Author name code: vial ADS astronomy entries on 2022-09-14 author:"Vial, Jean-Claude" ------------------------------------------------------------------------ Title: Linking Small-scale Solar Wind Properties with Large-scale Coronal Source Regions through Joint Parker Solar Probe-Metis/Solar Orbiter Observations Authors: Telloni, Daniele; Zank, Gary P.; Sorriso-Valvo, Luca; D'Amicis, Raffaella; Panasenco, Olga; Susino, Roberto; Bruno, Roberto; Perrone, Denise; Adhikari, Laxman; Liang, Haoming; Nakanotani, Masaru; Zhao, Lingling; Hadid, Lina Z.; Sánchez-Cano, Beatriz; Verscharen, Daniel; Velli, Marco; Grimani, Catia; Marino, Raffaele; Carbone, Francesco; Mancuso, Salvatore; Biondo, Ruggero; Pagano, Paolo; Reale, Fabio; Bale, Stuart D.; Kasper, Justin C.; Case, Anthony W.; de Wit, Thierry Dudok; Goetz, Keith; Harvey, Peter R.; Korreck, Kelly E.; Larson, Davin; Livi, Roberto; MacDowall, Robert J.; Malaspina, David M.; Pulupa, Marc; Stevens, Michael L.; Whittlesey, Phyllis; Romoli, Marco; Andretta, Vincenzo; Deppo, Vania Da; Fineschi, Silvano; Heinzel, Petr; Moses, John D.; Naletto, Giampiero; Nicolini, Gianalfredo; Spadaro, Daniele; Stangalini, Marco; Teriaca, Luca; Capobianco, Gerardo; Capuano, Giuseppe E.; Casini, Chiara; Casti, Marta; Chioetto, Paolo; Corso, Alain J.; Leo, Yara De; Fabi, Michele; Frassati, Federica; Frassetto, Fabio; Giordano, Silvio; Guglielmino, Salvo L.; Jerse, Giovanna; Landini, Federico; Liberatore, Alessandro; Magli, Enrico; Massone, Giuseppe; Messerotti, Mauro; Pancrazzi, Maurizio; Pelizzo, Maria G.; Romano, Paolo; Sasso, Clementina; Schühle, Udo; Slemer, Alessandra; Straus, Thomas; Uslenghi, Michela; Volpicelli, Cosimo A.; Zangrilli, Luca; Zuppella, Paola; Abbo, Lucia; Auchère, Frédéric; Cuadrado, Regina Aznar; Berlicki, Arkadiusz; Ciaravella, Angela; Lamy, Philippe; Lanzafame, Alessandro; Malvezzi, Marco; Nicolosi, Piergiorgio; Nisticò, Giuseppe; Peter, Hardi; Solanki, Sami K.; Strachan, Leonard; Tsinganos, Kanaris; Ventura, Rita; Vial, Jean-Claude; Woch, Joachim; Zimbardo, Gaetano Bibcode: 2022ApJ...935..112T Altcode: The solar wind measured in situ by Parker Solar Probe in the very inner heliosphere is studied in combination with the remote-sensing observation of the coronal source region provided by the METIS coronagraph aboard Solar Orbiter. The coronal outflows observed near the ecliptic by Metis on 2021 January 17 at 16:30 UT, between 3.5 and 6.3 R above the eastern solar limb, can be associated with the streams sampled by PSP at 0.11 and 0.26 au from the Sun, in two time intervals almost 5 days apart. The two plasma flows come from two distinct source regions, characterized by different magnetic field polarity and intensity at the coronal base. It follows that both the global and local properties of the two streams are different. Specifically, the solar wind emanating from the stronger magnetic field region has a lower bulk flux density, as expected, and is in a state of well-developed Alfvénic turbulence, with low intermittency. This is interpreted in terms of slab turbulence in the context of nearly incompressible magnetohydrodynamics. Conversely, the highly intermittent and poorly developed turbulent behavior of the solar wind from the weaker magnetic field region is presumably due to large magnetic deflections most likely attributed to the presence of switchbacks of interchange reconnection origin. Title: Empirical relations between the intensities of Lyman lines of H and He+ 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. Bibcode: 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.
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.
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.
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.
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 first coronal mass ejection observed in both visible-light and UV H I Ly-α channels of the Metis coronagraph on board Solar Orbiter Authors: Andretta, V.; Bemporad, A.; De Leo, Y.; Jerse, G.; Landini, F.; Mierla, M.; Naletto, G.; Romoli, M.; Sasso, C.; Slemer, A.; Spadaro, D.; Susino, R.; Talpeanu, D. -C.; Telloni, D.; Teriaca, L.; Uslenghi, M.; Antonucci, E.; Auchère, F.; Berghmans, D.; Berlicki, A.; Capobianco, G.; Capuano, G. E.; Casini, C.; Casti, M.; Chioetto, P.; Da Deppo, V.; Fabi, M.; Fineschi, S.; Frassati, F.; Frassetto, F.; Giordano, S.; Grimani, C.; Heinzel, P.; Liberatore, A.; Magli, E.; Massone, G.; Messerotti, M.; Moses, D.; Nicolini, G.; Pancrazzi, M.; Pelizzo, M. -G.; Romano, P.; Schühle, U.; Stangalini, M.; Straus, Th.; Volpicelli, C. A.; Zangrilli, L.; Zuppella, P.; Abbo, L.; Aznar Cuadrado, R.; Bruno, R.; Ciaravella, A.; D'Amicis, R.; Lamy, P.; Lanzafame, A.; Malvezzi, A. M.; Nicolosi, P.; Nisticò, G.; Peter, H.; Plainaki, C.; Poletto, L.; Reale, F.; Solanki, S. K.; Strachan, L.; Tondello, G.; Tsinganos, K.; Velli, M.; Ventura, R.; Vial, J. -C.; Woch, J.; Zimbardo, G. Bibcode: 2021A&A...656L..14A Altcode: Context. The Metis coronagraph on board Solar Orbiter offers a new view of coronal mass ejections (CMEs), observing them for the first time with simultaneous images acquired with a broad-band filter in the visible-light interval and with a narrow-band filter around the H I Ly-α line at 121.567 nm, the so-called Metis UV channel.
Aims: We show the first Metis observations of a CME, obtained on 16 and 17 January 2021. The event was also observed by the EUI/FSI imager on board Solar Orbiter, as well as by other space-based coronagraphs, such as STEREO-A/COR2 and SOHO/LASCO/C2, whose images are combined here with Metis data.
Methods: Different images are analysed here to reconstruct the 3D orientation of the expanding CME flux rope using the graduated cylindrical shell model. This also allows us to identify the possible location of the source region. Measurements of the CME kinematics allow us to quantify the expected Doppler dimming in the Ly-α channel.
Results: Observations show that most CME features seen in the visible-light images are also seen in the Ly-α images, although some features in the latter channel appear more structured than their visible-light counterparts. We estimated the expansion velocity of this event to be below 140 km s−1. Hence, these observations can be understood by assuming that Doppler dimming effects do not strongly reduce the Ly-α emission from the CME. These velocities are comparable with or smaller than the radial velocities inferred from the same data in a similar coronal structure on the east side of the Sun.
Conclusions: The first observations by Metis of a CME demonstrate the capability of the instrument to provide valuable and novel information on the structure and dynamics of these coronal events. Considering also its diagnostics capabilities regarding the conditions of the ambient corona, Metis promises to significantly advance our knowledge of such phenomena.

Movies are available at https://www.aanda.org Title: First light observations of the solar wind in the outer corona with the Metis coronagraph Authors: Romoli, M.; Antonucci, E.; Andretta, V.; Capuano, G. E.; Da Deppo, V.; De Leo, Y.; Downs, C.; Fineschi, S.; Heinzel, P.; Landini, F.; Liberatore, A.; Naletto, G.; Nicolini, G.; Pancrazzi, M.; Sasso, C.; Spadaro, D.; Susino, R.; Telloni, D.; Teriaca, L.; Uslenghi, M.; Wang, Y. -M.; Bemporad, A.; Capobianco, G.; Casti, M.; Fabi, M.; Frassati, F.; Frassetto, F.; Giordano, S.; Grimani, C.; Jerse, G.; Magli, E.; Massone, G.; Messerotti, M.; Moses, D.; Pelizzo, M. -G.; Romano, P.; Schühle, U.; Slemer, A.; Stangalini, M.; Straus, T.; Volpicelli, C. A.; Zangrilli, L.; Zuppella, P.; Abbo, L.; Auchère, F.; Aznar Cuadrado, R.; Berlicki, A.; Bruno, R.; Ciaravella, A.; D'Amicis, R.; Lamy, P.; Lanzafame, A.; Malvezzi, A. M.; Nicolosi, P.; Nisticò, G.; Peter, H.; Plainaki, C.; Poletto, L.; Reale, F.; Solanki, S. K.; Strachan, L.; Tondello, G.; Tsinganos, K.; Velli, M.; Ventura, R.; Vial, J. -C.; Woch, J.; Zimbardo, G. Bibcode: 2021A&A...656A..32R Altcode: 2021arXiv210613344R In this work, we present an investigation of the wind in the solar corona that has been initiated by observations of the resonantly scattered ultraviolet emission of the coronal plasma obtained with UVCS-SOHO, designed to measure the wind outflow speed by applying Doppler dimming diagnostics. Metis on Solar Orbiter complements the UVCS spectroscopic observations that were performed during solar activity cycle 23 by simultaneously imaging the polarized visible light and the H I Lyman-α corona in order to obtain high spatial and temporal resolution maps of the outward velocity of the continuously expanding solar atmosphere. The Metis observations, taken on May 15, 2020, provide the first H I Lyman-α images of the extended corona and the first instantaneous map of the speed of the coronal plasma outflows during the minimum of solar activity and allow us to identify the layer where the slow wind flow is observed. The polarized visible light (580-640 nm) and the ultraviolet H I Lyα (121.6 nm) coronal emissions, obtained with the two Metis channels, were combined in order to measure the dimming of the UV emission relative to a static corona. This effect is caused by the outward motion of the coronal plasma along the direction of incidence of the chromospheric photons on the coronal neutral hydrogen. The plasma outflow velocity was then derived as a function of the measured Doppler dimming. The static corona UV emission was simulated on the basis of the plasma electron density inferred from the polarized visible light. This study leads to the identification, in the velocity maps of the solar corona, of the high-density layer about ±10° wide, centered on the extension of a quiet equatorial streamer present at the east limb - the coronal origin of the heliospheric current sheet - where the slowest wind flows at about 160 ± 18 km s−1 from 4 R to 6 R. Beyond the boundaries of the high-density layer, the wind velocity rapidly increases, marking the transition between slow and fast wind in the corona. Title: High-resolution observations of prominence plume formation with the new vacuum solar telescope Authors: Xue, Jian-Chao; Vial, Jean-Claude; Su, Yang; Li, Hui; Xu, Zhi; Su, Ying-Na; Zhou, Tuan-Hui; Li, Zhen-Tong Bibcode: 2021RAA....21..222X Altcode: Prominence plumes are evacuated upflows that emerge from bubbles below prominences, whose formation mechanism is still unclear. Here we present a detailed study of plumes in a quiescent prominence using the high-resolution Hα filtergrams at the line center as well as line wing at ± 0.4 Å from the New Vacuum Solar Telescope. Enhancements of brightening, blue shifts, and turbulence at the fronts of plumes are found during their formation. Some large plumes split at their heads and finger-shaped structures are formed between them. Blue-shifted flows along the bubble-prominence interface are found before and during the plume formation. Our observations are consistent with the hypothesis that prominence plumes are related to coupled Kelvin-Helmholtz and Rayleigh-Taylor (KH/RT) instabilities. Plume splittings and fingers are evidence of RT instability, and the flows may increase the growth rate of KH/RT instabilities. However, the significant turbulence at plume fronts may suggest that the RT instability is triggered by the plumes penetrating into the prominence. In this scenario, extra mechanisms are necessary to drive the plumes. Title: White-light Continuum Observation of the Off-limb Loops of the SOL2017-09-10 X8.2 Flare: Temporal and Spatial Variations Authors: Zhao, Junwei; Liu, Wei; Vial, Jean-Claude Bibcode: 2021ApJ...921L..26Z Altcode: 2021arXiv211014130Z Observations of the Sun's off-limb white-light (WL) flares offer rare opportunities to study the energy release and transport mechanisms in flare loops. One of the best such events was SOL2017-09-10, an X8.2 flare that occurred near the Sun's west limb on 2017 September 10 and produced a WL loop system lasting more than 60 minutes and reaching an altitude higher than 30 Mm. The event was well observed by a suite of ground- and space-based instruments, including the Solar Dynamics Observatory/Helioseismic and Magnetic Imager (SDO/HMI) that captured its off-limb loops in WL continuum near Fe I 6173 Å, and the Atmospheric Imager Assembly (SDO/AIA) that observed its ultraviolet (UV) and extreme-ultraviolet (EUV) counterparts. We found quasi-periodic pulsations in the WL and UV emissions at the flare loop-top with a period around 8.0 minutes. Each pulsation appears to have an EUV counterpart that occurs earlier in time and higher in