Author name code: shine
ADS astronomy entries on 2022-09-14
author:"Shine, Richard A."
------------------------------------------------------------------------
Title: The Hinode Spectro-Polarimeter
Authors: Lites, B. W.; Akin, D. L.; Card, G.; Cruz, T.; Duncan, D. W.;
Edwards, C. G.; Elmore, D. F.; Hoffmann, C.; Katsukawa, Y.; Katz, N.;
Kubo, M.; Ichimoto, K.; Shimizu, T.; Shine, R. A.; Streander, K. V.;
Suematsu, A.; Tarbell, T. D.; Title, A. M.; Tsuneta, S.
Bibcode: 2013SoPh..283..579L
Altcode:
The joint Japan/US/UK Hinode mission includes the first large-aperture
visible-light solar telescope flown in space. One component of the
Focal Plane Package of that telescope is a precision spectro-polarimeter
designed to measure full Stokes spectra with the intent of using those
spectra to infer the magnetic-field vector at high precision in the
solar photosphere. This article describes the characteristics of the
flight hardware of the HinodeSpectro-Polarimeter, and summarizes its
in-flight performance.
Title: Interaction of Cometary Material With the Solar Corona:
EUV Observations and MHD Simulations
Authors: Liu, W.; Jia, Y.; Downs, C.; Schrijver, C.; Saint-Hilaire,
P.; Battams, K.; Tarbell, T. D.; Shine, R. A.
Bibcode: 2012AGUFMSH13B2254L
Altcode:
Extreme ultraviolet (EUV) emission from two recent sun-grazing comets,
C/2011 N3 and C/2011 W3 (Lovejoy), has been observed in the solar corona
for the first time by the SDO/AIA and STEREO/EUVI instruments (Schrijver
et al. 2011). These observations provided a unique opportunity to
investigate the interaction of the cometary material with the solar
corona and probe their physical conditions. We present here EUV
observations and MHD simulations on this subject, focusing on the
deceleration of the cometary tail material within the corona. We found
that despite their different local coronal environments, the two comets
exhibited quite similar characteristics. The initial EUV emitting tail
had a projected velocity of 100-200 km/s, which was much lower than the
orbital velocity of 500-600 km/s in the plane-of-sky. This indicates
that significant deceleration had taken place while the tail material
was heated to coronal temperatures on the order of 1 MK before it
started to emit in EUV (Bryans & Pesnell 2012). After its initial
appearance, the tail further experienced a projected deceleration
of ~1 km/s^2 (or 4 g_Sun). In particular, in the Lovejoy case, the
tail appeared as clusters of bright parallel striations roughly at
right angles to the orbit direction, suggestive of magnetic field
lines illuminated by the plasma frozen onto them. These striations
came to a stop and then accelerated in an opposite direction (seen
in projection), approaching a constant velocity of ~50 km/s. These
observations suggest that a Lorentz force from the coronal magnetic
field was operating on the newly ionized cometary plasma. To test this
hypothesis and understand tail deceleration mechanisms, we adopted a
multi-fluid MHD model (Jia et al. 2012) to simulate the interaction
between charged particles and the magnetized coronal plasma. We used
potential extrapolation (Schrijver & DeRosa 2003) and a more
sophisticated global MHD model (Lionello et al. 2009) to infer the
magnetic field and plasma conditions of the corona along the comet's
orbit as inputs to the simulations. We will compare the observations and
simulation results, and discuss the implications for using sun-grazing
comets as probes to the solar corona in the context of NASA's future
Solar Probe Plus mission.
Title: Signatures of Moving Magnetic Features in and above the
Photosphere
Authors: Hagenaar, H.; Shine, R.; Ryutova, M.; Dalda, A. S.
Bibcode: 2012ASPC..454..181H
Altcode:
Hinode/SOT observations of NOAA AR 10933 from 2007 Jan 4 16:14 UT -
Jan 6 22:20 UT are used to study MMFs (moving magnetic features) in the
periphery of the region's large sunspot and the surrounding moat. The
data consist of a nearly continuous set of Fe 6302 Å Stokes V images
with sets of G band and Ca II H filtergrams at various cadences, FOV's,
and resolutions plus some SpectroPolarimeter (SP) scans. We also used
TRACE images in 171 Å to follow any possible signatures at higher
temperatures. We applied automatic object recognition and tracking
to the MMFs as seen in the Fe 6302 Å Stokes V images. An SP scan
was used to determine the line profiles for several paths. Reliable
inversions have not yet been done, but we find a few locations of
possible supersonic downflows from the Stokes IQUV line profiles. The
population of MMFs on the East side of the sunspot is much higher
than on the opposite side, mostly involving a large number of mixed
polarity MMFs. Consequently, the chromosphere shows strongly enhanced
brightenings with a clear pattern: enhanced brightenings in Ca H
outline the locations where opposite polarity MMFs meet. This activity
does not prevent formation of active low lying “closed” loops at
coronal temperatures seen in the TRACE 171 Å line. The other side,
with fewer MMFs, shows a pattern that we found earlier: regions with
an MMF deficiency show long living “open” coronal loops. This work
was supported by NASA contract NNM07AA01C.
Title: Some Like it Hot: the Trajectory of Sungrazing Comet C/2011 W3
(Lovejoy) in the Solar Neighborhood.
Authors: Saint-Hilaire, Pascal; Chodas, P. W.; Battams, K.; Tarbell,
T. D.; Shine, R. A.; Liu, W.; Thompson, W. T.; Comet Lovejoy
Collaboration Team
Bibcode: 2012AAS...22052107S
Altcode:
Sungrazing comet Lovejoy (C/2011 W3) was a recent spectacle in the sky,
observed from the ground and by a host of space-based instruments,
including several solar observatories. It is the first sungrazing comet
in recent memory to have survived perihelion (q 1.2 Rs). It is only
the second sungrazer to have been observed in the Sun's low corona in
the extreme ultra-violet (EUV), where a plethora of EUV observations
were obtained by the SDO and STEREO spacecraft. Such an occurrence
can be used to probe the solar corona and test our understanding
of plasma and cometary physics. In this work, we use the best orbit
elements currently available to plot the path of the comet's nucleus on
solar EUV images from SDO/AIA, both STEREO/EUVIs, and yellow continuum
(near the Na D lines) images from Hinode/SOT. We compare the predicted
positions and timing of the comet's nucleus to the latter, while the
SDO and STEREO EUV observations are used to estimate the distance at
which the EUV tail appears behind the comet's nucleus.
Title: Wavelength Dependence of the Helioseismic and Magnetic Imager
(HMI) Instrument onboard the Solar Dynamics Observatory (SDO)
Authors: Couvidat, Sébastien; Schou, Jesper; Shine, Richard A.;
Bush, Rock I.; Miles, John W.; Scherrer, Philip H.; Rairden, Richard L.
Bibcode: 2012SoPh..275..285C
Altcode: 2011SoPh..tmp..150C; 2011SoPh..tmp..219C; 2011SoPh..tmp...33C;
2011SoPh..tmp..110C
The Helioseismic and Magnetic Imager (HMI) instrument will produce
Doppler-velocity and vector-magnetic-field maps of the solar surface,
whose accuracy is dependent on a thorough knowledge of the transmission
profiles of the components of the HMI optical-filter system. Here we
present a series of wavelength-dependence calibration tests, performed
on the instrument from 2005 onwards, to obtain these profiles. We
obtained the transmittances as a function of wavelength for the tunable
and non-tunable filter elements, as well as the variation of these
transmittances with temperature and the angle of incidence of rays of
light. We also established the presence of fringe patterns produced by
interferences inside the blocking filter and the front window, as well
as a change in transmitted intensity with the tuning position. This
thorough characterization of the HMI-filter system confirmed the very
high quality of the instrument, and showed that its properties are
well within the required specifications to produce superior data with
high spatial and temporal resolution.
Title: Initial Calibration of the Atmospheric Imaging Assembly (AIA)
on the Solar Dynamics Observatory (SDO)
Authors: Boerner, Paul; Edwards, Christopher; Lemen, James; Rausch,
Adam; Schrijver, Carolus; Shine, Richard; Shing, Lawrence; Stern,
Robert; Tarbell, Theodore; Title, Alan; Wolfson, C. Jacob; Soufli,
Regina; Spiller, Eberhard; Gullikson, Eric; McKenzie, David; Windt,
David; Golub, Leon; Podgorski, William; Testa, Paola; Weber, Mark
Bibcode: 2012SoPh..275...41B
Altcode:
The Atmospheric Imaging Assembly (AIA) instrument onboard the Solar
Dynamics Observatory (SDO) is an array of four normal-incidence
reflecting telescopes that image the Sun in ten EUV and UV wavelength
channels. We present the initial photometric calibration of AIA,
based on preflight measurements of the response of the telescope
components. The estimated accuracy is of order 25%, which is consistent
with the results of comparisons with full-disk irradiance measurements
and spectral models. We also describe the characterization of the
instrument performance, including image resolution, alignment,
camera-system gain, flat-fielding, and data compression.
Title: Design and Ground Calibration of the Helioseismic and Magnetic
Imager (HMI) Instrument on the Solar Dynamics Observatory (SDO)
Authors: Schou, J.; Scherrer, P. H.; Bush, R. I.; Wachter, R.;
Couvidat, S.; Rabello-Soares, M. C.; Bogart, R. S.; Hoeksema, J. T.;
Liu, Y.; Duvall, T. L.; Akin, D. J.; Allard, B. A.; Miles, J. W.;
Rairden, R.; Shine, R. A.; Tarbell, T. D.; Title, A. M.; Wolfson,
C. J.; Elmore, D. F.; Norton, A. A.; Tomczyk, S.
Bibcode: 2012SoPh..275..229S
Altcode:
The Helioseismic and Magnetic Imager (HMI) investigation (Solar
Phys. doi:10.1007/s11207-011-9834-2, 2011) will study the solar
interior using helioseismic techniques as well as the magnetic field
near the solar surface. The HMI instrument is part of the Solar
Dynamics Observatory (SDO) that was launched on 11 February 2010. The
instrument is designed to measure the Doppler shift, intensity, and
vector magnetic field at the solar photosphere using the 6173 Å Fe I
absorption line. The instrument consists of a front-window filter, a
telescope, a set of waveplates for polarimetry, an image-stabilization
system, a blocking filter, a five-stage Lyot filter with one tunable
element, two wide-field tunable Michelson interferometers, a pair
of 40962 pixel cameras with independent shutters, and
associated electronics. Each camera takes a full-disk image roughly
every 3.75 seconds giving an overall cadence of 45 seconds for the
Doppler, intensity, and line-of-sight magnetic-field measurements
and a slower cadence for the full vector magnetic field. This article
describes the design of the HMI instrument and provides an overview of
the pre-launch calibration efforts. Overviews of the investigation,
details of the calibrations, data handling, and the science analysis
are provided in accompanying articles.
Title: Monitoring Image Alignments and Flat Fields for AIA/SDO
Data Images
Authors: Shine, Richard A.; Wolfson, C.; Boerner, P. F.; Tarbell,
T. D.; Nightingale, R. W.
Bibcode: 2011SPD....42.2126S
Altcode: 2011BAAS..43S.2126S
The images from the 4 telescopes on the Atmospheric Imaging Assembly
(AIA) on board the NASA Solar Dynamics Observatory (SDO) have different
offsets (from sun center), plate scales, and absolute rotations that
can be measured and corrected for accurate alignment. The most variable
of these is the offsets presumably due to small thermal flexings of
the telescopes. Here we describe the techniques used to make these
measurements and show how the image alignments vary with time. Weekly
measurements are made as part of the data monitoring that capture much
of the drift in the geometric corrections but shorter time variations
of typically a pixel also exist in the offsets. Angles and scales
have much better short term stability. We hope to eventually capture
these variations for the mission or at least provide software for
end users.
We also describe progress made in determining flat
fields for the 10 wavebands and show how these have been varying over
the mission to date. This work was supported by NASA under the
SDO/AIA contract NNG04EA00C.
Title: Temporal Relation Between the Disappearance of Penumbral
Fine-scale Structure and Evershed Flow
Authors: Kubo, M.; Ichimoto, K.; Lites, B. W.; Shine, R. A.
Bibcode: 2011ApJ...731...84K
Altcode: 2011arXiv1102.1137K
We investigate the temporal relation between the Evershed flow,
dot-like bright features (penumbral grain), the complex magnetic
field structure, and dark lanes (dark core) along bright filaments in
a sunspot penumbra. We use a time series of high spatial resolution
photospheric intensity, vector magnetic field maps, and Doppler velocity
maps obtained with the Solar Optical Telescope aboard the Hinode
spacecraft. We conclude that the appearance and disappearance of the
Evershed flow and penumbra grains occur at nearly the same time and are
associated with changes of the inclination angle of the magnetic field
from vertical to more horizontal. This supports the idea that Evershed
flow is a result of thermal convection in the inclined field lines. The
dark core of the bright penumbral filament also appears coincidental
with the Evershed flow. However, the dark-cored bright filament
survives at least for 10-20 minutes after the disappearance of the
Evershed flow. The heat input into the bright filament continues even
after the end of heat transfer by the Evershed flow. This suggests that
local heating along the bright filament is important for maintaining
its brightness, in addition to heat transfer by the Evershed flow.
Title: Flat Fielding and Image Alignments for AIA/SDO Data Images
Authors: Shine, R. A.; Nightingale, R. W.; Boerner, P.; Tarbell,
T. D.; Wolfson, C. J.
Bibcode: 2010AGUFMSH23C1872S
Altcode:
The Atmospheric Imaging Assembly (AIA) on the NASA Solar Dynamics
Observatory (SDO) takes 4096 by 4096 CCD images of the sun in 10
wavelengths utilizing 4 telescopes and each wavelength channel requires
a flat field that is applied shortly after receipt of the data on the
ground. Although some useful information about the CCD's was obtained
pre-launch, most of the flat field computation must be done with solar
images taken in orbit. Raw flat field images are collected as out of
focus images at 14 offsets using PZT adjustments on each telescope
and then each wavelength group is processed together using the Kuhn,
Lin, and Loranz (1991) flat field algorithm. However, the PZT motions
are restricted to about 14 arc sec limiting the measurement of large
scale variations. Hence larger offsets are also used by adjusting
the space craft pointing. All of these suffer from changes in the
solar image between exposures (especially the larger offsets), low
counts in some channels, and reflections in the UV channels. These
make direct use of the flats unfeasible and instead we process them to
compute 6 separable effects: 1) differences in the CCD quad gains and
inner row/column effects, 2) a repeating pattern across the CCD from
the manufacturing process (dubbed "tire tracks"), 3) a grid pattern
in the extreme ultraviolet wavelengths from the back filter, 4)
blemishes (some are translucent and some are treated as bad pixels),
5) large scale vignetting, and 6) all other variations. The last
category includes all remaining flat field effects after the others
are removed. This has not been done well for any of the wavelengths
yet. These effects will be described and illustrated, as will the
before and after images resulting from applying the processed flat
fields. We also describe techniques for fitting the solar limb to
accurately determine image centers and radii. This is not a trivial
problem for the extreme ultraviolet images but is required to align
images, determine relative plate scales, and monitor pointing variations
related to thermal changes. All channels except the He II 304A can be
now be routinely measured with an rms error of typically less than 0.2
arc sec. This allows us to easily see the radius variations during the
24 hour orbit for example. The computer code requires about 3 seconds
(single threaded) for each measurement. This work was supported by
NASA under the SDO/AIA contract NNG04EA00C.
Title: Coordinated observations of solar prominences with Hinode/SOT
and SDO/AIA
Authors: Berger, T. E.; Tarbell, T. D.; Schrijver, C. J.; Title,
A. M.; Boerner, P.; Shine, R. A.
Bibcode: 2010AGUFMSH21C..04B
Altcode:
We show the first detailed study of a solar quiescent prominence
using simultaneous observations from the Hinode/SOT and SDO/AIA
instruments. The prominence studied is a polar crown prominence
located at the base of a large coronal cavity on the NW solar limb on
22-June-2010. Hinode observed the prominence for 2.75 hours running
the HOP 73 prominence observation program to acquire Ca II H-line
filtergrams and H-alpha doppler observations at a 20-second cadence. SOT
observations in Ca II H-line and H-alpha spectral lines reveal the
common dynamics of filamentary downflows and large-scale oscillations
of the prominence body. In addition a dark cavity is observed to
rise into the prominence and stagnate before going unstable to form
Rayleigh-Taylor plume upflows. AIA observations in the 304, 171, 193,
and 211 channels with 14 second cadence reveal that both the cavity
and the plume upflows are bright in these hotter passbands. Filter
ratio measurements as well as preliminary EM estimates imply that
the cavity and plume plasma temperature is at least 10^6 K. Plasma at
this temperature has never been detected or theorized in a confined
configuration in the lower chromosphere below a prominence. Assuming
an electron number density of 3e09 cm-3, the balance between thermal
pressure in the cavity and magnetic pressure in the overlying prominence
implies a magnetic flux density of order 10 gauss, in line with earlier
measurements of prominence magnetic fields. However the cavity likely
contains a significant magnetic energy density of its own implying that
the prominence magnetic fields may need to be significantly higher to
balance the cavity buoyancy. The existence of 10^6 K plasma confined
below a quiescent prominence and the subsequent onset of buoyancy
instabilities present new challenges to theories of prominence and
coronal cavity formation and suggest new avenues for supply of mass
and magnetic flux to the associated coronal cavity systems that make
up the bulk of CMEs. Hinode/SOT Ca II H-line image overlain on SDO/AIA
304A image of a quiescent solar prominence.
Title: Emergence of Helical Flux and the Formation of an Active
Region Filament Channel
Authors: Lites, B. W.; Kubo, M.; Berger, T.; Frank, Z.; Shine, R.;
Tarbell, T.; Title, A.; Okamoto, T. J.; Otsuji, K.
Bibcode: 2010ApJ...718..474L
Altcode:
We present comprehensive observations of the formation and evolution
of a filament channel within NOAA Active Region (AR) 10978 from
Hinode/Solar Optical Telescope and TRACE. We employ sequences
of Hinode spectro-polarimeter maps of the AR, accompanying Hinode
Narrowband Filter Instrument magnetograms in the Na I D1 line, Hinode
Broadband Filter Instrument filtergrams in the Ca II H line and G-band,
Hinode X-ray telescope X-ray images, and TRACE Fe IX 171 Å image
sequences. The development of the channel resembles qualitatively
that presented by Okamoto et al. in that many indicators point to
the emergence of a pre-existing sub-surface magnetic flux rope. The
consolidation of the filament channel into a coherent structure takes
place rapidly during the course of a few hours, and the filament form
then gradually shrinks in width over the following two days. Particular
to this filament channel is the observation of a segment along its
length of horizontal, weak (500 G) flux that, unlike the rest of the
filament channel, is not immediately flanked by strong vertical plage
fields of opposite polarity on each side of the filament. Because this
isolated horizontal field is observed in photospheric lines, we infer
that it is unlikely that the channel formed as a result of reconnection
in the corona, but the low values of inferred magnetic fill fraction
along the entire length of the filament channel suggest that the bulk
of the field resides somewhat above the low photosphere. Correlation
tracking of granulation in the G band presents no evidence for either
systematic flows toward the channel or systematic shear flows along
it. The absence of these flows, along with other indications of these
data from multiple sources, reinforces (but does not conclusively
demonstrate) the picture of an emerging flux rope as the origin of
this AR filament channel.
Title: Quiescent Prominence Dynamics Observed with the Hinode Solar
Optical Telescope. I. Turbulent Upflow Plumes
Authors: Berger, Thomas E.; Slater, Gregory; Hurlburt, Neal; Shine,
Richard; Tarbell, Theodore; Title, Alan; Lites, Bruce W.; Okamoto,
Takenori J.; Ichimoto, Kiyoshi; Katsukawa, Yukio; Magara, Tetsuya;
Suematsu, Yoshinori; Shimizu, Toshifumi
Bibcode: 2010ApJ...716.1288B
Altcode:
Hinode/Solar Optical Telescope (SOT) observations reveal two new
dynamic modes in quiescent solar prominences: large-scale (20-50 Mm)
"arches" or "bubbles" that "inflate" from below into prominences, and
smaller-scale (2-6 Mm) dark turbulent upflows. These novel dynamics are
related in that they are always dark in visible-light spectral bands,
they rise through the bright prominence emission with approximately
constant speeds, and the small-scale upflows are sometimes observed to
emanate from the top of the larger bubbles. Here we present detailed
kinematic measurements of the small-scale turbulent upflows seen in
several prominences in the SOT database. The dark upflows typically
initiate vertically from 5 to 10 Mm wide dark cavities between the
bottom of the prominence and the top of the chromospheric spicule
layer. Small perturbations on the order of 1 Mm or less in size
grow on the upper boundaries of cavities to generate plumes up to
4-6 Mm across at their largest widths. All plumes develop highly
turbulent profiles, including occasional Kelvin-Helmholtz vortex
"roll-up" of the leading edge. The flows typically rise 10-15 Mm before
decelerating to equilibrium. We measure the flowfield characteristics
with a manual tracing method and with the Nonlinear Affine Velocity
Estimator (NAVE) "optical flow" code to derive velocity, acceleration,
lifetime, and height data for several representative plumes. Maximum
initial speeds are in the range of 20-30 km s-1, which
is supersonic for a ~10,000 K plasma. The plumes decelerate in the
final few Mm of their trajectories resulting in mean ascent speeds
of 13-17 km s-1. Typical lifetimes range from 300 to 1000
s (~5-15 minutes). The area growth rate of the plumes (observed as
two-dimensional objects in the plane of the sky) is initially linear
and ranges from 20,000 to 30,000 km2 s-1 reaching
maximum projected areas from 2 to 15 Mm2. Maximum contrast of
the dark flows relative to the bright prominence plasma in SOT images
is negative and ranges from -10% for smaller flows to -50% for larger
flows. Passive scalar "cork movies" derived from NAVE measurements show
that prominence plasma is entrained by the upflows, helping to counter
the ubiquitous downflow streams in the prominence. Plume formation
shows no clear temporal periodicity. However, it is common to find
"active cavities" beneath prominences that can spawn many upflows in
succession before going dormant. The mean flow recurrence time in these
active locations is roughly 300-500 s (5-8 minutes). Locations remain
active on timescales of tens of minutes up to several hours. Using a
column density ratio measurement and reasonable assumptions on plume
and prominence geometries, we estimate that the mass density in the
dark cavities is at most 20% of the visible prominence density, implying
that a single large plume could supply up to 1% of the mass of a typical
quiescent prominence. We hypothesize that the plumes are generated from
a Rayleigh-Taylor instability taking place on the boundary between
the buoyant cavities and the overlying prominence. Characteristics,
such as plume size and frequency, may be modulated by the strength
and direction of the cavity magnetic field relative to the prominence
magnetic field. We conclude that buoyant plumes are a source of
quiescent prominence mass as well as a mechanism by which prominence
plasma is advected upward, countering constant gravitational drainage.
Title: High Velocity Horizontal Motions at the Edge of Sunspot
Penumbrae
Authors: Hagenaar-Daggett, Hermance J.; Shine, R.
Bibcode: 2010AAS...21640110H
Altcode: 2010BAAS...41R.858H
The outer edges of sunspot penumbrae have long been noted as a region
of interesting dynamics including formation of MMFs, extensions and
retractions of the penumbral tips, fast moving (2-3 km/s) bright
features dubbed"streakers", and localized regions of high speed
downflows interpreted as Evershed "sinks". Using 30s cadence movies of
high spatial resolution G band and Ca II H images taken by the Hinode
SOT/FPP instrument from 5-7 Jan 2007, we have been investigating the
penumbra around a sunspot in AR 10933. In addition to the expected
phenomena, we also see occasional small dark crescent-shaped features
with high horizontal velocities (6.5 km/s) in G band movies. These
appear to be emitted from penumbral tips. They travel about 1.5
Mm developing a bright wake that evolves into a slower moving
(1-2 km/s) bright feature. In some cases, there may be an earlier
outward propagating disturbance within the penumbra. We have also
analyzed available Fe 6302 Stokes V images to obtain information on
the magnetic field. Although only lower resolution 6302 images made
with a slower cadence are available for these particular data sets,
we can establish that the features have the opposite magnetic polarity
of the sunspot. This observation may be in agreement with simulations
showing that a horizontal flux tube develops crests that move outward
with a velocity as large as 10 km/s. This work was supported by
NASA contract NNM07AA01C.
Title: Is Flux Submergence an Essential Aspect of Flux Emergence?
Authors: Lites, B. W.; Frank, Z.; Shine, R. A.; Title, A. M.;
Ichimoto, K.
Bibcode: 2009ASPC..415..172L
Altcode:
High resolution Hinode Spectro-Polarimeter observations permit one
to examine the detailed structure of the magnetic field vector in
emerging flux regions. We find the field to have a concave-upward
geometry on the smallest scales observed (0.3 arcsec), indicating the
presence of U-loops at the sites of approaching and canceling opposite
polarities. This structure suggests that reconnection is taking place
at or below the surface, allowing the emerging flux to rid itself of
its considerable mass burden. Supersonic down flows are often observed
adjacent to, but not coincident with, the sites of canceling flux. We
propose that these are the sites that drain the mass contained in the
buoyantly-rising flux elements. The observations then suggest a process
of sub-surface reconnection producing O-loops that then are forced to
descend with the intergranular convective down flows, thus making flux
submergence important to the larger scale flux emergence process.
Title: Moving Magnetic Features and the Flow Pattern around Sunspots
Authors: Hagenaar, H. J.; Shine, R. A.
Bibcode: 2009AGUFMSH51A1255H
Altcode:
Studies of Moving Magnetic Features indicate a Spoke Pattern around
Sunspots. We investigate this flow pattern further on Hinode/ SOT data.
Title: Helical Shape and Twisting Motion as Intrinsic Properties of
Penumbral Filaments
Authors: Shine, R. A.; Ryutova, M.; Berger, T. E.; Title, A. M.;
Tarbell, T. D.; Ichimoto, K.
Bibcode: 2009AGUFMSH23B1541S
Altcode:
A wealth of high resolution data obtained with advanced ground based
telescopes and the SOT instrument on HINODE have led to new findings
in the properties of penumbral filaments and controversies in their
interpretation. Here we address one such issue, namely the question of
whether the apparent twist of filaments is real or is just a viewing
effect. We show that the helical shape and twisting motions of penumbral
filaments follow from first principles and represent an integral part of
penumbra formation and dynamics. As such, these properties link together
other observed features of filaments including their magnetic and
thermal substructure and their impact on the overlying atmosphere. At
all stages of penumbral dynamics, qualitative agreement of theory and
observations is supported by quantitative analysis as well.
Title: A New View of Fine Scale Dynamics and Magnetism of Sunspots
Revealed by Hinode/SOT
Authors: Ichimoto, K.; Suematsu, Y.; Katsukawa, Y.; Tsuneta, S.;
Shimojo, M.; Shimizu, T.; Shine, R. A.; Tarbell, T. D.; Berger, T.;
Title, A. M.; Lites, B. W.; Kubo, M.; Yokoyama, T.; Nagata, S.
Bibcode: 2009ASPC..405..167I
Altcode:
The Solar Optical Telescope on-board Hinode is providing a new view of
the fine scale dynamics in sunspots with its high spatial resolution and
unprecedented image stability. We present three features related to the
Evershed flow each of which raises a new puzzle in sunspot dynamics;
i.e., twisting appearance of penumbral filaments, the source and sink
of individual Evershed flow channels, and the net circular polarization
in penumbrae with its spatial relation to the Evershed flow channels.
Title: Has Hinode Revealed the Missing Turbulent Flux of the
Quiet Sun?
Authors: Lites, B. W.; Kubo, M.; Socas-Navarro, H.; Berger, T.; Frank,
Z.; Shine, R.; Tarbell, T.; Title, A. M.; Ichimoto, K.; Katsukawa,
Y.; Tsuneta, S.; Suematsu, Y.; Shimizu, T.; Nagata, S.
Bibcode: 2009ASPC..405..173L
Altcode:
The Hinode Spectro-Polarimeter has revealed the presence of surprisingly
strong horizontal magnetic fields nearly everywhere in the quiet
solar atmosphere. These horizontal fields, along with measures of the
vertical fields, may be the signature of the ``hidden turbulent flux''
of the quiet Sun. The measured horizontal fields average at least to
55 Gauss: nearly 5 times that of the measured longitudinal apparent
flux density. The nature of these fields are reviewed, and discussed
in the light of recent magneto-convection numerical simulations of
the quiet Sun.
Title: Hinode Observation of the Magnetic Fields in a Sunspot Light
Bridge Accompanied by Long-Lasting Chromospheric Plasma Ejections
Authors: Shimizu, Toshifumi; Katsukawa, Yukio; Kubo, Masahito; Lites,
Bruce W.; Ichimoto, Kiyoshi; Suematsu, Yoshinori; Tsuneta, Saku;
Nagata, Shin'ichi; Shine, Richard A.; Tarbell, Theodore D.
Bibcode: 2009ApJ...696L..66S
Altcode:
We present high-resolution magnetic field measurements of a sunspot
light bridge (LB) that produced chromospheric plasma ejections
intermittently and recurrently for more than 1 day. The observations
were carried out with the Hinode Solar Optical Telescope on 2007
April 29 and 30. The spectro-polarimeter reveals obliquely oriented
magnetic fields with vertical electric current density higher than
100 mA m-2 along the LB. The observations suggest that
current-carrying highly twisted magnetic flux tubes are trapped below
a cusp-shaped magnetic structure along the LB. The presence of trapped
current-carrying flux tubes is essential for causing long-lasting
chromospheric plasma ejections at the interface with pre-existing
vertically oriented umbral fields. A bidirectional jet was clearly
detected, suggesting magnetic reconnections occurring at very low
altitudes, slightly above the height where the vector magnetic fields
are measured. Moreover, we found another strong vertical electric
current on the interface between the current-carrying flux tube
and pre-existing umbral field, which might be a direct detection
of the currents flowing in the current sheet formed at the magnetic
reconnection sites.
Title: Magnetic Feature Tracking in Sunspot Moats Using Hinode/SOT
Observations
Authors: Hagenaar-Daggett, Hermance J.; Shine, R. A.; Tarbell, T. D.
Bibcode: 2009SPD....40.0908H
Altcode:
A long series of continuous observations of NOAA AR 10933 taken
by Hinode/SOT from 2-4 January, 2007 is used to study MMF's (moving
magnetic features) in the periphery of the large sunspot in the region
and its surrounding moat. We describe some algorithms we have developed
to quickly recognize and track discrete features and apply these to
the magnetic structures seen in Na I 589.6nm Stokes V images. Because
the features evolve and show variable visibilty, automatic tracking is
not always successful even with the seeing free Hinode images and we
are still attempting to improve our techniques. We also compute flow
maps from the photospheric G band images using LCT (local correlation
tracking) to compare with the generally faster MMF motions. This
work was supported by NASA contract NNM07AA01C.
Title: Prominence Formation Associated with an Emerging Helical
Flux Rope
Authors: Okamoto, Takenori J.; Tsuneta, Saku; Lites, Bruce W.; Kubo,
Masahito; Yokoyama, Takaaki; Berger, Thomas E.; Ichimoto, Kiyoshi;
Katsukawa, Yukio; Nagata, Shin'ichi; Shibata, Kazunari; Shimizu,
Toshifumi; Shine, Richard A.; Suematsu, Yoshinori; Tarbell, Theodore
D.; Title, Alan M.
Bibcode: 2009ApJ...697..913O
Altcode: 2009arXiv0904.0007O
The formation and evolution process and magnetic configuration of
solar prominences remain unclear. In order to study the formation
process of prominences, we examine continuous observations of a
prominence in NOAA AR 10953 with the Solar Optical Telescope on
the Hinode satellite. As reported in our previous Letter, we find
a signature suggesting that a helical flux rope emerges from below
the photosphere under a pre-existing prominence. Here we investigate
more detailed properties and photospheric indications of the emerging
helical flux rope, and discuss their relationship to the formation of
the prominence. Our main conclusions are: (1) a dark region with absence
of strong vertical magnetic fields broadens and then narrows in Ca II
H-line filtergrams. This phenomenon is consistent with the emergence
of the helical flux rope as photospheric counterparts. The size of the
flux rope is roughly 30,000 km long and 10,000 km wide. The width is
larger than that of the prominence. (2) No shear motion or converging
flows are detected, but we find diverging flows such as mesogranules
along the polarity inversion line. The presence of mesogranules may
be related to the emergence of the helical flux rope. (3) The emerging
helical flux rope reconnects with magnetic fields of the pre-existing
prominence to stabilize the prominence for the next several days. We
thus conjecture that prominence coronal magnetic fields emerge in
the form of helical flux ropes that contribute to the formation and
maintenance of the prominence.
Title: The Magnetic Landscape of the Sun's Polar Region
Authors: Tsuneta, S.; Ichimoto, K.; Katsukawa, Y.; Lites, B. W.;
Matsuzaki, K.; Nagata, S.; Orozco Suárez, D.; Shimizu, T.; Shimojo,
M.; Shine, R. A.; Suematsu, Y.; Suzuki, T. K.; Tarbell, T. D.; Title,
A. M.
Bibcode: 2008ApJ...688.1374T
Altcode: 2008arXiv0807.4631T
We present observations of the magnetic landscape of the polar region
of the Sun that are unprecedented in terms of spatial resolution,
field of view, and polarimetric precision. They were carried out with
the Solar Optical Telescope aboard Hinode. Using a Milne-Eddington
inversion, we find many vertically oriented magnetic flux tubes
with field strengths as strong as 1 kG scattered in latitude between
70° and 90°. They all have the same polarity, consistent with the
global polarity of the polar region. The field vectors are observed to
diverge from the centers of the flux elements, consistent with a view
of magnetic fields that are expanding and fanning out with height. The
polar region is also found to have ubiquitous horizontal fields. The
polar regions are the source of the fast solar wind, which is channeled
along unipolar coronal magnetic fields whose photospheric source is
evidently rooted in the strong-field, vertical patches of flux. We
conjecture that vertical flux tubes with large expansion around the
photospheric-coronal boundary serve as efficient chimneys for Alfvén
waves that accelerate the solar wind.
Title: Magnetic Fields of the Quiet Sun: A New Quantitative
Perspective From Hinode
Authors: Lites, B. W.; Kubo, M.; Socas-Navarro, H.; Berger, T.; Frank,
Z.; Shine, R.; Tarbell, T.; Title, A.; Ichimoto, K.; Katsukawa, Y.;
Tsuneta, S.; Suematsu, Y.; Shimizu, T.; Nagata, S.
Bibcode: 2008ASPC..397...17L
Altcode:
This article summarizes results of studies presented in two papers
already published: Lites et al. (2007a); Lites et al. (2007b). Please
see these for further details.
Title: On-orbit Performance of the Solar Optical Telescope aboard
Hinode
Authors: Ichimoto, K.; Katsukawa, Y.; Tarbell, T.; Shine, R. A.;
Hoffmann, C.; Berger, T.; Cruz, T.; Suematsu, Y.; Tsuneta, S.; Shimizu,
T.; Lites, B. W.
Bibcode: 2008ASPC..397....5I
Altcode: 2008arXiv0804.3248I
On-orbit performance of the Solar Optical Telescope (SOT) aboard Hinode
is described with some attention to its unpredicted aspects. In general,
SOT reveals an excellent performance and has been providing outstanding
data. Some unexpected features exist, however, in behaviours of the
focus position, throughput and structural stability. Most of them are
recovered by the daily operation i.e., frequent focus adjustment,
careful heater setting and corrections in data analysis. The
tunable filter contains air bubbles which degrade the data quality
significantly. Schemes for tuning the filter without disturbing the
bubbles have been developed and tested, and some useful procedures
to obtain Dopplergrams and magnetograms are now available. October
and March, when the orbit of satellite becomes nearly perpendicular
to the direction towards the Sun, provide a favourable condition for
continuous runs of the narrow-band filter imager.
Title: High Resolution Observations of Spicules with Hinode/SOT
Authors: Suematsu, Y.; Ichimoto, K.; Katsukawa, Y.; Shimizu, T.;
Okamoto, T.; Tsuneta, S.; Tarbell, T.; Shine, R. A.
Bibcode: 2008ASPC..397...27S
Altcode:
High time cadence unprecedented images at the limb with Ca II H line
filtergraph from the Solar Optical Telescope (SOT) aboard Hinode
have revealed that a spicule consists of highly dynamic multi-threads
(typically twin) as thin as a few tenths of an arcsecond, and shows
prominent lateral movement or oscillation with rotation on its axis
during its life. This multi-thread structure and lateral motion indicate
that the spicules can be driven by magnetic reconnection at unresolved
spatial scales at their footpoints.
Title: Evolution of Magnetic Fields at the Boundary of the Penumbra
Authors: Kubo, M.; Ichimoto, K.; Shimizu, T.; Lites, B. W.; Tsuneta,
S.; Suematsu, Y.; Katsukawa, Y.; Nagata, S.; Tarbell, T.; Shine,
R. A.; Title, A. M.
Bibcode: 2008ASPC..397...79K
Altcode:
The formation of moving magnetic features (MMFs) separating from the
penumbra were successfully observed with the Solar Optical Telescope
(SOT) aboard the Hinode satellite. We find that bright features in
the outer penumbra are located at the penumbral spines, which have
magnetic fields more vertical than the surroundings, or located at the
MMFs separating from the spines. This suggests that convection in the
outer penumbra is related to the disintegration of the sunspot.
Title: Disintegration of Magnetic Flux in Decaying Sunspots as
Observed with the Hinode SOT
Authors: Kubo, M.; Lites, B. W.; Ichimoto, K.; Shimizu, T.; Suematsu,
Y.; Katsukawa, Y.; Tarbell, T. D.; Shine, R. A.; Title, A. M.; Nagata,
S.; Tsuneta, S.
Bibcode: 2008ApJ...681.1677K
Altcode: 2008arXiv0806.0415K
Continuous observations of sunspot penumbrae with the Solar Optical
Telescope aboard Hinode clearly show that the outer boundary of the
penumbra fluctuates around its averaged position. The penumbral outer
boundary moves inward when granules appear in the outer penumbra. We
discover that such granules appear one after another while moving
magnetic features (MMFs) are separating from the penumbral "spines"
(penumbral features that have fields that are stronger and more vertical
than those of their surroundings). These granules that appear in the
outer penumbra often merge with bright features inside the penumbra
that move with the spines as they elongate toward the moat region. This
suggests that convective motions around the penumbral outer boundary are
related to the disintegration of magnetic flux in the sunspot. We also
find that dark penumbral filaments frequently elongate into the moat
region in the vicinity of MMFs that detach from penumbral spines. Such
elongating dark penumbral filaments correspond to nearly horizontal
fields extending from the penumbra. Pairs of MMFs with positive and
negative polarities are sometimes observed along the elongating dark
penumbral filaments. This strongly supports the notion that such
elongating dark penumbral filaments have magnetic fields with a "sea
serpent"-like structure. Evershed flows, which are associated with the
penumbral horizontal fields, may be related to the detachment of the
MMFs from the penumbral spines, as well as to the formation of the MMFs
along the dark penumbral filaments that elongate into the moat region.
Title: Polarization Calibration of the Solar Optical Telescope
onboard Hinode
Authors: Ichimoto, K.; Lites, B.; Elmore, D.; Suematsu, Y.; Tsuneta,
S.; Katsukawa, Y.; Shimizu, T.; Shine, R.; Tarbell, T.; Title, A.;
Kiyohara, J.; Shinoda, K.; Card, G.; Lecinski, A.; Streander, K.;
Nakagiri, M.; Miyashita, M.; Noguchi, M.; Hoffmann, C.; Cruz, T.
Bibcode: 2008SoPh..249..233I
Altcode: 2008SoPh..tmp...69I
The Solar Optical Telescope (SOT) onboard Hinode aims to obtain vector
magnetic fields on the Sun through precise spectropolarimetry of
solar spectral lines with a spatial resolution of 0.2 - 0.3 arcsec. A
photometric accuracy of 10−3 is achieved and, after the
polarization calibration, any artificial polarization from crosstalk
among Stokes parameters is required to be suppressed below the level
of the statistical noise over the SOT's field of view. This goal was
achieved by the highly optimized design of the SOT as a polarimeter,
extensive analyses and testing of optical elements, and an end-to-end
calibration test of the entire system. In this paper we review both
the approach adopted to realize the high-precision polarimeter of the
SOT and its final polarization characteristics.
Title: Image Stabilization System for Hinode (Solar-B) Solar Optical
Telescope
Authors: Shimizu, T.; Nagata, S.; Tsuneta, S.; Tarbell, T.; Edwards,
C.; Shine, R.; Hoffmann, C.; Thomas, E.; Sour, S.; Rehse, R.; Ito,
O.; Kashiwagi, Y.; Tabata, M.; Kodeki, K.; Nagase, M.; Matsuzaki,
K.; Kobayashi, K.; Ichimoto, K.; Suematsu, Y.
Bibcode: 2008SoPh..249..221S
Altcode:
The Hinode Solar Optical Telescope (SOT) is the first space-borne
visible-light telescope that enables us to observe magnetic-field
dynamics in the solar lower atmosphere with 0.2 - 0.3 arcsec spatial
resolution under extremely stable (seeing-free) conditions. To achieve
precise measurements of the polarization with diffraction-limited
images, stable pointing of the telescope (<0.09 arcsec, 3σ) is
required for solar images exposed on the focal plane CCD detectors. SOT
has an image stabilization system that uses image displacements
calculated from correlation tracking of solar granules to control
a piezo-driven tip-tilt mirror. The system minimizes the motions
of images for frequencies lower than 14 Hz while the satellite and
telescope structural design damps microvibration in higher frequency
ranges. It has been confirmed from the data taken on orbit that
the remaining jitter is less than 0.03 arcsec (3σ) on the Sun. This
excellent performance makes a major contribution to successful precise
polarimetric measurements with 0.2 - 0.3 arcsec resolution.
Title: The Solar Optical Telescope for the Hinode Mission: An Overview
Authors: Tsuneta, S.; Ichimoto, K.; Katsukawa, Y.; Nagata, S.; Otsubo,
M.; Shimizu, T.; Suematsu, Y.; Nakagiri, M.; Noguchi, M.; Tarbell,
T.; Title, A.; Shine, R.; Rosenberg, W.; Hoffmann, C.; Jurcevich,
B.; Kushner, G.; Levay, M.; Lites, B.; Elmore, D.; Matsushita, T.;
Kawaguchi, N.; Saito, H.; Mikami, I.; Hill, L. D.; Owens, J. K.
