| Title |
Name |
Institute |
Abstract Title |
Abstract |
| Dr | Alan Gabriel | IAS,, Université Paris II, Orsay, France | | |
| Dr | Alessandra Giunt | RAL | | null |
| Dr | Andrzej Fludra | STFC Rutherford Appleton Laboratory | | |
| Mr | Anton Reva | Lebedev Physical Institute | Anomalous intensity ratio of Ly-alpha doublet hydrogen-like ion Mg XII 8.42 A in hot compact objects of the solar corona. | Spectroheliograph Mg XII on the CORONAS-F satellite is
an instrument which builds images of the solar corona
in Ly-alpha line of hydrogen-like ion Mg XII 8.42 A.
Features of spectroheliograph structure allow obtain
spectrum of a doublet for compact hot objects. We
investigated 169 flare-like objects, which were
observed from between 20 February 2002 and 28 February
2002. Lifetime of these objects is around 2 minutes ?
3 hours, size less than 5 Mm, average temperature ? 10
MK, their intensity is below GOES A class. Intensity
ratio of doublet components in these flare-like events
is changing during their lifetime in the range 0,3 ?
0,7. Theoretical value is 0.5. Histogram of the ratio
is symmetrical ? low values are met as often as high
values. Proposed theoretical mechanism (proton
excitation, satellites lines, resonance scattering)
can?t explain experimental data. |
| Dr | Arkadiusz Berlicki | Astronomical Institute, Academy of Sciences, Czech Republic | Multi-wavelength spectroscopy of a white-light flare | A. Berlicki, P. Heinzel, J. Kasparova, M. Sobotka, M. Karlicky, A. Garcia Multi-wavelength observations of o white-light flare (WLF) have been performed on August 9, 2011 close to the solar limb. We present an overview of the observational data, basic characteristics of the flare evolution (the H-alpha movie), and possible mechanisms of the WLF emission. The flare optical emission was observed around the H-alpha line with the Coimbra spectroheliograph. Luckily, the slit of the Coimbra spectroheliograph crossed the flare ribbons around the moment of the flare maximum. We clearly observe the continuum emission at +/- 15 A from the line centre, which is certainly not due to extended wings of the H-alpha line. We performed the absolute calibration of the optical spectra and study possible mechanisms of such continuous emission. We also present other observations of this event (RHESSI, SDO/AIA, SDO/EVE, radio-microwave) and use them to find the spatial and time correlations between the white-light emission and non-thermal electron bombardment of the chromosphere. |
| Dr | Bart De Pontieu | Lockheed Martin Solar & Astrophysics Laboratory | Observations and Modeling of the Chromosphere-Corona Connection | I will review recent
observations and
numerical modeling
of the connection
between the
chromosphere and
corona, focusing on
two phenomena,
spicules and Alfven
waves, that have
recently been
implicated in the
mass and energy
transfer between the
low atmosphere and
corona. I will
discuss the
potential role of
spicules in
explaining
spectroscopic
observations of
Doppler shifts, line
broadening and line
asymmetries in the
transition region
and corona. I will
also review the
intimate coupling
between both
phenomena, and
describe how to
reconcile
spectroscopic and
imaging observations
of Alfven waves in
the corona. |
| Mr | Brendan O Dwyer | University of Cambridge | Observations of Active Region Evolution | B. O Dwyer, D.
Tripathi, H. E.
Mason
We examine the
evolution of active
regions NOAA 11057
and NOAA 11193 over
the course of a
solar rotation,
using simultaneous
observations from
Hinode EIS and SDO
AIA. Emission
measure analyses are
carried out in the
core of both active
regions in order to
investigate
variations in
temperature
structure as the
active regions
evolve. |
| Dr | Brian C. Fawcett. | Retired from Rutherford Appleton Laboratory. | History and highlights of the identification of Solar Flare Spectra of Fe XVIII-Fe XXVI and other ions. | History and highlights of the identification of Solar
Flare Spectra of Fe XVIII-Fe XXVI and other ions.
B. C. Fawcett: Retired from Rutherford Appleton
Laboratory.
Before solar flare diagnosis could start it was
necessary to identify solar flare lines. No crystal
soft X-ray solar spectra were available until a Naval
Research Laboratory rocket flight of 1963. The first
flare line of Fe XVIII was retrieved with a
University College London/Leicester University rocket
payload in 1966. George Doschek took part in the
analysis of solar flare spectra after he joined the
Naval research Laboratory in 1968. He studied
satellite spectra acquired from NRL's instruments on OSO IV and OSO VI and
later from SKYLAB and P 78-1 in which NRL participated.
To respond to the urgent need for atomic structure
flare line classifications, research using laser
produced plasmas and other light sources was
undertaken at NRL. This program was closely related
to research, firstly conducted at Culham and then at
RAL. International laboratories joined in the race
with both ground based and satellite projects such
as: OVI-10, 7, OSO 3, 5, 7 and intercosmos. By the
time the line lists became available from P 78-1 in
1980&85 and Solar Maximum Mission in 1982&87 the main
flare line identifications essential for solar
spectroscopy were documented. Parallel grazing
incidence studies contributed new solar flare allowed
and forbidden line identifications.
This presentation describes the critical atomic
structure analysis involved and highlights
information of special interest. After this
successful research the teams moved on in the late
1980,s to participate, across Pacific as well as the
Atlantic, in great space projects, such as those
presented at this Conference, which often rely on
these line identifications.
|
| Dr | Brigitte Schmieder | Observatoire de Paris, LESIA | Spectroscopic diagnostics for prominence | Schmieder B.,
Heinzel P., Gunar
S., Mein P.,
Labrosse, N.,
Berlicki A.
The dynamics of
prominence fine
structures is a
challenge to
understand the
formation of cool
plasma prominence
embedded in the hot
corona.
The observations of
fine structures
obtained by
different
spectrographs on the
ground (MSDP/Meudon)
and in space
(Hinode/EIS,
SOHO/SUMER) combined
with 2D non ?LTE
radiative transfer
code allow us to
study the bulk
velocities in these
structures.
The Dopplershifts of
bright threads
measured by the
MSDP spectrograph of
a hedge-row
prominence observed
by Hinode/SOT are
of the same order
of magnitude larger
than the velocities
perpendicular to the
line-of-sight .
This statement
suggests that the
vertical structures
shown in SOT movies
are not real
vertical magnetic
structures but a
pile up of dips
along horizontal
field lines.
Thermal
characteristics of
the plasma in
prominence and its
environment are
derived from the
study of hydrogen
Lyman lines and
transition region
lines using SUMER .
