. Emerging
and cancelling magnetic fields appear to be important for triggering
flares and for the formation of filaments, which are associated with
eruptive flares. Filaments may become unstable by the build up of
electric current helicity. Examples of heliform eruptive filaments
were presented at the Workshop. Theoretical models linking filaments
and flares are briefly reviewed.

---------------------------------------------------------
Title: Spawning and Shedding Helical Magnetic Fields in the Solar
Atmosphere
Authors: Rust, D. M.
1994GeoRL..21..241R Altcode:
Measurements of the helical fields in interplanetary magnetic clouds
have corroborated recent evidence that the magnetic fields in solar
filaments in the northern and southern hemispheres of the Sun are
preferentially left-handed and right-handed heliform, respectively. In
13 cases out of 16, the chirality of magnetic clouds passing Earth about
4 days after a filament eruption or an eruptive solar flare corresponded
to the predominant chirality in the hemisphere originating the solar
event. Active regions and sunspots also indicate that helicity is
segregated by hemisphere. Torque due to an equatorial jet stream
beneath the photosphere may twist the fields.

---------------------------------------------------------
Title: The flare genesis project
Authors: Rust, D. M.
1994AdSpR..14b..89R Altcode: 1994AdSpR..14...89R
The feasibility of a balloon-borne experiment to understand how
the magnetic fields at the solar surface emerge, coalesce, unravel
and erupt in solar flares was studied. A key component of the Flare
Genesis instrument will be a solar telescope with an 0.8-meter-diameter
lightweight mirror. Effects of pendulation and jitter, gravity and
temperature on the images formed by the telescope were studied to
determine whether it will maintain the desired resolution of ~0.2 sec of
arc at float altitude. The principal conclusions of the study are that
(1)sufficient image stability can be maintained at the focal plane;
(2) polarization sensitivity of 2 × 10-4 is achievable;
and (3) the data system can store ~ 2000 magnetograms on-board in the
course of a 10-to-14-day Antarctic flight.

---------------------------------------------------------
Title: Active Region Development: Results from the JHU/APL Vector
Magnetograph
Authors: Rust, D. M.; Murphy, G.; Balasubramaniam, K. S.; Gullixson,
C. A.; Henry, T.; Coulter, R. L.; Keil, S. L.
1994ASPC...68..263R Altcode: 1994sare.conf..263R
No abstract at ADS

---------------------------------------------------------
Title: Are Flares Necessary?
Authors: Rust, D. M.
1994ASPC...68..335R Altcode: 1994sare.conf..335R
No abstract at ADS

---------------------------------------------------------
Title: A Correlation Between Sunspot Whirls and Filament Type
Authors: Rust, D. M.; Martin, S. F.
1994ASPC...68..337R Altcode: 1994sare.conf..337R
No abstract at ADS

---------------------------------------------------------
Title: A Biologically-Inspired Image Position Sensor
Authors: Strohbehm, K.; Rust, D.; Andreou, A.; Jenkins, R.
1993rtpf.conf...32S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Continued development of an ultra-narrow bandpass filter for
solar research
Authors: Rust, David M.
1993jhu..reptS....R Altcode:
The objective of work under this task was to develop ultranarrow optical
bandpass filters and related technology necessary for construction
of a compact solar telescope capable of operating unattended in
space. The scientific problems to which such a telescope could
be applied include solar seismology, solar activity monitoring,
solar irradiance variations, solar magnetic field evolution, and the
location of targets for narrow-field specialized telescopes. We have
demonstrated a Y-cut lithium-niobate Fabry-Perot etalon. This filter
will be used on the Flare Genesis Experiment. We also obtained solar
images with a Z-cut etalon. The technical report on etalon filters is
attached to this final report. We believe that work under this grant
will lead to the commercial availability of a universal optical filter
with approximately 0.1 A bandwidth. Progress was made toward making
a suitable 1-2 A tunable blocker filter, but it now appears that the
best approach is to make a double-cavity etalon that will not require
such a narrow blocker. Broader band blockers are commercially available.

---------------------------------------------------------
Title: Origins of solar activity. First year report, AASERT grant
Authors: Rust, David M.
1993jhu..reptR....R Altcode:
This report describes the first year of training and progress of
Mr. J.J. Blanchette toward a Ph.D. in Physics, with specialization
in Solar Physics. Mr. Blanchette has met all academic requirements
in order to proceed with his thesis research. He is a full-time
graduate research fellow, and he has gained a good background in
solar activity research. He has taken on the task of implementing the
focal-plane functions of the Target Selector Telescope of the Flare
Genesis Experiment, a balloon-borne telescope for solar activity
research. During the report period, Mr. Blanchette presented a
description of his work on solar active region NOAA 7260 at the 24th
meeting of the Solar Physics Division of the AAS.

---------------------------------------------------------
Title: Vector Magnetography of a Large Sunspot
Authors: Rust, D. M.; Murphy, G. A.; Blanchette, J. J.; Cauzzi, C.;
Keil, S.; Balasubramaniam, K. S.
1993BAAS...25.1205R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: It's the Helicity, Stupid!
Authors: Rust, D. M.
1993BAAS...25.1225R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Solar vector magnetic field research
Authors: Rust, David M.
1993jhu..reptQ....R Altcode:
The objective of the project was to measure the magnetic fields in
solar active regions, develop methods for predicting solar flares on
the basis of the measurements, and improve the instrumentation for solar
magnetic field measurements. In cooperation with the staff at the Solar
Branch of the USAF Phillips Laboratory, field measurements were made
almost daily during the grant period. The principal result of analyses
carried out so far is that so-called sheared magnetic fields are neither
necessary nor sufficient for solar flaring. The crucial element seems
to be emerging magnetic flux and local development of shear in the
hour before flare onset. A need for greatly improved instrumentation
was identified. A new vector magnetograph was designed for operation
above the image-degrading layers of the atmosphere. Fourteen technical
publications and presentations appeared under grant sponsorship.

---------------------------------------------------------
Title: Origins and effects of solar flares
Authors: Rust, D. M.
1993beps.proc...73R Altcode:
During the 1989 - 1991 peak of solar activity, geomagnetic storms from
interplanetary shocks caused a massive failure in the Canadian power
grid, minor failures in other power eqipment, and many communications
disruptions and satellite malfunctions. The proton storms would have
been lethal for unshielded space travellers. Had the power managers
been given a credible, timely forecast of the solar storm, they could
have protected their generating equipment and the grid. They do not keep
protective circuits in place full-time because that reduces efficiency
and increases the cost of power distribution. Nor will astronauts on
the moon or in deep space confine themselves full-time to thick-walled,
radiation-resistant closets. To enable manned deep space exploration
we have to find a way to determine what happens in solar flares. Only
this will improve the forecasts. Expensive and restrictive protective
measures would then have to be applied only when a major flare is
clearly imminent. There is no generally accepted flare theory or
description of the pre-flare state or of the instabilities. The Solar
Maximum Mission (SMM) cleared up many questions about electromagnetic
flare emissions and the structure of the flaring atmosphere, but the
dynamic of the magnetic fields is still a mystery.

---------------------------------------------------------
Title: Plasma, magnetic, and electromagnetic measurements at
nonmagnetic bodies.
Authors: Rust, D. M.; Kumar, A.; Thompson, K. E.
1993atpi.workR..20R Altcode:
A new type of image detector will simultaneously analyze the
polarization of light at all picture elements in a scene. The integrated
Dual Imaging Detector (IDID) consists of a polarizing beam splitter
bonded to a charge-coupled device (CCD), with signal-analysis circuitry
and analog-to-digital converters, all integrated on a silicon chip. The
polarizing beam splitter can be either a Ronchi ruling, or an array
of cylindrical lenslets, bonded to a birefringent wafer. The wafer, in
turn, is bonded to the CCD so that light in the two orthogonal planes of
polarization falls on adjacent pairs of pixels. The use of a high-index
birefringent material, e.g., rutile, allows the IDID to operate at
f-numbers as high as f/3.5. Other aspects of the detector are discussed.

---------------------------------------------------------
Title: Solar flare prediction needed
Authors: Rust, D.
1993EOSTr..74..553R Altcode:
“From veils of haze now comes the gleam, Here to a tender scarf
it tapers, Here gushes forth a vivid stream; Then threads of light
in a network surging Their silver veins through valleys run, Till,
gathered by the hills converging, The sundered filaments are one.”

---------------------------------------------------------
Title: Solar flares: An overview
Authors: Rust, David M.
1992AdSpR..12b.289R Altcode: 1992AdSpR..12..289R
This is a survey of solar phenomena and physical models that may be
useful for improving forecasts of solar flares and proton storms
in interplanetary space. Knowledge of the physical processes that
accelerate protons has advanced because of gamma-ray and X-ray
observations from the Solar Maximum Mission telescopes. Protons are
accelerated at the onset of flares, but the duration of any subsequent
proton storm at 1 AU depends on the structure of the interplanetary
fields. X-ray images of the solar corona show possible fast proton
escape paths. Magnetographs and high-resolution visible-band images
show the magnetic field structure near the acceleration region and the
heating effects of sunward-directed protons. Preflare magnetic field
growth and shear may be the most important clues to the physical
processes that generate high energy solar particles. Any dramatic
improvement in flare forecasts will require high resolution solar
telescopes in space. Several possibilities for improvements in the art
of flare forecasting are presented, among them: the use of acoustic
tomography to probe for subsurface magnetic fields; a satellite-borne
solar magnetograph; and an X-ray telescope to monitor the corona
for eruptions.

---------------------------------------------------------
Title: A Search for Polarization in Ellerman Bombs
Authors: Rust, David M.; Keil, Steven L.
1992SoPh..140...55R Altcode:
Ellerman bombs, also called `moustaches', are transient brightenings at
tiny (&lt; 1 arc sec) points in the lower chromosphere whose spectra
are characterized by elongated emission wings on the hydrogen Balmer
lines. Babin and Koval recently found linear polarization as high as
20% in bombs, but no physical process that could produce such a high
degree of polarization was suggested. A new observational study of
polarization in Ellerman bombs is reported here. Images of 32 bombs
were obtained with a digital video system viewing the Sun through a
6 Å filter at the Sacramento Peak Vacuum Tower Telescope. A novel
polarizing beamsplitter divided each image into two interleaved
polarized components which passed simultaneously through a single set
of optics and were separated only during data analysis. The sensitivity
threshold of the measurements was ∼ 1%. In 4 cases out of 32, linear
polarization above 2% was detected. The higher incidence of &gt; 2%
polarization reported by Babin and Koval is not confirmed.

---------------------------------------------------------
Title: Variation of the Vector Magnetic Field in an Eruptive Flare
Authors: Rust, D. M.; Cauzzi, G.
1992LNP...399...46R Altcode: 1992esf..coll...46R; 1992IAUCo.133...46R
Observations of a 3B, M6 flare on April 2, 1991 appear to confirm
earlier evidence that eruptive flares are triggered by measurable
magnetic field changes. In the eight hours before the flare, the
shear in the magnetic fields increased. The development that likely
triggered the flare was the emergence into the active region and rapid
proper motion of new flux. One of the small spots marking the negative
magnetic leg of the new flux pushed into an established positive field
at 0.2 km/s. Data from the JHU/APL vector magnetograph show that this
motion led to the development of a sheared field. The flare started
near the newly-sheared fields and spread to engulf most of the spot
region. A magnetogram taken 45 min after flare onset shows possible
relaxation of the sheared fields.

