explanation blue bibcodes open ADS page with paths to full text
Author name code: bocchialini
ADS astronomy entries on 2022-09-14
author:"Bocchialini, Karine"
---------------------------------------------------------
Title: The role of asymmetries in coronal rain formation during
thermal non-equilibrium cycles
Authors: Pelouze, Gabriel; Auchère, Frédéric; Bocchialini, Karine;
Froment, Clara; Mikić, Zoran; Soubrié, Elie; Voyeux, Alfred
2022A&A...658A..71P Altcode: 2021arXiv211009975P
Context. Thermal non-equilibrium (TNE) produces several observables
that can be used to constrain the spatial and temporal distribution
of solar coronal heating. Its manifestations include prominence
formation, coronal rain, and long-period intensity pulsations in
coronal loops. The recent observation of abundant periodic coronal rain
associated with intensity pulsations allowed for these two phenomena
to be unified as the result of TNE condensation and evaporation
cycles. On the other hand, many observed intensity pulsation events
show little to no coronal rain formation. <BR /> Aims: Our goal is
to understand why some TNE cycles produce such abundant coronal
rain, while others produce little to no rain. <BR /> Methods:
We reconstructed the geometry of the periodic coronal rain event,
using images from the Extreme Ultraviolet Imager (EUVI) onboard the
Solar Terrestrial Relations Observatory (STEREO), and magnetograms
from the Helioseismic and Magnetic Imager (HMI). We then performed 1D
hydrodynamic simulations of this event for different heating parameters
and variations of the loop geometry (9000 simulations in total). We
compared the resulting behaviour to simulations of TNE cycles that do
not produce coronal rain. <BR /> Results: Our simulations show that
both prominences and TNE cycles (with and without coronal rain) can
form within the same magnetic structure. We show that the formation
of coronal rain during TNE cycles depends on the asymmetry of the
loop and of the heating. Asymmetric loops are overall less likely
to produce coronal rain, regardless of the heating. In symmetric
loops, coronal rain forms when the heating is also symmetric. In
asymmetric loops, rain forms only when the heating compensates for
the asymmetry. <P />Movie associated to Fig. 5 is available at <A
href="https://www.aanda.org/10.1051/0004-6361/202140477/olm">https://www.aanda.org</A>
---------------------------------------------------------
Title: Empirical relations between the intensities of Lyman lines
of H and He<SUP>+</SUP>
Authors: Gordino, M.; Auchère, F.; Vial, J. -C.; Bocchialini, K.;
Hassler, D. M.; Bando, T.; Ishikawa, R.; Kano, R.; Kobayashi, K.;
Narukage, N.; Trujillo Bueno, J.; Winebarger, A.
2022A&A...657A..86G Altcode: 2022arXiv220101519G
Context. Empirical relations between major UV and extreme UV spectral
lines are one of the inputs for models of chromospheric and coronal
spectral radiances and irradiances. They are also needed for the
interpretation of some of the observations of the Solar Orbiter
mission. <BR /> Aims: We aim to determine an empirical relation between
the intensities of the H I 121.6 nm and He II 30.4 nm Ly-α lines. <BR
/> Methods: Images at 121.6 nm from the Chromospheric Lyman-Alpha
Spectro Polarimeter (CLASP) and Multiple XUV Imager (MXUVI) sounding
rockets were co-registered with simultaneous images at 30.4 nm from the
EIT and AIA orbital telescopes in order to derive a spatially resolved
relationship between the intensities. <BR /> Results: We have obtained
a relationship between the H I 121.6 nm and He II 30.4 nm intensities
that is valid for a wide range of solar features, intensities, and
activity levels. Additional SUMER data have allowed the derivation of
another relation between the H I 102.5 nm (Ly-β) and He II 30.4 nm
lines for quiet-Sun regions. We combined these two relationships to
obtain a Ly-α/Ly-β intensity ratio that is comparable to the few
previously published results. <BR /> Conclusions: The relationship
between the H I 121.6 nm and He II 30.4 nm lines is consistent with the
one previously obtained using irradiance data. We have also observed
that this relation is stable in time but that its accuracy depends on
the spatial resolution of the observations. The derived Ly-α/Ly-β
intensity ratio is also compatible with previous results.
---------------------------------------------------------
Title: The Solar Orbiter Science Activity Plan. Translating solar
and heliospheric physics questions into action
Authors: Zouganelis, I.; De Groof, A.; Walsh, A. P.; Williams, D. R.;
Müller, D.; St Cyr, O. C.; Auchère, F.; Berghmans, D.; Fludra,
A.; Horbury, T. S.; Howard, R. A.; Krucker, S.; Maksimovic, M.;
Owen, C. J.; Rodríguez-Pacheco, J.; Romoli, M.; Solanki, S. K.;
Watson, C.; Sanchez, L.; Lefort, J.; Osuna, P.; Gilbert, H. R.;
Nieves-Chinchilla, T.; Abbo, L.; Alexandrova, O.; Anastasiadis, A.;
Andretta, V.; Antonucci, E.; Appourchaux, T.; Aran, A.; Arge, C. N.;
Aulanier, G.; Baker, D.; Bale, S. D.; Battaglia, M.; Bellot Rubio,
L.; Bemporad, A.; Berthomier, M.; Bocchialini, K.; Bonnin, X.; Brun,
A. S.; Bruno, R.; Buchlin, E.; Büchner, J.; Bucik, R.; Carcaboso,
F.; Carr, R.; Carrasco-Blázquez, I.; Cecconi, B.; Cernuda Cangas, I.;
Chen, C. H. K.; Chitta, L. P.; Chust, T.; Dalmasse, K.; D'Amicis, R.;
Da Deppo, V.; De Marco, R.; Dolei, S.; Dolla, L.; Dudok de Wit, T.;
van Driel-Gesztelyi, L.; Eastwood, J. P.; Espinosa Lara, F.; Etesi,
L.; Fedorov, A.; Félix-Redondo, F.; Fineschi, S.; Fleck, B.; Fontaine,
D.; Fox, N. J.; Gandorfer, A.; Génot, V.; Georgoulis, M. K.; Gissot,
S.; Giunta, A.; Gizon, L.; Gómez-Herrero, R.; Gontikakis, C.; Graham,
G.; Green, L.; Grundy, T.; Haberreiter, M.; Harra, L. K.; Hassler,
D. M.; Hirzberger, J.; Ho, G. C.; Hurford, G.; Innes, D.; Issautier,
K.; James, A. W.; Janitzek, N.; Janvier, M.; Jeffrey, N.; Jenkins,
J.; Khotyaintsev, Y.; Klein, K. -L.; Kontar, E. P.; Kontogiannis,
I.; Krafft, C.; Krasnoselskikh, V.; Kretzschmar, M.; Labrosse, N.;
Lagg, A.; Landini, F.; Lavraud, B.; Leon, I.; Lepri, S. T.; Lewis,
G. R.; Liewer, P.; Linker, J.; Livi, S.; Long, D. M.; Louarn, P.;
Malandraki, O.; Maloney, S.; Martinez-Pillet, V.; Martinovic, M.;
Masson, A.; Matthews, S.; Matteini, L.; Meyer-Vernet, N.; Moraitis,
K.; Morton, R. J.; Musset, S.; Nicolaou, G.; Nindos, A.; O'Brien,
H.; Orozco Suarez, D.; Owens, M.; Pancrazzi, M.; Papaioannou, A.;
Parenti, S.; Pariat, E.; Patsourakos, S.; Perrone, D.; Peter, H.;
Pinto, R. F.; Plainaki, C.; Plettemeier, D.; Plunkett, S. P.; Raines,
J. M.; Raouafi, N.; Reid, H.; Retino, A.; Rezeau, L.; Rochus, P.;
Rodriguez, L.; Rodriguez-Garcia, L.; Roth, M.; Rouillard, A. P.;
Sahraoui, F.; Sasso, C.; Schou, J.; Schühle, U.; Sorriso-Valvo, L.;
Soucek, J.; Spadaro, D.; Stangalini, M.; Stansby, D.; Steller, M.;
Strugarek, A.; Štverák, Š.; Susino, R.; Telloni, D.; Terasa, C.;
Teriaca, L.; Toledo-Redondo, S.; del Toro Iniesta, J. C.; Tsiropoula,
G.; Tsounis, A.; Tziotziou, K.; Valentini, F.; Vaivads, A.; Vecchio,
A.; Velli, M.; Verbeeck, C.; Verdini, A.; Verscharen, D.; Vilmer, N.;
Vourlidas, A.; Wicks, R.; Wimmer-Schweingruber, R. F.; Wiegelmann,
T.; Young, P. R.; Zhukov, A. N.
2020A&A...642A...3Z Altcode: 2020arXiv200910772Z
Solar Orbiter is the first space mission observing the solar plasma
both in situ and remotely, from a close distance, in and out of the
ecliptic. The ultimate goal is to understand how the Sun produces
and controls the heliosphere, filling the Solar System and driving
the planetary environments. With six remote-sensing and four in-situ
instrument suites, the coordination and planning of the operations are
essential to address the following four top-level science questions:
(1) What drives the solar wind and where does the coronal magnetic field
originate?; (2) How do solar transients drive heliospheric variability?;
(3) How do solar eruptions produce energetic particle radiation that
fills the heliosphere?; (4) How does the solar dynamo work and drive
connections between the Sun and the heliosphere? Maximising the
mission's science return requires considering the characteristics
of each orbit, including the relative position of the spacecraft
to Earth (affecting downlink rates), trajectory events (such
as gravitational assist manoeuvres), and the phase of the solar
activity cycle. Furthermore, since each orbit's science telemetry
will be downloaded over the course of the following orbit, science
operations must be planned at mission level, rather than at the level
of individual orbits. It is important to explore the way in which those
science questions are translated into an actual plan of observations
that fits into the mission, thus ensuring that no opportunities are
missed. First, the overarching goals are broken down into specific,
answerable questions along with the required observations and the
so-called Science Activity Plan (SAP) is developed to achieve this. The
SAP groups objectives that require similar observations into Solar
Orbiter Observing Plans, resulting in a strategic, top-level view of
the optimal opportunities for science observations during the mission
lifetime. This allows for all four mission goals to be addressed. In
this paper, we introduce Solar Orbiter's SAP through a series of
examples and the strategy being followed.
---------------------------------------------------------
Title: The Solar Orbiter SPICE instrument. An extreme UV imaging
spectrometer
Authors: SPICE Consortium; Anderson, M.; Appourchaux, T.; Auchère, F.;
Aznar Cuadrado, R.; Barbay, J.; Baudin, F.; Beardsley, S.; Bocchialini,
K.; Borgo, B.; Bruzzi, D.; Buchlin, E.; Burton, G.; Büchel, V.;
Caldwell, M.; Caminade, S.; Carlsson, M.; Curdt, W.; Davenne, J.;
Davila, J.; Deforest, C. E.; Del Zanna, G.; Drummond, D.; Dubau,
J.; Dumesnil, C.; Dunn, G.; Eccleston, P.; Fludra, A.; Fredvik, T.;
Gabriel, A.; Giunta, A.; Gottwald, A.; Griffin, D.; Grundy, T.; Guest,
S.; Gyo, M.; Haberreiter, M.; Hansteen, V.; Harrison, R.; Hassler,
D. M.; Haugan, S. V. H.; Howe, C.; Janvier, M.; Klein, R.; Koller,
S.; Kucera, T. A.; Kouliche, D.; Marsch, E.; Marshall, A.; Marshall,
G.; Matthews, S. A.; McQuirk, C.; Meining, S.; Mercier, C.; Morris,
N.; Morse, T.; Munro, G.; Parenti, S.; Pastor-Santos, C.; Peter, H.;
Pfiffner, D.; Phelan, P.; Philippon, A.; Richards, A.; Rogers, K.;
Sawyer, C.; Schlatter, P.; Schmutz, W.; Schühle, U.; Shaughnessy,
B.; Sidher, S.; Solanki, S. K.; Speight, R.; Spescha, M.; Szwec, N.;
Tamiatto, C.; Teriaca, L.; Thompson, W.; Tosh, I.; Tustain, S.; Vial,
J. -C.; Walls, B.; Waltham, N.; Wimmer-Schweingruber, R.; Woodward,
S.; Young, P.; de Groof, A.; Pacros, A.; Williams, D.; Müller, D.
2020A&A...642A..14S Altcode: 2019arXiv190901183A; 2019arXiv190901183S
<BR /> Aims: The Spectral Imaging of the Coronal Environment (SPICE)
instrument is a high-resolution imaging spectrometer operating at
extreme ultraviolet wavelengths. In this paper, we present the concept,
design, and pre-launch performance of this facility instrument on the
ESA/NASA Solar Orbiter mission. <BR /> Methods: The goal of this paper
is to give prospective users a better understanding of the possible
types of observations, the data acquisition, and the sources that
contribute to the instrument's signal. <BR /> Results: The paper
discusses the science objectives, with a focus on the SPICE-specific
aspects, before presenting the instrument's design, including optical,
mechanical, thermal, and electronics aspects. This is followed by a
characterisation and calibration of the instrument's performance. The
paper concludes with descriptions of the operations concept and data
processing. <BR /> Conclusions: The performance measurements of the
various instrument parameters meet the requirements derived from the
mission's science objectives. The SPICE instrument is ready to perform
measurements that will provide vital contributions to the scientific
success of the Solar Orbiter mission.
---------------------------------------------------------
Title: Role of the Coronal Environment in the Formation of Four Shocks
Observed without Coronal Mass Ejections at Earth's Lagrangian Point L1
Authors: Pick, M.; Magdalenić, J.; Cornilleau-Wehrlin, N.; Grison,
B.; Schmieder, B.; Bocchialini, K.
2020ApJ...895..144P Altcode:
The main goal of this study is to determine the solar origin of four
single shocks observed at the Lagrange point L1 and followed by storm
sudden commencements (SSCs) during 2002. We look for associated coronal
mass ejections (CMEs), starting from estimates of the transit time from
Sun to Earth. For each CME, we investigate its association with a radio
type II burst, an indicator of the presence of a shock wave. For three
of the events, the type II burst is shown to propagate along the same,
or a similar, direction as the fastest segment of the CME leading
edge. We analyze for each event the role of the coronal environment
in the CME development, the shock formation, and their propagation,
to finally identify its complex evolution. The ballistic velocity
of these shocks during their propagation from the corona to L1 is
compared to the shock velocity at L1. Based on a detailed analysis of
the shock propagation and possible interactions up to 30 solar radii,
we find a coherent velocity evolution for each event, in particular
for one event, the 2002 April 14 SSC, for which a previous study did
not find a satisfactory CME source. For the other three events, we
observe the formation of a white-light shock overlying the different
sources associated with those events. The localization of the event
sources over the poles, together with an origin of the shocks being
due to encounters of CMEs, can explain why at L1 we observe only single
shocks and not interplanetary CMEs.
---------------------------------------------------------
Title: Low Geo-Effectiveness of Fast Halo CMEs Related to the 12
X-Class Flares in 2002
Authors: Schmieder, B.; Kim, R. -S.; Grison, B.; Bocchialini, K.;
Kwon, R. -Y.; Poedts, S.; Démoulin, P.
2020JGRA..12527529S Altcode: 2020arXiv200310777S
It is generally accepted that extreme space weather events tend to be
related to strong flares and fast halo coronal mass ejections (CMEs). In
the present paper, we carefully identify the chain of events from
the Sun to the Earth induced by all 12 X-class flares that occurred
in 2002. In this small sample, we find an unusual high rate (58%) of
solar sources with a longitude larger than 74°. Yet all 12 X-class
flares are associated with at least one CME. The fast halo CMEs (50%)
are related to interplanetary CMEs (ICMEs) at L1 and weak Dst minimum
values (more than -51 nT), while five (41%) of the 12 X-class flares
are related to solar proton events (SPEs). We conclude that (i) all
12 analyzed solar events, even those associated with fast halo CMEs
originating from the central disk region, and those ICMEs and SPEs
were not very geo-effective. This unexpected result demonstrates that
the suggested events in the chain (fast halo CME, X-class flares,
central disk region, ICME, and SPE) are not infallible proxies for
geo-effectiveness. (ii) The low value of integrated and normalized
southward component of the interplanetary magnetic field (Bz*) may
explain the low geo-effectiveness for this small sample. In fact,
Bz* is well correlated to the weak Dst and low auroral electrojet
activity. Hence, the only space weather impact at Earth in 2002 we
can explain is based on Bz* at L1.
