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Author name code: jejcic
ADS astronomy entries on 2022-09-14
author:"Jejcic, Sonja"
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Title: Coronal mass ejection followed by a prominence eruption and
a plasma blob as observed by Solar Orbiter
Authors: Bemporad, A.; Andretta, V.; Susino, R.; Mancuso, S.; Spadaro,
D.; Mierla, M.; Berghmans, D.; D'Huys, E.; Zhukov, A. N.; Talpeanu,
D. -C.; Colaninno, R.; Hess, P.; Koza, J.; Jejčič, S.; Heinzel,
P.; Antonucci, E.; Da Deppo, V.; Fineschi, S.; Frassati, F.; Jerse,
G.; Landini, F.; Naletto, G.; Nicolini, G.; Pancrazzi, M.; Romoli,
M.; Sasso, C.; Slemer, A.; Stangalini, M.; Teriaca, L.
2022A&A...665A...7B Altcode: 2022arXiv220210294B
Context. On 2021 February 12, two subsequent eruptions occurred above
the western limb of the Sun, as seen along the Sun-Earth line. The
first event was a typical slow coronal mass ejection (CME), followed
∼7 h later by a smaller and collimated prominence eruption,
originating south of the CME, followed by a plasma blob. These
events were observed not only by the SOHO and STEREO-A missions,
but also by the suite of remote-sensing instruments on board Solar
Orbiter. <BR /> Aims: We show how data acquired by the Full Sun
Imager (FSI), the Metis coronagraph, and the Heliospheric Imager
(HI) from the Solar Orbiter perspective can be combined to study
the eruptions and different source regions. Moreover, we show how
Metis data can be analyzed to provide new information about solar
eruptions. <BR /> Methods: Different 3D reconstruction methods were
applied to the data acquired by different spacecraft, including
remote-sensing instruments on board Solar Orbiter. Images acquired
by the two Metis channels in the visible light (VL) and H I Ly-α
line (UV) were combined to derive physical information about the
expanding plasma. The polarization ratio technique was also applied
for the first time to Metis images acquired in the VL channel. <BR
/> Results: The two eruptions were followed in 3D from their source
region to their expansion in the intermediate corona. By combining
VL and UV Metis data, the formation of a post-CME current sheet (CS)
was followed for the first time in the intermediate corona. The
plasma temperature gradient across a post-CME blob propagating
along the CS was also measured for the first time. Application
of the polarization ratio technique to Metis data shows that by
combining four different polarization measurements, the errors are
reduced by ∼5 − 7%. This constrains the 3D plasma distribution
better. <P />Movies associated to Figs. 4-7 are available at <A
href="https://www.aanda.org/10.1051/0004-6361/202243162/olm">https://www.aanda.org</A>
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Title: Diagnostics of The Prominence Plasma Based on IRIS, H-alpha
and ALMA Observations
Authors: Berlicki, Arkadiusz; Bárta, Miroslav; Gunár, Stanislav;
Heinzel, Petr; Jejcic, Sonja; Radziszewski, Krzysztof; Rudawy, Pawel
2022cosp...44.2543B Altcode:
Solar prominences are now commonly observed above the solar limb in
different spectral bands and recent developments of new observing
techniques allow us to detect them from radio to far-UV ranges. In
addition to often used spectral observations in optical and UV,
ALMA interferometer obtained high-resolution images of a quiescent
solar prominence at 3 millimeters (Band 3) during the coordinated
space and ground-based observing campaign. For the first time
high-resolution observations of such structures in the millimeter
radio domain are available. The fine structures of this prominence was
also observed in the UV with IRIS and in the H$\alpha$ line with the
MSDP of Wroc{\l}aw Observatory. Both UV and H$\alpha$ data contains
not only images, but also spectra which makes the available dataset
extremely valuable. Moreover, all UV, H$\alpha$ and ALMA observations
are co-temporal which gives an unprecedented opportunity for a novel
diagnostic, not available so far. In this work we present analysis
of the prominence spectral characteristics in H$\alpha$ and UV Mg
II lines, looking for the statistical dependence between different
parameters (metrics) in the line profiles. This combined data is
then used for determination of plasma parameters in the prominence
fine structures. In addition, UV and H$\alpha$ spectral maps are
compared with the brightness temperature mosaics from ALMA, providing
an additional constraint on the plasma kinetic temperature. Detailed
diagnostics is then based on extensive NLTE numerical simulations of
the radiative transfer inside heterogeneous prominence structures.
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Title: Prominence eruption observed in He II 304 Å up to >6
R<SUB>⊙</SUB> by EUI/FSI aboard Solar Orbiter
Authors: Mierla, M.; Zhukov, A. N.; Berghmans, D.; Parenti, S.;
Auchère, F.; Heinzel, P.; Seaton, D. B.; Palmerio, E.; Jejčič, S.;
Janssens, J.; Kraaikamp, E.; Nicula, B.; Long, D. M.; Hayes, L. A.;
Jebaraj, I. C.; Talpeanu, D. -C.; D'Huys, E.; Dolla, L.; Gissot, S.;
Magdalenić, J.; Rodriguez, L.; Shestov, S.; Stegen, K.; Verbeeck,
C.; Sasso, C.; Romoli, M.; Andretta, V.
2022A&A...662L...5M Altcode: 2022arXiv220515214M
<BR /> Aims: We report observations of a unique, large prominence
eruption that was observed in the He II 304 Å passband of the Extreme
Ultraviolet Imager/Full Sun Imager telescope aboard Solar Orbiter on
15-16 February 2022. <BR /> Methods: Observations from several vantage
points - Solar Orbiter, the Solar-Terrestrial Relations Observatory,
the Solar and Heliospheric Observatory, and Earth-orbiting satellites -
were used to measure the kinematics of the erupting prominence and the
associated coronal mass ejection. Three-dimensional reconstruction was
used to calculate the deprojected positions and speeds of different
parts of the prominence. Observations in several passbands allowed us
to analyse the radiative properties of the erupting prominence. <BR />
Results: The leading parts of the erupting prominence and the leading
edge of the corresponding coronal mass ejection propagate at speeds
of around 1700 km s<SUP>−1</SUP> and 2200 km s<SUP>−1</SUP>,
respectively, while the trailing parts of the prominence are
significantly slower (around 500 km s<SUP>−1</SUP>). Parts of the
prominence are tracked up to heights of over 6 R<SUB>⊙</SUB>. The
He II emission is probably produced via collisional excitation rather
than scattering. Surprisingly, the brightness of a trailing feature
increases with height. <BR /> Conclusions: The reported prominence
is the first observed in He II 304 Å emission at such a great
height (above 6 R<SUB>⊙</SUB>). <P />Movies are available at <A
href="https://www.aanda.org/10.1051/0004-6361/202244020/olm">https://www.aanda.org</A>
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Title: Non-LTE Inversion of Prominence Spectroscopic Observations
in Hα and Mg II h&k lines
Authors: Jejčič, Sonja; Heinzel, Petr; Schmieder, Brigitte; Gunár,
Stanislav; Mein, Pierre; Mein, Nicole; Ruan, Guiping
2022ApJ...932....3J Altcode:
We continued our investigation of the plasma characteristics of a
quiescent prominence that occurred on 2017 March 30. The prominence
was observed simultaneously by several instruments, including the
Interface Region Imaging Spectrograph (IRIS) and the Multichannel
Subtractive Double Pass (MSDP) spectrograph operating at the Meudon
solar tower. We focused on IRIS Mg II h&k and MSDP Hα spectra,
selecting 55 well-coaligned points within the prominence. We computed
an extensive grid of 63,000 isothermal and isobaric 1D-slab prominence
models with a non-LTE (i.e., departures from the local thermodynamic
equilibrium) radiative transfer code. We then performed a 1.5D
spectral inversion searching for an optimal model that best fits
five parameters of the observed profiles (observables), namely,
the integrated intensity of the Hα and Mg II k lines, the FWHM of
both lines, and the ratio of intensities of the Mg II k and Mg II h
lines. The latter is sensitive to temperature. Our results show that
the prominence is a low-temperature structure, mostly below 10,000
K, with some excursions to higher values (up to 18,000 K) but also
rather low temperatures (around 5000 K). The microturbulent velocity is
typically low, peaking around 8 km s<SUP>-1</SUP>, and electron density
values are of the order of 10<SUP>10</SUP> cm<SUP>-3</SUP>. The peak
effective thickness is 500 km, although the values range up to 5000
km. The studied prominence is rather optically thin in the Hα line
and optically thick in the Mg II h&k lines.