---------------------------------------------------------
Title: A biologically-inspired VSLI sunspot tracker.
Authors: Rust, D. M.; Strohbehn, K.
1992BAAS...24.1075R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Solar vector magnetic field research
Authors: Rust, David M.
1991jhu..rept.....R Altcode:
Observations have been made before and after a large solar
flare. Magnetic features were observed that could be used to predict
flares if they are a regular feature of such events. The observations
were among the first to show the development of shear within one hour
of flare onset. Observations of linear polarization have been made of
transient brightenings at small points in the lower chromosphere. The
association between these flare-like events and magnetic fields has
been studied. A feasibility study has been made of observing the sun
with a balloon-borne vector magnetograph. The APL vector magnetograph
developed under an OSR URI is operational.

---------------------------------------------------------
Title: New instruments for solar research.
Authors: Rust, D. M.; O'Byrne, J. W.; Sterner, R. E., II
1991JHATD..11...77R Altcode:
New instruments have been installed at observatories in New Mexico
and California for measuring solar magnetic fields and surface
velocities. The magnetic fields provide the enrgy for all eruptive and
accelerative processes on the Sun, and the surface velocities reveal
the dynamics of the solar interior. The new instruments incorporate
several technical innovations, including a lithium niobate filter
for high spectral resolution. With this filter, circular and linear
polarization and Doppler shifts are measured in solar spectral lines to
yield estimates of the magnetic field vector in active sunspot regions.

---------------------------------------------------------
Title: A New Method for Calibrating Vector Magnetograms
Authors: Cauzzi, G.; Rust, D. M.; O'Byrne, J. W.
1991BAAS...23R1054C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: A Search for Polarization in Ellerman Bombs
Authors: Rust, D. M.; Keil, S. L.
1991BAAS...23R1029R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Vector magnetography.
Authors: Rust, D. M.; O'Byrne, J. W.
1991sopo.work...74R Altcode:
Development of the JHU/APL vector magnetograph (VMG) at the National
Solar Observatory gives insight into the advantages and drawbacks of
trying to infer solar active region magnetic fields from filtergram
measurements with 0.8 - 3.0 arcsec spatial resolution, several-minute
temporal resolution and 120 - 180 mÅ spectral resolution. The use of a
narrow-band filter and the weak-field approximation (WFA) of the Stokes
profiles gives good temporal and spatial data on magnetic fields, but
sacrifices information on the thermodynamic parameters. A model of the
VMG's response in the wings of the Ca I line at 6122 Å shows that the
range of validity of the WFA can be extended to 4000 G. It also shows
that the response of the VMG is insensitive to the Doppler shifts due
to the motions (&lt;1 km/s) exhibited by most solar features. The role
of vector magnetography with a narrow-band filter in flare research
is emphasized and several examples of early observations with the VMG
are given.

---------------------------------------------------------
Title: The Earth's climate and variability of the Sun over recent
millennia: Geophysical, astronomical and archaeological aspects
Authors: Rust, D. M.
1991EOSTr..72..157R Altcode:
At the outer limits of the range of topics covered in these proceedings
from a joint meeting of the British Royal Society and the French
Academie des Sciences lie speculation and inaccessible places and
times. The causes of the Sun's variability are hidden beneath its
surface, and we can only speculate about whether solar magnetism,
which provides the energy for the variations, is generated just below
the surface or is a remnant of an ancient magnetism trapped in the
core. An equally distant and inaccessible sphere is the gassy envelope
around the prehistoric Earth where changes in climate presumably drove
early man to alter his habits and homes. But as P. I. Kuniholm writes
in this volume, climate change has often been appealed to in accounting
for phenomena that cannot otherwise be accounted for. Archaeologists
never imagined that physicists would try to reconstruct the Sun's
past from such speculations. Between the two extremes of ignorance,
however, a solid foundation is being built for a scientific account
of the Sun's role in climate change.

---------------------------------------------------------
Title: Sociology of the SMY
Authors: Rust, David M.
1991AdSpR..11e.123R Altcode: 1991AdSpR..11..123R
No abstract at ADS

---------------------------------------------------------
Title: Etalon filters.
Authors: Rust, D. M.
1991LFTR...50.....R Altcode:
This article begins with a brief introduction to Fabry-Perot
interferometers and goes on to describe the use of Fabry-Perot etalons
as narrow-band filters. Properties of solid etalons with fused silica,
mica and lithium niobate substrates are discussed and compared with
those of the Lyot birefringent filter. Examples of applications of
etalon filters in helioseismology, high-resolution imaging and vector
magnetography are given. It is concluded that lithium niobate etalons
can meet the LEST requirements for a universally tunable narrow-band
filter.

---------------------------------------------------------
Title: New instruments for solar research
Authors: Rust, David M.; O'Byrne, John W.; Sterner, Raymond E., II
1990JHATD..11...77R Altcode:
In fulfilment of its goal to develop early detection and warning of
emerging solar magnetic fields, the Center for Applied Solar Physics
(CASP) has designed and constructed a solar vector magnetograph (VMG)
that will provide unique data on the sunspot regions where flares
originate. The instrument is reportedly beginning to approach its goals
of measuring all three components of the solar magnetic field with a
sensitivity of 50 to 100 G and a spatial resolution on the sun of about
700 km (1 arcsec). Importance of new high-resolution capabilities is
stressed and the interpretation of VMG measurements is discussed. The
performance of the solar VMG, installed in a 6-m dome at the National
Solar Observatory at Sacramento Peak in Sunspot, New Mexico, and its
construction and environment are described; particular attention
is given to the use and function of the filters. Initial results
are examined, including a description and analysis of a magnetogram
obtained after installation of an improved blocking filter.

---------------------------------------------------------
Title: Activities and accomplishments of the Center for Applied
Solar Physics, 1987 - 1990
Authors: Rust, David M.
1990jhu..reptQ....R Altcode:
New instruments have been installed at observatories in New Mexico
and California for measuring solar magnetic fields and surface
velocities. The magnetic fields provide the energy for all eruptive
and accelerative processes on the Sun, and the surface velocities
reveal the dynamics of the solar interior. Early detection of emerging
magnetic fields may give several hours' warning of impending solar
flares and interplanetary shocks. The new instruments incorporate
several technical innovations, including lithium niobate filter
for high spectral resolution. With this filter, circular and linear
polarization and Doppler shifts are measured in solar spectral lines
to yield estimates of the magnetic field vector in active sunspot
regions. A program of daily measurements is planned for study of the
current peak in the 11-year solar cycle.

---------------------------------------------------------
Title: Emerging Flux Model of Solar Filament Formation
Authors: Cheng, A. F.; Rust, D. M.
1990BAAS...22..900C Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Vector Magnetic Field Observations in Solar Active Regions
Authors: Rust, D. M.; O'Byrne, J. W.
1990BAAS...22..808R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Doppler-shifted Emission from Helium Ions Accelerated in
Solar Flares
Authors: Peter, Th.; Ragozin, E. N.; Urnov, A. M.; Uskov, D. B.;
Rust, D. M.
1990ApJ...351..317P Altcode:
This paper concerns the Doppler-shifted Ly-alpha radiation emitted by
He II (304 A) in ion beams accelerated in solar flares downward from
the solar corona into the chromosphere, where they are slowed down
and finally stopped. It is found that the radiation from He II ions
with E(0) greater than or equal to 150 keV/amu initially at the top
of the atmosphere would lie typically one order of magnitude above
the background. The radiation from He ions moving initially with E(0)
greater than or equal to 400 keV/amu should be observable as long as
the beam is driven by the flare. Radiative electron capture provides
an effective cooling mechanism.

---------------------------------------------------------
Title: Recent Progress with the JHU/APL Solar Vector Magnetograph
Authors: O'Byrne, J. W.; Rust, D. M.; Sterner, R. E.
1990BAAS...22..816O Altcode:
No abstract at ADS

---------------------------------------------------------
Title: A low polarization solar vector magnetograph.
Authors: Rust, D. M.; O'Byrne, J. W.
1990SPIE.1166..368R Altcode:
A new instrument for measuring magnetic fields in the sun's atmosphere
has recently been installed at the National Solar Observatory in
New Mexico. At each point within the field of view, it detects both
linear and circular polarization in a spectral line from which the
solar magnetic field strength and direction may be deduced. The
vector magnetograph has low instrumental polarization and low
circular-to-linear crosstalk. Spectral resolution is provided by a solid
lithium-niobate Fabry-Perot filter which may be electrically tuned to
scan any solar spectral line. The instrument is capable of 0.7″spatial
resolution and 0.015 nm spectral resolution. The instrument and its
background are described, together with some test results.

---------------------------------------------------------
Title: Performance of the JHU/APL Solar Vector Magnetograph
Authors: Rust, D. M.; O'Byrne, J. W.; Sterner, R. E.
1989BAAS...21.1186R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: High resolution vector magnetograph
Authors: Rust, D. M.; O'Byrne, J.
1989hsrs.conf..378R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The JHU/APL Vector Magnetograph
Authors: O'Byrne, J. W.; Rust, D. M.; Harris, T.
1989BAAS...21..849O Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Review of Recent Solar Magnetic Field Observations
Authors: Rust, D. M.
1989BAAS...21Q.854R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Chromospheric explosions.
Authors: Doschek, G. A.; Antiochos, S. K.; Antonucci, E.; Cheng,
C. -C.; Culhane, J. L.; Fisher, G. H.; Jordan, C.; Leibacher, J. W.;
MacNiece, P.; McWhirter, R. W. P.; Moore, R. L.; Rabin, D. M.; Rust,
D. M.; Shine, R. A.
1989epos.conf..303D Altcode:
The work of this team addressed the question of the response and
relationship of the flare chromosphere and transition region to the
hot coronal loops that reach temperatures of about 107K
and higher. Flare related phenomena such as surges and sprays were
also discussed. The team members debate three main topics: 1) whether
the blue-shifted components of X-ray spectral lines are signatures of
"chromospheric evaporation"; 2) whether the excess line broadening of UV
and X-ray lines is accounted for by "convective velocity distribution"
in evaporation; and 3) whether most chromospheric heating is driven by
electron beams. These debates illustrated the strengths and weaknesses
of our current observations and theories.

---------------------------------------------------------
Title: An optical instrument for measuring solar magnetism.
Authors: Rust, David M.; O'Byrne, John W.; Harris, Terry J.
1988JHATD...9..349R Altcode:
A new instrument for measuring solar magnetic fields, the solar vector
magnetograph, is under construction at APL's Center for Applied Solar
Physics. Its key attributes are high spatial resolution, high optical
throughput, fine spectral selectivity, and ultra-low instrumental
polarization.

---------------------------------------------------------
Title: The stable solar analyzer.
Authors: Rust, D. M.; Appourchaux, T.
1988ESASP.286..227R Altcode: 1988ssls.rept..227R
This paper presents a progress report on the development of an
instrument with very high (1:1010) wavelength stability
designed to measure solar surface velocities and magnetic fields. The
instrument determines Doppler and Zeeman shifts in solar spectral lines
by a 6-point weighted average. It is built around an electrically
tunable solid lithium-niobate Fabry-Perot etalon that is stabilized
against a diode laser which itself is locked to a resonance line
of cesium 133. Key features are the unique etalon, which acts as a
wide-angle 0.017-nm solar filter, the camera with a specially stabilized
shutter, and the instrument control and data collection system. Use
of the instrument in helioseismological research is emphasized.