Hinode/EIS give
some insight of the
bubble??
temperature below
prominences. The
rise of the bubble
would be due more to
magnetic instability
than thermal effect.
|
| Prof | Carole Jordan | University of Oxford | Emission line profiles in solar and stellar ultraviolet spectra | Carole Jordan
The profiles of uv
emission lines yield
important
information on line
broadening and
velocity fields, and
have been studied,
with increasing
accuracy, since the
early days of solar
observations from
space. The spectra
of quiet solar
regions, from the
chromosphere to the
corona (including
density-sensitive
lines), allow
constraints to be
placed on the
non-thermal energy
densities and fluxes
associated with
processes that might
heat the quiet
corona. The Space
Telescope Imaging
Spectrograph on the
Hubble Space
Telescope provides
the highest quality
uv spectra
available, although
for spatially
integrated emitting
regions. For both
solar and stellar
sources, line shifts
and two-component
profiles are
observed, which
further
constrain processes
present. While
stellar sources give
dependencies on
properties such as
the surface gravity,
effective
temperature and
rotation period,
solar observations
above the limb
provide the only
means of
examining the high
corona where energy
dissipation is
most likely to
occur. |
| Dr | Costis Gontikakis | Research Center for Astronomy and Applied Mathematics, Academy of Athens | Study of flows and the three-dimensional shape of coronal loops observed by Hinode/EIS. | Authors: C. Gontikakis, P. Syntelis, M.K. Georgoulis, C.E. Alissandrakis, and K. Tsinganos
Abstract text : We study plasma flows along selected coronal loops in NOAA Active Region 10926, observed on December 3, 2006 with Hinode EUV Imaging Spectrograph (EIS). From the shape of the loops traced on intensity images and the Doppler shifts measured along their length we compute their three-dimensional (3D) shape and plasma flow velocity using a simple geometrical model. This calculation was performed for loops visible in the Fe VIII 185A, Fe X 184A, Fe XII 195A, Fe XIII 202A, and Fe XV 284A spectral lines. For the 6 loops, studied in 16 different images, we find cases with unidirectional flows and also cases of draining motions from the loops' top to their footpoints. Our results indicate that the same loop may show different flow patterns when observed in different spectral lines, suggesting dynamically complex rather than monolithic structures. We have also carried out magnetic field extrapolations using SOHO/MDI magnetograms, aiming toward a first-order identification of extrapolated magnetic field lines corresponding to the reconstructed loops. In all cases, the best-fit extrapolated lines exhibit left-handed twist, in agreement with the dominant twist of the region. |
| Dr | David Brooks | George Mason University | | |
| Dr | David Long | MSSL/UCL | | |
| Mr | David Shelton | UCL/MSSL | The onset of outflows in NOAA 11117 using SDO | D.Shelton, L.Harra, L.Green
Coronal outflows have been observed using EUV imaging
on TRACE. However, it has only been since the launch
of Hinode that direct spectroscopic detection of
persistent outflows have been made using the EUV
Imaging Spectrometer
These persistent outflows have larger speeds in
spectral lines that are formed at T > 1 MK, they are
found at the edges of active regions and are unchanged
over a long period of time. It has been suggested that
these persistent outflows could be caused by
chromospheric evaporation flow magnetic reconnection
and that the outflows could be related to the origin
of the slow solar wind. EIS observations show that
these outflows are associated with ?open? coronal
magnetic field lines. It has recently been shown that
emerging flux into an active region can produce new
and enhanced outflows. which have been shown through
simulations to be caused by a mixture of compression
and magnetic reconnection.
In this work, we choose an example of a region that
emerged into quiet Sun and not into a pre-existing
active region. We present the results of a study using
the Solar Dynamics Observatory (SDO) of the emergence
of active region NOAA 11117 which was present on the
solar disk between 21st October and 31st October 2010.
By using the high spatial resolution and high temporal
cadence of SDO, we are able to determine when in the
formation of the active region that the onset of these
persistent outflows started. The outflows were delayed
by 3 and a half days from the region s first
emergence. By comparing the AIA 171 Angstrom data with
the HMI magnetogram data for this period, we see that
the persistent outflows only start to appear after the
leading polarity starts to coalesce. |
| Dr | David Williams | UCL/MSSL | Hinode/EIS observations of ion kappa distributions in active regions of the solar corona. D.Williams, Ed Lee (KU Leuven), Giovanni Lapenta (KU Leuven). | Solar spectroscopy traditionally assumes electrons and ions in coronal plasma exist in Maxwell?Boltzmann distributions, or thermal equilibrium. Many studies in recent decades, however, have investigated the possibility of kappa distributions of coronal and solar wind particles far from Maxwellian and their resulting effects on collision, excitation, and ionization rates, heat transfer, waves, and instabilities. Kappa distributions belong to a class of statistical equilibrium ensembles that are known solutions to the Boltzmann equation, in both collisional (Fokker-Planck) and collisionless (Vlasov) frameworks. They have been observed in situ in the solar wind and in planetary magnetospheres throughout the heliosphere. Using EIS data, we investigate the possibility of suprathermal distributions of coronal ions by fitting the equivalent kappa functions to their emission line profiles. We fit different kappa and Gaussian model functions to line profiles of the strong Fe XV line at 284.16 A, across two large-field rasters taken in an active region. Both single- and double-component Gaussian models are applied, as well as two kappa models, one with a free width parameter allowing for and the other with a constrained width that precludes 'microturbulence'. We then compare the goodness of fit of the computed best fits for each model. The kappa distribution is a generalization, or superset, of the Maxwellian, so they are able to fit line profiles more precisely than a Gaussian. In most of the data, the best-fit kappa model produces much lower residuals across the profile than any single Gaussian and sometimes double Gaussian. Most importantly, the distribution of estimated kappa values is found to lie mostly in the low-k range, implying ion populations far from Maxwellian. We find the shape of the Fe xv line, in the vast majority of the data analyzed, to be indicative of a highly suprathermal ion population. |
| Dr | Davina Innes | Max-Planck-Institut fuer Sonnensystemforschung | Transition region explosive events at the base of mini-CMEs in the quiet Sun | Explosive events are
characterized by
broad non-Gaussian
wings in their line
profiles and are
thought to be the
result of magnetic
reconnection in the
transition region.
SDO/AIA is now
providing images of
these events. By
combining SDO/AIA
images with SUMER
spectra, the
association of
explosive events
with He II
brightenings,
coronal jets, and
sudden dimmings is
investigated. We
find several cases
of explosive events
seen in the O VI
1032 A line that
coincide with
jet-like
brightenings at the
base of EUV coronal
dimmings
(mini-CMEs). Here we
show some examples
and estimate the
energy released in
the events. |
| Dr | Deb Baker | UCL/MSSL | Magnetic Topology, Coronal Outflows and the Solar Wind | van Driel-Gesztelyi, L., Culhane, J.C., Demoulin, P., Mandrini, C.H., DeRosa, M.L.,
Rouillard, A.P., Opitz, A., Stenborg, G., Vourlidas, A., Brooks, D.H.
During 2-18 January 2008 a pair of low-latitude opposite polarity coronal holes
were observed on the Sun flanked by two ARs with the heliospheric plasma sheet
between them. Hinode/EUV Imaging Telescope (EIS) is used to locate AR-related
outflows and measure their velocities. The Advanced Composition Explorer (ACE)
in-situ observations are employed to assess the resulting impacts on the
interplanetary solar wind (SW). Magnetic field extrapolations of the two ARs confirm
that AR plasma outflows observed with EIS are co-spatial with quasi-separatrix
layer locations, including the separatrix of a null point. Global potential field
source-surface modeling indicates that field lines in the vicinity of the null point
extend up to the source-surface, enabling a part of the EIS plasma upflows access
to the SW. Similar upflow magnitude is also observed within closed field regions.