---------------------------------------------------------
Title: Spectroscopic detection of coronal plasma flows in loops
undergoing thermal non-equilibrium cycles
Authors: Pelouze, Gabriel; Auchère, Frédéric; Bocchialini, Karine;
Froment, Clara; Parenti, Susanna; Soubrié, Elie
2020A&A...634A..54P Altcode: 2019arXiv191202538P
Context. Long-period intensity pulsations were recently detected in
the EUV emission of coronal loops and attributed to cycles of plasma
evaporation and condensation driven by thermal non-equilibrium
(TNE). Numerical simulations that reproduce this phenomenon
also predict the formation of periodic flows of plasma at coronal
temperatures along some of the pulsating loops. <BR /> Aims: We aim
to detect these predicted flows of coronal-temperature plasma in
pulsating loops. <BR /> Methods: We used time series of spatially
resolved spectra from the EUV imaging spectrometer (EIS) onboard
Hinode and tracked the evolution of the Doppler velocity in loops in
which intensity pulsations have previously been detected in images
of SDO/AIA. <BR /> Results: We measured signatures of flows that are
compatible with the simulations but only for a fraction of the observed
events. We demonstrate that this low detection rate can be explained
by line of sight ambiguities combined with instrumental limitations,
such as low signal-to-noise ratio or insufficient cadence. <P
/>Movies associated to Figs. 1, 4, 7, 10 are available at <A
href="https://www.aanda.org/10.1051/0004-6361/201935872/olm">https://www.aanda.org</A>
---------------------------------------------------------
Title: Comprehensive Determination of the Hinode/EIS Roll Angle
Authors: Pelouze, Gabriel; Auchère, Frédéric; Bocchialini, Karine;
Harra, Louise; Baker, Deborah; Warren, Harry P.; Brooks, David H.;
Mariska, John T.
2019SoPh..294...59P Altcode: 2019arXiv190311923P
We present a new coalignment method for the EUV Imaging Spectrometer
(EIS) on board the Hinode spacecraft. In addition to the pointing
offset and spacecraft jitter, this method determines the roll angle
of the instrument, which has never been systematically measured, and
which is therefore usually not corrected. The optimal pointing for EIS
is computed by maximizing the cross-correlations of the Fe XII 195.119
Å line with images from the 193 Å band of the Atmospheric Imaging
Assembly (AIA) on board the Solar Dynamics Observatory (SDO). By
coaligning 3336 rasters with high signal-to-noise ratio, we estimate
the rotation angle between EIS and AIA and explore the distribution
of its values. We report an average value of (−0.387<SUP>±0.007 )
∘</SUP>. We also provide a software implementation of this method
that can be used to coalign any EIS raster.
---------------------------------------------------------
Title: Geoeffectiveness of the 12 X-class flares in 2002
Authors: Schmieder, Brigitte; Kim, Rocksoon; Grison, Benjamin;
Bocchialini, Karine; Kwon, Young
2019EGUGA..21.1876S Altcode:
We analyze systematically the chain of events related to the 12
X-ray flares of X class occurring in 2002: source region, CME, ICME,
magnetic field at L1, geomagnetic indices, and SEP to determine if
we could explain their weak geo-effectiveness by usual criteria. No
intense geomagnetic storm is related to any of these flares. Only
one of them is associated with a moderate storm. The three others are
associated with a weak storm (-50 nT < min(Dst) < -30 nT). 75 %
of the flares are associated with a halo CME with a good correlation
rate for the speed/flux of the flare. The flare sources are mainly
close to the limb (70%). We conclude that the association of big
flares and strong geomagnetic disturbances may be valid only for
extreme or intense geomagnetic storms. Otherwise the magnetic energy
of active regions is released in an unexpected way into thermal energy
and kinetic energy or in ejections of energetic particles. The most
important parameter is the Bz value and its orientation. It seems that
the CMEs launched with high speed (around 2000 km/s) avoid the Earth
in our sample. The location of the solar source, the shape of the CME,
and the shock front have a direct impact on the geo-effectiveness.
---------------------------------------------------------
Title: Solar data, dataproducts, and tools at MEDOC
Authors: Buchlin, Eric; Caminade, Stéphane; Dufourg, Nicolas;
Auchère, Frédéric; Baudin, Frédéric; Bocchialini, Karine;
Boumier, Patrick; Janvier, Miho; Parenti, Susanna; Alingery, Pablo;
Ballans, Hervé; Chane-Yook, Martine; Dexet, Marc; Mercier, Claude;
Poulleau, Gilles
2019EGUGA..2117362B Altcode:
MEDOC (Multi-Experiment Data and Operation Centre), initially created
as a European data and operation centre for the SOHO mission, has
grown with data from other solar physics space missions, from STEREO
to SDO. Derived data products such as DEM maps from SDO/AIA, synoptic
EUV intensity maps from SOHO/EIT, and catalogues of solar structures
are also automatically produced and redistributed. Both the data and
the derived data products are publicly available from web interfaces
and from programmatic interfaces (with clients for IDL and Python),
allowing classical data analysis as well as automatic queries, data
download, and processing to be made on large datasets.
---------------------------------------------------------
Title: Erratum: Correction to: Statistical Analysis of Solar Events
Associated with Storm Sudden Commencements over One Year of Solar
Maximum During Cycle 23: Propagation from the Sun to the Earth
and Effects
Authors: Bocchialini, K.; Grison, B.; Menvielle, M.; Chambodut,
A.; Cornilleau-Wehrlin, N.; Fontaine, D.; Marchaudon, A.; Pick, M.;
Pitout, F.; Schmieder, B.; Régnier, S.; Zouganelis, I.
2019SoPh..294...38B Altcode:
Correction to: Solar Phys (2018)
293:75https://doi.org/10.1007/s11207-018-1278-5 <P />Please find in
this correction document the correct versions of abstract, Sect. 3.1
and Figs. 3 and 12.
---------------------------------------------------------
Title: The SDO AIA and HMI archive at MEDOC
Authors: Alingery, Pablo; Buchlin, Éric; Caminade, Stéphane; Ballans,
Hervé; Baudin, Frédéric; Parenti, Susanna; Bocchialini, Karine
2018csc..confE.113A Altcode:
MEDOC, created as the European data and operations center for SoHO,
hosts also data from STEREO, SDO, and various other solar physics
missions. The SDO archive at MEDOC represents more than 415TB of data,
and covers the full length of the mission. It includes aia.lev1 data at
a minimum cadence of 60s in the EUV channels (12s at specific periods of
interest), and most of the 720s-cadence HMI series. It is complemented
by a database of DEM maps derived from AIA. MEDOC provides a reliable,
convenient, and fast (especially for European users) access to these
SDO data, by a web interface and webservices. We also provide IDL
and Python clients to these webservices, allowing complex queries and
automated analyses on large datasets to be made.
---------------------------------------------------------
Title: Search for predicted periodic flows in loops undergoing
thermal non-equilibrium
Authors: Pelouze, Gabriel; Parenti, Susanna; Bocchialini, Karine;
Soubrie, Elie; Auchere, Frederic; Froment, Clara
2018cosp...42E2623P Altcode:
Long-period intensity pulsations have been recently detected in
coronal loopswith EUV images of both SoHO/EIT (Auchère et al.,
2014) and SDO/AIA (Froment etal., 2015). These pulsations have
been interpreted as resulting from thermalnon-equilibrium (TNE),
thus providing a signature of a highly-stratified andquasi-constant
heating at the loops footpoints (Froment et al., 2017; Auchèreet al.,
2016). Depending on the adequacy between the geometry of the loop
andthe characteristics of the heating, this can result in either
complete (atchromospheric temperatures) or incomplete (> 1 MK)
condensation and evaporationcycles, that are responsible for the
observed intensity pulsations. Using 1Dhydrodynamic simulations,
Froment et al. (2017) were able to reproduce theobserved pulsations,
with incomplete condensation for the active region studiedin their
previous paper. The simulations also predict periodic plasma flowsalong
the loops footpoints, with velocities up to 40 km/s. We try to detect
these flows by using time series of spatially resolved spectrafrom
the EUV spectrometer Hinode/EIS. We systematically search for EIS
datasetsthat correspond to the observation of pulsation events among
the 3000+ thatwere detected in AIA data, between 2010 and 2016. For the
9 datasets that arefound, we derive series of Doppler velocity maps,
which allows us to track theevolution of the plasma velocity in the
loop over several pulsation periods. Wethen compare these data to the
results of previous simulations andobservations. However the expected
pulsations in velocity cannot be identifiedin any of the datasets that
we analysed. We demonstrate that line of sightambiguities, combined
with low signal to noise ratio or lack of time cadence,can explain
this non-detection.
---------------------------------------------------------
Title: Statistical Analysis of Solar Events Associated with Storm
Sudden Commencements over One Year of Solar Maximum During Cycle 23:
Propagation from the Sun to the Earth and Effects
Authors: Bocchialini, K.; Grison, B.; Menvielle, M.; Chambodut,
A.; Cornilleau-Wehrlin, N.; Fontaine, D.; Marchaudon, A.; Pick, M.;
Pitout, F.; Schmieder, B.; Régnier, S.; Zouganelis, I.
2018SoPh..293...75B Altcode: 2018arXiv180307593B
Taking the 32 storm sudden commencements (SSCs) listed by the
International Service of Geomagnetic Indices (ISGI) of the Observatory
de l'Ebre during 2002 (solar activity maximum in Cycle 23) as a starting
point, we performed a multi-criterion analysis based on observations
(propagation time, velocity comparisons, sense of the magnetic
field rotation, radio waves) to associate them with solar sources,
identified their effects in the interplanetary medium, and looked at
the response of the terrestrial ionized and neutral environment. We
find that 28 SSCs can be related to 44 coronal mass ejections (CMEs),
15 with a unique CME and 13 with a series of multiple CMEs, among which
19 (68%) involved halo CMEs. Twelve of the 19 fastest CMEs with speeds
greater than 1000 km s<SUP>−1</SUP> are halo CMEs. For the 44 CMEs,
including 21 halo CMEs, the corresponding X-ray flare classes are: 3
X-class, 19 M-class, and 22 C-class flares. The probability for an SSC
to occur is 75% if the CME is a halo CME. Among the 500, or even more,
front-side, non-halo CMEs recorded in 2002, only 23 could be the source
of an SSC, i.e. 5%. The complex interactions between two (or more)
CMEs and the modification of their trajectories have been examined
using joint white-light and multiple-wavelength radio observations. The
detection of long-lasting type IV bursts observed at metric-hectometric
wavelengths is a very useful criterion for the CME-SSC events
association. The events associated with the most depressed Dst values
are also associated with type IV radio bursts. The four SSCs associated
with a single shock at L1 correspond to four radio events exhibiting
characteristics different from type IV radio bursts. The solar-wind
structures at L1 after the 32 SSCs are 12 magnetic clouds (MCs), 6
interplanetary coronal mass ejections (ICMEs) without an MC structure,
4 miscellaneous structures, which cannot unambiguously be classified
as ICMEs, 5 corotating or stream interaction regions (CIRs/SIRs), one
CIR caused two SSCs, and 4 shock events; note than one CIR caused two
SSCs. The 11 MCs listed in 3 or more MC catalogs covering the year 2002
are associated with SSCs. For the three most intense geomagnetic storms
(based on Dst minima) related to MCs, we note two sudden increases
of the Dst, at the arrival of the sheath and the arrival of the MC
itself. In terms of geoeffectiveness, the relation between the CME
speed and the magnetic-storm intensity, as characterized using the Dst
magnetic index, is very complex, but generally CMEs with velocities at
the Sun larger than 1000 km s<SUP>−1</SUP> have larger probabilities
to trigger moderate or intense storms. The most geoeffective events are
MCs, since 92% of them trigger moderate or intense storms, followed
by ICMEs (33%). At best, CIRs/SIRs only cause weak storms. We show
that these geoeffective events (ICMEs or MCs) trigger an increased and
combined auroral kilometric radiation (AKR) and non-thermal continuum
(NTC) wave activity in the magnetosphere, an enhanced convection in
the ionosphere, and a stronger response in the thermosphere. However,
this trend does not appear clearly in the coupling functions, which
exhibit relatively weak correlations between the solar-wind energy
input and the amplitude of various geomagnetic indices, whereas the
role of the southward component of the solar-wind magnetic field is
confirmed. Some saturation appears for Dst values <−100 nT on
the integrated values of the polar and auroral indices.
---------------------------------------------------------
Title: On the Occurrence of Thermal Nonequilibrium in Coronal Loops
Authors: Froment, C.; Auchère, F.; Mikić, Z.; Aulanier, G.;
Bocchialini, K.; Buchlin, E.; Solomon, J.; Soubrié, E.
2018ApJ...855...52F Altcode: 2018arXiv180204010F
Long-period EUV pulsations, recently discovered to be common in active
regions, are understood to be the coronal manifestation of thermal
nonequilibrium (TNE). The active regions previously studied with
EIT/Solar and Heliospheric Observatory and AIA/SDO indicated that
long-period intensity pulsations are localized in only one or two
loop bundles. The basic idea of this study is to understand why. For
this purpose, we tested the response of different loop systems, using
different magnetic configurations, to different stratifications and
strengths of the heating. We present an extensive parameter-space study
using 1D hydrodynamic simulations (1020 in total) and conclude that the
occurrence of TNE requires specific combinations of parameters. Our
study shows that the TNE cycles are confined to specific ranges in
parameter space. This naturally explains why only some loops undergo
constant periodic pulsations over several days: since the loop geometry
and the heating properties generally vary from one loop to another in
an active region, only the ones in which these parameters are compatible
exhibit TNE cycles. Furthermore, these parameters (heating and geometry)
are likely to vary significantly over the duration of a cycle, which
potentially limits the possibilities of periodic behavior. This study
also confirms that long-period intensity pulsations and coronal rain are
two aspects of the same phenomenon: both phenomena can occur for similar
heating conditions and can appear simultaneously in the simulations.
---------------------------------------------------------
Title: Statistical analysis of solar events associated with SSC over
year of solar maximum during cycle 23: 2. Characterisation on the
Sun-Earth path - Geoeffectiveness
Authors: Cornilleau-Wehrlin, N.; Bocchialini, K.; Menvielle, M.;
Fontaine, D.; Grison, B.; Marchaudon, A.; Pick, M.; Pitout, F.;
Schmieder, B.; Regnier, S.; Zouganelis, Y.; Chambodut, A.
2017AGUFMSH31A2712C Altcode:
Taking the 32 sudden storm commencements (SSC) listed by the observatory
de l'Ebre / ISGI over the year 2002 (maximal solar activity) as a
starting point, we performed a statistical analysis of the related
solar sources, solar wind signatures, and terrestrial responses. For
each event, we characterized and identified, as far as possible, (i)
the sources on the Sun (Coronal Mass Ejections -CME-), with the help
of a series of criteria (velocities, drag coefficient, radio waves,
magnetic field polarity), as well as (ii) the structure and properties
in the interplanetary medium, at L1, of the event associated to the SSC:
magnetic clouds -MC-, non-MC interplanetary coronal mass ejections
-ICME-, co-rotating/stream interaction regions -SIR/CIR-, shocks
only and unclear events that we call "miscellaneous" events. The
geoeffectiveness of the events, classified by category at L1, is
analysed by their signatures in the Earth ionized (magnetosphere
and ionosphere) and neutral (thermosphere) environments, using a
broad set of in situ, remote and ground based instrumentation. The
role of the presence of a unique or of a multiple source at the Sun,
of its nature, halo or non halo CME, is also discussed. The set of
observations is statistically analyzed so as to evaluate and compare
the geoeffectiveness of the events. The results obtained for this
set of geomagnetic storms started by SSCs is compared to the overall
statistics of year 2002, relying on already published catalogues of
events, allowing assessing the relevance of our approach ; for instance
all the 12 well identified Magnetic Clouds of 2002 give rise to SSCs.