altitude. Despite many similarities in the WL and UV images and light curves, the WL flux at the loop-top continues to grow for about 16 minutes while the UV fluxes gradually decay. We discuss the implication of these unprecedented observations on the understanding of the enigmatic off-limb WL flare emission mechanisms. Title: High-Resolution Observations of Prominence Plume Formation with the New Vacuum Solar Telescope Authors: Xue, Jianchao; Vial, Jean-Claude; Li, Hui; Xu, Zhi; Su, Yang; Su, Yingna Bibcode: 2021cosp...43E.972X Altcode: 2021arXiv210501293X Prominence plumes are evacuated upflows that emerge from bubbles below prominences, whose formation mechanism is still unclear. Here we present a detailed study of plumes in a quiescent prominence using the high--resolution H$\alpha$ spectral images from the New Vacuum Solar Telescope (NVST). Enhancements of brightening, blue shifts, and turbulence at the fronts of plumes are found during their formation. Some large plumes split at their heads and finger-shaped structures (type--I) are formed between them. At the late phases of the plumes, (type--II) fingers appear along the plume boundary where flows are strong. We found the flows along the prominence boundary occur before the plume formation. Our observations are consistent with the hypothesis that prominence plumes are related to coupled Kelvin--Helmholtz and Rayleigh--Taylor (KH/RT) instabilities. Plume splits and fingers are evidence of RT instability, and the flows along prominence boundary may increase the growth rate of KH/RT instabilities. A difference from previous explanation is that the RT instability is probably triggered by the plumes penetrating into the prominence. The significant turbulence at plume fronts is likely due to the collision between plumes and the prominence, and the fingers probably result from the KH/RT instabilities at the boundary of plumes and the prominence or the flows. Other causes of the plumes are discussed, including possible contribution of spicules underneath the prominence. Title: Multiwavelength quiescent prominence spectroscopic observations Authors: Zhang, Ping; Vial, Jean-Claude; Feng, Li; Curdt, Werner; Zapior, Maciej Bibcode: 2021cosp...43E1770Z Altcode: In the frame of the SUMER-IRIS HOP 334 campaign in March-April 2017, joint prominence observations have been performed with IRIS (Mg II h and k), SUMER (L-alpha) and HSFA2 ( Ondřejov Observatory) in Ca II K, H-beta and H-alpha. We proceeded first with the difficult task of coalignment i.e. identifying the pixels of the different slits corresponding to the same solar region observed at the same time. The selected profiles photometrically calibrated have been found non-reversed.Through the use of the NLTE radiative transfer code PRODOP available at MEDOC/IAS, we tentatively derive the 1D model fitting all observed profiles. The observed Lalpha profile found to be larger than the isothermal modelled one requires the addition of a PCTR. Some basic thermodynamical parameters are consequently derived. Title: Observations of Solar Spicules at Millimeter and Ultraviolet Wavelengths Authors: Bastian, T.; De Pontieu, B.; Shimojo, M.; Iwai, K.; Alissandrakis, C.; Nindos, A.; Vial, J. C.; White, S. M. Bibcode: 2020AGUFMSH004..08B Altcode: Solar spicules are a ubiquitous chromospheric phenomenon in which multitudes of dynamic jets with temperatures of order 104 K extend thousands of kilometers into the solar atmosphere. Recent progress has been made refining the observational characteristics of spicules using the Hinode Solar Optical Telescope (SOT) and the Interface Region Imaging Spectrograph (IRIS) observations at optical and ultraviolet wavelengths, respectively. Two types of spicule have been identified. Type I spicules, prevalent in solar active regions, have upward speeds of order 25 km/s and lifetimes of 3-7 min. They may be the limb counterpart to shock-wave-driven fibrils commonly seen against the solar disk in active regions. In contrast, type II spicules, more common in quiet regions and coronal holes, display upward speeds of 50-150 km/s, lifetimes of 30-110 s, and appear to be partially heated to temperatures of 105 K and higher. These observations have provoked intense interest in spicules and have led to proposals that type II spicules play a central role as a source of hot plasma in the corona. Nevertheless, their role in mass and energy transport between the lower and upper layers of the solar atmosphere remains an outstanding problem.

Here, we report imaging observations of solar spicules at millimeter wavelengths using the Atacama Large Millimeter-submillimeter Array (ALMA) with arcsecond angular resolution. Continuum millimeter wavelength radiation forms under conditions of local thermodynamic equilibrium, thereby providing a complementary tool to UV lines, which form under non-LTE conditions. The observations were made on 2018 December 24-25 at λ=1.25 mm and λ=3 mm. The ALMA observations pose special challenges, particularly at 1.25 mm, where the limited field of view of the instrument motivated us to use a novel mosaic imaging technique: multiple pointings were assembled to form a single map with an angular resolution of 1" x 0.7" on a cadence of roughly 2 min. In contrast, we were able to image at 3 mm continuously, with a map cadence of 2 s and an angular resolution of 2.3" x 1.3".

We compare and contrast the morphology and dynamics of mm-λ observations of spicules with those obtained by IRIS at UV wavelengths and place constraints on spicule temperatures and masses using the joint millimeter-wavelength observations. Title: First results from combined EUI and SPICE observations of Lyman lines of Hydrogen and He II Authors: Teriaca, L.; Aznar Cuadrado, R.; Giunta, A. S.; Grundy, T.; Parenti, S.; Auchere, F.; Vial, J. C.; Fludra, A.; Berghmans, D.; Carlsson, M.; Harra, L.; Hassler, D.; Long, D.; Peter, H.; Rochus, P. L.; Schühle, U.; Buchlin, E.; Caldwell, M.; Caminade, S.; DeForest, C.; Fredvik, T.; Gissot, S.; Heerlein, K.; Janvier, M.; Kraaikamp, E.; Kucera, T. A.; Mueller, D.; Schmutz, W. K.; Sidher, S.; Smith, P.; Stegen, K.; Thompson, W. T.; Verbeeck, C.; Williams, D.; Young, P. R. Bibcode: 2020AGUFMSH0360003T Altcode: The Solar Orbiter spacecraft carries a powerful set of remote sensing instruments that allow studying the solar atmosphere with unprecedented diagnostic capabilities. Many such diagnostics require the simultaneous usage of more than one instrument. One example of that is the capability, for the first time, to obtain (near) simultaneous spatially resolved observations of the emission from the first three lines of the Lyman series of hydrogen and of He II Lyman alpha. In fact, the SPectral Imaging of the Coronal Environment (SPICE) spectrometer can observe the Lyman beta and gamma lines in its long wavelength (SPICE-LW) channel, the High Resolution Lyman Alpha (HRI-LYA) telescope of the Extreme Ultraviolet Imager (EUI) acquires narrow band images in the Lyman alpha line while the Full Disk Imager (FSI) of EUI can take images dominated by the Lyman alpha line of ionized Helium at 30.4 nm (FSI-304). Being hydrogen and helium the main components of our star, these very bright transitions play an important role in the energy budget of the outer atmosphere via radiative losses and the measurement of their profiles and radiance ratios is a fundamental constraint to any comprehensive modelization effort of the upper solar chromosphere and transition region. Additionally, monitoring their average ratios can serve as a check out for the relative radiometric performance of the two instruments throughout the mission. Although the engineering data acquired so far are far from ideal in terms of time simultaneity (often only within about 1 h) and line coverage (often only Lyman beta was acquired by SPICE and not always near simultaneous images from all three telescopes are available) the analysis we present here still offers a great opportunity to have a first look at the potential of this diagnostic from the two instruments. In fact, we have identified a series of datasets obtained at disk center and at various positions at the solar limb that allow studying the Lyman alpha to beta radiance ratio and their relation to He II 30.4 as a function of the position on the Sun (disk center versus limb and quiet Sun versus coronal holes). 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. Bibcode: 2020A&A...642A..14S Altcode: 2019arXiv190901183A; 2019arXiv190901183S
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.
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.
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.
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: The Solar Orbiter EUI instrument: The Extreme Ultraviolet Imager Authors: Rochus, P.; Auchère, F.; Berghmans, D.; Harra, L.; Schmutz, W.; Schühle, U.; Addison, P.; Appourchaux, T.; Aznar Cuadrado, R.; Baker, D.; Barbay, J.; Bates, D.; BenMoussa, A.; Bergmann, M.; Beurthe, C.; Borgo, B.; Bonte, K.; Bouzit, M.; Bradley, L.; Büchel, V.; Buchlin, E.; Büchner, J.; Cabé, F.; Cadiergues, L.; Chaigneau, M.; Chares, B.; Choque Cortez, C.; Coker, P.; Condamin, M.; Coumar, S.; Curdt, W.; Cutler, J.; Davies, D.; Davison, G.; Defise, J. -M.; Del Zanna, G.; Delmotte, F.; Delouille, V.; Dolla, L.; Dumesnil, C.; Dürig, F.; Enge, R.; François, S.; Fourmond, J. -J.; Gillis, J. -M.; Giordanengo, B.; Gissot, S.; Green, L. M.; Guerreiro, N.; Guilbaud, A.; Gyo, M.; Haberreiter, M.; Hafiz, A.; Hailey, M.; Halain, J. -P.; Hansotte, J.; Hecquet, C.; Heerlein, K.; Hellin, M. -L.; Hemsley, S.; Hermans, A.; Hervier, V.; Hochedez, J. -F.; Houbrechts, Y.; Ihsan, K.; Jacques, L.; Jérôme, A.; Jones, J.; Kahle, M.; Kennedy, T.; Klaproth, M.; Kolleck, M.; Koller, S.; Kotsialos, E.; Kraaikamp, E.; Langer, P.; Lawrenson, A.; Le Clech', J. -C.; Lenaerts, C.; Liebecq, S.; Linder, D.; Long, D. M.; Mampaey, B.; Markiewicz-Innes, D.; Marquet, B.; Marsch, E.; Matthews, S.; Mazy, E.; Mazzoli, A.; Meining, S.; Meltchakov, E.; Mercier, R.; Meyer, S.; Monecke, M.; Monfort, F.; Morinaud, G.; Moron, F.; Mountney, L.; Müller, R.; Nicula, B.; Parenti, S.; Peter, H.; Pfiffner, D.; Philippon, A.; Phillips, I.; Plesseria, J. -Y.; Pylyser, E.; Rabecki, F.; Ravet-Krill, M. -F.; Rebellato, J.; Renotte, E.; Rodriguez, L.; Roose, S.; Rosin, J.; Rossi, L.; Roth, P.; Rouesnel, F.; Roulliay, M.; Rousseau, A.; Ruane, K.; Scanlan, J.; Schlatter, P.; Seaton, D. B.; Silliman, K.; Smit, S.; Smith, P. J.; Solanki, S. K.; Spescha, M.; Spencer, A.; Stegen, K.; Stockman, Y.; Szwec, N.; Tamiatto, C.; Tandy, J.; Teriaca, L.; Theobald, C.; Tychon, I.; van Driel-Gesztelyi, L.; Verbeeck, C.; Vial, J. -C.; Werner, S.; West, M. J.; Westwood, D.; Wiegelmann, T.; Willis, G.; Winter, B.; Zerr, A.; Zhang, X.; Zhukov, A. N. Bibcode: 2020A&A...642A...8R Altcode: Context. The Extreme Ultraviolet Imager (EUI) is part of the remote sensing instrument package of the ESA/NASA Solar Orbiter mission that will explore the inner heliosphere and observe the Sun from vantage points close to the Sun and out of the ecliptic. Solar Orbiter will advance the "connection science" between solar activity and the heliosphere.
Aims: With EUI we aim to improve our understanding of the structure and dynamics of the solar atmosphere, globally as well as at high resolution, and from high solar latitude perspectives.
Methods: The EUI consists of three telescopes, the Full Sun Imager and two High Resolution Imagers, which are optimised to image in Lyman-α and EUV (17.4 nm, 30.4 nm) to provide a coverage from chromosphere up to corona. The EUI is designed to cope with the strong constraints imposed by the Solar Orbiter mission characteristics. Limited telemetry availability is compensated by state-of-the-art image compression, onboard image processing, and event selection. The imposed power limitations and potentially harsh radiation environment necessitate the use of novel CMOS sensors. As the unobstructed field of view of the telescopes needs to protrude through the spacecraft's heat shield, the apertures have been kept as small as possible, without compromising optical performance. This led to a systematic effort to optimise the throughput of every optical element and the reduction of noise levels in the sensor.
Results: In this paper we review the design of the two elements of the EUI instrument: the Optical Bench System and the Common Electronic Box. Particular attention is also given to the onboard software, the intended operations, the ground software, and the foreseen data products.