Though part of the plasma upflows observed with EIS remain confined along closed
coronal loops, a subset of them are indeed able to make their imprint in the slow
SW, making ARs bordering coronal holes a slow SW contributor. |
| Mr | Ehsan Pedram | MSSL | CME-RELATED CHANGES IN LINE-OF-SIGHT MAGNETIC FIELD STRENGTH IN DIMMING REGIONS OBSERVED BY HINODE ON 14 DECEMBER 2006 | Following many coronal mass ejections (CMEs), dark areas referred to as coronal dimming regions have been observed to form within and around the erupting active region. We probe the nature of coronal dimmings in relation to the expanding CME through the analysis of the associated photospheric magnetic field in the flare and CME event of 14 December 2006, using data from Hinode?s SOT. We have systematically analysed the variation of the line-of-sight magnetic field strength in a large region surrounding AR 10930 using Hinode SOT Stokes V data. Our analysis, for the first time, shows that at the site of the dimmings there is a decrease in the magnetic field strength at the onset of the dimming in the dominant polarity of the plage regions surrounding the Active Region (AR), persisting during the dimming and recovering at the onset of the intensity recovery reported in Attrill et al. (2010). Using simple geometric arguments we show that the decrease in the dominant polarity flux is consistent with an 35 degrees change in the inclination angle of the photospheric magnetic fields in the plage regions, from horizontal to vertical. We further observe a close correlation between the site of plasma outflow with velocities of 30 km/s and one of the plage regions showing change in magnetic field strength. Our findings indicate a reconguration and opening of the magnetic field lines resulting in a change in their inclination angle in the dominant polarity of the plage regions surrounding the erupting active region. This then leads to a decrease in the plasma density observed as coronal dimming. |
| Dr | Elena Dzifcakova | Astronomical Institute of the Academy of Sciences of the Czech Republic | Kappa-distributions: line intensities and diagnostics for Fe XI and Fe XVII | E. Dzifcakova, G.
Del Zanna, H. Mason
We searched for the
EUV lines of Fe XI
and Fe XVII in the
spectral range
corresponding to the
EIS detectors, which
allow us to diagnose
the
kappa-distributions.
The presence of the
kappa-distribution
in solar corona can
be connected e.g.
with heating
mechanisms by the
magnetic
reconnection. The
synthetic spectra
for different values
of kappa, electron
density, and
temperature were
calculated for new
sets of atomic data.
The type of electron
distribution
together with
temperature and
electron density
affects intensity of
each line. Usually,
the electron density
must be diagnosed
first and then, for
known density,
selected line ratios
give a possibility
to diagnose kappa
and temperature
simultaneously. This
is the case of Fe XI
lines. On the other
hand, the ratios of
Fe XVII lines in the
EIS spectral ranges
are not affected by
electron density.
Therefore Fe XVII
lines give the best
opportunity for
non-Maxwellian
diagnostics. The
line ratios with the
best sensitivity to
the shape of the
distribution
function have been
selected and
diagnostics of the
parameter kappa has
been proposed. The
possibility to
diagnose the
kappa-distributions
from EIS
observations is
discussed. |
| Ms | Elizabeth Doschek | none | | |
| Dr | George Doschek | Naval Research Laboratory | "To Be Or Not To Be" ? Be with Plan B of Solar-C! | George A. Doschek, Space Science Division, Naval Research Laboratory and The Solar-C Teams. What's the future for "Spectroscopy of the Dynamic Sun"? What can we do to try to finally understand the elusive mystery of the solar atmosphere ? how is it formed, what is its detailed structure, how does it evolve, what are the fundamental physical processes involved in the interaction of the Sun's magnetic fields with hot plasma, how is energy transported, stored, and dissipated in the Sun?s atmosphere, how will we understand energy release in flares and coronal mass ejections, and coronal heating in general? I believe that imaging spectroscopy with high time resolution is the key technique for finding answers to these questions. The Japanese Hinode mission with US and UK participation has laid the groundwork for future missions. In the near future the Interface Region Imaging Spectrograph (IRIS) NASA Small Explorer Mission will start the ball rolling in obtaining high time resolution imaging spectroscopy of the chromosphere and also give us a peek into the transition region and corona. The Japanese Solar-C mission is designed to obtain imaging spectroscopy at high spatial and spectral resolution throughout the entire atmosphere, from the photosphere to multimillion degree solar flare plasmas. For the first time, a mission is being developed to study the solar atmosphere as a coupled system from the photosphere into the corona with matched instrumentation. It will require international participation to realize this fantastic state-of-the-art mission. Only with a coupled systems approach can we finally understand the fundamental physics of the solar atmosphere, and presumably the atmospheres of many other stars as well. In this talk, I will discuss the on-going planning and the essential elements of the Solar-C mission as they are currently conceived. |
| Dr | Giannina Poletto | INAF - Arcetri Astrophysical Observatory - Firenze (Italy) | | |
| Dr | Giulio Del Zanna | University of Cambridge | XUV spectroscopy of the solar corona and the relevant atomic data | I will briefly
mention some of the
important
measurements of the
coronal plasma
characteristics that
have been possible
in recent years
thanks to
high-resolution
spectroscopy from
instruments such as
SOHO/SUMER and
Hinode/EIS. I will
then provide an
update on recent
results I have
obtained on atomic
data calculations
and benchmarking of
the coronal iron
ions, with emphasis
on the EUV and Soft
X-rays.
The new atomic data
are important for
EIS and for the SDO
instruments. |
| Dr | Harry Warren | NRL | Spectroscopic Observations of Solar Flares | Peter Young (GMU)
During the past
several years new
spectroscopic
observations of
solar flares have
become available
from EIS/Hinode and
EVE/SDO. EVE
observes every
ionization stage of
Fe from Fe IX to Fe
XXIV and allows for
the thermal
structure of solar
flares to be
examined in detail.
These measurements
show that the
temperature
distribution is
broad, even during
the rise phase of
the flare. This
suggests heating
over many different
independent threads.
In contrast with
EVE, EIS
measurements are
spatially resolved.
Our initial survey
of EIS observations
suggests that these
observations show
much larger velocity
signatures than
spatially averaged
measurements, but
are still
unresolved. We will
present comparisons
with multi-thread
hydrodynamic models. |
| Dr | Helen E. Mason | University of Cambridge | Coronal Iron Ions | H.E.Mason, G.Del Zanna, B.O Dwyer, P.J.Storey,
N.R.Badnell
Coronal iron ions give rise to spectral lines in the
visible, infra-red, ultra-violet and X-rays. They
have been studied for decades, from eclipse
observations to space missions (Skylab, SMM, SoHO,
Hinode). The first comprehensive calculations were
carried out in the 1970 s using the atomic physics
codes developed at UCL. Diagnostic techniques have
been developed and tested against observations for a
whole range of ions. The calculations and line
identifications are still being refined, with recent
work as part of the UK APAP project. This talk will
look back on a lifetime s work to see what progress
has been made. |
| Dr | Hirohisa Hara | National Astronomical Observatory of Japan | Spectroscopy of the site of magnetic reconnection | We report fundamental structures near the site of magnetic reconnection in a type of
solar flares that were observed by the Hinode EUV Imaging Spectrometer. They
consist of a bright source at the top of flare loops, a fast outflow above the bright
source, and an inflow structure. We have estimated the reconnection rate to be
0.01-0.1 from the Doppler velocity measurement by emission-line spectroscopy.