---------------------------------------------------------
Title: Statistical Analysis of Solar Events Associated with Storm
Sudden Commencements over One Year of Solar Maximum during Cycle 23:
Propagation and Effects from the Sun to the Earth.
Authors: Bocchialini, K.; Grison, B.; Menvielle, M.; Chambodut,
A.; Cornilleau-Wehrlin, N.; Fontaine, D.; Marchaudon, A.; Pick, M.;
Pitout, F.; Schmieder, B.; Régnier, S.; Zouganelis, I.
2017sf2a.conf..181B Altcode:
From the list of 32 SSCs over the year 2002, we performed a
multi-criteria analysis based on propagation time, velocity comparison,
sense of the magnetic field rotation, radio waves to associate them
with solar sources, identify their causes in the interplanetary medium
and then look at the response of the terrestrial ionized and neutral
environment to them. The complex interactions between two (or more) CMEs
and the modification in their trajectory have been examined using joint
white light and multiple-wavelength radio observations. The structures
at L_1 after the 32 SSCs are regarded as Magnetic Clouds (MCs),
ICMEs without a MC structure, Miscellaneous structures, CIRs/SIRs,
and shock-only events. In terms of geoeffectivity, generally CMEs with
velocities at the Sun larger than 1000 km.s-1 have larger probabilities
to trigger moderate or intense storms. The most geoeffective events
are MCs, since 92% of them trigger moderate or intense storms. The
geoeffective events trigger an increased and combined AKR and NTC wave
activity in the magnetosphere, an enhanced convection in the ionosphere
and a stronger response in the thermosphere.
---------------------------------------------------------
Title: Statistical Analysis of Solar Events Associated with SSC over
Year of Solar Maximum during Cycle 23: 1. Identification of Related
Sun-Earth Events
Authors: Grison, B.; Bocchialini, K.; Menvielle, M.; Chambodut,
A.; Cornilleau-Wehrlin, N.; Fontaine, D.; Marchaudon, A.; Pick, M.;
Pitout, F.; Schmieder, B.; Regnier, S.; Zouganelis, Y.
2017AGUFMSH31A2711G Altcode:
Taking the 32 sudden storm commencements (SSC) listed by the observatory
de l'Ebre / ISGI over the year 2002 (maximal solar activity) as a
starting point, we performed a statistical analysis of the related
solar sources, solar wind signatures, and terrestrial responses. For
each event, we characterized and identified, as far as possible,
(i) the sources on the Sun (Coronal Mass Ejections -CME-), with the
help of a series of herafter detailed criteria (velocities, drag
coefficient, radio waves, polarity), as well as (ii) the structure
and properties in the interplanetary medium, at L1, of the event
associated to the SSC: magnetic clouds -MC-, non-MC interplanetary
coronal mass ejections -ICME-, co-rotating/stream interaction regions
-SIR/CIR-, shocks only and unclear events that we call "miscellaneous"
events. The categorization of the events at L1 is made on published
catalogues. For each potential CME/L1 event association we compare
the velocity observed at L1 with the one observed at the Sun and the
estimated balistic velocity. Observations of radio emissions (Type II,
Type IV detected from the ground and /or by WIND) associated to the CMEs
make the solar source more probable. We also compare the polarity of
the magnetic clouds with the hemisphere of the solar source. The drag
coefficient (estimated with the drag-based model) is calculated for
each potential association and it is compared to the expected range
values. We identified a solar source for 26 SSC related events. 12
of these 26 associations match all criteria. We finally discuss the
difficulty to perform such associations.
---------------------------------------------------------
Title: Erratum: “On the Fourier and Wavelet Analysis of Coronal Time
Series” (<A href="https://doi.org/10.3847/0004-637x/825/2/110">2016,
ApJ, 825, 110</A>)
Authors: Auchère, F.; Froment, C.; Bocchialini, K.; Buchlin, E.;
Solomon, J.
2017ApJ...838..166A Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Statistical analysis of solar events associated with SSC over
one year of solar maximum during cycle 23: propagation and effects
from the Sun to the Earth
Authors: Cornilleau-Wehrlin, Nicole; Bocchialini, Karine; Menvielle,
Michel; Chambodut, Aude; Fontaine, Dominique; Grison, Benjamin;
Marchaudon, Aurélie; Pick, Monique; Pitout, Frédéric; Schmieder,
Brigitte; Régnier, Stéphane; Zouganelis, Yannis
2017EGUGA..19.3689C Altcode:
Taking the 32 sudden storm commencements (SSC) listed by the observatory
de l'Ebre / ISGI over the year 2002 (maximal solar activity) as a
starting point, we performed a statistical analysis of the related
solar sources, solar wind signatures, and terrestrial responses. For
each event, we characterized and identified, as far as possible,
(i) the sources on the Sun (Coronal Mass Ejections -CME-), with the
help of a series of criteria (velocities, drag coefficient, radio
waves, helicity), as well as (ii) the structure and properties in the
interplanetary medium, at L1, of the event associated to the SSC:
magnetic clouds -MC-, non-MC interplanetary coronal mass ejections
-ICME-, co-rotating/stream interaction regions -SIR/CIR-, shocks only
and unclear events that we call "miscellaneous" events. The observed
Sun-to-Earth travel times are compared to those estimated using existing
simple models of propagation in the interplanetary medium. This
comparison is used to statistically assess performances of various
models. The geoeffectiveness of the events, classified by category at
L1, is analysed by their signatures in the Earth ionized (magnetosphere
and ionosphere) and neutral (thermosphere) environments, using a
broad set of in situ, remote and ground based instrumentation. The
role of the presence of a unique or of a multiple source at the Sun,
of its nature, halo or non halo CME, is also discussed. The set of
observations is statistically analyzed so as to evaluate and compare
the geoeffectiveness of the events. The results obtained for this
set of geomagnetic storms started by SSCs is compared to the overall
statistics of year 2002, relying on already published catalogues of
events, allowing assessing the relevance of our approach (for instance
the all 12 well identified Magnetic Clouds of 2002 give rise to SSCs).
---------------------------------------------------------
Title: Long-period Intensity Pulsations in Coronal Loops Explained
by Thermal Non-equilibrium Cycles
Authors: Froment, C.; Auchère, F.; Aulanier, G.; Mikić, Z.;
Bocchialini, K.; Buchlin, E.; Solomon, J.
2017ApJ...835..272F Altcode: 2017arXiv170101309F
In solar coronal loops, thermal non-equilibrium (TNE) is a phenomenon
that can occur when the heating is both highly stratified and
quasi-constant. Unambiguous observational identification of TNE
would thus permit us to strongly constrain heating scenarios. While
TNE is currently the standard interpretation of coronal rain, the
long-term periodic evolution predicted by simulations has never been
observed. However, the detection of long-period intensity pulsations
(periods of several hours) has been recently reported with the Solar
and Heliospheric Observatory/EIT, and this phenomenon appears to be very
common in loops. Moreover, the three intensity-pulsation events that we
recently studied with the Solar Dynamics Observatory/Atmospheric Imaging
Assembly (AIA) show strong evidence for TNE in warm loops. In this
paper, a realistic loop geometry from linear force-free field (LFFF)
extrapolations is used as input to 1D hydrodynamic simulations. Our
simulations show that, for the present loop geometry, the heating has
to be asymmetrical to produce TNE. We analyze in detail one particular
simulation that reproduces the average thermal behavior of one of the
pulsating loop bundle observed with AIA. We compare the properties of
this simulation with those deduced from the observations. The magnetic
topology of the LFFF extrapolations points to the presence of sites
of preferred reconnection at one footpoint, supporting the presence
of asymmetric heating. In addition, we can reproduce the temporal
large-scale intensity properties of the pulsating loops. This simulation
further strengthens the interpretation of the observed pulsations as
signatures of TNE. This consequently provides important information
on the heating localization and timescale for these loops.
---------------------------------------------------------
Title: Thermal Non-Equilibrium Revealed by Periodic Pulses of Random
Amplitudes in Solar Coronal Loops
Authors: Auchère, F.; Froment, C.; Bocchialini, K.; Buchlin, E.;
Solomon, J.
2016usc..confE.131A Altcode:
We recently detected variations in extreme ultraviolet intensity in
coronal loops repeating with periods of several hours. Models of loops
including stratified and quasi-steady heating predict the development
of a state of thermal non-equilibrium (TNE): cycles of evaporative
upflows at the footpoints followed by falling condensations at the
apex. Based on Fourier and wavelet analysis, we demonstrate that the
observed periodic signals are indeed not signatures of vibrational
modes. Instead, superimposed on the power law expected from the
stochastic background emission, the power spectra of the time series
exhibit the discrete harmonics and continua expected from periodic
trains of pulses of random amplitudes. These characteristics reinforce
our earlier interpretation of these pulsations as being aborted
TNE cycles.
---------------------------------------------------------
Title: Fourier and Wavelet Analysis of Coronal Time Series
Authors: Auchère, F.; Froment, C.; Bocchialini, K.; Buchlin, E.;
Solomon, J.
2016usc..confE.130A Altcode:
Using Fourier and wavelet analysis, we critically re-assess the
significance of our detection of periodic pulsations in coronal
loops. We show that the proper identification of the frequency
dependence and statistical properties of the different components of
the power spectra provies a strong argument against the common practice
of data detrending, which tends to produce spurious detections around
the cut-off frequency of the filter. In addition, the white and red
noise models built into the widely used wavelet code of Torrence &
Compo cannot, in most cases, adequately represent the power spectra of
coronal time series, thus also possibly causing false positives. Both
effects suggest that several reports of periodic phenomena should
be re-examined. The Torrence & Compo code nonetheless effectively
computes rigorous confidence levels if provided with pertinent models of
mean power spectra, and we describe the appropriate manner in which to
call its core routines. We recall the meaning of the default confidence
levels output from the code, and we propose new Monte-Carlo-derived
levels that take into account the total number of degrees of freedom
in the wavelet spectra. These improvements allow us to confirm that
the power peaks that we detected have a very low probability of being
caused by noise.
---------------------------------------------------------
Title: Long-period Intensity Pulsations as the Manifestation of the
Heating Stratification and Timescale in Coronal Loops
Authors: Froment, Clara; Auchère, Frédéric; Aulanier, Guillaume;
Mikić, Zoran; Bocchialini, Karine; Buchlin, Eric; Solomon, Jacques
2016usc..confE..47F Altcode:
In solar coronal loops, thermal non-equilibrium (TNE) is a phenomenon
that can occur when the heating is both highly-stratified and
quasi-constant. Unambiguous observational identification of TNE
would thus permit to strongly constrain heating scenarios. Up to
now, while TNE is the standard interpretation of coronal rain, it
was not believed to happen commonly in warm coronal loops. Recently,
the detection of long-period intensity pulsations (periods of several
hours) has been reported with SoHO/EIT. This phenomenon appears to be
very common in loops (Auchère et al. 2014). In Froment et al. 2015,
three intensity-pulsation events studied with SDO/AIA, show strong
evidence for TNE in warm loops. We use realistic loop geometries
from LFFF extrapolations for one of these events are used as input
to a 1D hydrodynamic simulation of TNE. A highly-stratified heating
function is chosen to reproduce the observed period of pulsation and
temperature of the loops. With these conditions, the heating function
has to be asymmetric. The magnetic topology of the LFFF extrapolations
points to the presence of sites of preferred reconnection at one
footpoint, supporting the presence of asymmetric heating. We compared
the properties of the simulated loop with the properties deduced
from observations. We found that the 1D hydrodynamic simulation
can reproduce the large temporal scale intensity properties of the
pulsating loops (Froment et al. 2016, submitted). This simulation
further strengthen the interpretation of the observed pulsations as
signatures of TNE. This implies that the heating for these loops is
highly-stratified and that the frequency of the heating events must
be high compared to the typical cooling time.
---------------------------------------------------------
Title: Thermal Non-equilibrium Revealed by Periodic Pulses of Random
Amplitudes in Solar Coronal Loops
Authors: Auchère, F.; Froment, C.; Bocchialini, K.; Buchlin, E.;
Solomon, J.
2016ApJ...827..152A Altcode: 2016arXiv160803789A
We recently detected variations in extreme ultraviolet intensity in
coronal loops repeating with periods of several hours. Models of loops
including stratified and quasi-steady heating predict the development
of a state of thermal non-equilibrium (TNE): cycles of evaporative
upflows at the footpoints followed by falling condensations at the
apex. Based on Fourier and wavelet analysis, we demonstrate that the
observed periodic signals are indeed not signatures of vibrational
modes. Instead, superimposed on the power law expected from the
stochastic background emission, the power spectra of the time series
exhibit the discrete harmonics and continua expected from periodic
trains of pulses of random amplitudes. These characteristics reinforce
our earlier interpretation of these pulsations as being aborted
TNE cycles.
---------------------------------------------------------
Title: Solar abundances with the SPICE spectral imager on Solar
Orbiter
Authors: Giunta, Alessandra; Haberreiter, Margit; Peter, Hardi;
Vial, Jean-Claude; Harrison, Richard; Parenti, Susanna; Innes, Davina;
Schmutz, Werner; Buchlin, Eric; Chamberlin, Phillip; Thompson, William;
Bocchialini, Karine; Gabriel, Alan; Morris, Nigel; Caldwell, Martin;
Auchere, Frederic; Curdt, Werner; Teriaca, Luca; Hassler, Donald M.;
DeForest, Craig; Hansteen, Viggo; Carlsson, Mats; Philippon, Anne;
Janvier, Miho; Wimmer-Schweingruber, Robert; Griffin, Douglas; Baudin,
Frederic; Davila, Joseph; Fludra, Andrzej; Waltham, Nick; Eccleston,
Paul; Gottwald, Alexander; Klein, Roman; Hanley, John; Walls, Buddy;
Howe, Chris; Schuehle, Udo; Gyo, Manfred; Pfiffner, Dany
2016cosp...41E.681G Altcode:
Elemental composition of the solar atmosphere and in particular
abundance bias of low and high First Ionization Potential (FIP)
elements are a key tracer of the source regions of the solar wind. These
abundances and their spatio-temporal variations, as well as the other
plasma parameters , will be derived by the SPICE (Spectral Imaging
of the Coronal Environment) EUV spectral imager on the upcoming
Solar Orbiter mission. SPICE is designed to provide spectroheliograms
(spectral images) using a core set of emission lines arising from ions
of both low-FIP and high-FIP elements. These lines are formed over
a wide range of temperatures, enabling the analysis of the different
layers of the solar atmosphere. SPICE will use these spectroheliograms
to produce dynamic composition maps of the solar atmosphere to be
compared to in-situ measurements of the solar wind composition of
the same elements (i.e. O, Ne, Mg, Fe). This will provide a tool to
study the connectivity between the spacecraft (the Heliosphere) and
the Sun. We will discuss the SPICE capabilities for such composition
measurements.
---------------------------------------------------------
Title: On the Fourier and Wavelet Analysis of Coronal Time Series
Authors: Auchère, F.; Froment, C.; Bocchialini, K.; Buchlin, E.;
Solomon, J.
2016ApJ...825..110A Altcode: 2016arXiv160605251A
Using Fourier and wavelet analysis, we critically re-assess the
significance of our detection of periodic pulsations in coronal
loops. We show that the proper identification of the frequency
dependence and statistical properties of the different components of the
power spectra provides a strong argument against the common practice
of data detrending, which tends to produce spurious detections around
the cut-off frequency of the filter. In addition, the white and red
noise models built into the widely used wavelet code of Torrence &
Compo cannot, in most cases, adequately represent the power spectra of
coronal time series, thus also possibly causing false positives. Both
effects suggest that several reports of periodic phenomena should
be re-examined. The Torrence & Compo code nonetheless effectively
computes rigorous confidence levels if provided with pertinent models of
mean power spectra, and we describe the appropriate manner in which to
call its core routines. We recall the meaning of the default confidence
levels output from the code, and we propose new Monte-Carlo-derived
levels that take into account the total number of degrees of freedom
in the wavelet spectra. These improvements allow us to confirm that
the power peaks that we detected have a very low probability of being
caused by noise.