Bibcode: 2008SoPh..249..167T
Altcode: 2008SoPh..tmp...74T; 2007arXiv0711.1715T
The Solar Optical Telescope (SOT) aboard the Hinode satellite
(formerly called Solar-B) consists of the Optical Telescope Assembly
(OTA) and the Focal Plane Package (FPP). The OTA is a 50-cm
diffraction-limited Gregorian telescope, and the FPP includes the
narrowband filtergraph (NFI) and the broadband filtergraph (BFI), plus
the Stokes Spectro-Polarimeter (SP). The SOT provides unprecedented
high-resolution photometric and vector magnetic images of the
photosphere and chromosphere with a very stable point spread function
and is equipped with an image-stabilization system with performance
better than 0.01 arcsec rms. Together with the other two instruments
on Hinode (the X-Ray Telescope (XRT) and the EUV Imaging Spectrometer
(EIS)), the SOT is poised to address many fundamental questions about
solar magnetohydrodynamics. This paper provides an overview; the
details of the instrument are presented in a series of companion papers.
Title: Frequent Occurrence of High-Speed Local Mass Downflows on
the Solar Surface
Authors: Shimizu, T.; Lites, B. W.; Katsukawa, Y.; Ichimoto, K.;
Suematsu, Y.; Tsuneta, S.; Nagata, S.; Kubo, M.; Shine, R. A.; Tarbell,
T. D.
Bibcode: 2008ApJ...680.1467S
Altcode: 2008arXiv0804.1167S
We report on new spectropolarimetric measurements with simultaneous
filter imaging observation, revealing the frequent appearance of
polarization signals indicating high-speed, probably supersonic,
downflows that are associated with at least three different
configurations of magnetic fields in the solar photosphere. The
observations were carried out with the Solar Optical Telescope on
board the Hinode satellite. High-speed downflows are excited when a
moving magnetic feature is newly formed near the penumbral boundary of
sunspots. Also, a new type of downflows is identified at the edge of
sunspot umbra that lack accompanying penumbral structures. These may
be triggered by the interaction of magnetic fields swept by convection
with well-concentrated magnetic flux. Another class of high-speed
downflows are observed in quiet Sun and sunspot moat regions. These are
closely related to the formation of small concentrated magnetic flux
patches. High-speed downflows of all types are transient time-dependent
mass motions. These findings suggest that the excitation of supersonic
mass flows are one of the key observational features of the dynamical
evolution occurring in magnetic-field fine structures on the solar
surface.
Title: Cooperative Observation of Ellerman Bombs between the Solar
Optical Telescope aboard Hinode and Hida/Domeless Solar Telescope
Authors: Matsumoto, Takuma; Kitai, Reizaburo; Shibata, Kazunari;
Nagata, Shin'ichi; Otsuji, Kenichi; Nakamura, Tahei; Watanabe, Hiroko;
Tsuneta, Saku; Suematsu, Yoshinori; Ichimoto, Kiyoshi; Shimizu,
Toshifumi; Katsukawa, Yukio; Tarbell, Theodore D.; Lites, Bruce W.;
Shine, Richard A.; Title, Alan M.
Bibcode: 2008PASJ...60..577M
Altcode:
High-resolution CaIIH broad-band filter images of NOAA10933 on 2007
January 5 were obtained by the Solar Optical Telescope aboard the Hinode
satellite. Many small-scale (∼1") bright points were observed outside
the sunspot and inside the emerging flux region. We identified some of
these bright points with Ellerman bombs (EBs) by using Hα images taken
by the Domeless Solar Telescope at Hida observatory. The sub-arcsec
structures of two EBs seen in CaIIH were studied in detail. Our
observation showed the following two aspects: (1) The CaIIH bright
points identified with EBs were associated with the bipolar magnetic
field structures, as reported by previous studies. (2)The structure
of the CaIIH bright points turned out to consist of the following two
parts: a central elongated bright core (0.7" × 0.5") located along
the magnetic neutral line and a diffuse halo (1.2"×1.8").
Title: Emergence of a helical flux rope and prominence formation
Authors: Okamoto, T. J.; Tsuneta, S.; Lites, B. W.; Kubo, M.; Yokoyama,
T.; Berger, T. E.; Ichimoto, K.; Katsukawa, Y.; Nagata, S.; Shibata,
K.; Shimizu, T.; Shine, R. A.; Suematsu, Y.; Tarbell, T. D.; Title,
A. M.
Bibcode: 2008AGUSMSP43B..06O
Altcode:
We report a discovery about emergence of a helical flux rope. The
episode may be related to the formation and evolution of an active
region prominence. Statistical studies by previous authors indicate that
numerous prominences have the inverse-polarity configuration suggesting
the helical magnetic configurations. There are two theoretical
models about formation of such a coronal helical magnetic field in
association with prominences: flux rope model and sheared-arcade
model. We have so far no clear observational evidence to support
either model. In order to find a clue about the formation of the
prominence, we had continuous observations of NOAA AR 10953 with the
SOT during 2007 April 28 to May 9. A prominence was located over the
polarity inversion line in the south-east of the main sunspot. These
observations provided us with a time series of vector magnetic fields
on the photosphere under the prominence. We found four new features:
(1) The abutting opposite-polarity regions on the two sides along
the polarity inversion line first grew laterally in size and then
narrowed. (2) These abutting regions contained vertically-weak,
but horizontally-strong magnetic fields. (3) The orientations of
the horizontal magnetic fields along the polarity inversion line on
the photosphere gradually changed with time from a normal- polarity
configuration to an inverse-polarity one. (4) The horizontal-magnetic
field region was blueshifted. These indicate that helical flux rope
emerges from below the photosphere into the corona along the polarity
inversion line under the prominence. We suggest that this supply of a
helical magnetic flux possibly into the corona is related to formation
and maintenance of active-region prominences.
Title: Photospheric Signature of Penumbral Microjets
Authors: Katsukawa, Y.; Jurcak, J.; Ichimoto, K.; Suemtasu, Y.;
Tsuneta, S.; Shimizu, T.; Berger, T. E.; Shine, R. A.; Tarbell, T. D.;
Lites, B. W.
Bibcode: 2008AGUSMSP53A..03K
Altcode:
HINODE Solar Optical Telescope (SOT) discovered ubiquitous occurrence
of fine-scale jetlike activities in penumbral chromospheres, which
are referred to as penumbral microjets. The microjets' small width
of 400 km and short duration of less than 1 min make them difficult
to identify in existing ground-based observations. The apparent
rise velocity is faster than 50km/s and is roughly comparable to
the Alfven speed in the sunspot chromosphere. These properties of
penumbral microjets suggest that magnetic reconnection in uncombed
magnetic field configuration is the most possible cause of penumbral
microjets. In order to understand magnetic configuration associated with
penumbral microjets and prove the chromospheric magnetic reconnection
hypothesis, we investigated relationship between penumbral microjets
seen in CaIIH images and photospheric magnetic fields measured by
the HINODE spectro-polarimeter. We found the inclination angles of
penumbral microjets measured in CaII H images are roughly consistent
with inclination angles of relatively vertical magnetic field
component in uncombed magnetic field configuration. In addition,
strong and transient downflows are observed in the photosphere near
the boundary of a horizontal flux tube associated with a penumbral
microjet. The size of the downflow region is about 300km, which is
close to the width of penumbral microjets seen in CaII H images. The
downflow velocity of several km/s might be a result of an outflow of
chromospheric magnetic reconnection and suffer deceleration due to
the higher density in the photosphere.
Title: Evolution of Evershed and Shear Flows Associated With the
X3.4 Flare of December 13, 2006
Authors: Tan, C.; Shine, R. A.; Abramenko, V. I.; Wang, H.
Bibcode: 2008AGUSMSP51C..03T
Altcode:
Liu et al. (2006) presented the observation of rapid penumbra decay
associated with a number of X-class flares. As the Evershed flows
are closely associated with morphology of sunspot penumbra, in this
work, we use the state-of-art Hinode data to track Evershed flow in
flaring active regions as well as shear flows close to the flaring
neutral line. This paper concentrates on the study of AR10930 around
the time of the X3.4 flare time on December 13, 2006. We utilize the
seeing-free data from Hinode SOT G-band data as the tracer to obtain
the horizontal component of the Evershed flows by local correlation
tracking. We find that: (1) The penumbra decay appears obviously in
this active region associated with the X3.4 flare. (2) The Evershed
flow decreases slightly immediately following the flare, indicating
that magnetic fields become more vertical associated with the flare. In
addition, we will discuss the evolution of shear flows near the neutral
line of this delta spot leading to and following the flare.
Title: Sources and Sinks of the Evershed Flow
Authors: Shine, R. A.; Title, A. M.; Ichimoto, K.; Lites, B.
Bibcode: 2008AGUSMSP31A..01S
Altcode:
Extending the work of Ichimoto et al (2007), we investigate the sources
and sinks of the Evershed flow in sunspot penumbra using data from the
Solar Optical Telescope (SOT) instruments on the Hinode satellite. We
use spectral maps taken with the Spectro-Polarimeter (SP) that provide
detailed snapshots of the large sunspot in AR 10930 over a range
of viewing angles as it rotated across the solar disk in December
2006. These are supplemented by images taken with the Filtergraph
(FG) instrument that show the dynamics of the structures. AR 10930 has
some large sunspots showing sources and sinks within the penumbra as
well as near the inner and outer boundaries. There are also regions
of contact between penumbra of two sunspots (of opposite magnetic
polarity) that show stronger horizontal flows and downdrafts than seen
elsewhere in the penumbras. The relationship between Evershed "clouds"
showing quasi-periodic variations in the spatially averaged Evershed
flow and the penumbral fine structures is also investigated. This work
was supported by NASA contract NNM07AA01C.
Title: Disintegration of Magnetic Flux in Decaying Sunspots as
Observed with the Hinode/SOT
Authors: Kubo, M.; Lites, B. W.; Ichimoto, K.; Shimizu, T.; Suematsu,
Y.; Katsukawa, Y.; Tarbell, T. D.; Shine, R. A.; Title, A. M.; Nagata,
S.; Tsuneta, S.
Bibcode: 2008AGUSMSP31B..01K
Altcode:
Continuous observations of sunspot penumbrae with the Solar Optical
Telescope aboard Hinode clearly show that the outer boundary of the
penumbra fluctuates around its averaged position. The penumbral outer
boundary moves inward when granules appear in the outer penumbra. We
discover that such granules appear one after another while moving
magnetic features (MMFs) are separating from the penumbral "spines"
(penumbral features having fields that are stronger and more vertical
than their surroundings). These granules that appear in the outer
penumbra often merge with bright features inside the penumbra that move
with spines as they elongate toward the moat region. This suggests that
convective motions around the penumbral outer boundary are related to
disintegration of magnetic flux in the sunspot. We also find that dark
penumbral filaments frequently elongate into the moat region in the
vicinity of MMFs that detach from penumbral spines. Such elongating
dark penumbral filaments correspond to nearly horizontal fields
extending from the penumbra. Pairs of MMFs with positive and negative
polarities are sometimes observed along the elongating dark penumbral
filaments. This strongly supports the notion that such elongating dark
penumbral filaments have magnetic fields with a "sea serpent"-like
structure. Evershed flows, which are associated with the penumbral
horizontal fields, may be related to detachment of the MMFs from the
penumbral spines, as well as to the formation of the MMFs along the
dark penumbral filaments that elongate into the moat region.
Title: Formation of Solar Magnetic Flux Tubes with Kilogauss Field
Strength Induced by Convective Instability
Authors: Nagata, Shin'ichi; Tsuneta, Saku; Suematsu, Yoshinori;
Ichimoto, Kiyoshi; Katsukawa, Yukio; Shimizu, Toshifumi; Yokoyama,
Takaaki; Tarbell, Theodore D.; Lites, Bruce W.; Shine, Richard A.;
Berger, Thomas E.; Title, Alan M.; Bellot Rubio, Luis R.; Orozco
Suárez, David
Bibcode: 2008ApJ...677L.145N
Altcode:
Convective instability has been a mechanism used to explain
the formation of solar photospheric flux tubes with kG field
strength. However, the turbulence of the Earth's atmosphere has
prevented ground-based observers from examining the hypothesis
with precise polarimetric measurement on the subarcsecond scale
flux tubes. Here we discuss observational evidence of this scenario
based on observations with the Solar Optical Telescope (SOT) aboard
Hinode. The cooling of an equipartition field strength flux tube
precedes a transient downflow reaching 6 km s-1 and the
intensification of the field strength to 2 kG. These observations
agree very well with the theoretical predictions.
Title: Transient horizontal magnetic fields in solar plage regions
Authors: Ishikawa, R.; Tsuneta, S.; Ichimoto, K.; Isobe, H.; Katsukawa,
Y.; Lites, B. W.; Nagata, S.; Shimizu, T.; Shine, R. A.; Suematsu,
Y.; Tarbell, T. D.; Title, A. M.
Bibcode: 2008A&A...481L..25I
Altcode: 2008arXiv0802.1769I
Aims:We report the discovery of isolated, small-scale emerging
magnetic fields in a plage region with the Solar Optical Telescope
aboard Hinode.
Methods: Spectro-polarimetric observations were
carried out with a cadence of 34 s for the plage region located near
disc center. The vector magnetic fields are inferred by Milne-Eddington
inversion.
Results: The observations reveal widespread occurrence
of transient, spatially isolated horizontal magnetic fields. The
lateral extent of the horizontal magnetic fields is comparable to
the size of photospheric granules. These horizontal magnetic fields
seem to be tossed about by upflows and downflows of the granular
convection. We also report an event that appears to be driven by the
magnetic buoyancy instability. We refer to buoyancy-driven emergence
as type 1 and convection-driven emergence as type 2. Although both
events have magnetic field strengths of about 600 G, the filling
factor of type 1 is a factor of two larger than that of type 2.
Conclusions: Our finding suggests that the granular convection in
the plage regions is characterized by a high rate of occurrence of
granular-sized transient horizontal fields.
Title: Net circular polarization of sunspots in high spatial
resolution
Authors: Ichimoto, K.; Tsuneta, S.; Suematsu, Y.; Katsukawa, Y.;
Shimizu, T.; Lites, B. W.; Kubo, M.; Tarbell, T. D.; Shine, R. A.;
Title, A. M.; Nagata, S.
Bibcode: 2008A&A...481L...9I
Altcode:
Context: Net circular polarization (NCP) of spectral lines in
sunspots has been most successfully explained by the presense of
discontinuities in the magnetic field inclination and flow velocity
along the line-of-sight in the geometry of the embedded flux tube model
of penumbrae (Δγ-effect).
Aims: The fine scale structure of
NCP in a sunspot is examined with special attention paid to spatial
relations of the Evershed flow to confirm the validity of the present
interpretation of the NCP of sunspots.
Methods: High resolution
spectro-polarimetric data of a positive-polarity sunspot obtained
by the Solar Optical Telescope aboard Hinode are analysed.
Results: A positive NCP is associated with the Evershed flow
channels in both limb-side and disk center-side penumbrae and with
upflows in the penumbra at disk center. The negative NCP in the disk
center-side penumbra is generated in inter-Evershed flow channels.
Conclusions: The first result is apparently inconsistent with the
current explanation of NCP with the Δγ-effect but rather suggests a
positive correlation between the magnetic field strength and the flow
velocity as the cause of the NCP. The second result serves as strong
evidence for the presence of gas flows in inter-Evershed flow channels.
Title: Hinode SOT Observations of Solar Quiescent Prominence Dynamics
Authors: Berger, Thomas E.; Shine, Richard A.; Slater, Gregory L.;
Tarbell, Theodore D.; Title, Alan M.; Okamoto, Takenori J.; Ichimoto,
Kiyoshi; Katsukawa, Yukio; Suematsu, Yoshinori; Tsuneta, Saku; Lites,
Bruce W.; Shimizu, Toshifumi
Bibcode: 2008ApJ...676L..89B
Altcode:
We report findings from multihour 0.2'' resolution movies of
solar quiescent prominences (QPs) observed with the Solar Optical
Telescope (SOT) on the Hinode satellite. The observations verify
previous findings of filamentary downflows and vortices in QPs. SOT
observations also verify large-scale transverse oscillations in QPs,
with periods of 20-40 minutes and amplitudes of 2-5 Mm. The upward
propagation speed of several waves is found to be ~10 km s-1,
comparable to the sound speed of a 10,000 K plasma, implying that
the waves are magnetoacoustic in origin. Most significantly, Hinode
SOT observations reveal that dark, episodic upflows are common in
QPs. The upflows are 170-700 km in width, exhibit turbulent flow,
and rise with approximately constant speeds of ~20 km s-1
from the base of the prominence to heights of ~10-20 Mm. The upflows
are visible in both the Ca II H-line and Hα bandpasses of SOT. The new
flows are seen in about half of the QPs observed by SOT to date. The
dark upflows resemble buoyant starting plumes in both their velocity
profile and flow structure. We discuss thermal and magnetic mechanisms
as possible causes of the plumes.
Title: Emergence of a Helical Flux Rope under an Active Region
Prominence
Authors: Okamoto, Takenori J.; Tsuneta, Saku; Lites, Bruce W.; Kubo,
Masahito; Yokoyama, Takaaki; Berger, Thomas E.; Ichimoto, Kiyoshi;
Katsukawa, Yukio; Nagata, Shin'ichi; Shibata, Kazunari; Shimizu,
Toshifumi; Shine, Richard A.; Suematsu, Yoshinori; Tarbell, Theodore
D.; Title, Alan M.
Bibcode: 2008ApJ...673L.215O
Altcode: 2008arXiv0801.1956O
Continuous observations were obtained of NOAA AR 10953 with the Solar
Optical Telescope (SOT) on board the Hinode satellite from 2007 April
28 to May 9. A prominence was located over the polarity inversion
line (PIL) to the southeast of the main sunspot. These observations
provided us with a time series of vector magnetic fields on the
photosphere under the prominence. We found four features: (1) The
abutting opposite-polarity regions on the two sides along the PIL first
grew laterally in size and then narrowed. (2) These abutting regions
contained vertically weak but horizontally strong magnetic fields. (3)
The orientations of the horizontal magnetic fields along the PIL on
the photosphere gradually changed with time from a normal-polarity
configuration to an inverse-polarity one. (4) The horizontal magnetic
field region was blueshifted. These indicate that helical flux rope
was emerging from below the photosphere into the corona along the PIL
under the preexisting prominence. We suggest that this supply of a
helical magnetic flux to the corona is associated with evolution and
maintenance of active region prominences.
Title: The Horizontal Magnetic Flux of the Quiet-Sun Internetwork
as Observed with the Hinode Spectro-Polarimeter
Authors: Lites, B. W.; Kubo, M.; Socas-Navarro, H.; Berger, T.; Frank,
Z.; Shine, R.; Tarbell, T.; Title, A.; Ichimoto, K.; Katsukawa, Y.;
Tsuneta, S.; Suematsu, Y.; Shimizu, T.; Nagata, S.
Bibcode: 2008ApJ...672.1237L
Altcode:
Observations of very quiet Sun using the Solar Optical
Telescope/Spectro-Polarimeter (SOT/SP) aboard the Hinode spacecraft
reveal that the quiet internetwork regions are pervaded by horizontal
magnetic flux. The spatial average horizontal apparent flux density
derived from wavelength-integrated measures of Zeeman-induced linear
polarization is BTapp = 55 Mx cm -2, as
compared to the corresponding average vertical apparent flux density of
| BLapp| = 11 Mx cm -2. Distributions
of apparent flux density are presented. Magnetic fields are organized on
mesogranular scales, with both horizontal and vertical fields showing
"voids" of reduced flux density of a few granules spatial extent. The
vertical fields are concentrated in the intergranular lanes, whereas the
stronger horizontal fields are somewhat separated spatially from the
vertical fields and occur most commonly at the edges of the bright
granules. High-S/N observations from disk center to the limb help
to constrain possible causes of the apparent imbalance between |
BLapp| and BTapp, with
unresolved structures of linear dimension on the surface smaller by at
least a factor of 2 relative to the SOT/SP angular resolution being one
likely cause of this discrepancy. Other scenarios for explaining this
imbalance are discussed. The horizontal fields are likely the source of
the "seething" fields of the quiet Sun discovered by Harvey et al. The
horizontal fields may also contribute to the "hidden" turbulent flux
suggested by studies involving Hanle effect depolarization of scattered
radiation.
Title: Hinode Observations of Flux Emergence in Quiet and Active
Regions
Authors: Lites, B. W.; Centeno, R.; Kubo, M.; Socas-Navarro, H. Berger,
T.; Frank, Z.; Shine, R.; Tarbell, T.; Title, A.; Ichimoto, K.;
Katsukawa, Y.; Tsuneta, S.; Suematsu, Y.; Shimizu, T.; Nagata, S.
Bibcode: 2008ASPC..383...71L
Altcode:
We review briefly the observational understanding of emergence of
flux in both the quiet Sun and active regions in the light of first
results from the joint Japan/US/UK Hinode mission. That spacecraft
is now providing us with our first continuous, high resolution
measurements of the photospheric vector magnetic field, along with
high resolution observations of the thermal and dynamic properties
of the chromosphere and corona. This review is intended to present a
few very early results and to highlight the potential for discovery
offered by this extraordinary new mission. The discovery of ubiquitous
horizontal magnetic flux in the quiet internetwork regions is presented.
Title: Mangetic field properties at the footpoints of solar
microflares (active-region transient brightenings)
Authors: Shimizu, T.; Kano, R.; Katsukawa, Y.; Kubo, M.; Deluca, E.;
Ichimoto, K.; Lites, B.; Nagata, S.; Sakao, T.; Shine, R.; Suematsu,
Y.; Tarbell, T.; Title, A.; Tsuneta, S.
Bibcode: 2007AGUFMSH52C..06S
Altcode:
Solar active regions produce numerous numbers of small-scale explosive
energy releases, i.e., microflares, which are captured by imaging
observations in soft X-rays as transient brightenings of small-scale
coronal loops. Thanks to advanced performance of X-Ray Telescope (XRT)
onboard the Hinode satellite, we can investigate finer structure
of the brightening X-ray sources in more details than we did with
Yohkoh data. One of important questions on microflares is what causes
microflares. The simultaneous visible-light observations by the Solar
Optical Telescope (SOT) allow us to explore magnetic activities
and magnetic field configuration at the photospheric footpoints
of brightening loops, giving key observations to investigate the
question. For our investigations of corona-photosphere magnetic
coupling, we have established co-alignment between SOT and XRT
with accuracy better than 1 arcsec (Shimizu et al. 2007, PASJ in
press). It turns out that Ca II H observations are very useful
to identify the exact positions of footpoints of X-ray transient
brightening loops. Small "Kernels" are sometimes observed in Ca II H
and they may be signature of highly accelerated non-thermal particles
impinging on chromosphere. As already shown in Shimizu et al.(2002),
frequent transient brightenings are observed at the locations where
emerging activities are on going. However, another type of brightening
triggering mechanism should exist to explain some observed multiple-loop
brightenings. In the multiple-loop brightenings, multiple loops are
magnetically in parallel with each other and no apparent magnetic
activities, such as emerging and canceling, are observed at and near
the footpoints. This paper will present SOT observations of some
microflares observed with XRT.
Title: Small-Scale Jetlike Features in Penumbral Chromospheres
Authors: Katsukawa, Y.; Berger, T. E.; Ichimoto, K.; Lites, B. W.;
Nagata, S.; Shimizu, T.; Shine, R. A.; Suematsu, Y.; Tarbell, T. D.;
Title, A. M.; Tsuneta, S.
Bibcode: 2007Sci...318.1594K
Altcode:
We observed fine-scale jetlike features, referred to as penumbral
microjets, in chromospheres of sunspot penumbrae. The microjets
were identified in image sequences of a sunspot taken through a Ca II
H-line filter on the Solar Optical Telescope on board the Japanese solar
physics satellite Hinode. The microjets’ small width of 400 kilometers
and short duration of less than 1 minute make them difficult to identify
in existing observations. The microjets are possibly caused by magnetic
reconnection in the complex magnetic configuration in penumbrae and
have the potential to heat the corona above a sunspot.
Title: Chromospheric Alfvénic Waves Strong Enough to Power the
Solar Wind
Authors: De Pontieu, B.; McIntosh, S. W.; Carlsson, M.; Hansteen,
V. H.; Tarbell, T. D.; Schrijver, C. J.; Title, A. M.; Shine, R. A.;
Tsuneta, S.; Katsukawa, Y.; Ichimoto, K.; Suematsu, Y.; Shimizu, T.;
Nagata, S.
Bibcode: 2007Sci...318.1574D
Altcode:
Alfvén waves have been invoked as a possible mechanism for the heating
of the Sun's outer atmosphere, or corona, to millions of degrees and
for the acceleration of the solar wind to hundreds of kilometers per
second. However, Alfvén waves of sufficient strength have not been
unambiguously observed in the solar atmosphere. We used images of
high temporal and spatial resolution obtained with the Solar Optical
Telescope onboard the Japanese Hinode satellite to reveal that the
chromosphere, the region sandwiched between the solar surface and
the corona, is permeated by Alfvén waves with strong amplitudes on
the order of 10 to 25 kilometers per second and periods of 100 to
500 seconds. Estimates of the energy flux carried by these waves and
comparisons with advanced radiative magnetohydrodynamic simulations
indicate that such Alfvén waves are energetic enough to accelerate
the solar wind and possibly to heat the quiet corona.
Title: Magnetic and Doppler Observations of the Photosphere and Low
Chromosphere with the Solar Optical Telescope on Hinode
Authors: Tarbell, T. D.; Lites, B. W.; Shine, R. A.; Ichimoto, K.
Bibcode: 2007AGUFMSH53A1064T
Altcode:
We present magnetic field and Doppler shift measurements in the Mg
I b line at 517.3 nm obtained with the Solar Optical Telescope's
Narrowband Filter Imager on Hinode. The line core forms in the low
chromosphere, and the wings where the measurements are made probably
form around the temperature minimum. Stokes IQUV images in the red and
blue wings are combined to make movies of longitudinal magnetograms
and Dopplergrams. The direction of the transverse field component is
also measurable in strong field concentrations. These are compared
with very accurate photospheric magnetic measurements in Fe I 630.2 nm
from the Spectro-Polarimeter. This comparison calibrates the filter
longitudinal magnetograms in flux density and shows changes in field
geometry with height. The Doppler measurements are calibrated using
wavelength scans through the Mg line profile. A number of emerging and
canceling magnetic features were observed in AR 10961 during its disk
passage in late June and early July. Since these were made during the
Hinode eclipse season, the observations have somewhat lower spatial
resolution than usual (0.32 arcsecond pixels), but the uniformity
and sensitivity are excellent. Intermittent upflows seen between
canceling magnetic features are interpreted in terms of reconnection
outflows. Strong, persistent downflows are seen adjacent to but not
on flux concentrations outside of sunspots and pores. In the sunspot,
running penumbral waves are clearly visible, and steady downflows are
observed over the light bridges. Hinode is a Japanese mission developed
and launched by ISAS/ JAXA, with NAOJ as domestic partner and NASA and
STFC (UK) as international partners. It is operated by these agencies
in cooperation with ESA and NSC (Norway).
Title: Chromospheric Anemone Jets as Evidence of Ubiquitous
Reconnection
Authors: Shibata, Kazunari; Nakamura, Tahei; Matsumoto, Takuma; Otsuji,
Kenichi; Okamoto, Takenori J.; Nishizuka, Naoto; Kawate, Tomoko;
Watanabe, Hiroko; Nagata, Shin'ichi; UeNo, Satoru; Kitai, Reizaburo;
Nozawa, Satoshi; Tsuneta, Saku; Suematsu, Yoshinori; Ichimoto, Kiyoshi;
Shimizu, Toshifumi; Katsukawa, Yukio; Tarbell, Theodore D.; Berger,
Thomas E.; Lites, Bruce W.; Shine, Richard A.; Title, Alan M.
Bibcode: 2007Sci...318.1591S
Altcode: 2008arXiv0810.3974S
The heating of the solar chromosphere and corona is a long-standing
puzzle in solar physics. Hinode observations show the ubiquitous
presence of chromospheric anemone jets outside sunspots in active
regions. They are typically 3 to 7 arc seconds = 2000 to 5000 kilometers
long and 0.2 to 0.4 arc second = 150 to 300 kilometers wide, and their
velocity is 10 to 20 kilometers per second. These small jets have an
inverted Y-shape, similar to the shape of x-ray anemone jets in the
corona. These features imply that magnetic reconnection similar to that
in the corona is occurring at a much smaller spatial scale throughout
the chromosphere and suggest that the heating of the solar chromosphere
and corona may be related to small-scale ubiquitous reconnection.
Title: Twisting Motions of Sunspot Penumbral Filaments
Authors: Ichimoto, K.; Suematsu, Y.; Tsuneta, S.; Katsukawa, Y.;
Shimizu, T.; Shine, R. A.; Tarbell, T. D.; Title, A. M.; Lites, B. W.;
Kubo, M.; Nagata, S.
Bibcode: 2007Sci...318.1597I
Altcode:
The penumbra of a sunspot is composed of numerous thin, radially
extended, bright and dark filaments carrying outward gas flows
(the Evershed flow). Using high-resolution images obtained by the
Solar Optical Telescope aboard the solar physics satellite Hinode, we
discovered a number of penumbral bright filaments revealing twisting
motions about their axes. These twisting motions are observed only
in penumbrae located in the direction perpendicular to the symmetry
line connecting the sunspot center and the solar disk center, and
the direction of the twist (that is, lateral motions of intensity
fluctuation across filaments) is always from limb side to disk-center
side. Thus, the twisting feature is not an actual twist or turn of
filaments but a manifestation of dynamics of penumbral filaments with
three-dimensional radiative transfer effects.
Title: Hinode SOT observations of plume upflows and cascading
downflows in quiescent solar prominences
Authors: Berger, T.; Shine, R.; Slater, G.; Tarbell, T.; Title, A.;
Lites, B.; Tsuneta, S.; Okamoto, T. J.; Ichimoto, K.; Katsukawa, Y.;
Sekii, T.; Suematsu, Y.; Shimizu, T.
Bibcode: 2007AGUFMSH53A1065B
Altcode:
We present several Hinode SOT filtergram movies of quiescent solar
prominences that show newly discovered "plume-like" upflows and
cascading "waterfall-like" downflows that persist for the entire
multi-hour duration of the observations. The flow speeds are on the
order of 10 km/sec with typical widths of 400-700 km. Preliminary
calculations show that if the upflows are buoyancy driven, the
associated thermal perturbation is on the order of 10,000 K, sufficient
to explain the dark appearance of the upflows in the interference
filter passbands. In addition we observe rotational vortices and
body oscillations within the prominences. These new observations
challenge current magnetostatic models of solar prominences by showing
that prominence plasmas are in constant motion, often in directions
perpendicular to the magnetic field lines proposed by the models. TRACE,
Hinode/EIS, and Hinode/XRT observations are used to investigate the
differential topology of the flows across temperature regimes.
Title: Coronal Transverse Magnetohydrodynamic Waves in a Solar
Prominence
Authors: Okamoto, T. J.; Tsuneta, S.; Berger, T. E.; Ichimoto, K.;
Katsukawa, Y.; Lites, B. W.; Nagata, S.; Shibata, K.; Shimizu, T.;
Shine, R. A.; Suematsu, Y.; Tarbell, T. D.; Title, A. M.
Bibcode: 2007Sci...318.1577O
Altcode: 2008arXiv0801.1958O
Solar prominences are cool 104 kelvin plasma clouds
supported in the surrounding 106 kelvin coronal plasma by
as-yet-undetermined mechanisms. Observations from Hinode show fine-scale
threadlike structures oscillating in the plane of the sky with periods
of several minutes. We suggest that these represent Alfvén waves
propagating on coronal magnetic field lines and that these may play
a role in heating the corona.
Title: Quiet-Sun Internetwork Magnetic Fields from the Inversion of
Hinode Measurements
Authors: Orozco Suárez, D.; Bellot Rubio, L. R.; del Toro Iniesta,
J. C.; Tsuneta, S.; Lites, B. W.; Ichimoto, K.; Katsukawa, Y.; Nagata,
S.; Shimizu, T.; Shine, R. A.; Suematsu, Y.; Tarbell, T. D.; Title,
A. M.
Bibcode: 2007ApJ...670L..61O
Altcode: 2007arXiv0710.1405O
We analyze Fe I 630 nm observations of the quiet Sun at disk center
taken with the spectropolarimeter of the Solar Optical Telescope aboard
the Hinode satellite. A significant fraction of the scanned area,
including granules, turns out to be covered by magnetic fields. We
derive field strength and inclination probability density functions from
a Milne-Eddington inversion of the observed Stokes profiles. They show
that the internetwork consists of very inclined, hG fields. As expected,
network areas exhibit a predominance of kG field concentrations. The
high spatial resolution of Hinode's spectropolarimetric measurements
brings to an agreement the results obtained from the analysis of
visible and near-infrared lines.
Title: Center-to-Limb Variation of Stokes V Asymmetries in Solar
Pores Observed with the Hinode Spectro-Polarimeter
Authors: Morinaga, Shuji; Nagata, Shin'ichi; Ichimoto, Kiyoshi;
Suematsu, Yoshinori; Tsuneta, Saku; Katsukawa, Yukio; Shimizu,
Toshifumi; Shine, Richard A.; Tarbell, Theodore D.; Title, Alan M.;
Lites, Bruce; Kubo, Masahito; Sakurai, Takashi
Bibcode: 2007PASJ...59S.613M
Altcode:
Here we present spectro-polarimetric measurements of several pores
and the surrounding regions taken with the Solar Optical Telescope
aboard Hinode at various viewing angles. We analyzed the Stokes V
area asymmetry, and confirmed that it is depressed at the center of
the pores, while it shows large positive values (a blue lobe larger
than a red lobe) in the surrounding area; this is consistent with a
previous report. In addition to this ring of positive asymmetry, we
found regions of alternating positive and negative area asymmetries
when weak V regions were observed near the solar limb. The positive
asymmetry occurs on the disk-center side and the negative asymmetry
on the limb side of the magnetic concentrations. These center-to-limb
variations of the Stokes V area asymmetry can be interpreted as being
a systematic inflow of plasma into the magnetic concentrations from
their surroundings.
Title: Initial Results on Line-of-Sight Field Calibrations of SP/NFI
Data Taken by SOT/Hinode
Authors: Chae, Jongchul; Moon, Yong-Jae; Park, Young-Deuk; Ichimoto,
Kiyoshi; Sakurai, Takashi; Suematsu, Yoshinori; Tsuneta, Saku;
Katsukawa, Yukio; Shimizu, Toshifumi; Shine, Richard A.; Tarbell,
Theodore D.; Title, Alan M.; Lites, Bruce; Kubo, Masahito; Nagata,
Shin'ichi; Yokoyama, Takaaki
Bibcode: 2007PASJ...59S.619C
Altcode:
We present initial results on the line-of-sight field calibration
of the two kinds of Stokes I and V data taken by the Solar Optical
Telescope on the satellite Hinode: spectral profiles of Stokes I and V
parameters recorded on the Spectro-polarimeter (SP), and monochromatic
images of the same parameters recorded on the Narrow-band Filter Imager
(NFI). By applying the center-of-gravity method to the SP data of
AR10930 taken on 2006 December 11, we determined the line-of-sight field
at every location in the active region. As a result, we found that the
line-of-sight field strength ranges up to 2kG in plages, even without
taking into account the filling factor, and up to 3.5kG or higher values
inside the umbra of the major sunspot. We calibrated the NFI data in
reference to the field determined from the SP data. In regions outside
the sunspots and the penumbral regions, we adopted a linear relation,
B|| = βV / I, between the circular polarization, V / I,
and the line-of-sight field strength, B||, and obtained β =
23.5kG in regions outside the sunspots, and β = 12.0kG in penumbral
regions. In umbral regions of sunspots, a first-order polynomial was
adopted to model the reversal of the polarization signal over the
field strength.
Title: Response of the Solar Atmosphere to Magnetic Flux Emergence
from Hinode Observations
Authors: Li, Hui; Sakurai, Takashi; Ichimito, Kiyoshi; Suematsu,
Yoshinori; Tsuneta, Saku; Katsukawa, Yukio; Shimizu, Toshifumi; Shine,
Richard A.; Tarbell, Theodore D.; Title, Alan M.; Lites, Bruce; Kubo,
Masahito; Nagata, Shin'ichi; Kotoku, Jun; Shibasaki, Kiyoto; Saar,
Steven H.; Bobra, Monica
Bibcode: 2007PASJ...59S.643L
Altcode:
No abstract at ADS
Title: Initial Helioseismic Observations by Hinode/SOT
Authors: Sekii, Takashi; Kosovichev, Alexander G.; Zhao, Junwei;
Tsuneta, Saku; Shibahashi, Hiromoto; Berger, Thomas E.; Ichimoto,
Kiyoshi; Katsukawa, Yukio; Lites, Bruce; Nagata, Shin'ichi; Shimizu,
Toshifumi; Shine, Richard A.; Suematsu, Yoshinori; Tarbell, Theodore
D.; Title, Alan M.
Bibcode: 2007PASJ...59S.637S
Altcode: 2007arXiv0709.1806S
Results from initial helioseismic observations by the Solar Optical
Telescope on-board Hinode are reported. It has been demonstrated
that intensity oscillation data from the Broadband Filter Imager
can be used for various helioseismic analyses. The k - ω power
spectra, as well as the corresponding time-distance cross-correlation
function, which promise high-resolution time-distance analysis below
the 6-Mm travelling distance, were obtained for G-band and CaII-H
data. Subsurface supergranular patterns were observed from our first
time-distance analysis. The results show that the solar oscillation
spectrum is extended to much higher frequencies and wavenumbers, and
the time-distance diagram is extended to much shorter travel distances
and times than were observed before, thus revealing great potential
for high-resolution helioseismic observations from Hinode.
Title: Hinode Observations of Horizontal Quiet Sun Magnetic Flux
and the ``Hidden Turbulent Magnetic Flux''
Authors: Lites, Bruce; Socas-Navarro, Hector; Kubo, Masahito; Berger,
Thomas; Frank, Zoe; Shine, Richard A.; Tarbell, Theodore D.; Title,
Alan M.; Ichimoto, Kiyoshi; Katsukawa, Yukio; Tsuneta, Saku; Suematsu,
Yoshinori; Shimizu, Toshifumi
Bibcode: 2007PASJ...59S.571L
Altcode:
We present observations of magnetic fields of the very quiet Sun
near disk center using the Spectro-Polarimeter of the Solar Optical
Telescope aboard the Hinode satellite. These observations reveal for
the first time the ubiquitous presence of horizontal magnetic fields in
the internetwork regions. The horizontal fields are spatially distinct
from the vertical fields, demonstrating that they are not arising mainly
from buffeting of vertical flux tubes by the granular convection. The
horizontal component has an average ``apparent flux density'' of
55Mxcm-2 (assuming the horizontal field structures are
spatially resolved), in contrast to the average apparent vertical flux
density of 11Mxcm-2. The vertical fields reside mainly in
the intergranular lanes, whereas the horizontal fields occur mainly
over the bright granules, with a preference to be near the outside
edge of the bright granules. The large apparent imbalance of vertical
and horizontal flux densities is discussed, and several scenarios are
presented to explain this imbalance.
Title: Strategy for the Inversion of Hinode Spectropolarimetric
Measurements in the Quiet Sun
Authors: Orozco Suárez, David; Bellot Rubio, Luis R.; Del Toro
Iniesta, Jose Carlos; Tsuneta, Saku; Lites, Bruce; Ichimoto, Kiyoshi;
Katsukawa, Yukio; Nagata, Shin'ichi; Shimizu, Toshifumi; Shine,
Richard A.; Suematsu, Yoshinori; Tarbell, Theodore D.; Title, Alan M.
Bibcode: 2007PASJ...59S.837O
Altcode: 2007arXiv0709.2033O
In this paper we propose an inversion strategy for the analysis of
spectropolarimetric measurements taken by Hinode in the quiet Sun. The
Spectro-Polarimeter of the Solar Optical Telescope aboard Hinode records
the Stokes spectra of the FeI line pair at 630.2nm with unprecendented
angular resolution, high spectral resolution, and high sensitivity. We
discuss the need to consider a local stray-light contamination to
account for the effects of telescope diffraction. The strategy is
applied to observations of a wide quiet Sun area at disk center. Using
these data we examine the influence of noise and initial guess models
in the inversion results. Our analysis yields the distributions of
magnetic field strengths and stray-light factors. They show that quiet
Sun internetwork regions consist mainly of hG fields with stray-light
contamination of about 0.8.
Title: Hinode Calibration for Precise Image Co-Alignment between
SOT and XRT (2006 November-2007 April)
Authors: Shimizu, Toshifumi; Katsukawa, Yukio; Matsuzaki, Keiichi;
Ichimoto, Kiyoshi; Kano, Ryohei; Deluca, Edward E.; Lundquist,
Loraine L.; Weber, Mark; Tarbell, Theodore D.; Shine, Richard A.;
Sôma, Mitsuru; Tsuneta, Saku; Sakao, Taro; Minesugi, Kenji
Bibcode: 2007PASJ...59S.845S
Altcode: 2007arXiv0709.4098S
To understand the physical mechanisms for activity and heating in
the solar atmosphere, the magnetic coupling from the photosphere
to the corona is an important piece of information from the Hinode
observations, and therefore precise positional alignment is required
among the data acquired by different telescopes. The Hinode spacecraft
and its onboard telescopes were developed to allow us to investigate
magnetic coupling with co-alignment accuracy better than 1". Using
the Mercury transit observed on 2006 November 8 and co-alignment
measurements regularly performed on a weekly basis, we have determined
the information necessary for precise image co-alignment, and have
confirmed that co-alignment better than 1" can be realized between
Solar Optical Telescope (SOT) and X-Ray Telescope (XRT) with our
baseline co-alignment method. This paper presents results from the
calibration for precise co-alignment of CCD images from SOT and XRT.