---------------------------------------------------------
Title: Solar vector magnetograph for Max 1991 programs
Authors: Rust, D. M.; Obyrne, J. W.; Harris, T. J.
1988fnsm.work..113R Altcode:
An instrument for measuring solar magnetic fields is under
construction. Key requirements for any solar vector magnetograph
are high spatial resolution, high optical throughput, fine
spectral selectivity, and ultralow instrumental polarization. An
available 25 cm Cassegrain telescope will provide 0.5 arcsec spatial
resolution. Spectral selection will be accomplished with a 150 mA
filter based on electrically tunable solid Fabry-Perot etalon. Filter
and polarization analyzer design concepts for the magnetograph are
described in detail. The instrument will be tested at JHU/APL, and
then moved to the National Solar Observatory in late 1988. It will be
available to support the Max 1991 program.

---------------------------------------------------------
Title: Solar Vector Magnetograph for Max'91 Programs
Authors: Rust, D. M.; O'Byrne, J. W.; Harris, T. J.
1988BAAS...20..912R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Performance of a Stabilized Fabry-Perot Solar Analyzer
Authors: Rust, D. M.; Appourchaux, T.; Hill, F.
1988IAUS..123..475R Altcode:
A unique solar lineshift analyzer described by Rust, Burton and Leistner
(1986) has been used to study solar oscillations. Operation of this
"Stabilized Solar Analyzer" depends on the electro-optic effect in
crystalline lithium niobate, the substrate of the solid Fabry-Perot
etalon. For 10 days in February, 1986, at the Vacuum Tower Telescope
of the Sacramento Peak Observatory, the authors obtained full-disk
observations of the solar oscillations.

---------------------------------------------------------
Title: Rotation in the Solar Convection Zone Inferred from Fabry-Perot
Observations of the 5-MIN Oscillations
Authors: Hill, F.; Rust, D. M.; Appourchaux, T.
1988IAUS..123...49H Altcode:
Full disk observations of the 5-min solar oscillations have been
obtained with a lithium niobate Fabry-Perot filter. The equatorial
solar rotation rate as a function of depth has been inferred from the
sectoral modes of oscillation using the Backus-Gilbert optimal averaging
inversion method. The results show a rotation rate that slowly decreases
over the depths of 15 to 56 Mm below the photosphere. The results are
in agreement with the previous Duvall-Harvey observations.

---------------------------------------------------------
Title: Highlights of the Study of Energy Release in Flares
Authors: Rust, D. M.; Batchelor, D. A.
1987SoPh..114..399R Altcode:
From February 26 to March 1, 1979, thirty-two solar flare investigators
attended a workshop at Cambridge, Mass., to define objectives and devise
a scientific program for the Study of Energy Release in Flares (SERF)
during the coming solar maximum. Herein we review some major results
of the ensuing five-year effort to observe and understand the flare
energy release process and its effects (energetic particle production,
coronal and chromospheric heating, electromagnetic radiations, and mass
motions and ejections). The central issue — what processes store and
release the energy liberated in flares — remains unresolved except
in the most general terms (e.g., it is generally agreed that the
energy is stored in sheared or stressed magnetic fields and released
by field annihilation during some MHD instability). Resolving that
issue s still one of the most important goals in solar physics, but
the advances during the SERF program have brought it closer.

---------------------------------------------------------
Title: Electrooptic Fabry-Perot filter: development for the study
of solar oscillations
Authors: Burton, C. H.; Leistner, A. J.; Rust, D. M.
1987ApOpt..26.2637B Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Observations of Solar Oscillations with a Fabry-Perot Etalon
Authors: Rust, D. M.; Hill, F.; Appourchaux, T.
1987BAAS...19R.933R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: X-Ray Image of Solar Flares from the Solar Maximum Mission
Authors: Batchelor, D. A.; Rust, D. M.
1987sman.work..289B Altcode:
Sequences of X-ray images of solar flares, obtained with the Hard X-ray
Imaging Spectrometer (HXIS) on the SMM spacecraft, reveal interesting
dynamical phenomena. The authors present here a preliminary analysis of
the events as a group, and discuss some new aspects of the well-studied
1980 May 21 flare and a 1980 November 6 flare.

---------------------------------------------------------
Title: The Sun's spots and flares.
Authors: Rust, David M.
1987swe..conf....2R Altcode:
Recently, a NASA satellite has not only gathered much new information
about sunspots and flares, but it also has had the unique experience of
being repaired in outer space by astronauts. What has been accomplished
with the telescopes of the satellite observatory, and what do solar
physicists hope to achieve with it in the near future?Contents:
Introduction. The repair mission. Research highlights. Gamma rays. X
rays. Ultraviolet rays. Mass ejection. The solar constant.

---------------------------------------------------------
Title: Development of ultrastable filters and lasers for solar
seismology.
Authors: Rust, D. M.; Kunski, R.; Cohn, R. F.
1986JHATD...7..209R Altcode:
The Stable Solar Analyzer is a recently developed instrument for the
measurement of solar magnetic fields and surface velocities that
is being employed at the U.S. National Solar Observatory to study
the subsurface convection cells of the sun and the structure of
surface and subsurface magnetic fields. The Analyzer is expected to
ultimately be flown aboard such spacecraft as the ESA/NASA Solar and
Heliospheric Observatory. This instrument is based on a crystalline
lithium niobate Fabry-Perot filter that is used in conjunction with
a stabilized laser that furnishes an absolute wavelength reference;
this laser Fabry-Perot combination has achieved wavelength stabilities
of the order of 2 parts in 10 to the 10th, over a six-hour interval.

---------------------------------------------------------
Title: A tunable, solid, Fabry-Perot etalon for solar seismology.
Authors: Rust, David M.; Burton, Clive H.; Leistner, Achim J.
1986SPIE..627...39R Altcode:
A solid etalon has been designed and fabricated from a 50-mm diameter
wafer of optical-quality lithium niobate. The finished etalon has
a free spectral range of 0.325 nm at 588 nm. The parallel faces are
coated with silver, and the central 15-mm aperture of the etalon has
a finesse of 18.6. The reflective faces double as electrodes, and
application of voltage will shift the passband. This feature was used
in a servo circuit to stabilize the passband against temperature and
tilt-induced drifts to better than three parts in one billion. Operated
in the stabilized mode for day-long sessions, this filter alternately
samples the wings of a narrow atomic absorption line in the solar
spectrum and produces a signal proportional to velocity on the solar
disk. The Fourier transform of this signal yields information on
acoustic waves in the solar interior.

---------------------------------------------------------
Title: Chromospheric explosions.
Authors: Doschek, G. A.; Antiochos, S. K.; Antonucci, E.; Cheng,
C. -C.; Culhane, J. L.; Fisher, G. H.; Jordan, C.; Leibacher, J. W.;
MacNiece, P.; McWhirter, R. W. P.; Moore, R. L.; Rabin, D. M.; Rust,
D. M.; Shine, R. A.
1986NASCP2439....4D Altcode:
The work of this team addressed the question of the response and
relationship of the flare chromosphere and transition region to the
hot coronal loops that reach temperatures of about 107K
and higher. Flare related phenomena such as surges and sprays are
also discussed. The team members debated three main topics: 1. whether
the blue-shifted components of X-ray spectral lines are signatures of
"chromospheric evaporation"; 2. whether the excess line broadening of UV
and X-ray lines is accounted for by "convective velocity distribution"
in evaporation; and 3. whether most chromospheric heating is driven
by electron beams.

---------------------------------------------------------
Title: Flare surge event of 7 November 1980.
Authors: Sotirovski, P.; Simon, G.; Rust, D. M.
1986lasf.conf...71S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: White light flares and atmospheric modeling (Working Group
report).
Authors: Machado, M. E.; Avrett, E. H.; Falciani, R.; Fang, C.;
Gesztelyi, L.; Henoux, J. -C.; Hiei, E.; Neidig, D. F.; Rust, D. M.;
Sotirovski, P.; Svestka, Z.; Zirin, H.
1986lasf.conf..483M Altcode:
The authors give a short summary of their discussions, and a set
of recommendations which may help in the study of white light flare
emission processes.

---------------------------------------------------------
Title: Influence of Solar Flares on the X-Ray Corona
Authors: Rust, D. M.; Batchelor, D. A.
1986ASSL..123...93R Altcode: 1986shtd.symp...93R
Sequences of X-ray images of solar flares, obtained with the Hard X-ray
Imaging Spectrometer (HXIS) on the SMM spacecraft, reveal many dynamical
phenomena. Movies of 20 flares recorded with 6-sec time resolution were
examined. The authors present a preliminary analysis of the events as
a group, and discuss some new aspects of the well-studied 1980 May 21
flare and a 1980 November 6 flare.

---------------------------------------------------------
Title: On the causes of white-light flares.
Authors: Rust, David M.
1986lasf.conf..282R Altcode: 1986lasf.symp..282R
White-light flares generally exhibit two distinct phases, the impulsive
and the main phase. Spectral characteristics of the optical and X-ray
emissions associated with these two phases are reviewed. Events that
show no Balmer discontinuity or only a small one during the main
phase are examined in detail. It is concluded that intense 1 - 10 Å
X-ray emission may heat the upper photosphere sufficiently to produce
H- continuum emission. The effects of a high-temperature,
high-pressure coronal flare plasma upon the chromosphere and photosphere
are examined with the aid of recent model atmosphere calculations. It is
concluded that white-light flares lacking Balmer discontinuities are due
to the extreme narrowing of the chromosphere under the high-temperature
and high-pressure conditions prevailing in flares rated M5 and above
on the GOES X-ray scale.

---------------------------------------------------------
Title: Evidence for and against electron beams in solar flares.
Authors: Brown, J. C.; Rust, D.
1986lasf.conf..431B Altcode: 1986lasf.symp..431B
The theoretical and observational evidence for the interpretation
of hard X-ray bursts as non-thermal bremsstrahlung from a
collision-dominated thick target electron beam is reviewed critically
as on this interpretation rests the extensive work being done on beam
heating of solar flares. It is concluded that the thick target model
cannot be rejected but that it poses a number of problems too serious
to be lightly dismissed.

---------------------------------------------------------
Title: Multiwavelength Analysis of a Well Observed Flare from Solar
Maximum Mission
Authors: MacNeice, P.; Pallavicini, R.; Mason, H. E.; Simnett, G. M.;
Antonucci, E.; Shine, R. A.; Rust, D. M.; Jordan, C.; Dennis, B. R.
1985SoPh...99..167M Altcode:
We describe and analyse observations of an M1.4 flare which began at 17:
00 UT on 12 November, 1980. Ground based Hα and magnetogram data have
been combined with EUV, soft and hard X-ray observations made with
instruments on-board the Solar Maximum Mission (SMM) satellite. The
preflare phase was marked by a gradual brightening of the flare site
in Ov and the disappearance of an Hα filament. Filament ejecta were
seen in Ov moving southward at a speed of about 60 km s−1,
before the impulsive phase. The flare loop footpoints brightened in Hα
and the CaXIX resonance line broadened dramatically 2 min before the
impulsive phase. Non-thermal hard X-ray emission was detected from the
loop footpoints during the impulsive phase while during the same period
blue-shifts corresponding to upflows of 200-250 km s−1
were seen in Ca XIX. Evidence was found for energy deposition in both
the chromosphere and corona at a number of stages during the flare. We
consider two widely studied mechanisms for the production of the high
temperature soft X-ray flare plasma in the corona, i.e. chromospheric
evaporation, and a model in which the heating and transfer of material
occurs between flux tubes during reconnection.