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Title: Spectral inversion of H-alpha and MgII lines in quiescent
prominences
Authors: Heinzel, Petr; Schmieder, Brigitte; Ruan, Guiping; Mein,
Pierre; Gunár, Stanislav; Jejcic, Sonja; Mein, Nicole
2021cosp...43E1764H Altcode:
Recent spectral analysis of simultaneous H-alpha (MSDP) and MgII
lines (IRIS) (Guiping et al. 2019) has revealed certain bifurcation
in resulting models. Two solutions were found from the line inversions
using the non-LTE modeling: relatively high kinetic temperature and low
non-thermal motions or temperatures mostly compatible with standard ones
plus non-thermal motions of the order of 16 km/sec. Here we will present
an improved spectral line inversion technique which clearly prefers
the latter solution. Strong non-thermal motions are then interpreted
as a mixture of microturbulence and the line-of-sight dynamics of
prominence fine-structure threads. A detailed multithread modeling with
the 2D non-LTE code and stochastic distributions of threads (position,
dynamics) is now in progress and we will show our preliminary results.
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Title: IRIS Mg II Observations and Non-LTE Modeling of Off-limb
Spicules
Authors: Tei, A.; Gunár, S.; Heinzel, P.; Okamoto, T. J.; Štěpán,
J.; Jejčič, S.; Shibata, K.
2020AGUFMSH0010008T Altcode:
We investigated the off-limb spicules observed in the Mg II h and k
spectral lines by Interface Region Imaging Spectrograph (IRIS) in a
solar polar coronal hole. We analyzed the large data set of obtained
spectra to extract quantitative information about the line intensities,
line shifts, and line widths. The observed Mg II line profiles are
broad and double peaked at lower altitudes, broad but flat topped
at middle altitudes, and narrow and single peaked with the largest
Doppler shifts at higher altitudes. We used one-dimensional non-LTE
vertical slab models (i.e., models that consider departures from local
thermodynamic equilibrium) in single-slab and multi-slab configurations
to interpret the observations and to investigate how a superposition
of spicules along a line of sight (LOS) affects the synthetic Mg II
line profiles. The employed multi-slab models are either static,
i.e., without any LOS velocities, or assume randomly assigned LOS
velocities of individual slabs, representing the spicule dynamics. We
performed such single-slab and multi-slab modeling for a broad set of
model input parameters and examined the dependence of the Mg II line
profiles on these parameters. In this presentation, we demonstrate that
the observed line widths of the Mg h and k line profiles are strongly
affected by the presence of multiple spicules along the LOS. We also
show that the profiles obtained at higher altitudes can be reproduced
by single-slab models representing individual spicules. We found that
the multi-slab model with a random distribution of the LOS velocities
ranging from −25 to 25 km/s can well reproduce the width and the
shape of the Mg II profiles observed at middle altitudes.
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Title: Metis: the Solar Orbiter visible light and ultraviolet
coronal imager
Authors: Antonucci, Ester; Romoli, Marco; Andretta, Vincenzo; Fineschi,
Silvano; Heinzel, Petr; Moses, J. Daniel; Naletto, Giampiero; Nicolini,
Gianalfredo; Spadaro, Daniele; Teriaca, Luca; Berlicki, Arkadiusz;
Capobianco, Gerardo; Crescenzio, Giuseppe; Da Deppo, Vania; Focardi,
Mauro; Frassetto, Fabio; Heerlein, Klaus; Landini, Federico; Magli,
Enrico; Marco Malvezzi, Andrea; Massone, Giuseppe; Melich, Radek;
Nicolosi, Piergiorgio; Noci, Giancarlo; Pancrazzi, Maurizio; Pelizzo,
Maria G.; Poletto, Luca; Sasso, Clementina; Schühle, Udo; Solanki,
Sami K.; Strachan, Leonard; Susino, Roberto; Tondello, Giuseppe;
Uslenghi, Michela; Woch, Joachim; Abbo, Lucia; Bemporad, Alessandro;
Casti, Marta; Dolei, Sergio; Grimani, Catia; Messerotti, Mauro;
Ricci, Marco; Straus, Thomas; Telloni, Daniele; Zuppella, Paola;
Auchère, Frederic; Bruno, Roberto; Ciaravella, Angela; Corso,
Alain J.; Alvarez Copano, Miguel; Aznar Cuadrado, Regina; D'Amicis,
Raffaella; Enge, Reiner; Gravina, Alessio; Jejčič, Sonja; Lamy,
Philippe; Lanzafame, Alessandro; Meierdierks, Thimo; Papagiannaki,
Ioanna; Peter, Hardi; Fernandez Rico, German; Giday Sertsu, Mewael;
Staub, Jan; Tsinganos, Kanaris; Velli, Marco; Ventura, Rita; Verroi,
Enrico; Vial, Jean-Claude; Vives, Sebastien; Volpicelli, Antonio;
Werner, Stephan; Zerr, Andreas; Negri, Barbara; Castronuovo, Marco;
Gabrielli, Alessandro; Bertacin, Roberto; Carpentiero, Rita; Natalucci,
Silvia; Marliani, Filippo; Cesa, Marco; Laget, Philippe; Morea, Danilo;
Pieraccini, Stefano; Radaelli, Paolo; Sandri, Paolo; Sarra, Paolo;
Cesare, Stefano; Del Forno, Felice; Massa, Ernesto; Montabone, Mauro;
Mottini, Sergio; Quattropani, Daniele; Schillaci, Tiziano; Boccardo,
Roberto; Brando, Rosario; Pandi, Arianna; Baietto, Cristian; Bertone,
Riccardo; Alvarez-Herrero, Alberto; García Parejo, Pilar; Cebollero,
María; Amoruso, Mauro; Centonze, Vito
2020A&A...642A..10A Altcode: 2019arXiv191108462A
<BR /> Aims: Metis is the first solar coronagraph designed for a
space mission and is capable of performing simultaneous imaging of the
off-limb solar corona in both visible and UV light. The observations
obtained with Metis aboard the Solar Orbiter ESA-NASA observatory
will enable us to diagnose, with unprecedented temporal coverage and
spatial resolution, the structures and dynamics of the full corona
in a square field of view (FoV) of ±2.9° in width, with an inner
circular FoV at 1.6°, thus spanning the solar atmosphere from 1.7
R<SUB>⊙</SUB> to about 9 R<SUB>⊙</SUB>, owing to the eccentricity
of the spacecraft orbit. Due to the uniqueness of the Solar Orbiter
mission profile, Metis will be able to observe the solar corona
from a close (0.28 AU, at the closest perihelion) vantage point,
achieving increasing out-of-ecliptic views with the increase of the
orbit inclination over time. Moreover, observations near perihelion,
during the phase of lower rotational velocity of the solar surface
relative to the spacecraft, allow longer-term studies of the off-limb