Conclusions: The EUI will bring unique science opportunities thanks to its specific design, its viewpoint, and to the planned synergies with the other Solar Orbiter instruments. In particular, we highlight science opportunities brought by the out-of-ecliptic vantage point of the solar poles, the high-resolution imaging of the high chromosphere and corona, and the connection to the outer corona as observed by coronagraphs. Title: Metis: the Solar Orbiter visible light and ultraviolet coronal imager Authors: Antonucci, Ester; Romoli, Marco; Andretta, Vincenzo; Fineschi, Silvano; Heinzel, Petr; Moses, J. Daniel; Naletto, Giampiero; Nicolini, Gianalfredo; Spadaro, Daniele; Teriaca, Luca; Berlicki, Arkadiusz; Capobianco, Gerardo; Crescenzio, Giuseppe; Da Deppo, Vania; Focardi, Mauro; Frassetto, Fabio; Heerlein, Klaus; Landini, Federico; Magli, Enrico; Marco Malvezzi, Andrea; Massone, Giuseppe; Melich, Radek; Nicolosi, Piergiorgio; Noci, Giancarlo; Pancrazzi, Maurizio; Pelizzo, Maria G.; Poletto, Luca; Sasso, Clementina; Schühle, Udo; Solanki, Sami K.; Strachan, Leonard; Susino, Roberto; Tondello, Giuseppe; Uslenghi, Michela; Woch, Joachim; Abbo, Lucia; Bemporad, Alessandro; Casti, Marta; Dolei, Sergio; Grimani, Catia; Messerotti, Mauro; Ricci, Marco; Straus, Thomas; Telloni, Daniele; Zuppella, Paola; Auchère, Frederic; Bruno, Roberto; Ciaravella, Angela; Corso, Alain J.; Alvarez Copano, Miguel; Aznar Cuadrado, Regina; D'Amicis, Raffaella; Enge, Reiner; Gravina, Alessio; Jejčič, Sonja; Lamy, Philippe; Lanzafame, Alessandro; Meierdierks, Thimo; Papagiannaki, Ioanna; Peter, Hardi; Fernandez Rico, German; Giday Sertsu, Mewael; Staub, Jan; Tsinganos, Kanaris; Velli, Marco; Ventura, Rita; Verroi, Enrico; Vial, Jean-Claude; Vives, Sebastien; Volpicelli, Antonio; Werner, Stephan; Zerr, Andreas; Negri, Barbara; Castronuovo, Marco; Gabrielli, Alessandro; Bertacin, Roberto; Carpentiero, Rita; Natalucci, Silvia; Marliani, Filippo; Cesa, Marco; Laget, Philippe; Morea, Danilo; Pieraccini, Stefano; Radaelli, Paolo; Sandri, Paolo; Sarra, Paolo; Cesare, Stefano; Del Forno, Felice; Massa, Ernesto; Montabone, Mauro; Mottini, Sergio; Quattropani, Daniele; Schillaci, Tiziano; Boccardo, Roberto; Brando, Rosario; Pandi, Arianna; Baietto, Cristian; Bertone, Riccardo; Alvarez-Herrero, Alberto; García Parejo, Pilar; Cebollero, María; Amoruso, Mauro; Centonze, Vito Bibcode: 2020A&A...642A..10A Altcode: 2019arXiv191108462A
Aims: Metis is the first solar coronagraph designed for a space mission and is capable of performing simultaneous imaging of the off-limb solar corona in both visible and UV light. The observations obtained with Metis aboard the Solar Orbiter ESA-NASA observatory will enable us to diagnose, with unprecedented temporal coverage and spatial resolution, the structures and dynamics of the full corona in a square field of view (FoV) of ±2.9° in width, with an inner circular FoV at 1.6°, thus spanning the solar atmosphere from 1.7 R to about 9 R, owing to the eccentricity of the spacecraft orbit. Due to the uniqueness of the Solar Orbiter mission profile, Metis will be able to observe the solar corona from a close (0.28 AU, at the closest perihelion) vantage point, achieving increasing out-of-ecliptic views with the increase of the orbit inclination over time. Moreover, observations near perihelion, during the phase of lower rotational velocity of the solar surface relative to the spacecraft, allow longer-term studies of the off-limb coronal features, thus finally disentangling their intrinsic evolution from effects due to solar rotation.
Methods: Thanks to a novel occultation design and a combination of a UV interference coating of the mirrors and a spectral bandpass filter, Metis images the solar corona simultaneously in the visible light band, between 580 and 640 nm, and in the UV H I Lyman-α line at 121.6 nm. The visible light channel also includes a broadband polarimeter able to observe the linearly polarised component of the K corona. The coronal images in both the UV H I Lyman-α and polarised visible light are obtained at high spatial resolution with a spatial scale down to about 2000 km and 15 000 km at perihelion, in the cases of the visible and UV light, respectively. A temporal resolution down to 1 s can be achieved when observing coronal fluctuations in visible light.
Results: The Metis measurements, obtained from different latitudes, will allow for complete characterisation of the main physical parameters and dynamics of the electron and neutral hydrogen/proton plasma components of the corona in the region where the solar wind undergoes the acceleration process and where the onset and initial propagation of coronal mass ejections (CMEs) take place. The near-Sun multi-wavelength coronal imaging performed with Metis, combined with the unique opportunities offered by the Solar Orbiter mission, can effectively address crucial issues of solar physics such as: the origin and heating/acceleration of the fast and slow solar wind streams; the origin, acceleration, and transport of the solar energetic particles; and the transient ejection of coronal mass and its evolution in the inner heliosphere, thus significantly improving our understanding of the region connecting the Sun to the heliosphere and of the processes generating and driving the solar wind and coronal mass ejections.
Conclusions: This paper presents the scientific objectives and requirements, the overall optical design of the Metis instrument, the thermo-mechanical design, and the processing and power unit; reports on the results of the campaigns dedicated to integration, alignment, and tests, and to the characterisation of the instrument performance; describes the operation concept, data handling, and software tools; and, finally, the diagnostic techniques to be applied to the data, as well as a brief description of the expected scientific products. The performance of the instrument measured during calibrations ensures that the scientific objectives of Metis can be pursued with success.

Metis website: http://metis.oato.inaf.it Title: New Light on an Old Problem of the Cores of Solar Resonance Lines Authors: Judge, Philip G.; Kleint, Lucia; Leenaarts, Jorrit; Sukhorukov, Andrii V.; Vial, Jean-Claude Bibcode: 2020ApJ...901...32J Altcode: 2020arXiv200801250J We reexamine a 50+ yr old problem of deep central reversals predicted for strong solar spectral lines, in contrast to the smaller reversals seen in observations. We examine data and calculations for the resonance lines of H I, Mg II, and Ca II, the self-reversed cores of which form in the upper chromosphere. Based on 3D simulations, as well as data for the Mg II lines from the Interface Region Imaging Spectrograph (IRIS), we argue that the resolution lies not in velocity fields on scales in either of the micro- or macroturbulent limits. Macroturbulence is ruled out using observations of optically thin lines formed in the upper chromosphere, and by showing that it would need to have unreasonably special properties to account for critical observations of the Mg II resonance lines from the IRIS mission. The power in "turbulence" in the upper chromosphere may therefore be substantially lower than earlier analyses have inferred. Instead, in 3D calculations horizontal radiative transfer produces smoother source functions, smoothing out intensity gradients in wavelength and in space. These effects increase in stronger lines. Our work will have consequences for understanding the onset of the transition region, for understanding the energy in motions available for heating the corona, and for the interpretation of polarization data in terms of the Hanle effect applied to resonance line profiles. Title: The synergy between the payloads on the ASO-S mission Authors: Vial, Jean-Claude Bibcode: 2019RAA....19..166V Altcode: This paper addresses the improved science resulting from joint observations performed by the different instruments onboard the Advanced Space-based Solar Observatory (ASO-S) mission along with ancillary instruments on missions flying at the same time. It first describes the three major instruments along with their stated objectives. Then it presents some basic science issues concerning jointly observed flares, coronal mass ejections (CMEs) and eruptive prominences (EPs). Each physical candidate (magnetic reconnection, instability, hard X-ray emission and magnetic coronal field topology) is discussed in terms of its signature and identification with ASO-S instrumentation. The importance of Lyα detection and non-LTE modeling is stressed. Some instrumental and science challenges are briefly discussed. Title: Elemental composition in quiescent prominences Authors: Parenti, S.; Del Zanna, G.; Vial, J. -C. Bibcode: 2019A&A...625A..52P Altcode: 2019arXiv190500871P Context. The first ionization potential (FIP) bias is currently used to trace the propagation of solar features ejected by the wind and solar eruptions (coronal mass ejections). The FIP bias also helps us to understand the formation of prominences, as it is a tracer for the solar origin of prominence plasma.
Aims: This work aims to provide elemental composition and FIP bias in quiescent solar prominences. This is key information to link these features to remnants of solar eruptions measured in-situ within the heliosphere and to constrain the coronal or photospheric origin of prominence plasma.
Methods: We used the differential emission measure technique to derive the FIP bias of two prominences. Quiet Sun chromospheric and transition region data were used to test the atomic data and lines formation processes. We used lines from low stage of ionization of Si, S, Fe, C, N, O, Ni, Mg, and Ne, constraining the FIP bias in the range 4.2 ≤ log T ≤ 5.8. We adopted a density-dependent ionization equilibrium.
Results: We showed that the two prominences have photospheric composition. We confirmed a photospheric composition in the quiet Sun. We also identified opacity and/or radiative excitation contributions to the line formation of a few lines regularly observed in prominences.
Conclusions: With our results we thus provide important elements for correctly interpreting the upcoming Solar Orbiter/SPICE spectroscopic data and to constrain prominence formation. Title: Elemental composition in quiescent prominences Authors: Parenti, Susanna; Del Zanna, Giulio; Vial, Jean-Claude Bibcode: 2019shin.confE.182P Altcode: The first ionization potential (FIP) bias is currently used to trace the propagation of solar features ejected by the wind and solar eruptions (coronal mass ejections). The FIP bias also helps us to understand the formation of prominences, as it is a tracer for the solar origin of prominence plasma. This work aims to provide elemental composition and FIP bias in quiescent solar prominences. This is key information to link these features to remnants of solar eruptions measured in-situ within the heliosphere and to constrain the coronal or photospheric origin of prominence plasma. We used the differential emission measure technique to derive the FIP bias of two prominences observed with SOHO/SUMER. Quiet Sun chromospheric and transition region data were used to test the atomic data and lines formation processes. We used lines from low stage of ionization of Si, S, Fe, C, N, O, Ni, Mg, and Ne, constraining the FIP bias in the range 4.2 < log T< 5.8. We adopted a density-dependent ionization equilibrium. We showed that the two prominences have photospheric composition. We also identified opacity and/or radiative excitation contributions to the line formation of a few lines regularly observed in prominences. With our results we thus provide important elements for correctly interpreting the upcoming Solar Orbiter/SPICE spectroscopic data and to constrain prominence formation. Title: Some relationships between radiative and atmospheric quantities through 1D NLTE modeling of prominences in the Mg II lines Authors: Vial, J. -C.; Zhang, P.; Buchlin, É. Bibcode: 2019A&A...624A..56V Altcode: Context. With more than four years of IRIS observations, and in order to avoid building customized diagnostics for each observation, it is useful to derive some simple relations between spectra and physical quantities. This is even more useful for the k and h lines of Mg II, which require complex non-local-thermodynamic-equilibrium NLTE treatments.
Aims: The aim of this work concerning prominences is to correlate observable spectral features in h and k lines of Mg II to physical quantities such as the density and the emission measure (EM) in the same way as similar correlations have been obtained in the hydrogen lines. In this way, and within approximations done on some parameters such as temperature, it is possible to build pixel by pixel an IRIS map of the above-mentioned quantities.
Methods: In order to simplify and shorten the modeling, we chose to compute one-dimensional (1D) isothermal and isobaric models that are treated with the PROM7 NLTE code available at MEDOC (IAS). We built a set of models with large ranges of temperature, pressure, and thickness. At all altitudes considered, we paid attention to the exact computation of the incident radiation. Then we compared the emergent Mg II h and k intensities with the corresponding hydrogen and electron densities and EMs.
Results: From the NLTE computation, we derive correlations between the k and h emergent intensities on one hand and the densities and EM on the other hand. With some assumptions on the temperature, we obtain a unique relation between the k (and h) intensities and the EM that should be useful for deriving either the hydrogen and electron densities or the effective thickness of an observed prominence.
Conclusions: From NLTE modeling, we have provided a relationship between observable integrated intensities of the Mg II resonance lines and prominence plasma EM, which will contribute to a first-order analysis of long time series of spectroscopic observations, for example, with IRIS. We anticipate building more complex relations between the profiles and other plasma quantities. Title: Launch of a CME-associated eruptive prominence as observed with IRIS and ancillary instruments Authors: Zhang, P.; Buchlin, É.; Vial, J. -C. Bibcode: 2019A&A...624A..72Z Altcode:
Aims: In this paper we focus on the possible observational signatures of the processes which have been put forward for explaining eruptive prominences. We also try to understand the variations in the physical conditions of eruptive prominences and estimate the masses leaving the Sun versus the masses returning to the Sun during eruptive prominences.
Methods: As far as velocities are concerned, we combined an optical flow method on the Atmospheric Imaging Assembly (AIA) 304 Å and Interface Region Imaging Spectrograph (IRIS). Mg II h&k observations in order to derive the plane-of-sky velocities in the prominence, and a Doppler technique on the IRIS Mg II h&k profiles to compute the line-of-sight velocities. As far as densities are concerned, we compared the absolute observed intensities with values derived from non-local thermodynamic equilibrium radiative transfer computations to derive the total (hydrogen) density and consequently compute the mass flows.