---------------------------------------------------------
Title: Analysis of a White Light Flare Spectrum
Authors: Boyer, R.; Sotirovsky, P.; Machado, M. E.; Rust, D. M.
1985SoPh...98..255B Altcode:
The continuum emission of an X1 flare on 26 March,
1970 observed close to the solar limb (N 05 E 64) was analyzed by a
photometric determination of the contrast ΔI(λ)/I0(λ)
in the wavelength range 3558-5920 Å. Two possible mechanisms for the
emission were investigated, namely hydrogen Paschen and H−
continua. We show the unlikeness of the Paschen possibility and derive
strong constraints on the temperature structure and energy deposition
mechanism imposed by the H− continuum process.

---------------------------------------------------------
Title: A Fabry-Perot Etalon for Differential Spectral Imaging
Authors: Rust, D. M.; Burton, C.; Abell, R.
1985BAAS...17..642R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Survey of Solar X-Ray Flare Dynamics
Authors: Batchelor, D. A.; Rust, D. M.
1985BAAS...17..628B Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Some design considerations for a satellite-borne magnetograph.
Authors: Rust, D. M.
1985NASCP2374..141R Altcode:
This paper reviews the design criteria for a compact magnetograph that
can monitor solar magnetic fields from a free-flying satellite for 5 -
10 years.

---------------------------------------------------------
Title: Observational evidence for thermal wave fronts in solar flares
Authors: Rust, D. M.; Simnett, G. M.; Smith, D. F.
1985ApJ...288..401R Altcode:
Images in 3.5-30 keV X-rays obtained during the first few minutes of
seven solar flares show rapid motions. In each case X-ray emission first
appeared at one end of a magnetic field structure, and then propagated
along the field at a velocity between 800 and 1700 km/s. The observed
X-ray structures were 45,000-230,000 km long. Simultaneous H-alpha
images were available in three cases; they showed brightenings when
the fast-moving fronts arrived at the chromosphere. The fast-moving
fronts are interpreted as electron thermal conduction fronts since their
velocities are consistent with conduction at the observed temperatures
of 1-3 x 10 to the 7th K. The inferred conductive heat flux of up to
10-billion ergs/s sq cm accounts for most of the energy released in
the flares, implying that the flares were primarily thermal phenomena.

---------------------------------------------------------
Title: New Materials Applications in Solar Spectral Analysis
Authors: Rust, D. M.
1985AuJPh..38..781R Altcode:
The use of lithium niobate and liquid crystals in solar instrumentation
designed for automatic measurement of spectral line shifts is
described. A solid Fabry-Perot etalon of lithium niobate has an
acceptance angle 5.3 times greater than an air-spaced Fabry-Perot
filter for the same allowed passband broadening, and the lithium niobate
device has no moving parts. The use of liquid crystals in Zeeman-effect
analysers is also described. Progress toward implementation of devices
with lithium niobate and liquid crystals in a solar telescope is
described.

---------------------------------------------------------
Title: Fast-Moving Fronts in Solar Flare Loops
Authors: Rust, D. M.
1985spit.conf.1073R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Permanent Changes in Filaments Near Solar Flares
Authors: Rust, D. M.
1984SoPh...93...73R Altcode:
High resolution Hα images obtained before and after 57 importance 1N
or larger flares have been examined for changes in the magnetic fields
(B⊥) transverse to the line of sight. It was assumed
that Hα chromospheric structures outline B⊥. In 37%
of the cases, there was a reconfiguration of segments of filaments
or of chromospheric fibrils. Examination of data from 21 non-flare
intervals shows such changes in 24% of cases. When changes of any
kind, including total disappearance and length changes, are included,
the proportions for flare and non-flare intervals increase to 58% and
52%, respectively. It is concluded that flares do not cause enduring
magnetic field changes in the chromosphere.

---------------------------------------------------------
Title: Flare Loops Heated by Thermal Conduction
Authors: Rust, D. M.; Somov, B. V.
1984SoPh...93...95R Altcode:
A flare observed with the Hard X-Ray Imaging Spectrometer (HXIS) was
studied during its rise to maximum temperature and X-ray emission
rate. Two proximate flare loops, of lengths 2.8 × 109
cm and 1.1 × 1010 cm, rose to temperatures of 21.5 ×
106 K and 30 × 106 K, respectively, in 30
s. Assuming equal heat flux F into each loop from a thermal source
at the point where they met, we derive a simple relationship between
temperature T and loop length , which gives a loop temperture ratio
of 0.68, in close agreement with the observed ratio of 0.72. The
observations imply that heating in each loop was maintained by a thermal
flux of ∼ 5 × 109 ergs cm-2 s-1. It
is suggested that conductive heating adequately describes the rise
and maximum phase emissions in the loops and that long flare loops
reach higher temperatures than short loops during the impulsive phase
because of an equipartition of energy between them at their point
of interaction.

---------------------------------------------------------
Title: The Solar Maximum Observatory.
Authors: Rust, D. M.
1984JHATD...5..188R Altcode:
The successful retrieval and repair of the Solar Maximum Mission (SMM)
satellite by Shuttle astronauts in April 1984 permitted continuance of
solar flare observations that began in 1980. The SMM carries a soft X
ray polychromator, gamma ray, UV and hard X ray imaging spectrometers,
a coronagraph/polarimeter and particle counters. The data gathered thus
far indicated that electrical potentials of 25 MeV develop in flares
within 2 sec of onset. X ray data show that flares are composed of
compressed magnetic loops that have come too close together. Other
data have been taken on mass ejection, impacts of electron beams
and conduction fronts with the chromosphere and changes in the solar
radiant flux due to sunspots.

---------------------------------------------------------
Title: Spatial Development of X-Ray Emission during the Impulsive
Phase of a Solar Flare
Authors: de Jager, C.; Boelee, A.; Rust, D. M.
1984SoPh...92..245D Altcode:
The flare of 11 November, 1980, 17∶25 UT occurred in a magnetically
complex region. It was preceded by some ten minutes by a gradual
flare originating over the magnetic inversion line, close to a
small sunspot. This seems to have triggered the main flare (at 70
000 km distance) which originated between a large sunspot and the
inversion line. The main flare started at 17∶23∶20 UT with a slight
enhancement of hard X-rays (E &gt; 30 keV) accompanied by the formation
of a dark loop between two Hα bright ribbons. In 3-8 keV X-rays a
southward expansion started at the same time, with ν ∼- 500 km s
−1. At the same time a surge-like expansion started. It
was observable slightly later in Hα, with southward velocities
of ≳ 200 km s−1. The dark Hα loop dissolved at ∼
17∶24 UT at which time several impulsive phenomena started such as a
complex of hard X-ray bursts localized in a small area. At the end of
the impulsive phase at 17∶25∶40 UT, a coronal explosion occurred
directed southward with an initial expansion velocity of ∼ 1800 km
s−1, decreasing in 40 s to ∼500 km s−1.

---------------------------------------------------------
Title: Flare Loops Heated by Thermal Conduction
Authors: Rust, D. M.; Somov, B. V.
1984BAAS...16Q.544R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Energy-transfer processes in flares
Authors: Rust, D. M.
1984AdSpR...4g.191R Altcode: 1984AdSpR...4..191R
This paper deals with Solar Maximum Year observations that can shed
light on the roles of energetic electron beams and thermal conduction
in solar flares. The emphasis is on X-ray and UV images and on the
interpretation of chromospheric spectra. The format is that of a
one-sided debate advocating the view that most of the flare energy
that reaches the chromosphere is transferred by thermal conduction
rather than by energetic electron beams. Reference is made to papers
offering opposing points of view on this still controversial question.

---------------------------------------------------------
Title: Thermal Wave Fronts in Solar Flares
Authors: Rust, D. M.; Simnett, G. M.; Smith, D. F.
1983BAAS...15Q.919R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Solar activity.
Authors: Rust, D. M.
1983RvGSP..21..349R Altcode: 1983RvGeo..21..349R
The increased data base and scope of the theoretical models for
solar flares are reviewed. Data have been gathered from the Skylab
instrumentation, the Solar Maximum Mission, and the Very Large
Array. Skylab X ray images revealed regularly spaced bright spots on
the solar surface. Studies have also been performed on the emergence
of magnetic fields, the coronal structures defined by magnetic fields
above active regions, and the behavior and composition of post-flare
loops. It has been found that coronal transients are associated
with eruptive prominences with and without flares up to 70 pct of
the time. Two classes of solar flares have been identified, i.e.,
small volume, low altitude with a short rise time, and long decay
events with a larger coronal loop structure. Evidence for thermal and
nonthermal causes for the electron velocity distribution in the flares
is discussed. Finally, SMM data has shown chromospheric reactions to
magnetic field variations in the photosphere and the response of the
interplanetary medium to coronal transients.

---------------------------------------------------------
Title: Observations of H-alpha and microwave brightening caused by
a distant solar flare
Authors: Kundu, M. R.; Rust, D. M.; Bobrowsky, M.
1983ApJ...265.1084K Altcode:
Three subflares were observed at 6 cm λ and at Hα (6563 Å) with
the VLA and the Solar Observing Optical Network high resolution
telescopes. Synthesized maps with integration times of 10 and 30 s
show that most of the 6 cm burst emission originated in ≡10arcsec
- 15arcsec features coincident with or adjacent to Hα flare
kernels. During the onset of one of the subflares 6 cm emission was
discovered in a loop stretching &gt;105 km from the primary
flare site; this emission was associated with faint Hα flarelike
brightness at the remote footpoint of the loop. Assuming that the
energy for the distant brightening originated at the primary flare
site, it is found that ≡4 × 1024 ergs s-1
propagated along the connecting magnetic loop at a velocity of ≥
6000 km s-1. Various possible mechanisms for the distant
activation are discussed.

---------------------------------------------------------
Title: Coronal Disturbances and Their Terrestrial Effects
Authors: Rust, D. M.
1983SSRv...34...21R Altcode:
Coronal disturbances lead to geomagnetic storms, proton showers,
auroras and a wide variety of other phenomena at Earth. Yet, attempts
to link interplanetary and terrestrial phenomena to specific varieties
of coronal disturbances have achieved only limited success. Here,
several recent approaches to prediction of interplanetary consequences
of coronal disturbances are reviewed. The relationships of shocks
and energetic particles to coronal transients, of proton events to
γ-ray bursts, of proton events to microwave bursts, of geomagnetic
storms to filament eruptions and of solar wind speed increases to the
flare site magnetic field direction are explored. A new phenomenon,
transient coronal holes, is discussed. These voids in the corona appear
astride the long decay enhancements (LDE's) of 2 50 Å X-ray emission
that follow Hα filament eruptions. The transient holes are similar
to long-lived coronal holes, which are the sources of high speed solar
wind streams. There is some evidence that transient coronal holes are
associated with transient solar wind speed increases.

---------------------------------------------------------
Title: Optical Observations of Simple and Complex Flares
Authors: Rust, D. M.
1982Obs...102..118R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Solar Flares, Proton Showers, and the Space Shuttle
Authors: Rust, D. M.
1982Sci...216..939R Altcode:
The space shuttle era will focus renewed attention on the hazards of
the space environment to human habitation. The chief unpredictable
hazard for astronauts is energetic proton radiation from solar
flares. In some orbits, there is no reasonable level of shielding
material that will protect shuttle occupants from potentially lethal
doses of radiation. The effects of a solar flare that occurred during
the first flight of the Columbia are discussed and current flare
research reviewed. The emphasis is on progress made during the recent
international Solar Maximum Year toward understanding the origins of
proton showers.