The presence of slow-mode and fast-mode MHD shocks is discussed with
supporting evidence based on the observed quantities. |
| Mr | Hugh Hudson | UC Berkeley and Glasgow | EVE Spectroscopy of Solar Flares | Hugh S. Hudson
The EVE instrument on SDO has brought systematic EUV spectrometry to solar flare
physics, albeit without imaging, at a spectral resolution of about 0.1 nm. I describe
some initial results on Doppler shifts, continua, and charge-exchange signatures of
high-energy particles, and discuss their implications for our understanding of flares. |
| Prof | J. Leonard Culhane | MSSL and ISSI | | |
| Dr | Jaroslav Dudík | Faculty of Mathematics, Physics and Informatics, Comenius University, Bratislava, Slovakia | Diagnostics of the non-Maxwellian kappa-distributions from Hinode/EIS observations | Dudik, J. (1,2), Mackovjak, S. (1,2), Dzifcakova, E. (2) (1) - Dept. of Astronomy, Physics of the Earth and Meteorology, Faculty of Mathematics, Physics and Informatics, Comenius University, Bratislava, Slovakia (2) - Astronomical Institute of the Academy of Sciences of the Czech Republic, Ondrejov, Czech Republic We investigate line ratios suitable for diagnostics of temperature, density, and the type of the electron distribution in the coronal and transition region spectra observed by Hinode/EIS. Density diagnostics using lines of elements other than Fe are sought. Such line ratios should not be dependent on kappa. The quality of such density diagnostics is assessed and it is found that all of the investigated density-sensitive ratios suffer from largely unknown blends. Therefore, we diagnose the density using Fe line ratios. Subsequently, we search for methods suitable for simultaneous diagnostics of kappa and temperature. We show that such diagnostics is indeed possible, but suffers from large errors due to photon noise. However, the observed O IV and O V line ratios provide indications of strong departures from the Maxwellian distribution. We discuss the implications of non-Maxwellian distributions for the coronal heating. |
| Dr | Jaroslav Dudík | Faculty of Mathematics, Physics and Informatics, Comenius University, Bratislava, Slovakia | The optically thin continuum for the non-Maxwellian distributions (Poster) | Dudik, J., Kasparova, J., Dzifcakova, E., Karlicky, M., Mackovjak, S. We calculate the optically thin EUV, X-ray and radio continua arising due to free-free and free-bound transitions in the coronal and flare plasmas characterized by non-Maxwellian kappa- and n-distributions. The continua are highly dependent on the assumed type of distribution. The free-free continuum is sensitive to the type of distribution mainly in the X-ray range, but is not sensitive to the type of the distribution for radio wavelengths. The height of the ionization edges in the free-bound continua are also affected by the type of the distribution. The ionization edges disappear for n-distributions due to the decreased number of low-energy electrons, forming a smooth continuum for n > 5. For the kappa-distributions, the ionization edges are greatly increased and in principle allow for determination of kappa using the observations of the continuum. Since the height of the ionization edges depends on the number of low-energy electrons, such diagnostics allows for sampling the low-energy end of the distribution function. |
| Dr | Jay Bookbinder | Smithsonian Astrophysical Observatory | | |
| Prof | Joan Schmelz | University of Memphis | Spectroscopy of Coronal Loops | J. T. Schmelz,
University of Memphis
Without spectroscopy, what would we know about
coronal loops? Would we, could we know the
temperature, density, or composition of their photon-
emitting plasma? Could we know their magnetic field
strength and structure? Would we even know of their
existence? Spectroscopy has been the key to the
discovery of the million-degree corona and the
dominance of the magnetic loop population. Coronal
loops may yet provide the elusive answer to the
coronal heating problem, and it will be spectroscopy
that provides the fundamental foundation for the
discovery. In this talk, I will discuss both the
historical and continuing contributions of
spectroscopy to coronal loop science, from Skylab?s
Spectrograph and Spectroheliograph to Hinode?s EUV
Imaging Spectrometer, as well as the imagers that
have been based on spectroscopic science. Although we
still argue about the cross-field temperature
distributions, the accuracy of density-sensitive line
ratios, and the elemental abundances of coronal loop
plasma, it is spectroscopy itself that allows us not
only to have these arguments but also to make
progress on essential coronal science.
|
| Dr | Kelly Korreck | Smithsonian Astrophysical Observatory | Pre-Flare temperature diagnostics in the EUV | K.E. Korreck - SAO,
A. Sturner-Haverford
College
EUV observations of
flaring active
regions in solar
corona indicated a
possible temperature
precursor to flaring
activity. SDO?s AIA
instrument with its
continuous full disk
coverage allows for
a more systematic
exploration of this
effect. The
resolution both
temporal and spatial
will aid in
addressing the
presence and amount
of pre-heating.
This poster examines
active regions using
the SDO/AIA EUV
telescopes prior to
flaring events to
characterize their
emission in the 7
EUV bandpasses
available. The link
between the
pre‐flare
brightening and
energetic particle
events will also be
examined. This work
could prove
invaluable to the
prediction of space
weather events such
as flares. |
| Prof | Kenneth J.H. Phillips | Mullard Space Science Laboratory, University College London | Solar Flare Element Abundances from RESIK and other spectrometers | K. J. H. Phillips, J. Sylwester, B. Sylwester, G. A.
Doschek, J. L. Culhane, V. D. Kuznetsov.
The RESIK crystal spectrometer on board CORONAS-F
operated during maximum solar activity in 2002/2003,
and many thousands of spectra acquired during flares
as well as non-flaring times from bright active
regions. George Doschek was centrally involved in the
making of the instrument, providing the excellent
silicon and quartz crystals with his NRL team. A
detailed characterization of the various instrument
parameters has led to a calibration of the spectra
with unprecedented precision and the solar continuum
to be unambiguously observed for two of RESIK s four
channels. All this has enabled element abundances to
be obtained from the fluxes of the large variety of
spectral lines in the 3-6 Angstrom range. A
comprehensive programme over the past 2 years has
resulted in the determination of Ar and S abundances
as well as those of K and Cl. A wide range of first
ionization potentials are represented, so the nature
of the FIP effect can be examined in a new light:
thus for the low-FIP K, the abundance in flares is
nearly a factor 6 more than photospheric or
meteoritic, but Ar and S flare abundances are very
similar to their photospheric abundances. For non-
flaring active regions K is much more abundant. There
is broad agreement of our derived abundances with the
recent theory of Laming. The presence of the He-like
K lines in RESIK spectra has led to the
identification of the same lines in the spectra of RS
CVn binary stars. Our method of abundance analysis
has inspired us to look again at the S line spectra
from the Yohkoh BCS that were studied by Tetsuya
Watanabe in the 1990s. The success of the RESIK
results has resulted in a proposed new crystal
spectrometer, ChemiX, to be flown on the Russian
Interhelioprobe spacecraft, tentatively due for
launch in 2018.
|
| Dr | KHELFI | Researcher | Propagation of p-modes in a magnetic structure with flow | The solar sub-photospheric zone is a huge reservoir of a mechanical
energy generated by the convective motion which takes place in the convective
zone. The perturbations induced by this motion generate a wide spectrum of
acoustic waves (P modes) which have been observed at a photospheric level.
Recent space based observations suggest that these P modes can manifest them-
selves as slow magneto-acoustic waves while propagating in coronal magnetic
structures such as coronal loops which are anchored in the solar photosphere
into sunspot regions. Consequently, in order to show theoretically the possible
occurrence of this scenario, we present in this work a detailed analysis of the
interaction of a P mode with a sunspot under typical photospheric conditions.
For this we consider a simple slab configuration made of a non-magnetized and
a magnetized (sunspot) region with presence of a flow at the interface. The
conditions under which an acoustic wave is transmitted into the magnetized
region as a magneto-acoustic wave are studied in details. The transmission and
reflection angles and the transmittance and reflectance of the magneto-acoustic
wave are calculated and examined. They reveal that the transmitted wave is a
slow magnetoacoustic wave which propagates upwards guided by the magnetic
field which confirms the recent observations. |
| Dr | Leon Golub | Harvard-Smithsonian CfA | | |
| Dr | Luca Teriaca | Max Planck Institute for Solar System Research | Quiet Sun electron densities from the C III 97.7/117.6 line ratio | L. Teriaca, V. Andretta
In a fully ionized plasma, the measurement of the
electron density provides a direct measurement of the
mass density, a fundamental thermodynamic variable in
all studies of the solar atmosphere.