Title: Hinode Observations of a Vector Magnetic Field Change
Associated with a Flare on 2006 December 13
Authors: Kubo, Masahito; Yokoyama, Takaaki; Katsukawa, Yukio; Lites,
Bruce; Tsuneta, Saku; Suematsu, Yoshinori; Ichimoto, Kiyoshi; Shimizu,
Toshifumi; Nagata, Shin'ichi; Tarbell, Theodore D.; Shine, Richard A.;
Title, Alan M.; Elmore David
Bibcode: 2007PASJ...59S.779K
Altcode: 2007arXiv0709.2397K
Continuous observations of the flare productive active region 10930
were successfully carried out with the Solar Optical Telescope aboard
the Hinode spacecraft during 2006 December 6 to 19. We focused on the
evolution of photospheric magnetic fields in this active region, and the
magnetic field properties at the site of the X3.4 class flare, using
a time series of vector field maps with high spatial resolution. The
X3.4 class flare occurred on 2006 December 13 at the apparent
collision site between the large, opposite polarity umbrae. Elongated
magnetic structures with alternatingly positive and negative polarities
resulting from flux emergence appeared one day before the flare in the
collision site penumbra. Subsequently, the polarity inversion line
at the collision site became very complicated. The number of bright
loops in CaII H increased during the formation of these elongated
magnetic structures. Flare ribbons and bright loops evolved along
the polarity inversion line and one footpoint of the bright loop was
located in a region having a large departure of the field azimuth angle
with respect to its surroundings. SOT observations with high spatial
resolution and high polarization precision revealed temporal change in
the fine structure of magnetic fields at the flare site: some parts of
the complicated polarity inversion line then disappeared, and in those
regions the azimuth angle of the photospheric magnetic field changed by
about 90°, becoming more spatially uniform within the collision site.
Title: Fine-Scale Structures of the Evershed Effect Observed by the
Solar Optical Telescope aboard Hinode
Authors: Ichimoto, Kiyoshi; Shine, Richard A.; Lites, Bruce; Kubo,
Masahito; Shimizu, Toshifumi; Suematsu, Yoshinori; Tsuneta, Saku;
Katsukawa, Yukio; Tarbell, Theodore D.; Title, Alan M.; Nagata,
Shin'ichi; Yokoyama, Takaaki; Shimojo, Masumi
Bibcode: 2007PASJ...59S.593I
Altcode:
The small-scale structure of the Evershed effect is being studied
using data obtained by the Spectropolarimeter and the Broadband Filter
Imager of the Solar Optical Telescope aboard Hinode. We find that the
Evershed flow starts at the leading edge of inwardly migrating bright
penumbral grains, and turns to nearly a horizontal flow preferentially
in the dark lanes of the penumbra. A number of small elongated regions
that have an upward motion of ∼ 1kms-1 are found in the
deep photosphere distributed over the penumbra. They are cospatial
with bright grains and have relatively horizontal magnetic fields. A
number of patches having a strong downward motion associated with the
opposite magnetic polarity from the sunspot are also found in the mid
and outer penumbra. They could be identified as foot points of the
Evershed flow channels, though the identification of individual pairs
is not straightforward. Our results provide strong support for some
recent findings from ground-based high-resolution observations, and
are in general agreement with the well-known picture of the uncombed
structure of the penumbra, in which the penumbrae consist of rising
flux tubes carrying nearly horizontal Evershed flows embedded in more
vertical background magnetic fields.
Title: Flare Ribbons Observed with G-band and FeI 6302Å, Filters
of the Solar Optical Telescope on Board Hinode
Authors: Isobe, Hiroaki; Kubo, Masahito; Minoshima, Takashi; Ichimoto,
Kiyoshi; Katsukawa, Yukio; Tarbell, Theodore D.; Tsuneta, Saku; Berger,
Thomas E.; Lites, Bruce; Nagata, Shin'ichi; Shimizu, Toshifumi; Shine,
Richard A.; Suematsu, Yoshinori; Title, Alan M.
Bibcode: 2007PASJ...59S.807I
Altcode: 2007arXiv0711.3946I
The Solar Optical Telescope (SOT) on board the Hinode satellite observed
an X3.4 class flare on 2006 December 13. A typical two-ribbon structure
was observed, not only in the chromospheric CaII H line, but also in
the G-band and FeI 6302Å line. The high-resolution, seeing-free images
achieved by SOT revealed, for the first time, sub-arcsec fine structures
of the ``white light'' flare. The G-band flare ribbons on sunspot
umbrae showed a sharp leading edge, followed by a diffuse inside,
as well as a previously known core-halo structure. The underlying
structures, such as umbral dots, penumbral filaments, and granules,
were visible in the flare ribbons. Assuming that the sharp leading
edge was directly heated by a particle beam and the diffuse parts were
heated by radiative back-warming, we estimated the depth of the diffuse
flare emission using an intensity profile of the flare ribbon. We found
that the depth of the diffuse emission was about 100km or less from
the height of the source of radiative back-warming. The flare ribbons
were also visible in the Stokes-V images of FeI 6302Å, as a transient
polarity reversal. This is probably related to a ``magnetic transient''
reported in the literature. The intensity increase in Stokes-I images
indicates that the FeI 6302Å line was significantly deformed by the
flare, which may cause such a magnetic transient.
Title: Small-Scale Magnetic-Flux Emergence Observed with Hinode
Solar Optical Telescope
Authors: Otsuji, Kenichi; Shibata, Kazunari; Kitai, Reizaburo; Ueno,
Satoru; Nagata, Shin'ichi; Matsumoto, Takuma; Nakamura, Tahei;
Watanabe, Hiroko; Tsuneta, Saku; Suematsu, Yoshinori; Ichimoto,
Kiyoshi; Shimizu, Toshifumi; Katsukawa, Yukio; Tarbell, Theodore D.;
Lites, Bruce; Shine, Richard A.; Title Alan M.
Bibcode: 2007PASJ...59S.649O
Altcode: 2007arXiv0709.3207O
We observed small-scale magnetic-flux emergence in a sunspot moat region
by the Solar Optical Telescope (SOT) aboard the Hinode satellite. We
analyzed filtergram images observed at wavelengths of Fe 6302Å, G band,
and CaII H. In Stokes I images of Fe 6302Å, emerging magnetic flux was
recognized as dark lanes. In the G band, they showed to be their shapes
almost the same as in Stokes I images. These magnetic fluxes appeared
as dark filaments in CaII H images. Stokes V images of Fe 6302Å showed
pairs of opposite polarities at footpoints of each filament. These
magnetic concentrations were identified to correspond to bright points
in G band/CaII H images. From an analysis of time-sliced diagrams, we
derived the following properties of emerging flux, which are consistent
with those of previous studies: (1) Two footpoints separate each other
at a speed of 4.2kms-1 during the initial phase of evolution,
and decrease to about 1kms-1 10minutes later. (2) CaII H
filaments appear almost simultaneously with the formation of dark lanes
in Stokes I in an observational cadence of 2minutes. (3) The lifetime
of the dark lanes in the Stokes I and G band is 8minutes, while that
of Ca filament is 12minutes. An interesting phenomena was observed,
that an emerging flux tube expanded laterally in the photosphere with a
speed of 3.8kms-1. A discussion on the horizontal expansion
of the flux tube is given with refernce to previous simulation studies.
Title: Observations of Sunspot Oscillations in G Band and CaII H
Line with Solar Optical Telescope on Hinode
Authors: Nagashima, Kaori; Sekii, Takashi; Kosovichev, Alexander G.;
Shibahashi, Hiromoto; Tsuneta, Saku; Ichimoto, Kiyoshi; Katsukawa,
Yukio; Lites, Bruce; Nagata, Shin'ichi; Shimizu, Toshifumi; Shine,
Richard A.; Suematsu, Yoshinori; Tarbell, Theodore D.; Title, Alan M.
Bibcode: 2007PASJ...59S.631N
Altcode: 2007arXiv0709.0569N
Exploiting high-resolution observations made by the Solar Optical
Telescope on board Hinode, we investigate the spatial distribution
of the power spectral density of the oscillatory signal in and around
the active region NOAA 10935. The G-band data show that in the umbra
the oscillatory power is suppressed in all frequency ranges. On
the other hand, in CaII H intensity maps oscillations in the umbra,
so-called umbral flashes, are clearly seen with the power peaking around
5.5mHz. The CaII H power distribution shows the enhanced elements with
the spatial scale of the umbral flashes over most of the umbra, but
there is a region with suppressed power at the center of the umbra. The
origin and property of this node-like feature remain unexplained.
Title: Hinode SP Vector Magnetogram of AR10930 and Its
Cross-Comparison with MDI
Authors: Moon, Yong-Jae; Kim, Yeon-Han; Park, Young-Deuk; Ichimoto,
Kiyoshi; Sakurai, Takashi; Chae, Jongchul; Cho, Kyung Suk; Bong,
Suchan; Suematsu, Yoshinori; Tsuneta, Saku; Katsukawa, Yukio; Shimojo,
Masumi; Shimizu, Toshifumi; Shine, Richard A.; Tarbell, Theodore D.;
Title, Alan M.; Lites, Bruce; Kubo, Masahito; Nagata, Shin'ichi;
Yokoyama, Takaaki
Bibcode: 2007PASJ...59S.625M
Altcode:
We present one Hinode Spectropolarimeter (SP) magnetogram of AR 10930
that produced several major flares. The inversion from Stokes profiles
to magnetic field vectors was made using the standard Milne-Eddington
code. We successfully applied the Uniform Shear Method for resolving
the 180° ambiguity to the magnetogram. The inversion gave very strong
magnetic field strengths (near 4500 gauss) for a small portion of area
in the umbra. Considering that the observed V-profile of 6301.5Å was
well-fitted as well as a direct estimation of the Zeeman splitting
results in 4300-4600 gauss, we think that the field strengths
should not be far from the actual value. A cross-comparison of the
Hinode SP and SOHO MDI high resolution flux densities shows that the
MDI flux density could be significantly underestimated by about a
factor of two. In addition, it has a serious negative correlation
(the so-called Zeeman saturation effect) with the Hinode SP flux
density for umbral regions. Finally, we could successfully obtain
a recalibrated MDI magnetogram that has been corrected for the
Zeeman saturation effect using not only a pair of MDI intensity and
magnetogram data simultaneously observed, but also the relationship
from the cross-comparison between the Hinode SP and MDI flux densities.
Title: Formation Process of a Light Bridge Revealed with the Hinode
Solar Optical Telescope
Authors: Katsukawa, Yukio; Yokoyama, Takaaki; Berger, Thomas E.;
Ichimoto, Kiyoshi; Kubo, Masahito; Lites, Bruce; Nagata, Shin'ichi;
Shimizu, Toshifumi; Shine, Richard A.; Suematsu, Yoshinori; Tarbell,
Theodore D.; Title, Alan M.; Tsuneta, Saku
Bibcode: 2007PASJ...59S.577K
Altcode: 2007arXiv0709.2527K
The Solar Optical Telescope (SOT) on-board Hinode successfully and
continuously observed the formation process of a light bridge in a
matured sunspot of the NOAA active region 10923 for several days with
high spatial resolution. During its formation, many umbral dots were
observed to be emerging from the leading edges of penumbral filaments,
and rapidly intruding into the umbra. The precursor of the light bridge
formation was also identified as a relatively slow inward motion of
the umbral dots, which emerged not near the penumbra, but inside the
umbra. The spectro-polarimeter on SOT provided physical conditions in
the photosphere around the umbral dots and the light bridges. We found
that the light bridges and the umbral dots had significantly weaker
magnetic fields associated with upflows relative to the core of the
umbra, which implies that there was hot gas with weak field strength
penetrating from the subphotosphere to near the visible surface inside
those structures. There needs to be a mechanism to drive the inward
motion of the hot gas along the light bridges. We suggest that the
emergence and the inward motion are triggered by a buoyant penumbral
flux tube as well as subphotospheric flow crossing the sunspot.
Title: Umbral Fine Structures in Sunspots Observed with Hinode Solar
Optical Telescope
Authors: Kitai, Reizaburo; Watanabe, Hiroko; Nakamura, Tahei; Otsuji,
Ken-ichi; Matsumoto, Takuma; UeNo, Satoru; Nagata, Shin'ichi; Shibata,
Kazunari; Muller, Richard; Ichimoto, Kiyoshi; Tsuneta, Saku; Suematsu,
Yoshinori; Katsukawa, Yukio; Shimizu, Toshifumi; Tarbell, Theodore D.;
Shine, Richard A.; Title, Alan M.; Lites, Bruce
Bibcode: 2007PASJ...59S.585K
Altcode: 2007arXiv0711.3266K
A high resolution imaging observation of a sunspot umbra was made with
the Hinode Solar Optical Telescope. Filtergrams at wavelengths of the
blue and green continua were taken during three consecutive days. The
umbra consisted of a dark core region, several diffuse components,
and numerous umbral dots. We derived basic properties of umbral dots
(UDs), especially their temperatures, lifetimes, proper motions,
spatial distribution, and morphological evolution. The brightness
of UDs is confirmed to depend on the brightness of their surrounding
background. Several UDs show fission and fusion. Thanks to the stable
condition of the space observation, we could for the first time follow
the temporal behavior of these events. The derived properties of the
internal structure of the umbra are discussed from the viewpoint of
magnetoconvection in a strong magnetic field.
Title: Formation of Moving Magnetic Features and Penumbral Magnetic
Fields with Hinode/SOT
Authors: Kubo, Masahito; Ichimoto, Kiyoshi; Shimizu, Toshifumi;
Tsuneta, Saku; Suematsu, Yoshinori; Katsukawa, Yukio; Nagata,
Shin'ichi; Tarbell, Theodore D.; Shine, Richard A.; Title, Alan M.;
Frank, Zoe A.; Lites, Bruce; Elmore, David
Bibcode: 2007PASJ...59S.607K
Altcode: 2007arXiv0709.1853K
Vector magnetic fields of moving magnetic features (MMFs) were well
observed with the Solar Optical Telescope (SOT) aboard the Hinode
satellite. We focused on the evolution of three MMFs with the SOT in
this study. We found that an MMF having relatively vertical fields
with the same polarity as the sunspot was detached from the penumbra
around the granules appearing in the outer penumbra. This suggests
that granular motions in the outer penumbra are responsible for
disintegration of the sunspot. Two MMFs with polarity opposite to
the sunspot are located around the outer edge of horizontal fields
extending from the penumbra. This is evidence that the MMFs with
polarity opposite to the sunspot are the prolongation of penumbral
horizontal fields. Redshifts larger than the sonic velocity in the
photosphere are detected for some of the MMFs with polarity opposite
to the sunspot.
Title: A Tale of Two Spicules: The Impact of Spicules on the Magnetic
Chromosphere
Authors: de Pontieu, Bart; McIntosh, Scott; Hansteen, Viggo H.;
Carlsson, Mats; Schrijver, Carolus J.; Tarbell, Theodore D.; Title,
Alan M.; Shine, Richard A.; Suematsu, Yoshinori; Tsuneta, Saku;
Katsukawa, Yukio; Ichimoto, Kiyoshi; Shimizu, Toshifumi; Nagata,
Shin'ichi
Bibcode: 2007PASJ...59S.655D
Altcode: 2007arXiv0710.2934D
We use high-resolution observations of the Sun in CaIIH (3968Å)
from the Solar Optical Telescope on Hinode to show that there are
at least two types of spicules that dominate the structure of the
magnetic solar chromosphere. Both types are tied to the relentless
magnetoconvective driving in the photosphere, but have very different
dynamic properties. ``Type-I'' spicules are driven by shock waves
that form when global oscillations and convective flows leak into
the upper atmosphere along magnetic field lines on 3--7minute
timescales. ``Type-II'' spicules are much more dynamic: they form
rapidly (in ∼ 10s), are very thin (≤ 200 km wide), have lifetimes
of 10-150s (at any one height), and seem to be rapidly heated to
(at least) transition region temperatures, sending material through
the chromosphere at speeds of order 50--150kms-1. The
properties of Type II spicules suggest a formation process that is
a consequence of magnetic reconnection, typically in the vicinity
of magnetic flux concentrations in plage and network. Both types of
spicules are observed to carry Alfvén waves with significant amplitudes
of order 20kms-1.
Title: Hinode Observations of the Onset Stage of a Solar Filament
Eruption
Authors: Sterling, Alphonse C.; Moore, Ronald L.; Berger, Thomas
E.; Bobra, Monica; Davis, John M.; Jibben, Patricia; Kano, Ryohei;
Lundquist, Loraine L.; Myers, D.; Narukage, Noriyuki; Sakao, Taro;
Shibasaki, Kiyoto; Shine, Richard A.; Tarbell, Theodore D.; Weber, Mark
Bibcode: 2007PASJ...59S.823S
Altcode:
We used Hinode X-Ray Telescope (XRT) and Solar Optical Telescope (SOT)
filtergraph (FG) Stokes-V magnetogram observations, to study the
early onset of a solar eruption that includes an erupting filament
that we observe in TRACE EUV images. The filament undergoes a slow
rise for at least 20min prior to its fast eruption and strong soft
X-ray (SXR) flaring; such slow rises have been previously reported,
and the new Hinode data elucidate the physical processes occurring
during this period. XRT images show that during the slow-rise phase,
an SXR sigmoid forms from apparent reconnection low in the sheared core
field traced by the filament, and there is a low-level intensity peak
in both EUV and SXRs during the slow rise. MDI and SOT FG Stokes-V
magnetograms show that the pre-eruption filament is along a neutral
line between opposing-polarity enhanced network cells, and the SOT
magnetograms show that these opposing fields are flowing together
and canceling for at least six hours prior to eruption. From the MDI
data we measured the canceling network fields to be ∼ 40G, and we
estimated that ∼ 1019 Mx of flux canceled during the
five hours prior to eruption; this is only ∼ 5% of the total flux
spanned by the eruption and flare, but apparently its tether-cutting
cancellation was enough to destabilize the sigmoid field holding the
filament and resulted in that field's eruption.
Title: Performance Characteristics of the Solar-B Spectro-Polarimeter
Authors: Lites, B. W.; Elmore, D. F.; Streander, K. V.; Hoffmann,
C. M.; Tarbell, T. D.; Title, A. M.; Shine, R. A.; Ichimoto, K.;
Tsuneta, S.; Shimizu, T.; Suematsu, Y.
Bibcode: 2007ASPC..369...55L
Altcode:
The Focal Plane Package (FPP) of the Solar Optical Telescope (SOT)
includes the first precision Spectro-Polarimeter (SP) for solar space
observations. The FPP/SP will provide high precision measures of
the vector magnetic field in the solar photosphere. Here we present
some as-built performance specifications for the entire system of
telescope + polarimeter. The FPP-SP system represents significant
gains in several aspects over existing spectro-polarimetric systems;
notably, angular resolution, polarimetric accuracy, spectral purity,
and most importantly, temporal continuity of stable, high angular
resolution. In this short summary of the poster, a few of the
performance characteristics of the SP are presented.
Title: Calibration of the SOT Polarization
Authors: Ichimoto, K.; Suematsu, Y.; Shimizu, T.; Katsukawa, Y.;
Noguchi, M.; Nakagiri, M.; Miyashita, M.; Tsuneta, S.; Tarbell, T. D.;
Shine, R. A.; Hoffmann, C. M.; Cruz, T.; Lites, B. W.; Elmore, D. F.
Bibcode: 2007ASPC..369...39I
Altcode:
Calibration of SOT polarization property was performed using natural
sunlight and well calibrated sheet polarizer (linear and circular)
placed on the entrance of the telescope. The polarimeter response
matrices were determined for the spectropolarimeter (SP) and the
narrowband filter imager (NFI), and it is shown that they are well
behave as predicted and constant over the field of view. The crosstalk
between I,Q,U,V will be suppressed to the negligible level at the
photometric accuracy of 10^{-3} after the calibration with the obtained
matrices. The sensitivity of SOT on linear and circular polarizations
at each wavelength observed by NFI are also obtained.
Title: Calibration of SOT Dopplergrams
Authors: Katsukawa, Y.; Ichimoto, K.; Sekii, T.; Suematsu, Y.; Tsuneta,
S.; Shine, R. A.; Tarbell, T. D.
Bibcode: 2007ASPC..369...43K
Altcode:
Narrow-band Filter Imager on SOT provides Dopplergrams (DGs) which
are images of Doppler (line- of-sight) velocities. Observations with
DGs are critically important in studies of photospheric dynamics and
helioseismology. The primary photospheric line used for DGs is Fe I 5576
Å which is a line insensitive to Zeeman effect. We made a calibration
function for the 5576 Å DGs to get actual Doppler velocities from
velocity indexes using an atlas spectrum and simulated transmission
profiles for the tunable filter (TF) on SOT. Using data sets taken
in the natural sun-light test, we quantitatively evaluated accuracy
of the DGs by comparing the rotational speed of the Sun measured
with DGs with the expected one. There was a little systematic error
in the velocity obtained by SOT, but the error was less than 20 %
of the predicted velocities.
Title: Vector Spectropolarimetry of Dark-cored Penumbral Filaments
with Hinode
Authors: Bellot Rubio, L. R.; Tsuneta, S.; Ichimoto, K.; Katsukawa,
Y.; Lites, B. W.; Nagata, S.; Shimizu, T.; Shine, R. A.; Suematsu,
Y.; Tarbell, T. D.; Title, A. M.; del Toro Iniesta, J. C.
Bibcode: 2007ApJ...668L..91B
Altcode: 2007arXiv0708.2791B
We present spectropolarimetric measurements of dark-cored penumbral
filaments taken with Hinode at a resolution of 0.3". Our observations
demonstrate that dark-cored filaments are more prominent in polarized
light than in continuum intensity. Far from disk center, the Stokes
profiles emerging from these structures are very asymmetric and show
evidence for magnetic fields of different inclinations along the
line of sight, together with strong Evershed flows of at least 6-7 km
s-1. In sunspots closer to disk center, dark-cored penumbral
filaments exhibit regular Stokes profiles with little asymmetries due
to the vanishing line-of-sight component of the horizontal Evershed
flow. An inversion of the observed spectra indicates that the magnetic
field is weaker and more inclined in the dark cores as compared with
the surrounding bright structures. This is compatible with the idea
that dark-cored filaments are the manifestation of flux tubes carrying
hot Evershed flows.
Title: Emergence of Small-Scale Magnetic Loops in the Quiet-Sun
Internetwork
Authors: Centeno, R.; Socas-Navarro, H.; Lites, B.; Kubo, M.; Frank,
Z.; Shine, R.; Tarbell, T.; Title, A.; Ichimoto, K.; Tsuneta, S.;
Katsukawa, Y.; Suematsu, Y.; Shimizu, T.; Nagata, S.
Bibcode: 2007ApJ...666L.137C
Altcode: 2007arXiv0708.0844C
We study the emergence of magnetic flux at very small spatial
scales (less than 2") in the quiet-Sun internetwork. To this aim,
a time series of spectropolarimetric maps was taken at disk center
using the instrument SP/SOT on board Hinode. The LTE inversion of
the full Stokes vector measured in the Fe I 6301 and 6302 Å lines
allows us to retrieve the magnetic flux and topology in the region
of study. In the example presented here, the magnetic flux emerges
within a granular structure. The horizontal magnetic field appears
prior to any significant amount of vertical field. As time goes on,
the traces of the horizontal field disappear, while the vertical dipoles
drift-carried by the plasma motions-toward the surrounding intergranular
lanes. These events take place within typical granulation timescales.
Title: Chromospheric Micro-jets Discovered Above Sunspot Penumbrae
Authors: Katsukawa, Yukio; Tsuneta, S.; Suematsu, Y.; Ichimoto, K.;
Shimizu, T.; Kubo, M.; Nagata, S.; Berger, T.; Tarbell, T.; Shine,
R.; Title, A.
Bibcode: 2007AAS...210.9413K
Altcode: 2007BAAS...39..219K
The Solar Optical Telescope (SOT) aboard HINODE allows us to observe
dynamical activities in the solar photosphere and the chromosphere
with high and stable image quality of 0.2 arcseconds. This superior
performance of SOT provides new findings of fine-scale transient
activities occurring in the chromosphere. In this paper, we report
discovery of fine-scale jet-like phenomena ubiquitously observed
above sunspot penumbrae. The jets are identified in image sequences
of a sunspot taken through a Ca II H line filter at 3968A. The Ca II
H line is sensitive to about 10^4 K plasma in the chromosphere. Their length is typically between 3000 and 10000km, and their
width is smaller than 500km. It is notable that their lifetime
is shorter than 1 minute. Those small spatial and temporal scale
possibly makes it difficult to identify the phenomena in existing
ground-based observations. The jets are easily identified when a
sunspot is located far from the disk center, and motion of the bright
features suggests that mass is erupted from lower chromosphere to upper
atmosphere. Velocities of the motion are estimated to be 50 to 100 km/s
from their lateral motion of intensity patterns. The velocities are much
faster than sound speeds in the chromosphere. A possible cause of such
high-speed jets is magnetic reconnection at the lower chromosphere
resulted from fluted magnetic configuration in penumbrae which is
suggested by vector magnetic field measurements in the photosphere.
Title: Magnetic Patches in Internetwork Quiet Sun
Authors: De Wijn, Alfred; Lites, B.; Berger, T.; Shine, R.; Title,
A.; Katsukawa, Y.; Tsuneta, S.; Suematsu, Y.; Shimizu, T.; Hinode Team
Bibcode: 2007AAS...210.9412D
Altcode: 2007BAAS...39Q.219D
We study strong flux elements in the quiet sun in the context of
the nature of quiet-sun magnetism, its coupling to chromospheric,
transition-region and coronal fields, and the nature of a local
turbulent dynamo. Strong, kilogauss flux elements show up intermittently
as small bright points in G-band and Ca II H images. Although
bright points have been extensively studied in the magnetic network,
internetwork magnetism has only come under scrutiny in recent years. A
full spectrum of field strengths seems to be ubiquitously present in
the internetwork at small spatial scales, with the stronger elements
residing in intergranular lanes. De Wijn et al. (2005) found that bright
points in quiet sun internetwork areas appear recurrently with varying
intensity and horizontal motion within long-lived patches that outline
cell patterns on mesogranular scales. They estimate that the "magnetic
patches" have a mean lifetime of nine hours, much longer than granular
timescales. We use multi-hour sequences of G-band and Ca II H images
as well as magnetograms recorded by the Hinode satellite to follow up
on their results. The larger field of view, the longer sequences, the
addition of magnetograms, and the absence of atmospheric seeing allows
us to better constrain the patch lifetime, to provide much improved
statistics on IBP lifetime, to compare IBPs to network bright points,
and to study field polarity of IBPs in patches and between nearby
patches. Hinode is an international project supported by JAXA,
NASA, PPARC and ESA. We are grateful to the Hinode team for all their
efforts in the design, build and operation of the mission.
Title: High Resolution Observation of Spicules in Ca II H with
Hinode/SOT
Authors: Suematsu, Yoshinori; Katsukawa, Y.; Ichimoto, K.; Tsuneta, S.;
Okamoto, T.; Nagata, S.; Shimizu, T.; Tarbell, T.; Shine, R.; Title, A.
Bibcode: 2007AAS...210.9411S
Altcode: 2007BAAS...39..219S
High cadence observation with a Ca II H broadband filtergraph
(passband of 0.25 nm) of the Solar Optical Telescope (SOT) aboard
HINODE has revealed dynamical nature of solar limb spicules. Thanks to a
diffraction-limited and low-scattered light property of the instrument,
we can track the detailed evolution of individual spicules for the first
time with a spatial resolution of 0.2 arcsec. The spicules in Ca II
H are typically several arcsec tall and have multi-thread structure;
each threads are a few tenth of arcsec wide. It should be stressed
that most spicules do not show a simple up-and-down motion along a
rigid path line. They start with bright structure emanating from Ca II
H bright region, get widen and diffused with time and ascent, showing
expansion with lateral or even helical motion in tall events. Small and
short lived spicules tend to fade out after ascent. We will present
new findings of spicule dynamics in different magnetic environments
and discuss about long standing controversy of its motion and evolution.
Title: Hinode/SOT Observation of Fine Structure of the Evershed Flow
Authors: Ichimoto, Kiyoshi; Suematsu, Y.; Tsuneta, S.; Katsukawa, Y.;
Shimojo, M.; Kubo, M.; Shimizu, T.; Shine, R.; Tarbell, T.; Title,
A.; Lites, B.; Elmore, D.; Yokoyama, T.; Nagaka, S.
Bibcode: 2007AAS...210.9408I
Altcode: 2007BAAS...39..218I
Small scale structure of the Evershed effect was studied using the
Spectropolarimeter (SP) and Broadband Filter Imager (BFI) of SOT aboard
Hinode. SP maps and high cadence continuum images of BFI coverting
entire sunspots are used to investigate the spatial distribution of
the flow field, brightness and magnetic fields. It is revealed that the
Evershed flow starts at the front edge of inwardly migrating penumbral
grains with an upward velocity component and turns to nearly holizontal
flow preferentially in dark lanes (or dark core of filaments) of the
penumbra. Our results are in general agreement with the well known
uncombed penumbral concept in which the Evershed flow takes place
in nearly holizontal field channels. We discovered a number of tiny
elongated regions in deep photosphere in which there is an obvious
upward motion of 1-1.5km/s distributing over the penumbra. They
could be identified as the 'foot points' of the individual Evershed
flow channels. Cross-correlation among the flow speed, intensity,
magnetic field strength and inclination, and distribution of string
down flows in and around the penumbra will also be discussed.
Title: Magnetic Flux Emergence In The Quiet Sun Photosphere
Authors: Centeno, Rebecca; Lites, B.; Socas-Navarro, H.; Frank,
Z.; Shine, R.; Tarbell, T.; Title, A.; Ichimoto, K.; Tsuneta, S.;
Katsukawa, Y.; Suematsu, Y.; Kubo, M.; Shimizu, T.
Bibcode: 2007AAS...210.9406C
Altcode: 2007BAAS...39..218C
We study the emergence of magnetic flux at very small spacial scales
(less than 1 arcsec) in the quiet Sun internetwork. To this aim, several
time series of spectropolarimetric maps were taken at disk center using
the instrument SP/SOT on board Hinode. The LTE inversion of the full
Stokes vector measured in the Fe I 6301 and 6302 lines will allow us
to retrieve the magnetic flux and topology in the region of study. We
find that the magnetic flux emerges typically within the granular
structures. In many cases, the horizontal magnetic field appears
prior to any significant amount of vertical field. As time goes on,
the traces of the horizontal field dissapear while the the vertical
dipoles drift -carried by the plasma motions- towards the surrounding
intergranular lanes. Sometimes they stay trapped there for a while
but they eventually either disappear by disgregation/cancelation
or agregate to other magnetic field concentrations giving rise to
larger flux elements. The time scale of these events is of the order
of 10-20 minutes.
Title: Formation of Moving Magnetic Features and Penumbral Magnetic
Fields
Authors: Kubo, Masahito; Ichimoto, K.; Shimizu, T.; Tsuneta, S.;
Suematsu, Y.; Katsukawa, Y.; Nagata, S.; Lites, B. W.; Frank, Z.;
Tarbell, T. D.; Shine, R. A.; Title, A. M.
Bibcode: 2007AAS...210.9410K
Altcode: 2007BAAS...39..218K
We investigate the formation process of Moving Magnetic Features
(MMFs) observed with Hinode/SOT. Moving magnetic features are small
magnetic elements moving outward in the moat region surrounding
mature sunspots. We derive vector magnetic fields of MMFs around
simple sunspots near the disk center. Most of MMFs with polarity
opposite to the sunspot have large redshift around the penumbral outer
boundary. We find that some of them have Doppler velocities of about
10 km/s and such large Doppler motion is observed only in the Stokes
V profile. The Stokes Q and U profiles in the same pixel do not have
any significant Doppler motions. Horizontal magnetic fields of the
penumbra frequently extend to the moat region and the MMFs having
horizontal fields with polarity same as the sunspot are formed. The
MMFs with polarity opposite to the sunspot appear around the outer
edge of the extending penumbral fields. We also find penumbral spines,
which have more vertical magnetic fields than the surroundings, branch
off at their outer edge and MMFs having relatively vertical fields
with polarity same as the sunspot are detached from the outer edge
of the branch. The branch of penumbral spine is formed when granular
cells in the moat region go into the penumbra.
Title: Ubiquitous Horizontal Magnetic Fields in the Quiet Solar
Photosphere as Revealed by HINODE Meaurements
Authors: Lites, Bruce W.; Socas Navarro, H.; Berger, T.; Frank,
Z.; Shine, R.; Tarbell, T.; Title, A.; Ichimoto, K.; Katsukawa,
Y.; Tsuneta, S.; Suematsu, Y.; Kubo, M.; Shimizu, T.; Nagata, S.;
Hinode Team
Bibcode: 2007AAS...210.6303L
Altcode: 2007BAAS...39..171L
Measurements with the HINODE Spectro-Polarimeter (SP) of the quiet
Sun allow characterization of the weak, mixed-polarity magnetic
flux at the highest angular resolution to date (0.3"), and with good
polarimetric sensitivity(0.025% relative to the continuum). The image
stabilization of the HINODE spacecraft allows long integrations with
degradation of the image quality only by the evolution of the solar
granulation. From the Stokes V profile measurements we find an average
solar "Apparent Flux Density" of 14 Mx cm-2, with significant Stokes V
signals at every position on the disk at all times. However, there are
patches of meso-granular size (5-15") where the flux is very weak. At
this high sensitivity, transverse fields produce measurable Stokes
Q,U linear polarization signals over a majority of the area, with
apparent transverse flux densities in the internetwork significantly
larger than the corresponding longitudinal flux densities. When viewed
at the center of the solar disk, the Stokes V signals (longitudinal
fields) show a preference for occurrence in the intergranular lanes,
and the Q,U signals occur preferably over the granule interiors,
but neither association is exclusive. Hinode is an international
project supported by JAXA, NASA, PPARC and ESA. We are grateful to the
Hinode team for all their efforts in the design, build and operation
of the mission.
Title: Discovery Of Cool Cloud-like Structures In The Corona With
Hinode Solar Optical Telescope
Authors: Okamoto, Takenori; Tsuneta, S.; Katsukawa, Y.; Ichimoto,
K.; Suematsu, Y.; Shimizu, T.; Nagata, S.; Shibata, K.; Tarbell, T.;
Shine, R.; Berger, T.; Lites, B.; Myers, D.
Bibcode: 2007AAS...210.9426O
Altcode: 2007BAAS...39..221O
A solar observation satellite Hinode (Japanese for sun rise) was
launched in September 2006.Hinode carried 3 advanced solar telescopes,
visible light telescope, EUV imaging spectrometer, and X-ray telescope
to simultaneously observe the photosphere, chromosphere, transition
region, and corona. In the performance verification phase of the Hinode
spacecraft with its telescopes, we observed an active region AR10921
near the west limb of the solar disk on November 9 2006. At this point,
we planned to observe spicules on the limb with a broadband filter
dedicated to Ca II H line (3968A). Ca II-H emission line (3968A) comes
from plasma with temperature of approx. 10(4) K, which is much lower
than the coronal temperature of 10(6-7) K. In addition to spectacular
spicules, we find a large cloud-like structure located 10,000-20,000
km above the limb. The cloud has a very complex fine structure with
dominant horizontal thread-like structure. Some features are moving
horizontally and also have clear vertical oscillatory motions. The
periods and amplitudes of these oscillations are 130-250 seconds and
200-850 km, respectively. The vertical oscillatory motion sometimes
has a coherence length as long as 16,000 km. We conclude that from
various observational features this vertical oscillation is a signature
of Alfven waves propagating along the horizontal magnetic fields. We
will discuss their origin and implications.
Title: Hinode/SOT Observations of Sunspot Penumbral Dynamics and
Evolution
Authors: Shine, Richard A.; Hagenaar, M.; Tarbell, T.; Title, A.;
Lites, B.; Ichimoto, K.; Tsuneta, S.; Katsakawa, Y.; Suematsu, Y.;
Nagata, S.; Kubo, M.; Shimizu, T.
Bibcode: 2007AAS...210.9407S
Altcode: 2007BAAS...39..218S
The Solar Optical Telescope (SOT) on the Hinode satellite (launched
October 2006) has obtained long and nearly continuous time series of
several large sunspots including those in NOAA AR's 10923, 10925,
and 10930. Here we use high resolution movies taken primarily with
the broad band Ca II (396.8nm) and G band (430.5nm) channels and
magnetograms taken with the 630.2nm narrow band channel to study
the details and short term evolution of penumbral fine structures
as well as the long term evolution of the sunspots. We compute flow
maps and use space/time slices to track motions of Evershed clouds,
penumbral grains, and visualize oscillations. The data contain examples
of penumbral formation and disintegration including "orphan" penumbra
(i.e., penumbra without an obvious umbra). There is also an interesting
instance of "colliding" penumbra in AR 10930 as two sunspots of opposite
polarity converged. The zone of apparent shear was associated with
several flares. This work was supported by NASA contract NNM07AA01C
Title: Magnetic Field Diagnostic Capability of Solar-B/SOT:
Filtergraph Instrument
Authors: Ichimoto, K.; Suematsu, Y.; Shimizu, T.; Katsukawa, Y.;
Tsuneta, S.; Tarbell, T. D.; Shine, R. A.; Hoffmann, C. M.; Title,
A. M.; Lites, B. W.; Elmore, D. F.; Streander, K. V.
Bibcode: 2006ASPC..358..189I
Altcode:
The Narrowband Filter Instrument (NFI) of the Solar Optical Telescope
onboard Solar-B provides 2D magnetograms/Dopplergrams with a tunable
Lyot filter (width ∼ 0.1 Å) in 6 selected wavelength bands, and
spatial sampling of 0.08 arcsec/px. The Zeeman-effect sensitivity of
NFI and the detection limits of weak magnetic fields are evaluated for
2 photospheric and 3 chromospheric lines. Magnetic-field retrievability
from the NFI observables is studied using synthetic Stokes profiles
of Fe I 5250 Å. We find that, with optimized wavelength sampling at 4
positions, the inferred magnetic field is sufficiently accurate under
the hypothesis of constant magnetic field and velocity along the LOS.
Title: Moving Magnetic Features Observed Simultaneously With Trace
And DST
Authors: Hagenaar-Daggett, Hermance J.; Shine, R. A.
Bibcode: 2006SPD....37.0709H
Altcode: 2006BAAS...38..229H
In this paper, we study observations of sunspots made in June - July
2005, with TRACE 1600A and the Dunn Solar telescope at Sac Peak. In
that period MDI was in a continuous contact mode in which it makes only
FD magnetograms. The 1600A line, however, is highly correlated with
the unsigned magnetic flux density, and we use an automated algorithm
to detect moving magnetic features around sunspots. We compare our
findings with the ground based observations in the Gband, CaK line,
Halpha, and Stokes spectra.
Title: Coupling effects throughout the solar atmosphere: Emerging
magnetic flux and structure formation
Authors: Ryutova, M.; Shine, R.
Bibcode: 2006JGRA..111.3101R
Altcode: 2006JGRA..11103101R
We report observations of the "birth," formation, and evolution
of compact coronal structures associated with strong localized
motions generated by emerging magnetic flux in the photosphere. We
use multiwavelength time series of data taken simultaneously with the
Swedish Vacuum Solar Telescope (SVST) on La Palma, the TRACE satellite,
and the MDI instrument on SOHO. We find that long before the magnetic
pore is formed, the chromosphere and transition region show a high
activity above the future site of pore formation: rising but not yet
visible magnetic flux exerts a strong pressure on the overlying plasma
generating highly collimated plasma flows seen in the Hα images. About
the time when the magnetic pores are formed and the Hα surges bifurcate
into the established arc-like flows, a system of compact coronal loops
is formed, showing direct connection between the motions associated with
the evolving magnetic fields and the coronal structure formation. We
propose a mechanism that may lead to the observed phenomena based on
the generation of currents by strong disturbances propagating upward
from a limited surface area.
Title: Moving Magnetic Features around Sunspots
Authors: Hagenaar, Hermance J.; Shine, Richard A.
Bibcode: 2005ApJ...635..659H
Altcode:
We study statistical properties of small-scale magnetic features
around sunspots using time sequences of high-resolution magnetograms
of eight sunspots made with the Michelson Doppler Imager (MDI)
on board SOHO. Flow maps around the spots are also derived from
cross-correlation analysis of MDI continuum or TRACE white light and
used for comparison of photospheric flow patterns with the tracks of
moving magnetic features. An automated algorithm to find and track
unipolar concentrations of magnetic field was developed. Depending on
the velocity, size, and distance from the spot, a selected subset of all
concentrations can be identified as moving magnetic features (MMFs). Our
method finds 4-24 MMFs per hour around the spots, with higher counts
for larger sunspots. After being first detected, the MMFs have an
average flux content <Φ0>=2.5×1018
Mx. Their average lifetime is about 1 hr, but it takes a
concentration only tmax=25 minutes to reach its maximum
flux content of about <Φmax>=6.1×1018
Mx. MMFs are found to transport a net flux out of a spot at a rate of
(0.4-6.2)×1019 Mx hr-1: if sunspots were to decay
only by outflowing MMFs, it would take a sunspot of 1022
Mx one to several weeks to completely disassemble. The MMFs have
an initial velocity of 0>=1.8 km s-1, faster than the
average moat flow. Before merging into the moat region or surrounding
network, they travel a distance <Δ>=3.5 Mm. The tracks of the
individual MMFs correlate with the direction of local plasma flows and
sometimes display a spokelike pattern around the sunspots. We find an
average initial size 0>=1.7 Mm2, but the distribution
of sizes suggests features with a diameter of only 600-1000 km, which
would not be recognized by our algorithm. Comparison of a cotemporal,
cospatial magnetogram made with the Swedish Vacuum Solar Telescope
(SVST) on La Palma (with 12 times the spatial resolution) indicates
that unipolar magnetic fluxes in the MDI magnetogram may be comprised
of smaller elements with both polarities.
Title: Calibration and Tesing of the Tunable Filter on Solar B
Authors: Shine, R. A.; Title, A. M.; Tarbell, T. D.; Mitchell, K.;
Tavarez, L.; Rosenberg, W.