Results: The derived electron densities range from 1.3 × 109 to 6.0 × 1010 cm-3 and the derived total hydrogen densities range from 1.5 × 109 to 2.4 × 1011 cm-3 in different regions of the prominence. The mean temperature is around 1.1 × 104 K, which is higher than in quiescent prominences. The ionization degree is in the range of 0.1-10. The total (hydrogen) mass is in the range of 1.3 × 1014-3.2 × 1014 g. The total mass drainage from the prominence to the solar surface during the whole observation time of IRIS is about one order of magnitude smaller than the total mass of the prominence.

The movie associated to Fig. 2 is available at https://www.aanda.org Title: Preface Authors: Engvold, Oddbjørn; Vial, Jean-Claude; Skumanich, Andrew Bibcode: 2019sgsp.bookD..17E Altcode: No abstract at ADS Title: Chapter 14 - Challenges and Prospects for the Future Authors: Vial, Jean-Claude; Skumanich, Andrew Bibcode: 2019sgsp.book..463V Altcode: The 14 chapters (and five subchapters) of this book have addressed only a few aspects of the many works that have been produced during the latest decades in the domain of solar physics and that may be relevant to stellar physics and possibly other fields in astrophysics. The achievements result not only from the proximity of our star, which allows for detailed and comprehensive observations but also from the many questions that have arisen and have been answered through the implications of physics and sometimes have led to the stimulation of a "new" physics.

We do not include the summaries and conclusions of these 14 chapters here. We simply focus on a few points (challenges and prospects) that may be of interest for future progress and discoveries in solar and stellar physics. As is shown here, we also allow ourselves to point out that some authors of the book, including ourselves, may have some different views on a few topics, a fact of life in science. We address the various issues with the two following questions in mind: Where and how is solar progress foreseen? What are the mutual benefits in the solar-stellar connection? Title: The Sun as a Guide to Stellar Physics Authors: Engvold, Oddbjørn; Vial, Jean-Claude; Skumanich, Andrew Bibcode: 2019sgsp.book.....E Altcode: No abstract at ADS Title: Effects of resonant scattering of the Si IV doublet near 140 nm in a solar active region Authors: Gontikakis, C.; Vial, J. -C. Bibcode: 2018A&A...619A..64G Altcode:
Aims: In a previous study we analysed the C IV 1548.189 Å and 1550.775 Å lines observed with the Solar Ultraviolet Measurements of Emitted Radiation (SUMER), showing cases where the 1548.189 Å spectral profile was noticeably different from the 1550.775 Å one, profiles that we dubbed differentially shaped profiles. We explained this differential behaviour by an important radiative contribution, affecting multiple plasma motions happening at the instrument sub-resolution scale. In the present study we examine more general cases where radiative effects may contribute to the emission from the transition region of an active region. Here we analyse the lines Si IV 1393.757 Å and 1402.772 Å observed with the Interface Region Imaging Spectrograph (IRIS).
Methods: We study active region NOAA 12529, observed with IRIS on 18 April 2016. Using sorting techniques we selected individual profiles for which the intensity line ratio 1393.757 Å/1402.772 Å is significantly higher or lower than 2 and we also tracked differentially shaped profiles. We analyse the physical conditions that create these profiles and in some cases we estimate electron densities.
Results: We found more than 4000 individual profiles with line ratios higher than 2, about 500 profiles for which the line ratio is in the range 1.3-1.6, and 15 differentially shaped profiles. Line ratios higher than 2, are found along loops, and mostly at the y = 250 to 300″ part of the plage. There, we estimated the incident radiation and derived electron densities that can vary from 109 to a few times 1011 cm-3, depending on the plasma temperature. For the low line ratios, the sources are concentrated at the periphery of the active region plage, mostly along fibrils and present optical depths, τ, between 1.5 and 3. in most cases. The electron densities calculated from these Si IV profiles are comparable with electron densities derived using the O IV 1399.766 Å-1401.163 Å ratios.
Conclusions: We found that about 2.4% of the individual profiles for which we can perform a Gaussian fit present a line ratio higher than 2. In profiles with a high line ratio, the resonant scattering appears to be due to the combination of an average incident radiation field with a relatively low local electron density and not due to the vicinity of an ephemeral strong light source. As far as low intensity ratios are concerned, non-negligible optical depths are found at the edge of the plage, near the footpoints of fibrils that are oriented towards quiet Sun areas, where the electron density can be as high as (7 - 9) × 1011 cm-3 if we assume a plasma in ionization equilibrium.

The movie associated to Fig. 3 is only available at https://www.aanda.org Title: First high-resolution look at the quiet Sun with ALMA at 3mm Authors: Nindos, A.; Alissandrakis, C. E.; Bastian, T. S.; Patsourakos, S.; De Pontieu, B.; Warren, H.; Ayres, T.; Hudson, H. S.; Shimizu, T.; Vial, J. -C.; Wedemeyer, S.; Yurchyshyn, V. Bibcode: 2018A&A...619L...6N Altcode: 2018arXiv181005223N We present an overview of high-resolution quiet Sun observations, from disk center to the limb, obtained with the Atacama Large millimeter and sub-millimeter Array (ALMA) at 3 mm. Seven quiet-Sun regions were observed at a resolution of up to 2.5″ by 4.5″. We produced both average and snapshot images by self-calibrating the ALMA visibilities and combining the interferometric images with full-disk solar images. The images show well the chromospheric network, which, based on the unique segregation method we used, is brighter than the average over the fields of view of the observed regions by ∼305 K while the intranetwork is less bright by ∼280 K, with a slight decrease of the network/intranetwork contrast toward the limb. At 3 mm the network is very similar to the 1600 Å images, with somewhat larger size. We detect, for the first time, spicular structures, rising up to 15″ above the limb with a width down to the image resolution and brightness temperature of ∼1800 K above the local background. No trace of spicules, either in emission or absorption, is found on the disk. Our results highlight the potential of ALMA for the study of the quiet chromosphere. Title: Cool Material in the Hot Solar Corona and the Chromosphere-Corona Mass Cycle Authors: Liu, Wei; Vial, Jean-Claude; Antolin, Patrick; Sun, Xudong; Berger, Thomas Bibcode: 2018cosp...42E2052L Altcode: In the million-degree hot and tenuous solar corona, under favorable conditions, some mass can undergo a radiative cooling instability and condense into material of 100 times cooler in two distinct forms - prominences and coronal rain. Being at similar temperatures, they exhibit contrasting morphologies and behaviors: a quiescent prominence usually consists of numerous long-lasting, filamentary downflow threads, while coronal rain consists of transient mass blobs falling at comparably higher speeds along well-defined, curved paths (e.g., guided by coronal loops). We report recent imaging and spectroscopic observations from SDO/AIA and IRIS of a hybrid prominence-coronal rain complex structure that suggest different magnetic environments being responsible for such distinctions. We also present an ensemble of observations of the so-called funnel prominences that reside near the dips of magnetic funnels. Regardless of their morphological and behavioral differences, a large fraction of prominence and coronal rain material eventually falls back to the chromosphere and serves as the return flow of the so-called chromosphere-corona mass cycle (the other half of this cycle is the upward transport of heated mass from the chromosphere to the corona). We estimate the downflow mass fluxes in prominences and coronal rain, and compare them with the coronal mass budget in this cycle and with the mass loss to the solar wind and coronal mass ejections (CMEs). We will discuss the broad physical implications of these observations for fundamental questions, such as coronal heating and beyond. Title: An analysis of simultaneous observations of a CME-associated eruptive prominence with IRIS, AIA/SDO, EUVI/STEREO and K-COR Authors: Zhang, Ping; Vial, Jean-Claude; Buchlin, Eric Bibcode: 2018cosp...42E3836Z Altcode: We present the simultaneous observations of a CME-associated eruptive prominence which have been made by the Interface Region Imaging Spectrograph (IRIS), Atmospheric Imaging Assembly (AIA) of SDO, EUVI of STEREO and the ground-based K-COR coronagraph. IRIS observations started on 2014 May 28 at 11:25 UT, lasted for about 4.5 hours. With the aim of deriving the velocity vector, we first combined an optical flow method on the AIA 304 observations to compute the POS velocities in the prominence and a Doppler technique with the IRIS observations to compute the LOS velocities. Then we characterized the Mg h and k profiles (time and space-dependent) and compared with the signatures of various (1000) prominence models through NLTE radiative transfer computations (I.A.S. PROM7 code). We paid much attention to the exact incident radiation in various lines and continua. The model parameters include pressure, temperature, height, thickness, radial and turbulence velocities. Having selected the best (fitting) models, we were able to derive the total (hydrogen) density and compute the mass flows. We also used the STEREO observations to derive the 3D geometry of the prominence and K-COR to derive the density later on in the process of eruption. Applying this method to more prominences observed by IRIS could help to reduce the large range of thermodynamic parameters in eruptive prominences and to improve their MHD modeling. Title: Chemical fractionation in solar prominences Authors: Parenti, Susanna; Vial, Jean-Claude; Del Zanna, Giulio Bibcode: 2018cosp...42E2585P Altcode: The First Ionization Potential (FIP) fractionation of elemental abundances in the solar atmosphere and solar wind is a known process which appears to vary depending on the magnetic field property and the dynamic nature of the environment. It is generally identified by an increase of the low FIP elements (with FIP energy below 10 eV) compared to the high FIP elements (with respect to the photospheric values). For instance, the low FIP element abundance is enhanced within active regions by about a factor of 3-4, with respect to photospheric values. A similar property is measured in the slow solar wind. This is one of the reasons why the FIP fractionation is used as a proxy for identifying the solar wind source regions on the Sun, a topic of particular relevance for the upcoming Solar Orbiter mission.Cool, low-state ionized plasma and its composition have been measured in-situ within interplanetary Coronal Mass Ejections (ICMEs) in only a few cases. This cool plasma has been associated to remnants of erupting prominences. However, this association is not confirmed, because the measurement of the composition within prominence plasma is very difficult and poorly known. The scope of this paper is to provide a reliable measurement of elements composition and FIP fractionation in a prominence using the available SOHO/SUMER dataset of the prominence atlas presented in Parenti et. al 2005. Our investigation will consider ions formed in the prominence-corona transition region, taking into account possible density and opacity effects in the formation of the spectral lines. Title: Physical conditions in a prominence eruption during its pre-eruption and acceleration Authors: Zhang, Ping; Vial, Jean-Claude; Buchlin, Eric Bibcode: 2018cosp...42E3837Z Altcode: We rely upon the simultaneous observations of a CME-associated eruptive prominence which have been made by the Interface Region Imaging Spectrograph (IRIS), Atmospheric Imaging Assembly (AIA) of SDO, EUVI of STEREO and the ground-based K-COR coronagraph. We focus on the determination of mass flows in order to detect a possible mass loading. In order to derive the full velocity vector, we combine an optical flow method on the AIA 304 and IRIS SJI observations to compute the POS velocities in the prominence and a Doppler technique with the IRIS observations to compute the LOS velocities. Then we focus on the determination of densities through the combination of spectroscopic observations and NLTE modelling. We first characterize the Mg II h and k profiles (time and space-dependent!) through a grid of 6 typical profiles (reversed and unreversed). Then we compare them with the signatures of hundreds of prominence models through NLTE radiative transfer computations (I.A.S. PROM7 code). Much attention is paid to the exact incident radiation in various lines and continua. Having selected the best (fitting) models, we are able to derive the total (hydrogen) density and compute the mass flows. The derivation of physical parameters (e.g. velocity) also takes into account the STEREO observations to derive the 3D geometry of the prominence and K-COR to derive the density later on in the process of eruption. Title: IRIS Observations of Spicules and Structures Near the Solar Limb Authors: Alissandrakis, C. E.; Vial, J. -C.; Koukras, A.; Buchlin, E.; Chane-Yook, M. Bibcode: 2018SoPh..293...20A Altcode: 2018arXiv180102082A We have analyzed Interface Region Imaging Spectrograph (IRIS) spectral and slit-jaw observations of a quiet region near the