---------------------------------------------------------
Title: Solar Maximum Year; Proceedings of the Symposium, Ottawa,
Canada, May 16-June 2, 1982
Authors: Svestka, Z.; Rust, D. M.; Dryer, M.
1982AdSpR...2k....S Altcode: 1982AdSpR...2.....S
Results of research conducted during the Solar Maximum Year from
August 1979 to through February 1981 are presented, focusing on flare
build-up, energy release in flares, and travelling interplanetary
phenomena. Topics examined include the relation of solar flares to the
evolution and proper motions of magnetic fields, pre-flare heating of
filaments, mass motions in a quiescent filament, multiple wavelength
observations of flaring active regions, energy transfer in solar flares,
direct evidence for chromosphere evaporation in a well-observed compact
flare, physics of the impulsive phase of solar flares, and the analysis
of ultra-fast fine structures of microwave bursts. Also considered
are the effects of electron-cyclotron masers during flares, high
energy particle acceleration in flares, particle charge interchange
during acceleration in flare regions, diamagnetic aspects of the
coronal transient phenomenon, particle acceleration by coronal and
interplanetary shock waves, and the propagation of energetic particles
in the solar wind. For individual items see A83-35202 to A83-35235

---------------------------------------------------------
Title: Study of energy release in flares
Authors: Rust, D. M.
1982AdSpR...2k...5R Altcode: 1982AdSpR...2....5R
No abstract at ADS

---------------------------------------------------------
Title: Origin and Location of the Hard X-Ray Emission in a Two-Ribbon
Flare
Authors: Hoyng, P.; Duijveman, A.; Machado, M. E.; Rust, D. M.;
Svestka, Z.; Boelee, A.; de Jager, C.; Frost, K. T.; Lafleur, H.;
Simnett, G. M.; van Beek, H. F.; Woodgate, B. E.
1981ApJ...246L.155H Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Optical and radio observations of the 1980 March 29, April 30,
and June 7 flares
Authors: Rust, D. M.; Benz, A.; Hurford, G. J.; Nelson, G.; Pick,
M.; Ruzdjak, V.
1981ApJ...244L.179R Altcode:
Ground-based solar observations are analyzed for three of the flares
discussed in the accompanying Solar Maximum Mission reports. The
principal conclusions are that H-alpha begins to brighten several
minutes before the impulsive, hard X-ray bursts, that the preflare
heating and impulsive phases of the three flares occurred in loop-shaped
structures of about 3500 km semidiameter, and that after the impulsive
phase a much larger volume (about 200 times) of flare plasma was
present for the flare main phase. Evidence is presented for the escape
of 100-500 keV electrons into the larger volume and into the corona
during the impulsive phase. For the April 30 flare, the inferred origin
of the hard X-ray burst is near the feet of the magnetic loops.

---------------------------------------------------------
Title: A Statistical Study of Solar Flares and Permanent Filament
Changes
Authors: Rust, D. M.
1981BAAS...13..820R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: VLA Observations of Large Scale Microwave Brightening Following
a Flare
Authors: Bobrowsky, M.; Kundu, M. R.; Rust, D.
1981BAAS...13..846B Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Análisis del flare en luz blanca del 7 de agosto de
1972. Espectro y estructura atmosférica
Authors: Machado, M. E.; Rust, D. M.
1981BAAA...20..147M Altcode:
Presentamos el análisis espectral de un flare en luz blanca ocurrido
el 7-8-72. Los espectros obtenidos en la región λλ 3530 a 5895
Å y la secuencia de filtrogramas centrados en 4950 y 5900 Å (200
Å de banda pasante) constituyen la más completa información sobre
un evento de esta naturaleza obtenida hasta el momento. El análisis
del espectro de Fe I y de las líneas moleculares de CN y CH muestra
que la máxima profundidad de penetración del flare es d 200 km sobre
τ5000 = 1 en la Harvard-Smithsonian Reference Atmosphere. El
análisis de las líneas de Balmer indica que el flare ocurrió en una
capa muy delgada de la atmósfera y que el calentamiento y ionización
fueron debidos a la inyección de electrones de energías superiores
a 100 keV. El análisis de la emisión continua indica que ésta es
producida por transiciones libre-ligado de hidrógeno a una temperatura
de 8500 K ± 500 K.

---------------------------------------------------------
Title: Application of X-ray imaging techniques to auroral monitoring
Authors: Rust, D. M.; Burstein, P.
1981eirs.sympT....R Altcode:
The precipitation of energetic particles into the ionosphere
produces bremsstrahlung X-rays and K-alpha line emission from
excited oxygen and nitrogen. If viewed from a spacecraft in a highly
elliptical polar orbit, this soft (0.3 - 3.0 keV) X-radiation will
provide an almost uninterrupted record of dayside and nightside
auroras. A grazing incidence X-ray telescope especially designed
for such auroral monitoring is described. High photon collection
efficiency will permit exposure times of approximately 100 seconds
during substorms. Spectrophotometry will allow users to derive the
energy spectrum of the precipitating particles. If placed in a 15
earth-radius orbit, the telescope can produce auroral X-ray images
with 30 km resolution. Absolute position of X-ray auroras can be
established with a small optical telescope co-aligned with the X-ray
telescope. Comparison of X-ray and optical images will establish the
height and global distribution of X-ray aurorae, relative to well-known
optical auroras, thus melding the new X-ray results with knowledge of
optical auroras.

---------------------------------------------------------
Title: Horizontal distribution of the X-ray energy deposit in the
chromosphere and H alpha two ribbon flares
Authors: Henoux, J. C.; Rust, D.
1980A&A....91..322H Altcode:
The two-ribbon Hα brightening and the X-ray emitting coronal loop
arcade during the very late phase of the 29 July 1973 flare are
examined. By means of a simple geometrical model of the X-ray emitting
structures, the horizontal distribution of X-radiation is computed
for several different levels in the chromosphere. It is found that an
arcade of X-ray emitting loops, commonly found over large two-ribbon
flares, gives an energy deposit pattern in the chromosphere similar
in shape to the Hα flare emission. Isophotes of the Hα brightening
are compared to the X-ray energy deposit horizontal variation profiles
from a single loop and from an arcade of loops. The brightest 29 July
isophotes fit midway between the X-ray profiles associated respectively
with a loop and an arcade. The maximum X-ray energy deposit rate of 1.5
106 ergs cm-2 s-1 is slightly higher
than the peak Hα emission rate. It is concluded that X-ray radiation
is an important source of energy for Hz flares. There seems to be no
need for in- situ energy release in the chromosphere.

---------------------------------------------------------
Title: Evidence for Electron and Proton Beams in a White-Light Flare
Authors: Rust, David M.
1980BAAS...12..910R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Spatial and temporal correlation of high and low temperature
solar flare emissions.
Authors: Rust, D. M.; Buhmann, R. W.; Dennis, B. R.; Robinson, R. D.;
Willson, R. F.; Simon, M.
1980BAAS...12..752R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Energy Release in Solar Flares
Authors: Emslie, A. G.; Rust, D. M.
1980SoPh...65..271E Altcode:
We summarize key problems in our understanding of energy release in
solar flares, as addressed by participants in a recent workshop. These
problems fall into three broad areas: (i) Transport and thermalization
of energy, (ii) acceleration of particles, and (iii) origin and
effects of mass motions. We then describe how suitably coordinated
collaborative observing sequences during the forthcoming Solar Maximum
Year are potentially capable of resolving some of these issues.

---------------------------------------------------------
Title: Application of a Magnetograph and X-Ray Telescope to the
Study of Coronal Structure Variations
Authors: Rust, D. M.
1980NASCP2098..259R Altcode: 1980sscs.nasa..259R
The application of magnetographs and X-ray imaging techniques to
determine the magnitude, structure, origin, and evolution of the
solar coronal magnetic field is examined. The spatial and temporal
resolution of the X-ray telescope is discussed and a comparison of
ground based magnetogram sequences versus a magnetograph in space is
presented. Skylab photographs of the evolution of transient coronal
holes are provided.

---------------------------------------------------------
Title: Mass ejections
Authors: Rust, D. M.; Hildner, E.; Hansen, R. T.; Dryer, M.; McClymont,
A. N.; McKenna-Lawlor, S. M. P.; McLean, D. J.; Schmahl, E. J.;
Steinolfson, R. S.; Tandberg-Hanssen, E.
1980sfsl.work..273R Altcode: 1980sofl.symp..273R
Observations and model simulations of solar mass ejection phenomena are
examined in an investigation of flare processes. Consideration is given
to Skylab and other observations of flare-associated sprays, eruptive
prominences, surges and coronal transients, and to MHD, gas dynamic and
magnetic loop models developed to account for them. Magnetic forces
are found to confine spray material, which originates in preexisting
active-region filaments, within steadily expanding loops, while surges
follow unmoving, preexisting magnetic field lines. Simulations of
effects of a sudden pressure pulse at the bottom of the corona are
found to exhibit many characteristics of coronal transients associated
with flares, and impulsive heating low in the chromosphere is found to
be able to account for surges. The importance of the magnetic field
as the ultimate source of energy which drives eruptive phenomena as
well as flares is pointed out.

---------------------------------------------------------
Title: Solar Maximum Mission not the First - OSO-7/NASA Satellite
1972AUG
Authors: Rust, D. M.
1980SciN..118..275R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Solar forecast and real-time monitoring needs of the Study
of Energy Release in Flares (SERF)
Authors: Rust, D. M.
1979stp.....2..331R Altcode:
Complementary, simultaneous observations of flares from as many
observatories, both ground based and orbiting, as possible planned
for the Solar Maximum Year are considered. The need for forecasts
of solar activity on long term, one week, and two day intervals is
described. Real time reporting is not needed, but daily summaries of
activity and permanent records are important.

---------------------------------------------------------
Title: Warming Up for the Solar Maximum Year
Authors: Rust, D. M.
1979S&T....58..315R Altcode:
The paper examines the current technology that is used in studying solar
activity and its effect on the planetary system. Attention is given
to solar flares and methods for predicting their eruptions. The Solar
Maximum Year (SMY) program that calls for intensive observations of
three aspects of solar activity, including the source of solar flare
energy, is presented. Two models that discuss whether solar flares
are thermal or nonthermal phenomena are examined.

---------------------------------------------------------
Title: Slowly moving disturbances in the X-ray corona.
Authors: Rust, D. M.; Svestka, Z.
1979SoPh...63..279R Altcode:
Sequences of soft X-ray pictures, taken aboard Skylab between May
and November, 1973, have made it possible to detect slowly moving
disturbances originating in disrupted filaments and causing subsequent
brightenings of distant coronal structures. With speeds decreasing
from ∼400 km s-1 shortly after the filament disruption to
∼10 km s-1 four or five hours later, these disturbances
appear to be identical with slow waves earlier inferred by Bruzek,
Öhman, and Yajima from chromospheric observations.

---------------------------------------------------------
Title: Energy release in solar flares. Proceedings of the workshop
on Energy Release in Flares
Authors: Rust, D. M.; Emslie, A. G.
1979cammawork.....R Altcode:
Parallel meetings of three small teams were held where theories of
thermalization, particle acceleration, and mass motion in flares were
discussed. An overview of the major scientific issues identified
for the study of energy release in flares is given. More specific
discussions of the three program areas are included. The concepts
of Joint Observing Sequences and Collaborative Observing Sequences
(COSs) developed by NASA's Solar Maximum Mission investigators are
explained. Specific observations needed for each COS are listed.