Bibcode: 2005AGUSMSP43A..04S
Altcode:
The tunable filter in the Focal Plane Package (FPP) on the Japanese
Solar B satellite, scheduled for launch in August 2006, was designed,
built, and tested at the Lockheed Martin Advanced Technology Center
(LMATC). It is an eight element wide field calcite filter (an improved
Lyot type) with a spectral resolution of about 100mÅ and a tuning range
of 11.87Å at 6302Å. Using 6 prefilters, it operates in bands covering
the 5172Å Fe I, 5250Å Fe I, 5576Å Fe I, 5896Å Na I, 6302Å Fe I,
and 6563Å H I lines. Here we describe the testing and calibrations
used to determine the tuning parameters as functions of temperature
and wavelength for the six bands. We also measure performance using
sunlight and laser sources in a standalone mode and integrated into
the FPP package. Images and derived magnetograms and Dopplergrams
using a low resolution solar image have also been obtained while
attached to the Solar B telescope and using a heliostat at the LMATC
in Palo Alto. In the course of this work we have also refined the
mathematical description for these types of filters, especially the
error terms that arise from residual misalignments. In particular,
we now believe we understand the intensity oscillations seen in this
and earlier Lyot tunable filters.
Title: Dynamics and Properties of Supergranulation from TRACE
Observations
Authors: Simon, G. W.; Shine, R. A.
Bibcode: 2004AAS...204.3718S
Altcode: 2004BAAS...36..712S
Using a unique set of white-light images taken by the Transition Region
and Corona Explorer (TRACE) satellite over a 7 day period in April 2000,
we investigate the properties and evolution of supergranulation. A
384x384 arcsec area of the solar photosphere was observed as it
rotated from Stonyhurst longitude 45E to 45W. Granulation is well
defined in these images which were taken at a 60s cadence for most
of the 7 days. Hence we are able to use local correlation tracking
(LCT) with sufficient spatial and temporal resolution to track both
mesogranules and supergranules. Improved techniques for LCT are
discussed and compared. Divergence and other parameters derived
from flow maps are used to identify and accurately trace supergranular
boundaries and tessellate the image areas into distinct supergranules
as well as smaller areas with less coherent flow patterns. We have
used these to derive sizes, lifetimes, and other properties of
supergranules. Motivated by recent work of Rast, Lisle, and Toomre
(2004), and Lisle, Rast, and Toomre (2004), we also present results
comparing the rotational rate of the supergranular and mesogranular
patterns and N/S alignments of these features. This work
was supported by NASA contract NAS5-38099, the Air Force Research
Laboratory, and the National Solar Observatory.
Title: Response of the Corona to Magnetic Activity in Underlying
Plage Regions
Authors: Ryutova, M.; Shine, R.
Bibcode: 2004ApJ...606..571R
Altcode:
We study the response of the solar corona to magnetic activity in the
underlying plage regions using high-resolution Michelson Doppler Imager
magnetograms co-aligned with multiwavelength images taken by TRACE at
chromospheric and coronal temperatures. We show that the EUV emission
above plage regions that are dominated by single-polarity magnetic
elements always has an amorphous shape that topologically mimics
the shape of the underlying plage. Spacetime slices of the amorphous
emission in the coronal lines show coherent braidlike structures with
almost constant period for a given area. Contrary to this, coronal
emission above mixed-polarity plages is highly discrete and consists
of sporadic localized radiative transients. As different regions of
strongly inhomogeneous corona evolve in different ways, separate
mechanisms for energy production, flow, and release are probably
required. We argue that in all cases the primary energy source lies
in continuous hydromagnetic activity among the photospheric magnetic
fields. The character of this activity determines the processes
of the extraction of energy and its transport throughout the solar
atmosphere. We propose a physical mechanism that may explain the diverse
properties of the UV/EUV emission in upper layers of atmosphere and
its relevance to the photospheric magnetic fields.
Title: Magnetic Coupling Between the Solar Surface and Corona:
Theory and Observations
Authors: Ryutova, Margarita; Shine, Richard
Bibcode: 2004AIPC..703..203R
Altcode:
Multi-wavelength observations taken simultaneously by several
instruments on the Solar and Heliospheric Observatory (SOHO)
and Transition Region and Coronal Explorer (TRACE) revealed a
clear connection between the photospheric magnetic fields and the
energetic events in the overlying atmosphere. We find that the EUV
coronal emission above the photosphere dominated by single polarity
magnetic elements is spongy in space and has coherent braid-like
structures in time. Contrary to these long living structures, corona
above the regions with mixed polarity magnetic elements is highly
discrete and consists of sporadic microflares, supersonic jets and
their combinations. We believe that in the unipolar magnetic regions
the energy flow from the surface to corona is associated with the
nonlinear collective phenomena in the ensemble of oscillating magnetic
flux tubes. These phenomena lead to formation of hot coronal ``clouds''
that have the properties of energetically open turbulence with tendency
to self-organization. Jets and microflares above the mixed polarity
regions are associated with shock waves produced by reconnecting
magnetic flux tubes in the photosphere and subsequent interaction of
shocks which leads to hydrodynamic cumulation of energy, which leads
to impulsive phenomena similar to shaped charges.
Title: Moving Magnet Features around Sunspots
Authors: Hagenaar, H. J.; Shine, R. A.
Bibcode: 2003AGUFMSH42B0544H
Altcode:
Moving magnetic features (MMF's) associated with small-scale emerging
fluxes near the sunspot penumbra are believed to play an important
role in mass and energy flow near sunspots. Since their discovery 30
year ago, only a few theoretical interpretations have been proposed on
the real identity of MMF's: they may be associated with field lines
detached from a decaying spot, or with closed magnetic loops. MMF's
have remained a difficult subject for observations, requiring high
spatial resolution movies for at least several hours. Coronal emission
does not show immediate response to the birth and disappearance of
individual MMF's; and the role of MMF's in the dynamics of upper layers
of the atmosphere remains unclear. We present the results of recent,
multi-wavelength observations designed to study the dynamics of MMF's
from the time of their emergence to the moment when they merge into
network or moat. Vector magnetograms made with the Dunn Telescope at
Sunspot, NM, are co-aligned with MDI magnetograms, and TRACE 1600 Å
and Fe IX/X 171 Å images, showing field orientation at the site of
emergence, and the response of the chromosphere and corona to dynamic
changes in the MMF's. These data allow meaningful statistics on MMF's
and their relation to sunspot evolution.
Title: Observations of Rotating Sunspots from TRACE
Authors: Brown, D. S.; Nightingale, R. W.; Alexander, D.; Schrijver,
C. J.; Metcalf, T. R.; Shine, R. A.; Title, A. M.; Wolfson, C. J.
Bibcode: 2003SoPh..216...79B
Altcode:
Recent observations from TRACE in the photospheric white-light channel
have shown sunspots that rotate up to 200° about their umbral centre
over a period of 3-5 days. The corresponding loops in the coronal fan
are often seen to twist and can erupt as flares. In an ongoing study,
seven cases of rotating sunspots have been identified, two of which
can be associated with sigmoid structures appearing in Yohkoh/SXT and
six with events seen by GOES. This paper analyzes the rotation rates
of the sunspots using TRACE white-light data. Observations from AR
9114 are presented in detail in the main text and a summary of the
results for the remaining six sunspots is presented in Appendixes
A-F. Discussion of the key results, particularly common features,
are presented, as well as possible mechanisms for sunspot rotation.
Title: Interaction and Dynamics of the Photospheric Network Magnetic
Elements
Authors: Ryutova, M.; Tarbell, T. D.; Shine, R.
Bibcode: 2003SoPh..213..231R
Altcode:
Small-scale magnetic elements in the quiet photospheric network are
believed to play a key role in the energy flow from the solar surface
to upper layers of atmosphere. Their intense hydro-magnetic activity
includes merging and fragmentation of same polarity fluxes, `total'
or partial cancellation of neighboring flux elements of opposite
polarity, dynamic appearance and disappearance of compact bipoles,
etc. We study the general features of these processes, and show
that non-collinearity of flux tubes, sharp stratification of low
atmosphere and finite plasma beta lead to several specific effects
in the interacting flux tubes that may explain the morphological
properties of network magnetic field and also provide a mechanism
for the energy build up and release in the nearby chromosphere and
transition region. We show that during the collision of flux tubes in
the photosphere reconnection occurs regardless of whether the flux
tubes are of opposite or of the same polarity. But the dynamics of
reconnection products are significantly different and lead to different
macroscopic effects that can be observed.
Title: Close Correlation among Hα Surges, Magnetic Flux
Cancellations, and UV Brightenings Found at the Edge of an Emerging
Flux Region
Authors: Yoshimura, Keiji; Kurokawa, Hiroki; Shimojo, Masumi; Shine,
Richard
Bibcode: 2003PASJ...55..313Y
Altcode:
Surge activities were observed at the edge of an emerging flux
region. We studied the relations between the features around the surges
in various data sets: magnetogram, Hα, G-band, UV, EUV, and soft
X-rays. We showed that the surge activities in Hα and the brightenings
in TRACE 1600Å images correlate well in both time and space with the
cancellation of magnetic fluxes around an emerging flux region. In
particular, at the onset of surge activity, a close correlation among
them was clearly found. These facts are consistent with the magnetic
reconnection model. The released energy through magnetic reconnection,
which is estimated to be 1028 erg, is sufficiently large
to produce surge activities. No prominent brightenings were observed
in soft X-ray and EUV images during the surge activities. This may
suggest that the energy releases occurred at a layer of high densities.
Title: Visualizing and Interpreting Very High Resolution Solar Movies
Authors: Shine, R. A.; Hurlburt, N.; Title, A. M.; Nightingale, R. W.
Bibcode: 2002AGUFMSH52A0498S
Altcode:
Benefiting from advances in detector technology, image compression,
and data storage capacities, current and upcoming solar instruments,
especially the Solar Dynamics Observatory (SDO) due to be launched in
2007, will produce immense amounts of data in the form of movies with
individual images in the 2048x2048 (4 Mpixel) to 4096x4096 (16 Mpixel)
range. This is beyond the capability of most contemporary computer
or video displays but several are now becoming available. In order to
develop concepts and software for working with existing and future data
sets, we have been working with a 9 Mpixel IBM T221 LCD display driven
by an SGI Octane 2 workstation. This is a desktop display with a 22
inch diagonal screen. We will demonstrate our prototype system using
several combinations of movies from the Swedish Vacuum Solar Tower
(SVST) at La Palma, and the TRACE and SOHO satellites and discuss some
approaches for the more challenging SDO data products.
Title: High Speed Reconnection in the Low Corona
Authors: Title, A. M.; Shine, R. A.; Schrijver, C. J.
Bibcode: 2002AGUFMSH52A0470T
Altcode:
High cadence observations taken with the Transition Region and Corona
Explorer (TRACE) instrument in the 1600Å\ band (with ≈~2 second
cadence) and in the Fe~IX/X 171Å\ band (≈~8 seconds cadence)
reveal fast reconnection events of several types. The most common
is a newly emerging magnetic loop that reconnects with an overlying
fan of loops. As the loops intersect, material is injected into the
overlying loops. A newly formed small bright condensation travels in
a helical path with a pitch angle of about 45 degrees and a speed of
700 to 1000 km/s. Movies of example events in both spectral bands will
be shown. This work was supported by NASA contract NAS5-38099.
Title: Estimating the Effects of JPEG Compression and Radiation on
the Accuracy of Vector Magnetic Fields Measurements for Solar-B
Authors: Lites, B.; Shine, R. A.; López Ariste, A.; Tarbell, T. D.
Bibcode: 2002AGUFMSH52A0471L
Altcode:
The Japanese Solar-B satellite, currently scheduled for launch in
September 2005, includes a spectro-polarimeter (SP) to precisely measure
the full Stokes polarization vector (I,Q,U,V) in the Fe I lines at
6302Å. These will be processed to produce vector magnetograms of the
solar surface using algorithms based on those for the Advanced Stokes
Polarimeter (ASP) as described in Skumanich, et al, 1997, ApJ Suppl
110. Accumulations of the raw images into time averaged I,Q,U,V images
will be done on board and the results will be 12 bit JPEG compressed to
make the best use of the available telemetry. Hence a single radiation
hit in a raw image affects the entire time average at that point. Also,
radiation spikes affect JPEG compression performance. Because of
concerns about these effects, we simulated them separately and in
combination using ASP data and radiation level measurements from the
TRACE satellite. Like TRACE, Solar-B will fly in a high inclination,
sun synchronous orbit and be exposed to radiation from the polar
radiation belts as well as the SAA. Since the SP detector will be
better shielded than that on TRACE, we hope that these will be an over
estimate of the effects. The results from the simulations are very
encouraging. We find that for active region magnetic fields we can use
JPEG to compress the data volume by more than a factor of 10 without
compromising the accuracy of the inferred magnetic field vector. The
radiation in the polar regions has little effect and even the much
stronger SAA radiation causes average perturbations that are less than
the formal errors for sunspot fields and about twice the formal errors
for plage fields. However, very weak field measurements will benefit
from less lossy compression and periods of low radiation. Of course,
the very strong radiation hits always produce artifacts. Compression
performance is affected only slightly so it will not be necessary to
avoid observations in the SAA because of excessive telemetry usage. This
work was supported by NASA contract NAS8-01002.
Title: TRACE, SOHO/EIT, and SOHO/MDI Observations of AR0030, Including
Rotating Sunspots and the July 15, 2002 X3.0 Flare in Ultraviolet
and Extreme Ultraviolet
Authors: Nightingale, R. W.; Shine, R. A.; Alexander, D.; Freeland,
S. L.; Frank, Z. A.; Brown, D. S.
Bibcode: 2002AGUFMSH52A0467N
Altcode:
On July 15, 2002 TRACE and several SOHO instruments observed an X3.0
flare in AR0030 near 2000 UT. During this period TRACE was primarily
observing in its 1600Å ultraviolet (UV) channel (most sensitive
to temperatures around 100,000 K in the flare). The 195Å extreme
ultraviolet (EUV) channel of SOHO/EIT (which is most sensitive to about
1.6 MK) will be utilized in this poster, in addition to the magnetic
field measurements of SOHO/MDI during this event period. TRACE followed
the active region for over 10 days, starting about 4 days before the
flare. Broadband white light TRACE images of the photosphere indicate
that one or more of the sunspots were rotating, a possible precursor to
the flare. Images and movies of AR0030 in the various wavelengths will
be shown. The flare region was so intense in the TRACE UV that it is
very difficult to show both the quiescent and flaring regions, so the UV
movie will focus on the flaring plasma with its 2 eruptions. In the EIT
EUV, more coronal structure away from the flare can be seen. Analysis
of the rotational rates of the sunspots will be given along with their
possible coupling to the flare. This work was supported by NASA under
contract NAS5-38099.
Title: Observations of rotating sunspots and their effect in the
corona
Authors: Brown, D. S.; Nightingale, R. W.; Alexander, D.; Schrijver,
C. J.; Metcalf, T. R.; Shine, R. A.; Title, A. M.; Wolfson, C. J.
Bibcode: 2002ESASP.505..261B
Altcode: 2002IAUCo.188..261B; 2002solm.conf..261B
Recent observations from TRACE have seen sunspots, in the photospheric
white light filter, rotate up to 180 degrees about their umbral
centre. The corresponding loops in the coronal fan are seen to twist
and can erupt. In an ongoing study, five cases of rotating sunspots
have been identified, three of which can be identified with sigmoid
structures appearing in Yohkoh/SXT. This paper will present images from
one of these events, showing the coupling between the photosphere and
the corona, and observational analysis deducing the rotation speeds
and how they change through time and with radius of the sunspot. In
particular, the paper will focus on the best example of a rotating
sunspot observed so far, that of AR 9114 which occurred over 8-10 August
2000 and was observed by TRACE, SoHO/MDI and Yohkoh/SXT. The sunspot
rotated 150 degrees within this time and is associated with a sigmoid.
Title: Photospheric Magnetic Activities Responsible for Soft
X-Ray Pointlike Microflares. I. Identifications of Associated
Photospheric/Chromospheric Activities
Authors: Shimizu, T.; Shine, R. A.; Title, A. M.; Tarbell, T. D.;
Frank, Z.
Bibcode: 2002ApJ...574.1074S
Altcode:
By combining Yohkoh soft X-ray images with high-resolution magnetograms
simultaneously obtained at La Palma, we studied photospheric magnetic
signatures responsible for soft X-ray microflares (active-region
transient brightenings). In order to have a reliable correspondence
between the photosphere and the corona, we studied 16 pointlike
transient brightenings with X-ray source size less than 10" occurring
during periods when the seeing was excellent at La Palma, although a
lot of transient brightenings were in forms of multiple- or single-loop
structures. In half of the studied events, small-scale emergences
of magnetic flux loops are found in the vicinity of the transient
brightenings. Six events of that half show that a small-scale flux
emergence accompanies the X-ray brightening 5-30 minutes prior to
its onset. In the other half of the studied events, no apparent
evolutionary change of magnetic flux elements is found associated
with the transient brightenings. Many of these events are found in
rather strong magnetic fields, such as sunspots and pores, implying
that small-scale changes of magnetic flux are obscured or suppressed
by strong magnetic fields. The horizontal plasma flows derived from
local cross-correlation tracking of granules in continuum images are
suppressed at the feet of some X-ray transient brightenings.
Title: Concurrent Rotating Sunspots, Twisted Coronal Fans, Simgoid
Structures and Coronal Mass Ejections
Authors: Nightingale, R. W.; Brown, D. S.; Metcalf, T. R.; Schrijver,
C. J.; Shine, R. A.; Title, A. M.; Wolfson, C. J.
Bibcode: 2002mwoc.conf..149N
Altcode:
In an on-going study, several sunspots, in apparent rotation, have
been identified in TRACE photospheric white light (WL) images with
accompanying twisting of coronal fans in the corresponding EUV (171,
195 AA) images. These observations can also be temporally and spatially
associated with S or inverse-S shaped regions (sigmoid structures)
appearing in Yohkoh SXT images and with concurrent coronal mass
ejections (CMEs) and/or flares. We have determined the rotational
speed of the apparently rotating sunspot in AR 9114 over 8-10 August
2000, established the inverse S shape observed in the SXT data, and
viewed a rapid, bright flash of possible reconnection in a TRACE
EUV movie. A CME was observed during the 15-18 August 1999 event,
which also included an inverse S shaped region in the SXT data, and
a rotating sunspot and twisting coronal fans in the TRACE data. The
large Bastille Day CME event of 14 July 2000 was accompanied by one
or more apparently rotating sunspots as observed in TRACE WL and by
an inverse S shaped region as seen in a difference SXT image. Movies
and plots of some of these data will be shown along with flow maps and
a list of the pertinent parameters for several rotating sunspots. We
will report on our attempt to determine the vertical electric current
flowing through the 8 August 2000 sunspot utilizing the Mees vector
magnetograph data in order to better understand the apparent rotation
"driver". These observations display the coupling of the solar magnetic
field from the photosphere into the corona.
Title: Pre-Flare Heating Around the Temperature Minimum Region Found
Right Prior to an X-Class Flare
Authors: Kurokawa, H.; Ishii, T. T.; Wang, T. J.; Shine, R.
Bibcode: 2002mwoc.conf..257K
Altcode:
Studies of magnetic shear developments and pre-flare activities in
flare-productive sunspot regions are fundamentally important for the
study of flare energy build-up and energy release mechanism. Several
previous works demonstrated that the emergence of a twisted magnetic
flux rope, which is originally formed in the convection zone, must be
the source of the strong magnetic shear development in a sunspot region
to produce a strong flare activity (Kurokawa 1987, Tanaka 1991, Ishii et
al. 2000). We are still, however, far from sufficiently understanding
how the twisted structures of a magnetic flux rope is formed in the
convection zone, and where and how such a twisted magnetic rope untwists
and releases its energy as flaresNULL A flare productive active region
NOAA 9026, which showed an interesting evolution during a coordinated
observation between the Domeless Solar Telescope of Hida Observatory,
Swedish Telescope of La Palma, and TRACE Satellite from 3 through 12
June of 2000, provided us a rare opportunity to study a new important
aspect of a twisted magnetic flux rope and its rapidly-untwisted motions
to have caused strong flares. From the analyses of the evolution of
this region, we first found a clear evidence of pre-flare heating or
energy release from the upper photosphere through the lower chromosphere
from about two hours before the energy release in the corona as an
X-class flare. We suggest that this pre-flare energy release in the
lower atmosphere is closely related to the emergence of the twisted
magnetic flux rope from below the photosphere.
Title: Surges, Magnetic Flux Cancellations, and UV Brightenings
around an Emerging Flux Region
Authors: Yoshimura, K.; Kurokawa, H.; Shimojo, M.; Shine, R.
Bibcode: 2002mwoc.conf...99Y
Altcode:
Surge activities, which are observed in Hα images, have been
studying for a long time. Many authors noticed that cancellations
of magnetic flux was an important factor for surge activities and
proposed the models based on magnetic reconnection. But there are not
many observations which have enough cadence for comparison changes
of magnetic field with surge activities. So the correlation between
surges and magnetic flux cancellations is not clear yet. (ex. Zhang
et al. 2001) We studied the temporal and spatial relations between
surge activities and other phenomena which may be accompanied by surge
activities. The data we used here are from coordinated observation with
Swedish Vacuum Solar Telescope on La Palma, TRACE and SOHO/MDI. So
high cadence images for the same target are available in various
wavelengths. MDI, for example, took magnetogram data every one minutes
with high resolution mode at that time. The main results from this study
are as follows: (1) We can not find any large time lag between the onset
of the surge and of the magnetic fields cancellation. This is a conflict
result against the one in Zhang et al. (2) There were UV brightenings
which correlated well with rapid cancellation of magnetic fields. (3)
The UV brightenings located just on neutral lines with some displacement
from the region where rapid magnetic cancellation occurred. These
observational fact can be explained by magnetic reconnection model.
Title: Dynamics of the solar chromosphere. III. Ultraviolet brightness
oscillations from TRACE
Authors: Krijger, J. M.; Rutten, R. J.; Lites, B. W.; Straus, Th.;
Shine, R. A.; Tarbell, T. D.
Bibcode: 2001A&A...379.1052K
Altcode:
We analyze oscillations in the solar atmosphere using image sequences
from the Transition Region and Coronal Explorer (TRACE) in three
ultraviolet passbands which sample the upper solar photosphere and
low chromosphere. We exploit the absence of atmospheric seeing in
TRACE data to furnish comprehensive Fourier diagnostics (amplitude
maps, phase-difference spectra, spatio-temporal decomposition) for
quiet-Sun network and internetwork areas with excellent sampling
statistics. Comparison displays from the ground-based Ca Ii H
spectrometry that was numerically reproduced by Carlsson &
Stein are added to link our results to the acoustic shock dynamics
in this simulation. The TRACE image sequences confirm the dichotomy
in oscillatory behaviour between network and internetwork and show
upward propagation above the cutoff frequency, the onset of acoustic
shock formation in the upper photosphere, phase-difference contrast
between pseudo-mode ridges and the interridge background, enhanced
three-minute modulation aureoles around network patches, a persistent
low-intensity background pattern largely made up of internal gravity
waves, ubiquitous magnetic flashers, and low-lying magnetic canopies
with much low-frequency modulation. The spatio-temporal occurrence
pattern of internetwork grains is found to be dominated by acoustic
and gravity wave interference. We find no sign of the high-frequency
sound waves that have been proposed to heat the quiet chromosphere, but
such measurement is hampered by non-simultaneous imaging in different
passbands. We also find no signature of particular low-frequency
fluxtube waves that have been proposed to heat the network. However,
internal gravity waves may play a role in their excitation.
Title: Flow Map Studies of Supergranule and Mesogranule Evolution
from TRACE
Authors: Shine, R. A.; Frank, Z. A.; Tarbell, T. D.; Simon, G. W.
Bibcode: 2001AGUFMSH11A0702S
Altcode:
From 00:44 UT 22-April-2000 to 00:09 UT 29-April-2000 we obtained a
nearly continuous set of white light images using the Transition Region
and Corona Explorer (TRACE) satellite. A 384x384 arc second field of
view was used that tracked solar rotation from Stonyhurst longitudes
45E to 45W along the solar equator. The total time is nearly 7 days
with images taken every minute over most of the interval. The largest
temporal gap was 45m and there were only 9 gaps longer than 10m. The
area was mostly free of active regions. These images are broad band
white light with 0.5 arc second pixels. Granulation is well defined and
we used local correlation techniques (LCT) to compute flow maps of the
horizontal velocities with a resolution of about 5 arc seconds. The flow
map resolution and quality suffer somewhat near the longitude extrema
but the maps are usable throughout the 7 days to define supergranules
and mesogranules. We compute horizontal divergence to study the motions
of mesogranules and the evolution and lifetime of supergranules. When
enough telemetry capacity was available, we also obtained co-spatial
images in the TRACE Fe IX/X 171Å channel and the 1600Å channel. We
use these to study the response of the corona and chromosphere to the
photospheric motions. During times with particularly high telemetry
throughput, we took white light images every 30 seconds. This allows
us to empirically determine the noise in our flow maps using two
interleaved and disjoint sets of white light data, each with one minute
intervals. This work was supported by NASA contract NAS5-38099.
Title: A Prototype Problem-Solving Environment for Living With a
Star Data
Authors: Hurlburt, N.; Freeland, S.; Shine, R.; Bose, P.
Bibcode: 2001AGUFMSH31A0702H
Altcode:
The Living With a Star program aims to understanding our space
environment as a unified system. For this approach to be successful,
the scientific working environment must present the LWS components
as a unified whole. We present an architecture and data assimilation
environment which addresses this critical issue. The goal of our
Problem-Solving Environment for Living With a Star (PSELWS) project is
to place the users of the data at center stage -- providing a virtual
workbench with the tools, and infrastructure needed for seamless,
timely and efficient access to the various data sources.
Title: More Rotating Sunspot Observations by TRACE With Twisting
EUV Coronal Fans
Authors: Nightingale, R. W.; Shine, R. A.; Brown, D. S.; Wolfson,
C. J.; Frank, Z. A.; Title, A. M.
Bibcode: 2001AGUSM..SH41B11N
Altcode:
In an on-going search several sunspots, rotating about their umbral
centers, have been identified in TRACE photospheric white light (WL)
images. In many cases the rotation can also be seen in the corresponding
UV (1600 Å) and/or EUV (171, 195 Å) images. Preliminary analysis of
one such rotating sunspot and the coronal response to the rotation,
observed in AR9114 on August 8-10, 2000, was presented at the fall
AGU meeting (Nightingale et al., Abstract SH11A-10, EOS, AGU 2000 Fall
Meeting, Vol. 81, p. F977, Nov. 2000). Further detailed analysis and
modeling of this event, where loops appear to cross over one another,
is in progress. Meanwhile, we are finding other examples within the
TRACE data set. Twisting EUV coronal fans have been observed above
rotating sunspots on August 16, 1999 for AR8667, where a sigmoid was
visible in Yohkoh SXT data, and on May 20, 2000. Several rotating
sunspots were also seen in the active region of the July 14, 2000
Bastille Day event. More recent rotations observed only in WL and UV
occurred on December 11 and 22, 2000. Movies of some of these rotations
will be shown, as well as magnetic field data from MDI on SOHO where
available. Analysis of the rotational rates of the sunspots will be
given. These observations display the coupling of the magnetic field
from the photosphere into the corona. This work was supported by NASA
under contract NAS5-38099.
Title: Formation of Compact Coronal Structures Associated with the
Emerging Magnetic Flux
Authors: Ryutova, M. P.; Shine, R.; Tarbell, T. D.
Bibcode: 2001AGUSM..SH32C01R
Altcode:
We study the events associated with the emergence of magnetic flux
in the photosphere occurring throughout the solar atmosphere from
its surface up to the low corona using coordinated observations from
Swedish Vacuum Solar Telescope (SVST) on La Palma, the TRACE satellite
and the MDI instrument on SOHO. The object of the observations is a
plage dominated initially (UT 08:01:03, June 10, 1999) by positive
polarity elements with about 0.3 magnetic filling factor near the
same polarity sunspot. High resolution MDI magnetograms are assembled
in a 6-hour movie and co-aligned with TRACE Fe IX/X 171 Å images of
the corona, SVST Ca II K-line images showing the low chromosphere and
Hα filtergrams showing plasma motions higher in the chromosphere. To
study line of sight motions, we used filtergrams taken in the +/- 350
~mÅ (and +/- 700 ~mÅ) wings of Hα . During the first two hours,
there are almost no changes (at the MDI resolution) in the initial
magnetic field pattern of studied region, and the 171 Å emission
above this region shows stable amorphous structures. Then a series of
events lead to the formation of two opposite polarity pores in the
target region and compact coronal loops above it with the following
chronology. First, opposite polarity small-scale flux tubes emerge
and interact with the existing plage elements. This is followed almost
immediately by strong Hα surges, whose peak activity lasts about 10
minutes. After this lag, enhanced emission in 171 Å takes the form
of a short-lived transient. During the next one hour (long before
the pore and compact coronal loops form), there are several new Hα
surges and coronal plasma jets whose activity correlates well with
remarkable changes in the photospheric fluxes which eventually form
pores. For a quantitative analysis we apply a theoretical model of
energy transport from subsurface motions associated with the emerging
magnetic flux. Strong disturbances generated in a limited surface
area may propagate upward like blast waves along a cone. This in
turn may cause a sequence of phenomena associated with forward and
reflected shocks, whose signatures are similar to the observations. The
process may last as long as significant changes in the photospheric
magnetic field occur, until it is suppressed by the strong fields in
the pores. Under some condition the established pore structure may
be accompanied by a current drive which leads to formation of the
coronal loops.
Title: Sunspots: Moving Magnetic Features and Moat Flow
Authors: Shine, R.; Title, A.
Bibcode: 2000eaa..bookE2038S
Altcode:
Most mature SUNSPOTS and some large SUNSPOT PORES are surrounded, at
least in part, by a zone which is free of stationary magnetic field
(e.g. PLAGE, network) and which exhibits a radially outward horizontal
mass flow. This zone is called a sunspot `moat'. The most notable
features in the moat are small magnetic structures of mixed polarity
called moving magnetic features (MMFs). These are trans...
Title: Sunspot Oscillations from the Photosphere to the Corona
Authors: Shine, R. A.
Bibcode: 2000SPD....31.0303S
Altcode: 2000BAAS...32Q.834S
Denied the radiative splendor of the rest of the solar surface, sunspots
seem to be compensated with more vigorous oscillations above their
dark interiors. The observational properties of these oscillations
will be reviewed along with some possibilities for employing them
to study sunspot structure. The most obvious of these phenomena
are the umbral oscillations and penumbral running waves seen in the
chromosphere. Discovered in the late 1960's, umbral oscillations exhibit
well documented non-linear behavior leading to shocks and umbral flashes
in the upper chromosphere and transition region. Periods are typically
150 - 180s and are thought to be driven by photospheric motions. Running
penumbral waves, best seen in H alpha or Na I D Dopplergrams, have
periods near 250s and move outward in the penumbra with horizontal
velocities from 10 - 25 km/s. Observations with the SMM/UVSP instrument
showed that sunspot oscillations extended into the transition region
and recent results from the CDS and SUMER instruments on SOHO show
this in much more detail. The TRACE satellite has shown that coronal
EUV loops (Fe IX 171 Angstroms and Fe X 195 Angstroms) originating
in sunspots exhibit prominent intensity oscillations wherever they
overlay the photospheric penumbra or umbra. Loops not associated with
sunspots occasionally show similar oscillations but most do not. Some
recent coordinated TRACE and H alpha observations (from the SVST on
La Palma) will be presented to establish the relationships between the
chromospheric and coronal oscillations. This work is supported by the
TRACE and SOI/MDI projects at LMSAL and Stanford (contract NAS5-38099
and grant NAG5-3077).
Title: TRACE Observations of Active Region Births
Authors: Wolfson, C. J.; Shine, R. A.
Bibcode: 2000SPD....31.0142W
Altcode: 2000BAAS...32..808W
TRACE has recorded the births of a few bona-fide active regions, as
well as many ephemeral regions and so-called X-ray bright points. The
observations have usually been made serendipitously while studying a
nearby, well formed active region. However, a couple of events have
been recorded when deliberately looking for emerging flux in quiet
portions of an active region belt. This poster will discuss some
of the best observations to date, where the quality ranking of the
observation is closely coupled to the observing mode TRACE was in
and the availability of high resolution (temporal and/or spatial)
MDI magnetograms. Included will be the birth of NOAA AR#8699 on 11
September 1999 at about 14 UT (N22E34), AR#8637 on 17 July 1999 at about
4 UT (N11W1), and AR#8885 on 21 February 2000 at about 6 UT (N11W7);
these specifics being provided to encourage coordination with other
observations. The temporal relationships between the first appearances
of magnetic bipoles, EUV loops, chromospheric plage, pores, and sunspots
will be discussed as will the growth rate and spatial relationships
of these different features and any associated photospheric flows.
Title: Coordinated MDI/TRACE/SVST Observations of Sunspots
Authors: Bush, R. I.; Shine, R. A.; Brandt, P.; Sobotka, M.;
Scharmer, G.
Bibcode: 2000SPD....31.0122B
Altcode: 2000BAAS...32R.804B
During the first two weeks of June 1999, coordinated observations
of sunspots were made by the MDI instrument on the SOHO spacecraft,
the TRACE satellite and the Swedish Vacuum Solar Tower (SVST) at La
Palma. The MDI instrument was operating in a "high resolution" mode
and was obtaining 1.2 arc-second resolution magnetograms and 2.4
arc-second resolution dopplergrams at a one minute cadence. TRACE
observations were made in Fe IX/X 171 Angstroms and/or Fe XII 195
Angstroms together with the 1600 Angstroms and continuum bands at a
1.0 arc-second resolution. The SVST data consist of filtergrams taken
with three 2Kx2K CCD cameras with about 0.4 arc-second resolution
operating in frame selection mode. The first camera used a fixed G
band (4305 Angstroms) filter, the second a fixed blue continuum filter
(4507 Angstroms), and the third a narrow band tunable filter which was
cycled through several positions in the Hα line and the 6302 Angstroms
Fe ~I line. The goal of this investigation is to detail the evolution
of stable sunspots in order to understand the detailed correlation of
photospheric flows and magnetic features. The high time and spatial
resolution of these measurements provides a unique opportunity to
explore the interactions of plasma and magnetic field at the solar
surface. This work was supported by NASA grant NAG5-3077 at Stanford
and NASA contract NAS5-38099 at Lockheed Martin.
Title: Electro-Mechanical Coupling Between the Photosphere and
Transition Region
Authors: Tarbell, T. D.; Ryutova, M.; Shine, R.
Bibcode: 2000SoPh..193..195T
Altcode:
We study the response of the chromosphere and transition region to
dynamic changes in the photospheric network magnetic fields. We present
results from simultaneous measurements taken by TRACE in chromospheric
and transition region (C iv) images, high-resolution magnetograms taken
by MDI, and spectra of chromospheric (C ii) and transition region
lines (O vi) obtained with the SUMER instrument on SOHO. Enhanced
emission in the C iv line is generally co-spatial with the magnetic
pattern in the photosphere. We propose a mechanism of electro-mechanical
coupling between the photosphere and upper layers of atmosphere based on
hydrodynamic cumulation of energy produced by reconnecting flux tubes in
the photosphere/chromosphere region (Tarbell et al., 1999). We believe
that a basic process causing energetic events is the cascade of shock
waves produced by colliding and reconnecting flux tubes. The continuous
supply of flux tubes in the `magnetic carpet' ensures the ubiquitous
nature of this process and its imprint on the upper atmosphere. The
appearance of bright transients often, but not always, correlates with
canceling mixed polarity magnetic elements in the photosphere. In
other cases, transients occur in regions of unipolar flux tubes,
suggesting reconnection of oblique components. Transients are also
seen in regions with no fields detected with the MDI sensitivity;
these may be reconnections of tiny features with diameters less than
100 km. Blinkers and other bright transients are often accompanied by
two directional plasma jets. These may be generated by cylindrical
self-focusing of shock fronts or by collision of shocks produced by
neighboring reconnection processes. The observations suggest that
stronger emissions correspond to lower velocity jets, and vice versa;
this property is a natural consequence of the proposed mechanism. Plasma
flows are always seen whenever the slit crosses strong magnetic flux
tubes or vertices of converging flows in the supergranular network. The
overall energy distribution between heating and plasma flows is an
intrinsic feature of our mechanism.
Title: Supergranule and Mesogranule Evolution
Authors: Shine, R. A.; Simon, G. W.; Hurlburt, N. E.
Bibcode: 2000SoPh..193..313S
Altcode:
The MDI instrument on the SOHO satellite obtained a nearly continuous
45.5-hr run in high-resolution mode on 17-18 January 1997, collecting
continuum, Dopplergram, and magnetogram images once per minute. This
is one of the longest data sets yet obtained in this mode and shows
significant evolution of the supergranulation pattern. After allowing
for solar rotation within the fixed field of view, an area spanning
17° in latitude and 11° in longitude was extracted that covers
the same area of the solar surface for the entire run. From the
de-rotated continuum images, we computed flow maps of photospheric
motions using local correlation techniques (LCT). Horizontal divergence
maps constructed from the flow maps show local maxima of the size of
mesogranules (5-10''). We interpret these as mesogranules although
the LCT flow map resolution (4.8'' FWHM) may not completely resolve
smaller mesogranules. Movies made from the divergence maps clearly show
the outward convection (advection) of these mesogranules within each
supergranule, and narrow boundaries of negative divergence outlining the
supergranules. Several new supergranules are observed forming. These
appear as areas of strong divergence that pop up between pre-existing
supergranules and grow, pushing their neighbors apart. Others seem
to perish between growing neighbors. We also computed the vertical
component of vorticity from the flow maps. Movies of this vorticity
do not show any obvious patterns.
Title: Bright Chromospheric Grains and the Magnetic Intranetwork
Authors: Worden, John; Harvey, John; Shine, Richard
Bibcode: 1999ApJ...523..450W
Altcode:
We compare bright grains in the cell interiors of the chromospheric
network with intranetwork magnetic field elements using images from the
Transition Region and Coronal Explorer Satellite (TRACE) taken at H I
Lyα (121.6 nm) (chromosphere) and the continuum at 160 nm (temperature
minimum).We find only a random correspondence between bright cell
grains and regions of intranetwork magnetic flux as seen in these two
emissions. In addition, we find that the 160.0 nm cell grains that do
overlay magnetic intranetwork show no correlation between intensity and
magnetic field strength. However, it is possible that Lyα bright cell
grains that overlay magnetic fields may show a slight enhancement in
intensity. Our results suggest that the intranetwork magnetic field is
essentially uninvolved with the production of cell grains in the upper
photosphere/lower chromosphere but could have a small involvement with
bright cell grains in the chromosphere/transition region.
Title: A new view of the solar outer atmosphere by the Transition
Region and Coronal Explorer
Authors: Schrijver, C. J.; Title, A. M.; Berger, T. E.; Fletcher, L.;
Hurlburt, N. E.; Nightingale, R. W.; Shine, R. A.; Tarbell, T. D.;
Wolfson, J.; Golub, L.; Bookbinder, J. A.; DeLuca, E. E.; McMullen,
R. A.; Warren, H. P.; Kankelborg, C. C.; Handy, B. N.; De Pontieu, B.
Bibcode: 1999SoPh..187..261S
Altcode:
The Transition Region and Coronal Explorer (TRACE) - described in the
companion paper by Handy et al. (1999) - provides an unprecedented
view of the solar outer atmosphere. In this overview, we discuss the
initial impressions gained from, and interpretations of, the first
million images taken with TRACE. We address, among other topics,
the fine structure of the corona, the larger-scale thermal trends,
the evolution of the corona over quiet and active regions, the high
incidence of chromospheric material dynamically embedded in the coronal
environment, the dynamics and structure of the conductively dominated
transition region between chromosphere and corona, loop oscillations
and flows, and sunspot coronal loops. With TRACE we observe a corona
that is extremely dynamic and full of flows and wave phenomena, in
which loops evolve rapidly in temperature, with associated changes in
density. This dynamic nature points to a high degree of spatio-temporal
variability even under conditions that traditionally have been referred
to as quiescent. This variability requires that coronal heating can
turn on and off on a time scale of minutes or less along field-line
bundles with cross sections at or below the instrumental resolution
of 700 km. Loops seen at 171 Å (∼1 MK) appear to meander through
the coronal volume, but it is unclear whether this is caused by the
evolution of the field or by the weaving of the heating through the
coronal volume, shifting around for periods of up to a few tens of
minutes and lighting up subsequent field lines. We discuss evidence
that the heating occurs predominantly within the first 10 to 20 Mm
from the loop footpoints. This causes the inner parts of active-region
coronae to have a higher average temperature than the outer domains.
Title: The transition region and coronal explorer
Authors: Handy, B. N.; Acton, L. W.; Kankelborg, C. C.; Wolfson, C. J.;
Akin, D. J.; Bruner, M. E.; Caravalho, R.; Catura, R. C.; Chevalier,
R.; Duncan, D. W.; Edwards, C. G.; Feinstein, C. N.; Freeland, S. L.;
Friedlaender, F. M.; Hoffmann, C. H.; Hurlburt, N. E.; Jurcevich,
B. K.; Katz, N. L.; Kelly, G. A.; Lemen, J. R.; Levay, M.; Lindgren,
R. W.; Mathur, D. P.; Meyer, S. B.; Morrison, S. J.; Morrison, M. D.;
Nightingale, R. W.; Pope, T. P.; Rehse, R. A.; Schrijver, C. J.;
Shine, R. A.; Shing, L.; Strong, K. T.; Tarbell, T. D.; Title, A. M.;
Torgerson, D. D.; Golub, L.; Bookbinder, J. A.; Caldwell, D.; Cheimets,
P. N.; Davis, W. N.; Deluca, E. E.; McMullen, R. A.; Warren, H. P.;
Amato, D.; Fisher, R.; Maldonado, H.; Parkinson, C.
Bibcode: 1999SoPh..187..229H
Altcode:
The Transition Region and Coronal Explorer (TRACE) satellite, launched
2 April 1998, is a NASA Small Explorer (SMEX) that images the solar
photosphere, transition region and corona with unprecedented spatial
resolution and temporal continuity. To provide continuous coverage
of solar phenomena, TRACE is located in a sun-synchronous polar
orbit. The ∼700 Mbytes of data which are collected daily are made
available for unrestricted use within a few days of observation. The
instrument features a 30-cm Cassegrain telescope with a field of view
of 8.5×.5 arc min and a spatial resolution of 1 arc sec (0.5 arc sec
pixels). TRACE contains multilayer optics and a lumogen-coated CCD
detector to record three EUV wavelengths and several UV wavelengths. It
observes plasmas at selected temperatures from 6000 K to 10 MK with
a typical temporal resolution of less than 1 min.