coronal features, thus finally disentangling their intrinsic evolution
from effects due to solar rotation. <BR /> Methods: Thanks to a novel
occultation design and a combination of a UV interference coating of
the mirrors and a spectral bandpass filter, Metis images the solar
corona simultaneously in the visible light band, between 580 and 640
nm, and in the UV H I Lyman-α line at 121.6 nm. The visible light
channel also includes a broadband polarimeter able to observe the
linearly polarised component of the K corona. The coronal images in
both the UV H I Lyman-α and polarised visible light are obtained at
high spatial resolution with a spatial scale down to about 2000 km
and 15 000 km at perihelion, in the cases of the visible and UV light,
respectively. A temporal resolution down to 1 s can be achieved when
observing coronal fluctuations in visible light. <BR /> Results: The
Metis measurements, obtained from different latitudes, will allow for
complete characterisation of the main physical parameters and dynamics
of the electron and neutral hydrogen/proton plasma components of the
corona in the region where the solar wind undergoes the acceleration
process and where the onset and initial propagation of coronal mass
ejections (CMEs) take place. The near-Sun multi-wavelength coronal
imaging performed with Metis, combined with the unique opportunities
offered by the Solar Orbiter mission, can effectively address crucial
issues of solar physics such as: the origin and heating/acceleration
of the fast and slow solar wind streams; the origin, acceleration,
and transport of the solar energetic particles; and the transient
ejection of coronal mass and its evolution in the inner heliosphere,
thus significantly improving our understanding of the region connecting
the Sun to the heliosphere and of the processes generating and driving
the solar wind and coronal mass ejections. <BR /> Conclusions: This
paper presents the scientific objectives and requirements, the overall
optical design of the Metis instrument, the thermo-mechanical design,
and the processing and power unit; reports on the results of the
campaigns dedicated to integration, alignment, and tests, and to
the characterisation of the instrument performance; describes the
operation concept, data handling, and software tools; and, finally,
the diagnostic techniques to be applied to the data, as well as a brief
description of the expected scientific products. The performance of the
instrument measured during calibrations ensures that the scientific
objectives of Metis can be pursued with success. <P />Metis website:
<A href="http://metis.oato.inaf.it">http://metis.oato.inaf.it</A>
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Title: On the Possibility of Detecting Helium D3 Line Polarization
with Metis
Authors: Heinzel, Petr; Štěpán, Jiři; Bemporad, Alessandro;
Fineschi, Silvano; Jejčič, Sonja; Labrosse, Nicolas; Susino, Roberto
2020ApJ...900....8H Altcode: 2020arXiv200708940H
Metis, the space coronagraph on board the Solar Orbiter, offers us
new capabilities for studying eruptive prominences and coronal mass
ejections (CMEs). Its two spectral channels, hydrogen Lα and visible
light (VL), will provide for the first time coaligned and cotemporal
images to study dynamics and plasma properties of CMEs. Moreover,
with the VL channel (580-640 nm) we find an exciting possibility
to detect the helium D<SUB>3</SUB> line (587.73 nm) and its linear
polarization. The aim of this study is to predict the diagnostic
potential of this line regarding the CME thermal and magnetic
structure. For a grid of models we first compute the intensity of the
D<SUB>3</SUB> line together with VL continuum intensity due to Thomson
scattering on core electrons. We show that the Metis VL channel will
detect a mixture of both, with predominance of the helium emission at
intermediate temperatures between 30 and 50,000 K. Then we use the
code HAZEL to compute the degree of linear polarization detectable
in the VL channel. This is a mixture of D<SUB>3</SUB> scattering
polarization and continuum polarization. The former one is lowered in
the presence of a magnetic field and the polarization axis is rotated
(Hanle effect). Metis has the capability of measuring Q/I and U/I
polarization degrees and we show their dependence on temperature and
magnetic field. At T = 30,000 K we find a significant lowering of
Q/I which is due to strongly enhanced D<SUB>3</SUB> line emission,
while depolarization at 10 G amounts roughly to 10%.
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Title: Signatures of Helium Continuum in Cool Flare Loops Observed
by SDO/AIA
Authors: Heinzel, Petr; Schwartz, Pavol; Lörinčík, Juraj; Koza,
Július; Jejčič, Sonja; Kuridze, David
2020ApJ...896L..35H Altcode: 2020arXiv200600574H
We present an analysis of off-limb cool flare loops observed by the
Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA)
during the gradual phase of SOL2017-09-10T16:06 X8.2-class flare. In the
extreme-ultraviolet (EUV) channels starting from the 335 Å one, cool
loops appear as dark structures against the bright loop arcade. These
dark structures were precisely coaligned (spatially and temporally)
with loops observed by Swedish Solar Telescope (SST) in emission lines
of hydrogen and ionized calcium. A recently published semi-empirical
model of cool loops based on SST observations serves to predict the
level of hydrogen and helium recombination continua. The continua were
synthesized using an approximate non-LTE (I.e., departures from local
thermodynamic equilibrium) approach and theoretical spectra were then
transformed to AIA signals. Comparison with signals detected inside
the dark loops shows that only in AIA 211 Å channel the computed
level of recombination continua is consistent with observations for
some models, while in all other channels that are more distant from
the continua edges the synthetic continuum is far too low. In analogy
with on-disk observations of flares we interpret the surplus emission
as due to numerous EUV lines emitted from hot but faint loops in front
of the cool ones. Finally we briefly comment on failure of the standard
absorption model when used for analysis of the dark-loop brightness.