---------------------------------------------------------
Title: Statistical analysis of CMEs' geoeffectiveness over one year
of solar maximum during cycle 23
Authors: Schmieder, Brigitte; Bocchialini, Karine; Menvielle, Michel
2016cosp...41E1751S Altcode:
Using different propagation models from the Sun to the Earth,
we performed a statistical analysis over the year 2002 on CME's
geoeffectiveness linked to sudden storm commencements (ssc). We
also classified the perturbations of the interplanetary medium that
trigger the sscs. For each CME, the sources on the Sun of the CME are
identified as well as the properties of the parameters deduced from
spacecraft measurements along the path of the CME related event,
in the solar atmosphere, the interplanetary medium, and the Earth
ionized (magnetosphere and ionosphere) and neutral (thermosphere)
environments. The set of observations is statistically analysed so
as to evaluate the geoeffectiveness of CMEs in terms of ionospheric
and thermospheric signatures, with attention to possible differences
related to different kinds of solar sources. The observed Sun-to-Earth
travel times are compared to those estimated using the existing models
of propagation in the interplanetary medium, and this comparison is
used to statistically assess the performances of the various models.
---------------------------------------------------------
Title: Evidence for Evaporation-incomplete Condensation Cycles in
Warm Solar Coronal Loops
Authors: Froment, C.; Auchère, F.; Bocchialini, K.; Buchlin, E.;
Guennou, C.; Solomon, J.
2015ApJ...807..158F Altcode: 2015arXiv150408129F
Quasi-constant heating at the footpoints of loops leads to evaporation
and condensation cycles of the plasma: thermal non-equilibrium
(TNE). This phenomenon is believed to play a role in the formation
of prominences and coronal rain. However, it is often discounted
as being involved in the heating of warm loops because the
models do not reproduce observations. Recent simulations have
shown that these inconsistencies with observations may be due to
oversimplifications of the geometries of the models. In addition,
our recent observations reveal that long-period intensity pulsations
(several hours) are common in solar coronal loops. These periods are
consistent with those expected from TNE. The aim of this paper is to
derive characteristic physical properties of the plasma for some of
these events to test the potential role of TNE in loop heating. We
analyzed three events in detail using the six EUV coronal channels
of the Solar Dynamics Observatory/Atmospheric Imaging Assembly. We
performed both a differential emission measure (DEM) and a time-lag
analysis, including a new method to isolate the relevant signal from
the foreground and background emission. For the three events, the DEM
undergoes long-period pulsations, which is a signature of periodic
heating even though the loops are captured in their cooling phase,
as is the bulk of the active regions. We link long-period intensity
pulsations to new signatures of loop heating with strong evidence for
evaporation and condensation cycles. We thus simultaneously witness
widespread cooling and TNE. Finally, we discuss the implications of
our new observations for both static and impulsive heating models.
---------------------------------------------------------
Title: The SUMER Data in the SOHO Archive
Authors: Curdt, W.; Germerott, D.; Wilhelm, K.; Schühle, U.; Teriaca,
L.; Innes, D.; Bocchialini, K.; Lemaire, P.
2014SoPh..289.2345C Altcode: 2013arXiv1309.1314C
We have released an archive of all observational data of the VUV
spectrometer Solar Ultraviolet Measurements of Emitted Radiation
(SUMER) on SOHO that have been acquired until now. The operational
phase started with `first light' observations on 27 January 1996 and
will end in 2014. Future data will be added to the archive when they
become available. The archive consists of a set of raw data (Level
0) and a set of data that are processed and calibrated to the best
knowledge we have today (Level 1). This communication describes step
by step the data acquisition and processing that has been applied in an
automated manner to build the archive. It summarizes the expertise and
insights into the scientific use of SUMER spectra that has accumulated
over the years. It also indicates possibilities for further enhancement
of the data quality. With this article we intend to convey our own
understanding of the instrument performance to the scientific community
and to introduce the new, standard FITS-format database.
---------------------------------------------------------
Title: Long-period intensity pulsations in the solar corona during
activity cycle 23
Authors: Auchère, F.; Bocchialini, K.; Solomon, J.; Tison, E.
2014A&A...563A...8A Altcode: 2013arXiv1312.3792A
We report on the detection (10σ) of 917 events of long-period (3 to
16 h) intensity pulsations in the 19.5 nm passband of the SOHO Extreme
ultraviolet Imaging Telescope. The data set spans from January 1997
to July 2010, i.e. the entire solar cycle 23 and the beginning of
cycle 24. The events can last for up to six days and have relative
amplitudes up to 100%. About half of the events (54%) are found
to happen in active regions, and 50% of these have been visually
associated with coronal loops. The remaining 46% are localized in
the quiet Sun. We performed a comprehensive analysis of the possible
instrumental artefacts and we conclude that the observed signal is
of solar origin. We discuss several scenarios that could explain the
main characteristics of the active region events. The long periods
and the amplitudes observed rule out any explanation in terms of
magnetohydrodynamic waves. Thermal non-equilibrium could produce the
right periods, but it fails to explain all the observed properties
of coronal loops and the spatial coherence of the events. We propose
that moderate temporal variations of the heating term in the energy
equation, so as to avoid a thermal non-equilibrium state, could be
sufficient to explain those long-period intensity pulsations. The
large number of detections suggests that these pulsations are common
in active regions. This would imply that the measurement of their
properties could provide new constraints on the heating mechanisms
of coronal loops. <P />Movies are available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201322572/olm">http://www.aanda.org</A>
---------------------------------------------------------
Title: Observations and possible interpretations of very long period
intensity pulsations in solar coronal loops
Authors: Froment, Clara; Solomon, Jacques; Buchlin, Eric; Bocchialini,
Karine; Auchere, Frederic; Guennou, Chloe
2014cosp...40E.903F Altcode:
We discovered that intensity pulsations with periods ranging from 3
to 16 hours are common in solar coronal loops. Initially developed
for EIT/SOHO 195 nm images, the automatic detection algorithm is now
running on AIA/SDO data and allows detection of pulsation events in
six coronal bands simultaneously. From may 2010 to december 2013, we
detected more than 2000 events in the 6 EUV bands. We focus our study
on pulsations in active regions and in particular in solar coronal
loops where most of events are detected. A multi-wavelength analysis
of some characteristic events is presented to help understand their
physical nature. We perform a Differential Emission Measure analysis
on AIA time series in order to determine the temporal variations of the
thermal structure of the pulsating loops. This analysis gives important
clues to investigate possible physical interpretations in particular in
term of small perturbations of loops in static equilibrium and to study
how this can constraint coronal heating models. We will also compare
our observations to the results of a MHD turbulence and heating model
of coronal loops.
---------------------------------------------------------
Title: Can the Differential Emission Measure Constrain the Timescale
of Energy Deposition in the Corona?
Authors: Guennou, C.; Auchère, F.; Klimchuk, J. A.; Bocchialini,
K.; Parenti, S.
2013ApJ...774...31G Altcode: 2013arXiv1306.3114G
In this paper, the ability of the Hinode/EIS instrument to detect
radiative signatures of coronal heating is investigated. Recent
observational studies of active region cores suggest that both
the low and high frequency heating mechanisms are consistent with
observations. Distinguishing between these possibilities is important
for identifying the physical mechanism(s) of the heating. The
differential emission measure (DEM) tool is one diagnostic that
allows us to make this distinction, through the amplitude of the
DEM slope coolward of the coronal peak. It is therefore crucial to
understand the uncertainties associated with these measurements. Using
proper estimations of the uncertainties involved in the problem
of DEM inversion, we derive confidence levels on the observed DEM
slope. Results show that the uncertainty in the slope reconstruction
strongly depends on the number of lines constraining the slope. Typical
uncertainty is estimated to be about ±1.0 in the more favorable cases.
---------------------------------------------------------
Title: Tomographic reconstructions of large scale coronal structures
Authors: Guennou, C.; Auchère, F.; Seaton, D.; Canou, A.; Barbey,
N.; Bocchialini, K.
2013enss.confE..83G Altcode:
Classical plasma diagnostic techniques suffer from the line of sight
(LOS) integration problem, which can confuse structures to the point
that measurements crucial to the understanding of coronal physics are
difficult to interpret. Tomography provides one way of understanding the
LOS content, giving important insights on the morphology and physical
properties of the coronal structures. Large scale, long-lived, arch-like
structures are observed in the field of view of EUV telescopes at
mid-latitudes, most notably in the 174 nm passband. In the present work,
we use tomographic inversions of the solar corona the 3D morphology of
these structures. We focus on a 28 days period of data from July/August
2012 during which some of these features were observed up to 1.7 Rsol by
the SWAP/PROBA2 telescope. Additional multi-wavelength observations in
the 6 bands of AIA/SDO are used to derive the corresponding 3-D maps
of electron density and temperature. The results are then compared
with global magnetic field extrapolations. We conclude by proposing
an interpretation of the morphology of these structures as seen in
EUV images.
---------------------------------------------------------
Title: GAIA-DEM : The Gaussian AIA DEm Maps database
Authors: Guennou, C.; Auchère, F.; Soubrié, E.; Bocchialini, K.
2013enss.confE...7G Altcode:
Providing the amount of emitting material as a function of the
temperature along the line-of-sight, the Differential Emisssion Measure
(DEM) analysis is a widespread diagnostic tool, used for most types of
coronal structures. With six available coronal bands, the AIA instrument
on board the SDO satellite provides new possibilities to more reliably
estimate the DEM than previous UV imagers, and over a large FOV. The
purpose of this database is to provide synoptic Gaussian DEM inversions
of the AIA data. Using our recent results (Guennou et al. 2012a and
2012b), these maps can be then interpreted, taking advantage of our new
tools developed to facilitate the DEM interpretation. The GAIA database
provides the best Gaussian DEM fit matching the observations. A Gaussian
form is a good first order approximation to determine the main thermal
characteristics of the coronal plasma. With generally four inversions
per day, at a 6 hours cadence, this database enables the user to
quickly examine the global evolution of the thermal structure of the
solar corona. DEM maps are available at http://medoc-dem.ias.u-psud.fr/.
---------------------------------------------------------
Title: Can the Differential Emission Measure diagnostic be used to
constrain the timescale of energy deposition in the corona?
Authors: Guennou, C.; Auchère, F.; Klimchuk, J. A.; Bocchialini,
K.; Parenti, S.
2013enss.confE..34G Altcode:
Differential emission measure (DEM) analysis is a widespread tool used
to diagnose the thermal properties of coronal plasmas. The slope of
the DEM distribution coolward of the coronal peak (near 3-4MK in active
regions) can be used to diagnose the timescale for the energy deposition
repeating on a given magnetic strand. Recent AR studies suggest that
some active region cores are consistent with low frequency heating
mechanisms, where the plasma cools completely before being reheated,
while other show consistency with high frequency energy deposition,
where rapid reheating causes the temperature to fluctuate about
a particular value. Distinguishing between these possibilities is
important for identifying the physical mechanism of the heating. It is
therefore crucial to understand the uncertainties in measurements of
observed DEM slopes. In this work, based on a probabilistic approach
and Monte Carlo simulations, we carefully assess the errors in the
slopes determined from EIS data. We consider both the random errors due
to photon counting statistics, and the systematic errors associated
with uncertainties in atomic physics and instrument calibration. The
technique developed provides all the solutions consistent with the data
and their associated probabilities. We demonstrate how the quality
and the accuracy of the inversion are affected by the presence of
noises and systematic errors, and we characterise the quality of the
DEM inversion and its statistical properties. From these results,
estimation of the uncertainties in the reconstructed slopes can be
derived, thereby allowing a proper interpretation of the degree of
agreement between observations and heating model predictions.
---------------------------------------------------------
Title: MEDIA : MEDoc Interface for AIA
Authors: Alingery, P.; Soubrié, E.; Auchère, F.; Bocchialini, K.;
Boignard, J. P.; Buchlin, E.; Malappert, J. C.; Parenti, S.
2013enss.confE..88A Altcode:
MEDOC, the space solar data center at Orsay
(http://www.ias.u-psud.fr/medoc) is now providing a new web access
to the AIA/SDO level 1 images. This interface has the advantage of
being simple, intuitive, very stable and fast. The full resolution
4k x 4k AIA level 1 images archived at MEDOC are downloaded from
upstream DRMS nodes with a 1 minute cadence at all wavelengths. The
dataset will be kept online on a redundant archive for the whole SDO
mission duration. The FITS files are accessible via an user friendly
web interface (http://medoc-sdo.ias.u-psud.fr) that allows users
to request data by selecting a date range, the desired wavelengths
and a sampling rate (choosing a cadence from 1 minute to 1 day). For
each file, users can preview the image (using the Helioviewer tool)
or display the header information before downloading the FITS files
(with or without Rice-compression). This web interface was built
using Sitools2, a tool developed by CNES, the French space agency, and
supports most browsers. For more advanced users, a Search/Get Python
module is also available at http://sdo.ias.u-psud.fr/python. The users
can use it to build more complex yet more powerful queries. We encourage
everyone in Europe and beyond to use these new services!
---------------------------------------------------------
Title: On the Accuracy of the Differential Emission Measure
Diagnostics of Solar Plasmas. Application to SDO/AIA. II. Multithermal
Plasmas
Authors: Guennou, C.; Auchère, F.; Soubrié, E.; Bocchialini, K.;
Parenti, S.; Barbey, N.
2012ApJS..203...26G Altcode: 2012arXiv1210.2302G
Differential emission measure (DEM) analysis is one of the most
used diagnostic tools for solar and stellar coronae. Being an inverse
problem, it has limitations due to the presence of random and systematic
errors. We present in this series of papers an analysis of the
robustness of the inversion in the case of SDO/AIA observations. We
completely characterize the DEM inversion and its statistical
properties, providing all the solutions consistent with the data along
with their associated probabilities, and a test of the suitability of
the assumed DEM model. While Paper I focused on isothermal conditions,
we now consider multithermal plasmas and investigate both isothermal and
multithermal solutions. We demonstrate how the ambiguity between noises
and multithermality fundamentally limits the temperature resolution
of the inversion. We show that if the observed plasma is multithermal,
isothermal solutions tend to cluster on a constant temperature whatever
the number of passbands or spectral lines. The multithermal solutions
are also found to be biased toward near-isothermal solutions around 1
MK. This is true even if the residuals support the chosen DEM model,
possibly leading to erroneous conclusions on the observed plasma. We
propose tools for identifying and quantifying the possible degeneracy
of solutions, thus helping the interpretation of DEM inversion.
---------------------------------------------------------
Title: On the Accuracy of the Differential Emission Measure
Diagnostics of Solar Plasmas. Application to SDO/AIA. I. Isothermal
Plasmas
Authors: Guennou, C.; Auchère, F.; Soubrié, E.; Bocchialini, K.;
Parenti, S.; Barbey, N.
2012ApJS..203...25G Altcode: 2012arXiv1210.2304G
Differential emission measure (DEM) analysis is a major diagnostic
tool for stellar atmospheres. However, both its derivation and its
interpretation are notably difficult because of random and systematic
errors, and the inverse nature of the problem. We use simulations with
simple thermal distributions to investigate the inversion properties
of SDO/AIA observations of the solar corona. This allows a systematic
exploration of the parameter space, and using a statistical approach
the respective probabilities of all the DEMs compatible with the
uncertainties can be computed. Following this methodology, several
important properties of the DEM inversion, including new limitations,
can be derived and presented in a very synthetic fashion. In this first
paper, we describe the formalism and we focus on isothermal plasmas
as building blocks to understand the more complex DEMs studied in the
second paper. The behavior of the inversion of AIA data being thus
quantified, and we provide new tools to properly interpret the DEM. We
quantify the improvement of the isothermal inversion with six AIA bands
compared to previous EUV imagers. The maximum temperature resolution
of AIA is found to be 0.03 log T<SUB>e</SUB> , and we derive a rigorous
test to quantify the compatibility of observations with the isothermal
hypothesis. However, we demonstrate limitations in the ability of AIA
alone to distinguish different physical conditions.