Title: A new view of the solar corona from the transition region
and coronal explorer (TRACE)
Authors: Golub, L.; Bookbinder, J.; Deluca, E.; Karovska, M.; Warren,
H.; Schrijver, C. J.; Shine, R.; Tarbell, T.; Title, A.; Wolfson,
J.; Handy, B.; Kankelborg, C.
Bibcode: 1999PhPl....6.2205G
Altcode:
The TRACE Observatory is the first solar-observing satellite in the
National Aeronautics and Space Administration's (NASA) Small Explorer
series. Launched April 2, 1998, it is providing views of the solar
transition region and low corona with unprecedented spatial and
temporal resolution. The corona is now seen to be highly filamented,
and filled with flows and other dynamic processes. Structure is seen
down to the resolution limit of the instrument, while variability and
motions are observed at all spatial locations in the solar atmosphere,
and on very short time scales. Flares and shock waves are observed,
and the formation of long-lived coronal structures, with consequent
implications for coronal heating models, has been seen. This overview
describes the instrument and presents some preliminary results from
the first six months of operation.
Title: Observations of Filaments
Authors: Title, A.; Schrijver, C.; Tarbell, T.; Shine, R.
Bibcode: 1999AAS...194.7905T
Altcode: 1999BAAS...31..963T
Filaments are clearly seen as absorption features in the TRACE FE
IX and XII images. Because of the 24 hour coverage of TRACE many
filaments have been observed on the disk and near the limb, and as
quiescent and active structures. A quiescent filament consists of many
parallel strands the run nearly parallel to the surface. The strands
are often at the TRACE resolution and are always in motion. Adjacent
strands often exhibit flows in opposite directions with speeds of
10 to 40 km/second. Filaments occasionally erupt explosive from the
surface. The initial accelerations have not been observed with a 30
second cadence. Velocities in the initial phase range between 200
and 400 km/s. Filaments are observed to erupt and travel out of the
TRACE field of view, erupt and fall back to the solar surface, and
erupt and travel a short distance before being constraint by overlying
fields. Examples of the dynamic structure of filaments and their modes
of eruption will be demonstrated in a video presentation.
Title: Dispersal of Magnetic Flux in the Quiet Solar Photosphere
Authors: Hagenaar, H. J.; Schrijver, C. J.; Title, A. M.; Shine, R. A.
Bibcode: 1999ApJ...511..932H
Altcode:
We study the random walk of magnetic flux concentrations on two
sequences of high-resolution magnetograms, observed with the Michelson
Doppler Imager on board SOHO. The flux contained in the concentrations
ranges from |Φ|=1018 Mx to |Φ|=1019 Mx, with
an average of |Φ|=2.5×1018 Mx. Larger concentrations tend
to move slower and live longer than smaller ones. On short timescales,
the observed mean-square displacements are consistent with a random
walk, characterized by a diffusion coefficient D(t<10 ks)=70-90
km2 s-1. On longer timescales, the diffusion
coefficient increases to D(t>30 ks)=200-250 km2
s-1, approaching the measurements for a five-day set of Big
Bear magnetograms, D~=250 km2 s-1. The transition
between the low and large diffusion coefficients is explained with
a model and simulations of the motions of test particles, subject to
random displacements on both the granular and supergranular scales,
simultaneously. In this model, the supergranular flow acts as a
negligible drift on short timescale, but dominates the granular
diffusion on longer timescales. We also investigate the possibility
that concentrations are temporarily confined, as if they were caught
in supergranular vertices, that form short-lived, relatively stable
environments. The best agreement of model and data is found for step
lengths of 0.5 and 8.5 Mm, associated evolution times of 14 minutes
and 24 hr, and a confinement time of no more than a few hours. On
our longest timescale, DSim(t>105)-->285
km2 s-1, which is the sum of the small- and
large-scale diffusion coefficients. Models of random walk diffusion on
the solar surface require a larger value: DWang=600+/-200
km2 s-1. One possible explanation for the
difference is a bias in our measurements to the longest lived, and
therefore slower concentrations in our data sets. Another possibility
is the presence of an additional, much larger diffusive scale.
Title: Dynamics of the Quiet Solar Chromosphere
Authors: Rutten, R. J.; Lites, B. W.; Berger, T. E.; Shine, R. A.
Bibcode: 1999ASPC..158..249R
Altcode: 1999ssa..conf..249R
No abstract at ADS
Title: Supergranule and Mesogranule Evolution
Authors: Shine, Richard; Simon, George; Hurlburt, Neal
Bibcode: 1999soho....9E..15S
Altcode:
The MDI instrument on the SoHO satellite obtained a nearly continuous
46-hour run in high resolution mode on January 17 to 18, 1997,
collecting continuum, dopplergram, and magnetogram images once per
minute. This is one of the longest data sets yet obtained in this mode
and shows significant evolution of the supergranulation pattern. After
allowing for solar rotation within the fixed field of view, an area
spanning 13 degrees in latitude and 10 degrees in longitude was
extracted that covers the same area of the solar surface for the 46
hours. Using the derotated continuum images, we computed flow maps
of photospheric motions using local correlation techniques (LCT). The
accuracy of these LCT's has been verified by comparison with La Palma
ground based data using other data sets (Shine, et al, 1997, B.A.A.S.,
29, 02.62). Horizontal divergence maps constructed from the flow maps
show local maxima of about the size of mesogranules. We interpret
these as mesogranules although the LCT flow map resolution (4.8 arc
seconds FWHM) may not completely resolve all mesogranules. Movies
made from the divergence maps clearly show the outward convection of
these "mesogranules" within each supergranule and narrow boundaries
of negative divergence outlining the supergranules. Several new
supergranules are observed forming as areas of strong divergence
that pop up between pre-existing supergranules and grow, pushing their
neighbors apart. Others seem to perish between growing neighbors. Movies
of the derived vertical curl do not show any obvious patterns. Videos
of these movies and the continuum, dopplergram, and magnetogram images
will be shown. This work was supported by NASA Grant NAG5-3077 at
Stanford and Lockheed Martin.
Title: Measurements of Solar Magnetic Element Dispersal
Authors: Berger, Thomas E.; Löfdahl, Mats G.; Shine, Richard A.;
Title, Alan M.
Bibcode: 1998ApJ...506..439B
Altcode:
The dispersal of magnetic elements in the solar photospheric flow
field is studied by tracking individual ``magnetic bright points''
(MBPs) identified in a G-band 4305 Å filtergram time series obtained
at the 50 cm Swedish Vacuum Solar Telescope on La Palma, Spain. The time
series spans approximately 70 minutes with a field of view of 29" × 29"
near disk center. All images in the time series are restored to near
the telescope diffraction limit (~0.2" in the G band) using partitioned
phase diverse speckle techniques. Regions of enhanced magnetic network
and quiet Sun are examined. In the network region, automated tracking
of individual MBPs reveals approximately Gaussian diffusion, with
indications for slightly ``superdiffusive'' dispersal. The inferred
Gaussian diffusion coefficient is 60.4 +/- 10.9 km2
s-1. In the quiet-Sun region, local correlation tracking
velocity measurements show the dispersal of artificial tracers to be
non-Gaussian over most of our data set with indications of an asymptotic
approach to a 285 km2 s-1 Gaussian diffusion.
Title: Large-scale coronal heating by the small-scale magnetic field
of the Sun
Authors: Schrijver, C. J.; Title, A. M.; Harvey, K. L.; Sheeley,
N. R.; Wang, Y. -M.; van den Oord, G. H. J.; Shine, R. A.; Tarbell,
T. D.; Hurlburt, N. E.
Bibcode: 1998Natur.394..152S
Altcode:
Magnetic fields play a crucial role in heating the outer atmospheres
of the Sun and Sun-like stars, but the mechanisms by which magnetic
energy in the photosphere is converted to thermal energy in the corona
remain unclear. Observations show that magnetic fields emerge onto
the solar surface as bipolar regions with a broad range of length
scales. On large scales, the bipolar regions survive for months before
dispersing diffusively. On the smaller scales, individual bipolar
regions disappear within days but are continuously replenished by new
small flux concentrations, resulting in a sustained state of mixed
polarity. Here we determine the rate of emergence of these small
bipolar regions and we argue that the frequent magnetic reconnections
associated with these regions (an unavoidable consequence of continued
flux replacement) will heat the solar atmosphere. The model that
describes the details of these mixed-polarity regions is complementary
to the traditional diffusion model for large-scale flux dispersal and
a combination of the two should lead to a more complete understanding
of the role of magnetic fields in stellar atmospheres.
Title: First Results from the TRACE Mission
Authors: Title, A.; Tarbell, T.; Schrijver, C.; Wolfson, J.; Shine,
R.; Hurlburt, N.; Golub, L.; Deluca, E.; Bookbinder, J.; Handy, B.;
Acton, L.; Harrison, R.; Delaboudinere, J. -P.
Bibcode: 1998AAS...192.1507T
Altcode: 1998BAAS...30..841T
The TRACE spacecraft was launched on 1 April and all systems are
functioning as designed. The initial outgassing period will conclude
on 20 April and the science program will then begin. TRACE is a UV-EUV
imager with one arc second spatial resolution and is capable of taking
images with a cadence as high as two seconds. We will present images
and image sequences. We hope to present initial comparisons of magnetic
evolution and transition region and coronal brightenings.
Title: The Postflare Loops and the Nearby Active Chromosphere of
1992 June 26: Addendum
Authors: Malherbe, J. -M.; Tarbell, T.; Wiik, J. E.; Schmieder, B.;
Frank, Z.; Shine, R. A.; van Driel-Gesztelyi, L.
Bibcode: 1998ApJ...495..502M
Altcode:
Video segments are presented that were processed from a quantitative
study of the dynamics of the evolution of Hα postflare loops developed
after a large solar flare. The high spatial resolution of the Swedish
Vacuum Solar Telescope (SVST) at La Palma provided a unique set of
data for such an event.
Title: Small-scale topology of solar atmosphere dynamics. I. Wave
sources and wave diffraction
Authors: Hoekzema, N. M.; Rutten, R. J.; Brandt, P. N.; Shine, R. A.
Bibcode: 1998A&A...329..276H
Altcode:
We study the small-scale topology of dynamical phenomena in the
quiet-sun internetwork atmosphere, using short-duration Fourier analysis
of high-resolution filtergram sequences to obtain statistical estimates
for the co-location probability of different fine-structure elements
and wave modes. In this initial paper we concentrate on the topology
of short-duration Fourier amplitude maps for the photosphere and the
simultaneously observed overlying chromosphere. We find that these
maps portray a complex mix of global modes and locally excited waves
which necessitates a statistical approach. Various aspects including
mesoscale patterning indicate the presence of subsurface wave sources
and of subsurface wave diffraction by convective inhomogeneities.
Title: A Possible Mechanism for the Origin of Emerging Flux in the
Sunspot Moat
Authors: Ryutova, M.; Shine, R.; Title, A.; Sakai, J. I.
Bibcode: 1998ApJ...492..402R
Altcode:
Mass and energy flow near sunspots are associated with the emergence
of magnetic flux, which then moves outward in the sunspot moat. We
present results of analytical and numerical studies of the interaction
of horizontal magnetic flux and plasma flows in three-dimensional
geometry. We show that nonlinear coupling of flux and plasma flows in
the presence of a gravitational field lead to nonlinear dissipative
instabilities that result in the formation of a solitary kink along
the magnetic flux. The stability of a kink and its further evolution
depend on the physical parameters of magnetic flux and the surrounding
medium. We discuss two major cases--magnetic soliton-like and shocklike
propagation along the magnetic flux--and specify the appropriate
physical conditions for their realization. In photospheric conditions,
the proposed mechanism may be a good candidate for understanding of
the dynamics of small-scale magnetic flux in the enhanced network at
the solar surface. We apply our results to the observed properties
of emerging flux in the sunspot region associated with moving magnetic
features and find reasonable qualitative and quantitative agreement.
Title: Photospheric flows as measured by SOI/MDI
Authors: Hurlburt, N.; Frank, Z.; Shine, R.; Tarbell, T.; Title, A.;
Simon, G.
Bibcode: 1997ASSL..225..285H
Altcode: 1997scor.proc..285H
On 2 February and 7 March 1996, MDI on the SOHO spacecraft ran several
hours to provide high resolution continuum images to map the horizontal
flows near the equator and pole by correlation tracking. Here we present
preliminary results on the performance of the tracking technique
in measuring the differential rotation profile. These preliminary
results are compared with each other and with corresponding results
of previous studies.
Title: Modeling the distribution of magnetic fluxes in field
concentrations in a solar active region
Authors: Schrijver, Carolus J.; Title, Alan M.; Hagenaar, Hermance J.;
Shine, Richard A.
Bibcode: 1997SoPh..175..329S
Altcode:
Much of the magnetic field in solar and stellar photospheres is
arranged into clusters of `flux tubes', i.e., clustered into compact
areas in which the intrinsic field strength is approximately a
kilogauss. The flux concentrations are constantly evolving as they
merge with or annihilate against other concentrations, or fragment
into smaller concentrations. These processes result in the formation
of concentrations containing widely different fluxes. Schrijver et
al. (1997, Paper I) developed a statistical model for this distribution
of fluxes, and tested it on data for the quiet Sun. In this paper we
apply that model to a magnetic plage with an average absolute flux
density that is 25 times higher than that of the quiet network studied
in Paper I. The model result matches the observed distribution for the
plage region quite accurately. The model parameter that determines the
functional form of the distribution is the ratio of the fragmentation
and collision parameters. We conclude that this ratio is the same in the
magnetic plage and in quiet network. We discuss the implications of this
for (near-)surface convection, and the applicability of the model to
stars other than the Sun and as input to the study of coronal heating.
Title: Sustaining the Quiet Photospheric Network: The Balance of
Flux Emergence, Fragmentation, Merging, and Cancellation
Authors: Schrijver, Carolus J.; Title, Alan M.; van Ballegooijen,
Adriaan A.; Hagenaar, Hermance J.; Shine, Richard A.
Bibcode: 1997ApJ...487..424S
Altcode:
The magnetic field in the solar photosphere evolves as flux
concentrations fragment in response to sheared flows, merge when they
collide with others of equal polarity, or (partially) cancel against
concentrations of opposite polarity. Newly emerging flux replaces the
canceled flux. We present a quantitative statistical model that is
consistent with the histogram of fluxes contained in concentrations
of magnetic flux in the quiet network for fluxes exceeding ~2 ×
1018 Mx, as well as with estimated collision frequencies
and fragmentation rates. This model holds for any region with weak
gradients in the magnetic flux density at scales of more than a few
supergranules. We discuss the role of this dynamic flux balance (i)
in the dispersal of flux in the photosphere, (ii) in sustaining the
network-like pattern and mixed-polarity character of the network, (iii)
in the formation of unipolar areas covering the polar caps, and (iv) on
the potential formation of large numbers of very small concentrations
by incomplete cancellation. Based on the model, we estimate that as
much flux is cancelled as is present in quiet-network elements with
fluxes exceeding ~2 × 1018 Mx in 1.5 to 3 days, which is
compatible with earlier observational estimates. This timescale is
close to the timescale for flux replacement by emergence in ephemeral
regions, so that this appears to be the most important source of flux
for the quiet-Sun network; based on the model, we cannot put significant
constraints on the amount of flux that is injected on scales that are
substantially smaller than that of the ephemeral regions. We establish
that ephemeral regions originate in the convection zone and are not
merely the result of the reemergence of previously cancelled network
flux. We also point out that the quiet, mixed-polarity network is
generated locally and that only any relatively small polarity excess
is the result of flux dispersal from active regions.
Title: The Postflare Loops and the Nearby Active Chromosphere of
1992 June 26
Authors: Malherbe, J. -M.; Tarbell, T.; Wiik, J. E.; Schmieder, B.;
Frank, Z.; Shine, R. A.; van Driel-Gesztelyi, L.
Bibcode: 1997ApJ...482..535M
Altcode:
The main objective of this paper is to present a quantitative study
of the dynamics of the evolution of Hα postflare loops developed
after a large solar flare and the processed videos produced from the
observations. The high spatial resolution of the Swedish Vacuum Solar
Telescope (SVST) at La Palma has provided a unique set of data for such
an event. A Gaussian fitting method is proposed to derive intensities
and Doppler shifts from observations taken at three wavelengths (Hα
center and Hα +/- 0.07 nm). Moving condensations or ``blobs'' of cold
material provide transverse velocities, which, together with the radial
component, enable us to derive their velocity vector magnitude. Plasma
velocities are around free-fall velocities near the top of the loops
but are significantly smaller close to their footpoints, suggesting
a deceleration mechanism. The loops are anchored in the chromosphere,
which shows tremendous activity in the active region and in the nearby
``quiet Sun.'' Spicules and ejection of plasmoids are also observed
at the limb.
Title: On the Dynamics of Magnetic Flux Concentrations in Quiet
Photospheric Network.
Authors: Sakai, J. I.; Ryutova, M.; Schrijver, K.; Shine, R.; Tarbell,
T.; Berger, T.; Title, A.; Hagenaar, H.
Bibcode: 1997SPD....28.0260S
Altcode: 1997BAAS...29..904S
Magnetic flux concentrations in the quiet photospheric network show
a complex dynamics which includes merging of colliding fluxes, the
"total" or partial cancellation of neighboring fluxes, fragmentation
and others. We propose a mechanism to explain the observed phenomena
based on the idea that magnetic flux concentrations in the photospheric
network are essentially non-collinear. We show that non-collinearity
of colliding fluxes leads to the whole new class of effects which are
observed; for example, the apparent cancellation of opposite polarity
fluxes turns into the formation of horizontal magnetic fluxes (which
later may appear as a new weaker bipoles) and is accompanied by the
shock formation and mini-flares. In the case of shock formation
the reconnection area becomes a source of the acoustic emission;
mini-flares may be seen as bright points. The energetics of these
processes strongly depends on geometry of "collision" and physical
parameters of colliding fluxes. For example, if colliding fluxes have
comparable and "small" cross sections, the reconnection results in
complete reorganization of their magnetic fields; if merging fluxes
are large enough or considerably different, magnetic flux may be
only partially reconnected and partially survived. Reconnection of
non-collinear equal polarity fluxes leads to the "scattering" processes
which include the fragmentation into several smaller fluxes if initially
colliding concentrations carried different amount of magnetic flux. We
give the example of numerical simulation for the case of merging and
fragmentation process occurring during the collision of collinear
"strong" and "weak" magnetic flux concentrations. The calculation
results shown to be consistent with observational data from both
the SOHO/MDI instrument and the Swedish Vacuum Solar Telescope on
La Palma. This research is supported by NASA contract NAG5-3077 at
Stanford University and the MDI contract PR 9162 at Lockheed.
Title: Nobeyama/SOHO/BBSO Comparison of Solar Polar Coronal Holes
Authors: Gary, D. E.; Enome, S.; Shibasaki, K.; Gurman, J. B.; Shine,
R. A.
Bibcode: 1997SPD....28.0801G
Altcode: 1997BAAS...29..912G
Although it is not widely known outside the discipline of solar
radiophysics, a long-standing puzzle exists: the poles of the Sun
appear brighter than the rest of the quiet Sun in a restricted range
of wavelengths roughly from 15 GHz to about 48 GHz (cf. Kosugi et
al. 1986). At somewhat lower radio frequencies the poles appear darker
than the quiet Sun due to a deficit of coronal material, while at
mm-wavelengths the polar and non-polar quiet Sun appear quite uniform
due to the similarity of the atmospheric structure at lower heights
in the chromosphere. The excess brightness at the poles has also been
reported in coronal holes on the disk, and so is apparently related to
the phenomenon of coronal holes. The brightening likely corresponds to
an elevated temperature in the upper chromosphere in coronal holes
relative to normal quiet Sun. The phenomenon is especially well
suited to study via radio emission due to the unique sensitivity of
radio waves to this height range in the chromosphere. The possibility
exists that the different chromospheric structure for coronal holes
implied by the radio brightening may offer some clue to the origin of
the fast solar wind, which is now well established to arise in coronal
holes. Radio brightening of coronal holes is a difficult observational
problem because an instrument is needed that can image large areas of
the Sun at relatively high resolution. The Nobeyama Radioheliograph
has the required capability and operates at 17 and 34 GHz, nicely
within the frequency range where the brightening occurs. We compare
Nobeyama radio synthesis images on several days in 1996 with images
from the EIT, CDS, and MDI experiments on the Solar and Heliospheric
Observatory (SOHO) spacecraft, and with high resolution images from
the Big Bear Solar Observatory, with the aim of determining the spatial
and temporal characteristics of the brightening. We compare the extent
of the radio brightening with the boundaries of the coronal holes seen
from the SOHO data, to establish the previously suggested identity of
the polar brightening with coronal holes. We investigate whether the
brightening is primarily associated with network features, faculae,
or perhaps bipolar magnetic elements, or whether it is instead a
diffuse brightening more-or-less uniformly covering the coronal hole
area. We look for temporal variations, and their correlation with
changing features seen from SOHO. We conclude with some ideas for how
the chromospheric structure may be different in coronal holes than in
normal quiet Sun, and speculate on the implications for acceleration
of the fast solar wind.
Title: Phase-Diversity Restoration of two Simultaneous 70-minute
Photospheric Sequences.
Authors: Lofdahl, M. G.; Berger, T. E.; Shine, R. A.; Title, A. M.
Bibcode: 1997SPD....28.0218L
Altcode: 1997BAAS...29..896L
Seeing effects have been corrected in two cospatial and cotemporal
70-minute sequences of images collected in the G-band 4305 Angstroms and
wideband 4686 Angstroms. The data were obtained with the 50 cm Swedish
Vacuum Solar Telescope on the island of La Palma, Spain. The 29arcsecx
70arcsec field-of-view (FOV) near disk center contains both an enhanced
network region and an (apparently) non-magnetic ``quiet'' region of
granulation. The mean time between restored frames is 23.5 s. Each of
the 180 images is created with Phase-Diverse Speckle (PDS) imaging,
using two different focus positions sampled at the best three snapshots
of the atmospheric turbulence (seeing) during a 20-second selection
window. Wavefronts are estimated for each focused--defocused image
pair and a restored frame is produced from all six images. The average
resolution in the restored sequence is about 0farcs4 (corresponding to
spatial frequencies up to half the diffraction limit of the telescope),
which is good enough to allow detection of ~ 0farcs2 bright points. The
data is used for statistical measurements of magnetic element speed,
interaction frequency, and lifetime (see accompanying poster by
T. E. Berger et al). We show destretched and space-time filtered
movies of both the G-band and continuum images, as well as raw data
to demonstrate the effect of the restoration process. This work was
supported by NASA contracts NAS5-30386 at Stanford and NAS8-39747 and
Independent Research Funds at Lockheed-Martin. MGL was supported by
the Swedish Science Research Council.
Title: Comparison of Granulation Correlation Tracking (CT) and
Feature Tracking (FT) Results from SOHO/MDI and the Swedish Vacuum
Solar Telescope on La Palma
Authors: Shine, R.; Strous, L.; Simon, G.; Berger, T.; Hurlburt, N.;
Tarbell, T.; Title, A.; Scharmer, G.
Bibcode: 1997SPD....28.0262S
Altcode: 1997BAAS...29Q.904S
We have computed photospheric velocity flow maps from simultaneous
observations taken with MDI and at the Swedish Vacuum Solar Tower
(SVST) on La Palma on August 15, 1996. Both sets consist of a series
of photospheric images, and flow maps are computed by following the
local motions of granules. The MDI data have the important advantages
of very stable images and longer continuous coverage of the same area
of the solar surface. This longer coverage is necessary to study the
evolution of mesogranules, supergranules, and to detect possible low
amplitude motions on scales larger than supergranules. However, the
high resolution mode of MDI is limited by the small telescope size to
about 1.2 arc seconds angular resolution and uses a 0.6 arc second pixel
size. This is adequate to show granulation but has the rms constrast
significantly reduced to about 2%. Early efforts adapting techniques
that were successful with higher resolution ground based images gave
poor results and although new methods have now been developed, there
are still some problems with accuracy. On the other hand, the SVST
images have much higher angular resolution (as good as 0.2 arc second)
but suffer from variable atmospheric distortion. They also have a much
smaller field of view. By detailed comparison of the two data sets
and by using CT and FT techniques to track the motions, we hope to
understand the sources of any differences between them and to develop
credible correction parameters to the MDI data sets if necessary. This
work was supported by NASA Grant NAG5-3077 at Stanford and Lockheed
Martin, by AFOSR and the Fellows Program of AF Phillips Lab at NSO/SP,
and by the Swedish Royal Academy of Sciences.
Title: Horizontal Velocity Structure of Supergranules near Disk
Center from High-Resolution SoHO/MDI Observations
Authors: Strous, L. H.; Simon, G. W.; Shine, R. A.; Hurlburt, N.
Bibcode: 1997SPD....28.0265S
Altcode: 1997BAAS...29S.904S
We determine the average surface flows in supergranules from
high-resolution SoHO/MDI observations near disk center, using local
correlation and feature tracking methods. We present results as a
function of distance to the supergranule center and of supergranule
size, and as a function of normalized distance to the supergranule
center. This work was supported by NASA Grant NAG5-3077 at Stanford and
Lockheed Martin, and by AFOSR and the Fellows Program of AF Phillips
Lab at NSO/SP.
Title: A search for interaction between magnetic fields and
supergranular flows in the network based on MDI observations
Authors: Schrijver, C. J.; Shine, R. A.; Title, A. M.; Hagenaar,
H. J.; Hurlburt, N. E.; Tarbell, T. D.; Simon, G. W.
Bibcode: 1997SPD....28.0243S
Altcode: 1997BAAS...29..901S
We study the supergranular flow field and its temporal evolution in
the quiet Sun as observed with the Michelson Doppler Imager on board
SOHO. We use the intensity images to derive the flow fields using
local correlation tracking. The data sets span one to two days with a
one--minute cadence. We separate areas with a relatively high filling
factor for magnetic concentrations from areas with a low magnetic
filling factor in order to study to what extent the flows influence
the magnetic network in the quiet Sun and vice versa. This work is
supported by NASA Grant NAG5-3077 at Stanford and Lockheed Martin,
and by AFOSR and the Fellows Program of AF Phillips Lab at NSO/SP
Title: Continuous Observations of Solar Magnetic Fields from SOI/MDI
on SOHO
Authors: Hoeksema, J. T.; Bush, R. I.; Scherrer, P. H.; Heck, C.;
Hurlburt, N.; Shine, R.; Tarbell, T.; Title, A.
Bibcode: 1997SPD....28.0127H
Altcode: 1997BAAS...29..884H
The Solar Oscillations Investigation's Michelson Doppler Imager
instrument (SOI/MDI) on SOHO measures the photospheric magnetic field
over the whole disk nearly every 96 minutes with 4" resolution and a
noise level of a few Gauss. Beginning in April 1996, this unprecedented
continuous series of frequent, uniform quality magnetograms provides
a striking view of the continual emergence, motion, evolution, and
interaction of magnetic flux everywhere on the visible solar surface
near solar minimum. These evolving photospheric fields ultimately
drive the variations of the corona and solar wind that affect the
terrestrial environment. Knowledge of the rapidly evolving photospheric
field provides a crucial input for forecasting conditions in the
corona, heliosphere, and geospace. A few magnetograms are available
each day within hours of observation through the SOHO web site at
http://sohowww.nascom.nasa.gov/. These may be used for planning and
forecasting, e.g. to compute models of the solar corona. The remainder
are generally available within a few weeks. Sometimes more focused
campaigns provide magnetic observations as often as once each minute
for up to 8 hours. Campaigns can be run with either the full disk
resolution or with 0.6" pixels in a limited field near the center of
the disk. The SOI project welcomes collaborations. More information
can be found at http://soi.stanford.edu/.
Title: Image Improvement Techniques
Authors: Shine, R. A.
Bibcode: 1997SPD....28.1202S
Altcode: 1997BAAS...29..916S
Over the last decade, a repertoire of techniques have been developed
and/or refined to improve the quality of high spatial resolution solar
movies taken from ground based observatories. These include real time
image motion corrections, frame selection, phase diversity measurements
of the wavefront, and extensive post processing to partially remove
atmospheric distortion. Their practical application has been made
possible by the increasing availability and decreasing cost of large
CCD's with fast digital readouts and high speed computer workstations
with large memories. Most successful have been broad band (0.3 to
10 nm) filtergram movies which can use exposure times of 10 to 30
ms, short enough to ``freeze'' atmospheric motions. Even so, only a
handful of movies with excellent image quality for more than a hour
have been obtained to date. Narrowband filtergrams (about 0.01 nm),
such as those required for constructing magnetograms and Dopplergrams,
have been more challenging although some single images approach the
quality of the best continuum images. Some promising new techniques and
instruments, together with persistence and good luck, should continue
the progress made in the last several years.
Title: Measurements of Magnetic Element Dynamics in the Network
Authors: Berger, T. E.; Lofdahl, M. G.; Shine, R. A.; Title, A. M.
Bibcode: 1997SPD....28.0219B
Altcode: 1997BAAS...29..896B
Statistical measurements of magnetic element speed, interaction
frequency, and lifetime in an enhanced network region at disk center
are presented. The primary dataset is a 70 min time series of G-band
4305 Angstroms filtergrams taken at the 50 cm Swedish Vacuum Solar
Telescope (SVST) on the island of La Palma, Spain. A second time
series of 4686 Angstroms wide-band continuum filtergrams, cospatial
and simultaneous to within several milliseconds with the G-band
images, is also studied. The field-of-view is near Sun center and
includes a region of enhanced network activity with many G-band bright
points. Both time series are corrected for seeing to very near the
telescope diffraction limit by the technique of Phase Diverse Speckle
(PDS) restoration (see accompanying poster by M. G. Lofdahl et al). We
show destretched and space-time filtered movies of both the G-band and
continuum images in two fields-of-view: a region of quiet granulation
and the region of enhanced network activity. Within the network, local
correlation tracking measurements on a 0\farcs4 grid show the RMS
speed to be 778 m s(-1) ; outside the network the RMS speed is 1168 m
s(-1) . Corkflow simulations show that normal convective flow patterns
(granulation and mesogranulation) are absent in the network. Magnetic
elements move with modal and mean speeds of 100 m s(-1) and 815 m s(-1)
, respectively. The mean interaction frequency (time between either
merging or splitting) is 220 s. The mean lifetime of tracked magnetic
elements in the network is 9.33 min although 5% of the elements are
tracked for the entire 70 min of the times series. This work was
supported by NASA contracts NAS5-30386 at Stanford and NAS8-39747 and
Independent Research Funds at Lockheed-Martin. MGL was supported by
the Swedish Science Research Council.
Title: Dispersal of magnetic flux in the quiet network as observed
on a day-long magnetogram sequences observed with MDI on SOHO
Authors: Hagenaar, H. J.; Schrijver, C. J.; Shine, R. A.; Title, A. M.
Bibcode: 1997SPD....28.0244H
Altcode: 1997BAAS...29..901H
We study the dynamic behavior of magnetic flux elements in the quiet
solar network using high--resolution magnetograms observed with the
Michelson Doppler Imager on board SOHO. We track concentrations of
magnetic flux in uninterrupted time sequences spanning 20 to 45 hours
in order to study the dispersal of magnetic elements in the turbulent
photospheric flows. We measure the displacements and derive average
speeds as a function of time. The displacements are compared to a
random walk model. This work is supported by NASA Grant NAG5-3077 at
Stanford and Lockheed.
Title: The TRACE Mission
Authors: Wolfson, J.; Bruner, M.; Jurcevich, B.; Lemen, J.; Schrijver,
K.; Shine, R.; Strong, K.; Tarbell, T.; Title, A.; Golub, L.;
Bookbinder, J.; Deluca, E.; Acton, L.; Handy, B.; Kankelborg, C.;
Fisher, R.
Bibcode: 1997SPD....28.0143W
Altcode: 1997BAAS...29..887W
The TRACE (Transition Region and Coronal Explorer) mission will explore
the connections between fine-scale magnetic fields and plasma structures
in the coronal, transition zone and temperature minimum regions of the
sun. TRACE will collect images of solar plasmas at temperatures from
10(4) to 10(7) K, with one arc second spatial resolution and excellent
temporal resolution and continuity. With a scheduled launch date of 15
December 1997, the mission will emphasize collaborative observations
with SoHO, enabling simultaneous observations of high-resolution images,
spectra, and magnetograms. The 30 cm aperture TRACE telescope uses four
normal-incidence coatings for the EUV and UV on quadrants of the primary
and secondary mirrors. Interference filters further isolate 5 different
UV bands. The images are co-aligned and internally stabilized against
spacecraft jitter. A 1024 x 1024 lumigen-coated CCD detector collects
images over an 8.5 x 8.5 arc minute field-of-view. LMATC, SAO, and GSFC
built the TRACE instrument, which was integrated with the GSFC-produced
SMEX spacecraft on 28 February (just over two years from the start
of its development). It will be put into a Sun-synchronous orbit and
operated in coordination with the SoHO Experiment Operations Facility at
GSFC. We are committed to maintaining a publicly accessible data base
for TRACE data. Browsing and data set requesting capabilities will be
provided at Web site www.space.lockheed.com/TRACE/TRACElinks.html. This
site already contains a large volume of information on the mission
including preliminary scientific observing programs and directions
as to how to participate in the mission now and in the future. This
project is supported by NASA contract NAS5-38099.
Title: Comparison of supergranular flows from doppler and local
correlation tracking velocities
Authors: Frank, Z.; Hurlburt, N.; Shine, R.; Tarbell, T.; Simon, G.;
Strous, L.; Matt, S.
Bibcode: 1997SPD....28.0259F
Altcode: 1997BAAS...29..903F
Measurements of the flows in the solar photosphere rely upon two
techniques: doppler measurements of the line-of-sight velocity
or tracking of features or patterns moving perpendicular to the
line-of-sight. These methods have differing characteristics. Doppler
measurements can easily measure surface flows near the limb
which are not seriously contaminated by p-modes or other solar
sources. However, they require excellent instrument calibration over
the full field of view. Even then vertical flows within supergranules
are barely detectable. Correlation and feature tracking have proven
useful for estimating transverse velocity using granules and other
tracers. Nevertheless, they can be degraded by the intensity variations
of p-modes and possibly other oscillatory motions, as well as by effects
of limb darkening and foreshortening. The two methods would both be
strengthened through detailed comparisons. Data collected by MDI/SOHO is
ideal for this purpose. The data is co-spatial and co-temporal, and is
all obtained through the same instrument. We compare Doppler velocities
with those obtained through correlation tracking using high-resolution
MDI/SOHO images. We focus on motions at positions exceeding 30 degrees
from disk center. After taking projection effects into account, we
combine the two measurements to form a three-dimensional picture of
the flows in the average supergranule. This work was supported by NASA
Grant NAG5-3077 at Stanford and Lockheed Martin, and by AFOSR and the
Fellows Program of AF Phillips Lab at NSO/SP.
Title: The dynamic nature of the supergranular network
Authors: Title, A. M.; Schrijver, C. J.; van Ballegooijen, A. A.;
Hagenaar, H. J.; Shine, R. A.
Bibcode: 1997SPD....28.0242T
Altcode: 1997BAAS...29..900T
The magnetic field in the quiet solar photosphere evolves as flux
concentrations fragment in response to sheared flows, merge when they
collide with others of equal polarity, or (partially) cancel against
concentrations of opposite polarity. Newly emerging flux, mostly in
ephemeral regions, replaces the canceled flux in a matter of a few
days. We present a quantitative statistical model to describe the
resulting histogram of fluxes contained in concentrations of magnetic
flux in the quiet network. We discuss this dynamic flux balance with
respect to (i) the potential dispersal of flux in the photosphere
as a function of ephemeral-region properties, (ii) sustaining the
network--like pattern and mixed--polarity character of the network,
and (iii) the formation of unipolar areas covering the polar caps. We
establish that ephemeral regions are not the result of the re-emergence
of previously cancelled network flux. Moreover, their emergence cannot
be correlated to the emergence of active regions but must instead
be relatively homogeneous. We also point out that the bulk of the
quiet, mixed-polarity network is generated locally, and that only any
relatively small polarity excess is the result of flux dispersal from
active regions.
Title: Interactive interface for visualizing and analyzing
multispectral solar images
Authors: Hurlbert, Neal E.; Shine, Richard A.; Tarbell, Theodore D.
Bibcode: 1997SPIE.3017..165H
Altcode:
We present an interactive software tool for manipulating image data,
especially high resolution multi-spectral solar movies and images
from several different instruments. This tool contains procedures for
distortion removal for ground based solar movies, correlation tracking,
image alignments, data compression, 3D FOurier filtering, interactive
viewing of space/time slices in movies, and browsing through data
cubes. This is a compete public domain package based on X windows
and Unix which is currently running on Silicon Graphics and Digital
Equipment workstations. These software tools are freely available to
the international solar community. Many components are also applicable
to image an movie analysis in astrophysics, space physics, and earth
sciences. They are available with documentation via our web pages
under http://www.space.lockheed.com.
Title: On the dynamics of magnetic flux concentrations in quiet
photospheric network.
Authors: Sakai, J. I.; Ryutova, M.; Schrijver, K.; Shine, R. A.;
Tarbell, T. D.; Berger, T. E.; Title, A. M.; Hagenaar, H. J.
Bibcode: 1997BAAS...29T.904S
Altcode:
No abstract at ADS
Title: The Dynamic Quiet Solar Corona: 4 Days of Joint Observing
with MDI and EIT
Authors: Schrijver, C. J.; Shine, R. A.; Hurlburt, N. E.; Tarbell,
T. D.; Lemen, J. R.
Bibcode: 1997ESASP.404..669S
Altcode: 1997cswn.conf..669S
No abstract at ADS
Title: Dynamics of the Chromospheric Network: Mobility, Dispersal,
and Diffusion Coefficients
Authors: Schrijver, Carolus J.; Shine, Richard A.; Hagenaar, Hermance
J.; Hurlburt, Neal E.; Title, Alan M.; Strous, Louis H.; Jefferies,
Stuart M.; Jones, Andrew R.; Harvey, John W.; Duvall, Thomas L., Jr.
Bibcode: 1996ApJ...468..921S
Altcode:
Understanding the physics behind the dispersal of photo spheric magnetic
flux is crucial to studies of magnetoconvection, dynamos, and stellar
atmospheric activity. The rate of flux dispersal is often quantified by
a diffusion coefficient, D. Published values of D differ by more than a
factor of 2, which is more than the uncertainties allow. We propose that
the discrepancies between the published values for D are the result of
a correlation between the mobility and flux content of concentrations of
magnetic flux. This conclusion is based on measurements of displacement
velocities of Ca II K mottles using an uninterrupted 2 day sequence
of filtergrams obtained at the South Pole near cycle minimum. We
transform the Ca II K intensity to an equivalent magnetic flux density
through a power-law relationship defined by a comparison with a nearly
simultaneously observed magnetogram. One result is that, wherever the
network is clearly defined in the filtergrams, the displacement vectors
of the mottles are preferentially aligned with the network, suggesting
that network-aligned motions are more important to field dispersal than
deformation of the network pattern by cell evolution. The rms value
of the inferred velocities, R = <|v|2>½,
decreases with increasing flux, Φ, contained in the mottles, from R
≍ 240 m s-1 down to 140 s-1. The value of R(Φ)
appears to be independent of the flux surrounding the concentration,
to the extreme that it does not matter whether the concentration is
in a plage or in the network. The determination of a proper effective
diffusion coefficient requires that the function R(Φ) be weighted
by the number density n(Φ) of mottles that contain a total flux. We
find that n(Φ) decreases exponentially with Φ and propose a model
of continual random splitting and merging of concentrations of flux to
explain this dependence. Traditional methods used to measure D tend to
be biased toward the larger, more sluggish flux concentrations. Such
methods neglect or underestimate the significant effects of the
relatively large number of the more mobile, smaller concentrations. We
argue that the effective diffusion coefficient for the dispersal of
photo spheric magnetic flux is ∼600 km2 s-1.
Title: A Possible Mechanism for the Origin Emerging Flux in the
Sunspot Moat
Authors: Sakai, Jun-Ichi; Shine, R.; Title, A.; Ryutova, M.
Bibcode: 1996AAS...188.3502S
Altcode: 1996BAAS...28R.871S
Mass and energy flow near sunspots is associated with the emergence
of magnetic flux which then moves outward in the sunspot moat. We
present results of analytical and numerical studies of the interaction
of horizontal magnetic flux and plasma flows in 3D-geometry. We show
that nonlinear coupling of flux and plasma flows in the presence of
a gravitational field lead to nonlinear dissipative instabilities
which result in the formation of a solitary kink along the magnetic
flux. The stability of a kink and its further evolution depends on the
physical parameters of magnetic flux and surrounding medium. We discuss
two major cases, magnetic soliton- and shock-like propagation along
the magnetic flux, and specify the appropriate physical conditions for
their realization. For example, under conditions in a sunspot moat, when
the mass flow velocity exceeds about 0.5 v_A there occurs a magnetic
soliton-like kink, propagating with a velocity less than the external
mass flow velocity. The larger the radius of a flux tube, the larger the
``width'' of a soliton, and the lower the velocity of its propagation;
the width of a soliton corresponds to the separation of ``legs'' of a
kink which appear as magnetic field of the opposite polarities - the
nearest to sunspot has obviously the same polarity. When the external
mass flow velocity is less than about 0.5 v_A, a magnetic shock-like
perturbation can propagate with a velocity larger than the external
mass flow velocity. We apply these results to the observed properties
of emerging flux and find reasonable qualitative and quantitative
agreement. This research was supported by NASA contract NAG5-3077 at
Stanford University (M.R.) and NASA contract NAS8-39747 at
Title: Initial Results from SOI/MDI High Resolution Magnetograms
Authors: Title, A.; Tarbell, T.; Frank, Z.; Schrijver, C.; Shine,
R.; Wolfson, J.; Zayer, I.; Scherrer, P.; Bush, R.; Deforest, C.;
Hoeksema, T.