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Title: IRIS Mg II Observations and Non-LTE Modeling of Off-limb
Spicules in a Solar Polar Coronal Hole
Authors: Tei, Akiko; Gunár, Stanislav; Heinzel, Petr; Okamoto,
Takenori J.; Štěpán, Jiří; Jejčič, Sonja; Shibata, Kazunari
2020ApJ...888...42T Altcode: 2019arXiv191112243T
We investigated the off-limb spicules observed in the Mg II h and k
lines by IRIS in a solar polar coronal hole. We analyzed the large data
set of obtained spectra to extract quantitative information about the
line intensities, shifts, and widths. The observed Mg II line profiles
are broad and double peaked at lower altitudes, broad but flat topped
at middle altitudes, and narrow and single peaked with the largest
Doppler shifts at higher altitudes. We use one-dimensional non-LTE
vertical slab models (I.e., models that consider departures from local
thermodynamic equilibrium) in single-slab and multi-slab configurations
to interpret the observations and to investigate how a superposition
of spicules along the line of sight (LOS) affects the synthetic Mg
II line profiles. The used multi-slab models either are static, I.e.,
without any LOS velocities, or assume randomly assigned LOS velocities
of individual slabs, representing the spicule dynamics. We conducted
such single-slab and multi-slab modeling for a broad set of model
input parameters and showed the dependence of the Mg II line profiles
on these parameters. We demonstrated that the observed line widths
of the h and k line profiles are strongly affected by the presence
of multiple spicules along the LOS. We later showed that the profiles
obtained at higher altitudes can be reproduced by single-slab models
representing individual spicules. We found that the multi-slab model
with a random distribution of the LOS velocities ranging from -25 to
25 km s<SUP>-1</SUP> can well reproduce the width and the shape of Mg
II profiles observed at middle altitudes.
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Title: Diagnostics of the Prominence Plasma from Hα and Mg II
Spectral Observations
Authors: Ruan, Guiping; Jejčič, Sonja; Schmieder, Brigitte; Mein,
Pierre; Mein, Nicole; Heinzel, Petr; Gunár, Stanislav; Chen, Yao
2019ApJ...886..134R Altcode:
The goal of this paper is to derive the physical conditions of the
prominence observed on 2017 March 30. To do so, we use a unique set
of data in Mg II lines obtained with the space-borne Interface Region
Imaging Spectrograph (IRIS) and in Hα line with the ground-based
Multi-Channel Subtractive Double Pass spectrograph operating at the
Meudon solar tower. Here, we analyze the prominence spectra of Mg
II h and k lines, and the Hα line in the part of the prominence
which is visible in both sets of lines. We compute a grid of 1D
NLTE (i.e., departures from the local thermodynamical equilibrium)
models providing synthetic spectra of Mg II k and h, and Hα lines
in a large space of model input parameters (temperature, density,
pressure, and microturbulent velocity). We compare Mg II and Hα
line profiles observed in 75 positions of the prominence with the
synthetic profiles from the grid of models. These models allow us
to compute the relationships between the integrated intensities
and between the optical thickness in Hα and Mg II k lines. The
optical thickness τ <SUB>Hα </SUB> is between 0.05 and 2, and
{τ }<SUB>Mg</SUB>{{II}}{{k}}} is between 3 and 200. We show that
the relationship of the observed integrated intensities agrees well
with the synthetic integrated intensities for models with a higher
microturbulence (16 km s<SUP>-1</SUP>) and T around 8000 K, ne =
1.5 × 10<SUP>10</SUP> cm<SUP>-3</SUP>, p = 0.05 dyne. In this case,
large microturbulence values could be a way to take into account the
large mixed velocities existing in the observed prominence.
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Title: Spectral Diagnostics of Cool Flare Loops Observed by the
SST. I. Inversion of the Ca II 8542 Å and Hβ Lines
Authors: Koza, Július; Kuridze, David; Heinzel, Petr; Jejčič,
Sonja; Morgan, Huw; Zapiór, Maciej
2019ApJ...885..154K Altcode: 2019arXiv190907356K
Flare loops form an integral part of eruptive events, being detected in
the range of temperatures from X-rays down to cool chromospheric-like
plasmas. While hot loops are routinely observed by the Solar Dynamics
Observatory’s Atmospheric Imaging Assembly, cool loops seen
off-limb are rare. In this paper we employ unique observations of
the SOL2017-09-10T16:06 X8.2-class flare which produced an extended
arcade of loops. The Swedish 1 m Solar Telescope made a series of
spectral images of the cool off-limb loops in the Ca II 8542 Å and
the hydrogen Hβ lines. Our focus is on the loop apices. Non-local
thermal equilibrium (non-LTE; i.e., departures from LTE) spectral
inversion is achieved through the construction of extended grids of
models covering a realistic range of plasma parameters. The Multilevel
Accelerated Lambda Iterations code solves the non-LTE radiative-transfer
problem in a 1D externally illuminated slab, approximating the studied
loop segment. Inversion of the Ca II 8542 Å and Hβ lines yields two
similar solutions, both indicating high electron densities around 2 ×
10<SUP>12</SUP> cm<SUP>-3</SUP> and relatively large microturbulence
around 25 km s<SUP>-1</SUP>. These are in reasonable agreement with
other independent studies of the same or similar events. In particular,
the high electron densities in the range 10<SUP>12</SUP>-10<SUP>13</SUP>
cm<SUP>-3</SUP> are consistent with those derived from the Solar
Dynamics Observatory’s Helioseismic and Magnetic Imager white-light
observations. The presence of such high densities in solar eruptive
flares supports the loop interpretation of the optical continuum
emission of stars which manifest superflares.
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Title: Determination of the physical properties of an erupting
prominence from SOHO/LASCO and UVCS observations
Authors: Susino, R.; Bemporad, A.; Heinzel, P.; Jejčič, S.; Anzer,
, U.; Dzifčáková, E.
2019NCimC..42...37S Altcode:
We studied the physical conditions of an erupting prominence
observed in the core of a coronal mass ejection, using combination
of SOHO/LASCO-C2 visible-light images and SOHO/UVCS ultraviolet
data. Measured intensities and profiles of the neutral-hydrogen
Lyman- α and Lyman- β lines and the 977 Å C III line were
used together with the visible-light brightness to derive the
geometrical and physical parameters of the prominence, such as the
line-of-sight apparent thickness, electron column density, kinetic
temperature, and microturbolent velocity. These parameters were used
to constrain a non-LTE ( i.e., out of local thermodynamic equilibrium)
radiative-transfer model of the prominence that provides the effective
thickness, electron density, and flow velocity, in a sample of points
selected along the prominence. The prominence can be described as a hot
structure with low electron density and very low gas pressure compared
to typical quiescent prominences. Intensities of the hydrogen lines
were also used for a detailed determination of the plasma line-of-sight
filling factor, in the two prominence points where simultaneous and
cospatial LASCO-C2 and UVCS observations were available.
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Title: High-density Off-limb Flare Loops Observed by SDO
Authors: Jejčič, S.; Kleint, L.; Heinzel, P.
2018ApJ...867..134J Altcode: 2018arXiv181002431J
The density distribution of flare loops and the mechanisms of their
emission in the continuum are still open questions. On 2017 September
10, a prominent loop system appeared during the gradual phase of an X8.2
flare (SOL2017-09-10), visible in all passbands of SDO/AIA and in the
white-light continuum of SDO/HMI. We investigate its electron density
by taking into account all radiation processes in the flare loops,
i.e., the Thomson continuum, hydrogen Paschen and Brackett recombination
continua, as well as free-free continuum emission. We derive a quadratic
function of the electron density for a given temperature and effective
loop thickness. By absolutely calibrating SDO/HMI intensities,
we convert the measured intensities into electron density at each
pixel in the loops. For a grid of plausible temperatures between cool
(6000 K) and hot (10<SUP>6</SUP> K) structures, the electron density
is computed for representative effective thicknesses between 200 and
20,000 km. We obtain a relatively high maximum electron density, about
10<SUP>13</SUP> cm<SUP>-3</SUP>. At such high electron densities, the
Thomson continuum is negligible and therefore one would not expect a
significant polarization degree in dense loops. We conclude that the
Paschen and Brackett recombination continua are dominant in cool flare
loops, while the free-free continuum emission is dominant for warmer
and hot loops.