---------------------------------------------------------
Title: Physical parameters in long-decay coronal enhancements.
Authors: MacCombie, W. J.; Rust, D. M.
1979SoPh...61...69M Altcode:
X-ray images have been studied quantitatively to determine electron
temperature and density as functions of time in two long-decay X-ray
enhancements (LDE's). This is the first study of the X-ray emission from
LDE's to include all corrections for scattering and vignetting. Derived
electron density is about twice that found by Vorpahl et al. (1977) and
by Smith et al. (1977) in the same events. Our results are combined with
those for two other LDE's to find their general characteristics. The
LDE's all had the form of arcades of very bright loops which were 1-3
× 106 K hotter at the apices than along the legs. This
temperature structure was maintained for at least 8 hr in each
case. From this it is inferred that continual heating was taking place
at the loop apices. Each LDE was preceded by a filament eruption and
a white-light transient. Each was associated with a loop prominence
system (LPS) composed of cool (Te &lt; 105 K)
loops nested 2-8 × 103 km below the hot LDE loops. And,
although the energy release rates in the four events varied greatly
even 4 hr after onset, they all had similar growth rates (loop height
vs time ≅ 1 km s−1). Event lifetimes were very long,
from 24 to 72 hr. After a survey of published models, it is concluded
that only a magnetic reconnection model (e.g., Kopp and Pneuman, 1976)
is consistent with these observations of the LDE-LPS phenomenon.

---------------------------------------------------------
Title: Coronal Manifestations of Eruptive Prominences - Observations
and Interpretation.
Authors: Rust, D. M.
1979phsp.coll..252R Altcode: 1979phsp.conf..252R; 1979IAUCo..44..252R
Observations of the coronal manifestations associated with eruptive
solar prominences are discussed. Coronal brightness changes observed
to be associated with eruptive prominences include the appearance of a
thin filament in X-ray and Fe XIV coronal emissions during the period of
prominence activation, followed by the appearance of loop systems and
slowly-moving disturbances (soft-X-ray brightness changes). Dramatic
changes in the structure of the inner corona, observed in line
emissions, include loop expansions, coronal whips, coronal realignments
with prominence eruptions and transient coronal holes, all of which are
indicative of magnetic field rearrangements. Scattering observations
of outer coronal structure reveal an ejection of about 3 x 10 to
the 15 g of mass from the inner corona through the outer corona in
association with prominence eruptions. The close relationship of
prominence eruptions and coronal loop transients is discussed, and
eruptive prominences are interpreted in terms of the destabilization
of magnetic fields around the prominences.

---------------------------------------------------------
Title: Discussion
Authors: Acton, L. W.; Engvold, O.; Heasley, J. N.; Heyvaerts, J.;
Hirayama, T.; Kundu, M. R.; Leroy, J. L.; Malville, J.; Rust, D. M.;
Zirin, H.
1979phsp.coll...31A Altcode: 1979IAUCo..44...31A
No abstract at ADS

---------------------------------------------------------
Title: Discussion
Authors: Hirayama, T.; Maltby, P.; Malville, J.; Martin, S. F.; Rust,
D. M.; Spicer, D. S.
1979phsp.coll..267H Altcode: 1979IAUCo..44..267H
No abstract at ADS

---------------------------------------------------------
Title: Discussion
Authors: Anzer, U.; Raadu, M. A.; Rompolt, B.; Rust, D. M.; Sheeley,
N.; Spicer, D. S.
1979phsp.coll..171A Altcode: 1979IAUCo..44..171A
No abstract at ADS

---------------------------------------------------------
Title: Discussion
Authors: Engvold, O.; Gaizauskas, Gaizauskas; Rust, D. M.; Sheeley,
N.; Tandberg-Hanssen, E.; Ohman, Y.; Zirin, H.
1979phsp.coll..207E Altcode: 1979IAUCo..44..207E
No abstract at ADS

---------------------------------------------------------
Title: Solar flares
Authors: Rust, D. M.
1979sswp.book...51R Altcode:
The present paper deals with explosions in a magnetized solar plasma,
known as flares, whose effects are seen throughout the electromagnetic
spectrum, from gamma-rays through the visible and to the radio band. The
diverse phenomena associated with flares are discussed, along with
the physical mechanisms that have been advanced to explain them. The
impact of solar flare research on the development of plasma physics
and magnetohydrodynamics is noted. The rapid development of solar
flare research during the past 20 years, owing to the availability
of high-resolution images, detailed magnetic field measurements,
and improved spectral data, is illustrated.

---------------------------------------------------------
Title: Discussion
Authors: Acton, L. W.; Anzer, U.; Engvold, O.; Martin, S. F.; Pneuman,
G. W.; Rust, D. M.; Tandberg-Hanssen, E.; Zirin, H.
1979phsp.coll..164A Altcode: 1979IAUCo..44..164A
No abstract at ADS

---------------------------------------------------------
Title: Slowly-Moving Disturbances in the X-Ray Corona.
Authors: Rust, D. M.; Svestka, Z.
1979phsp.coll..276R Altcode: 1979IAUCo..44..276R; 1979phsp.conf..276R
A synoptic movie made from nearly 1000 pictures of the solar X-ray
corona taken by the S-054 X-ray telescope on Skylab has led to
the discovery of disturbances with propagation velocities under
100 km/sec and extending over distances of the order of one solar
radius. The disturbances are revealed as brightened coronal structures
at progressively greater distances from a central point, usually an
active region with an activated or disappearing filament. In a number of
cases these coronal brightenings were accompanied by quiescent filament
disappearances. The inferred coronal velocities and the rates of damping
were found to be in excellent agreement with the velocity curves deduced
by Bruzek (1952), in his slow wave hypothesis, and possibly confirmed
by Oehman and Oehman (1953) and Yajima (1971) to explain the activation
of filaments at great distances from flares. The fact that many of
the events showed little or no flaring associated with the filament
disappearance at onset leads to the conclusion that the source of the
slow disturbances is linked to the initial filament eruption itself,
possibly in restructuring of the magnetic fields or in the coronal
heating that typically accompanies active region filament eruptions.

---------------------------------------------------------
Title: Soft X-ray observations of large-scale coronal active region
brightenings.
Authors: Rust, D. M.; Webb, D. F.
1977SoPh...54..403R Altcode:
One-hundred fifty-six large-scale enhancements of X-ray emission
from solar active regions were studied on full-disk filterheliograms
to determine characteristic morphology and expansion rates for
heated coronal plasma. The X-ray photographs were compared with Hα
observations of flares, sudden filament disappearances, sprays and
loop prominence systems (LPS). Eighty-one percent of the X-ray events
were correlated with Hα filament activity, but only forty-four percent
were correlated with reported Hα flares. The X-ray enhancements took
the form of loops or arcades of loops ranging in length from 60 000
km to 520 000 km and averaging 15 000 km in width. Lifetimes ranged
from ≥3 hr to &gt;24 hr. Event frequency was ∼1.4 per day. X-ray
loop arcades evolved from sharp-edged clouds in cavities vacated by
rising Hα filaments. Expansion velocities of the loops were ∼50 km
s-1 immediately after excitation and 1-10 km s-1
several hours later. These long-lived loop arcades are identified with
LPS, and it is suggested that the loops outlined magnetic fields which
were reconnecting after filament eruptions. Another class of X-ray
enhanced loops stretched outside active regions and accompanied sprays
or lateral filament ejections. Hα brightenings occurred where these
loops intersected the chromosphere. Inferred excitation velocities
along the loops ranged between ∼300 and 1200 km s-1. It
is suggested that these loops outlined closed magnetic fields guiding
slow mode shocks from flares and filament eruptions.

---------------------------------------------------------
Title: Do surges heat the corona?
Authors: Rust, D. M.; Webb, D. F.; MacCombie, W.
1977SoPh...54...53R Altcode:
A comparison of X-ray filtergrams obtained during the Skylab mission
8 hr before and within 4 hr following 54 active region surges on
the disk revealed only 6 cases of long-enduring, large-scale (&gt;
10 000 km) coronal enhancements that might have been associated with
surge activity. It is concluded that there is no evidence for any
substantial increase in the temperature or amount of coronal material
during reported surges.

---------------------------------------------------------
Title: An emerging flux model for the solar phenomenon.
Authors: Heyvaerts, J.; Priest, E. R.; Rust, D. M.
1977ApJ...216..123H Altcode:
An outline is presented of the physical processes involved in the
emerging flux model, which appears to explain naturally many solar
flare observations. The separate physical phases of the basic model
include a preflare heating phase as the new flux emerges, an impulsive
phase as high-energy particles are accelerated, a flash (or explosive)
phase when the H-alpha intensity increases, and a main phase while
it decreases. The extent and morphology of the main phase emission
depend on the structure of the magnetic field region in which the new
flux finds itself imbedded. It is suggested that a (small) simple loop
flare occurs if the new flux appears in a region where no great amount
of magnetic energy in excess of potential is stored. A two-ribbon
flare occurs if the flux emerges near the polarity inversion line of
an active region that has begun to develop filaments.

---------------------------------------------------------
Title: An emerging flux model for solar flares.
Authors: Heyvaerts, J.; Priest, E.; Rust, D. M.
1977SoPh...53..255H Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Slowly Moving X-Ray Disturbances from Flares.
Authors: Rust, D. M.; Svestka, Z.
1977BAAS....9..329R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Expansion of an X-ray coronal arch into the outer corona.
Authors: Rust, D. M.; Hildner, E.
1976SoPh...48..381R Altcode:
An asymmetric, expanding arch, photographed in the inner corona with
an X-ray telescope on 13 August, 1973, is identified as the source of
the mass ejected in a white light transient in the outer corona. The
morphology, angular position, estimated mass and apparent rate of
upward acceleration of the lower coronal arch are similar to those of
the arch seen passing through the outer corona. The mass of material
removed from the lower corona is estimated at 2 × 1015 g,
and the upward movement is consistent with a constant acceleration of
12.5 m s−2 between 1.3 and 5 R⊙.

---------------------------------------------------------
Title: Coronal X-ray enhancements associated with Hα filament
disappearances
Authors: Webb, D. F.; Krieger, A. S.; Rust, D. M.
1976SoPh...48..159W Altcode:
A survey of soft X-ray images from Skylab has revealed a class of
large-scale transient X-ray enhancements in the lower corona which
are typically associated with the disappearance of Hα filaments away
from active regions. Contemporary with the Hα filament disappearance,
X-ray emitting structures appeared at or near the filament location with
shape and size resembling the filament. Eventually these structures
faded, but the filament cavity was no longer obvious. Typically
the peak of the X-ray event lagged the end of the filament
disappearance by tens of minutes. The durations of the coronal X-ray
enhancements were considerably longer than the associated Hα filament
disappearances. Major flare effects, such as chromospheric brightenings,
typically were not associated with these X-ray events.

---------------------------------------------------------
Title: Observations of Flare-Associated Magnetic Field Changes
Authors: Rust, D. M.
1976RSPTA.281..427R Altcode: 1976RSLPT.281..427R
Although it is widely accepted that energy for solar flares must
be sought in rapid conversion of magnetic energy, observations of
flare-associated magnetic field changes have proven difficult
and controversial. Different observers have come to widely
varying conclusions about the nature and reality of the reported
flare-associated field changes. However, it is possible to reconcile
these differences because most of the observations have been made at a
level of precision comparable with the maximum field changes that even
the largest flares could result from. High resolution filtergrams and
magnetograms made within the past five years have made it possible to
deduce that flares are associated with the emergence of new flux and
with its reconnexion to older fields. Recent observations are reviewed.