The most reliable method to measure the electron
density involves the ratio of spectral lines, or
groups of lines, from the same ion but with
substantially different spontaneous decay
coefficients Normally such ratios involve very weak
forbidden lines posing serious problems to the study
of even slowly evolving phenomena. One of the most
remarkable exception is the ratio of the C III 97.7
nm line with the C III multiplet at 117.6 nm, being
both very bright features of the solar VUV spectrum.
However, the 117.6 nm multiplet is potentially
blended with a autoionization lines from S I. Here we
evaluate the importance of such blend in different
solar regions and in solar-like stars and discuss the
usability of the 97.7/117.6 ratio under quiet Sun
conditions. |
| Dr | Mark Weber | CfA / SAO | Morphology and Temperature of a Hot Prominence Cavity Observed with Hinode and SDO | Mark Weber (SAO), Katherine K. Reeves (SAO), Sarah E. Gibson (HAO/NCAR), and
Therese A. Kucera (NASA/GSFC)
Prominence cavities appear as circularly shaped voids in coronal emission over
polarity inversion lines where a prominence channel is straddling the solar limb.
The presence of chromospheric material suspended at coronal altitudes is a
common but not necessary feature within these cavities. These voids are observed
to change shape as a prominence feature rotates around the limb. We use a
morphological model projected in cross-sections to fit the cavity emission in
Hinode observations, and then apply temperature diagnostics to Hinode and SDO
data to investigate the thermal structure. We find significant evidence that the
prominence cavity is hotter than the corona immediately outside the cavity
boundary. This investigation follows upon "Thermal Properties of A Solar Coronal
Cavity Observed with the X-ray Telescope on Hinode" by Reeves et al., 2012, ApJ,
in press. M. Weber and K.K. Reeves are supported under contract NNM07AB07C
from NASA to SAO. T. Kucera is supported by an award from the NASA SHP
Program. |
| Dr | Matthew West | Royal Observatory Belgium | Coronal Seismology Using EIT Waves: Estimation Of The Coronal Magnetic Field Strength In The Quiet Sun | M. J. West, A. N.
Zhukov, L. Dolla, L.
Rodriguez
Coronal EIT waves
have been observed
for many years. The
nature of EIT waves
is still
contentious, however
there is strong
evidence that some
of them might be
fast magnetosonic
waves, or at least
have a fast
magnetosonic wave
component. The wave
speed is formed from
two components; the
Alfven speed
(magnetic) and the
sound speed
(thermal). By making
measurements of the
wave speed, coronal
density and
temperature it is
possible to
calculate the quiet
Sun coronal magnetic
field strength
through coronal
seismology. In this
work we investigate
an EIT wave observed
by the SECCHI/EUVI
instruments on-board
the STEREO
satellites. The wave
epicenter was
observed at disk
center in the STEREO
B (Behind)
satellite. At this
time the STEREO
satellites were
separated by
approximately 90
degrees, and as a
consequence the
STEREO A (Ahead)
satellite observed
the wave on the
solar limb. These
observations allowed
us to make accurate
speed measurements
of the wave. The
background coronal
density was derived
through Hinode/EIS
observations of the
quiet Sun and the
temperature was
estimated through
the narrow
temperature response
in the EUVI
bandpasses. The
density, temperature
and speed
measurements allowed
us to estimate the
quiet Sun coronal
magnetic field
strength to be
approximately 0.7 ±
0.7 G. |
| Mr | Naomasa Kitagawa | University of Tokyo | The evolution of chromospheric evaporation observed with Hinode/EIS | N. Kitagawa & T. Yokoyama (University of Tokyo, Japan)
Department of Earth and Planetary Science, University of Tokyo, Hongo 7-3-1,
Bunkyo, Tokyo, 113-0033 Japan
The evolution of chromospheric evaporation observed with Hinode/EIS
We analyzed the ongoing chromospheric evaporation in the impulsive phase.
The dense and cool plasma in the chromosphere experiences impulsive heating
by nonthermal particles produced at the flare reconnection site. The gas
pressure suddenly rises, which results in so called chromospheric evaporation,
fast upflow with several hundreds km/s. The chromospheric evaporation was
detected as the blueshifted component in Ca XIX line profiles (Antonucci et al.
1982). Czaykowska et al. (1999) firstly reported spatially resolved evaporation
in the gradual phase observed with the Coronal Diagnostic Spectrometer (CDS)
onboard the Solar and Heliospheric Observatory (SOHO). Recent observations
by Hinode/EIS revealed more detailed structures. The temperature dependence
of the evaporation velocity was reported by Milligan & Dennis (2009). The fast
upflow from the footpoints of flare loops was found during the early phase
(Watanabe et al. 2010; Del Zanna et al. 2011). Chen & Ding (2010) found a
temporal correlation between the blueshift and line width.
In this study, the enhanced blue wings (~400km/s) were found in Fe XXIII and
XXIV profiles in the growing flare loops. Other coronal lines at the evaporation
site also show the velocities near the sound speed in each formation
temperature. The upflow is switched into downflow at several MK. Fortunately,
in the data used here the EIS spectroscopic slit cut across old and new flare
loops simultaneously, which enables us to discuss the temporal evolution.
|
| Dr | Naoto Nishizuka | ISAS/JAXA | Time variation of Active region outflow with recurrent flows and waves | Naoto Nishizuka
(ISAS/JAXA) and
Hirohisa Hara
(NAOJ):
Raster scan
observations with
EIS/Hinode have
revealed
characteristics of
steady outflow from
the edge of active
regions.
Furthermore, recent
observations of EIS
with sit-and-stare
mode have also
revealed unsteady
features of the AR
outflow. Here we
report the
sit-and-stare
observation data of
NOAA 10942 on 2007
February 20 and
analyzed the data
above the base of
the outflow and
found both
continuous outflows
and waves, which
propagate from the
base of the outflow.
The spectra at the
base of the outflow
and at higher
locations show
different
properties. The line
profiles show
blue-side asymmetry
at the base of the
outflow where
nonthermal
broadening becomes
large because of
fast upflows
generated by heating
events. On the other
hand, at higher
locations line
profiles are
symmetric and the
intensity
disturbances vary in
phase with the
velocity
disturbances,
indicating upward
propagating
slow-mode waves.
High cadence
spectroscopic
observations
revealed
intermittent
signatures of
nonthermal
velocities with 2
minutes period and
2?? size. Each of
them seems to
correspond to the
base of the
propagating
disturbances. The
similarity of line
profiles of the
outflow and the jet
may indicate that
the flows and waves
originate in
unresolved explosive
events in the lower
atmosphere of the
corona.
|
| Ms | Neda Dadashi | Max Planck Institute for Solar System Research | Doppler shift of hot coronal lines in a Moss Area of an Active region | N. Dadashi, L.
Teriaca, D.
Tripathi, S. K.
Solanki
We use a novel
technique that
allows determining
the absolute Doppler
shift of EUV lines
by combining
observations from
the SUMER and EIS
spectrometers. This
technique, developed
and successfully
applied to quiet Sun
data, is now used to
investigate the
absolute Doppler
shift of lines
formed at
temperatures between
1 MK and 2.5 MK in a
moss area within
active region NOAA
11243.
The moss is the area
at the footpoint of
the hot (3 to 5 MK)
loops forming the
core of the active
region where
emission is believed
to result from the
heat flux conducted
down to the
transition region
from the hot loops.