---------------------------------------------------------
Title: Statistical analysis of UV spectra of a quiescent prominence
observed by IRIS
Authors: Jejčič, S.; Schwartz, P.; Heinzel, P.; Zapiór, M.;
Gunár, S.
2018A&A...618A..88J Altcode: 2018arXiv180705767J
Context. The paper analyzes the structure and dynamics of a quiescent
prominence that occurred on October 22, 2013 and was observed by
several instruments including the Interface Region Imaging Spectrograph
(IRIS). <BR /> Aims: We aim to determine the physical characteristics
of the observed prominence using Mg II k and h (2796 and 2803 Å), C
II (1334 and 1336 Å), and Si IV (1394 Å) lines observed by IRIS. In
addition we study the dynamical behavior of the prominence. <BR />
Methods: We employed the one-dimensional non-LTE (departures from the
local thermodynamic equilibrium - LTE) modeling of Mg II lines assuming
static isothermal-isobaric slabs. We selected a large grid of models
with realistic input parameters expected for quiescent prominences
(temperature, gas pressure, effective thickness, microturbulent
velocity, height above the solar surface) and computed synthetic Mg II
lines. The method of Scargle periodograms was used to detect possible
prominence oscillations. <BR /> Results: We analyzed 2160 points of the
observed prominence in five different sections along the slit averaged
over ten pixels due to low signal to noise ratio in the C II and Si IV
lines. We computed the integrated intensity for all studied lines, while
the central intensity and reversal ratio was determined only for both Mg
II and C II 1334 lines. We plotted several correlations: time evolution
of the integrated intensities and central intensities, scatter plots
between all combinations of line integrated intensities, and reversal
ratio as a function of integrated intensity. We also compared Mg II
observations with the models. Results show that more than two-thirds
of Mg II profiles and about one-half of C II 1334 profiles are
reversed. Profiles of Si IV are generally unreversed. The Mg II and C II
lines are optically thick, while the Si IV line is optically thin. <BR
/> Conclusions: The studied prominence shows no global oscillations
in the Mg II and C II lines. Therefore, the observed time variations
are caused by random motions of fine structures with velocities up
to 10 km s<SUP>-1</SUP>. The observed average ratio of Mg II k to
Mg II h line intensities can be used to determine the prominence's
characteristic temperature. Certain disagreements between observed
and synthetic line intensities of Mg II lines point to the necessity
of using more complex two-dimensional multi-thread modeling in the
future. <P />The movies associated to Figs. 1 and 7 are available at <A
href="https://www.aanda.org/10.1051/0004-6361/201833466/olm">https://www.aanda.org</A>
---------------------------------------------------------
Title: Hot prominence detected in the core of a coronal mass
ejection. III. Plasma filling factor from UVCS Lyman-α and Lyman-β
observations
Authors: Susino, R.; Bemporad, A.; Jejčič, S.; Heinzel, P.
2018A&A...617A..21S Altcode: 2018arXiv180512465S
Context. We study an erupting prominence embedded in the core of a
coronal mass ejection that occurred on August 2, 2000, and focus on
deriving the plasma filling factor of the prominence. <BR /> Aims:
We explore two methods for measuring this factor along the line of
sight. They are based on a combination of visible-light and ultraviolet
spectroscopic observations. <BR /> Methods: Theoretical relationships
for resonant scattering and collisional excitation were used to evaluate
the intensity of the neutral hydrogen Lyman-α and Lyman-β lines in
two prominence points where simultaneous and cospatial LASCO-C2 and
UVCS data were available. Thermodynamic and geometrical parameters
assumed for the calculation (i.e., electron column density, kinetic
temperature, flow velocity, chromospheric Lyα and Lyβ intensities
and profiles, and thickness of the prominence along the line of sight)
are provided by both observations and the results of a detailed 1D
non-local thermal equilibrium (non-LTE) radiative-transfer model
of the prominence, developed in our previous work. The geometrical
filling factor was derived from comparing the calculated and measured
intensities of the two lines. The results were then checked against the
non-LTE model in order to verify the reliability of the methods. <BR />
Results: The resulting filling factors are consistent with the model in
both prominence points when the radiative and collisional components
of the total intensity of the hydrogen lines are separated using
the Lyα and Lyβ line intensities, which is required to estimate
the filling factor. The exploration of the parameter space shows
that the results are weakly sensitive to the plasma flow velocity,
but depend more strongly on the assumed kinetic temperatures. <BR />
Conclusions: The combination of visible-light and ultraviolet Lyα
and Lyβ data can be used to approximately estimate the line-of-sight
geometrical filling factor in erupting prominences, but the proposed
technique, which is model dependent, is reliable only for emission
that is optically thin in the lines considered, a condition that is
not in general representative of prominence plasma.
---------------------------------------------------------
Title: Plasma physical parameters of a prominence embedded in the
core of a Coronal Mass Ejection
Authors: Bemporad, Alessandro; Anzer, Ulrich; Heinzel, Petr; Jejcic,
Sonja; Susino, Roberto
2018cosp...42E.267B Altcode:
We determine the plasma physical parameters of an erupting prominence
embedded in the core of a CME, combininging visible light coronagraphic
images from SOHO/LASCO with UV spectra acquired by SOHO/UVCS. Strong
UV emissions were detected in the hydrogen Lyman-α and Lyman-β
lines and C III line. Visible light and UV intensities have been used
to estimate the projected thickness and velocity of the prominence,
together with the effective plasma temperature, microturbolent velocity,
and column density. These parameters have been used to constrain
1D NLTE modeling of the erupting plasma, taking into account the
effects of large flow velocities (Doppler dimming). Roughly one-half
of considered points in the prominence body show a non-negligible
Lyman-α optical thickness. Comparison between the calculated and the
measured intensities of the two Lyman lines was also used to derive the
geometrical filling factor. Results show that the erupting prominence
plasma is relatively hot, with a low electron density, a wide range of
effective thicknesses, a rather narrow range of radial flow velocities,
and a microturbulence of about 25 km/s. This analysis provides a basis
for future diagnostics of prominences using the METIS coronagraph on
board the Solar Orbiter mission.
---------------------------------------------------------
Title: Hot Erupting Prominences in Cores of Cme's
Authors: Heinzel, Petr; Bemporad, Alessandro; Anzer, Ulrich; Jejcic,
Sonja; Susino, Roberto; Dzifcakova, Elena
2018cosp...42E1421H Altcode:
Coronal mass ejections (CME) associated with prominence eruptions
exhibit relatively coolmaterial in their cores. Such prominence
plasmas were frequently detected in various spectrallines by SOHO/UVCS
coronagraph and in the visible light by SOHO/LASCO as well as bySTEREO
coronagraphs. UVCS provided excellent spectra of CME-core prominences
and anextended catalogue of these data is available. We will present
recent results of a hot prominence diagnostics using the hydrogen Lyman
lines and the CIII line . The erupting prominence parameters are further
constrained by the visible light observations from LASCO-C2. A novel
non-LTE modeling based on such observations will be presented and we
will highlight the diagnostic potential of the UV and visible light for
future space coronagraphs like Metis on board the ESA Solar Orbiter
mission. The plasma parameters of such hot prominences are compared
with those obtained from numerical MHD simulations of erupting flux
ropes surrounded by CMEs. Finally, we will also mention synergies with
stellar analogues.