Bibcode: 1996AAS...188.6915T
Altcode: 1996BAAS...28..938T
The Michelson Doppler Imager (MDI) on SoHO takes magnetogram
s with resolutions of 1.2 (high resolution) and 4 (full disk)
arcseconds. Movies of 16 hour duration have been constructed in full
disk and high resolution mode. High resolution movies of the south
polar region also have been obtained. In sums of nine high resolution
magnetograms it is possible to detect fields as low as 5 gauss and
total fluxes as low as 5 10(1) 6 Mx. In mid latitude regions new flux
is observed to emerge everywhere. At all latitudes below 60 degrees
flux is mixed on the scale of supergranulation. In the polar region
above 60 degrees only fields of a single polarity are observed above
the detection limit.
Title: Preliminary SOI/MDI Observations of Surface Flows by
Correlation Tracking in the Quiet Solar Photosphere and an Emerging
Active Region
Authors: Tarbell, T.; Frank, Z.; Hurlburt, N.; Saba, J.; Schrijver,
C.; Shine, R.; Title, A.; Simon, G.; Strous, L.
Bibcode: 1996AAS...188.6914T
Altcode: 1996BAAS...28..937T
The extended observation of the solar surface with frequent sampling
provided by MDI on SoHO offers the chance to observe the evolution of
supergranules and to measure surface flows associated with active
regions and perhaps larger scale zonal and meridonal flows. We
have used local correlation tracking of the granulation pattern for
measuring surface flows from MDI high resolution continuum images. The
datasets consist of 1024 x 1024 pixel images collected with a cadence
of one minute and extending many hours each. The images are typically
centered upon the central meridian of the sun and offset to the north
of sun center, spanning roughly 40 degrees of solar longitude and from
approximately -10 to +30 degrees of solar latitude. The latitude
dependence of the differential rotation is evident. We present
preliminary results of our search for signatures of mesogranules,
supergranules and giant cells. On 23 Feb. 1996, we obtained a 12-hour
continuous sequence including quiet sun near disk center and NOAA
region 7946 at about N08 E30. The active region grew rapidly over this
interval, forming several sunpots. We show preliminary comparisons of
the measured flow fields with coaligned SOI/MDI magnetograms taken
at 15-minute intervals. The SOI/MDI program is supported by NASA
grant NAG5-3077.
Title: SOI/MDI Measurements of Horizontal Flows in the South Polar
Region of the Sun by Correlation Tracking and Doppler Shifts
Authors: Simon, G.; Frank, Z.; Hurlburt, N.; Schrijver, C.; Shine,
R.; Tarbell, T.; Title, A.; Deforest, C.
Bibcode: 1996AAS...188.6913S
Altcode: 1996BAAS...28R.937S
On 7 March 1996, the SOHO spacecraft was offset from its usual
disk center pointing for an 11-hour observation of the South
Polar region. MDI took a continuous time series of high resolution
longitudinal magnetograms during this period, in support of the
SOHO-wide Joint Observing Program on polar plumes. It also ran several
hours each of two other programs: one to map the horizontal flows near
the pole by correlation tracking and Doppler shifts, and another to
study wave propagation (e.g., by time-distance helioseismology) at
these high latitudes. In this poster we present preliminary results
from the first program. Both techniques yield measurements of the
differential rotation profile near the pole and of horizontal flows of
supergranulation. These results are compared with each other and with
corresponding measurements in low latitudes. The location of magnetic
features in the horizontal flows is also shown. The SOI/MDI program
is supported by NASA grant NAG5-3077.
Title: Photospheric Surface Flows and Small Magnetic Structures in
Sunspot Moats
Authors: Shine, R. A.; Title, A.; Frank, Zoe; Scharmer, G.
Bibcode: 1996AAS...188.3501S
Altcode: 1996BAAS...28Q.871S
We have computed horizontal flow maps of the photosphere around
and within three different sunspots using high spatial resolution
continuum movies obtained at the Swedish Vacuum Solar Telescope on
La Palma on June 5, 1993, August 29, 1993, and July 14, 1994. Two
of the data sets also included magnetograms and dopplergrams. A new
feature found in the flow maps is azimuthal structure in the moat
flows surrounding sunspots. Instead of a simple radial flow, there
are zones of azimuthal divergence and convergence resulting in radial
``spokes'' of convergence. These are not uniformly distinct around the
entire circumference but are seen in part of the surrounding area for
all 3 sunspots. The angular spacing is about 10 to 20 degrees and the
pattern persists for several hours. For one of the sunspots, we have
concurrent movies made with a 3 Angstrom wide K line filter. A time
average of these images shows bright spokes in the K line congruent with
the convergence spokes. Much of the magnetic flux that is continually
emerging and moving outward in the moat is in the vicinity of the
``spokes.'' In addition, these data show several good examples of
so called ``streakers.'' These are small bright structures seen in
continuum movies that appear to be emitted from the outer edge of the
penumbral and travel a few thousand km at about 2 to 3 km/s before
fading. We find that these are associated with a magnetic field of
opposite polarity to the sunspot and that they travel toward another
larger and slower moving magnetic feature with the same polarity as
the sunspot. When the streaker catches up, it disappears, sometimes
coincident with a brightening of the merged feature which continues
outward at the previous velocity, about 0.5 km/s. This work was
supported by NSF grant ATM-9213879, NASA contracts NAS8-39746 and
NAS8-39747, Lockheed Independent Research Funds, and the Swedish Royal
Academy of Sciences.
Title: Heating of Active Region Corona by Transient Brightenings
(Microflares)
Authors: Shimizu, T.; Tsuneta, T.; Title, A.; Tarbell, T.; Shine,
R.; Frank, Z.
Bibcode: 1996mpsa.conf...37S
Altcode: 1996IAUCo.153...37S
No abstract at ADS
Title: New Observations of Subarcsecond Photospheric Bright Points
Authors: Berger, T. E.; Schrijver, C. J.; Shine, R. A.; Tarbell,
T. D.; Title, A. M.; Scharmer, G.
Bibcode: 1995ApJ...454..531B
Altcode:
We have used an interference filter centered at 4305 Å within the
bandhead of the CH radical (the "G band") and real-time image selection
at the Swedish Vacuum Solar Telescope on La Palma to produce very
high contrast images of subarcsecond photospheric bright points at all
locations on the solar disk. During the 6 day period of 1993 September
15-20 we observed active region NOAA 7581 from its appearance on the
East limb to a near disk-center position on September 20. A total of
1804 bright points were selected for analysis from the disk center image
using feature extraction image processing techniques. The measured FWHM
distribution of the bright points in the image is subnormal with a modal
value of 220 km (0".30) and an average value of 250 km (0".35). The
smallest measured bright point diameter is 120 km (0".17) and the
largest is 600 km (0".69). Approximately 60% of the measured bright
points are circular (eccentricity ∼1.0), the average eccentricity
is 1.5, and the maximum eccentricity corresponding to filigree in
the image is 6.5. The peak contrast of the measured bright points is
normally distributed. The contrast distribution variance is much greater
than the measurement accuracy, indicating a large spread in intrinsic
bright-point contrast. When referenced to an averaged "quiet-Sun area 1n
the image, the modal contrast is 29% and the maximum value is 75%; when
referenced to an average intergranular lane brightness in the image,
the distribution has a modal value of 61 % and a maximum of 119%. The
bin-averaged contrast of G-band bright points is constant across the
entire measured size range. The measured area of the bright points,
corrected for population and selection effects, covers about 1.8% of
the total image area. Large pores and micropores occupy an additional
2% of the image area, implying a total area fraction of magnetic
proxy features in the image of 3.8%. We discuss the implications of
this area fraction measurement in the context of previously published
measurements which show that typical active region plage has a magnetic
filling factor on the order of 10% or greater. The results suggest that
in the active region analyzed here, less than 50% of the small-scale
magnetic flux tubes are demarcated by visible proxies such as bright
points or pores.
Title: Simulated MDI Observations of Convection
Authors: Hurlburt, N. E.; Schrijver, C. J.; Shine, R. A.; Title, A. M.
Bibcode: 1995ESASP.376b.239H
Altcode: 1995soho....2..239H; 1995help.confP.239H
No abstract at ADS
Title: Warning: Local Correlation Tracking may BE Dangerous to your
(scientific) Health
Authors: Simon, G. W.; Brandt, P. N.; November, L. J.; Shine, R. A.;
Strous, L. H.
Bibcode: 1995ESASP.376b.223S
Altcode: 1995soho....2..223S; 1995help.confP.223S
No abstract at ADS
Title: The Possible Ascent of a Closed Magnetic System through
the Photosphere
Authors: Lites, B. W.; Low, B. C.; Martinez Pillet, V.; Seagraves,
P.; Skumanich, A.; Frank, Z. A.; Shine, R. A.; Tsuneta, S.
Bibcode: 1995ApJ...446..877L
Altcode:
We present a comprehensive interpretation of the evolution of a small
magnetic region observed during its entire disk passage. The vector
magnetic field measurements from the Advanced Stokes Polarimeter,
along with Hα and magnetogram measurements from the Lockheed SOUP
instrument operating at the Swedish Solar Observatory on La Palma,
and soft X-ray images from the Yohkoh satellite support the hypothesis
that we have observed the passage of a nearly closed magnetic system
through the photosphere into the corona. The observations suggest that
as the magnetic flux begins to emerge into the photosphere it shows a
rather simple geometry, but it subsequently develops a small δ-sunspot
configuration with a highly sheared vector field along the polarity
inversion line running through it. At that stage, the vector field is
consistent with a concave upward magnetic topology, indicative of strong
electric currents above the photosphere. An Hα prominence is found
above this inversion line when the δ-sunspot is fully formed. These
observed features and the sequence of events are interpreted in terms
of a nearly closed magnetic system that rises through the photosphere
into the corona as a result of magnetic buoyancy. The magnetic system
persists in the corona well after the dark δ-sunspot has disappeared
in the photosphere We suggest that this coronal structure is in
quasi-static equilibrium with its buoyancy partially countered by
the weight of the plasma trapped at the bottom of closed magnetic
loops. The plausibility of such a scenario is demonstrated by a
three-dimensional magnetostatic model of the emergence of a closed,
spheroidal magnetic system in the corona, in which the Lorentz force
arising from cross-field currents is balanced by the gravitational
and pressure forces. This theoretical model carries many features in
common with the observed morphology of our active region.
Title: Frame Selection Techniques for Solar Movies
Authors: Shine, R. A.; Tarbell, T.; Title, A.; Scharmer, G.; Simon,
G.; Brandt, P.; Berger, T.
Bibcode: 1995SPD....26..506S
Altcode: 1995BAAS...27..957S
No abstract at ADS
Title: Flux Emergence in a Sunspot Moat and Young Active Region
Authors: Title, A. M.; Frank, Z. A.; Shine, R. A.; Tarbell, T. D.;
Simon, G. W.; Brandt, P. N.
Bibcode: 1995SPD....26.1007T
Altcode: 1995BAAS...27..978T
No abstract at ADS
Title: Properties of Sub-Arcsecond Facular Bright Points
Authors: Berger, T.; Schrijver, C.; Shine, R.; Tarbell, T.; Title,
A.; Scharmer, G.
Bibcode: 1995SPD....26..505B
Altcode: 1995BAAS...27..957B
No abstract at ADS
Title: Observations of Convection
Authors: Title, A. M.; Hurlburt, N.; Schrijver, C.; Shine, R.;
Tarbell, T.
Bibcode: 1995ESASP.376a.113T
Altcode: 1995heli.conf..113T; 1995soho....1..113T
The primary goal of the Solar Oscillations Investigation is
to understand the interior of the Sun using the techniques of
helioseismology. In addition the Michelson Doppler Imager produces
images of the solar surface with sufficient resolution to measure
surface flows via the technique of local correlation tracking and
magnetograms which allow feature tracking of magnetic fields. It will
be possible to measure the evolution of meso and supergranulation, the
evolution of the meso and supergranulation patterns, and the motion of
magnetic elements in the flow field. With observing periods of 8 hours
one should be able to detect large scale flow fields of 10 m/s second
or less. The magnetograms will provide the data to understand how the
cell patterns evolve as a function of magnetic field configuration.
Title: On the Relation Between Facular Bright Points and the
Magnetic Field
Authors: Berger, Thomas; Shine, Richard; Tarbell, Theodore; Title,
Alan; Scharmer, Goran
Bibcode: 1994AAS...185.8607B
Altcode: 1994BAAS...26.1465B
Multi-spectral images of magnetic structures in the solar photosphere
are presented. The images were obtained in the summers of 1993 and
1994 at the Swedish Solar Telescope on La Palma using the tunable
birefringent Solar Optical Universal Polarimeter (SOUP filter), a 10
Angstroms wide interference filter tuned to 4304 Angstroms in the band
head of the CH radical (the Fraunhofer G-band), and a 3 Angstroms wide
interference filter centered on the Ca II--K absorption line. Three
large format CCD cameras with shuttered exposures on the order of
10 msec and frame rates of up to 7 frames per second were used to
create time series of both quiet and active region evolution. The
full field--of--view is 60times 80 arcseconds (44times 58 Mm). With
the best seeing, structures as small as 0.22 arcseconds (160 km) in
diameter are clearly resolved. Post--processing of the images results
in rigid coalignment of the image sets to an accuracy comparable to the
spatial resolution. Facular bright points with mean diameters of 0.35
arcseconds (250 km) and elongated filaments with lengths on the order
of arcseconds (10(3) km) are imaged with contrast values of up to 60
% by the G--band filter. Overlay of these images on contemporal Fe I
6302 Angstroms magnetograms and Ca II K images reveals that the bright
points occur, without exception, on sites of magnetic flux through the
photosphere. However, instances of concentrated and diffuse magnetic
flux and Ca II K emission without associated bright points are common,
leading to the conclusion that the presence of magnetic flux is a
necessary but not sufficient condition for the occurence of resolvable
facular bright points. Comparison of the G--band and continuum images
shows a complex relation between structures in the two bandwidths:
bright points exceeding 350 km in extent correspond to distinct
bright structures in the continuum; smaller bright points show no
clear relation to continuum structures. Size and contrast statistical
cross--comparisons compiled from measurements of over two-thousand
bright point structures are presented. Preliminary analysis of the time
evolution of bright points in the G--band reveals that the dominant mode
of bright point evolution is fission of larger structures into smaller
ones and fusion of small structures into conglomerate structures. The
characteristic time scale for the fission/fusion process is on the
order of minutes.
Title: Flux Emergence in the Sunspot Moat
Authors: Title, A. M.; Shine, R. A.; Frank, Z. A.; Simon, G. W.;
Brandt, P. N.
Bibcode: 1994AAS...185.8602T
Altcode: 1994BAAS...26.1464T
On 13-15 June 1994 we obtained simultaneous movies of a sunspot in
NOAA active region 7731 through a 3 Angstroms band K line filter, the
LPARL tunable filter, and an 8 Angstroms G band filter. The data sets
allow us to make aligned magnetic, continuum, Doppler, K line, and
G band movies. The sunspot had a well developed moat. Flux emergence
occured throughout the moat. The initial signature of the emergence
was a transient dark elongated structure in the K line images that was
aligned radially with respect to the spot. Bright point pairs appeared
at the ends of these features in the K line and G band shortly after
their emergence. Magnetic field is observed cospatial with the K line
bright point pairs. The magnetic polarity of the end of the pair closest
to the spot is the same as the spot. The pairs of bright points move
across the moat in a radial direction away from the spot. When the
pairs reach the moat boundary the leading bright point merges with a
moat feature and the two disappear. The leading bright point's field
and the moat field cancel, since the moat boundary and the spot have
the same polarity. We believe that these features are different from
the long observed moving magnetic features associated with sunspots.
Title: High-Resolution Observations of the Evershed Effect in Sunspots
Authors: Shine, R. A.; Title, A. M.; Tarbell, T. D.; Smith, K.; Frank,
Z. A.; Scharmer, Goran
Bibcode: 1994ApJ...430..413S
Altcode:
High spatial resolution movies of sunspots taken at the Swedish
Solar Observatory on La Palma reveal that the Evershed effect is time
dependent. Outward proper motions are visible in both the continuum
and Dopplergrams. These can be tracked over most of the width of
the penumbra and overlap regions that show inward moving penubral
grains. The radial spacing between the moving structures is about 2000
km, and they exhibit irregular repetitive behavior with a typical
interval of 10 minutes. These are probably the cause of 10 minutes
oscillations sometimes seen in a penumbral power spectra. Higher
velocities are spatially correlated with the relatively darker regions
between bright filaments. Regions with a strong variation in the Doppler
signal show peak-to-peak modulations of 1 km/s on an average velocity
of about 3-4 km/s. The proper motion velocity is approximately constant
from the iner penumbra and generally larger than the Doppler velocity
when both are interpreted as projections of horizontal motion. Regions
where thay are consistent suggest a typical horizontal velocity of
3.5 km/s. Some proper motion velocites as high as 7 km/s are seen,
but these are less certain. The temporal behavoir shows a correlation
between increased Doppler signal and increased continuum intensity,
the opposite of the spatial correlation. When spatially averaged
across filaments and over time, the averaged Evershed effect has a peak
horizontal component near the outer edge of the penumbra of 2.0 km/s
with evidence for a 200-400 m/s upward component. The latter depends
on an uncertain absolute velocity calibration. If real it could be
an actual upward component or a penumbral analogue of the convective
blueshift seen in the quiet Sun.
Title: Observing Stellar Coronae with the Goddard High Resolution
Spectrograph. I. The dMe Star AU Microscopii
Authors: Maran, S. P.; Robinson, R. D.; Shore, S. N.; Brosius, J. W.;
Carpenter, K. G.; Woodgate, B. E.; Linsky, J. L.; Brown, A.; Byrne,
P. B.; Kundu, M. R.; White, S.; Brandt, J. C.; Shine, R. A.; Walter,
F. M.
Bibcode: 1994ApJ...421..800M
Altcode:
We report on an observation of AU Mic taken with the Goddard High
Resolution Spectrograph (GHRS) aboard the Hubble Space Telescope. The
data consist of a rapid sequence of spectra covering the wavelength
range 1345-1375 A with a spectral resolution of 10,000. The observations
were originally intended to search for spectral variations during
flares. No flares were detected during the 3.5 hr of monitoring. A
method of reducing the noise while combining the individual spectra
in the time series is described which resulted in the elimination of
half of the noise while rejecting only a small fraction of the stellar
signal. The resultant spectrum was of sufficient quality to allow the
detection of emission lines with an integrated flux of 10-15
ergs/sq cm(sec) or greater. Lines of C I, O I, O V, Cl I, and Fe XXI
were detected. This is the first indisputable detection of the 1354
A Fe XXI line, formed at T approximately = 107 K, on a
star other than the Sun. The line was well resolved and displayed
no significant bulk motions or profile asymmetry. From the upper
limit on the observed line width, we derive an upper limit of 38 km/s
for the turbulent velocity in the 107 K plasma. An upper
limit is derived for the flux of the 1349 A Fe XII line, formed at T
approximately = 1.3 x 106 K. These data are combined with
contemporaneous GHRS and International Ultraviolet Explorer (IUE) data
to derive the volume emission measure distribution of AU Mic over the
temperature range 104-107 K. Models of coronal
loops in hydrostatic equilibrium are consistent with the observed
volume emission measures of the coronal lines. The fraction of the
stellar surface covered by the footprints of the loops depends upon the
loop length and is less than 14% for lengths smaller than the stellar
radius. From the upper limit to the estimated width of the Fe XXI line
profile we find that the we cannot rule out Alfven wave dissipation
as a possible contributor to the required quiescent loop heating rate.
Title: Dynamics of the Evershed effect
Authors: Shine, R. A.; Title, A. M.; Tarbell, T. D.; Smith, K.; Frank,
Z. A.; Scharmer, G.
Bibcode: 1994ASIC..433..197S
Altcode:
No abstract at ADS
Title: On photospheric flows and chromospheric corks
Authors: Brandt, P. N.; Rutten, R. J.; Shine, R. A.; Trujillo Bueno, J.
Bibcode: 1994ASIC..433..251B
Altcode:
No abstract at ADS
Title: Vector-Stokes polarimetry in a sunspot
Authors: Hofmann, A.; Shine, R. A.; Frank, Z. A.; Schmidt, W.;
Balthasar, H.
Bibcode: 1994smf..conf..204H
Altcode:
No abstract at ADS
Title: High resolution vector polarimetry of sunspot magnetic fields.
Authors: Balthasar, H.; Hofmann, A.; Schmidt, W.; Shine, R. A.; Frank,
Z. A.
Bibcode: 1994AGAb...10..112B
Altcode:
No abstract at ADS
Title: Large-scale photospheric motions: first results from an
extraordinary eleven-hour granulation observation
Authors: Simon, G. W.; Brandt, P. N.; November, L. J.; Scharmer,
G. B.; Shine, R. A.
Bibcode: 1994ASIC..433..261S
Altcode:
No abstract at ADS
Title: High Resolution Observations of the Evershed Flow in Sunspots
Authors: Shine, R.; Title, A.; Smith, K.; Scharmer, G.
Bibcode: 1993BAAS...25.1183S
Altcode:
No abstract at ADS
Title: Multitemperature Observations of an Emerging Flux Region
Authors: Bruner, M. E.; Acton, L. W.; Brown, W. A.; Lemen, J. R.;
Shine, R.; Strong, K. T.; Tarbell, T.; Dulk, G.; Tsuneta, S.; Bastian,
T.; Dame, L.
Bibcode: 1993BAAS...25.1179B
Altcode:
No abstract at ADS
Title: Observations of an Emerging Flux Region
Authors: Brown, W. A.; Acton, L. W.; Bruner, M. E.; Lemen, J. R.;
Shine, R.; Strong, K. T.; Tarbell, T.; Dulk, G.; Tsuneta, S.; Bastian,
T.; Dame, L.
Bibcode: 1993BAAS...25Q1214B
Altcode:
No abstract at ADS
Title: Solar Coronal Magnetic Field Topology Inferred from High
Resolution Optical and X-ray Movies
Authors: Tarbell, T.; Frank, Z.; Hurlburt, N.; Morrison, M.; Shine,
R.; Title, A.; Acton, L.
Bibcode: 1993BAAS...25.1208T
Altcode:
No abstract at ADS
Title: La Palma Observations During the CoMStOC'92 Campaign
Authors: Shine, R.; Tarbell, T.; Topka, K.; Frank, Z.; Title, A.;
Scharmer, G.
Bibcode: 1993BAAS...25S1223S
Altcode:
No abstract at ADS
Title: ``The Active Sun'': Educational Videotapes on Solar Physics
for College Astronomy
Authors: Hurlburt, N.; Title, A.; Tarbell, T.; Frank, Z.; Topka, K.;
Shine, R.
Bibcode: 1993AAS...182.1002H
Altcode: 1993BAAS...25..809H
We present a series of short, educational documentaries on solar
physics aimed at college-level general astronomy courses. These
tapes highlight recent advances in high-resolution solar astronomy
and in theoretical and computational modeling of solar physics
with particular focus on dynamical phenomena. The relevant physical
mechanisms, theoretical interpretations and observational techniques
are discussed. These include granulation, the theory of convection,
five-minute oscillations, sunspots, magnetic fields, seeing and
dopplergrams. VHS tapes are available to researchers and educators
through a variety of distributors. This work supported by Lockheed
Independent Research Funds.
Title: Solar Coronal Magnetic Field Topology Inferred from High
Resolution Optical and X-ray Movies
Authors: Tarbell, T.; Frank, Z.; Hurlburt, N.; Morrison, M.; Shine,
R.; Title, A.; Acton, L.
Bibcode: 1993AAS...182.4805T
Altcode: 1993BAAS...25R.880T
We are using high resolution digital movies of solar active regions
in optical and X-ray wavelengths to study solar flares and other
transients. The optical movies were collected at the Swedish Solar
Observatory on La Palma using the Lockheed tunable filtergraph
system, in May - July, 1992. They include longitudinal and transverse
magnetograms, H-alpha Doppler and intensity images at many wavelengths,
Ca K, Na D, and white light images. Simultaneous X-ray images from
Yohkoh are available much of the time. We are learning several ways to
establish the connectivity of some coronal magnetic field lines. Some
of the clues available are: magnetic footpoint polarities and transverse
field directions; H-alpha fibrils and loops seen in several wavelengths;
proper motion and Doppler shifts of blobs moving along field lines;
footpoint brightening in micro-flares; spreading of flare ribbons
during gradual phases of flares; X-ray morphology and correlations with
H-alpha; and draining of flare loops. Examples of each of these will
be shown on video. This work is supported by NASA Contracts NASW-4612
and NAS8-37334 and by Lockheed Independent Research Funds.
Title: On the Magnetic and Velocity Field Geometry of Simple Sunspots
Authors: Title, Alan M.; Frank, Zoe A.; Shine, Richard A.; Tarbell,
Theodore D.; Topka, Kenneth P.; Scharmer, Goran; Schmidt, Wolfgang
Bibcode: 1993ApJ...403..780T
Altcode:
It is presently shown that a simple sunspot model with azimuthal
variations in inclination, but lacking azimuthal field-strength
variations, is free from azimuthal Lorentz forces. The meridional
currents arising from the inclination variations are parallel to the
field lines, suggesting that a cylindrically symmetric magnetostatic
sunspot model can be perturbed into one with azimuthal variations in
inclination with adjustment of the meridional force balance.
Title: White-light movies of the solar photosphere from the SOUP
instrument on Spacelab 2 (Advances in Space Research 1986)
Authors: Title, A. M.; Tarbell, T. D.; Simon, G. W.; Acton, L.;
Duncan, D.; Ferguson, S.; Finch, M.; Frank, Z.; Kelly, G.; Lindgren,
R.; Morrill, M.; Pope, T.; Reeves, R.; Rehse, R.; Shine, R.; Topka,
K.; Harvey, J.; Leibacher, J.; Livingston, W.; November, L.
Bibcode: 1993inas.book..100T
Altcode:
No abstract at ADS
Title: Data Compression Experiments with High Resolution Solar Images
Authors: Shine, R. A.; Majani, E. E.
Bibcode: 1992AAS...181.8113S
Altcode: 1992BAAS...24.1254S
No abstract at ADS
Title: High resolution observations: the state of the art and beyond.
Authors: Title, A.; Tarbell, T.; Shine, R.; Topka, K.; Frank, Z.
Bibcode: 1992ESASP.344....9T
Altcode: 1992spai.rept....9T
Excellent telescopes on excellent sites with fast digital CCD cameras
and special purpose computers allow the collection of broad band images
at just the instants of good seeing. This has resulted in nearly optimal
movies of the solar surface for several hours. When longer exposures
are required for narrowband filtergrams or spectra it is not enough to
capture single images. However, big fast memories allow the collection
of many selected low signal-to-noise ratio images in real time, which
can be summed to achieve the desired signal to noise ratios. Adaptive
optics shows promise of diffraction limited images for limited fields
of view. Nevertheless, groundbased observations will always be limited
in their duration, uniformity, and resolution qualities which are
essential for understanding the development and evolution of small scale
processes. Until there are observations in space we will not be able
to completely understand either the processes in the solar atmosphere
or how processes occurring at different height are interrelated.
Title: Evolution and advection of solar mesogranulation
Authors: Muller, Richard; Auffret, Herve; Roudier, Thierry; Vigneau,
Jean; Simon, George W.; Frank, Zoe; Shine, Richard A.; Title, Alan M.
Bibcode: 1992Natur.356..322M
Altcode:
GRANULAR structure on the Sun's surface, with a typical scale
of 1-2 Mm, has been known since 1800, and one hundred years ago,
with the first observations by spectroheliograph1,2,
a mesh-like bright network was found with a characteristic scale
of 30 Mm (40''). This pattern was found, thirty years ago, to be
coincident with close-packed convective cells ('supergranulation')
revealed by Doppler observations3-5 to be nestling inside
the bright network. More recently6,7 an intermediate
'mesogranular' structure was found, with a characteristic scale of
3-10 Mm. We have obtained a three-hour sequence of observations at
the Pic du Midi observatory which shows the evolution of mesogranules
from appearance to disappearance with unprecedented clarity. We see
that the supergranules, which are known to carry along (advect) the
granules with their convective motion, also advect the mesogranules to
their boundaries. This process controls the evolution and disappearance
of mesogranules.
Title: High Resolution Observations of the Magnetic and Velocity
Field of Simple Sunspots
Authors: Title, Alan M.; Frank, Zoe A.; Shine, Richard A.; Tarbell,
T. D.; Topka, K. P.; Scharmer, Goran; Schmidt, Wolfgang
Bibcode: 1992ASIC..375..195T
Altcode: 1992sto..work..195T
We have observed the disk passage of relatively simple round sunspots
using a narrowband filter and a large format CCD detector and have
created magnetograms, Dopplergrams, and continuum images nearly
simultaneously. In addition the spectral resolution of the filter
allows the construction of 'spectra' for all points in the field of
view. The mean inclination of the magnetic field increases from 45-50
deg to 70-75 deg across the penumbra and there is a fluctuation of the
inclination angle about the mean of about 4 +/- 18 deg. The variation in
inclination is large enough that substantial amounts of magnetic field
are parallel to the solar surface from the mid to outer penumbra. The
Evershed flow tends to occur in the regions where the magnetic field
is horizontal. This suggests that the Evershed flow is confined to the
regions of horizontal fields. We show that a simple sunspot model with
azimuthal variations in inclination but no azimuthal variations of
field strength is free from azimuthal Lorentz forces. The meridional
component of the currents which arise from the azimuthal variation
in inclination are parallel to the field lines. This suggests that a
cylindrically symmetric magnetostatic sunspot model can be perturbed
into one with azimuthal variations in inclination with some adjustment
in the meridional force balance.
Title: Dynamics of the Quiet Solar Atmosphere: K2v Cell Grains Versus
Magnetic Elements
Authors: Brandt, P. N.; Rutten, R. J.; Shine, R. A.; Trujillo Bueno, J.
Bibcode: 1992ASPC...26..161B
Altcode: 1992csss....7..161B
No abstract at ADS
Title: An Investigation of the Flare Star AU Mic with the Goddard
High Resolution Spectrograph on the Hubble Space Telescope
Authors: Maran, S. P.; Woodgate, B. E.; Carpenter, K. G.; Robinson,
R. D.; Shore, S. N.; Linsky, J. L.; Brown, A.; Byrne, P. B.; Kundu,
M. R.; White, S.; Brandt, J. C.; Shine, R. A.; Walter, F. M.
Bibcode: 1991BAAS...23.1382M
Altcode:
No abstract at ADS
Title: Observations of the Birth and Death of Mesogranules
Authors: Simon, G. W.; Title, A. M.; Shine, R. A.; Frank, Z.; Muller,
R.; Auffret, H.
Bibcode: 1991BAAS...23.1034S
Altcode:
No abstract at ADS
Title: Field Geometry of Sunspots Inferred from Inclination Effects
Authors: Title, A. M.; Frank, Z. A.; Shine, R. A.; Tarbell, T. D.
Bibcode: 1991BAAS...23R1052T
Altcode:
No abstract at ADS
Title: Sunspot Umbral and Penumbral Oscillations in Hα
Authors: Shine, R.; Tarbell, T.; Title, A.; Topka, K.; Frank, Z.;
Smith, K.
Bibcode: 1991BAAS...23.1033S
Altcode:
No abstract at ADS
Title: Variation of granulation properties on a mesogranular scale
Authors: Brandt, P. N.; Ferguson, S.; Shine, R. A.; Tarbell, T. D.;
Scharmer, G. B.
Bibcode: 1991A&A...241..219B
Altcode:
A 79 min series of CCD images of the solar granulation with subarcsec
spatial resolution is analyzed. Local correlation techniques are applied
to determine horizontal displacements of the granular intensity pattern
in a 14.2 by 12.2 sq arcsec field of view. The divergence of the average
horizontal flow field shows mean cell sizes of 5 to 7 arcsec. Granules
are selected with respect to area, brightness, lifetime, and expansion
rate. It is shown that small, faint, short-lived, and fast collapsing
granules are located preferentially in the negative divergence
(down-draft) regions of the mesogranular flow field, while bright,
long-lived, and rapidly expanding granules populate preferentially
the positive divergence (up-draft) regions. The differences in area
coverage range between + or - 6 percent and + or - 9 percent.
Title: Results from high resolution solar images and spectra obtained
at the Pic du Midi Observatory (1986-1990)
Authors: Roudier, Th.; Muller, R.; Vigneau, J.; Auffret, H.; Espagnet,
O.; Simon, G. W.; Title, A. M.; Frank, Z.; Shine, R. A.; Tarbell,
T. D.; Mein, P.; Malherbe, J. M.
Bibcode: 1991AdSpR..11e.205R
Altcode: 1991AdSpR..11..205R
We present an overview of our recent results about solar granulation and
mesogranulation, obtained with Pic du Midi observations. These results
were obtained during 1986-1990 using image and spectrographic analysis
of high spatial resolution data. The study of the solar granulation,
with 2 Dim. ``Multichannel Subtractive Double Pass'' (M.S.D.P.) spectra,
shows a clear change of the dynamical regime at 3'' (⋍ 2200 km)
of the photospheric velocity field when oscillatory components are
filtered out. A three hour movie obtained on film at Pic du Midi
Observatory and analyzed at the Lockheed Research Laboratory and the
National Solar Observatory (Sacramento Peak) was used to calculate
the horizontal flow pattern. The mean lifetime of the diverging areas
related to mesogranulation is estimated at 3 hours; these diverging
areas are swept by the supergranulation flow towards the supergranule
boundary with a mean speed of 0.4 km/s.
Title: Generation of Electric Currents and Waves on Magnetic Flux
Tubes by Horizontal Velocities in the Photosphere (With 1 Figure)
Authors: Tarbell, T. D.; Slater, G. L.; Frank, Z. A.; Shine, R. A.;
Topka, K. P.
Bibcode: 1991mcch.conf...39T
Altcode:
No abstract at ADS
Title: SOUP Observations of Solar Activity
Authors: Shine, R. A.; Scharmer, G.; Tarbell, T. D.; Title, A. M.;
Topka, K. P.
Bibcode: 1991max..conf..295S
Altcode:
No abstract at ADS
Title: Detailed Comparison of Quiet and Magnetic Sun
Authors: Topka, K.; Ferguson, S.; Shine, R.; Tarbell, T.; Title, A.;
Balke, C.; Scharmer, G.; Schmidt, W.
Bibcode: 1990BAAS...22R.879T
Altcode:
No abstract at ADS
Title: Penumbral Flows and Magnetic Fields
Authors: Shine, R.; Smith, K.; Tarbell, T.; Title, A.; Scharmer, G.
Bibcode: 1990BAAS...22..878S
Altcode:
No abstract at ADS
Title: Generation of Waves and Electric Currents on Magnetic Flux
Tubes by Horizontal and Vertical Velocities in the Photosphere
Authors: Frank, Z. A.; Shine, R. A.; Slater, G.; Tarbell, T.; Topka, K.
Bibcode: 1990BAAS...22..878F
Altcode:
No abstract at ADS
Title: High-Resolution Observations of Emerging Magnetic Fields and
Flux Tubes in Active Region Photosphere
Authors: Tarbell, T.; Ferguson, S.; Frank, Z.; Shine, R.; Title, A.;
Topka, K.; Scharmer, G.
Bibcode: 1990IAUS..138..147T
Altcode:
No abstract at ADS
Title: Structure and Evolution of the Large Scale Granulation
Authors: Muller, R.; Roudier, Th.; Vigneau, J.; Frank, Z.; Shine,
R.; Tarbell, T.; Title, A.; Simon, G.
Bibcode: 1990PDHO....7...44M
Altcode: 1990dysu.conf...44M; 1990ESPM....6...44M
A granulation movie of 3 hours has been performed at the Pic du Midi
Observatory on September 20, 1988.
Title: High Resolution Observations of the Photosphere
Authors: Title, A. M.; Shine, R. A.; Tarbell, T. D.; Topka, K. P.;
Scharmer, G. B.
Bibcode: 1990IAUS..138...49T
Altcode:
No abstract at ADS
Title: Formation of Network Bright Points by Granule Compression
Authors: Muller, R.; Roudier, Th.; Vigneau, J.; Frank, Z.; Shine,
R.; Tarbell, T.; Title, A.; Simon, G.
Bibcode: 1990PDHO....7..150M
Altcode: 1990dysu.conf..150M; 1990ESPM....6..150M
No abstract at ADS
Title: Intial Results of the Lockheed 1989 La Palma Observing Campaign
Authors: Topka, K.; Frank, Z.; Shine, R.; Smith, K.; Tarbell, T.;
Title, A.; Scharmer, G.
Bibcode: 1989BAAS...21.1111T
Altcode:
No abstract at ADS
Title: Variation of granulation properties on a meso-granular scale
Authors: Brandt, P. N.; Ferguson, S.; Scharmer, G. B.; Shine, R. A.;
Tarbell, T. D.; Title, A. M.; Topka, K.
Bibcode: 1989hsrs.conf..473B
Altcode:
No abstract at ADS
Title: Proper Motion and Lifetime of Mesogranules
Authors: Frank, Z.; Muller, R.; Roudier, T.; Vigneau, J.; Shine, R.;
Tarbell, T.; Title, A.; Topka, K.; Simon, G.
Bibcode: 1989BAAS...21..841F
Altcode:
No abstract at ADS
Title: Short Term Evolution of Fine Scale Magnetic Structures
Authors: Topka, K.; Frank, Z.; Shine, R.; Tarbell, T.; Title, A.;
Scharmer, G.; Balke, A.
Bibcode: 1989BAAS...21..842T
Altcode:
No abstract at ADS
Title: Magnetic Field Inclination in Penumbra of a Round Sunspot
Observed at Very High Spatial Resolution
Authors: Title, A. M.; Frank, Z. A.; Shine, R. A.; Tarbell, T. D.;
Scharmer, G.
Bibcode: 1989BAAS...21Q.837T
Altcode:
No abstract at ADS
Title: Investigation of Active Regions at High Resolution by Balloon
Flights of the Solar Optical Universal Polarimeter (SOUP)
Authors: Tarbell, T.; Gilbreth, C.; Shine, R.; Title, A.; Topka, K.;
Wolfson, J.
Bibcode: 1989BAAS...21R.837T
Altcode:
No abstract at ADS
Title: Observations of Running Penumbral Waves
Authors: Shine, R.; Tarbell, T.; Title, A.; Topka, K.; Frank, Z.;
Scharmer, G.
Bibcode: 1989BAAS...21..837S
Altcode:
No abstract at ADS
Title: Generation of Waves on Magnetic Flux Tubes by Horizontal
Velocities in the Photosphere
Authors: Tarbell, T. D.; Ferguson, S. H.; Frank, Z. A.; Shine, R. A.
Bibcode: 1989BAAS...21..830T
Altcode:
No abstract at ADS
Title: Details of Large Scale Solar Motions Revealed by Granulation
Test Particles
Authors: Simon, G. W.; November, L. J.; Ferguson, S. H.; Shine, R. A.;
Tarbell, T. D.; Title, A. M.; Topka, K. P.; Zirin, H.
Bibcode: 1989ASIC..263..371S
Altcode: 1989ssg..conf..371S
No abstract at ADS
Title: Statistical Properties of Solar Granulation Derived from the
SOUP Instrument on Spacelab 2
Authors: Title, A. M.; Tarbell, T. D.; Topka, K. P.; Ferguson, S. H.;
Shine, R. A.; SOUP Team
Bibcode: 1989ApJ...336..475T
Altcode:
Computer algorithms and statistical techniques were used to identify,
measure, and quantify the properties of solar granulation derived
from movies collected by the Solar Optical Universal Polarimeter on
Spacelab 2. The results show that there is neither a typical solar
granule nor a typical granule evolution. A granule's evolution is
dependent on local magnetic flux density, its position with respect to
the active region plage, its position in the mesogranulation pattern,
and the evolution of granules in its immediate neighborhood.
Title: Flows, Random Motions and Oscillations in Solar Granulation
Derived from the SOUP Instrument on Spacelab 2
Authors: Title, A. M.; Tarbell, T. D.; Topka, K. P.; Ferguson, S. H.;
Shine, R. A.; SOUP Team
Bibcode: 1989ASIC..263..225T
Altcode: 1989ssg..conf..225T
No abstract at ADS
Title: Magnetoconvection on the solar surface.
Authors: Simon, G. W.; Title, A. M.; Topka, K. P.; Tarbell, T. D.;
Shine, R. A.; Ferguson, S. H.; Zirin, H.
Bibcode: 1989GMS....54...53S
Altcode: 1989sspp.conf...53S
The authors describe and illustrate the first high-resolution
observations of horizontal flows on the solar surface and their relation
to magnetic field structure seen in the Sun's photosphere.
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.
Bibcode: 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: Vortex Motion of the Solar Granulation
Authors: Brandt, P. N.; Scharmer, G. B.; Ferguson, S. H.; Shine,
R. A.; Tarbell, T. D.; Title, A. M.
Bibcode: 1989ASIC..263..305B
Altcode: 1989ssg..conf..305B
No abstract at ADS
Title: Investigation of active regions at high resolution by balloon
flights of the Solar Optical Universal Polarimeter (SOUP)
Authors: Tarbell, T.; Frank, Z.; Gilbreth, C.; Shine, R.; Title, A.;
Topka, K.; Wolfson, J.
Bibcode: 1989dots.work..310T
Altcode:
SOUP is a versatile, visible-light solar observatory, built for space
or balloon flight. It is designed to study magnetic and velocity
fields in the solar atmosphere with high spatial resolution and
temporal uniformity, which cannot be achieved from the surface of the
earth. The SOUP investigation is carried out by the Lockheed Palo Alto
Research Laboratory, under contract to NASA's Marshall Space Flight
Center. Co-investigators include staff members at a dozen observatories
and universities in the U.S. and Europe. The primary objectives of the
SOUP experiment are: to measure vector magnetic and velocity fields in
the solar atmosphere with much better spatial resolution than can be
achieved from the ground; to study the physical processes that store
magnetic energy in active regions and the conditions that trigger
its release; and to understand how magnetic flux emerges, evolves,
combines, and disappears on spatial scales of 400 to 100,000 km. SOUP
is designed to study intensity, magnetic, and velocity fields in the
photosphere and low chromosphere with 0.5 arcsec resolution, free of
atmospheric disturbances. The instrument includes: a 30 cm Cassegrain
telescope; an active mirror for image stabilization; broadband film
and TV cameras; a birefringent filter, tunable over 5100 to 6600 A
with 0.05 A bandpass; a 35 mm film camera and a digital CCD camera
behind the filter; and a high-speed digital image processor.