Thus, studying the
variation of Doppler
velocity over the
moss area can give
clues on the heating
mechanism in the hot
loops in the core of
the active regions.
Preliminarily
results for the
center of the moss
area shows roughly
constant blue shift
(upward motions) of
-5 km/s in the
temperature range of
1MK to 1.6MK. For
hotter lines the
amount of upward
motions decrease and
reaches to -1 km/s
for Fe XV 284. The
measurements are
discussed with
respect to models of
the heating of such
hot loops.
|
| Mr | OYELEKE OLAOSEBIKAN | THE FEDERAL POLYTECHNIC OFFA, KWARA STATE, LADOKE AKINTOLA UNIVERSITY OF TECHNOLOGY, OGBOMOSO | Comparative study of the output of Amorphous Silicon Photovoltaic Solar Cells when receiving Direct and Diffused Radiations | Author: Oyeleke, O
(1)
Co-Author: Fajinmi,
G.F (2)
Four Amorphous
Silicon Photovoltaic
cells rated 12V,
20amps, 30watt DC
were subjected to
solar radiations
study with the aim
to determining their
output at different
positions. The four
amorphous Silicon
Photovoltaic were
paired in two. A
pair was placed on a
sun tracker while
the other was placed
on a fixed position.
An LDR cell was
constructed to
control the tracking
system while an LED
was connected ton
indicate the
radiation intensity
at a particular
time. The output
power for both
arrangements were
recorded at
10minutes interval
for a period of two
months. The data
obtained were
compared and treated
to obtain a model of
mean output power at
a particular
temperature for the
two pairs
separately. It was
observed that the
mean output power of
the setup on
tracking mechanism
has a higher mean
output power. |
| Dr | P. F. Chen | UCL/MSSL & Nanjing University | The puzzling red shift behind the coronal EIT wave | P. F. Chen and L. K.
Harra
Generally
blue-shifted
outflows are
associated with
dimmings which
expand behind EIT
waves, which can be
understood since
magnetic field lines
are stretched up
during the eruption,
taking along with
the coronal plasma.
With the
high-cadence
sit-and-stare mode
of the Hinode/EIS
observations, Harra
et al. (2011) found
two waves in the
coronal lines, with
the faster one being
a coronal Moreton
wave, and the slower
one probably being
an EIT wave.
Following the slower
wave, Hinode/EIS did
show blue shifts.
However, the blue
shifts soon turned
to be red shift,
which is a little
puzzling. With MHD
numerical
simulations of
coronal mass
ejections (CMEs), we
try to understand
how the red shifts
are formed below the
CME eruption. |
| Dr | Paola Testa | Harvard-Smithsonian Center for Astrophysics | Combined AIA/EIS diagnostics for high temperature plasma in active regions | We use coronal imaging observations with SDO/AIA, and Hinode/EIS spectral
data, to explore the potential of narrow band EUV imaging data for diagnosing
the presence of hot (T > 5MK) coronal plasma in active regions.
We analyze observations of two active regions with simultaneous AIA imaging,
and EIS spectral data, including the CaXVII line which is sensitive to hot coronal
plasma even outside flares.
After careful co-alignment of the imaging and spectral data, we compare the
morphology in a 3 color image combining the 171, 335, and 94A AIA spectral
bands, with the image obtained for CaXVII emission from the analysis of EIS
spectra. We find that in the selected active regions the CaXVII emission is strong
only in very limited areas, showing striking similarities with the features
bright in the 94A AIA channels and weak in the 171A band.
We conclude that AIA imaging observations of the solar corona can be used to
track hot plasma, and thus to study its spatial variability and temporal evolution
at high spatial and temporal resolution.
|
| Mr | Patrick Serengulian | none | | |
| Dr | Pavel Kotrc | Astronomical Institute, Academy of Sciences, Ondrejov, Czech Republic | Spectroscopic study of solar filaments/prominences ? ground based observations. | Kotrc P.(1), Schwartz P.(1) and Kupryakov Yu. A.(2)
(1)Astronomical Institute, Ondřejov, Czech Republic,
(2) GAISH, MGU, Moscow, Russia
We present an overview of tools and methods we use
for a multispectral study of solar filaments and
their EUV channels. Particularly, we concentrate on
using and description of the ground based part of the
project ? the spectroscopic observations of filament
and prominences. Spectra nad filtergrams of a large
set of quiescent prominences/filaments observed at
the Ondrejov laboratory spectrograph are used for
determinantion of optical thickness and integral
intensity in the H-alpha line. The main aim is to
contribute to multiwavelength analysis and
computations of the prominence/filament mass loading.
We want to study distribution and limits of the
prominence mass interval in more details. |
| Dr | Pavol Schwartz | Astronomical Institute, Academy of Sciences of the Czech Republic | Prominence mass estimated from multi-spectral data | P. Schwartz, P. Heinzel, P. Kotrc, U. Anzer and Yu. A. Kupryakov
A spectroscopic method for estimation of the total mass of a prominence
from multi-spectral observations was developed. Observations in EUV by
AIA instrument on board of SDO, in soft X-rays by XRT on Hinode
and in H_alpha by MFS spectrograph of the Ondrejov observatory are
used. The total mass of a prominence is obtained by integration over the whole
prominence area, of the column mass derived from column densities which are
obtained using a semi-automatic code developed according to the method of
Heinzel et al. (2008). Non-symmetrical distributions of the coronal X-ray and EUV
emissivities in front of and behind the prominence is taken into account as well.
We use the so-called alpha factor defining a fraction of the emissivity behind the
prominence. The mass determination then depends on the correct specification of
this factor. Alpha factor is estimated iteratively by comparing a ratio of the optical
thicknesses at 193 A and 211 A derived from observations with the theoretical
value calculated according to Anzer & Heinzel (2005). The robustness of the
method is tested on several prominences and derived alpha values are compared
with approximate value obtained from the intensities measured on
the disk and at the limb close to a prominence. |
| Dr | Peter Young | George Mason University | Advances in solar spectroscopy from Hinode/EIS | Tetsuya Watanabe and
George Doschek were
instrumental in
developing and
leading the
Hinode/EIS project,
which has led to
great advances in
the application of
spectroscopic
techniques for
studying the solar
corona. EIS directly
benefited from
Tetsuya and George s
experience in solar
spectroscopy as the
wavelength bands
they helped select
gave access to some
of the best plasma
diagnostics at
coronal
temperatures. This
presentation will
focus on new science
that has become
possible with EIS,
with particular
attention to density
diagnostics and
velocity
measurements in
active regions.
|
| Prof | Petr Heinzel | Astronomical Institute, Academy of Sciences, Czech Republic | SDO/EVE spectra of solar flares: Non-LTE models of EUV continua | P. Heinzel, E.H. Avrett, E. Dzifcakova, A. Berlicki
For selected flare events we present the SDO/EVE spectra of hydrogen and helium EUV
resonance continua and compare them with the results of the non-LTE transfer
computations based on various flare models. We discuss the formation of these
continua and their diagnostic potential for determination of the temperature structure
of the flaring atmosphere. Non-thermal processes are also considered. This work
represents the basis for future analysis of the EVE flare spectra and has also a direct
relevance to stellar flare spectroscopy.
|
| Dr | Randall Smith | Smithsonian Astrophysical Observatory | Solar and Stellar Spectroscopy with X-ray Microcalorimeters | Jay Bookbinder (SAO), Simon Bandler and the NASA/GSFC calorimeter team
We present the science case for a broadband X-ray imager with high-resolution
spectroscopy for both stellar and solar observations. In the solar case, high-
resolution X-ray spectral images of both active regions and solar flares can be
measured, while a stellar spectrometer would be able to survey hundreds of
nearby solar-type stars. This relies upon major advances recently made in
transition-edge sensor (TES) detector technology that enable resolution better
than 2 eV in an array that can achieve high count rates. Combined with an X-ray
mirror, this instrument would combine arcsecond-scale imaging with high-
resolution spectra over a modest field of view, enabling a wide range of studies
such as the detection of microheating in active regions, ion-resolved velocity
flows, and the presence of non-thermal electrons in hot plasmas. |
| Dr | Richard Morton | University of Sheffield | Chromospheric jets at the edges of sunspots | Recent results have demonstrated that the chromosphere may play an important role
in determining the energetics and dynamics of the corona. While the properties of
chromospheric jets are well documented at the limb, in coronal holes and plage
regions, details of the jets in and at the boundaries of sunspots are scarce. Using
Hinode and TRACE we analyse the properties of jets located at the boundary of a
sunspot as it crosses the limb. The jets are seen to continuously raise
chromospheric plasma to coronal heights and demonstrate collective behaviour.