---------------------------------------------------------
Title: Studying Sun-Planet Connections Using the Heliophysics
Integrated Observatory (HELIO)
Authors: Pérez-Suárez, D.; Maloney, S. A.; Higgins, P. A.;
Bloomfield, D. S.; Gallagher, P. T.; Pierantoni, G.; Bonnin, X.;
Cecconi, B.; Alberti, V.; Bocchialini, K.; Dierckxsens, M.; Opitz,
A.; Le Blanc, A.; Aboudarham, J.; Bentley, R. B.; Brooke, J.; Coghlan,
B.; Csillaghy, A.; Jacquey, C.; Lavraud, B.; Messerotti, M.
2012SoPh..280..603P Altcode: 2012SoPh..tmp..215P
The Heliophysics Integrated Observatory (HELIO) is a software
infrastructure involving a collection of web services, heliospheric
data sources (e.g., solar, planetary, etc.), and event catalogues -
all of which are accessible through a unified front end. In this
paper we use the HELIO infrastructure to perform three case studies
based on solar events that propagate through the heliosphere. These
include a coronal mass ejection that intersects both Earth and Mars,
a solar energetic particle event that crosses the orbit of Earth, and
a high-speed solar wind stream, produced by a coronal hole, that is
observed in situ at Earth (L1). A ballistic propagation model is run as
one of the HELIO services and used to model these events, predicting
if they will interact with a spacecraft or planet and determining the
associated time of arrival. The HELIO infrastructure streamlines the
method used to perform these kinds of case study by centralising the
process of searching for and visualising data, indicating interesting
features on the solar disk, and finally connecting remotely observed
solar features with those detected by in situ solar wind and energetic
particle instruments. HELIO represents an important leap forward in
European heliophysics infrastructure by bridging the boundaries of
traditional scientific domains.
---------------------------------------------------------
Title: On the Thermal diagnostics of Coronal Loops with SDO/AIA
Authors: Guennou, Chloe; Parenti, Susanna; Bocchialini, Karine;
Soubrie, Elie; Auchere, Frederic; Barbey, Nicolas
2012cosp...39..675G Altcode: 2012cosp.meet..675G
With simultaneous observations in 6 coronal bands, AIA has the
capability to provide spectral diagnostics over an extended field of
view at high resolution and high cadence. Therefore, DEM diagnostics of
coronal loops can in principle be performed routinely for statistical
studies. We investigate here the pertinence of the DEM analysis with
AIA. The inevitable presence of noises and uncertainties, incompleteness
of the atomic physics databases lead to notable difficulties in the
inversion process. The complications involved in the derivation of
the DEM are one of the reasons of the controversial results regarding
the thermal structure and thus the heating scenario of the coronal
loops. The purpose of this work, based on a probabilistic approach, is
precisely to investigate the properties of the solutions, providing a
quantification of the DEM inversion problem robustness. The technique
relies on Monte Carlo simulations of observed intensities in the six
AIA coronal bands. The comparison between the known inputs and the
inversion results allows us to determine the degree of robustness. This
approach provides all the solutions consistent with the data along with
their associated probabilities, as well as a test of the validity of
the assumptions made on the DEM shape. Applications to SDO/AIA coronal
loops data are presented.
---------------------------------------------------------
Title: Homologous flares inducing EUV filament oscillations with
subsequent eruption
Authors: Bocchialini, K.; Koutchmy, S.; Solomon, J.; Tavabi, E.
2012EAS....55..335B Altcode:
We focus our analysis on an event which occurred at the W-limb on
May 30, 2003. The dynamical behavior of the filament, including
damped oscillations, was investigated with the CDS and EIT (SoHO)
experiments, as well as with Hα filtergrams (movies). The eruptive
phase is analyzed taking into account the approximate phasing with
other eruptive phenomena occurring at the same time or before, called
homologous flares and eruptions.
---------------------------------------------------------
Title: HELIO - A Research Environment for Heliophysics
Authors: Bentley, R. D.; Abourdarham, J.; Csillaghy, A.; Messerotti,
M.; Gallagher, P.; Bocchialini, K.; Jacquey, C.; Hapgood, M.
2012EGUGA..1411634B Altcode:
HELIO, the Heliophysics Integrated Observatory, is a research
infrastructure funded under Capacities programme of the EC's 7th
Framework Programme (FP7). It provides a collaborative environment where
scientists can discover, understand and model the connection between
solar phenomena, interplanetary disturbances and their effects on the
planets. The project is designed around a service-oriented architecture
with needed capabilities that support metadata curation and search,
data location and retrieval, and data processing and storage being
established as independent services. HELIO provides integrated access
to the data and metadata from the domains that constitute heliophysics
- solar, heliospheric, geophysics and planetary. More than 50 event
catalogues can be used in the search, together with just under 10
feature catalogues; data from more than 150 instruments from nearly
50 observatories can be accessed. A comprehensive user interface
is available and the serves can also be accessed through IDL; a
workflow tool provides the ability to combine services together and
it is possible to execute programmes on demand including propagation
models. We will report on the status of HELIO and the services that are
available and demonstrate how these resources can be used to address
use cases involving multiple spacecraft and modelling. We will also
describe how we hope to combine the tools developed by HELIO into a
Collaborative Research Environment for Heliophysics. We have been
holding a series of Coordinated Data Analysis Workshops (CDAW) in
which we demonstrate the capabilities of the project and participants
are able to use them to address science use cases. Two CDAWs have been
held so far, in Dublin and Trieste; a third will be held in February
2012 in Orsay, and a fourth is planned in May/June 2012. Typical use
cases relate to phenomena propagating from the Sun and being observed
by at least two observatories in different parts of the inner Solar
System. The HELIO Consortium includes thirteen groups from the UK,
France, Ireland, Italy, Switzerland, Spain and the US; the project
started in June 2009 and has a duration of 36 months
---------------------------------------------------------
Title: SOHO observations of oscillatory motions in an eruptive
filament: Intensity and velocity variations
Authors: Bocchialini, K.; Koutchmy, S.; Solomon, J.
2011sf2a.conf..369B Altcode:
The variations in intensity and velocity inside an eruptive filament,
observed on May 30, 2003 with CDS and EIT on-board SOHO, are analysed
in the transition region He I line and the coronal Mg X line. Vertical
oscillating motions of the filament with damped velocity oscillations
before its disappearance are revealed. The link between theses
oscillations, the flaring regions nearby and the filament eruption
is investigated.
---------------------------------------------------------
Title: Oscillatory motions observed in eruptive filaments
Authors: Bocchialini, K.; Baudin, F.; Koutchmy, S.; Pouget, G.;
Solomon, J.
2011A&A...533A..96B Altcode: 2011arXiv1107.0596B
Context. The origin of the variable component of the solar wind is of
great intrinsic interest for heliophysics and spaceweather, e.g. the
initiation of coronal mass ejections and the problem of mass loss
of all stars. It is also related to the physics of coronal neutral
sheets and streamers, which occur above lines of magnetic polarity
reversal. Filaments and prominences correspond to the cool coronal
component of these regions. <BR /> Aims: We examine the dynamical
behaviour of these structures where reconnection and dissipation
of magnetic energy in the turbulent plasma are occurring. The link
between the observed oscillatory motions and the eruption occurrence
is investigated in detail for two different events. <BR /> Methods:
Two filaments were analysed using two different datasets: time series of
spectra using a transition region line (He I at 584.33 Å) and a coronal
line (Mg X at 609.79 Å) measured with CDS on-board SOHO, observed on
May 30, 2003, and time series of intensity and velocity images from
the NSO/Dunn Solar Telescope in the Hα line on September 18, 1994
for the other. The oscillatory content was investigated using Fourier
transform and wavelet analysis and compared to different models. <BR
/> Results: In both filaments, oscillations are clearly observed,
in intensity and velocity in the He I and Mg X lines, in velocity in
Hα, with similar periods from a few minutes up to 80 min, with a main
range from 20 to 30 min, simultaneously with eruptions. Both filaments
exhibit vertical oscillating motions. For the filament observed in
the UV (He I and Mg X lines), we provide evidence of damped velocity
oscillations, and for the filament observed in the visible (Hα line),
we provide evidence that parts of the filament are oscillating, while
the filament is moving over the solar surface, before its disappearance.
---------------------------------------------------------
Title: HELIO: The Heliophysics Integrated Observatory
Authors: Bentley, R. D.; Csillaghy, A.; Aboudarham, J.; Jacquey, C.;
Hapgood, M. A.; Bocchialini, K.; Messerotti, M.; Brooke, J.; Gallagher,
P.; Fox, P.; Hurlburt, N.; Roberts, D. A.; Duarte, L. Sanchez
2011AdSpR..47.2235B Altcode:
Heliophysics is a new research field that explores the Sun-Solar System
Connection; it requires the joint exploitation of solar, heliospheric,
magnetospheric and ionospheric observations.HELIO, the Heliophysics
Integrated Observatory, will facilitate this study by creating an
integrated e-Infrastructure that has no equivalent anywhere else. It
will be a key component of a worldwide effort to integrate heliophysics
data and will coordinate closely with international organizations to
exploit synergies with complementary domains.HELIO was proposed under a
Research Infrastructure call in the Capacities Programme of the European
Commission’s 7th Framework Programme (FP7). The project was selected
for negotiation in January 2009; following a successful conclusion to
these, the project started on 1 June 2009 and will last for 36 months.
---------------------------------------------------------
Title: The SDO data centre at IDOC/MEDOC in France
Authors: Parenti, Susanna; Bocchialini, Karine; Soubrie, Elie;
Auchere, Frederic; Ballans, Herv; Buchlin, Eric; Gabriel, Alan;
Mercier, Claude; Poulleau, Gilles; Vial, Jean-Claude
2010cosp...38.2888P Altcode: 2010cosp.meet.2888P
The IDOC/MEDOC centre at the Institut d'Astrophysique Spatiale (IAS,
Université Paris 11/CNRS) has a long experience in solar data archiving
and distribution, including almost 15 years of data from SOHO, STEREO
and TRACE. The center is now expanding its activity and becoming a
Pˆle Thématique Solaire of the CNES and INSU/CNRS. Part of the new
activities of the centre will be linked to the arrival of the enormous
volume of the new SDO data. The center will be one of the three European
centers to receive and redistribute the data to the community. It will
also be the only European site to permanently store about 10% of the
data (mainly from AIA). In continuity with its previous activities,
SDO data will be included in the data visualization tool FESTIVAL
and it will provide new services, like tools for the solar feature
identification (filaments, EUV intensity fluctuations). We will present
an overview of the facilities and activities of the centre in relation
to the SDO data.
---------------------------------------------------------
Title: On the observations and possible interpretations of very long
period intensity oscillations of solar coronal loops
Authors: Solomon, Jacques; Auchere, Frederic; Bocchialini, Karine;
Gabriel, Alan; Tison, Emmanuelle
2010cosp...38.2853S Altcode: 2010cosp.meet.2853S
A comprehensive analysis of intensity oscillations in the Fe XII
line (19.5 nm) observed with EIT/SoHO in solar coronal loops during
solar cycle 23 (january 1997-september 2008) was performed. About
450 occurences of oscillations were obtained with periods ranging
between 3.4 and 13.6 hours and with durations up to about a
hundred hours. Interpratations in term of slow waves or of thermal
nonequilibrium were examined. However numerous inconsistencies arise
between current theories (in fact mostly expressed in terms of various
numerical simulations) and observations. Presently the lack of a direct
link between those very long oscillation periods and the characteristic
physical parameters of the loops (density, temperature, loop geometry)
hampers making progress in this major issue. This situation requires
an effort in a specific time analysis of the classical system of
equations of the problem: the question is examined from different
angles in relation to the data.
---------------------------------------------------------
Title: Distributing and mining SDO data in Europe
Authors: Parenti, Susanna; Delouille, Véronique; Dalla, Silvia;
Bocchialini, Karine; Ballans, Herv; Boyes, David; Chapman, Steve;
Hochedez, Jean-François; Mampaey, Benjamin; March, Mike S.; Soubrie,
Elie; Walsh, Robert
2010cosp...38.2883P Altcode: 2010cosp.meet.2883P
The properties of the highly dynamic Sun will soon be revealed by the
newly launched SDO, with data provided by its three instruments: AIA,
HMI and EVE. This suite will produce, for the first time in solar
physics, a large volume of data, equivalent to about 1.5 Tb/day,
by observing the full disk Sun continuously at high cadence. A
backbone network of data centres has been established to handle
these data and redistribute them to Europe. The Royal Observatory
of Belgium (Belgium) will receive the entire flow directly from the
Harvard-Smithsonian Center for Astrophysics. This will next be further
redistributed to University of Central Lancashire (United Kingdom),
and to Institut d'Astrophysique Spatiale (France). These institutes
will also permanently store part of the data. With such huge data rate,
it is necessary to develop automated algorithms that scan the data
and extract information related to important events or features. The
European partners have gathered within an ISSI team on 'Mining and
exploiting the NASA Solar Dynamics Observatory data in Europe', a.k.a
the Soldyneuro project. One of the outputs from the ISSI team will be
to use the feature recognition algorithms to populate the Heliophysics
Events Knowledgebase (HEK) hosted by LMSAL, and provide a service as
added value to the local database centers.
---------------------------------------------------------
Title: Using HELIO to study cross-disiplinary science problems using
data from multiple spacecraft
Authors: Bentley, Robert; Aboudarham, Jean; Messerotti, Mauro; Jacquey,
Christian; Gallagher, Peter T.; Hapgood, Mike; Bocchialini, Karine
2010cosp...38.1917B Altcode: 2010cosp.meet.1917B
The Heliophysics Integrated Observatory, HELIO, is creating a
collaborative environment where scientists can discover, understand
and model the connection between solar phenomena, inter-planetary
disturbances and their effects on the planets. HELIO will provide
integrated access to data from the solar, heliospheric, geophysics
and plan-etary domains and allow the user to undertake a search for
interesting events and phenomena based solely on metadata and data
products. The HELIO infrastructure will provide services to support
the search that can either be used independently or as part of a work
flow. The services include event and feature catalogues derived from
data from all the domains and a processing capability that will use
models to relate observations made in different part of the solar
system. We will describe how HELIO can be used to address science
problems that span the domains by allowing the user to track phenomena
as they propagate through the solar system and report on progress
to date. HELIO is a research infrastructure funded under Capacities
programme of the EC's 7th Frame-work Programme (FP7); the project
started in June 2009 and has a duration of 36 months. The HELIO
Consortium includes thirteen groups from the UK, France, Ireland,
Italy, Switzerland, Spain and the US.
---------------------------------------------------------
Title: Automatic detection and statistical analysis of intensity
oscillations in the solar corona with SDO
Authors: Auchere, Frederic; Bocchialini, Karine; Solomon, Jacques;
Gabriel, Alan; Tison, Emmanuelle
2010cosp...38.2863A Altcode: 2010cosp.meet.2863A
We present the generalization to SDO data of our automatic oscillation
detection algorithm. This technique was successfully tested using EIT
data on board SOHO at 19.5 nm from January 1997 to September 2008,
i.e almost the entire solar cycle 23. In the EIT data set we detected
400 oscillations whose periods range between 3.4 and 13.6 h with a
maximum around 6-7 hours. Most of the oscillations are localized in
coronal structures associated with active regions and last several
tens of hours. The AIA data will allow the detection of similar events
in several coronal temperature bands simultaneously, which will help
understand their physical nature.
---------------------------------------------------------
Title: Addressing Science Use Cases with HELIO
Authors: Bentley, R. D.; Aboudarham, J.; Csillaghy, A.; Jacquey,
C.; Hapgood, M. A.; Messerotti, M.; Gallagher, P.; Bocchialini, K.;
Hurlburt, N. E.; Roberts, D.; Sanchez Duarte, L.