South Pole. In this article we present an overview of the observations, the corrections, and the absolute calibration of the intensity. We focus on the average profiles of strong (Mg II h and k, C II and Si IV), as well as of weak spectral lines in the near ultraviolet (NUV) and the far ultraviolet (FUV), including the Mg II triplet, thus probing the solar atmosphere from the low chromosphere to the transition region. We give the radial variation of bulk spectral parameters as well as line ratios and turbulent velocities. We present measurements of the formation height in lines and in the NUV continuum from which we find a linear relationship between the position of the limb and the intensity scale height. We also find that low forming lines, such as the Mg II triplet, show no temporal variations above the limb associated with spicules, suggesting that such lines are formed in a homogeneous atmospheric layer and, possibly, that spicules are formed above the height of 2. We discuss the spatio-temporal structure of the atmosphere near the limb from images of intensity as a function of position and time. In these images, we identify p-mode oscillations in the cores of lines formed at low heights above the photosphere, slow-moving bright features in O I and fast-moving bright features in C II. Finally, we compare the Mg II k and h line profiles, together with intensity values of the Balmer lines from the literature, with computations from the PROM57Mg non-LTE model, developed at the Institut d' Astrophysique Spatiale, and estimated values of the physical parameters. We obtain electron temperatures in the range of ∼8000 K at small heights to ∼20 000 K at large heights, electron densities from 1.1 ×1011 to 4 ×1010cm−3 and a turbulent velocity of ∼24 kms−1. Title: EUV imager and spectrometer for LYOT and solar orbiter space missions Authors: Millard, Anne; Lemaire, Philippe; Vial, Jean-Claude Bibcode: 2017SPIE10568E..0RM Altcode: In the 2010 horizon, solar space missions such as LYOT and Solar Orbiter will allow high cadence UV observations of the Sun at spatial and spectral resolution never obtained before. To reach these goals, the two missions could take advantage of spectro-imagers. A reflective only optical solution for such an instrument is described in this paper and the first results of the mock-up being built at IAS are shown. Title: Definition of a metrology servo-system for a solar imaging fourier transform spectrometer working in the far UV (IFTSUV) Authors: Ruiz de Galarreta Fanju, C.; Philippon, A.; Bouzit, M.; Appourchaux, T.; Vial, J. -C.; Maillard, J. -P.; Lemaire, P. Bibcode: 2017SPIE10564E..3ER Altcode: The understanding of the solar outer atmosphere requires a simultaneous combination of imaging and spectral observations concerning the far UV lines that arise from the high chromospheres up to the corona. These observations must be performed with enough spectral, spatial and temporal resolution to reveal the small atmospheric structures and to resolve the solar dynamics. An Imaging Fourier Transform Spectrometer working in the far-UV (IFTSUV, Figure 1) is an attractive instrumental solution to fulfill these requirements. However, due to the short wavelength, to preserve IFTSUV spectral precision and Signal to Noise Ratio (SNR) requires a high optical surface quality and a very accurate (linear and angular) metrology to maintain the optical path difference (OPD) during the entire scanning process by: optical path difference sampling trigger; and dynamic alignment for tip/tilt compensation (Figure 2). Title: The Fate of Cool Material in the Hot Corona: Solar Prominences and Coronal Rain Authors: Liu, Wei; Antolin, Patrick; Sun, Xudong; Vial, Jean-Claude; Berger, Thomas Bibcode: 2017SPD....4810501L Altcode: As an important chain of the chromosphere-corona mass cycle, some of the million-degree hot coronal mass undergoes a radiative cooling instability and condenses into material at chromospheric or transition-region temperatures in two distinct forms - prominences and coronal rain (some of which eventually falls back to the chromosphere). A quiescent prominence usually consists of numerous long-lasting, filamentary downflow threads, while coronal rain consists of transient mass blobs falling at comparably higher speeds along well-defined paths. It remains puzzling why such material of similar temperatures exhibit contrasting morphologies and behaviors. We report recent SDO/AIA and IRIS observations that suggest different magnetic environments being responsible for such distinctions. Specifically, in a hybrid prominence-coronal rain complex structure, we found that the prominence material is formed and resides near magnetic null points that favor the radiative cooling process and provide possibly a high plasma-beta environment suitable for the existence of meandering prominence threads. As the cool material descends, it turns into coronal rain tied onto low-lying coronal loops in a likely low-beta environment. Such structures resemble to certain extent the so-called coronal spiders or cloud prominences, but the observations reported here provide critical new insights. We will discuss the broad physical implications of these observations for fundamental questions, such as coronal heating and beyond (e.g., in astrophysical and/or laboratory plasma environments). Title: Neutral Hydrogen and Its Emission Lines in the Solar Corona Authors: Vial, Jean-Claude; Chane-Yook, Martine Bibcode: 2016SoPh..291.3549V Altcode: 2016SoPh..tmp..184V; 2016arXiv160905092V Since the Lyman-α rocket observations of Gabriel (Solar Phys.21, 392, 1971), it has been realized that the hydrogen (H) lines could be observed in the corona and that they offer an interesting diagnostic for the temperature, density, and radial velocity of the coronal plasma. Moreover, various space missions have been proposed to measure the coronal magnetic and velocity fields through polarimetry in H lines. A necessary condition for such measurements is to benefit from a sufficient signal-to-noise ratio. The aim of this article is to evaluate the emission in three representative lines of H for three different coronal structures. The computations have been performed with a full non-local thermodynamic-equilibrium (non-LTE) code and its simplified version without radiative transfer. Since all collisional and radiative quantities (including incident ionizing and exciting radiation) are taken into account, the ionization is treated exactly. Profiles are presented at two heights (1.05 and 1.9 solar radii, from Sun center) in the corona, and the integrated intensities are computed at heights up to five solar radii. We compare our results with previous computations and observations (e.g. Lα from Ultraviolet Coronal Spectrometer) and find a rough (model-dependent) agreement. Since the Hα line is a possible candidate for ground-based polarimetry, we show that in order to detect its emission in various coronal structures, it is necessary to use a very narrow (less than 2 Å wide) bandpass filter. Title: From the Observation of Non-symmetrical Profiles of the C IV Resonance Lines for Small Dynamic Events to their Interpretation in Terms of Resonant Scattering in Solar Active Regions Authors: Vial, J. C. Bibcode: 2016AGUFMSH33A..01V Altcode: We present observations of small areas in solar active regions recorded with the SUMER/SOHO spectrograph where the C IV 1548A and 1550A lines have spectral profiles of different shapes, although they are recorded simultaneously and at the same location. We propose to explain this asymmetry by resonant scattering of strong incident radiation from close-by regions, associated with relative velocities of the emitting plasmas. We present detailed artificial spectral profiles that may explain the observations. The profiles have been computed using several physical parameters such as the plasma temperature and electron density and the incident radiation on the emitting volumes. We conclude that the study of asymmetries in the C IV 1548A, 1550A lines, and also in different doublets (e.g. Si IV for IRIS), should include this radiative interaction and moreover that it can be a valuable diagnostic tool for deriving the physical conditions in solar/stellar plasmas, especially where the radiation processes (such as flare-emission) are enhanced at the vicinity of the observed structures. Title: Probing the Physical Connection between Solar Prominences and Coronal Rain Authors: Liu, W.; Antolin, P.; Sun, X.; Vial, J. C.; Guo, L.; Gibson, S. E.; Berger, T. E.; Okamoto, J.; De Pontieu, B. Bibcode: 2016AGUFMSH43C2587L Altcode: Solar prominences and coronal rain are intimately related phenomena, both involving cool material at chromospheric temperatures within the hot corona and both playing important roles as part of the return flow of the chromosphere-corona mass cycle. At the same time, they exhibit distinct morphologies and dynamics not yet well understood. Quiescent prominences consist of numerous long-lasting, filamentary downflow threads, while coronal rain is more transient and falls comparably faster along well-defined curved paths. We report here a novel, hybrid prominence-coronal rain complex in an arcade-fan geometry observed by SDO/AIA and IRIS, which provides new insights to the underlying physics of such contrasting behaviors. We found that the supra-arcade fan region hosts a prominence sheet consisting of meandering threads with broad line widths. As the prominence material descends to the arcade, it turns into coronal rain sliding down coronal loops with line widths 2-3 times narrower. This contrast suggests that distinct local plasma and magnetic conditions determine the fate of the cool material, a scenario supported by our magnetic field extrapolations from SDO/HMI. Specifically, the supra-arcade fan (similar to those in solar flares) is likely situated in a current sheet, where the magnetic field is weak and the plasma-beta could be close to unity, thus favoring turbulent flows like those prominence threads. In contrast, the underlying arcade has a stronger magnetic field and most likely a low-beta environment, such that the material is guided along magnetic field lines to appear as coronal rain. We will discuss the physical implications of these observations beyond the phenomena of prominences and coronal rain. Title: Where are we with the Pending Issues of Prominence Formation, Lifetime and Eruption? Authors: Vial, J. C. Bibcode: 2016AGUFMSH41E..02V Altcode: As shown by most recent reviews (e.g. Solar Prominences, 2015, ASSL 415), the formation, existence (and eruption) of solar prominences are still a mystery. There are many reasons for that : their complexity in terms of geometry and fine structure, the crucial rôle of the magnetic field (and its difficult measurement), the mixed nature of the plasma (neither neutral nor fully ionized), the rôle of the powerful photospheric, chromospheric and coronal incident radiation in the energy budget, etc ... We propose to have a review of the latest discoveries in the field resulting from the most recent missions (such as IRIS) and ground-based instrumentation along with NLTE and MHD modelling. We will also address some significant results on the connection between Eruptive Prominences and CMEs. Title: Joint SDO and IRIS Observations of a Novel, Hybrid Prominence-Coronal Rain Complex Authors: Liu, Wei; Antolin, Patrick; Sun, Xudong; Gao, Lijia; Vial, Jean-Claude; Gibson, Sarah; Okamoto, Takenori; Berger, Thomas; Uitenbroek, Han; De Pontieu, Bart Bibcode: 2016usc..confE..99L Altcode: Solar prominences and coronal rain are intimately related phenomena, both involving cool material at chromospheric temperatures within the hot corona and both playing important roles as part of the return flow of the chromosphere-corona mass cycle. At the same time, they exhibit distinct morphologies and dynamics not yet well understood. Quiescent prominences consist of numerous long-lasting, filamentary downflow threads, while coronal rain is more transient and falls comparably faster along well-defined curved paths. We report here a novel, hybrid prominence-coronal rain complex in an arcade-fan geometry observed by SDO/AIA and IRIS, which provides new insights to the underlying physics of such contrasting behaviors. We found that the supra-arcade fan region hosts a prominence sheet consisting of meandering threads with broad line widths. As the prominence material descends to the arcade, it turns into coronal rain sliding down coronal loops with line widths 2-3 times narrower. This contrast suggests that distinct local plasma and magnetic conditions determine the fate of the cool material, a scenario supported by our magnetic field extrapolations from SDO/HMI. Specifically, the supra-arcade fan (similar to those in solar flares; e.g., McKenzie 2013) is likely situated in a current sheet, where the magnetic field is weak and the plasma-beta could be close to unity, thus favoring turbulent flows like those prominence threads. In contrast, the underlying arcade has a stronger magnetic field and most likely a low-beta environment, such that the material is guided along magnetic field lines to appear as coronal rain. We will discuss the physical implications of these observations beyond prominence and coronal rain. Title: Automated detection, characterization, and tracking of filaments from SDO data Authors: Buchlin, E.; Mercier, C.; Vial, J. -C. Bibcode: 2016usc..confE.100B Altcode: Thanks to the cadence and continuity of AIA and HMI observations, SDO offers unique data for detecting, characterizing, and tracking solar filaments, until their eruptions, which are often associated with coronal mass ejections. Because