---------------------------------------------------------
Title: Visibility of Prominences Using the He I D<SUB>3</SUB> Line
Filter on the PROBA-3/ASPIICS Coronagraph
Authors: Jejčič, S.; Heinzel, P.; Labrosse, N.; Zhukov, A. N.;
Bemporad, A.; Fineschi, S.; Gunár, S.
2018SoPh..293...33J Altcode: 2018arXiv180700155J
We determine the optimal width and shape of the narrow-band filter
centered on the He I D<SUB>3</SUB> line for prominence and coronal
mass ejection (CME) observations with the ASPIICS (Association of
Spacecraft for Polarimetric and Imaging Investigation of the Corona of
the Sun) coronagraph onboard the PROBA-3 (Project for On-board Autonomy)
satellite, to be launched in 2020. We analyze He I D<SUB>3</SUB> line
intensities for three representative non-local thermal equilibrium
prominence models at temperatures 8, 30, and 100 kK computed with a
radiative transfer code and the prominence visible-light (VL) emission
due to Thomson scattering on the prominence electrons. We compute
various useful relations at prominence line-of-sight velocities of 0,
100, and 300 km s<SUP>−1</SUP> for 20 Å wide flat filter and three
Gaussian filters with a full-width at half-maximum (FWHM) equal to 5,
10, and 20 Å to show the relative brightness contribution of the He I
D<SUB>3</SUB> line and the prominence VL to the visibility in a given
narrow-band filter. We also discuss possible signal contamination by Na
I D<SUB>1</SUB> and D<SUB>2</SUB> lines, which otherwise may be useful
to detect comets. Our results mainly show that i) an optimal narrow-band
filter should be flat or somewhere between flat and Gaussian with an
FWHM of 20 Å in order to detect fast-moving prominence structures,
ii) the maximum emission in the He I D<SUB>3</SUB> line is at 30 kK
and the minimal at 100 kK, and iii) the ratio of emission in the He I
D<SUB>3</SUB> line to the VL emission can provide a useful diagnostic
for the temperature of prominence structures. This ratio is up to 10
for hot prominence structures, up to 100 for cool structures, and up
to 1000 for warm structures.
---------------------------------------------------------
Title: Hot prominence detected in the core of a coronal mass
ejection. II. Analysis of the C III line detected by SOHO/UVCS
Authors: Jejčič, S.; Susino, R.; Heinzel, P.; Dzifčáková, E.;
Bemporad, A.; Anzer, U.
2017A&A...607A..80J Altcode:
Context. We study the physics of erupting prominences in the core
of coronal mass ejections (CMEs) and present a continuation of a
previous analysis. <BR /> Aims: We determine the kinetic temperature
and microturbulent velocity of an erupting prominence embedded in the
core of a CME that occurred on August 2, 2000 using the Ultraviolet
Coronagraph and Spectrometer observations (UVCS) on board the Solar
and Heliospheric Observatory (SOHO) simultaneously in the hydrogen
Lα and C III lines. We develop the non-LTE (departures from the local
thermodynamic equilibrium - LTE) spectral diagnostics based on Lα and
Lβ measured integrated intensities to derive other physical quantities
of the hot erupting prominence. Based on this, we synthesize the C
III line intensity to compare it with observations. <BR /> Methods:
Our method is based on non-LTE modeling of eruptive prominences. We
used a general non-LTE radiative-transfer code only for optically thin
prominence points because optically thick points do not allow the
direct determination of the kinetic temperature and microturbulence
from the line profiles. The input parameters of the code were the
kinetic temperature and microturbulent velocity derived from the Lα
and C III line widths, as well as the integrated intensity of the Lα
and Lβ lines. The code runs in three loops to compute the radial flow
velocity, electron density, and effective thickness as the best fit
to the Lα and Lβ integrated intensities within the accuracy defined
by the absolute radiometric calibration of UVCS data. <BR /> Results:
We analyzed 39 observational points along the whole erupting prominence
because for these points we found a solution for the kinetic temperature
and microturbulent velocity. For these points we ran the non-LTE code to
determine best-fit models. All models with τ<SUB>0</SUB>(Lα) ≤ 0.3
and τ<SUB>0</SUB>(C III) ≤ 0.3 were analyzed further, for which we
computed the integrated intensity of the C III line using a two-level
atom. The best agreement between computed and observed integrated
intensity led to 30 optically thin points along the prominence. The
results are presented as histograms of the kinetic temperature,
microturbulent velocity, effective thickness, radial flow velocity,
electron density, and gas pressure. We also show the relation between
the microturbulence and kinetic temperature together with a scatter plot
of computed versus observed C III integrated intensities and the ratio
of the computed to observed C III integrated intensities versus kinetic
temperature. <BR /> Conclusions: The erupting prominence embedded in
the CME is relatively hot with a low electron density, a wide range of
effective thicknesses, a rather narrow range of radial flow velocities,
and a microturbulence of about 25 km s<SUP>-1</SUP>. This analysis shows
a disagreement between observed and synthetic intensities of the C III
line, the reason for which most probably is that photoionization is
neglected in calculations of the ionization equilibrium. Alternatively,
the disagreement might be due to non-equilibrium processes.
---------------------------------------------------------
Title: Hot prominence detected in the core of a coronal mass ejection:
Analysis of SOHO/UVCS Lα and SOHO/LASCO visible-light observations
Authors: Heinzel, P.; Susino, R.; Jejčič, S.; Bemporad, A.; Anzer, U.
2016A&A...589A.128H Altcode:
Context. The paper deals with the physics of erupting prominences in
the core of coronal mass ejections (CME). <BR /> Aims: We determine the
physical parameters of an erupting prominence embedded in the core of a
CME using SOHO/UVCS hydrogen Lα and Lβ lines and SOHO/LASCO visible
light observations. In particular we analyze the CME event observed
on August 2, 2000. We develop the non-LTE (NLTE; I.e. considering
departures from the local thermodynamic equilibrium - LTE) spectral
diagnostics based on Lα and visible light observations. <BR /> Methods:
Our method is based on 1D NLTE modeling of eruptive prominences and
takes into account the effect of large flow velocities, which reach
up to 300 km s<SUP>-1</SUP> for the studied event (the so-called
Doppler dimming). The NLTE radiative-transfer method can be used
for both optically thin and thick prominence structures. We combine
spectroscopic UVCS observations of an erupting prominence in the core
of a CME with visible light images from LASCO-C2 in order to derive the
geometrical parameters like projected thickness and velocity, together
with the effective temperature and column density of electrons. These
are then used to constrain our NLTE radiative transfer modeling which
provides the kinetic temperature, microturbulent velocity, gas pressure,
ionization degree, the line opacities, and the prominence effective
thickness (geometrical filling factor). <BR /> Results: Analysis was
made for 69 observational points (spatial pixels) inside the whole
erupting prominence. Roughly one-half of them show a non-negligible Lα
optical thickness for flow velocity 300 km s<SUP>-1</SUP> and about
one-third for flow velocity 150 km s<SUP>-1</SUP>. All pixels with
Lατ<SUB>0</SUB> ≤ 0.3 have been considered for further analysis,
which is presented in the form of statistical distributions (histograms)
of various physical quantities such as the kinetic temperature, gas
pressure, and electron density for two representative flow velocities
(150 and 300 km s<SUP>-1</SUP>) and non-zero microturbulence. For
two pixels co-temporal LASCO visible-light data are also available,
which further constrains the diagnostics of the electron density and
effective thickness. Detailed NLTE modeling is presented for various
sets of input parameters. <BR /> Conclusions: The studied CME event
shows that the erupting prominence expands to large volumes, meaning
that it is a low-pressure structure with low electron densities and
high temperatures. This analysis provides a basis for future diagnostics
using the METIS coronagraph on board the Solar Orbiter mission.