2009AGUFMSH54A..06B Altcode:
The Heliophysics Integrated Observatory (HELIO) is a new VO project
funded under the EC's Seventh Framework Programme (FP7). It includes
thirteen partners scattered over six countries and is led by University
College London. HELIO is designed to support the heliophysics community
and is based on a Service Oriented Architecture. The services developed
by and integrated into HELIO can be used to address a wide range
of science problems; they can be used individually or as part of a
work-flow driven search engine that can use a propagation (or other)
model to help locate obervations that describe interesting phenomena. We
will describe and discuss how the components of HELIO could be used
to address science use cases, particularly how a user can adapt the
work flow to their own science interests. Networking is one of the
three Activities of the HELIO Integrated Infrastructure Initiatives
(I3) project. Within this activity we plan to involve the community in
all aspects of the design and testing of the HELIO system, including
determining which data and metadata should be included, how the quality
and content of metadata can be included, etc. We are investigating ways
of making HELIO "domain-aware" so that researchers who are specialists
in one of the communities that constitute heliophysics can easily
identify, access and use data they need from the other communities. We
will discuss how the community can help us develop this capability.
---------------------------------------------------------
Title: FESTIVAL: A Multiscale Visualization Tool for Solar Imaging
Data
Authors: Auchère, F.; Soubrié, E.; Bocchialini, K.; LeGall, F.
2008SoPh..248..213A Altcode: 2008SoPh..tmp...59A
Since 4 December 2006, the SECCHI instrument suites onboard the
two STEREO A and B probes have been imaging the solar corona and the
heliosphere on a wide range of angular scales. The EUVI telescopes have
a plate scale of 1.7 arcseconds pixel<SUP>−1</SUP>, while that of the
HI2 wide-angle cameras is 2.15 arcminutes pixel<SUP>−1</SUP>, i.e. 75
times larger, with the COR1 and COR2 coronagraphs having intermediate
plate scales. These very different instruments, aimed at studying
Coronal Mass Ejections and their propagation in the heliosphere,
create a data visualization challenge. This paper presents FESTIVAL,
a SolarSoftware package originally developed to be able to map the
SECCHI data into dynamic composite images of the sky as seen by the
STEREO and SOHO probes. Data from other imaging instruments can also
be displayed. Using the mouse, the user can quickly and easily zoom in
and out and pan through these composite images to explore all spatial
scales from EUVI to HI2 while keeping the native resolution of the
original data. A large variety of numerical filters can be applied,
and additional data (i.e. coordinate grids, stars catalogs, etc.) can
be overlaid on the images. The architecture of FESTIVAL is such that
it is easy to add support for other instruments and these new data
immediately benefit from the already existing capabilities. Also,
because its mapping engine is fully 3D, FESTIVAL provides a convenient
environment to display images from future out-of-the-Ecliptic solar
missions, such as Solar Orbiter or Solar Probe.
---------------------------------------------------------
Title: A Contribution to the Understanding of Chromospheric
Oscillations
Authors: Baudin, F.; Ibarra, E.; Avrett, E. H.; Vial, J. -C.;
Bocchialini, K.; Costa, A.; Lemaire, P.; Rovira, M.
2007SoPh..241...39B Altcode:
We present SUMER/SOHO UV measurements of chromospheric oscillations
of intensity, velocity, and linewidth observed in C I, S I, O I, and
C II lines, which are formed in the altitude range from 1000 km to
2000 km above τ<SUB>500</SUB>=1. Oscillations in lines originating
at similar altitudes exhibit different behaviors which we discuss in
terms of the formation of the lines.
---------------------------------------------------------
Title: Rotational Tomography of the Solar Corona-Calculation of the
Electron Density and Temperature
Authors: Barbey, Nicolas; Auchère, Frédéric; Rodet, Thomas;
Bocchialini, Karine; Vial, Jean-Claude
2006ESASP.617E..82B Altcode: 2006soho...17E..82B
No abstract at ADS
---------------------------------------------------------
Title: Two Observations of Damped Oscillations During Filament
Eruptions: A Signature of the Eruptions?
Authors: Pouget, G.; Bocchialini, K.; Solomon, J.
2006ESASP.617E.141P Altcode: 2006soho...17E.141P
No abstract at ADS
---------------------------------------------------------
Title: Oscillations in a solar filament: first observation of long
periods in the HeI 584.33 Å line, modelling and diagnostic
Authors: Pouget, G.; Bocchialini, K.; Solomon, J.
2006A&A...450.1189P Altcode:
Three long observations of filaments were carried out in the 584.33
HeI line during MEDOC campaigns in November 2003 and November 2004,
by the Coronal Diagnostic Spectrometer onboard SOHO. Their duration was
15-16 h and the temporal resolution was 20 s, allowing measurements of
the entire range of periodicities theoretically expected in a filament
(particularly both the short periods, less than 10 min, and the long
ones, more than 40 min). Fourier analysis of the Doppler velocities
in the filament allows us to detect oscillations over a wide range,
and particularly very slow velocity oscillations (5-6 h) that were
not detected previously. We test an earlier interpretation of these
velocity oscillations in the prominence model of Joarder & Roberts
(1993, A&A, 277, 225), who treat the prominence as a slab. We used
a systematic method to identify the six fundamental modes predicted
by the model among the numerous frequencies detected. Identification
of these modes - and especially the slowest one, the slow kink mode -
provides a complete diagnostic of the filament in terms of the Alfvén
speed, temperature, and angle between the magnetic field and the main
axis of the filament.
---------------------------------------------------------
Title: From the Sun to the Earth: impact of the 27-28 May 2003 solar
events on the magnetosphere, ionosphere and thermosphere
Authors: Hanuise, C.; Cerisier, J. C.; Auchère, F.; Bocchialini,
K.; Bruinsma, S.; Cornilleau-Wehrlin, N.; Jakowski, N.; Lathuillère,
C.; Menvielle, M.; Valette, J. -J.; Vilmer, N.; Watermann, J.; Yaya, P.
2006AnGeo..24..129H Altcode:
During the last week of May 2003, the solar active region AR 10365
produced a large number of flares, several of which were accompanied
by Coronal Mass Ejections (CME). Specifically on 27 and 28 May three
halo CMEs were observed which had a significant impact on geospace. On
29 May, upon their arrival at the L1 point, in front of the Earth's
magnetosphere, two interplanetary shocks and two additional solar
wind pressure pulses were recorded by the ACE spacecraft. The
interplanetary magnetic field data showed the clear signature of a
magnetic cloud passing ACE. In the wake of the successive increases
in solar wind pressure, the magnetosphere became strongly compressed
and the sub-solar magnetopause moved inside five Earth radii. At
low altitudes the increased energy input to the magnetosphere was
responsible for a substantial enhancement of Region-1 field-aligned
currents. The ionospheric Hall currents also intensified and the entire
high-latitude current system moved equatorward by about 10°. Several
substorms occurred during this period, some of them - but not all -
apparently triggered by the solar wind pressure pulses. The storm's
most notable consequences on geospace, including space weather effects,
were (1) the expansion of the auroral oval, and aurorae seen at mid
latitudes, (2) the significant modification of the total electron
content in the sunlight high-latitude ionosphere, (3) the perturbation
of radio-wave propagation manifested by HF blackouts and increased
GPS signal scintillation, and (4) the heating of the thermosphere,
causing increased satellite drag. We discuss the reasons why the May
2003 storm is less intense than the October-November 2003 storms,
although several indicators reach similar intensities.
---------------------------------------------------------
Title: Toward a Virtual Observatory for Solar System Plasmas: an
exceptional scientific opportunity
Authors: Jacquey, C.; Bocchialini, K.; Aboudarham, J.; Meunier, N.;
Andre, N.; Genot, V.; Harvey, C.; Budnik, E.; Hitier, R.; Gangloff,
M.; Bouchemit, M.
2006epsc.conf..714J Altcode:
During the coming years, the "Solar System Plasma" environment will
be explored by an exceptional set of observatories : RHESSI, SOHO,
STEREO, SOLAR-B and ground based observatories will all provide
continuous observations of the Sun and its corona. In situ plasma and
field measurements will be obtained at and near Mercury (MESSENGER),
Venus (VEX), Earth (ACE, WIND, GEOTAIL, CLUSTER, THEMIS), Mars (MEX,
MGS) and Saturn (CASSINI), and inside the heliosphere (STEREO, ULYSSES,
VOYAGER). These data will be complemented by UV and radio astronomical
observations of Jovian, Saturnian and terrestrial auroral activity. This
wealth of data will offer previously unequalled opportunities to study
(i) global and multi-scale phenomena of the inner heliosphere (ii)
the propagation of the solar perturbations and space meteorology,
(iii) local interplanetary conditions around planets and (iv) the
comparison of the ionised environments of various planets. However,
the exploitation of all these data is a major technical challenge, as it
requires accessing heterogeneous data from diverse origins to perform an
integrated study using software tools appropriate for analysis of the
phenomena observed. Moreover, the huge amount of data to manage coming
from future space and ground based instruments requires extraction
that could no more be done by hand, but automatically. This challenge
is unlikely to be met by instrument teams or laboratories working
individually ; it requires collaboration of the whole international
community through a Virtual Observatory. The Europlanet/IDIS prototype
will give a foretaste of what will be achievable by a Virtual
Observatory for planetology. The overlap in functionality between a
"Planetary VO" and a "Solar System Plasma VO" remains to be defined,
but both are undoubtedly essential and complimentary components of any
Solar System VO. In this paper, we present potential science cases
in Space Plasma, which we then use to identify requirements for the
access and analysis tools needed to exploit the promised exceptional
harvest of solar and in situ plasma data.
---------------------------------------------------------
Title: The Beleinos cornerstone: the Sun, the star close to Earth
Authors: Appourchaux, T.; Auchère, F.; Bocchialini, K.; Bonnet,
R. M.; Gabriel, A.; Vial, J. -C.
2005ESASP.588..389A Altcode: 2005tssc.conf..389A
No abstract at ADS
---------------------------------------------------------
Title: About the fe XIV 530.3 NM Line Emissions of the Middle Corona
Authors: Koutchmy, S.; Contesse, L.; Viladrich, Ch.; Vilinga, J.;
Bocchialini, K.
2005ESASP.600E..26K Altcode: 2005ESPM...11...26K; 2005dysu.confE..26K
No abstract at ADS
---------------------------------------------------------
Title: The August 11th, 1999 CME
Authors: Koutchmy, S.; Baudin, F.; Bocchialini, K.; Daniel, J. -Y.;
Delaboudinière, J. -P.; Golub, L.; Lamy, P.; Adjabshirizadeh, A.
2004A&A...420..709K Altcode:
We present here a set of observations, space borne and ground based,
at different wavelengths, of the solar corona at and after the time of
the total solar eclipse of August 11{th}. It is used to consider some
unusual features of the coronal dynamics related to a limb Coronal Mass
Ejection (CME) observed after the total eclipse. The complementary
aspect of simultaneous ground-based and space-borne observations
of the corona is used to produce an accurate composite image of the
White Light (W-L) corona before the CME. A high arch system (possibly
a dome-like structure, with large cavities inside but without a cusp
further out) which appeared on the eclipse W-L images, is suggested to
be a large-scale precursor of the CME, well preceding the eruption of
the top part of the brightest prominence recorded in W-L. This bright
prominence is shown as a filament in absorption using the Transition
Region And Corona Explorer (TRACE) images taken in different coronal
lines. The analysis of the images of the Large Angle and Spectrometric
Coronograph (LASCO) on board the Solar and Heliospheric Observatory
(SoHO), showing the progression of the CME, is discussed in an attempt
to make a connection with the surface event. A SoHO-EIT (Extreme
UV Imager Telescope) image sequence details the prominence eruption
and shows the sudden heating processes of the ejected parts. We found
that there is no reason to assume that the huge cavity is significantly
destabilised well before the eruption of the upper part of the low-lying
bright twisted filament which coincides with the position of one of
the legs of the high arch. Observations are still compatible with the
assumption of both the break-out model and of the flux rope erupting
model as a result of a shear or of an increasing poloıdal magnetic
flux from below. We stress the possible role of buoyancy of the giant
cavity as a destabilizing factor leading to the CME, noticing that some
motion of coronal material back toward the surface can be seen during at
least the first phase of the CME, from both EIT and LASCO observations.
---------------------------------------------------------
Title: Analysis of the oscillations in the solar prominences with Soho
(CD-SUMER)
Authors: Pouget, G.; Bocchialini, K.; Solomon, J.
2004cosp...35.4231P Altcode: 2004cosp.meet.4231P
Solar prominences (also called filaments when they are seen on the
disk) often exhibit oscillatory movements. These oscillations may
result in instability, thus causing the ejection of some of the
prominence's mass, which contributes to the solar wind. By studying
the different oscillation modes that occur inside prominences,
we would intend to infer characteristic predicting signatures of
CMEs. Series of observations were carried out in 2003 by the SUMER
and CDS UV spectrometers on SoHO, simultaneously in several spectral
lines, and with long duration for some events (>16 hours). The
Fourier analysis of the Doppler velocities in the filament allows us
to detect oscillations (after having set a detection threshold). A
comparison is done between the observed frequencies and the frequencies
calculated considering the prominence model of Joarder & Roberts
(1993). By identifying observed and calculated frequencies, we were
able in general to find four of the six oscillation modes of the
model. This identification provides a diagnostic of the filament, in
terms of magnetic field, temperature, density, and angle between the
magnetic field and the main axis of the filament. More specifically,
in the case of the longer sequences, we are presently interested in
identifying the lower frequency modes of oscillations in order to put
more constraints on the prominence physical parameters.
---------------------------------------------------------
Title: The solar high-resolution imager - coronagraph LYOT mission
Authors: Vial, Jean-Claude; Song, Xueyan; Lemaire, Philippe; Gabriel,
Alan H.; Delaboudiniere, Jean-Pierre; Bocchialini, Karine; Koutchmy,
Serge L.; Lamy, Philippe L.; Mercier, Raymond; Ravet, Marie Francoise;
Auchere, Frederic
2003SPIE.4853..479V Altcode:
The LYOT (LYman Orbiting Telescope) solar mission is proposed to
be implemented on a micro-satellite of CNES (France) under phase A
study. It includes two main instruments, which image the solar disk
and the low corona up to 2.5 R<SUB>o</SUB> in the H I Lyman-α line
at 121.6 nm. The spatial resolution is about 1” for the disk and
2.5” for corona. It also carries an EIT-type telescope in the He II
(30.4 nm) line. The coronagraph needs a super polished mirror at the
entrance pupil to minimize the light scattering. Gratings and optical
filters are used to select the Lyman-α wavelength. VUV cameras with
2048×2048 pixels record solar images up to every 10 seconds. The
satellite operates at a high telemetry rate (more then 100 kb/s,
after onboard data compression). The envisaged orbits are either
geostationary or heliosynchronous. Possible launch dates could be end
of 2006 - beginning of 2007.
---------------------------------------------------------
Title: The August 11th, 1999 total eclipse CME
Authors: Koutchmy, S.; Baudin, F.; Bocchialini, K.; Delaboudinière,
J. -P.; Adjabshirizadeh, A.
2002ESASP.477...55K Altcode: 2002scsw.conf...55K
We use spaceborne observations and ground-based eclipse observations
to analyse the spectacular W-limb CME which occurred several hours
after the totality in Iran. The underlying high arch system (possibly
a dome-like structure with cavities inside) which appeared on the
eclipse White-Light (W-L) images, is suggested to be a large scale
precursor of the CME, taking into account the related coronal cavities
(as measured from the broadening of the green Fe XIV line) and the
properties of the inserted prominence which erupted during the CME.
---------------------------------------------------------
Title: On a mechanism of intensification of field-aligned currents
at the solar chromosphere-quiescent prominence boundaries
Authors: Nenovski, P.; Dermendjiev, V. N.; Detchev, M.; Vial, J. -C.;
Bocchialini, K.