Title: Observations of f- and p-mode oscillations of high degree
(500 < l < 2500) in quiet and active Sun.
Authors: Tarbell, T. D.; Peri, M.; Frank, Z.; Shine, R.; Title, A. M.
Bibcode: 1988ESASP.286..315T
Altcode: 1988ssls.rept..315T
Spectra (l-ν diagrams) from high resolution observations taken at
the Vacuum Tower Telescope (NSO/Sunspot) are presented. The raw data
are CCD images taken through the SOUP narrowband filter in Fe I 5576
Å. Four filtergrams spaced through the spectral line are combined to
form velocity movies. Spectra for 80 minutes of data with 0.5 - 1.5
arcsecond resolution are presented for the entire field-of-view and
for quiet and magnetic (plage) subregions. Ridges f and p1 -
p5 are evident in velocity spectra, extending to l = 2500(f),
l = 1800(p1), and l = 1200(p2). Much less power is
seen in the magnetic region than in the quiet sun. Three-dimensional
Fourier filtering shows that oscillation velocity amplitude drops
sharply at the boundary of the active region for each family of modes
considered.
Title: Active region evolution in the chromosphere and transition
region
Authors: Shine, R. A.; Schrijver, C. J.
Bibcode: 1988fnsm.work...29S
Altcode:
Images in the C IV 1548 A and the Si II 1526 S lines taken with the
ultraviolet spectrometer polarimeter (UVSP) instrument on board the
Solar Maximum Mission (SMM) satellite were combined into movies showing
the evolution of active regions and the neighboring supergranulation
over several days. The data sets generally consist of 240 by 240 arc
second rasters with 3 arc second pixels taken one per orbit (about every
90 minutes). The images are projected on a latitude/longitude grid to
remove the forshortening as the region rotates across the solar disk
and further processed to remove jitter and gain variations. Movies
were made with and without differential rotation. Although there are
occasional missing orbits, these series do not suffer from the long
nighttime gaps that occur in observations taken at a single groundbased
observatory and are excellent for studying changes on time scales of
several hours. The longest sequence processed to date runs from 20
Oct. 1980 to 25 Oct. 1980. This was taken during an SMM flare buildup
study on AR 2744. Several shorter sequences taken in 1980 and 1984
will also be shown. The results will be presented on a video disk
which can be interactively controlled to view the movies.
Title: Statistical properties of solar granulation from the SOUP
instrument on Spacelab 2
Authors: Topka, K.; Title, A.; Tarbell, T.; Ferguson, S.; Shine, R.
Bibcode: 1988fnsm.work..294T
Altcode:
The Solar Optical Universal Polarimeter (SOUP) on Spacelab 2 collected
movies of solar granulation completely free from atmospheric blurring,
and are not degraded by pointint jitter (the pointing stability
was 0.003 sec root mean square). The movies illustrate that the
solar five minute oscillation has a major role in the appearance of
solar granulation and that exploding granules are a common feature
of the granule evolution. Using 3-D Fourier filtering techniques
the oscillations were removed and it was demonstrated that the
autocorrelation lifetime of granulation is a factor of two greater
in magnetic field regions than in field-free quiet sun. Horizontal
velocities were measured and flow patterns were observed on the scale of
meso- and super granulation. In quiet regions the mean flow velocity
is 370 m/s while in the magnetic regions it is about 125 m/s. It
was also found that the root mean square (RMS) fluctuating horizonal
velocity field is substantially greater in quiet sun than in strong
magnetic field regions. By superimposing the location of exploding
granules on the average flow maps it was found that they appear almost
exclusively in the center of mesogranulation size flow cells. Because
of the nonuniformity of the distribution of exploding granules, the
evolution of the granulation pattern in mesogranule cell centers and
boundaries differs fundamentally. It is clear from this study there
is neither a typical granule nor a typical granule evolution.
Title: Observations of Granulation in Quiet and Magnetic Sun from
the Swedish Solar Observatory on LaPalma
Authors: Topka, K.; Ferguson, S.; Frank, Z.; Shine, R.; Tarbell, T.;
Title, A.; Wolfson, J.; Scharmer, G.; Brandt, P.
Bibcode: 1988BAAS...20S1010T
Altcode:
No abstract at ADS
Title: Solar Activity and Flare Observations from the Swedish Solar
Observatory on La Palma
Authors: Wolfson, J.; Ferguson, S.; Frank, Z.; Shine, R.; Tarbell,
T.; Title, A.; Topka, K.; Scharmer, G.; Brandt, P.; Gurman, J.
Bibcode: 1988BAAS...20..978W
Altcode:
No abstract at ADS
Title: Vortex flow in the solar photosphere
Authors: Brandt, P. N.; Scharmer, G. B.; Ferguson, S.; Shine, R. A.;
Tarbell, T. D.; Title, A. M.
Bibcode: 1988Natur.335..238B
Altcode:
Convective flow fields in the solar atmosphere play a key role in the
concentration and dispersal of magnetic flux1, but because
the individual flow elements-the solar granules-are a few arcsec or less
in size, studies of their motions have been limited by the distortion
and blurring of the Earth's atmosphere ('seeing'). We report here a
very high-quality series of granulation images taken at the new Swedish
Solar Observatory on La Palma (Canary Islands) which have permitted
flow measurements at the sub-arcsec level. These movies show a vortex
structure which visibly dominates the motion of the granules in its
neighbourhood and persists for the 1.5 h duration of the movie. If such
vortices are a common feature of the solar convective zone, they may
provide an important mechanism for the heating of stellar chromospheres
and coronae by twisting the footprints of magnetic flux tubes.
Title: On the Relation between Photospheric Flow Fields and the
Magnetic Field Distribution on the Solar Surface
Authors: Simon, George W.; Title, A. M.; Topka, K. P.; Tarbell, T. D.;
Shine, R. A.; Ferguson, S. H.; Zirin, H.; SOUP Team
Bibcode: 1988ApJ...327..964S
Altcode:
Using the technique of local correlation tracking on a 28 minute time
sequence of white-light images of solar granulation, the horizontal
flow field on the solar surface is measured. The time series was
obtained by the Solar Optical Universal Polarimeter (SOUP) on Spacelab 2
(Space Shuttle flight 51-F) and is free from atmospheric blurring and
distortion. The SOUP flow fields have been compared with carefully
aligned magnetograms taken over a nine hour period at the Big Bear
Solar Observatory before, during, and after the SOUP images. The flow
field and the magnetic field agree in considerable detail: vectors which
define the flow of the white-light intensity pattern (granulation) point
toward magnetic field regions, magnetic fields surround flow cells, and
magnetic features move along the flow arrows. The projected locations
of free particles ('corks') in the measured flow field congregate at
the same locations where the magnetic field is observed.
Title: Observations of F-and P-Mode Oscillations of High Degree
(500< <3500) in Quiet and Active Sun
Authors: Peri, M.; Frank, Z.; Shine, R.; Tarbell, T.; Title, A.
Bibcode: 1988BAAS...20..702P
Altcode:
No abstract at ADS
Title: Active Region Evolution in the Chromosphere and Transition
Region
Authors: Shine, R. A.; Schrijver, C.
Bibcode: 1988BAAS...20..744S
Altcode:
No abstract at ADS
Title: Solar Granulation Movies of Exceptional Spatial Resolution:
Observations and Simulations of Horizontal Convective Flows
Authors: Title, A.; Shine, R.; Ferguson, S.; Tarbell, T.; Brandt,
P.; Scharmer, G.
Bibcode: 1988BAAS...20R.679T
Altcode:
No abstract at ADS
Title: Statistical Properties of Solar Granulation from the SOUP
Instrument on Spacelab 2
Authors: Topka, K.; Title, A.; Tarbell, T.; Ferguson, S.; Shine, R.
Bibcode: 1988BAAS...20Q.679T
Altcode:
No abstract at ADS
Title: Variability of solar mesogranulation
Authors: Simon, G. W.; November, L. J.; Acton, L. W.; Ferguson, S. H.;
Shine, R. A.; Tarbell, T. D.; Title, A. M.; Topka, K. P.; Zirin, H.
Bibcode: 1988AdSpR...8g.169S
Altcode: 1988AdSpR...8..169S
From white-light photographs of solar granulation obtained with the
SOUP instrument on Space Shuttle Flight STS-19 we have measured the
motions of granules using local correlation tracking techniques. The
granules are organized into larger-scale structures (mesogranular and
supergranular) which exhibit outflow from upwellings, convergence into
sinks, as well as significant vorticity. Magnetic fields follow these
same flow patterns. We describe these velocity structures, and suggest
that their effect on magnetic field structures may be important to
the solar flare buildup process.
Title: Correlation Lifetimes of Quiet and Magnetic Granulation from
the SOUP Instrument on Spacelab 2
Authors: Title, A.; Tarbell, T.; Topka, K.; Acton, L.; Duncan, D.;
Ferguson, S.; Finch, M.; Frank, Z.; Kelly, G.; Lindgren, R.; Morrill,
M.; Pope, T.; Reeves, R.; Rehse, R.; Shine, R.; Simon, G.; Harvey,
J.; Leibacher, J.; Livingston, W.; November, L.; Zirker, J.
Bibcode: 1988ApL&C..27..141T
Altcode:
The time sequences of diffraction limited granulation images obtained by
the Solar Optical Universal Polarimeter on Spacelab 2 are presented. The
uncorrection autocorrelation limetime in magnetic regions is dominated
by the 5-min oscillation. The removal of this oscillation causes the
autocorrelation lifetime to increase by more than a factor of 2. The
results suggest that a significant fraction of granule lifetimes are
terminated by nearby explosions. Horizontal displacements and transverse
velocities in the intensity field are measured. Lower limits to the
lifetime in the quiet and magnetic sun are set at 440 s and 950 s,
respectively.
Title: The relation between convection flows and magnetic structure
at the solar surface
Authors: Simon, G. W.; November, L. J.; Acton, L. W.; Title, A. M.;
Tarbell, T. D.; Topka, K. P.; Shine, R. A.; Ferguson, S. H.; Weiss,
N. O.; Zirin, H.
Bibcode: 1988AdSpR...8k.133S
Altcode: 1988AdSpR...8..133S
We describe recent results from the comparison of data from the Solar
Optical Universal Polarimeter instrument on Spacelab 2 and magnetograms
from Big Bear Solar Observatory. We show that the Sun's surface velocity
field governs the structure of the observed magnetic field over the
entire solar surface outside sunspots and pores. We attempt to describe
the observed flows by a simple axisymmetric plume model. Finally,
we suggest that these observations may have important implications
for the prediction of solar flares, mass ejections, and coronal heating.
Title: White Light Sunspot Observations from the Solar Optical
Universal Polarimeter on Spacelab-2
Authors: Shine, R. A.; Title, A. M.; Tarbell, T. D.; Topka, K. P.
Bibcode: 1987Sci...238.1264S
Altcode:
The flight of the Solar Optical Universal Polarimeter on Spacelab-2
provided the opportunity for the collection of time sequences of
diffraction-limited (0.5 arc second) solar images with excellent
pointing stability (0.003 arc second) and with freedom from the
distortion that plagues ground-based images. A series of white-light
images of active region 4682 were obtained on 5 August 1985, and
the area containing the sunspot has been analyzed. These data have
been digitally processed to remove noise and to separate waves from
low-velocity material motions. The results include (i) proper motion
measurements of a radial outflow in the photospheric granulation
pattern just outside the penumbra; (ii) discovery of occasional bright
structures (``streakers'') that appear to be ejected outward from the
penumbra; (iii) broad dark ``clouds'' moving outward in the penumbra,
in addition to the well-known bright penumbral grains moving inward;
(iv) apparent extensions and contractions of penumbral filaments over
the photosphere; and (v) observation of a faint bubble or looplike
structure that seems to expand from two bright penumbral filaments
into the photosphere.
Title: Vortex Flow in Granulation
Authors: Scharmer, G.; Brandt, P.; Title, A.; Shine, R.; Ferguson, S.
Bibcode: 1987BAAS...19Q1118S
Altcode:
No abstract at ADS
Title: High-Resolution CCD Observations of Doppler and Magnetic
Images in the Solar Photosphere
Authors: Tarbell, T. D.; Frank, Z. A.; Morrill, M. E.; Shine, R. A.;
Topka, K. P.; Title, A. M.
Bibcode: 1987BAAS...19.1117T
Altcode:
No abstract at ADS
Title: Sunspot observations from the SOUP instrument on Spacelab 2.
Authors: Shine, R. A.; Title, A. M.; Tarbell, T. D.; Acton, L.; Duncan,
D.; Ferguson, S. H.; Finch, M.; Frank, Z.; Kelly, G.; Lindgren, R.
Bibcode: 1987NASCP2483..133S
Altcode: 1987tphr.conf..133S
A series of white light images obtained by the SOUP instrument on
Spacelab 2 of active region 4682 on August 5, 1985 were analyzed
in the area containing sunspots. Although the umbra of the spot is
underexposed, the film is well exposed in the penumbral regions. These
data were digitally processed to remove noise and to separate p-mode
oscillations from low velocity material motions. The results of this
preliminary investigation include: (1) proper motion measurements of
a radial outflow in the photospheric granulation pattern just outside
the penumbra; (2) discovery of occasional bright structures (streakers)
that appear to be ejected outward from the penumbra; (3) broad dark
clouds moving outward in the penumbra in addition to the well known
bright penumbral grains moving inward; (4) apparent extensions and
contractions of penumbral filaments over the photosphere; and (5)
observation of a faint bubble or loop-like structure which seems to
expand from two bright penumbral filaments into the photosphere.
Title: Simultaneous Sunspot Observations from the SOUP Instrument
on Spacelab 2 and the Big Bear Solar Observatory
Authors: Shine, R. A.; Title, A. M.; Topka, K. P.; Tarbell, T. D.;
Zirin, H.
Bibcode: 1987BAAS...19..927S
Altcode:
No abstract at ADS
Title: Ocean Waves in the Photosphere: Measurements of Oscillations
with Wavelengths of 1 - 10 Mm from SOUP White Light Images
Authors: Tarbell, T. D.; Shine, R. A.; Ferguson, S. H.; Title, A. M.;
Leibacher, J. W.
Bibcode: 1987BAAS...19Q.936T
Altcode:
No abstract at ADS
Title: New Ideas About Granulation Based on Data from the Solar
Optical Universal Polarimeter Instrument on Spacelab 2 and Magnetic
Data from Big Bear Solar Observatory
Authors: Title, A. M.; Tarbell, T. D.; Topka, K. P.; Shine, R. A.;
Simon, G. W.; Zirin, H.; SOUP Team
Bibcode: 1987LNP...292..173T
Altcode: 1987ssp..conf..173T
The SOUP flow fields have been compared with carefully aligned
magnetograms taken at the BBSO before, during, and after the SOUP
images. The magnetic field is observed to exist in locations where
either the flow is convergent or on the boundaries of the outflow from
a flow cell center. Streamlines calculated from the flow field agree
very well with the observed motions of the magnetic field in the BBSO
magnetogram movies.
Title: SMM Observations of SI IV and O IV Bursts in Solar Active
Regions
Authors: Hayes, Marion; Shine, R. A.
Bibcode: 1987ApJ...312..943H
Altcode:
Observations of Si IV and O IV lines in solar active regions taken
by the ultraviolet spectrometer and polarimeter on board the SMM are
analyzed. The average frequency of UV bursts of all types is one every
four minutes in a 28 arcsec by 28 arcsec field of view. About 80 percent
of the bursts show an increased Si IV/O IV ratio, suggesting a density
increase. The indicated electron densities are generally in the 10 to
the 11th-12th range, with 16 percent indicating higher densities. Some
of the more energetic bursts exhibit flarelike characteristics, and
some of these show a secondary brightening which may be an analog of
the soft X-ray gradual phase of flares. The high frequency of these
UV bursts and their possible association with hard X-ray 'microflares'
and chromospheric evaporation may make them extremely important in the
energetics of active regions and in the maintenance of their enhanced
coronal emission.
Title: Spectral Line Profiles of Fe XXI 1354.1 Angstrom from the
Solar Maximum Mission
Authors: Mason, H. E.; Shine, R. A.; Gurman, J. B.; Harrison, R. A.
Bibcode: 1986ApJ...309..435M
Altcode:
Observations of the Fe XXI 1354.1 A line were obtained for several
flares using the SMM-UVSP instrument with varying spectral and spatial
resolution. Of special interest are spectral line profiles from the
footpoints of flare loops taken during the impulsive phase. These
data show blueshifted Fe XXI profiles coincident and cospatial with
the impulsive brightening of chromospheric material. The present
analysis supports the hypothesis that the blueshifted component of the
high temperature emission is an integral part of the flare, possibly
associated with chromospheric evaporation.
Title: SMM Observations of Non-Linear Oscillations in the C IV 1548Å
Line above a Sunspot
Authors: Shine, R. A.; McWhirter, R. W. P.
Bibcode: 1986BAAS...18Q.990S
Altcode:
No abstract at ADS
Title: White Light Observations of a Sunspot Penumbra and its
Interaction with the Surrounding Photosphere
Authors: Shine, R. A.; SOUP Team
Bibcode: 1986BAAS...18..661S
Altcode:
No abstract at ADS
Title: Second Generation Spectrograph for the Hubble Space Telescope
Authors: Maran, S. P.; Woodgate, B. E.; Boggess, A.; Gull, T. R.;
Heap, S. R.; Melcher, R.; Green, R. F.; Wolff, S. C.; Hutchings, J. B.;
Jenkins, E. B.; Linsky, J. L.; Moos, H. W.; Roesler, F.; Shine, R. A.;
Timothy, J. G.; Weistrop, D. E.
Bibcode: 1986BAAS...18..636M
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.
Bibcode: 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: Second generation spectrograph for the Hubble Space Telescope.
Authors: Woodgate, B. E.; Boggess, A.; Gull, T. R.; Heap, S. R.;
Krueger, V. L.; Maran, S. P.; Melcher, R. W.; Rebar, F. J.; Vitagliano,
H. D.; Green, R. F.; Wolff, S. C.; Hutchings, J. B.; Jenkins, E. B.;
Linsky, J. L.; Moos, H. W.; Roesler, F.; Shine, R. A.; Timothy, J. G.;
Weistrop, D. E.; Bottema, M.; Meyer, W.
Bibcode: 1986SPIE..627..350W
Altcode:
The preliminary design for the Space Telescope Imaging Spectrograph
(STIS), which has been selected by NASA for definition study for future
flight as a second-generation instrument on the Hubble Space Telescope
(HST), is presented. STIS is a two-dimensional spectrograph that
will operate from 1050 A to 11,000 A at the limiting HST resolution
of 0.05 arcsec FWHM, with spectral resolutions of 100, 1200, 20,000,
and 100,000 and a maximum field-of-view of 50 x 50 arcsec. Its basic
operating modes include echelle model, long slit mode, slitless
spectrograph mode, coronographic spectroscopy, photon time-tagging,
and direct imaging. Research objectives are active galactic nuclei,
the intergalactic medium, global properties of galaxies, the origin
of stellar systems, stelalr spectral variability, and spectrographic
mapping of solar system processes.
Title: White-light movies of the solar photosphere from the soup
instrument on spacelab 2
Authors: Title, A. M.; Tarbell, T. D.; Simon, G. W.; Acton, L.;
Duncan, D.; Ferguson, S.; Finch, M.; Frank, Z.; Kelly, G.; Lindgren,
R.; Morrill, M.; Pope, T.; Reeves, R.; Rehse, R.; Shine, R.; Topka,
K.; Harvey, J.; Leibacher, J.; Livingston, W.; November, L.
Bibcode: 1986AdSpR...6h.253T
Altcode: 1986AdSpR...6..253T
We present initial results on solar granulation, pores and sunspots
from the white-light films obtained by the Solar Optical Universal
Polarimeter (SOUP) instrument on Spacelab 2. SOUP contains a
30-cm Cassegrain telescope, an active secondary mirror for image
stabilization, and a white-light optical system with 35-mm film
and video cameras. Outputs from the fine guidance servo provided
engineering data on the performance of the ESA Instrument Pointing
System (IPS). Several hours of movies were taken at various
disk and limb positions in quiet and active regions. The images
are diffraction-limited at 0.5 arc second resolution and are, of
course, free of atmospheric seeing and distortion. Properties of the
granulation in magnetic and non-magnetic regions are compared and are
found to differ significantly in size, rate of intensity variation,
and lifetime. In quiet sun on the order of fifty percent of the area
has at least one ``exploding granule'' occurring in it during a 25
minute period. Local correlation tracking has detected several types
of transverse flows, including systematic outflow from the penumbral
boundary of a spot, motion of penumbral filaments, and cellular flow
patterns of supergranular and mesogranular size. Feature tracking has
shown that in quiet sun the average granule fragment has a velocity
of about one kilometer per second.
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.
Bibcode: 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: Association of Small, Bright Photospheric Features with
Magnetic Fields
Authors: Topka, K.; Shine, R.; SOUP Team
Bibcode: 1985BAAS...17..834T
Altcode:
No abstract at ADS
Title: Erratum - a Study of Flare Buildup from Simultaneous
Observations in Microwave Hα and Ultraviolet Wavelengths
Authors: Kundu, M. R.; Gaizauskas, V.; Woodgate, B. E.; Schmahl,
E. J.; Shine, R.; Jones, H. P.
Bibcode: 1985ApJS...58..195K
Altcode:
No abstract at ADS
Title: A study of flare buildup from simultaneous observations in
microwave, H-alpha, and UV wavelengths
Authors: Kundu, M. R.; Gaizauskas, V.; Woodgate, B. E.; Schmahl,
E. J.; Shine, R.; Jones, H. P.
Bibcode: 1985ApJS...57..621K
Altcode:
The results of high-resolution observations of the solar preflare
activity of June 25, 1980 are analyzed. The observations were carried
out simultaneously in the UV microwave, and H-alpha wavelengths
using the VLA, the Ottawa River photoheliograph, and the Solar Max
spectrometer and polarimeter instruments. Increases were observed in the
intensitiy and polarization of compact sources at a wavelength of 6-cm
during the preflare hour. The increases were associated with rising and
twisting motions in the magnetic loops near the sight of the subsequent
flare. Consistent with this process, analysis of the transverse and
Doppler motions observed in the H-alpha filament before disruption
showed that the filament was activated internally by the motions of
evolving magnetic flux patterns. Ultraviolet data for C IV brightenings
and upflows at the first appearance of the H-alpha filament indicated
the presence of rising magnetic loops and material rising within the
loops. The complete VLA, microwave and H-alpha data sets are given.
Title: Absolute Wavelength Measurements of Solar UV Emission Lines
Authors: Bruner, M. E.; Shine, R. A.
Bibcode: 1985BAAS...17..630B
Altcode:
No abstract at ADS
Title: Energy Release and Energy Transport Below the Transition Zone
in Solar Flares
Authors: Hénoux, J. C.; Chambe, G.; Heristchi, D.; Semel, M.;
Woodgate, B.; Shine, R.; Beckers, J.
Bibcode: 1985spit.conf..758H
Altcode:
No abstract at ADS
Title: Center-to-Limb Variation of Transition Region Redshift
Authors: Shine, R. A.; Woodgate, B. E.; Gurman, J. B.
Bibcode: 1984BAAS...16..992S
Altcode:
No abstract at ADS
Title: Evidence for Chromospheric Evaporation in Solar Flares from
UV Observations
Authors: Shine, R. A.; Mason, H. E.
Bibcode: 1984BAAS...16..543S
Altcode:
No abstract at ADS
Title: Scientific Results from the Ultraviolet Spectrometer and
Polarimeter on SMM
Authors: Shine, R. A.
Bibcode: 1984stp..conf...91S
Altcode:
No abstract at ADS
Title: Optical, microwave and UV imagery of a solar flare.
Authors: Gaizauskas, V.; Kundu, M. R.; Schmahl, E. J.; Shine, R. A.;
Woodgate, B. E.
Bibcode: 1983JRASC..77..261G
Altcode:
No abstract at ADS
Title: Formation of the CL I line at 1351 A in the solar chromosphere
Authors: Shine, R. A.
Bibcode: 1983ApJ...266..882S
Altcode:
The formation of the multiplet containing the Cl I 1351 A line
is investigated due to the unusual brightness of this line. It is
determined that this line is formed via a fluorescence effect driven
by the 1335 A line of C II. Non-LTE calculations including this effect
are found to agree with the observed line intensity. It is shown that
the 1347 and 1363 A lines of Cl I do not benefit from this effect and
they are predicted to be approximately 100 times weaker.
Title: Conductive flux in flaring solar chromospheres deduced from
the linear polarization observations
Authors: Henoux, J. C.; Heristchi, D.; Chambe, G.; Woodgate, B.;
Shine, R.; Beckers, J.; Machado, M.
Bibcode: 1983A&A...119..233H
Altcode:
The linear polarization of Hα and S I 1437 Å lines produced in
impact excitation by energetic electrons with an anisotropic velocity
distribution function during solar flares is calculated. Selecting
a function which represents the velocity distribution of electrons
carrying heat flux, the relationship between conductive heat flux and
linear line polarization has been computed. The application of the
relationship between linear polarization and heat flux to the observed
degree of polarization leads to the determination of the conductive
heat flux at the top of flaring chromospheric layers. This conductive
flux is of the order of magnitude of the total radiation loss in the
chromosphere and below, which is also of the order of magnitude of
the conductive flux in the transition zone.
Title: Simultaneous ultraviolet line and hard X-ray bursts in the
impulsive phase of solar flares
Authors: Woodgate, B. E.; Shine, R. A.; Poland, A. I.; Orwig, L. E.
Bibcode: 1983ApJ...265..530W
Altcode:
Several fast impulsive phase solar flare bursts were observed by
the Solar Maximum Mission instruments on 1980 November 8. The bursts
were seen to be coincident in the O V 1371 Å line formed at 2.5 ×
105 K and in 25-300 keV X-rays, to within the resolution
time of 1 s. This lack of time difference is inconsistent with models
for these flares in which the hard X-rays are produced at the top of
a loop, followed by the formation of a thermal conduction front which
travels to the footpoint where a UV burst is produced by heating. Models
in which both X-rays and UV radiation are produced at the footpoint,
or an electron beam transmits energy between loop top and footpoint
is less than 1 s, are allowed.
Title: Fluid motions in the solar chromosphere-corona transition
region. I - Line widths and Doppler shifts for C IV
Authors: Athay, R. G.; Gurman, J. B.; Henze, W.; Shine, R. A.
Bibcode: 1983ApJ...265..519A
Altcode:
Matrices of line profiles for C IV, λ1548, observed with a 3" aperture
and sampled in 3" intervals in active and quiet solar regions, show
a pronounced tendency for line width to increase with increasing
redshift. The correlation between increasing central intensity of the
line and increasing redshift demonstrated by some authors is clearly
present in these data but is weakened by the not infrequent occurrence
of regions of strong redshift but with low intensity. Sunspots show
both systematically narrower line profiles over umbral areas and strong
redshifts on their Sun-center side. The latter result is consistent
with a reverse Evershed effect.
Title: Observations of the Longitudinal Magnetic Field in the
Transition Region and Photosphere of a Sunspot
Authors: Henze, W., Jr.; Tandberg-Hanssen, E.; Hagyard, M. J.; West,
E. A.; Woodgate, B. E.; Shine, R. A.; Beckers, J. M.; Bruner, M.;
Hyder, C. L.; West, E. A.
Bibcode: 1982SoPh...81..231H
Altcode:
The Ultraviolet Spectrometer and Polarimeter on the Solar Maximum
Mission spacecraft has observed for the first time the longitudinal
component of the magnetic field by means of the Zeeman effect in
the transition region above a sunspot. The data presented here were
obtained on three days in one sunspot, have spatial resolutions of
10 arc sec and 3 arc sec, and yield maximum field strengths greater
than 1000 G above the umbrae in the spot. The method of analysis,
including a line-width calibration feature used during some of the
observations, is described in some detail in an appendix; the line
width is required for the determination of the longitudinal magnetic
field from the observed circular polarization.
Title: Measurements of solar transition zone velocities and line
broadening using the ultraviolet spectrometer and polarimeter on
the Solar Maximum Mission
Authors: Simon, G.; Mein, P.; Vial, J. C.; Shine, R. A.; Woodgate,
B. E.
Bibcode: 1982A&A...115..367S
Altcode:
The UVSP instrument on SMM is able to observe solar regions at two
wavelengths in the same line with a band-pass of 0.3 A. Intensity and
Doppler velocity maps are derived. It is shown that the numerical
values are sensitive to the adopted Doppler width and the range of
velocities is limited to within 30 km/sec. A method called Double
Dopplergram Determination (DDD) is described for deriving both the
Doppler width and the velocity (up to 80 km/sec), and the main sources
of uncertainties are discussed. To illustrate the method, a set of C
IV 1548 A observations is analyzed according to this procedure. The
mean C IV Doppler width measured (0.15 A) is comparable to previous
determinations. A relation is found between bright regions and
down-flows. Large Doppler widths correspond to strong velocity
gradients.
Title: Fluid motions the solar chromosphere-corona transition
region. II Active region flows in C IV from narrow slit Dopplergrams
Authors: Athay, R. G.; Gurman, J. B.; Shine, R. A.; Henze, W.
Bibcode: 1982ApJ...261..684A
Altcode:
From a study of Dopplergrams made with two narrow slits in the opposite
wings of the C IV line, N λ1548, we find widespread evidence for
steady flow patterns associated with large sunspots and, on a larger
scale, with active region magnetic field patterns. The characteristic
sunspot flow is in the reverse Evershed sense with a substantial
vertical component. Active region flows indicate oppositely directed
velocities with mainly horizontal components on either side of magnetic
neutral lines. Some neutral lines show flow toward the neutral line,
whereas others show flow away from the neutral line.
Title: Relation of Ephemeral Magnetic Regions to the Low Amplitude
Branch of Persistent Vertical Velocities
Authors: Gebbie, K. B.; Toomre, J.; Haber, D. A.; Hill, F.; Simon,
G. W.; November, L. J.; Gurman, J. B.; Shine, R. A.
Bibcode: 1982BAAS...14R.939G
Altcode: 1982BAAS...14..939G
No abstract at ADS
Title: Upflows Immediately Prior to the Impulsive Phase of Solar
Flares
Authors: Woodgate, B. E.; Shine, R. A.; Schmahl, E. J.; Kundu, M.;
Gaizauskas, V.
Bibcode: 1982BAAS...14..898W
Altcode:
No abstract at ADS
Title: Formation of the O I resonance triplet and intercombination
doublet in the solar chromosphere
Authors: Skelton, D. L.; Shine, R. A.
Bibcode: 1982ApJ...259..869S
Altcode:
Spectrum synthesis calculations are presented for the O I resonance
triplet at 1304 A and the intercombination doublet at 1358 A for
the solar atmosphere and several variants, allowing for triplet
fluorescence by the Ly-beta emission of H I. Profiles, synthesized
from a seven-level plus continuum O I atom are compared to observations
taken with the high-resolution spectrometer on OSO 8. It is found that
the O I triplet emission is dominated by the Ly-beta fluorescence and
that the agreement between observations and profiles computed with
current chromospheric models is much improved over earlier studies.
Title: Mass motions in the solar chromosphere and transition zone
Authors: Mein, P.; Simon, G.; Vial, J. C.; Shine, R. A.
Bibcode: 1982A&A...111..136M
Altcode:
A comparison is made between H-alpha and C IV observations of Active
Region 2717 on October 9, 1980. On the basis of this comparison,
it is found that upward velocities are present above sunspots in the
chromosphere-corona transition zone (20 km/s). The downward velocities
are found to be well correlated in both lines. Doppler-shift ratios
between C IV and H-alpha levels (approximately 10) are seen to be much
smaller than expected from density ratio estimates. The comparison is
seen as suggesting that flow lines are probably far from vertical in
the transition zone. It is pointed out, however, that this depends
on model densities that may not be correct. A simple method for
comparing matter flows is presented. The best fit between H-alpha and
C IV levels is obtained when C IV Doppler shifts are multiplied by
the line intensity to the power 0.5 (approximately) in order to make
allowance for density fluctuations.
Title: The Impulsive and Gradual Phases of a Solar Limb Flare as
Observed from the Solar Maximum Mission Satellite
Authors: Poland, A. I.; Machado, M. E.; Wolfson, C. J.; Frost,
K. J.; Woodgate, B. E.; Shine, R. A.; Kenny, P. J.; Cheng, C. C.;
Tandberg-Hanssen, E. A.; Bruner, E. C.; Henze, W.
Bibcode: 1982SoPh...78..201P
Altcode:
Simultaneous observations of a solar limb flare in the X-ray and
ultraviolet regions of the spectrum are presented. Temporal and
spectral X-ray observations were obtained for the 25-300 keV range
while temporal, spectral, and spatial X-ray observations were obtained
for the 30-0.3 keV range. The ultraviolet observations were images
with a 10″ spatial resolution in the lines of O v (Te
∼ 2.5 × 105 K) and Fe XXI (Te ∼ 1.1 ×
107 K). The hard X-ray and O v data indicate that the
impulsive phase began in the photosphere or chromosphere and continued
for several minutes as material was ejected into the corona. Impulsive
excitation was observed up to 30 000 km above the solar surface at
specific points in the flare loop. The Fe XXI observations indicate a
preheating before the impulsive phase and showed the formation of hot
post-flare loops. This later formation was confirmed by soft X-ray
observations. These observations provide limitations for current
flare models and will provide the data needed for initial conditions
in modeling the concurrent coronal transient.
Title: Evidence of redshifts in the average solar line profiles of
C iv and Si iv from OSO-8 observations
Authors: Roussel-Dupre, D.; Shine, R. A.
Bibcode: 1982SoPh...77..329R
Altcode:
Measurements of the C IV 1548 Å and Si IV 1393 Å lines made with the
University of Colorado Ultraviolet Spectrometer on board OSO-8 show that
the mean profiles are redshifted at disk center. Assuming these lines to
be optically thin, we measure an apparent average downflow of material
in the 50 000 to 100 000 K temperature range which is weighted by the
emission measure in these lines. The magnitude of the redshift varies
from 6-17 km s−1 with a mean of 12 km s−1
and is persistent at least on the order of months, which is the time
covered by the observations presented in this paper. Pneuman and Kopp
(1978) have demonstrated that the flux of material associated with this
downflow is of the same order of magnitude as the flux of material
being carried upward in spicules. Thus, it is possible that material
observed to be downflowing in C IV and Si IV has its origins in the
upward moving spicule material.
Title: Transition region oscillations in sunspots.
Authors: Gurman, J. B.; Leibacher, J. W.; Shine, R. A.; Woodgate,
B. E.; Henze, W.
Bibcode: 1982ApJ...253..939G
Altcode:
Time series observations of the profile of the C IV resonance
line 1548.19 A obtained in eight sunspots with the Ultraviolet
Spectrometer and Polarimeter (UVSP) on the Solar Maximum Mission are
discussed. All of the sunspots exhibit significant oscillations in
line-of-sight velocity with frequencies in the range from 5.8 mHz to
7.8 mHz (periods of 129-173 s). Significant intensity oscillations
are observed at the same periods in four of the time series; the
maximum intensity is in phase with maximum blueshift. Difference
spectroheliograms ('Dopplergrams') of the two halves of the C IV line,
as well as observations in the Si IV resonance line 1402.77 A and the
O IV intersystem line 1401.16 A, also reveal velocity oscillations at
similar frequencies but only over sunspots.
Title: Observations of solar flare transition zone plasmas from the
Solar Maximum Mission
Authors: Cheng, C. -C.; Bruner, E. C.; Tandberg-Hanssen, E.; Woodgate,
B. E.; Shine, R. A.; Kenny, P. J.; Henze, W.; Poletto, G.
Bibcode: 1982ApJ...253..353C
Altcode:
The spatial and temporal evolution of the Si IV and O IV intensity,
density and mass motions in preflare and flare transition zone plasmas
are studied for the case of the April 8, 1980 flare. It is found that:
(1) the UV flare observed in the Si IV and O IV lines is unambiguously
identified as occurring in a low-lying, preexisting transition zone loop
which spanned the magnetic neutral line separating a larger leader spot
and a newly emerged, isolated spot of opposite polarity; (2) at the
onset of the flare, the easternmost footpoint, which was anchored in
an isolated spot region of high longitudinal magnetic field gradient,
showed sudden, impulsive brightening with large intensity increases;
and (3) the release flare energy was transported by way of large-scale
connecting field lines to other parts of the active region, producing
the hot plasma and H-alpha kernels observed near the trailing spot.
Title: Impact linear polarization observed in a UV chromospheric
line during a solar flare
Authors: Henoux, J. C.; Chambe, G.; Semel, M.; Woodgate, B.; Shine,
R.; Beckers, J.
Bibcode: 1982AdSpR...2k.155H
Altcode: 1982AdSpR...2..155H
Linear polarization was observed in the S I 1437Å line in bright
flaring points during the soft X-ray emission. The degree of
polarization is about 25% and is detected at a signal to noise ratio
of 2.9. The polarized electric vector is directed towards disk center
to within 3°. This polarization could be due to collisional
excitationm of S I by energetic electrons beamed in the vertical
direction. We suggest that the heat flux in the region interconnecting
the transition zone to the high chromosphere during the gradual phase
of a flare could lead to an anisotropic excitation. Then the observed
polarization would be due to vertical motions of the transition zone
sweeping the preexisting chromosphere.
Title: Steady flows in the solar transition region observed with SMM
Authors: Gebbie, K. B.; Hill, F.; November, L. J.; Gurman, J. B.;
Shine, R. A.; Woodgate, B. E.; Athay, R. G.; Tandberg-Hanssen, E. A.;
Toomre, J.; Simon, G. W.
Bibcode: 1981ApJ...251L.115G
Altcode:
Steady flows in the quiet solar transition region have been observed
with the Ultraviolet Spectrometer and Polarimeter experiment on the
Solar Maximum Mission (SMM) satellite. The persistent vertical motions
seen at disk center have spatial rms amplitudes of 1.4 km/s in the C
II line, 3.9 km/s in Si IV, and 4.2 km/s in C IV. The amplitudes of
the more horizontal flows seen toward the limb tend to be somewhat
higher. Plots of steady vertical velocity versus intensity seen at
disk center in Si IV and C IV show two distinct branches.
Title: Spatial and temporal structures of impulsive bursts from
solar flares observed in UV and hard X-rays
Authors: Cheng, C. -C.; Tandberg-Hanssen, E.; Bruner, E. C.; Orwig,
L.; Frost, K. J.; Kenny, P. J.; Woodgate, B. E.; Shine, R. A.
Bibcode: 1981ApJ...248L..39C
Altcode:
New observations are presented of impulsive UV and hard X-rays
bursts in two solar flares obtained with instruments on Solar Maximum
Mission. The UV bursts were observed in the Si IV and O IV emission
lines, whose intensity ratio is density-sensitive. By comparing the
spatially resolved Si IV/O IV observations with the corresponding hard
X-ray observations, it is possible to study their spatial and temporal
relationships. For one flare, the individual component spikes in the
multiply peaked hard X-ray burst can be identified with different
discrete Si IV/O IV flaring kernels of size 4 arcsec x 4 arcsec or
smaller, which brighten up sequentially in time. For the other, many
Si IV/O kernels, widely distributed over a large area, show impulsive
bursts at the same time, which correlate with the main peak of the
impulsive hard X-ray burst. The density of the flaring Si IV/O IV
kernels is in the range from 5 x 10 to the 12th-13th/cu cm.
Title: Excitation of the Chlorine I Line at 1351Å
Authors: Shine, R. A.; Woodgate, B. E.; Ayres, T. R.
Bibcode: 1981BAAS...13Q.830S
Altcode:
No abstract at ADS
Title: Flare Buildup at 6 cm Wavelength, in UV and Hα
Authors: Schmahl, E. J.; Kundu, M. R.; Woodgate, B.; Shine, R.
Bibcode: 1981BAAS...13..846S
Altcode:
No abstract at ADS
Title: Observations of the 1980 April 30 limb flare by the ultraviolet
spectrometer and polarimeter on the Solar Maximum Mission
Authors: Woodgate, B. E.; Shine, R. A.; Brandt, J. C.; Chapman,
R. D.; Michalitsianos, A. G.; Kenny, P. J.; Bruner, E. C.; Rehse,
R. A.; Schoolman, S. A.; Cheng, C. C.
Bibcode: 1981ApJ...244L.133W
Altcode:
Observations of the M2 limb flare of 1980 April 30 by the ultraviolet
spectrometer and polarimeter in the C IV 1548 A line are described
and compared with observations from other SMM instruments and with
ground-based H-alpha data. Events observed during the 18 minutes leading
up to the flare impulsive phase include the filling of a small loop
with material moving at about 20 km/s, followed by a rapid brightening
in C IV, H-alpha, and hard X-rays, with a subsequent brightening of
a higher set of loops. The rapid brightening appears to be at the
junction of the small loop with the overlying magnetic structures,
which suggests the flare may be caused by their interaction.
Title: SMM/UVSP Observations of Oscillations and Other Properties
in a Sunspot
Authors: Henze, W.; Tandberg-Hanssen, E.; Reichmann, E. J.; Shine,
R. A.; Woodgate, B. E.; Gurman, J. B.; Athay, R. G.
Bibcode: 1981BAAS...13..858H
Altcode:
No abstract at ADS
Title: Height Dependence of Steady Flows Determined from Coordinated
SMM and SPO Observations
Authors: Gebbie, K. B.; Hill, F.; Toomre, J.; November, L. J.; Simon,
G. W.; Gurman, J. B.; Shine, R. A.; Woodgate, B. E.
Bibcode: 1981BAAS...13..914G
Altcode:
No abstract at ADS
Title: Solar maximum mission experiment: Ultraviolet spectroscopy
and polarimetry on the solar maximum mission
Authors: Tandberg-Hanssen, E.; Cheng, C. C.; Woodgate, B. E.; Brandt,
J. C.; Chapman, R. D.; Kenney, P. J.; Michalitsianos, A. G.; Shine,
R. A.; Athay, R. G.; Beckers, J. M.; Bruner, E. C.; Rehse, R. A.;
Schoolman, S. A.; Gurman, J. B.; Hyder, C. L.; Henze, W.