---------------------------------------------------------
Title: Is it Possible to Use the Green Coronal Line Instead of X rays
to Cancel an Effect of the Coronal Emissivity Deficit in Estimation of
the Prominence Total Mass from Decrease of the EUV-corona Intensities?
Authors: Schwartz, P.; Heinzel, P.; Jejčič, S.; Rybák, J.; Kotrč,
P.; Fárník, F.; Kupryakov, Yu. A.; Deluca, E. E.; Golub, L.; Jibben,
P. R.; Anzer, U.; Tlatov, A. G. .; Guseva, S. A.
2016ASPC..504...89S Altcode:
Total masses of six quiescent prominences observed from April through
June 2011 were estimated using multi-spectral observations (in EUV,
X-rays, Hα, and Ca <small>II</small> H). The method for
the total mass estimation is based on the fact that the intensity
of the EUV solar corona at wavelengths below 912 Å is reduced at a
prominence by the absorption in resonance continua (photoionisation)
of hydrogen and possibly by helium and subsequently an amount of
absorbed radiation is proportional to the column density of hydrogen
and helium plasma. Moreover, the deficit of the coronal emissivity in
volume occupied by the cool prominence plasma also contributes to the
intensity decrease. The observations in X-rays which are not absorbed
by the prominence plasma, allow us to separate these two mechanisms
from each other. The X-ray observations of XRT onboard the Hinode
satellite made with the Al-mesh focal filter were used because the
X-ray coronal radiation formed in plasma of temperatures of the order
of 10<SUP>6</SUP> K was registered and EUV spectral lines occurring in
the 193, 211 and 335 Å channels of the Atmospheric Imaging Assembly
of the Solar Dynamics Observatory satellite are also formed at such
temperatures. Unfortunately, the Al-mesh filter has a secondary peak
of the transmittance at around 171 Å which causes a contribution
from the EUV corona to the measured data of up to 11 % in the quiet
corona. Thus, absorption in prominence plasma influences XRT X-ray
data when using the Al-mesh filter. On the other hand, other X-ray XRT
filters are more sensitive to plasma of much higher temperatures (log
T of the order of 7), thus observations using these filters cannot
be used together with the AIA observations in the method for mass
estimations. This problem could be solved using observations in the
green coronal line instead of X-rays. Absorption of the green coronal
line by a prominence plasma is negligible and this line is formed at
temperatures of the order of 10<SUP>6</SUP> K. We compare values of
the total mass of the prominence observed on 20 October 2012 on the
SE limb estimated when using XRT X-ray observations and observations
in the green coronal line obtained at Kislovodsk Mountain Astronomical
Station of the Pulkovo observatory (Russia).
---------------------------------------------------------
Title: Prominence Visibility in Hinode/XRT Images
Authors: Schwartz, P.; Jejčič, S.; Heinzel, P.; Anzer, U.; Jibben,
P. R.
2015ApJ...807...97S Altcode: 2015arXiv150606078S
In this paper we study the soft X-ray (SXR) signatures of one
particular prominence. The X-ray observations used here were made by the
Hinode/X-Ray Telescope instrument using two different filters. Both of
them have a pronounced peak of the response function around 10 Å. One
of them has a secondary smaller peak around 170 Å, which leads to a
contamination of SXR images. The observed darkening in both of these
filters has a very large vertical extension. The position and shape of
the darkening correspond nicely with the prominence structure seen in
SDO/AIA images. First, we have investigated the possibility that the
darkening is caused by X-ray absorption. However, detailed calculations
of the optical thickness in this spectral range show clearly that
this effect is completely negligible. Therefore, the alternative is
the presence of an extended region with a large emissivity deficit,
which can be caused by the presence of cool prominence plasmas within
an otherwise hot corona. To reproduce the observed darkening, one needs
a very large extension along the line of sight of the region amounting
to around 10<SUP>5</SUP> km. We interpret this region as the prominence
spine, which is also consistent with SDO/AIA observations in EUV.
---------------------------------------------------------
Title: Multi-Wavelength Eclipse Observations of a Quiescent Prominence
Authors: Jejčič, S.; Heinzel, P.; Zapiór, M.; Druckmüller, M.;
Gunár, S.; Kotrč, P.
2014SoPh..289.2487J Altcode: 2014SoPh..tmp...30J
We construct the maps of temperatures, geometrical thicknesses,
electron densities and gas pressures in a quiescent prominence. For
this we use the RGB signal of the prominence visible-light emission
detected during the total solar eclipse of 1 August 2008 in Mongolia
and quasi-simultaneous Hα spectra taken at Ondřejov Observatory. The
method of disentangling the electron density and geometrical (effective)
thickness was described by Jejčič and Heinzel (Solar Phys.254,
89 - 100, 2009) and is used here for the first time to analyse
the spatial variations of prominence parameters. For the studied
prominence we obtained the following range of parameters: temperature
6000 - 15 000 K, effective thickness 200 - 15000 km, electron density
5×10<SUP>9</SUP> - 10<SUP>11</SUP> cm<SUP>−3</SUP> and gas pressure
0.02 - 0.2 dyn cm<SUP>−2</SUP> (assuming a fixed ionisation degree
n<SUB>p</SUB>/n<SUB>H</SUB>=0.5). The electron density increases
towards the bottom of the prominence, which we explain by an enhanced
photoionisation due to the incident solar radiation. To confirm this,
we construct a two-dimensional radiative-transfer model with realistic
prominence illumination.