2001A&A...375.1065N Altcode:
Field-aligned electric currents (FAC) are assumed to support various
prominence configurations and it is usually supposed that the
quiescent prominence (QP) destabilisation can be initiated by some
plasma instability. In this work we study another possibility of QP
destabilisation connected with FAC changes. Such a destabilisation may
occur when FAC flowing along a loop-shaped QP structure are intensified
by bouncing surface MHD modes, presumably generated by motions in
the photosphere under, or adjacent to, the QP. The MHD disturbances
at the prominence “feet” propagate upwards as Alfven waves and
surface modes. We study the possibility that the generated MHD modes,
which carry FAC, bounce in the loop-shaped QP structure, provided that
they undergo multiple reflection at the prominence feet. This is an
interesting physical situation leading to intensification of FAC and
promising to be another source of QP destabilisation.
---------------------------------------------------------
Title: Joint EUV/Radio Observations of a Solar Filament
Authors: Chiuderi Drago, F.; Alissandrakis, C. E.; Bastian, T.;
Bocchialini, K.; Harrison, R. A.
2001SoPh..199..115C Altcode:
In this paper we compare simultaneous extreme ultraviolet (EUV) line
intensity and microwave observations of a filament on the disk. The
EUV line intensities were observed by the CDS and SUMER instruments on
board SOHO and the radio data by the Very Large Array and the Nobeyama
radioheliograph. The main results of this study are the following: (1)
The Lyman continuum absorption is responsible for the lower intensity
observed above the filament in the EUV lines formed in the transition
region (TR) at short wavelengths. In the TR lines at long wavelengths
the filament is not visible. This indicates that the proper emission of
the TR at the filament top is negligible. (2) The lower intensity of
coronal lines and at radio wave lengths is due to the lack of coronal
emission: the radio data supply the height of the prominence, while EUV
coronal lines supply the missing hot matter emission measure (EM). (3)
Our observations support a prominence model of cool threads embedded
in the hot coronal plasma, with a sheath-like TR around them. From the
missing EM we deduce the TR thickness and from the neutral hydrogen
column density, derived from the Lyman continuum and He i absorption,
we estimate the hydrogen density in the cool threads.
---------------------------------------------------------
Title: Dynamics of a Quiescent Solar Prominence Observed with the
SUMER/SOHO Instrument
Authors: Bocchialini, K.; Costa, A.; Domenech, G.; Rovira, M.; Vial,
J. C.; Wingfield, K.
2001SoPh..199..133B Altcode:
We present the results obtained from analyzing SUMER/SOHO observational
data of a quiescent solar prominence. The studied prominence is made of
complex structures. From the 1-hr data set, we derive characteristic
frequencies in terms of intensity and velocity oscillations, as
measured in 4 transition-region lines. The presence of different types
of frequencies is detected: chromospheric oscillations and intermediate
periods (6 min to 12 min). This result suggests that these oscillations
are transmitted by the magnetic fields from the chromosphere to the
transition region.
---------------------------------------------------------
Title: An Observational Test for Solar Atmospheric Heating
Authors: van Driel-Gesztelyi, L.; Démoulin, P.; Ireland, J.; Thompson,
B.; Fludra, A.; Oláh, K.; Kövári, Zs.; Harra, L. K.; Mandrini,
C. H.; Bocchialini, K.; Orlando, S.
2001IAUS..203..514V Altcode:
We study the evolution of the emissivity and heating correlated with
magnetic observables of an active region from its birth throughout
its decay during seven solar rotations (July-Dec. 1996). Taking one
"snapshot" per g:wq: Command not found. time of flares, we analyse
multi-wavelength and multi-instrument data obtained from SOHO (MDI,
EIT, CDS and SUMER), Yohkoh (SXT), GOES, SOLSTICE and 10.7 cm radio
data from DRAO, Canada. We utilise our results to test the validity
of coronal heating models. We find that models which are based on
the dissipation of stressed, current-carrying magnetic fields are in
better agreement with the observations than the models which attribute
coronal heating to the dissipation of MHD waves.
---------------------------------------------------------
Title: Oscillations Observed in Intensity and Velocity for a
Quienscent Prominence
Authors: Bocchialini, K.; Costa, A.; Domenech, G.; Rovira, M.; Vial,
J. -C.
2001IAUS..203..419B Altcode:
We present the results obtained from analyzing SUMER/SOHO observation
data of a solar prominence. The studied prominence can be characterized
as having a complex structure. From the 1 hour data set, we derived
characteristic frequencies in terms of intensity and velocity
oscillations, for 4 transition region lines. The homogenity in the
characteristic frequencies suggests the engagemente of coronal
oscillations with the chromospheric structure. The presence of
different types of frequencies is detected: chromospheric oscillations,
intermediate periods (6min to 12min) and also long periods (25min to
51min). This result suggests that these oscillations are transmitted
by the magnetic fields.
---------------------------------------------------------
Title: Microscale Structures on the Quiet Sun and Coronal Heating
Authors: Aletti, V.; Velli, M.; Bocchialini, K.; Einaudi, G.;
Georgoulis, M.; Vial, J. -C.
2000ApJ...544..550A Altcode:
We present some results concerning transient brightenings on the quiet
Sun, based on data from the Extreme-Ultraviolet Imaging Telescope on
board the Solar and Heliospheric Observatory. Histograms of intensity
are found to be well fitted by χ<SUP>2</SUP> distributions for
small values of the intensity, while at high intensities power-law
distributions are always observed. Also, the emission presents the
same statistical properties when the resolution is downgraded by local
averaging; i.e., it appears to be self-similar down to the resolution
scale of the instruments. These properties are characteristic of
the emission from a forced turbulent system whose dissipation scale
is much smaller than the pixel dimension. On the basis of the data
presented as well as other published results and our present theoretical
understanding of MHD turbulence, we discuss the realism of the nanoflare
scenario of coronal heating.
---------------------------------------------------------
Title: Observational Signatures of Microscale Heating
Authors: Bocchialini, K.; Aletti, V.; Vial, J. -C.; Lemaire, P.
1999ESASP.448..539B Altcode: 1999ESPM....9..539B; 1999mfsp.conf..539B
No abstract at ADS
---------------------------------------------------------
Title: Eclipse of August 11, 1999: White-light Images and Simultaneous
EIT/SOHO Observations
Authors: Adjabshirizadeh, A.; Baudin, F.; Bocchialini, K.;
Delaboudinière, J. -P.; Grorod, P. -A.; Koutchmy, S.; Laal Aaly,
M.; Lamy, P.; Lochard, J.; Mouette, J.
1999ESASP.448.1283A Altcode: 1999ESPM....9.1283A; 1999mfsp.conf.1283A
No abstract at ADS
---------------------------------------------------------
Title: Research Of Micro-Scale Coronal Heating Signatures
Authors: Aletti, V.; Bocchialini, K.
1999ESASP.446..113A Altcode: 1999soho....8..113A
Bright points, small and short lifetime structures, appear permanentely
in the solar atmopsphere and could be consideres as intermittent
energetic burst. They could be the result of the superpositioon of
non-observable small scales events, characterized by an intensity
distribution that follows a powerlaw, as obtained in SOC and MHD
models. Several brights points are indentifiable in the quiet Sun
observed by EIT/SoHO. We have performed a statistical analysis in
those brights points in order to determine the index of the power law
and to compare this index with the models's one.
---------------------------------------------------------
Title: Long-Term Evolution Of Emissivity And Heating In A Solar
Active Region
Authors: van Driel-Gesztelyi, L.; Thompson, B.; Démoulin, P.; Orlando,
S.; Bocchialini, K.; Oláh, K.; Kövári, Z.; Deforest, C.; Khan,
J.; Fludra, A.; Mandrini, C.
1999ESASP.446..663V Altcode: 1999soho....8..663V
We study the evolution of the heating and emissivity of an active
region from its birth throughout its decay during six solar rotations
(July-Nov. 1996). We analyse multi-wavelength and multi-instrument
data obtained from SOHO (EIT, SUMER, CDS, MDI), Yohkoh (SXT), GOES
and 10.7cm radio data from DRAO, Canada. We take one "snapshot" per
rotation at the time of the central meridian passage (CMP) of the
AR, outside of time of flares, which appears to be representative
enough to allow us to make some general conclusions about the
long-term evolution. Deriving physical parameters like intensity
(flux), temperature and emission measure of the entire AR vs. time,
we formulate mathematically the change in radiation emitted by the
decaying AR at several wavelengths. Combining the emissivity data with
the evolution of magnetic flux density as the flux is being dispersed
by small- and larger-scale convective motions, we make an attempt to
understand the physics behind the emission and heating. We also analyse
the effects of flaring on the heating of the AR, and study whether and
how the flare properties evolve during the life of the active region.
---------------------------------------------------------
Title: Plasma Diagnostics Of A Solar Prominence Observed On 12 June
1997 by EIT, Sumer And CDS
Authors: Madjarska, M. S.; Vial, J. -C.; Bocchialini, K.; Dermendjiev,
V. N.
1999ESASP.446..467M Altcode: 1999soho....8..467M
The plasma diagnostics of a quiescent prominence observed on June 12,
1997 with SUMER, CDS and EIT instruments aboard SOHO in the frame
of Joint Observing Programme 9 has been made. Two sets of SUMER
observations were taken in the four spectral lines Si IV 1393.755,
1402.770 (6-8 10<SUP>4</SUP> K) and O IV 1401.156, 1404.812 (1.7-2.0
10<SUP>5</SUP> K) at two different slit positions on the prominence
body. The relative line-of-sight velocities using both Si IV 1393.755
and 1402.770 lines are derived. The electron density (derived
from the intensity ratio of O IV 1401.156 to 1404.812 lines) in the
prominence-corona interface is determined for both slit positions. CDS
obtained 10 rasters in Si X 347.40, He I 584.33, Si X 356.04, Fe XVI
360.76, Mg IX 368.06, O V 629.73 lines covering a temperature range
from 10<SUP>4</SUP> to 10<SUP>6</SUP> K. By analysing the CDS spectra
in He I and O V ions the relative line-of-sight velocity maps with
regards to the quiet sun are derived.
---------------------------------------------------------
Title: Simultaneous LASCO/1998-Eclipse Observations Of A Large-Scale
Polar Event
Authors: Zhukov, A.; Koutchmy, S.; Lamy, Ph.; Delaboudinière,
J. -P.; Delannée, C.; Bocchialini, K.; Guisard, S.; Filippov, B.;
Veselovsky, I.
1999ESASP.446..731Z Altcode: 1999soho....8..731Z
A relatively faint but large scale polar region event was observed
in Aug. 1996 by Boulade et al. 1998 (SoHO SP 404, 217); we first
reconsider this event which has been related to a high latitude
filament disappearance. We continue the study of this class of events by
analyzing the large scale restructuring which occurred above the N-Pole
region at the time of the last Feb. 26, 1998 total solar eclipse. Well
calibrated WL-eclipse images are used to provide the absolute values
of electron densities of the quasi-radial structure appearing at
the feet of the event. This structure can also be considered as a
type of abnormally broad and curved polar plume, a type of activity
already reported in the literature. Unfortunately, the examination
of sequences of EIT images taken at that time seems to indicate that
the roots of the structure are on the back side of the Sun. However
the most impressive effects are seen in the high polar region, at
several radii, based on the analysis of processed Lasco-C2 difference
images. Large proper motions are deduced over density structures. Both
these events confirm that polar regions are indeed showing a new class
of CME activity (possibly related to the Hewish's CMEs), which is seen
inside coronal holes. A whole set of interesting questions is then
appearing to understand the occurrence of a polar CME propagating in
the heart of a large unipolar magnetic region of the corona.
---------------------------------------------------------
Title: Propagating Magneto-Acoustic Waves in the Network
Authors: Baudin, F.; Bocchialini, K.; Koutchmy, S.
1999ASPC..184..232B Altcode:
The analysis of spectroscopic data taken in the chromospheric network
is interpreted as evidence for propagating waves. These waves are
seen from the photospheric level propagating upward to the highest
levels of the chromosphere at velocities around 40 km/s, suggesting a
magneto-acoustic nature. We note the lack of an adequate one-dimensional
model of the solar chromosphere to interpret these data.
---------------------------------------------------------
Title: Multiresolution wavelet analysis of SUMER/SOHO observations
in a solar prominence
Authors: Blanco, S.; Bocchialini, K.; Costa, A.; Domenech, G.; Rovira,
M.; Vial, J. -C.
1999SoPh..186..281B Altcode:
We have studied through a multiresolution wavelet analysis the
oscillations in a limb prominence. Intensity fluctuations in time and
height corresponding to different lines of Si iv and O iv observed
with SUMER on board SOHO have been analyzed in the wavelet bands of
J<SUB>3</SUB>= 1 min 36 s to 3 min 12 s and J<SUB>4</SUB>=3 min 12
s to 6 min 24 s. For all species, oscillations in the J<SUB>4</SUB>
band were dominant. We found relevant differences between the behavior
of line D<SUB>1</SUB> (1393.76 Å) corresponding to Si iv and the set
D<SUB>2</SUB> (1401.16 Å), D<SUB>3</SUB> (1404.81 Å), D<SUB>4</SUB>
(1402.77 Å) corresponding to O iv, O iv and Si iv respectively. We
also report the identification of a pulse in the intensity of the line
D<SUB>1</SUB> that appears in the range of 15-20 min. This disturbance
seems to travel with a speed of about 170 km s<SUP>−1</SUP>.
---------------------------------------------------------
Title: Oscillations of the upper chromosphere
Authors: Gouttebroze, P.; Vial, J. -C.; Bocchialini, K.; Lemaire,
P.; Leibacher, J. W.
1999SoPh..184..253G Altcode:
Variations of intensity and wavelength in several UV lines have been
observed with the SUMER spectroheliometer onboard SOHO, and they have
been analysed to obtain oscillation spectra and phase differences
between lines of different ions. Lines intensities of neutral or
singly ionized atoms (with temperature of formation ≤ 30 000 K)
exhibit an increase of oscillatory power between 2.5 and 7 mHz, which
may be considered as the signature of p modes. Lines of highly ionized
elements (with a temperature of formation ≥ 50 000 K) yield power
spectra which are continuously decreasing with frequency. Brightness
variations of the continuum at different wavelengths between 1000
and 1400 Å present oscillations in the same frequency range. Thus,
p modes seem to be efficiently stopped by the transition region. No
clear evidence is found for the existence of a chromospheric oscillation
mode. Phase comparisons between lines formed at different altitudes
(in particular Si i and Si ii) indicate that these lines oscillate in
phase, within the precision of the measurements.
---------------------------------------------------------
Title: Dinámica y frecuencias características de una protuberancia
solar observada con los instrumentos SUMER y CDS/SOHO
Authors: Rovira, M.; Costa, A.; Bocchialini, K.
1999BAAA...43...22R Altcode:
La estructura de la protuberancia estudiada puede dividirse en
cuatro regiones. A partir del análisis de las imágenes del CDS
y los espectros del SUMER utilizando técnicas de multiresolución
con Wavelets se obtuvieron las frecuencias y velocidades relativas
de cada una de las regiones. Se observan frecuencias características
del orden de los 5 min y otras de largo período. Se obtuvo una fuerte
anticorrelación entre las intensidades y las velocidades Doppler. La
presencia de las oscilaciones de 5 min en todas las regiones sugieren
el acoplamiento entre la estructura cromosférica y la protuberancia.
---------------------------------------------------------
Title: Solar chromospheric structures observed in UV ressonance
lines : a multivariate analysis approach
Authors: Patsourakos, S.; Bocchialini, K.; Vial, J. -C.
1999CR2...322..337P Altcode:
We present the results of a statistical analysis carried out from a data
base of 6 solar chromospheric emission lines recorded simultaneously
and with high spectral resolution. An empirical and a clustering method
for separating the different solar structures contributions have been
used and been found in a good agreement. Mean profiles corresponding to
the different populations have been built. Correlations of different
parameters for each profile allowed us to deduce different properties
of the solar chromosphere, such as the existence of magnetic canopies
and downflows in active regions.
---------------------------------------------------------
Title: Search for Signatures of a Coronal Hole in Transition Region
Lines Near Disk Center
Authors: Lemaire, P.; Bocchialini, K.; Aletti, V.; Hassler, D.;
Wilhelm, K.