---------------------------------------------------------
Title: Optical and Magnetic Measurements of the Photosphere and
Low Chromosphere
Authors: Rust, D. M.
1976RSPTA.281..353R Altcode: 1976RSLPT.281..353R
Sequences of photographs at a resolution of 1' ' achieved
during the past ten years have had a very significant impact upon our
understanding of the development, mature structure and decay of active
regions. Cinematic studies, especially, have allowed the emergence of
new fields and their motions within the active centre to be studied in
detail. Cinematic magnetic observations show how sunspots decay through
the outward flight of tiny knots of magnetic flux. The newest advances
are being made with arrays of photosensitive diodes at the focal planes
of high dispersion spectrographs. The diode array at the Sacramento
Peak Observatory produces simultaneous photometric observations at
many different wavelengths throughout the visible and near infrared
spectrum. Quantitative studies of magnetic fields and chromospheric
structure are discussed. In particular, the moving magnetic features
apparently produce surges in the superpenumbra around large sunspots.

---------------------------------------------------------
Title: Expansion of an X-ray Coronal Arch Into the Outer Corona
Authors: Rust, D. M.; Hildner, E.
1976BAAS....8..368R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Enhancement of Soft X-ray Emission Associated with the Motion
of Cool Material Through the Lower Corona
Authors: Rust, D. M.; Webb, D. F.
1976BAAS....8..316R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: An active role for magnetic fields in solar flares.
Authors: Rust, D. M.
1976SoPh...47...21R Altcode:
Magnetic fields in the low corona are the only plausible source of
energy for solar flares. Other energy sources appear inadequate
or uncorrelated with flares. Low coronal magnetic fields cannot
be measured accurately, so most attention has been directed toward
measurements of the photospheric magnetic fields from which coronal
developments may be inferred. Observations of these magnetic fields
are reviewed. It is concluded that, except possibly for the largest
flares, changes in the photospheric magnetic fields in flaring centers
are confined to evolutionary changes associated with emergence of new
magnetic flux. Flare observations with the 10830 Å line of helium,
in particular, are discussed. It is concluded that the brightest
flare knots appear near points of emergent magnetic flux. Pre-flare
activation and eruptions of Hα filaments are discussed. It is
concluded that the rapid motions in filaments indicate unambiguously
that the magnetic fields in the low corona are severely disrupted
prior to most flares. The coronal signature of Hα filament eruptions
is illustrated with soft X-ray photographs from the S-054 experiment
of the NASA Skylab mission. An attempt is made, by studying X-ray
flare morphology, to determine whether flares grow by reconnections
between adjacent or intertwined magnetic elements or by triggering, in
which each flaring loop drives adjacent loops to unstable states. It is
concluded that successive loop brightenings are most easily interpreted
as the result of magnetic field reconnections, although better time
resolution is required to settle the question. A model of magnetic
field reconnections for flares associated with filament activation
and emerging magnetic flux is presented.

---------------------------------------------------------
Title: Magnetic fields in solar active regions.
Authors: Rust, D. M.
1976npsa.conf...19R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Magnetic Fields in Solar Active Regions
Authors: Rust, D. M.
1976saop.book...33R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Energy Balance in a Magnetically Confined Coronal Structure
Observed by OSO-7
Authors: Neupert, W. M.; Nakagawa, Y.; Rust, D. M.
1975SoPh...43..359N Altcode:
A model of a coronal region of enhanced Fexv and FeXVI emission is
developed and its energy balance is examined using extreme ultraviolet
observations from OSO-7 together with calculations of possible
force-free coronal magnetic field configurations. The coronal emissions
overlying the photospheric boundary between regions of opposite magnetic
polarity are found to be associated with generally non-potential
(current-carrying) magnetic fields in the forms of arches with
footpoints in regions of opposite polarity. The orientation of these
arches relative to the neutral line changes with degree of ionization
of the emitting ion (which we infer from our limb observations to
be a function of height) and may be evidence of differing electric
currents along various field lines. The appearance of a coronal arch,
seen side-on, can conveniently be represented by a parabola and a
detailed analysis (Appendix) shows this to be a realistic approximation
that should be generally useful in analyzing two-dimensional pictures
of coronal structures. Applying this analysis to the most prominent
coronal region observed in the radiations of Fexv and Fexvi, we
find a maximum in the electron temperature, Te, of 2.6 ×
106K at the top of arches whose heights are 20000-40000
km and whose footpoints are separated by ≈ 100000 km. A temperature
gradient of ▽Te≈5 × 10-5K cm-1
is found in this coronal structure. Radiative losses are typically
fifteen times greater than conductive losses and the energy deposition
required to maintain the coronal feature is nearly uniformly distributed
along its length.

---------------------------------------------------------
Title: A model for the solar flare
Authors: Canfield, R. C.; Priest, E. R.; Rust, D. M.
1975STIN...7615007C Altcode:
It is suggested that many solar flares occur due to an interaction
between newly emerging magnetic flux and an active region filament. A
current sheet forms between the new and old flux and, when its
electric current density exceeds a critical value, rapid magnetic
fields reconnection takes place. Electrons are then accelerated
to high energies and follow the magnetic field lines down to the
chromosphere where they produce several (typically three) bright H
alpha knots. Magnetic energy is continuously released as reconnected
prominence fields are allowed to untwist. Two ribbons of H alpha
emission are produced by one or more of three mechanisms: energetic
particles, thermal conduction or shocks due to infalling material.

---------------------------------------------------------
Title: The work of the diode array: He 10 830 observations of spicules
and subflares
Authors: Rust, D. M.; Bridges, C. A., III
1975SoPh...43..129R Altcode:
At a spatial resolution of 1″ and with spectral passbands of 0.25-0.47
Å, the chromospheric fine structure was studied with an array of 512
silicon photodiodes. The high quantum efficiency of the diodes in the
near infrared allowed low noise spectroheliograms to be constructed
from observations in the lines of H I, Ca II, and He I. Magnetograms of
the underlying photosphere were obtained simultaneously. Tachograms in
the He 10830 Å line revealed 1″ points and elongated features that
are interpreted as spicules seen against the disk. Active regions
and filaments at 10830 are compared with Hα and Ca II (8542 Å)
features. Filament contrast increases with the proximity of bright
plage. Twelve subflares were studied and in eight cases, 3-5″
kernels of He I emission appeared over small, growing pores or over
5″ patches of magnetic field emerging through the photosphere. All
the subflares showed 10830 emission, contrary to established belief
that the 10830 line goes into emission only in the largest flares. All
the subflares included at least one emission kernel over regions where
the photospheric magnetic field, as seen with a resolution of 1-2″,
broke down into a mosaic of both polarities with 3-5″ diam. elements.

---------------------------------------------------------
Title: Coronal X-ray Transient Events Associated with Hα Filament
Disappearances
Authors: Webb, D.; Krieger, A.; Rust, D.; Vaiana, G.
1975BAAS....7..430W Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Moving Coronal Clouds Observed with the Skylab S-054 X-ray
Telescope.
Authors: Rust, D. M.; Webb, D. T.
1975BAAS....7Q.431R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: EUV Emission, Filament Activation and Magnetic Fields in a
Slow-Rise Flare
Authors: Rust, D. M.; Nakagawa, Y.; Neupert, W. M.
1975SoPh...41..397R Altcode:
The evolution of coronal and chromospheric structures is examined
together with magnetograms for the 1B flare of January 19, 1972. Soft
X-ray and EUV studies are based on the OSO-7 data. The Hα filtergrams
and magnetograms came from the Sacramento Peak Observatory. Theoretical
force-free magnetic field configurations are compared with structures
seen in the soft X-ray, EUV and Hα images. Until the flare,
two prominent spots were connected by a continuous dark filament
and their overlying coronal structure underwent an expansion at the
sunspot separation rate of 0.1 km s−1. On January 19, the
flare occurred as new magnetic fields emerged at ∼ 1019
Mx h−1 beneath the filament, which untwisted and erupted
as the flare began. The pre-flare coronal emissions remained unchanged
during the flare except for the temporary addition of a localized
enhancement that started 5 min after flare onset. EUV lines normally
emitted in the upper transition region displayed a sudden enhancement
coinciding in time and location with a bright Hα point, which is
believed to be near the flare `trigger' or onset point. The EUV flash
and the initial Hα brightening, both of which occurred near the center
of the activated filament, were followed by a second EUV enhancement
at the end of the filament. The complete disruption of the filament
was accompanied by a third EUV enhancement and a rapid rise in the soft
X-ray emission spatially coincident with the disappearing filament. From
the change of magnetic field inferred from Hα filtergrams and from
force-free field calculations, the energy available for the flare is
estimated at approximately 1031 erg. Apparently, changes
in the overlying coronal magnetic field were not required to provide
the flare energy. Rather, it is suggested that the flare actually
started in the twisted filament where it was compressed by emerging
fields. Clearly, the flare started below the corona, and it appears that
it derived its energy from the magnetic fields in or near the filament.

---------------------------------------------------------
Title: The Work of the Diode Array
Authors: Rust, D. M.; Bridges, C. A.
1975BAAS....7..365R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Inference of the Hard X-Ray Source Dimensions in the 1972,
August 7, White Light Flare
Authors: Rust, D. M.
1975IAUS...68..243R Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Analysis of the August 7, 1972 White Light Flare: Light Curves
and Correlation with Hard X-Rays
Authors: Rust, D. M.; Hegwer, F.
1975SoPh...40..141R Altcode:
Cinematic, photometric observations of the 3B flare of August 7, 1972
are described in detail. The time resolution was 2 s; the spatial
resolution was 1-2″. Flare continuum emissivity at 4950 Å and at
5900 Å correlated closely in time with the 60-100 keV non-thermal X-ray
burst intensity. The observed peak emissivity was 1.5 × 1010
erg cm−2 s−1 and the total flare energy in the
3900-6900 Å range was ∼1030 erg. From the close temporal
correspondence and from the small distance (3″) separating the layers
where the visible emission and the X-rays arose, it is argued that the
hard X-ray source must have had the same silhouette as the white light
flare and that the emission patches had cross-sections of 3-5″. There
was also a correlation between the location of the most intense visible
emissions near sunspots and the intensity and polarization of the 9.4
GHz radio emission. The flare appeared to show at least three distinct
particle acceleration phases: one, occurring at a stationary source
and associated with proton acceleration gave a very bluish continuum
and reached peak intensity at ∼ 1522 UT. At 1523 UT, a faint wave
spread out at 40 km s−1 from flare center. The spectrum
of the wave was nearly flat in the range 4950-5900 Å. Association
of the wave with a slow drift of the microwave emission peak to lower
frequencies and with a softening of the X-ray spectrum is interpreted
to mean that the particle acceleration process weakened while the region
of acceleration expanded. The observations are interpreted with the aid
of the flare models of Brown to mean that the same beam of non-thermal
electrons that was responsible for the hard X-ray bremsstrahlung also
caused the heating of the lower chromosphere that produced the white
light flare.

---------------------------------------------------------
Title: Analysis of the August 7, 1972 White Light Flare: Its Spectrum
and Vertical Structure
Authors: Machado, M. E.; Rust, D. M.
1974SoPh...38..499M Altcode:
Spectral data on a white light wave occurring during the explosive
phase of the August 7 flare were obtained simultaneously with three
telescopes at the Sacramento Peak Observatory. Spectrograms in
the region λλ3530 to 5895 and sequences of filtergrams (∼ 200
Å halfwidth) at 4950 Å and 5900 Å constitute the most complete
record of white light flare emission obtained to date. Analysis of
the iron line spectrum and of the CN and CH molecular lines shows
that the maximum depth of the emission in the flare wave is about
200 km above the photosphere of the Harvard-Smithsonian Reference
Atmosphere. Analysis of the Balmer lines gives an electron density of
3 × 1013 cm−3 where the continuum emission
is present. From the Balmer line analysis, it is concluded that, in
agreement with Canfield (1974) and Shmeleva and Syrovatskii (1973),
the flare occurs in a thin layer and that the heating and ionization of
the flaring layers are due to the injection of 100 keV electrons. There
is no need to postulate filamentary structure in the flaring layer in
order to explain the observations. Analysis of the continuum emission
in the wave indicates that it is produced by free-bound transitions
of hydrogen at a temperature of ∼ 8500 K. In the impulsive phase
of the flare emission arose from short-lived bluish knots which could
not be studied in detail. In the following phase, the one to which the
conclusions in this paper refer, the continuum emission coincided with
the Hα ribbon expansion (the explosive phase). We identify it with the
`yellowish-white' flares reported by Trouvelot (1891) and others.