of the requirement of short latency when aiming at space weather applications, and because of the important data volume, only an automated detection can be worked out. We present the code "FILaments, Eruptions, and Activations detected from Space" (FILEAS) that we have developed for the automated detection and tracking of filaments. Detections are based on the analysis of AIA 30.4 nm He II images and on the magnetic polarity inversion lines derived from HMI. Following the tracking of filaments as they rotate with the Sun, filament characteristics are computed and a database of filaments parameters is built. We are currently building a database of filament detections by this code, covering the full SDO mission, and that will be made available to the community. Title: A small mission concept to the Sun-Earth Lagrangian L5 point for innovative solar, heliospheric and space weather science Authors: Lavraud, B.; Liu, Y.; Segura, K.; He, J.; Qin, G.; Temmer, M.; Vial, J. -C.; Xiong, M.; Davies, J. A.; Rouillard, A. P.; Pinto, R.; Auchère, F.; Harrison, R. A.; Eyles, C.; Gan, W.; Lamy, P.; Xia, L.; Eastwood, J. P.; Kong, L.; Wang, J.; Wimmer-Schweingruber, R. F.; Zhang, S.; Zong, Q.; Soucek, J.; An, J.; Prech, L.; Zhang, A.; Rochus, P.; Bothmer, V.; Janvier, M.; Maksimovic, M.; Escoubet, C. P.; Kilpua, E. K. J.; Tappin, J.; Vainio, R.; Poedts, S.; Dunlop, M. W.; Savani, N.; Gopalswamy, N.; Bale, S. D.; Li, G.; Howard, T.; DeForest, C.; Webb, D.; Lugaz, N.; Fuselier, S. A.; Dalmasse, K.; Tallineau, J.; Vranken, D.; Fernández, J. G. Bibcode: 2016JASTP.146..171L Altcode: We present a concept for a small mission to the Sun-Earth Lagrangian L5 point for innovative solar, heliospheric and space weather science. The proposed INvestigation of Solar-Terrestrial Activity aNd Transients (INSTANT) mission is designed to identify how solar coronal magnetic fields drive eruptions, mass transport and particle acceleration that impact the Earth and the heliosphere. INSTANT is the first mission designed to (1) obtain measurements of coronal magnetic fields from space and (2) determine coronal mass ejection (CME) kinematics with unparalleled accuracy. Thanks to innovative instrumentation at a vantage point that provides the most suitable perspective view of the Sun-Earth system, INSTANT would uniquely track the whole chain of fundamental processes driving space weather at Earth. We present the science requirements, payload and mission profile that fulfill ambitious science objectives within small mission programmatic boundary conditions. Title: The SPICE Spectral Imager on Solar Orbiter: Linking the Sun to the Heliosphere Authors: Fludra, Andrzej; Haberreiter, Margit; Peter, Hardi; Vial, Jean-Claude; Harrison, Richard; Parenti, Susanna; Innes, Davina; Schmutz, Werner; Buchlin, Eric; Chamberlin, Phillip; Thompson, William; 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; Davila, Joseph; Giunta, Alessandra; Waltham, Nick; Eccleston, Paul; Gottwald, Alexander; Klein, Roman; Hanley, John; Walls, Buddy; Howe, Chris; Schuehle, Udo Bibcode: 2016cosp...41E.607F Altcode: The SPICE (Spectral Imaging of the Coronal Environment) instrument is one of the key remote sensing instruments onboard the upcoming Solar Orbiter Mission. SPICE has been designed to contribute to the science goals of the mission by investigating the source regions of outflows and ejection processes which link the solar surface and corona to the heliosphere. In particular, SPICE will provide quantitative information on the physical state and composition of the solar atmosphere plasma. For example, SPICE will access relative abundances of ions to study the origin and the spatial/temporal variations of the 'First Ionization Potential effect', which are key signatures to trace the solar wind and plasma ejections paths within the heliosphere. Here we will present the instrument and its performance capability to attain the scientific requirements. We will also discuss how different observation modes can be chosen to obtain the best science results during the different orbits of the mission. To maximize the scientific return of the instrument, the SPICE team is working to optimize the instrument operations, and to facilitate the data access and their exploitation. Title: The potential of hydrogen lines for the spectropolarimetry of the solar corona Authors: Vial, Jean-Claude; Chane-Yook, Martine Bibcode: 2016cosp...41E2003V Altcode: Neutral Hydrogen lines have been detected in the hot and ionized solar corona as early as 1970 (Gabriel et al. 1971) and since then with the Spartan and UVCS/SoHO space experiments. Moreover, because of the sensitivity of the Lyman lines to the Hanle effect (Bommier and Sahal-Brechot 1982, Trujillo Bueno et al. 2005), polarization measurements in these lines could lead to the diagnostic of weak magnetic fields in the corona (Derouich et al. 2010), a challenge which has led to various space mission proposals such as LYOT/SMESE or MASC. Our investigation concerns the computation of the emission in 10 selected lines of Hydrogen (Lyman, Balmer, and Paschen) taking into account the proper computation of the NonLTE H ionization and atomic levels populations. We present the results for three different coronal models (streamer, quiet Sun and coronal hole) in terms of profiles and absolute intensities at altitudes varying from 1.05 to 1.9 solar radius. These spectrophotometric results could help for the determination of the space and ground-based polarimetric instrumentation best suited for the measurement of the coronal magnetic field. 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 Bibcode: 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: Automated detection, characterization, and tracking of filaments from SDO data Authors: Buchlin, Eric; Vial, Jean-Claude; Mercier, Claude Bibcode: 2016cosp...41E.258B Altcode: Thanks to the cadence and continuity of AIA and HMI observations, SDO offers unique data for detecting, characterizing, and tracking solar filaments, until their eruptions, which are often associated with coronal mass ejections. Because of the requirement of short latency when aiming at space weather applications, and because of the important data volume, only an automated detection can be worked out. We present the code "FILaments, Eruptions, and Activations detected from Space" (FILEAS) that we have developed for the automated detection and tracking of filaments. Detections are based on the analysis of AIA 30.4 nm He II images and on the magnetic polarity inversion lines derived from HMI. Following the tracking of filaments as they rotate with the Sun, filament characteristics are computed and a database of filaments parameters is built. We present the algorithms and performances of the code, and we compare its results with the filaments detected in Hα and already present in the Heliophysics Events Knowledgebase. We finally discuss the possibility of using such a code to detect eruptions in real time. Title: Non-symmetrical profiles of the C IV 1548A and 1550A lines for small dynamic events and their interpretation in terms of resonant scattering in solar active region Authors: Gontikakis, Costis; Vial, Jean-Claude Bibcode: 2016cosp...41E.702G Altcode: We present observations of small areas in solar active regions recorded with the SUMER/SOHO spectrograph where the C IV 1548A and 1550A lines have spectral profiles of different shapes, although they are recorded simultaneously and at the same location. This asymmetry may be explained by resonant scattering associated with relative velocities of the emitting plasmas. We present detailed artificial spectral profiles that may explain the observations. The profiles have been computed using several physical parameters such as the plasma temperature and electron density and/or the incident radiation on the emitting volumes. We conclude that the study of asymmetries in the C IV 1548A, 1550A lines, and also in different doublets, can be a valuable diagnostic tool for deriving the physical conditions in solar/stellar plasmas, especially where the radiation processes (such as flare-emission) are enhanced at the vicinity of the observed structures. Title: Evidence of scattering effects influenced by plasma flows in C VI 1548 Å, 1550 Å spectral lines emitted from the Sun Authors: Gontikakis, C.; Vial, J. -C. Bibcode: 2016A&A...590A..86G Altcode:
Aims: We search for, and study, individual spectral profiles where the complex shape of the C iv 1548 Å line is different from the shape of the simultaneously recorded C iv 1550 Å line. Such an asymmetry is not expected for line emission resulting from collisional excitation. Therefore we propose an explanation of these observations through the differential effect of velocity fields on resonant scattering.
Methods: We analyse spectra recorded with the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) on the Solar and Heliospheric Observatory (SOHO) over active region, NOAA 8541 as well as a second data set on the quiet Sun. We perform Gaussian fits on the individual profiles with two or three Gaussian functions. Moreover, we parameterize the profile asymmetries by calculating the intensity ratios I1548/I1550, from the derived Gaussian functions. We also calculate artificial spectral profiles emitted from two plasma volumes, which have different line of sight motions and where the plasma emission is influenced by resonant scattering.
Results: We locate three small regions in NOAA 8541 which have spectral asymmetries. There the profiles have two or three spectral components, with different intensity ratios. Artificial profiles show that two plasma volumes, having distinct velocities relative to the observer, may reproduce the observed profiles, under the influence of resonant scattering.
Conclusions: Asymmetric profiles, found in an active region, can be used as a diagnostic for the importance of resonant scattering in transition region plasma. Title: Observed IRIS Profiles of the h and k Doublet of Mg II and Comparison with Profiles from Quiescent Prominence NLTE Models Authors: Vial, Jean-Claude; Pelouze, Gabriel; Heinzel, Petr; Kleint, Lucia; Anzer, Ulrich Bibcode: 2016SoPh..291...67V Altcode: 2015SoPh..tmp..173V With the launch of the Interface Region Imaging Spectrograph (IRIS) mission, it is now possible to obtain high-resolution solar prominence spectra and to begin to distinguish the contributions of the many (apparent or not) threads that structure prominences. We aim at comparing unique observations obtained in the Mg II h and k lines of a polar crown prominence with the radiative outputs from one-dimensional models built with non-local-thermodynamic equilibrium codes (Heinzel et al.Astron. Astrophys.564, A132, 2014). We characterize the profiles obtained through thorough calibration procedures, with attention paid to the absolute values, full-width at half-maximum, and the ratio of k to h intensities. We also show that at the top of some structures, line-of-sight velocities of about 9 kms−1 can be detected. We find a range of static, low-pressure, low-thickness, low-temperature models that could fit k or h observed values, but that cannot satisfy the low observed k/h ratio. We investigate whether these low values might be explained by the inclusion of horizontal flows in small-scale threads. These flows are also necessary in another class of models, where the pressure is kept low but thickness and temperature are increased up to the observed thickness and up to 15 000 K. Title: Hydrogen Ly-α and Ly-β full Sun line profiles observed with SUMER/SOHO (1996-2009) Authors: Lemaire, P.; Vial, J. -C.; Curdt, W.; Schühle, U.; Wilhelm, K. Bibcode: 2015A&A...581A..26L Altcode: Context. Accurate hydrogen spectra emitted by the entire solar disc in the Ly-α and Ly-βlines are valuable for deriving the distribution and the behaviour of atomic hydrogen in the heliosphere, for understanding the UV emissions of solar type stars better, and finally for estimating the solar energy input that mainly initiates the chemical processes occurring in the planetary and cometary outer atmospheres.
Aims: In this paper we want to accurately determine the irradiance solar spectral profiles of Ly-α and Ly-β and their evolution through the solar activity cycle 23.
Methods: The SUMER/SOHO spectrometer is a slit spectrometer that is only able to analyse a small part of the solar image. Consequently, we used the scattered light properties of the telescope to obtain average spectra over the solar disc. Then the profile is calibrated using the SOLSTICE/UARS and TIMED/SEE irradiance spectra.
Results: We obtained a set of irradiance Ly-α and Ly-β solar spectra with a 0.002 nm resolution through the solar activity cycle 23. In each line a relation between the integrated profile and the line centre intensity was obtained.Knowing the line irradiance, it is possible to deduce the central line profile intensity, a critical input into the interplanetary and planetary oxygen and hydrogen fluorescent processes.
Conclusions: The observation of H i Ly-α and Ly-β line profiles by SUMER/SOHO during the cycle 23 allows analysis of the evolution of their characteristics and accurate determination of UV radiation input into the solar system.

Profiles are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/581/A26 Title: VizieR Online Data Catalog: Sun hydrogen Lyman irradiance lines profiles (Lemaire+, 2015) Authors: Lemaire, P.; Vial, J. -C.; Curdt, W.; Schuhle, U.; Wilhelm, K. Bibcode: 2015yCat..35810026L Altcode: Set of irradiance Ly-α and Ly-β solar spectra with a 0.002nm resolution through the solar activity cycle 23. The wavelength distance from line center is given every 0.001nm.