Bibcode: 1981AdSpR...1m.275T
Altcode: 1981AdSpR...1..275T
We describe the Ultraviolet Spectrometer and Polarimeter (UVSP) on the
Solar Maximum Mission (SMM) spacecraft. The instrument, which operates
in the wavelength range 1150 - 3600 Å, has a spatial resolution of 2-3
arc sec and a spectral resolution of 0.02 Å FWHM in second order. A
Gregorian telescope, focal length 1.8 m, feeds a 1 m Ebert-Fastie
spectrometer. A polarimeter comprising rotating Mg F2
waveplates can be inserted behind the spectrometer entrance slit and
allows all four Stokes parameters to be determined. The observing
modes include rasters, spectral scans, velocity measurements, and
polarimetry. Finally, we present examples of initial observations made
since launch.
Title: Solar Maximum Mission experiment: ultraviolet spectroscopy
and polarimetry on the Solar Maximum Mission.
Authors: Tandberg-Hanssen, E.; Woodgate, B. E.; Athay, R. G.; Beckers,
J. M.; Brandt, J. C.; Bruner, E. C.; Chapman, R. D.; Cheng, C. -C.;
Gurman, J. B.; Hyder, C. L.; Kenney, P. J.; Michalitsianos, A. G.;
Rehse, R. A.; Schoolman, S. A.; Shine, R. A.; Henze, W.
Bibcode: 1981hea..conf..275T
Altcode:
No abstract at ADS
Title: UVSP/SMM observations of transition region oscillations
in sunspots
Authors: Gurman, J. B.; Shine, R. A.; Woodgate, B. E.; Leibacher,
J. W.; Henze, W.
Bibcode: 1981phss.conf..319G
Altcode:
Using Ultraviolet Spectrometer and Polarimeter data obtained in emission
lines formed at temperatures of 70,000 K to 130,000 K, transition
region oscillations in sunspots have been observed. The frequency of
these oscillations lies in the range 5.8 mHz to 7.8 mHz. Their regular
appearance in line-of-sight velocity and their frequent occurrence in
intensity in phase with maximum blue shift leads to the interpretation
of the oscillations as upward-propagating acoustic waves. The presence
in two of the C IV wavelength 1548.19 time series of a phase-shifted
oscillation in the line width may be caused by the presence of
unidentified blends in the line wings. The energy flux carried by the
umbral acoustic waves is less than 2000 erg/sq cm/s, some seven orders
of magnitude smaller than the missing radiative flux of sunspots.
Title: The photospheric vector magnetic field of a sunspot and its
vertical gradient
Authors: Hagyard, M. J.; West, E. A.; Tandberg-Hanssen, E.; Smith,
J. E.; Henze, W., Jr.; Beckers, J. M.; Bruner, E. C.; Hyder, C. L.;
Gurman, J. B.; Shine, R. A.
Bibcode: 1981phss.conf..213H
Altcode:
The results of direct comparisons of photospheric and transition
region line-of-sight field observations of sunspots using the SMM UV
spectrometer and polarimeter are reported. The analysis accompanying
the data is concentrated on demonstrating that the sunspot concentrated
magnetic field extends into the transition region. An observation
of a sunspot on Oct. 23, 1980 at the S 18 E 03 location is used as
an example. Maximum field strengths ranged from 2030-2240 gauss for
large and small umbrae viewed and inclination of the field to the
line-of-sight was determined for the photosphere and transition
region. The distribution of the magnetic field over the sunspot
and variation of the line-of-sight gradient are discussed, as are
the magnitudes and gradients of the photospheric field across the
penumbral-photospheric boundaries.
Title: The Development of Flares Observed in the Spectral Lines OV
1371 Å, FeXXI 1354 Å, and in Hard X-Rays
Authors: Woodgate, B. E.; Bruner, E. C.; Cheng, C. C.; Dennis, B. R.;
Gurman, J. B.; Frost, K. J.; Hyder, C. L.; Kiplinger, A.; Mason,
H. E.; Orwig, L. E.; Poland, A. I.; Schoolman, S. A.; Shine, R. A.;
Tandberg-Hanssen, E. A.
Bibcode: 1980BAAS...12..911W
Altcode:
No abstract at ADS
Title: Steady Flows in the Solar Transition Region Observed with
the UVSP Experiment on SMM
Authors: Gebbie, K. B.; Hill, F.; Toomre, J.; November, L. J.; Simon,
G. W.; Athay, R. G.; Bruner, E. C.; Rehse, R.; Gurman, J. B.; Shine,
R. A.; Woodgate, B. E.; Tandberg-Hanssen, E. A.
Bibcode: 1980BAAS...12..907G
Altcode:
No abstract at ADS
Title: Transition Region Oscillations in Sunspots
Authors: Gurman, J. B.; Shine, R. A.; Woodgate, B. E.;
Tandberg-Hanssen, E. A.; Bruner, E. C.; Schoolman, S. A.; Athay, R. G.
Bibcode: 1980BAAS...12..906G
Altcode:
No abstract at ADS
Title: The Spatial Dependence of UV and X-Ray Phenomena Occurring
During the Impulsive Phase of a Flare
Authors: Frost, K. J.; Dennis, B. R.; Orwig, L. E.; Kiplinger, A. L.;
Leibacher, J.; Antonucci, E.; Parmar, A. N.; Woodgate, B.; Shine,
R.; Cheng, C. -C.
Bibcode: 1980BAAS...12..905F
Altcode:
No abstract at ADS
Title: SMM/UVSP Observations of Magnetic Fields in the Transition
Region above Sunspots
Authors: Henze, W.; Beckers, J. M.; Gurman, J. B.; Hyder, C. L.;
Schoolman, S. A.; Shine, R. A.; Tandberghanssen, E.; Woodgate, B. E.;
Hagyard, M. J.
Bibcode: 1980BAAS...12R.896H
Altcode:
No abstract at ADS
Title: Correlations Between UV and X-Rays for the June 29, 1980
Flare at 02:34
Authors: Shine, R. A.; Woodgate, B. E.; Dennis, B. R.; Cheng, C. C.;
Wolfson, J.; Bruner, E. C.; Hyder, C. L.
Bibcode: 1980BAAS...12Q.903S
Altcode:
No abstract at ADS
Title: UV Observations of the June 29, 1980 Flare at 18:24UT
Authors: Poland, A. I.; Woodgate, B. E.; Shine, R. A.; Frost, K. J.;
Kenny, P.; Bruner, E. C.; Wolfson, J.; Cheng, C. C.; Tandberg-Hanssen,
E. A.; Gurman, J.; Henze, W.; Machado, M.
Bibcode: 1980BAAS...12..903P
Altcode:
No abstract at ADS
Title: Sunspot Observations with the Ultraviolet Spectrometer and
Polarimeter Experiment on the Solar Maximum Mission
Authors: Gurman, J. B.; Woodgate, B. E.; Shine, R. A.; Brandt, J. C.;
Chapman, R. D.; Michalitsianos, A. G.; Kenny, P. J.; Bruner, E. C.;
Rehse, R.; Schoolman, S. A.; Cheng, C. C.; Tandberg-Hanssen, E. A.;
Athay, G. R.; Beckers, J. M.; Henze, W.; Brown, Teledyne; Hyder, C. L.
Bibcode: 1980BAAS...12..535G
Altcode:
No abstract at ADS
Title: Density Diagnostic of Solar Active Region and Flare Plasmas
from Si IV/O IV Line Ratio as Observed from SMM
Authors: Bruner, E. C.; Rehse, R.; Schoolman, S. A.; Brandt, J. C.;
Chapman, R. D.; Kenny, P. J.; Michalitsianos, A. G.; Shine, R. A.;
Woodgate, B. E.; Cheng, C. C.; Tandberg-Hanssen, E. A.; Athay, G. R.;
Beckers, J. M.; Gurman, J.; Henze, W.; Brown, Teledyne; Hyder, C. L.
Bibcode: 1980BAAS...12R.539B
Altcode:
No abstract at ADS
Title: Density diagnostic of solar active region and flare plasmas
from Si IV/O IV line ratio as observed from SMM (Solar Maximum
Mission).
Authors: Bruner, E. C.; Rehse, R.; Schoolman, S. A.; Brandt, J. C.;
Chapman, R. D.; Kenny, P. J.; Michalitsianos, A. G.; Shine, R. A.;
Woodgate, B. E.; Cheng, C. -C.; Tandberg-Hanssen, E. A.; Athay, G. R.;
Beckers, J. M.; Gurman, J. B.; Henze, W.; Hyder, C. L.
Bibcode: 1980BAAS...12..534B
Altcode:
No abstract at ADS
Title: Solar Flare and Surge Image Sequences as Seen by the
Ultraviolet Spectrometer and Polarimeter on SMM
Authors: Henze, W.; Brown, Teledyne; Brandt, J. C.; Chapman,
R. D.; Kenny, P. J.; Michalitsianos, A. G.; Shine, R. A.; Woodgate,
B. E.; Bruner, E. C.; Rehse, R.; Schoolman, S. A.; Cheng, C. C.;
Tandberg-Hanssen, E. A.; Athay, G. R.; Beckers, J. M.; Gurman, J.;
Hyder, C. L.
Bibcode: 1980BAAS...12..532H
Altcode:
No abstract at ADS
Title: The Ultraviolet Spectrometer and Polarimeter (UVSP) on the
Solar Maximum Mission and Initial Results in Polarimetry
Authors: Tandberg-Hanssen, E.; Athay, R. G.; Bruner, E. C.; Beckers,
J. M.; Brandt, J. C.; Chapman, R. D.; Cheng, C. C.; Gurman, J.;
Henze, W.; Brown, Teledyne; Hyder, C. L.; Michalitsianos, A. G.;
Shine, R. A.; Schoolman, S. A.; Woodgate, B. E.
Bibcode: 1980BAAS...12..534T
Altcode:
No abstract at ADS
Title: The Dynamics of Solar Flares and Surges as Seen at the Solar
Limb in the Transition Zone
Authors: Woodgate, B. E.; Brandt, J. C.; Chapman, R. D.; Kenny,
P. J.; Michalitsianos, A. G.; Shine, R. A.; Bruner, E. C.; Rehse, R.;
Schoolman, S. A.; Cheng, C. C.; Tandbert-Hanssen, E. A.; Athay, G. R.;
Beckers, J. M.; Gurman, J.; Henze, W.; Brown, Teledyne; Hyder, C. L.
Bibcode: 1980BAAS...12Q.535W
Altcode:
No abstract at ADS
Title: Active Region Morphology and Evolution Images from the
Ultraviolet Spectrometer and Polarimeter
Authors: Shine, R. A.; Brandt, J. C.; Chapman, R. D.; Kenny, P. J.;
Michalitsianos, A. G.; Woodgate, B. E.; Bruner, E. C.; Rehse, R.;
Schoolman, S. A.; Cheng, C. C.; Tandberg-Hanssen, E. A.; Athay, G. R.;
Beckers, J. M.; Gurman, J.; Henze, W.; Brown, Teledyne; Hyder, C. L.
Bibcode: 1980BAAS...12R.531S
Altcode:
No abstract at ADS
Title: Line formation in the solar chromosphere. II - an optically
thick region of the chromosphere-corona transition region observed
with OSO 8
Authors: Lites, B. W.; Hansen, E. R.; Shine, R. A.
Bibcode: 1980ApJ...236..280L
Altcode:
The University of Colorado ultraviolet spectrometer aboard the Orbiting
Solar Observatory 8(OSO 8) has measured self-reversed profiles of the
resonance line of C IV lamda 1548.2 at the limb passage of an active
region. The degree of the self-reversal together with the absolute
intensity of the line profile determine the electron density in the
active region at 10 to the 10th/cu cm at temperatures where the C IV
line is formed. The nonthermal component of the broadening velocity
is no more than 14km/s, and the physical thickness of an equivalent
plane-parallel slab in hydrostatic equilibrium that would give rise
to the observed line profiles is about 430 km.
Title: The ultraviolet spectrometer and polarimeter on the Solar
Maximum Mission.
Authors: Woodgate, B. E.; Tandberg-Hanssen, E. A.; Bruner, E. C.;
Beckers, J. M.; Brandt, J. C.; Henze, W.; Hyder, C. L.; Kalet, M. W.;
Kenny, P. J.; Knox, E. D.; Michalitsianos, A. G.; Rehse, R.; Shine,
R. A.; Tinsley, H. D.
Bibcode: 1980SoPh...65...73W
Altcode:
The Ultraviolet Spectrometer and Polarimeter (UVSP) on the Solar Maximum
Mission spacecraft is described, including the experiment objectives,
system design, performance, and modes of operation. The instrument
operates in the wavelength range 1150-3600 Å with better than 2 arc
sec spatial resolution, raster range 256 × 256 arc sec2,
and 20 mÅ spectral resolution in second order. Observations can be
made with specific sets of 4 lines simultaneously, or with both sides
of 2 lines simultaneously for velocity and polarization. A rotatable
retarder can be inserted into the spectrometer beam for measurement
of Zeeman splitting and linear polarization in the transition region
and chromosphere.
Title: Formation of the Solar OI Lines - Implications of an Improved
3D Branching Ratio
Authors: Skelton, D. L.; Shine, R. A.
Bibcode: 1979BAAS...11..641S
Altcode:
No abstract at ADS
Title: Pre-Flight Calibration of the Solar Maximum Mission Ultraviolet
Spectrometer and Polarimeter I. Instrumentation &Spectrometer
Performance
Authors: Michalitsianos, A. G.; Kenney, P. J.; Shine, R. A.; Woodgate,
B. E.; Bruner, E. C., Jr.; Henze, W.; Tandbaer-Hanssen, E.
Bibcode: 1979BAAS...11..447M
Altcode:
No abstract at ADS
Title: Pre-Flight Calibrations of Solar Maximum Missions Ultraviolet
Spectrometer &Polarimeter II: Polarimeter Performance
Authors: Shine, R. A.; Kenny, P. J.; Michalitsianos, A. G.; Woodgate,
B. E.; Bruner, E. C.; Rehse, R. A.; Henze, W.; Tandberg-Hanssen, E.
Bibcode: 1979BAAS...11..447S
Altcode:
No abstract at ADS
Title: Solar maximum ultraviolet spectrometer and polarimeter
Authors: Tandberg-Hanssen, E.; Woodgate, B. E.; Brandt, J. C.;
Chapman, R. D.; Hyder, C. L.; Michalitsianos, A. G.; Shine, R. A.;
Athay, R. G.; Beckers, J. M.; Bruner, E. C.
Bibcode: 1979SPIE..184..264T
Altcode:
The objectives of the UVSP experiment are to study solar ultraviolet
radiations, particularly from flares and active regions, and to measure
constituents in the terrestrial atmosphere by the extinction of sunlight
at satellite dawn and dusk. The instrument is designed to observe the
Sun at a variety of spectral and spatial resolutions in the range from
1150 to 3600 A. A Gregorian telescope with effective focal length of
1.8 m is used to feed a 1 m Ebert-Fastie spectrometer. A polarimeter
containing rotatable magnesium fluoride waveplates is included behind
the spectrometer entrance slit and will allow all four Stokes parameters
to be determined. Velocities on the Sun can also be measured. The
instrument is controlled by a computer which can interact with the data
stream to modify the observing program. The observing modes, including
rasters, spectral scans, velocity measurements, and polarimetry, are
also described along with plans for mission operations, data handling,
and analysis of the observations.
Title: Overlapping emission peaks in the solar C I multiplet at
lambda 1560 and lambda 1657.
Authors: Shine, R. A.; Lites, B. W.; Chipman, E. G.
Bibcode: 1978ApJ...224..247S
Altcode:
Observations of the C I multiplets at 1560 and 1657 A made with the
University of Colorado spectrometer on the OSO 8 satellite are presented
and compared with computed profiles for the Vernazza-Avrett-Loeser
solar atmosphere. These are optically thick emission lines formed in
the solar chromosphere that show the central reversals typical of such
lines. In each multiplet there is an interesting case of overlapping
emission peaks which shows that such peaks do not constructively combine
but instead weaken. This behavior is easily understood and reproduced
with an optically thick, non-LTE mode of formation for these lines and
is not consistent with an optically thin mechanism. We also find that
the shapes of these blends are very sensitive to the magnitude of the
nonthermal microvelocities.
Title: Line formation in the solar chromosphere. I. The C II resonance
lines observed with OSO 8.
Authors: Lites, B. W.; Shine, R. A.; Chipman, E. G.
Bibcode: 1978ApJ...222..333L
Altcode:
The temperature structure of the upper chromosphere is investigated
using center-to-limb measurements of the C II resonance lines at 1335
A from the University of Colorado spectrometer aboard OSO 8. Spectrum
synthesis of these lines shows them to be extremely sensitive to the
temperature and the physical extent of the 20,000 K plateau proposed
by Vernazza et al (1973). Hydrostatic equilibrium models of the quiet
chromosphere are computed to obtain theoretical spectra of the Lyman
lines and continuum as well as the center-to-limb behavior of the C
II lines. Good agreement is found with observations for a plateau at
16,500 K with about 25% more material than that of Vernazza et al.
Title: Analysis of the chromospheric spectrum of O I in Arcturus.
Authors: Haisch, B. M.; Linsky, J. L.; Weinstein, A.; Shine, R. A.
Bibcode: 1977ApJ...214..785H
Altcode:
The ultraviolet and near-infrared spectra of O I in Arcturus are
analyzed by a 15-level 14-transition model for O I and the Ayres-Linsky
(1975) model chromosphere. It is found that the anomalously bright O
I resonance lines at 1302, 1305, and 1306 A can be readily explained
by a Ly-beta-pumped fluorescence mechanism as originally proposed by
Bowen (1974). Observed equivalent widths of the near-infrared triplet
and singlet lines are also consistent with the model predictions,
but the intercombination lines at 1355 and 1359 A and near-infrared
quintet lines may pose a problem.
Title: Center-to-Limb Profiles and Spatial Variations of SiII and
FeII Lines in the Solar EUV.
Authors: Shine, R. A.; Lites, B. W.
Bibcode: 1977BAAS....9R.325S
Altcode:
No abstract at ADS
Title: Solar Prominence Line Profiles Observed in the Ultraviolet
from OSO-8.
Authors: Hansen, E. R.; Schaffner, S. V. H.; Shine, R. A.; Orrall,
F. Q.
Bibcode: 1977BAAS....9..314H
Altcode:
No abstract at ADS
Title: Formation of the Solar OI Lines at λ13 and λ1355.
Authors: Skelton, D. L.; Shine, R. A.
Bibcode: 1977BAAS....9Q.325S
Altcode:
No abstract at ADS
Title: Erratum: "Evidence for a corona of Beta Geminorum"
[Astrophys. J., Lett., Vol. 193, p. L107 - L110 (1974)].
Authors: Gerola, H.; Linsky, J. L.; Shine, R.; McClintock, W.; Henry,
R. C.; Moos, H. W.
Bibcode: 1977ApJ...218L..32G
Altcode:
No abstract at ADS
Title: Preliminary results from the Orbiting Solar Observatory 8:
transition-zone dynamics over a sunspot.
Authors: Bruner, E. C., Jr.; Chipman, E. G.; Lites, B. W.; Rottman,
G. J.; Shine, R. A.; Athay, R. G.; White, O. R.
Bibcode: 1976ApJ...210L..97B
Altcode:
No abstract at ADS
Title: Preliminary results from the Orbiting Solar Observatory 8:
velocities in the solar chromosphere observed in the Si II lambda
1816 line.
Authors: Chipman, E. G.; Bruner, E. C., Jr.; Shine, R. A.; Lites,
B. W.; Rottman, G. J.; Athay, R. G.; White, O. R.
Bibcode: 1976ApJ...210L.103C
Altcode:
No abstract at ADS
Title: Preliminary results from the Orbiting Solar Observatory 8:
observations of optically thin lines.
Authors: Shine, R. A.; Roussel-Dupre, D.; Bruner, E. C., Jr.; Chipman,
E. G.; Lites, B. W.; Rottman, G. J.; Athay, R. G.; White, O. R.
Bibcode: 1976ApJ...210L.107S
Altcode:
The University of Colorado spectrometer aboard OSO 8 has measured
the high temperature C IV resonance lines (at 1548 and 1551 A) and
the Si IV resonance lines (at 1393 and 1402 A) formed in the solar
chromosphere-corona transition region. Preliminary results include
studies of mean profiles, a comparison of cell and network profiles,
and the behavior of the lines at the extreme solar limb.
Title: Preliminary results from the Orbiting Solar Observatory 8:
persistent velocity fields in the chromosphere and transition region.
Authors: Lites, B. W.; Bruner, E. C., Jr.; Chipman, E. G.; Shine,
R. A.; Rottman, G. J.; White, O. R.; Athay, R. G.
Bibcode: 1976ApJ...210L.111L
Altcode:
No abstract at ADS
Title: Analysis of OSO-8 Measurements of the Center-to-Limb Behavior
of Solar CII Line Profiles.
Authors: Lites, B. W.; Shine, R. A.
Bibcode: 1976BAAS....8..501L
Altcode:
No abstract at ADS
Title: Resonance-line transfer with partial
redistribution. VIII. Solution in the comoving frame for moving
atmospheres.
Authors: Mihalas, D.; Shine, R. A.; Kunasz, P. B.; Hummer, D. G.
Bibcode: 1976ApJ...205..492M
Altcode:
The effects of partial frequency redistribution in the scattering
process for lines formed in moving atmospheres are analyzed using a
general method that allows the transfer equation to be solved in the
comoving frame of the gas. The same chromospheric and atomic model
studied by Cannon and Vardavas (1974) is employed in the calculations,
but a depth scale with logarithmically spaced points is adopted. It is
found that in both static and moving atmospheres, the profiles obtained
with complete and partial frequency redistribution are virtually
identical. The large differences in profiles obtained by Cannon and
Vardavas when they used complete and partial redistribution are shown
to be spurious (and physically unreal) effects resulting from angle
averaging in the observer's frame instead of the comoving frame.
Title: Periodic Fluctuations in the Solar Transition Zone
Authors: Bruner, E. C., Jr.; Chipman, E. G.; Shine, R. A.; Lites,
B. W.; Rottman, G. J.; Orrall, F. Q.; Athay, R. G.; White, O. R.
Bibcode: 1976BAAS....8Q.313B
Altcode:
No abstract at ADS
Title: Model Calculations of Chromospheric Lines Observed by OSO-8
Authors: Shine, R. A.; Lites, B. W.; Chipman, E. G.; Rousel-Dupree,
D.; Bruner, E. C., Jr.; Rottman, G. J.; Orrall, F. Q.; Athay, R. G.;
White, O. R.
Bibcode: 1976BAAS....8..331S
Altcode:
No abstract at ADS
Title: Velocities in the Solar Chromosphere Observed in the CII
λ1336 Line
Authors: Chipman, E. G.; Bruner, E. C., Jr.; Shine, R. A.; Lites,
B. W.; Rottman, G. J.; Orrall, F. Q.; White, O. R.; Athay, R. G.
Bibcode: 1976BAAS....8..312C
Altcode:
No abstract at ADS
Title: OSO-8 Observations of Mean Vertical Motions in the Solar
Transition Region
Authors: Roussel-Dupree, D. C.; Shine, R. A.; Chipman, E. G.; Bruner,
E. C., Jr.; Lites, B. W.; Rottman, G. J.; Orrall, F. Q.; Athay, R. G.;
White, O. R.
Bibcode: 1976BAAS....8..312R
Altcode:
No abstract at ADS
Title: An Analysis of the Chromospheric O I Lines in Arcturus
Authors: Haisch, B. M.; Linsky, J. L.; Weinstein, A.; Shine, R.
Bibcode: 1976BAAS....8..303H
Altcode:
No abstract at ADS
Title: Short Period Chromospheric Oscillations Observed with OSO-8
Authors: Athay, R. G.; White, O. R.; Bruner, E. C., Jr.; Chipman,
E. G.; Lites, B. W.; Shine, R. A.; Orrall, F. Q.
Bibcode: 1976BAAS....8..312A
Altcode:
No abstract at ADS
Title: Supergranulation Velocity Fields Observed in the Solar
Transition Region with OSO-8
Authors: November, L. J.; Toomre, J.; Gebbie, K. B.; Simon, G. W.;
Bruner, E. C., Jr.; Chipman, E. G.; Lites, B. W.; Shine, R. A.;
Orrall, F. Q.; Athay, R. G.; White, O. R.
Bibcode: 1976BAAS....8..311N
Altcode:
No abstract at ADS
Title: Repetitive Brightenings in Active Region Transition Zone
Lines as Observed with OSO-8
Authors: Lites, B. W.; Hansen, E. R.; Shine, R. A.; Chipman, E. G.;
Bruner, E. C., Jr.; Orrall, F. Q.; Athay, R. G.; White, O. R.; Rottman,
G. J.
Bibcode: 1976BAAS....8Q.331L
Altcode:
No abstract at ADS
Title: The effect of intermediate-scale motions on line formation.
Authors: Shine, R. A.
Bibcode: 1975ApJ...202..543S
Altcode:
The problem of LTE and non-LTE line formation in the presence
of nonthermal velocity fields with geometric scales between the
microscopic and macroscopic limits is investigated in the cases of
periodic sinusoidal and sawtooth waves. For a fixed source function
(the LTE case), it is shown that time-averaged line profiles progress
smoothly from the microscopic to the macroscopic limits as the geometric
scale of the motions increases, that the sinusoidal motions produce
symmetric time-averaged profiles, and that the sawtooth motions cause
a redshift. In several idealized non-LTE cases, it is found that
intermediate-scale velocity fields can significantly increase the
surface source functions and line-core intensities. Calculations are
made for a two-level atom in an isothermal atmosphere for a range of
velocity scales and non-LTE coupling parameters and also for a two-level
atom and a four-level representation of Na I line formation in the
Harvard-Smithsonian Reference Atmosphere (1971) solar model. It is
found that intermediate-scale velocity fields in the solar atmosphere
could explain the central intensities of the Na I D lines and other
strong absorption lines without invoking previously suggested high
electron densities.
Title: Diffusion effects on the line intensities of He I and He II
in the solar transition region.
Authors: Shine, R.; Gerola, H.; Linsky, J. L.
Bibcode: 1975ApJ...202L.101S
Altcode:
A heuristic treatment of diffusion in the solar chromosphere-corona
transition region is developed. It is shown that diffusion becomes
increasingly important with steeper temperature gradients, in active and
quiet regions relative to coronal holes, and with increasing excitation
potential. Numerical calculations are made for the resonance lines of
He I and He II and show that diffusion can enhance these lines. Thus
the helium lines may appear relatively weak in coronal holes due to a
weakening of the enhancement mechanism. Most transition region lines
will be less affected by diffusion than He I or He II.
Title: An Archetype Hydrogen Atmosphere Problem
Authors: Athay, R. G.; Mihalas, D.; Shine, R. A.
Bibcode: 1975SoPh...45...15A
Altcode:
Populations for the first three bound states and the continuum of
hydrogen are determined for an isothermal, hydrostatic atmosphere at 20
000 K. The atmosphere is treated as being optically thin in the Balmer
and Paschen continua and illuminated by continuum radiation at these
wavelengths with prescribed radiation temperatures. The atmosphere is
optically thick in the 2-1, 3-1, 3-2 and c-1 transitions. Three stages
of approximation are treated: radiative detailed balance in the 2-1,
3-1 and 3-2 transitions,
Title: Resonance-line transfer with partial
redistribution. VII. Angle-dependent redistribution.
Authors: Milkey, R. W.; Shine, R. A.; Mihalas, D.
Bibcode: 1975ApJ...202..250M
Altcode:
A method is presented for treating radiative transfer in resonance
lines, allowing for the full angle and frequency dependence of
redistribution in the scattering process, as seen in the laboratory
frame. The case of an equivalent-two-level-atom source function
is considered; the problem to be treated is then linear in the
radiation field. We apply this method to the Ca II lines in the
solar atmosphere, using a redistribution function which takes into
account a mixture of coherence in the atom's frame, with Doppler
redistribution in the laboratory frame (for atoms which have not
suffered an elastic collision), and of complete redistribution in the
laboratory frame (for atoms that are collisionally perturbed during the
emission process). Both the angle-averaged approximation and the full
angle-dependent solution were obtained, and were compared to assess,
differentially, the effects of angular redistribution upon the computed
line profile and its center-to-limb behavior. For the Ca II line in a
homogeneous solar chromosphere the angle-dependent effects are found to
be negligible, indicating that one may use angle-averaged redistribution
functions when studying partial redistribution effects in line profiles.
Title: Resonance line transfer with partial redistribution. VI. The
Ca II K-line in solar-type stars.
Authors: Shine, R. A.; Milkey, R. W.; Mihalas, D.
Bibcode: 1975ApJ...201..222S
Altcode:
Using model atmospheres for solar-type stars based on scaled
temperature distributions, we discuss the effects of partial frequency
redistribution on the Ca ii K-line profiles. We show that the partial
redistribution calculations lead to a significantly lower intensity
at K1 than given by calculations based on the assumption of complete
redistribution. This implies that fits to observed fluxes with
complete redistribution calculations could tend to underestimate
systematically the value of the temperature at the chromospheric
temperature minimum. Subject headings: chromospheres, stellar - line
formation - radiative transfer
Title: High Resolution Spectroscopy From Orbiting Solar Observatory
VIII: Transition Zone Dynamics Over a Sunspot
Authors: Bruner, E. C., Jr.; Chipman, E. G.; Lites, B. W.; Rottman,
G. J.; Shine, R. A.; Athay, R. G.; White, O. R.
Bibcode: 1975BAAS....7..522B
Altcode:
No abstract at ADS
Title: Persistent Velocity Fields in the Middle Chromosphere
Authors: Lites, B. W.; Bruner, E. C., Jr.; Chipman, E. G.; Shine,
R. A.; Rottman, G. J.; White, O. R.; Athay, R. G.
Bibcode: 1975BAAS....7..522L
Altcode:
No abstract at ADS
Title: Velocities in the Solar Chromosphere Observed in the Si II
λ1816 Line
Authors: Chipman, E. G.; Bruner, E. C., Jr.; Shine, R. A.; Lites,
B. W.; Rottman, G. J.; White, O. R.; Athay, R. G.
Bibcode: 1975BAAS....7..522C
Altcode:
No abstract at ADS
Title: OSO-8 Observations of Optically Thin Lines
Authors: Shine, R. A.; Rousell-Dupree, D.; Bruner, E. C., Jr.; Chipman,
E. G.; Lites, B. W.; Rottman, G. J.; Athay, R. G.; White, O. R.
Bibcode: 1975BAAS....7Q.552S
Altcode:
No abstract at ADS
Title: Resonance line transfer with partial redistribution. IV. A
generalized formulation for lines with common upper states.
Authors: Milkey, R. W.; Shine, R. A.; Mihalas, D.
Bibcode: 1975ApJ...199..718M
Altcode:
A generalized formulation is given for treating partial redistribution
effects in transfer problems in resonance lines with common upper
states. The formulation allows explicitly for the possibility that
several spectral lines may arise in transitions from a given upper
level to several sharp lower levels, including, for example, the
ground state and metastable states. Line profiles for the Ca II H and
K lines have been calculated, accounting for the partial frequency
coherence of scattered photons. These profiles are compared with
calculations made with identical atomic and atmospheric models but
assuming complete redistribution. Very significant differences between
the profiles obtained using these two different physical descriptions
of the scattering process are found, and it is now apparent that the
assumption of complete redistribution is a serious oversimplification
of the actual physical situation. The results question the validity of
equating brightness temperatures observed at K1 in stellar
spectra with minimum temperatures in stellar chromospheres; it appears
likely that such a procedure will systematically underestimate the
value of T-min.
Title: Resonance Line Transfer with Partial Redistribution. V. The
Solar CA II Lines
Authors: Shine, R. A.; Milkey, R. W.; Mihalas, Dimitri
Bibcode: 1975ApJ...199..724S
Altcode:
Line profiles for the Ca II H and K lines have been calculated,
accounting for the partial frequency coherence of scattered
photons. These profiles are compared with calculations made with
identical atomic and atmospheric models but assuming complete
redistribution. Very significant differences between the profiles
obtained using these two different physical descriptions of the
scattering process are found, and it is now apparent that the
assumption of complete redistribution is a serious oversimplification
of the actual physical situation. The partial sredistribution (PRD)
results are in substantially better agreement with observation
than the complete redistribution (CRD) profiles in describing (a)
the center-to-limb behavior of the intensity at K1 and K2, (b) the
center-to-limb behavior of the wavelength positions of K1 and K2,
and (c) the relative behavior of the H and K profiles, as a function
of wavelength, at disk center. Further, we find that we may match
the observed absolute intensity at K1 with a minimum chromospheric
electron temperature of about 4450 K, and that the HSRA temperature
minimum is too low when partial redistribution effects are taken into
account. This result raises questions about the validity of equating
brightness temperatures observed at K1 in stellar spectra with minimum
temperatures in stellar chromospheres; it appears likely that such a
procedure will systematically underestimate the value of Tmin. Subject
headings: chromosphere, solar - line formation - radiative transfer
Title: Resonance line transfer with partial redistribution. III. Mg
II resonance lines in solar-type stars.
Authors: Milkey, R. W.; Ayres, T. R.; Shine, R. A.
Bibcode: 1975ApJ...197..143M
Altcode:
We discuss the gravity dependence of the Mg II resonance lines
calculated with inclusion of effects of partial redistribution in
frequency. Using chromospheric models scaled from a solar model, we
demonstrate the increased decoupling of the radiation temperature of
the k1 feature from the minimum electron temperature in lower-gravity
models. The limb darkening of the k-line in the main-sequence model
is also discussed.
Title: Stellar Upper Photosphere Models Based on the Ca II
K-wing. II. The Coherent Scattering Approximation
Authors: Ayres, T. R.; Linsky, J. L.; Shine, R. A.
Bibcode: 1975BAAS....7..359A
Altcode:
No abstract at ADS
Title: Calculations of Profiles for the CaII H and K Lines Including
Partial Redistribution Effects
Authors: Shine, R. A.; Milkey, R. W.; Mihalas, D.
Bibcode: 1975BAAS....7Q.360S
Altcode:
No abstract at ADS
Title: Diffusion Effects on Line Intensities in the Solar Transition
Region
Authors: Gerola, H.; Shine, R. A.
Bibcode: 1975BAAS....7..366G
Altcode:
No abstract at ADS
Title: A possible width-luminosity correlation of the Ca II
K1 and Mg II k1 features.
Authors: Ayres, T. R.; Linsky, J. L.; Shine, R. A.
Bibcode: 1975ApJ...195L.121A
Altcode:
Existing high resolution stellar profiles of the Ca II and Mg II
resonance lines suggest a possible width-luminosity correlation of the
K1 minimum features. It is shown that such a correlation can be simply
understood if the continuum optical depth of the stellar temperature
minimum is relatively independent of surface gravity as suggested by
three stars studied in detail.
Title: Evidence for a Corona of Beta Geminorum
Authors: Gerola, Humberto; Linsky, Jeffrey L.; Shine, Richard;
McClintock, W.; Henry, R. C.; Moos, H. W.
Bibcode: 1974ApJ...193L.107G
Altcode:
A spectrometer was used on the satellite Copernicus to observe a
chromospheric L alpha emission from the K0 giant beta Gem at 1218.4
A. This emission appears to be in the corona at temperatures near
260,000 deg K, since the ion it is identified with requires 77.4 eV
to be produced.
Title: Physical Properties of Solar Chromospheric Plages. II:
Chromospheric Plage Models
Authors: Shine, R. A.; Linsky, J. L.
Bibcode: 1974SoPh...39...49S
Altcode:
We propose chromospheric models of plages to explain profiles of
the Ca II H, K, λl8498, λ8542, and λ8662 lines described in Paper
I. These models are consistent with boundary conditions imposed by
the photosphere and the Lyman continuum. We find that increasing
emission in these lines is consistent with a picture of increasing
temperature gradient in the low chromosphere and the resulting increase
in pressure and electron density at similar line optical depths. With
this picture we suggest how to empirically determine the distribution
of chromospheric parameters across the solar disk directly from Ca
II filtergrams. We also propose that the high density aspects of
solar activity are produced by steep temperature gradients in the low
chromosphere and thus by the enhanced heating mechanisms that steepen
these gradients.
Title: An Upper Photosphere Model for Arcturus (K2 III) Based on
Partial Redistribution and the Ca II K-line Inner Wings
Authors: Ayers, T. R.; Linsky, J. L.; Shine, R. A.
Bibcode: 1974BAAS....6..457A
Altcode:
No abstract at ADS
Title: Stellar Model Chromospheres. H. Procyon (F5 Iv/v)
Authors: Ayres, Thomas R.; Linsky, Jeffrey L.; Shine, Richard A.
Bibcode: 1974ApJ...192...93A
Altcode: 1974ApJ...192...95A
No abstract at ADS
Title: A facular model based on the wings of the Ca ii lines
Authors: Shine, Richard A.; Linsky, Jeffrey L.
Bibcode: 1974SoPh...37..145S
Altcode:
We develop a relatively simple procedure for deriving models of upper
photospheric regions based on the damping wings of the Ca II resonance
and infrared triplet lines. The procedure is used to derive a facular
model but can also be applied to late-type stars. We compare our model
to that of Chapman.
Title: Evidence for a Corona of β Geminorum with the "Copernicus"
Satellite.
Authors: McClintock, W.; Linsky, J.; Gerola, H.; Shine, R.; Henry,
R. C.; Moos, H. W.
Bibcode: 1974BAAS....6..315M
Altcode:
No abstract at ADS
Title: Physical Properties of the Chromospheric-Corona Transition
Region Based on OSO-VI Data
Authors: Shine, R. A.; Gerola, H.
Bibcode: 1974BAAS....6..346S
Altcode:
No abstract at ADS
Title: Non-LTE Line Formation in the Presence of Intermediate Scale
Velocity Fields
Authors: Shine, R. A.
Bibcode: 1974BAAS....6S.294S
Altcode:
No abstract at ADS
Title: Line Profiles and Turbulence Generated by Acoustic Waves in
the Solar Chromosphere. II. Contours of the Ca II and Mg II K Lines
Authors: Shine, Richard A.; Oster, Ludwig
Bibcode: 1973A&A....29....7S
Altcode:
No abstract at ADS
Title: One- and Multi-Component Models of the Upper Photosphere
Based on Molecular Spectra. I: The Violet System of CN(0,0)
Authors: Mount, George H.; Linsky, Jeffrey L.; Shine, Richard A.
Bibcode: 1973SoPh...32...13M
Altcode:
Spectroheliograms taken in the CN(0, 0) violet band near λ 3883
Å show very small scale network and cell structures with high
contrast. The bandhead itself, which is a broad feature due to
overlap of several CN lines, allows the diagnostic simplicity of a
continuum since motions, magnetic fields, and broadening mechanisms
are unimportant. We have obtained spectroheliograms in the bandhead
and center-to-limb photoelectric spectra of CN(0, 0) at Kitt Peak
National Observatory. From the photoelectric spectra and a detailed
analysis of the formation of the CN(0, 0) spectrum we derive a best-fit
one-component upper photospheric model differing from that of the
HSRA and recommend a change in solar carbon abundance from the HSRA
value of logAc = 8.55 to logAc = 8.25. From the
calibrated spectroheliograms we consider a multi-component model to
account for the observed fine structure intensity variations.
Title: Photospheric Models Based on the Wings of the Ca II Lines.
Authors: Shine, R. A.; Ayres, T. R.
Bibcode: 1973BAAS....5..453S
Altcode:
No abstract at ADS
Title: A simple explanation of the Wilson-Bappu effect.
Authors: Ayres, T. R.; Linsky, J. L.; Shine, R. A.; Chipman, E.
Bibcode: 1973BAAS....5..364A
Altcode:
No abstract at ADS
Title: The Effect of Small and Large Scale Sine Waves upon
Chromospheric Line Profiles
Authors: Shine, Richard; Oster, Ludwig
Bibcode: 1973BAAS....5T.279S
Altcode:
No abstract at ADS
Title: On the dependence of the two-levelsource function on its own
radiation field.
Authors: Steinitz, Raphael; Shine, Richard A.
Bibcode: 1973MNRAS.162..197S
Altcode:
The consequences of the universally made assumption that the
stimulated emission profile is identical to the absorption profile
are quantitatively investigated for a two-level atom with Doppler
redistribution. The nonlinear terms arising in the source function are
evaluated iteratively. We find that the magnitude of the effects are
governed by = (hv/kT - I)-' and are probably completely
negligible for visible and UV solar lines. For = 2 effects of 5 per
cent are encountered. Larger `s lead to numerical instabilities in
the method of solution used.
Title: Physical Properties of Solar Plages.
Authors: Shine, Richard Alan
Bibcode: 1973PhDT........22S
Altcode:
No abstract at ADS
Title: Discovery of upper photospheric temperature inversions or
chromospheres in early A stars.
Authors: Linsky, J. L.; Shine, R. A.; Ayres, T. R.; Praderie, F.
Bibcode: 1973BAAS....5....3L
Altcode:
No abstract at ADS
Title: Discovery of Chromospheres in Early A Stars.
Authors: Linsky, J. L.; Shine, R. A.; Ayres, T. R.; Praderie, F.
Bibcode: 1973BAAS....5R...3L
Altcode:
No abstract at ADS
Title: Physical Properties of Solar Chromospheric Plages. I. Line
Profiles of the Ca II H, K, and Infrared Triplet Lines
Authors: Shine, Richard A.; Linsky, Jeffrey L.
Bibcode: 1972SoPh...25..357S
Altcode:
Double pass photoelectric observations are presented of five CaII lines
(H, K, 8498 Å, 8542 Å, and 8662 Å) in a number of solar plages of
different degrees of activity, quiet regions, and a sunspot. The data
are compared with previous work. All five lines show increasing emission
together in plages and the least opaque of the infrared triplet lines
appears to exhibit core emission prior to the more opaque members of
the multiplet. The question of source function equality is considered
and the differences and similarities among plage profiles and between
plage and quiet profiles are shown qualitatively and quantitatively.
Title: Photoelectric Ca II Line Profiles in Solar Plages and a
Sunspot and Their Preliminary Interpretation
Authors: Shine, Richard A.; Linsky, Jeffrey L.
Bibcode: 1972BAAS....4T.391S
Altcode:
No abstract at ADS