1999SSRv...87..249L Altcode:
The analysis of data taken by SUMER near disk center, where a small
coronal hole is observed in EIT images, is performed. From the
measurements of Doppler non-thermal velocities and intensities, we
search for the diagnostics and the signature of small scale structures
in the coronal hole using transition region lines. Transition region
lines in the range of 7 × 10<SUP>4</SUP> K to 2.5 × 10<SUP>5</SUP>
K have a non-thermal velocity excess of 4.0 to 5.5 km s<SUP>-1</SUP>
relative to the contiguous quiet Sun. While the average intensity is
lower in the coronal hole than in the quiet area, this result shows
an increase of turbulence at the base of the high speed solar wind.
---------------------------------------------------------
Title: Solar chromospheric structures observed in UV resonance lines:
a multivariate analysis approach.
Authors: Patsourakos, S.; Bocchialini, K.; Vial, J. -C.
1998CRASB.326..337P Altcode:
The authors present the results of a statistical analysis carried out
from a data base of six solar chromospheric emission lines recorded
simultaneously and with high spectral resolution. An empirical and
a clustering method for separating the different solar structure
contributions have been used and found to be in good agreement. Mean
profiles corresponding to the different populations have been
built. Correlations of different parameters for each profile allowed
one to deduce different properties of the solar chromosphere, such as
the existence of magnetic canopies and downflows in active regions.
---------------------------------------------------------
Title: Statistical analysis of solar bright points observed with
the SOHO spacecraft.
Authors: Régnier, S.; Bocchialini, K.; Vial, J. -C.; Delaboudinière,
J. -P.; Thompson, W.
1998CRASB.326..211R Altcode: 1998CR2...326..211R
Bright points, small and short lifetime structures, appear permanently
in the atmosphere and could be associated with magnetic reconnections,
potential sources of coronal heating. Such structures have been
observed with the coronal instruments on-board SOHO and a statistical
analysis was carried out in order to find the signature of very small
scale structures.
---------------------------------------------------------
Title: About polar ejection events and surges
Authors: Loucif, M. L.; Koutchmy, S.; Stellmacher, G.; Georgakilas,
A.; Bocchialini, K.; Delaboudinière, J. -P.
1998ESASP.421..299L Altcode: 1998sjcp.conf..299L
No abstract at ADS
---------------------------------------------------------
Title: Wave Activity and Prominence Eruption
Authors: Baudin, F.; Bocchialini, K.; Delannee, C.; Koutchmy, S.;
Stellmacher, G.; Shibata, K.; Veselovsky, I. S.; Panasenko, O. A.;
Zhukov, A. N.
1998ASPC..150..314B Altcode: 1998IAUCo.167..314B; 1998npsp.conf..314B
No abstract at ADS
---------------------------------------------------------
Title: EUV and Microwave Observations of a Filament
Authors: Chiuderi-Drago, F.; Bocchialini, K.; Lamartinie, S.;
Vial, J. -C.; Bastian, T.; Alissandrakis, C. E.; Harrison, R.;
Delaboudiniere, J. -P.; Lemaire, P.
1998ASPC..150...55C Altcode: 1998IAUCo.167...55C; 1998npsp.conf...55C
No abstract at ADS
---------------------------------------------------------
Title: Quiescent filament diagnostic.
Authors: Lamartinie, S.; Bocchialini, K.; Vial, J. -C.; Chiuderi-Drago,
F.; Harrison, R.; Alissandrakis, C. E.
1998joso.proc..139L Altcode:
UV observations of a quiescent filament were performed on July 28,
1996 by SUMER and CDS, two spectrometers onboard SOHO.
---------------------------------------------------------
Title: White-light polar plumes from solar eclipses
Authors: Koutchmy, S.; Bocchialini, K.
1998ESASP.421...51K Altcode: 1998sjcp.conf...51K
No abstract at ADS
---------------------------------------------------------
Title: Space solar physics : theoretical and observational issues
in the context of the SOHO mission
Authors: Vial, Jean Claude; Bocchialini, Karine; Boumier, Patrick
1998LNP...507.....V Altcode: 1998sspt.conf.....V
No abstract at ADS
---------------------------------------------------------
Title: Eclipse WL polar plumes: what is the connection with the
disk activity?
Authors: Koutchmy, Serge; Bocchialini, Karine
1997AIPC..385..137K Altcode: 1997recs.conf..137K
We discuss both the origin and the role that eclipse WL-polar plumes
could have in the context of the coronal hole physics: densities,
temperatures and flows. Some new results coming from the campaigns of
the 1994 and 95 eclipses are reported and YOHKOH data are also taken
into account.
---------------------------------------------------------
Title: Statistical Analysis of a Bright Point Observed Simultaneously
in Two Chromospheric and Transition Region Lines by SUMER
Authors: Bocchialini, K.; Vial, J. -C.; Einaudi, G.
1997ESASP.404..211B Altcode: 1997cswn.conf..211B
No abstract at ADS
---------------------------------------------------------
Title: Low Transition-Region Characteristics of Equatorial Coronal
Holes
Authors: Patsourakos, S.; Bocchialini, K.; Vial, J. -C.
1997ESASP.404..577P Altcode: 1997cswn.conf..577P
No abstract at ADS
---------------------------------------------------------
Title: Diagnostic and observations of quiescent and
Authors: Vial, J. -C.; Gontikakis, C.; Bocchialini, K.; Gouttebroze, P.
1997IAUJD..19E..55V Altcode:
We present a new diagnostic tool for investigating the plasma conditions
in a moving structure in the solar corona, such as an eruptive filament
or prominence. It relies on NLTE radiative transfer calculations and
the signatures of outward directed velocities on Lyman and Balmer lines
profiles. Preliminary observations with SUMER on SOHO are discussed.
---------------------------------------------------------
Title: Microwave and UV observations of filaments with SOHO and
the VLA
Authors: Alissandrakis, C. E.; Drago, F.; Bastian, T.; Bocchialini,
K.; Delaboudiniere, J. -P.; Lemaire, P.; Vial, J. -C.; Harrison,
R. A.; Thompson, B.
1997ASPC..118..289A Altcode: 1997fasp.conf..289A
Observations performed in coordination between SOHO instruments and
ground-based observatories offer the unique possibility to derive
information simultaneously in several wavelengths formed at different
altitudes and/or temperatures in the solar atmosphere. The SUMER and
CDS spectrometers, the imaging telescope EIT aboard SOHO, and the VLA
provide complementary information in the UV and the radio ranges. We
illustrate such a coordination with observations of filaments in the
transition region, performed in July 1996. The observations in the UV
between 10(4) and 10(6) K provide the differential emission measure
as a function of temperature; this can be used to compute the expected
brightness temperature in the microwave range and check models of the
filament-corona transition region.
---------------------------------------------------------
Title: First Results of SOHO's Joint Observing Programme 40
Authors: Patsourakos, S.; Bocchialini, K.; Vial, J. -C.
1997IAUJD..19E..38P Altcode:
The first results of SOHO's JOP 40 are presented. This program
proposes to study the chromospheric to transition region of equatorial
coronal holes in order to derive parameters such as the temperature,
the density, using different lines formed at different altitudes,
in different places: the boundary of a coronal hole or the central
region, on the disk. The two components of the chromospheric quiet
Sun, network and internetwork, should be observed, in and out of an
equatorial coronal hole.
---------------------------------------------------------
Title: High frequency magneto-acoustic waves in the chromosphere
Authors: Bocchialini, Karine; Koutchmy, Serge
1997AIPC..385..153B Altcode: 1997recs.conf..153B
From a time series taken over the disk center network and cell
elements in different chromospheric and photospheric lines, we discuss
the possible detection of wave-trains corresponding to frequencies
higher than the 7 mHz frequency of the familiar chromospheric 3 mn
oscillations. Their analysis would greatly benefit from observations
taken with an improved spatial resolution, free of seeing effects
which limit the precision in ground-based measurements.
---------------------------------------------------------
Title: Propagating magneto-acoustic waves in the solar chromosphere.
Authors: Baudin, F.; Bocchialini, K.; Koutchmy, S.
1996A&A...314L...9B Altcode:
We report on spectroscopic one dimensional observations showing for
the first time upward propagating 5mn period waves, which emerge from
the deep chromospheric network. Wavetrains are well measured at the
height where the He I line (at A=1083nm) is formed by the coronal
back radiation. We also present results from a time series of narrow
filtergrams of a quiet region at the disk center. The two dimensional
mapping of the power of waves observed in the chrormosphere shows the
familiar cell-like distribution corresponding to the network magnetic
field pattern. In addition, Fourier components with significantly
longer periods than 5mn were detected in the chromospheric network. We
suggest that the waves propagating in the open corona are reminescent
of photospheric oscillations transmitted by the magnetic field of the
chromospheric network.
---------------------------------------------------------
Title: High-Chromosphere and Low-Transition-Region Network: a
Different Organization in an Equatorial Coronal Hole?
Authors: Bocchialini, K.; Vial, J. -C.
1996SoPh..168...37B Altcode:
In order to investigate the high chromosphere and the low transition
region in a coronal hole, we have analysed Ca II, Mg II and hydrogen
resonance lines, recorded by the OSO-8 spectrometer in 1975. We
present the comparison between average profiles observed in and out
of the equatorial coronal hole which was at the center of the solar
disk between 27 and 29 November, 1975. We separate internetwork and
quiet-Sun (network+internetwork) profiles: for the internetwork, we
observe that the hydrogen and Mg II profiles recorded in the hole are
stronger than the profiles recorded out of the hole; a similar result,
but with a much lower contrast, is found for the quiet Sun. We discuss
this surprising result.
---------------------------------------------------------
Title: Solar chromospheric structures as observed simultaneously in
strong UV lines. II. Network and cell modelling.
Authors: Bocchialini, K.; Gouttebroze, P.
1996A&A...313..949B Altcode:
Mean line profiles of the quiet Sun spectrum, recorded simultaneously
in Lα, Lβ, Ca II H and K, and Mg II h and k lines with the OSO-8/LPSP
spectrometer were derived for structures such as supergranulation cell
and network. We compare these observed profiles with theoretical ones
computed by Vernazza et al. (1981, VAL81) and by Fontenla et al. (1993,
FAL93). We also present our own theoretical profiles : with our non-LTE
radiative transfer codes, we compute the line profiles corresponding
to different atmospheric models, derived from the reference VAL and FAL
models. Finally, we propose two new semi-empirical models, NET and CEL,
which are in better agreement with the network and cell line profiles
observed by OSO-8.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Solar chromospheric
structures. II. (Bocchialini+, 1996)
Authors: Bocchialini, K.; Gouttebroze, P.
1996yCat..33130949B Altcode:
Mean line profiles of the quiet Sun spectrum, recorded simultaneously
in Lα, Lβ, Ca II H and K, and Mg II h and k lines with the OSO-8/LPSP
spectrometer were derived for structures such as supergranulation cell
and network. We compare these observed profiles with theoretical ones
computed by Vernazza et al. (1981, VAL81) and by Fontenla et al. (1993,
FAL93). We also present our own theoretical profiles : with our non-LTE
radiative transfer codes, we compute the line profiles corresponding
to different atmospheric models, derived from the reference VAL and FAL
models. Finally, we propose two new semi-empirical models, NET and CEL,
which are in better agreement with the network and cell line profiles
observed by OSO-8. (2 data files).
---------------------------------------------------------
Title: Analyse de raies de la chromosphère solaire: diagnostic
et dynamique.
Authors: Bocchialini, K.
1995JAF....49Q..52B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Wavelet analysis of chromospheric solar oscillations.
Authors: Bocchialini, K.; Baudin, F.
1995A&A...299..893B Altcode:
We obtain new information on chromospheric oscillations from the
application of wavelet analysis to observations of the quiet Sun in
He I and Ca II lines. Using this analysing technique the temporal
behaviour of oscillations at different frequencies is illustrated in
two regions: a magnetic element network and a non magnetic intra-network
cell. The results presented below show the duration of the chromospheric
wavetrains and the correlation between the two lines, and also include
a study of the lags between the signals.
---------------------------------------------------------
Title: Chromospheric Oscillations from Simultaneous Sequences of
HEL 1083 and Call K 393.4 Spectroscopic Measurements
Authors: Bocchialini, K.; Koutchmy, S.
1995ESASP.376b.499B Altcode: 1995help.confP.499B; 1995soho....2..499B
No abstract at ADS
---------------------------------------------------------
Title: Wave Properties of the Chromosphere in He I 1083 nm and CA II K
Authors: Bocchialini, K.; Baudin, F.; Koutchmy, S.
1995itsa.conf..423B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar chromospheric structures as observed simultaneously
in strong UV lines I. Observations, statistical analysis and
characteristic line profiles.
Authors: Bocchialini, K.; Vial, J. -C.
1994A&A...287..233B Altcode:
We present a set of high resolution profiles of H Lyman α and β, Mg II
h and k, Ca II H and K lines measured near the center of the solar disk
and simultaneously above different solar chromospheric structures. The
large data base provides a way of correlating different parameters in
the different lines: correlations such as Lα reversal vs intensity,
Lα vs Ca K are discussed. We notice that Mg II and Ca II have a similar
behaviour, different from Lα and β. We also discuss a classification
derived from the distribution of integrated intensities in Ca II K,
from which average profiles (for cell, network, plage) are computed
for the six lines and are compared with theoretical ones derived from
several models.
---------------------------------------------------------
Title: Dynamical Properties of the Chromosphere In and Out of the
Solar Magnetic Network
Authors: Bocchialini, Karine; Vial, Jean-Claude; Koutchmy, Serge
1994ApJ...423L..67B Altcode:
We present the results of a comparative analysis of an 83 minute
time sequence of spectra taken around the Ca II and He I 1083 lines,
near the center of the solar disk and away from active regions. We
discuss the behavior of the Fourier spectra at low frequency: 3
minute oscillations are well observed out of the network, and 5 minute
oscillation waves are prominent in the network. The 5 s sampling time
also permits the observation of the high-frequency part of the Fourier
spectra of intensity and velocity fluctuations at different heights. At
high frequencies, K<SUB>2V</SUB>-K<SUB>2R</SUB> and 1083 (velocity)
results differ when magnetic and non-magnetic regions are compared.
---------------------------------------------------------
Title: Wave Properties in the Upper Chromosphere and at the Base of
the Corona
Authors: Bocchialini, K.; Vial, J. -C.; Koutchmy, S.
1994scs..conf..123B Altcode: 1994IAUCo.144..123B
From a 83 min long sequence of observations of Ca II K and He I (1083
nm) line profiles, some dynamical properties of the main components
of the quiet upper chromosphere are derived: for both the magnetic
network and the internetwork, amplitude and phase spectra of the
Doppler velocities are presented.
---------------------------------------------------------
Title: Analysis of Chromospheric Proxies of Coronal Bright Points
Authors: Bocchialini, K.; Vial, J. -C.; Koutchmy, S.; Zirker, J. B.
1994ASPC...68..389B Altcode: 1994sare.conf..389B
No abstract at ADS
---------------------------------------------------------
Title: Observed Chromospheric Profiles Compared with Theoretical Ones
Authors: Bocchialini, K.; Gouttebroze, P.; Vial, J. -C.
1994emsp.conf...49B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Analysis of the Chromospheric Proxies of Coronal Bright Points
- Preliminary Results
Authors: Bocchialini, K.; Koutchmy, S.; Vial, J. -C.; Zirker, J. B.
1994emsp.conf..173B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Quiet and active solar structures as observed at the bottom
of the transition region.
Authors: Bocchialini, K.; Vial, Jean-Claude
1992ESASP.348..197B Altcode: 1992cscl.work..197B
The authors present a set of high resolution profiles of H Lyman α
and β, Mg II h and k, Ca II H and K lines measured simultaneously
above different solar structures. The large data base provides a
way of correlating different parameters in the different lines:
Lα reversal vs intensity, Lα vs Ca K, etc... The authors notice
that Mg II and Ca II have a similar behaviour, different from Lα
and β ones. They also discuss two classifications derived from the
distribution of intensities, from which average (cell, network, plage,
sunspot) profiles are computed for the 6 lines. They compare the Ca
K results with the two-dimensional models of Solanki et al. (1991).