(2 data files). Title: First High-resolution Spectroscopic Observations of an Erupting Prominence Within a Coronal Mass Ejection by the Interface Region Imaging Spectrograph (IRIS) Authors: Liu, Wei; De Pontieu, Bart; Vial, Jean-Claude; Title, Alan M.; Carlsson, Mats; Uitenbroek, Han; Okamoto, Takenori J.; Berger, Thomas E.; Antolin, Patrick Bibcode: 2015ApJ...803...85L Altcode: 2015arXiv150204738L Spectroscopic observations of prominence eruptions associated with coronal mass ejections (CMEs), although relatively rare, can provide valuable plasma and three-dimensional geometry diagnostics. We report the first observations by the Interface Region Imaging Spectrograph mission of a spectacular fast CME/prominence eruption associated with an equivalent X1.6 flare on 2014 May 9. The maximum plane-of-sky and Doppler velocities of the eruption are 1200 and 460 km s-1, respectively. There are two eruption components separated by ∼200 km s-1 in Doppler velocity: a primary, bright component and a secondary, faint component, suggesting a hollow, rather than solid, cone-shaped distribution of material. The eruption involves a left-handed helical structure undergoing counterclockwise (viewed top-down) unwinding motion. There is a temporal evolution from upward eruption to downward fallback with less-than-free-fall speeds and decreasing nonthermal line widths. We find a wide range of Mg ii k/h line intensity ratios (less than ∼2 expected for optically-thin thermal emission): the lowest ever reported median value of 1.17 found in the fallback material, a comparably high value of 1.63 in nearby coronal rain, and intermediate values of 1.53 and 1.41 in the two eruption components. The fallback material exhibits a strong (\gt 5σ ) linear correlation between the k/h ratio and the Doppler velocity as well as the line intensity. We demonstrate that Doppler dimming of scattered chromospheric emission by the erupted material can potentially explain such characteristics. Title: The Balmer Lines of He II in the Blue Wing of the Hydrogen Lyman α Line Observed in a Quiescent Prominence Authors: Vial, J. -C.; Eurin, G.; Curdt, W. Bibcode: 2015SoPh..290..381V Altcode: We revisit the prominence observations in the Lyman α line of Curdt et al. (Astron. Astrophys.511, L4, 2010) and focus on the bump in the blue wing of the line, which we identify with He II Balmer lines. We determine the transition candidates, derive an upper limit for the width of the profile and an associated non-thermal velocity close to 0 km s−1, with the assumption that the kinetic temperature is equal to the formation temperature. We compare the total intensity with the corresponding H Lyman α intensity and find a ratio much lower than that measured by Ebadi, Vial, and Ajabshirizadeh (Solar Phys.257, 91, 2009) in other Lyman lines. We confirm this result with observations performed by Schwartz et al. (private communication, 2014), we discuss a possible interpretation, and suggest that this issue needs to be addressed closely in future observations. Title: Solar Prominences Authors: Vial, Jean-Claude; Engvold, Oddbjørn Bibcode: 2015ASSL..415.....V Altcode: No abstract at ADS Title: Historical Background and Introduction Authors: Vial, Jean-Claude Bibcode: 2015ASSL..415....1V Altcode: Forty and twenty years after the two books published by Einar Tandberg-Hanssen (Solar prominences (Geophysics and astrophysics monographs), Vol. 12. Dordrecht: D. Reidel Publishing Co., 1974; The nature of solar prominences, astrophysics and space science library, Vol. 199. Dordrecht: Kluwer Academic Publishers, 1995) on solar prominences, it is time to update our knowledge and understanding of these fascinating solar structures. After a brief history which overviews first eclipse observations (drawings and then photography), spectrographic, coronagraphic and later on polarimetric measurements, the chapter presents samples of the most spectacular results of the last two decades, obtained whether from space or on the ground. It discusses the contents of the book in order to encourage the reader to dip into the following 17 chapters which provide comprehensive and detailed observations, information about the methods used, and interpretation of the results on the basis of the latest theoretical and modelling works. Title: Instant: An Innovative L5 Small Mission Concept for Coordinated Science with Solar Orbiter and Solar Probe Plus Authors: Lavraud, B.; Liu, Y. D.; Harrison, R. A.; Liu, W.; Auchere, F.; Gan, W.; Lamy, P. L.; Xia, L.; Eastwood, J. P.; Wimmer-Schweingruber, R. F.; Zong, Q.; Rochus, P.; Maksimovic, M.; Temmer, M.; Escoubet, C. P.; Kilpua, E.; Rouillard, A. P.; Davies, J. A.; Vial, J. C.; Gopalswamy, N.; Bale, S. D.; Li, G.; Howard, T. A.; DeForest, C. E. Bibcode: 2014AGUFMSH21B4109L Altcode: We will present both the science objectives and related instrumentation of a small solar and heliospheric mission concept, INSTANT: INvestigation of Solar-Terrestrial Activity aNd Transients. It will be submitted as an opportunity to the upcoming ESA-China S-class mission call later this year. This concept was conceived to allow innovative measurements and unprecedented, early determination of key properties of Earthbound CMEs from the L5 vantage point. Innovative measurements will include magnetic field determination in the corona thanks to Hanle measurement in Lyman-α and polarized heliospheric imaging for accurate determination of CME trajectories. With complementary in situ measurements, it will uniquely permit solar storm science, solar storm surveillance, and synergy with Solar Orbiter and Solar Probe Plus (the ESA-China S2 mission launch is planned in 2021). Title: First High-resolution Spectroscopic Observations by IRIS of a Fast, Helical Prominence Eruption Associated with a Coronal Mass Ejection Authors: Liu, W.; De Pontieu, B.; Okamoto, T. J.; Vial, J. C.; Title, A. M.; Antolin, P.; Berger, T. E.; Uitenbroek, H. Bibcode: 2014AGUFMSH11D..04L Altcode: High-resolution spectroscopic observations of prominence eruptions and associated coronal mass ejections (CMEs) are rare but can provide valuable plasma and energy diagnostics. New opportunities have recently become available with the advent of the Interface Region Imaging Spectrograph (IRIS) mission equipped with high resolution of 0.33-0.4 arcsec in space and 1 km/s in velocity, together with the Hinode Solar Optical Telescope of 0.2 arcsec spatial resolution. We report the first result of joint IRIS-Hinode observations of a spectacular prominence eruption occurring on 2014-May-09. IRIS detected a maximum redshift of 450 km/s, which, combined with the plane-of-sky speed of 800 km/s, gives a large velocity vector of 920 km/s at 30 degrees from the sky plane. This direction agrees with the source location at 30 degrees behind the limb observed by STEREO-A and indicates a nearly vertical ejection. We found two branches of redshifts separated by 200 km/s appearing in all strong lines at chromospheric to transition-region temperatures, including Mg II k/h, C II, and Si IV, suggesting a hollow, rather than solid, cone in the velocity space of the ejected material. Opposite blue- and redshifts on the two sides of the prominence exhibit corkscrew variations both in space and time, suggestive of unwinding rotations of a left-handed helical flux rope. Some erupted material returns as nearly streamline flows, exhibiting distinctly narrow line widths (~10 km/s), about 50% of those of the nearby coronal rain at the apexes of coronal loops, where the rain material is initially formed out of cooling condensation. We estimate the mass and kinetic energy of the ejected and returning material and compare them with those of the associated CME. We will discuss the implications of these observations for CME initiation mechanisms. Title: On the formation of Mg ii h and k lines in solar prominences Authors: Heinzel, P.; Vial, J. -C.; Anzer, U. Bibcode: 2014A&A...564A.132H Altcode:
Aims: With the recent launch of the IRIS mission, it has become urgent to develop the spectral diagnostics using the Mg ii resonance h and k lines. In this paper, we aim to demonstrate the behavior of these lines under various prominence conditions. Our results serve as a basis for analysis of new IRIS data and for more sophisticated prominence modeling.
Methods: For this exploratory work, we use a canonical 1D prominence-slab model, which is isobaric and may have three different temperature structures: isothermal, PCTR-like (prominence-corona transition region), and consistent with the radiative equilibrium. The slabs are illuminated by a realistic incident solar radiation obtained from the UV observations. A five-level plus continuum Mg ii model atom is used to solve the full NLTE problem of the radiative transfer. We use the numerical code based on the ALI techniques and apply the partial frequency redistribution for both Mg ii resonance lines. We also use the velocity-dependent boundary conditions to study the effect of Doppler dimming in the case of moving prominences. Finally, the relaxation technique is used to compute a grid of models in radiative equilibrium.
Results: We computed the Mg ii h and k line profiles that are emergent from prominence-slab models and show their dependence on kinetic temperature, gas pressure, geometrical extension, and microturbulent velocity. By increasing the line opacity, significant departures from the complete frequency redistribution take place in the line wings. Models with a PCTR temperature structure show that Mg ii becomes ionized to Mg iii in the temperature range between roughly 15 000 and 30 000 K. Doppler dimming is significant for Mg ii resonance lines. At the velocity 300 km s-1, the line intensity decreases to about 20% of the value for static prominences. Finally, we demonstrate the role of Mg ii h and k radiation losses on the prominence energy balance. Their dominant role is at lower pressures, while the losses due to hydrogen and Ca ii dominate at higher pressures. Title: A comparison between observed IRIS profiles of the h & k doublet of Mg II and profiles from quiescent prominence NLTE models Authors: Vial, Jean-Claude; Anzer, Ulrich; Heinzel, Petr; Kleint, Lucia Bibcode: 2014cosp...40E3515V Altcode: With the advent of IRIS, it is now possible to investigate the cool core of prominences through the detailed profiles of the Mg II resonance lines with an unprecedented spatial resolution of 0.33 arcsecond. The slit-jaw camera also allows to record the temporal evolution of the prominence fine structure. We present IRIS observations of quiescent prominence profiles that we analyse in terms of reversal (if any), width, k/h line ratio, prominence/ quiet Sun line ratio. Comparing these parameters with the results of NLTE modelling (see Heinzel et al. 2014), we can derive thermodynamic parameters of the cool prominence plasma, along with the (line-of-sight) velocities and mass flows. Title: INSTANT: INvestigation of Solar-Terrestrial Associated Natural Threats Authors: Lavraud, Benoit; Vial, Jean-Claude; Harrison, Richard; Davies, Jackie; Escoubet, C. Philippe; Zong, Qiugang; Auchere, Frederic; Liu, Ying; Bale, Stuart; Gopalswamy, Nat; Li, Gang; Maksimovic, Milan; Liu, William; Rouillard, Alexis Bibcode: 2014cosp...40E1758L Altcode: The INSTANT mission will tackle both compelling solar and heliospheric science objectives and novel space weather capabilities. This is allowed by combining innovative and state-of-the-art instrumentation at an appropriate off-Sun-Earth line location on an orbit lagging the Earth around the Sun, near the L5 Lagrangian point. It is an affordable mission that tackles major objectives of the European and Chinese communities in terms of space physics and space weather. The science objectives are: 1. What is the magnetic field magnitude and topology in the corona? 2. How does the magnetic field reconfigure itself during CME eruptions? 3. What are the sources and links between the slow and fast winds? 4. How do CMEs accelerate and interact in the interplanetary medium? The mission will further allow the following crucial space weather capabilities: 5. Three-days advance knowledge of CIR properties that reach Earth. 6. Twelve hours to 2 days advance warning of Earth-directed CMEs. 7. Thanks to Lyman-α observations, first-ever capability of determining the magnetic field magnitude and orientation of Earth-directed CMEs. The mission will be proposed in the context of the upcoming ESA-China S-class call for mission. Title: MASC: Magnetic Activity of the Solar Corona Authors: Auchere, Frederic; Fineschi, Silvano; Gan, Weiqun; Peter, Hardi; Vial, Jean-Claude; Zhukov, Andrei; Parenti, Susanna; Li, Hui; Romoli, Marco Bibcode: 2014cosp...40E.149A Altcode: We present MASC, an innovative payload designed to explore the magnetic activity of the solar corona. It is composed of three complementary instruments: a Hard-X-ray spectrometer, a UV / EUV imager, and a Visible Light / UV polarimetric coronagraph able to measure the coronal magnetic field. The solar corona is structured in magnetically closed and open structures from which slow and fast solar winds are respectively released. In spite of much progress brought by two decades of almost uninterrupted observations from several space missions, the sources and acceleration mechanisms of both types are still not understood. This continuous expansion of the solar atmosphere is disturbed by sporadic but frequent and violent events. Coronal mass ejections (CMEs) are large-scale massive eruptions of magnetic structures out of the corona, while solar flares trace the sudden heating of coronal plasma and the acceleration of electrons and ions to high, sometimes relativistic, energies. Both phenomena are most probably driven by instabilities of the magnetic field in the corona. The relations between flares and CMEs are still not understood in terms of initiation and energy partition between large-scale motions, small-scale heating and particle acceleration. The initiation is probably related to magnetic reconnection which itself results magnetic topological changes due to e.g. flux emergence, footpoints motions, etc. Acceleration and heating are also strongly coupled since the atmospheric heating is thought to result from the impact of accelerated particles. The measurement of both physical processes and their outputs is consequently of major importance. However, despite its fundamental importance as a driver for the physics of the Sun and of the heliosphere, the magnetic field of our star’s outer atmosphere remains poorly understood. This is due in large part to the fact that the magnetic field is a very difficult quantity to measure. Our knowledge of its strength and orientation is primarily based on extrapolations from photospheric observations, not from direct measurements. These extrapolations require strong assumptions on critical but unobserved quantities and thus fail to accurately reproduce the complex topologies inferred from remote-sensing observations of coronal structures in white light, EUV, and X-rays. Direct measurements of the coronal magnetic field are also clearly identified by the international heliophysics community as a key element susceptible to lead to major breakthroughs in the understanding of our star. MASC is thus designed to answer the following top-level scientific questions: 1. What is the global magnetic field configuration in the corona? 2. What is the role of the magnetic field in the triggering of flares and CMEs? 3. What is the role of the magnetic field in the acceleration mechanisms of the solar winds? 