Enhanced emission at the leading edge of jets suggests the formation of shock
fronts leading to heating of the chromospheric plasma. This is supported by
emission above the limb observed in the TRACE 1550A and 1600A bandpasses. |
| Dr | Ryan Milligan | Queen s University Belfast | Spatially-resolved nonthermal line broadening during the impulsive phase of a solar flare | In this work, which utilises data from the EUV Imaging Spectrometer (EIS) onboard
Hinode, broadened line profiles were observed to be co-spatial with two HXR
footpoints as observed by RHESSI during the impulsive phase of a C-class flare. By
plotting the derived nonthermal velocity for each pixel within the Fe XV and Fe XVI
rasters against its corresponding Doppler velocity a strong correlation was found
between the two parameters for one of the footpoints. This suggested that the
excess broadening at these temperatures is due to a superposition of flows
(turbulence), presumably as a result of chromospheric evaporation due to
nonthermal electrons. Also presented are diagnostics of electron densities using five
pairs of density-sensitive line ratios. Density maps derived using the Mg VII and Si X
line pairs showed no appreciable increase in electron density at the footpoints, while
the Fe XII, Fe XIII, and Fe XIV line pairs revealed densities approaching 10^11.5 cm
−3. Using this information, the nonthermal velocities derived from the widths of the
two Fe XIV lines were plotted against their corresponding density values derived
from their ratio. This showed that pixels with large nonthermal velocities were
associated with pixels of moderately higher densities. This suggests that nonthermal
broadening at these temperatures may have been due to enhanced densities at the
footpoints, although estimates of the amount of opacity broadening and pressure
broadening appeared to be negligible. |
| Dr | Sarah Matthews | UCL-MSSL | Chromospheric evaporation, WLFs and SQs | Sarah Matthews, Sergei Zharkov, Nariaki Nitta
Whether WL emission is really common to all flares is likely to be elucidated with the
continuous observations now available from SDO, but it remains the case that some
M- and X-class flares show surprisingly little emission in the WL, the reasons for
which are still unknown. A recent study (Pedram and Matthews (2012)) of the HXR
and WL characteristics of WLFs with and without associated sun-quakes found some
evidence for steeper HXR spectra and higher WL contrast in flares with no associated
quakes, while Matthews et al (2003) in their survey of Yohkoh WL and non-WL flares
found a strong correlation between the incidence of WL emission and high coronal
pressure, as well as with the hardness of the HXR spectrum derived from the M2/M1
ratio on HXT. In an attempt to tie these various different observations together we
present preliminary results for a flare observed by Hinode, RHESSI, STEREO and SDO
in February 2011 in order to study correlations between lower energy electrons,
associated chromospheric evaporation, WL contrast and SQs. |
| Dr | Sergei Zharkov | MSSL/UCL | | |
| Dr | Sergey Shestov | Lebedev Physical Institute | EUV spectra of intense solar flares obtained by SPIRIT spectroheliograph | S. Kuzin
We present EUV spectra of several intense solar
flares, registered by spectroheliograph SPIRIT aboard
Russian CORONAS-F satellite (2001-2005). SPIRIT
consisted from two channels ? for the 176-207 and 280-
330 A spectral ranges, each channels was built on a
slitless optical scheme with grazing incidence
diffraction grating. Field of view of the instrument
covered the whole solar disk which allowed us to
register several dozens of flares during the satellite
lifetime. Identification of spectra, registered by
SPIRIT, is complicated by blending of most of the
spectral lines, since the instrument had moderate
spectral resolution of 0.1 A. We have developed a
method for spectra identification to take the blending
into account. For each spectrum we apply the
following: firstly measure the most intense lines,
than in iterative way calculate DEM, calculate
synthetic spectrum (using CHAINTI) and fit the
experimental spectrum using synthetic one as initial
fit. Using synthetic spectrum as initial fit allows
one to assess degree of blending and measure
intensity of a particular line with a better accuracy.
After several iterations (we apply 5 steps which is
quite enough) most of the lines in experimental
spectrum can be fitted with DEM/synthetic spectrum
with accuracy of a factor of 2.
In the talk we will discuss features of SPIRIT
spectral observation, method details and main results
of spectra identification.
|
| Mr | Stefano Pucci | Universita` di Firenze | Key Differences between Standard and Blowout Jets in Polar Coronal Holes | Pucci, S., Poletto,
G., Sterling, A.C.,
Moore, R.L.,Romoli,
M. and Bemporad,
A.Moore et al.
(2010) suggested
that polar coronal
holes host two kind
of jets: standard
and blowout. In
standard jets an
X-ray flaring arcade
within the jet base
appears offset to
one side of the
Bright Point arcade;
in blowout jets cool
material erupts from
the flare arcade,
making blowout jets
and coronal mass
ejections share a
similar
configuration.
Examples of jets of
the two types have
been presented, but
an analysis of the
physical parameters
of these two jet
categories has not
been done. In this
work we examine
HINODE/XRT and
STEREO/SECCHI
observations of a
standard jet that
occurred in the
northern polar
coronal hole on July
1, 2008, and of a
blowout jet that
occurred in the
southern polar
coronalhole on
November 3, 2007,
with the aim of
identifying the
physical parameters
of the two events.
To this end, we
analyzed XRT
Al-poly, C-poly,
Al-mesh filters
mages of the
standard jet,
Al-poly images of
the blowout event
and EUVI images of
both jets. After
illustrating the
morphology of the
events, we present
the results of a
filter ratio
technique applied to
XRT and/or EUVI
data, depending on
data availability.
Temperature profiles
along the jet as
well as a function
of time have been
inferred. The
standard jet turns
out to be cooler
than the blowout jet
and hardly
identifiable in EUVI
images while the
blowout jet shows up
clearly both in XRT
and in EUVI 195 and
284 channels. High
cadence temperatures
have been derived
only for the
standard jet when
multiple XRT filters
data are available
and do not show an
obvious trend over
the entire duration
of the event.
Densities, inferred
from Emission
Measures, rapidly
decrease with
distance along the
standard jet.
An analysis of
STEREO/COR1 and
SOHO/LASCO C2 images
concludes our work. |
| Dr | Susanna Parenti | Royal Observatory of Belgium | Prominences observations with SDO/AIA | S. Parenti, B.
Schmieder, P.
Heinzel, L. Golub
The
Prominence-Corona-Transition-Region
(PCTR) plays a key
role in the thermal
and pressure
equilibrium of
prominences.