---------------------------------------------------------
Title: The late June 1972 CINOF flares
Authors: Rust, D. M.; Roy, J. R.
1974erp..rept.....R Altcode:
This report is the result of an analysis of observations obtained during
the campaign for integrated observations of solar flares. The aim
was to obtain a more complete set of optical, radio, X-ray, EUV, and
particle observations of a normal solar flare than has been available
from earlier, uncoordinated efforts. Flares observed in the McMath
regions are discussed, with emphasis on optical and X-ray observations.

---------------------------------------------------------
Title: Gyro-Resonance Emission Transverse to the Magnetic Field of
a Large Spot Group
Authors: Graf, Werner; Rust, David M.
1974BAAS....6S.287G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: The Spectrum and Vertical Structure of the August 7, 1972
White Light Flare
Authors: Machado, Marcos E.; Rust, David M.
1974BAAS....6Q.291M Altcode:
No abstract at ADS

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Title: Preliminary Interpretation of Diode Array Simultaneous
Observations of He I and Ca II Line Profiles in Collaboration with ATM
Authors: Linsky, J. L.; Dunn, R. B.; Rust, D. M.
1974BAAS....6S.290L Altcode:
No abstract at ADS

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Title: A 512-channel photodiode array for solar observations.
Authors: Dunn, R. B.; Rust, D. M.; Spence, G. E.
1974inas.conf..109D Altcode:
No abstract at ADS

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Title: A 512-channel photodiode array for solar observations
Authors: Dunn, R. B.; Rust, D. M.; Spence, G. E.
1974SPIE...44..109D Altcode:
The Sacramento Peak Observatory has developed and placed in operation
an array of photodiodes in the focal plane of a high dispersion
spectrograph. The diodes record solar phenomena in the 4000-11000 A
range. Signals from the diodes are digitized and computer processed into
photographs or other output forms in real time. By varying the placement
of 32-diode blocks in the spectrograph, any combination of wavelengths
may be used in the construction of spectrograms, spectroheliograms,
magnetograms and tachograms. Spatial resolutions vary between 1/2 and 2
arcsec with a spectral resolution of up to 0.02 A. The signal-to-noise
ratio for a single observation is limited in most cases by scintillation
to 300:1. Several examples of computer processed photograms are given.

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Title: Magnetic fields, loop prominences and the great flares of
August, 1972
Authors: Rust, David M.; Bar, Varda
1973SoPh...33..445R Altcode:
Lines of magnetic force, computed under the assumption that the solar
corona is free of electric currents, have been compared with loop
prominence systems associated with three flares in August, 1972. The
computed fields closely match the observations of loops at a height of
40000 km at times 3-4 h after onset of the associated flares. Inferred
magnetic field intensities in the loops range from 1300 G where
the loops converge into a sunspot to 50-80 G at 40 000 km above the
photosphere. The first-seen and lowest-lying loops are sheared with
respect to the calculated fields. Higher loops conform more closely
to the current-free fieldlines. A model of Barnes and Sturrock is used
to relate the degree of shear to the excess magnetic energy available
during the flare of August 7. On various lines of evidence, it is
suggested that magnetic energy was available to accelerate particles
not only during the impulsive phase of the flare, but also during the
following 2-3 h. The particle acceleration region seems to be in the
magnetic fields just above the visible loops. The bright outer edges of
the flare ribbons are identified as particle impact regions. The dense
knots of loop prominence material fall to the ribbons' inner edges.

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Title: Analysis of the August 7, 1972 White Light Flare: Changes in
the Magnetic and Velocity Fields
Authors: Rust, David M.
1973SoPh...33..205R Altcode:
Measurements with the Doppler-Zeeman Analyzer reveal red shifts and
decreasing magnetic fields in the photosphere immediately below the
center of the August 7, 1972 proton flare. These observations are
combined with spectra and photographs of sunspot developments in the
region to produce a consistent picture of fluctuations in orientation
and strength in the fields of three spots intimately connected with
the flare. Before the flare, the photosphere appears to experience an
upheaval of material frozen into rising lines of magnetic force. After
the start of the flare and through the following 4 h, the motion
is downward.

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Title: Magnetic Fields of the Loop Prominences of August 2, 7,
and 11, 1972
Authors: Bar, Varda; Rust, David M.
1973BAAS....5Q.269B Altcode:
No abstract at ADS

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Title: Solar High-Resolution Radio Measurements of Active Regions
at a Wavelength of 2.8 cm.
Authors: Grebenkemper, C. J.; Rust, D. M.
1973BAAS....5R..21G Altcode:
No abstract at ADS

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Title: The Great Solar Flares of August, 1972
Authors: Rust, David M.
1972S&T....44..226R Altcode:
No abstract at ADS

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Title: Flares and Changing Magnetic Fields
Authors: Rust, David M.
1972SoPh...25..141R Altcode:
An observational study of maps of the longitudinal component of the
photospheric fields in flaring active regions leads to the following
conclusions: The broad-wing Hα kernels characteristic of the impulsive
phase of flares occur within 10″ of neutral lines encircling features
of isolated magnetic polarity (`satellite sunspots').

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Title: Real-time Analysis of Flare-associated Photospheric Magnetic
Fields
Authors: Rust, David M.
1972BAAS....4..390R Altcode:
No abstract at ADS

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Title: Magnetic Fields in Solar Active Regions
Authors: Rust, David M.
1972PrAA...30...33R Altcode:
No abstract at ADS

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Title: Coronal Magnetic Fields above Active Regions
Authors: Rust, D. M.; Roy, J. -R.
1971IAUS...43..569R Altcode:
No abstract at ADS

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Title: Vertical Velocities and Horizontal Wave Propagation in the
Solar Photosphere
Authors: Musman, Steven; Rust, David M.
1970SoPh...13..261M Altcode:
We used the Sacramento Peak Doppler-Zeeman Analyzer to study the
velocity and magnetic fields in 60″ × 300″ areas on the solar
disk. We map the steady component of the line-of-sight velocity
and longitudinal magnetic fields and compare them with the coarse
Ca+ network. The collective phase behavior of the 5-min
oscillations is studied in detail. We find large scale phase coherence,
including waves with typical horizontal phase velocities of 100 km/sec
which can be followed up to 50 000 km. The important oscillatory
features are interpreted in terms of the properties of modified
sound waves. We find no apparent relationship between the steady and
oscillatory fields.

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Title: Magnetic Fields in Quiescent Solar
Prominences. II. Photospheric Sources
Authors: Rust, David M.
1970ApJ...160..315R Altcode:
Magnetograph observations of the photospheric magnetic fields 100000
km on either side of quiescent filaments have been made by using the
5250 A line of iron. Resolution was 5". The region ("neutral band")
below stable filaments is free of radial fields more intense than 5
gauss. Filament structure is extremely sensitive to fields near the
neutral hand. Filaments detour around local field concentrations or
thin down enough to squeeze by. Occasionally, a filament will break
up and reform about 30" away from intruding fields. Comparisons of the
magnetic flux through filaments with that measured on either side of the
neutral band show that the magnetograph underestimates the flux outside
active regions by a factor of 4. A comparison of observations with
the Kippenhahn and Schltiter magnetohydrostatic model of prominences
tends to confirm the correctness of the model. Sections of observed
filaments are unstable and appear to be subject to disappearance when
a nascent bipolar feature appears in the neutral band.

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Title: Comparisons of Photospheric Magnetograms and Hα Filtergrams
Authors: Rust, David M.; Smith, Sara F.
1969BAAS....1..292R Altcode:
No abstract at ADS

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Title: Two-Dimensional Observations of Solar Oscilating Regions
Authors: Musman, Steven A.; Rust, David M.
1969BAAS....1S.287M Altcode:
No abstract at ADS

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Title: Chromospheric Explosions and Satellite Sunspots
Authors: Rust, David M.
1968IAUS...35...77R Altcode:
No abstract at ADS

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Title: Magnetic Field Changes during Solar Flares.
Authors: Rust, David M.
1968AJS....73S..75R Altcode:
Longitudinal magnetic field intensities have been measured during
flares in several solar active regions. The observations were made
with the Mt. Wilson magnetograph operating on the Fe line at 5250
A. Spacial resolution was 10 sec of arc, and time resolution was
5 to 10 min. Observations of several subflares and Class 1 flares
show that magnetic energy losses are comparable with estimated flare
energies of about 1030 ergs. The magnetic energy in an active region
increases in the half-hour preceeding the flare, and in a similar time
just afterward it again increases to roughly the pre-flare value. The
conclusion drawn is that flares start in an instable magnetic field
configuration which forms as new sunspots rise to the photo- sphere
or as established spots change. Observations are presented which show
that flares begin near magnetic features that have the polarity opposite
to that of the surrounding magnetic fields. These "satellite sunspots"
are not always visible in integrated light. The fields of these features
weaken simultaneously with flares and with explosive surges.

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Title: Magnetic Fields in Quiescent Solar Prominences. I. Observations
Authors: Rust, David M.
1967ApJ...150..313R Altcode:
A new magnetograph, operated on the Ha emission line, has been used
to measure the line-of-sight field intensity in nearly 100 quiescent
prominences The magnetic sensitivity is 2 gauss The measurement
technique is described. The observed prominences were divided into
three classes roughly according to their position with respect
to active regions. High-latitude ("polar crown") prominences most
distant from the current sunspot zone usually showed fields of about 5
gauss. More recently formed prominences near the high-latitude border
of fading bipolar magnetic regions also showed 5 gauss fields. The
third class, sunspot zone prominences, showed fields up to 60 gauss;
however, the median field was only about 8 gauss. The observations
of field intensity and polarity indicate that these are determined
by the nearby and underlying photospheric fields. The characteristic
size of the over-all field structures supporting prominences must
be about 50000-100000 km. The pattern of polarities observed in
the aged polar crown shows that there is no detectable large scale
(Ro) distortion of the lines of force in the solar atmosphere by
the differential rotation. Observations at 20" resolution reveal
that the horizontal field intensity usually increases with height
above the limb. This observed height gradient, aH/az 10- gauss/km,
is necessary and sufficient to demonstrate the support of prominences
by Lorentz forces. The observations tend to confirm the validity of
the theoretical prominence model of Kippenhahn and SchlUter.

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Title: Measurements of the Magnetic Fields in Quiescent Solar
Prominences.
Authors: Rust, David Maurice
1966PhDT.........7R Altcode:
No abstract at ADS

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Title: The solar magnetograph of the High Altitude Observatory
Authors: Lee, R. H.; Rust, D. M.; Zirin, H.
1965ApOpt...4.1081L Altcode:
Available from <A
href="http://www.opticsInfoBase.org/abstract.cfm?id=13895;">http://www.opticsInfoBase.org/abstract.cfm?id=13895;</A>