---------------------------------------------------------
Title: A study of H I Lyman-alpha emission from prominences erupting
in the intermediate corona and possible future applications for
Solar Orbiter/METIS data
Authors: Bemporad, Alessandro; Heinzel, Petr; Jejcic, Sonja; Susino,
Roberto
2014cosp...40E.273B Altcode:
Over almost the last 20 years hundreds of Coronal Mass Ejections
(CME) have been observed by the UV Coronagraph Spectrometer (UVCS)
onboard SOHO. For many of these events a significant emission in the HI
Lyman-alpha lambda 1216 Å line was sampled during the transit across
the slit of the erupting prominences embedded in the core of CMEs. The
origin of this emission is completely different from what is typically
observed by UVCS: because of the higher density and lower temperatures
of such plasmas, the number of neutral H atoms is much larger than
under typical coronal conditions, and the plasma is generally not
optically thin at these wavelengths, as it is usually true for other
coronal structures. Hence, the observed H I Lyman-alpha emission can be
explained only if a radiative transport treatment across a moving plasma
structure is considered. Once the proper boundary conditions are derived
from the UV data, in combination with white light (WL) coronagraphic
observations (from LASCO), we will show how the temperature and
density of the erupting prominence could be derived even at large
altitudes (typically larger than 0.6 solar radii above the limb),
thus providing information on heating/cooling and ionization of the
CME core during the eruption. These results are very important in the
light of coronagraphic observations that will be provided by the METIS
instrument onboard the Solar Orbiter: because METIS will contemporary
observe the solar corona in WL and in UV (HI Lyman-alpha), it will be
possible to derive, with a technique similar to what is shown here,
very important information on prominence plasmas embedded in the core
of CMEs and crossing the METIS instrument field of view.
---------------------------------------------------------
Title: Mapping prominence plasma parameters from eclipse observations
Authors: Jejčič, Sonja; Heinzel, Petr; Zapiór, Maciej; Druckmüller,
Miloslav; Gunár, Stanislav; Kotrč, Pavel
2014IAUS..300..420J Altcode:
Using the eclipse observations, we construct the maps of quiescent
prominence temperatures, electron densities, pressures and geometrical
thicknesses. For this we use the RGB signal of prominence visible-light
emission detected during the total solar eclipse on August 1, 2008
in Mongolia, and quasi-simultaneous Hα spectra taken at Ondřejov
observatory. The method of disentangling the electron density and
effective geometrical thickness was described by Jejčič &
Heinzel (2009) and is used here for the first time to analyse the
spatial variations of various prominence parameters.
---------------------------------------------------------
Title: Electron Densities in Quiescent Prominences Derived from
Eclipse Observations
Authors: Jejčič, S.; Heinzel, P.
2009SoPh..254...89J Altcode:
We develop a diagnostic tool for determination of the electron
densities in solar prominences using eclipse data. The method is based
on analysis of the hydrogen Balmer-line intensities (namely Hα and
Hβ) and the white-light emission due to Thomson scattering on the
prominence electrons. Our approach represents a generalization of
the ratio method already used by Koutchmy, Lebecq, and Stellmacher
(Astron. Astrophys.119, 261, 1983). In this paper we use an extended
grid of non-LTE prominence models of Gouttebroze, Heinzel, and Vial
(Astron. Astrophys. Suppl. Ser.99, 513, 1993) and derive various
useful relations between prominence radiation properties and electron
densities. Simultaneously, an effective geometrical thickness of the
prominence can also be obtained. As an example we apply our general
technique to original eclipse data of Koutchmy, Lebecq, and Stellmacher
(Astron. Astrophys.119, 261, 1983). Finally, we use our results to
determine the color of prominences as it should be seen during total
eclipses.
---------------------------------------------------------
Title: Eclipse Observations of Quiescent Prominences
Authors: Jejcic, S.; Heinzel, P.; Kotrc, P.; Druckmuller, M.
2008ESPM...12.2.66J Altcode:
In this study we demonstrate how to analyze the solar eclipse data
taken by a digital camera. We use the observations of a quiescent
prominence obtained during the total solar eclipse on March 29, 2006
(Side, Turkey). Using the RGB signal of the white light emission
and co-temporal H? spectra taken at Ondrejov Observatory, we derive
the electron density, temperature and geometrical thickness of the
studied prominence.
---------------------------------------------------------
Title: White-Light Emission of Solar Prominences
Authors: Jejčič, S.; Heinzel, P.
2007ASPC..368..325J Altcode:
Using an extended grid of prominence models we compute the prominence
white-light (WL) emission due to Thomson scattering and compare it
with that in Hα. The ratio of the WL emission and the total emission
can explain the color of prominences as observed during the total
eclipses and can tell us whether the pink color of prominences is due
to their intrinsic white-light emission or due to coronal contribution
at the prominence location. We also show how this ratio depends on
the prominence electron density, temperature and thickness.
---------------------------------------------------------
Title: Popolni Soncev mrk v Turciji, 29. marec 2006, Side, Turcija
---------------------------------------------------------
Title: Popolni Soncev mrk v Turciji, 29. marec 2006, Side, Turcija
---------------------------------------------------------
Title: Total Solar Eclipse in Turkey, March 29th, 2006, Side, Turkey.
Authors: Jejcic, S.; Dintinjana, B.; Mikuz, H.
2006Spika..14..186J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Comparison of Spectroscopic Measurements of the Solar
Rotation
Authors: Jejčič, S.; Čadež, A.
2005HvaOB..29...11J Altcode:
We studied the velocity field on the surface of the Sun measured by
the Doppler shift of Fraunhofer Sodium lines Na-D_{2} at 5891.583 Å,
Na-D_{1} at 5897.557 Å and Nickel line Ni I at 5894.505 Å. All
the spectroscopic measurements were done at Ljubljana observatory
on September 9, 10, 13 and 14 1999 using double monochromator
DFS-12. The calibration was done through five telluric water lines
in the vicinity of Sodium lines. With respect to telluric water lines
Fraunhofer lines were analysed and through their Doppler velocity we
determined the velocity field on the surface of the Sun. The data were
fitted to the rotation model to determine the average solar angular
(sidereal) coefficients, the average gravitational redshift velocity
and the average parameters of the systematic limb shift for each line
separately. Solar rotation coefficients determined by our measurements
are compared with those of Howard and Harvey, Snodgrass and Ulrich,
and Wittmann.
---------------------------------------------------------
Title: Final Results of the VT-2004 International Project /Koncni
rezultati mednarodnega projekta VT-2004
Authors: Jejcic, S.
2005Spika..13...38J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: CCD Spectroscopy of Solar Rotation
Authors: Jejčič, S.; Čadež, A.
2005ASSL..320..271J Altcode: 2005smp..conf..271J
No abstract at ADS
---------------------------------------------------------
Title: Venus Transit 2004/Prehod Venere 2004 - Venera bo 8. junija
2004 preckala Soncevo ploskev
Authors: Jejcic, S.; Cadez, A.
2004Spika..12..206J Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Velocity measurements by the double monochromator DFS-12
Authors: Jejčič, S.; Čadež, A.
2003HvaOB..27..197J Altcode:
This study presents the observation of the velocity field on the surface
of the Sun, measured by the Doppler shift of sodium D lines in the solar
spectrum calibrated by the telluric water line. The observations were
made on 9 September 1999 by the double monochromator DFS-12 at Ljubljana
observatory. The data were used with a rotation model to determine
the parameters of solar angular velocity, the gravitational redshift
velocity as well as the parameters of the systematic limb shift.
---------------------------------------------------------
Title: Observations of velocity field on the surface of the sun
Authors: Jejčič, S.; Čadež, A.
2002ESASP.506..959J Altcode: 2002ESPM...10..959J; 2002svco.conf..959J
We studied the solar Doppler velocity field by scanning the
frequency of sodium lines across the solar disk. We describe the
double monochromator used for this task and discuss data reduction and
calibration procedures. The data obtained during summer 1999 were used
with a rotation model to determine two components of solar angular
velocity, the gravitational redshift as well as an approximation to
differential rotation.