However, several
open issues limit
our knowledge of
this important
interface. Among
them we find the
thermal structure
and the maximum
temperature of its
emitting plasma.
This work is a new
step toward
resolving these
issues. By noting
that prominences may
be observed in
emission in the 171
and 131 SDO/AIA
images, while they
are seen in
absorption in others
(e.g. 193) we
investigate the
temperature content
of these channels.
Using the CHIANTI
atomic database and
previously derived
prominence DEMs, we
built synthetic
spectra in these AIA
channel to establish
the main
contributors. We
find that the Fe IX
line always
dominates the 171
band, even in
absence of a coronal
plasma, while the
131 channel is
dominated by Fe
VIII. Our conclusion
is that the PCTR
reaches, at least,
4x10^5 K. |
| Dr | Takako Kato | National Institute for Fusion Science | Plasma diagnostics using intensity ratios for plasma dynamics | Spectral information is a useful way to know the behavior of plasma especially
when we can
not directly reach the plasma. Spectral line intensity ratios have been used for
plasma diagnostics for temperature and density. In the past we
studied He-like iron spectra from solar flares using observations by the
?Hinotori? and ?Yohkoh? satellites. We found a deviation from ionization
equilibrium in solar flares. This result is related to the plasma dynamics of the
flare.
In this paper, we discuss spectra of He-ike C ions measured in the Large Helical
Device
(LHD) at the National Institute for Fusion Science. The LHD is one of the world?s
largest stellarators for fusion research. We studied the time dependent intensity
ratios of intercombination lines to the resonance line of He-like C ions. We
derived the electron temperatures from the intensity ratios and obtained the
position of He-like C ions in plasma. We study the behavior of ions in plasma
from the time variation of the position of C ions. It is found that the ionizing
state is dominant for He-like C ions even after the energy source is off. These
ions are moving towards the hot plasma center after the energy source turns off.
|
| Prof | Tetsuya Watanabe | National Astronomical Observatory of Japan | FeXVII Emission Line Intensity Ratios Seen in EIS and LHD - still the present continuous tense - | T. Watanabe (NAOJ),
H. Hara (NAOJ), N.
Yamamoto (Osaka U.),
D. Kato (NIFS), H.
A. Sakaue (NIFS), I.
Murakami (NIFS)
Ne-sequence iron
ions, FeXVII, are
formed around the
temperature of log
Te ~ 6.7, which
nearly corresponds
to the maximum
temperature reached
in solar active
regions. The EIS
instrument on board
the Hinode mission
has detected several
week FeXVII emission
lines appearing in
its observing
wavelengths (170 -
210 A, 250 - 290 A),
and they are
identified as those
from the transitions
between 2p^5 3s/3p -
2p^5 3p/3d.
The observed line
intensity ratios
among them are
compared with our
theoretical
calculations. Many
of them are blended
by lower-temperature
weak coronal lines,
and especially the
photon branching
ratio of the 2p^5 3p
^3S_0 level to the
2p^5 3s levels has
been found wrong by
a factor of ~ 2.
The intensity ratio
of the above two
lines have been also
measured in the
Large Helical Device
(LHD) at NIFS
(National Institute
for Fusion Science)
recently, and they
are found more or
less consistent to
the theoretical
prediction in our
preliminary
analysis.
We also try to
measure these line
intensities via a
compact/corona EBIT
(CoBIT)facility
developed at NIFS
and ECU (University
of
Electro-Communications),
but we have not been
successful so far,
although the
resonance lines of
FeXVII appearing in
soft X-ray
wavelengths of 15 -
17 A were observed. |
| Dr | Toshifumi Shimizu | ISAS/JAXA | Development of the coronal plasma in an emerging flux region | T. Shimizu, S. Imada, N. Nishizuka (ISAS/JAXA)
This talk will present the overall behaviors revealed from EIS, XRT, and SOT
observations of an emerging flux region well observed in 29-31 December 2009
and discuss the overall nature of active-region plasma in response to magnetic
field development at the solar surface. Sunspots are newly formed with successive
emergences of magnetic flux from below the surface (See Shimizu, Ichimoto,
Suematsu 2012 ApJ 747 L18 for discovery of an interesting precursory signature
of the sunspot penumbra s formation). Chromospheric plasma ejections as well as
coronal microflares were frequently produced in response to the evolution of
photospheric magnetic fields appeared at the photosphere. We have identified the
formation of a magnetic channel formed in the developing sunspot as one of key
magnetic field structures for producing coronal microflares and chromospheric
ejections frequently. The EIS repeated sparse raster observation provides the
temperature structure as well dynamical behaviors (measured as Doppler velocity
and line width) with spectral lines including OVI, FeX, FeXII, FeXV and FeXXIII and
allows us to discuss observationally how the hot and warm plasma is developed in
the active region with occurrence of microflares. |
| Dr | Uri Feldman | Artep Inc. 2922 Excelsior Spring Court Ellicott City, MD 21042, USA | Coronal heating - why have we not solved the problem and the kind of spectroscopic measurements that may help resolving it | The talk will explore the reasons of why is it that
in spite of six decades of extensive solar physics
research, and the launch into space of ever more
sophisticate instruments there is still no
satisfactory model explaining how solar upper
atmosphere plasmas are being created and sustained.
When attempts were made to derive such models
assumptions were used that although at the time made
a lot of sense subsequently where proven wrong.
Clearly when such occurred the field suffered
setbacks.
In the course of the talk observational procedures
will be suggested that if implemented could establish
reliable facts on which a satisfactory coronal model
could be based.
|
| Prof | Viggo Hansteen | Institute of theoretical astrophysics, University of Oslo | Transition region redshifts and the mass balance of the chromosphere, transition region and corona. | In general and on average observations of transition region emission lines reveal the
presence of redshifts in lines formed from the top of the chromosphere up to
temperatures of about 250000 K and blueshifts for temperatures greater than that.
However, it is doubtful that the apparent large downward flows in the lower
transition region represent a net flow emptying of the corona, so some mechanism
must be responsible for maintaining the mass balance between the lower
atmospheric layers and the corona. We use a 3D-MHD code, Bifrost, which includes
non-grey, non-LTE radiative transfer in the photosphere and lower chromosphere,
optically and effectively thin radiation in the upper chromosphere, transition region
and corona, conduction along the magnetic field lines and
heating through the ohmic dissipation of tangled magnetic field lines to simulate the
solar atmosphere. The motion of material originally in the transition region is
tracked as a minority fluid. We report on the coronal mass balance and the mass
flow mechanism for conditions perhaps typical of the quiet sun.
|
| Dr | Wardella W. Doschek | None | | |
| Dr | Yuan-Kuen Ko | Naval Research Laboratory | A Study in a Decaying Ephemeral Region on the Correlation of Coronal Properties and Solar Magnetic Field | Yuan-Kuen Ko (Naval Research Laboratory), Peter R. Young (George Mason
University), Karin Muglach (Artep, Inc.), Enrico Landi (University of Michigan),
Uri Feldman (Artep, Inc.) and Harry P. Warren (Naval Research Laboratory)
Solar magnetic field is the underlying source that supplies energy to the corona
and governs the coronal plasma properties. This work investigates the
relationships among coronal properties, namely, the electron temperature,
electron density and elemental abundance, and how these coronal properties
depend on the strength of the photospheric magnetic field. The data are from
observations of a decaying ephemeral region by Hinode/EIS during the course of
four days on December 7-11, 2009. We found that there is a positive correlation
between Si/S abundance ratio and the electron density/temperature, and the
average electron density in this region correlates best with the average unsigned
photospheric magnetic field strength.
|