4. What is the energy spectrum and in particular what are the highest energies to which charged particles can be accelerated in the solar corona? MASC will address these fundamental questions with a suite of instruments composed of an X-ray spectrometer, a UV / EUV imager, and a coronagraph working in the visible and at Lyman alpha. The spectrometer will provide information on the energetics of solar flares, in particular at very high energies of accelerated particles. The UV / EUV imager will provide constraints on the temperature of the flaring and non-flaring corona. The coronagraph will provide the number density of free electrons in the corona, maps of the outflow velocity of neutral hydrogen, and measurements of the coronal magnetic field, via the Hanle effect. These measurements will be performed at all steps of the flare-CME processes, thus providing a detailed picture of the solar coronal dynamics in the quiet and eruptive periods. Title: Automated detection, characterization, and tracking of filaments from SDO data Authors: Buchlin, Eric; Vial, Jean-Claude; Mercier, Claude; Goujon, Jean-Baptiste Bibcode: 2014cosp...40E.425B Altcode: Thanks to the cadence and continuity of AIA and HMI observations, SDO offers unique data for detecting, characterizing, and tracking solar filaments, until their eruptions, which are often associated with coronal mass ejections. Because of the requirement of short latency when aiming at space weather applications, and because of the important data volume, only an automated detection can be worked out. We present the code "FILaments, Eruptions, and Activations detected from Space" (FILEAS) that we have developed for the automated detection and tracking of filaments. Detections are based on the analysis of AIA 30.4 nm He II images and on the magnetic polarity inversion lines derived from HMI. Following the tracking of filaments as they rotate with the Sun, filament characteristics are computed and a database of filaments parameters is built. We present the algorithms and performances of the code, and we compare its results with the filaments detected in Halpha and already present in the Heliophysics Events Knowledgebase. We finally discuss the possibility of using such a code to detect eruptions in real time. Title: On the nature of the prominence - corona transition region Authors: Parenti, Susanna; Vial, Jean-Claude Bibcode: 2014IAUS..300...69P Altcode: Due to the complexity of their environment, prominences properties are still a matter of controversy. Prominences cool and dense plasma is suspended in the hot corona by a magnetic structure poorly known. Their thermal insulation from the corona results in a thin geometrical interface called prominence-corona-transition-region (PCTR). Here we will review the main properties of such a region as derived primarily from observations. We will introduce the thermal structure properties, describe the fine structure together with the Doppler-shift and width properties of lines of the emitting plasma. We will introduce the proposed interpretations of such observations and the limits of our knowledge imposed by the present instrumentation. We will conclude with a perspective for the future observations of the PCTR. Title: The EUV photosphere- corona interface from eclipses to study the origin of low- FIP elements and the root of the basis of the chromosphere Authors: Bazin, Cyrille; Veselovsky, Igor; Vial, Jean-Claude; Tavabi, Ehsan; Serge, Koutchmy Bibcode: 2014cosp...40E.236B Altcode: We use the full occultation of the Sun by the Moon to study the upper solar atmosphere with flash spectra free of any parasitic light from the disc. A radial resolution of 40 km is obtained from unique images in many emission lines seen as crescents of the low atmosphere. The natural motion of the lunar limb probes the photosphere - corona interface where the solar magnetic field emerges. High cadence CCD slitless flash spectra obtained before and after the eclipse totality (in 2008, 2009, 2010, 2012, and 2013) show that the over-abundance of the low First Ionisation Potential elements (low FIP) like FeII, TiII, BaII, etc. comes from the interface layers close to the temperature minimum. For the 1st time, the solar edge is defined by considering the “true” continuum analysed outside of faint emission lines at heights ranging from 0.2 to 0.6 Mm. We also measure the helium shells of He I 4713Å and of He II 4686Å (Paschen alpha, optically thin high FIP lines), starting at the height of 0.8 Mm. Enhancements of the high FIP lines (H beta, He I and He II) are found at altitudes lower than 0.8 Mm above the limb from new 2013 spectra. The extensions of the helium shells are compared in equatorial and Polar Regions. The widths of the lines are evaluated for the 1st time. The light curves I = f(h) corresponding to low FIP ions are measured for different positions of the low solar atmosphere. The scale heights correspond to radial density gradients allowing temperature evaluations in case of the hydrostatic assumptions. We also demonstrate some density gradient analogies between the photosphere- corona and the prominence-corona interface using the Ti II lines as a marker. The effect of the magnetic field emergence for supplying mass to the corona through low FIP elements is discussed. A simultaneously obtained 193 SDO/AIA processed image is used to discuss what the coronal extensions are. Title: On the development of a Fourier Transform Spectrometer for Solar Physics Authors: Ruiz de Galarreta, Claudia; Vial, Jean-Claude; Appourchaux, Thierry; Philippon, Anne Bibcode: 2014cosp...40E2793R Altcode: The origin and the evolution of the different structures that inhabit beyond the Sun’s photosphere, as well as the processes involved in the dynamics and the heating of the corona remain quite unknown. The inextricable complexity of the physical phenomena that govern the solar outer atmosphere is accompanied by the lack of suitable data adapted to the scientific need. Indeed, the interpretation and the models of the mechanisms that connect the exchanges between the chromosphere and the corona depend on critical observational parameters. It is for example essential to measure broad bands of vertical temperature and density ranges that fit the multiple spatial and temporal scales that are characteristic of the different events that take place in the Sun. The understanding of the dynamics of the plasma must be also based on the Doppler analysis of the observed scene. That implies the ability to combine time resolved spectroscopic and imaging technologies. Moreover, space is the place to observe the far UV corona and that implies a real technical challenge. Despite excellent advances in technology and instrumentation, the study of the Sun in the far UV is a fairly recent science. To date, no solar space mission could provide a combined and simultaneous diagnostic of both observables in the spectral range of interest. It is because of these expectations that the study of a new device called IFTSUV (the acronym of Imaging Fourier Transform Spectrometer working in the far UV) is presented in this paper. We start from the definition of the scientific requirements that lead to the technical choice, the first objective of this study is to develop a preliminary instrumental model of the IFTSUV. The overall technical and design specifications are based in theoretical calculations that have been expressed in terms of spectral accuracy, image quality and signal to noise ratio. Throughout the identification of difficult points, the realization of a servo-metrology system to control the sampling mirror appears naturally as an intrinsic need of proof of concept. Indeed, the wavenumbers from the raw spectra are set by the interferogram. That implies that acquisition must be rigorously constant and that the sampling steps must be known with high accuracy. Therefore, the mockup of a metrological solution that has been developped at IAS will is also presented. The results on the damonstrator that validate and converge to the optimization and prototyping of a system that could be integrated in a space based application will be discussed. Finally we propose a discussion on the possible future space mission opportunities in which this innovative project could be framed. Title: The LYOT+ UV/EUV instrumentation for measuring the magnetic field in the corona Authors: Auchère, Frederic; Vial, Jean Claude Bibcode: 2013EGUGA..1513788A Altcode: The solar corona is the seat of a variability which involves basic processes of plasma-magnetic field interaction in the universe, while also being a source of disturbances for spacecraft, technology, and possibly for human beings. Of special interest are coronal mass ejections (CMEs) with their associated Eruptive Prominences (EPs). Since they are basically driven by instabilities of the magnetic field in the corona, the measurement of the magnetic field before, after (and during) the event is critical in the corona. Also of interest for these studies and the source of the solar wind, the radial velocity of the plasma is a critical parameter to be determined. We present a new proposal to CNES called LYOT+ which meets the above-mentioned objectives: measurement of the coronal magnetic field up to 2 solar radii, of the electron density and the radial velocity. These measurements are complemented by EUV images of the underlying corona providing plasma diagnostic and magnetic field morphology. We describe the proposed combination of EUV imager and VUV and visible coronagraph. A main feature of the proposed instrumentation is the extended overlap of the fields-of-view of both instruments. In our presentation, we focus on the polarimetric concept which leads to the determination of the magnetic field through the Hanle effect. We also mention the extensive studies already performed in designing the instrumentation and testing parts of it. In summary, science, instrumentation and constraints on missions on which LYOT+ could be implemented, are presented. Title: Nature and Variability of Plasmas Ejected by the Sun Authors: Vial, J. -C. Bibcode: 2013LNP...857...15V Altcode: The Sun not only emits radiation in the whole electromagnetic spectrum but also sends in the interplanetary medium plasmas of different natures (energy, continuous, or episodic flows, etc.) which contribute to its (small) mass loss. The escaping material when properly oriented may impact on the Earth magnetic environment with cascading effects on the Earth atmosphere. The continuous flow known as the solar wind is actually made of two categories, slow and fast winds. We discuss their properties, sources, and the mechanisms at work through the two types of models (fluid and particles). We describe the sporadic mass losses for the three main typical events: flares, prominence ejection, and coronal mass ejection. We discuss a possible unifying scenario which takes into account these three manifestations of magnetic disruption. We also extend the investigation to the whole heliosphere. Our conclusion proposes a few goals concerning the diagnostic and the understanding of the plasmas ejected by the Sun, along with the space missions which could provide some answers. Title: LEMUR: Large European module for solar Ultraviolet Research. European contribution to JAXA's Solar-C mission Authors: Teriaca, Luca; Andretta, Vincenzo; Auchère, Frédéric; Brown, Charles M.; Buchlin, Eric; Cauzzi, Gianna; Culhane, J. Len; Curdt, Werner; Davila, Joseph M.; Del Zanna, Giulio; Doschek, George A.; Fineschi, Silvano; Fludra, Andrzej; Gallagher, Peter T.; Green, Lucie; Harra, Louise K.; Imada, Shinsuke; Innes, Davina; Kliem, Bernhard; Korendyke, Clarence; Mariska, John T.; Martínez-Pillet, Valentin; Parenti, Susanna; Patsourakos, Spiros; Peter, Hardi; Poletto, Luca; Rutten, Robert J.; Schühle, Udo; Siemer, Martin; Shimizu, Toshifumi; Socas-Navarro, Hector; Solanki, Sami K.; Spadaro, Daniele; Trujillo-Bueno, Javier; Tsuneta, Saku; Dominguez, Santiago Vargas; Vial, Jean-Claude; Walsh, Robert; Warren, Harry P.; Wiegelmann, Thomas; Winter, Berend; Young, Peter Bibcode: 2012ExA....34..273T Altcode: 2011ExA...tmp..135T; 2011arXiv1109.4301T The solar outer atmosphere is an extremely dynamic environment characterized by the continuous interplay between the plasma and the magnetic field that generates and permeates it. Such interactions play a fundamental role in hugely diverse astrophysical systems, but occur at scales that cannot be studied outside the solar system. Understanding this complex system requires concerted, simultaneous solar observations from the visible to the vacuum ultraviolet (VUV) and soft X-rays, at high spatial resolution (between 0.1'' and 0.3''), at high temporal resolution (on the order of 10 s, i.e., the time scale of chromospheric dynamics), with a wide temperature coverage (0.01 MK to 20 MK, from the chromosphere to the flaring corona), and the capability of measuring magnetic fields through spectropolarimetry at visible and near-infrared wavelengths. Simultaneous spectroscopic measurements sampling the entire temperature range are particularly important. These requirements are fulfilled by the Japanese Solar-C mission (Plan B), composed of a spacecraft in a geosynchronous orbit with a payload providing a significant improvement of imaging and spectropolarimetric capabilities in the UV, visible, and near-infrared with respect to what is available today and foreseen in the near future. The Large European Module for solar Ultraviolet Research (LEMUR), described in this paper, is a large VUV telescope feeding a scientific payload of high-resolution imaging spectrographs and cameras. LEMUR consists of two major components: a VUV solar telescope with a 30 cm diameter mirror and a focal length of 3.6 m, and a focal-plane package composed of VUV spectrometers covering six carefully chosen wavelength ranges between 170 Å and 1270 Å. The LEMUR slit covers 280'' on the Sun with 0.14'' per pixel sampling. In addition, LEMUR is capable of measuring mass flows velocities (line shifts) down to 2 km s - 1 or better. LEMUR has been proposed to ESA as the European contribution to the Solar C mission. Title: Metrology for a solar imaging Fourier transform spectrometer working in the far UV: from the instrumental concept to the first experimental results Authors: Ruiz de Galarreta Fanjul, C.; Bouzit, M.; Appourchaux, T.; Dassas, K.; Viale, T.; Philippon, A.; Vial, J. -C.; Maillard, J. -P. Bibcode: 2012SPIE.8450E..0DR Altcode: The spectroscopy of the far UV emission lines of the solar spectrum combined with an imaging capability is essential to understand the physics of the outer solar atmosphere. An imaging Fourier transform spectrometer (IFTSUV) is an attractive instrumental solution to perform such far-UV solar observations. Working in the far UV involves high precision metrology to maintain the optical path difference (OPD) during the entire scanning process of the interferogram. It also involves a compact all-reflection design for UV applications. We present the specification of a servo-system that enables dynamic tip/tilt alignment compensation and OPD sampling measurement of the IFTSUV scanning mirror. We also discuss the first experimental results of a breadboard as well as the preliminary design of a space-based device. Title: Flows in a Small Active Region as Seen by Hinode and SoHO Authors: Boutry, C.; Buchlin, É.; Vial, J. Bibcode: 2012ASPC..454..233B Altcode: We report on a multi-instrument study performed on Active Region 10943 located at Sun center on 20 Feb. 2007. We use XRT images, magnetic field maps from SoHO/MDI and we focus on EIS spectra from which we build maps of the Doppler shift and intensity of Fe XII 195.12 Å. We paid a special attention to the absolute wavelength calibration taking into account the orbital temperature effect. We observe coronal loops between opposite polarities of the region and straight downflows seen in faint regions. Title: Flows at the Edge of an Active Region: Observation and Interpretation Authors: Boutry, C.; Buchlin, E.; Vial, J. -C.; Régnier, S. Bibcode: 2012ApJ...752...13B Altcode: 2012arXiv1204.1377B Upflows observed at the edges of active regions have been proposed as the source of the slow solar wind. In the particular case of Active Region (AR) 10942, where such an upflow has been already observed, we want to evaluate the part of this upflow that actually remains confined in the magnetic loops that connect AR 10942 to AR 10943. Both active regions were visible simultaneously on the solar disk and were observed by STEREO/SECCHI EUVI. Using Hinode/EIS spectra, we determine the Doppler shifts and densities in AR 10943 and AR 10942 in order to evaluate the mass flows. We also perform magnetic field extrapolations to assess the connectivity between AR 10942 and AR 10943. AR 10943 displays a persistent downflow in Fe XII. Magnetic extrapolations including both ARs show that this downflow can be connected to the upflow in AR 10942. We estimate that the mass flow received by AR 10943 areas connected to AR 10942 represents about 18% of the mass flow from AR 10942. We conclude that the upflows observed on the edge of active regions represent either large-scale loops with mass flowing along them (accounting for about one-fifth of the total mass flow in this example) or open magnetic field structures where the slow solar wind originates. Title: Automated detection of filaments from He II images Authors: Buchlin, E.; Mercier, C.; Vial, J. -C. Bibcode: 2012EAS....55..175B Altcode: For space weather applications, it is important to understand filaments evolution and especially their eruptions associated with coronal mass ejections. In view of the cadence and continuity of SDO observations, AIA and HMI offer a unique tool for such a program. Because of the data volume and the requirement of short latency, only an automated detection can be worked out. We present a new method for the automated detection and tracking of filaments, based on the analysis of AIA 30.4 nm He ii images, with the capability to use also the magnetic field measured by HMI. Title: The solar hydrogen Lyman α to Lyman β line ratio Authors: Lemaire, P.; Vial, J. -C.; Curdt, W.; Schühle, U.; Woods, T. N. Bibcode: 2012A&A...542L..25L Altcode:
Aims: We investigate the variation in the solar hydrogen Lyman α (Lyα) to Lyman β (Lyβ) line ratio as a function of the solar activity by taking into account new results obtained by SoHO/SUMER and TIMED/SEE.
Methods: We reanalyze data of quiet and active regions previously collected with the LPSP multichannel instrument on OSO8. We then re-examine data obtained on the solar disk with SUMER and compare them with previous data. In a second step, we use the full Sun H i Lyβ profiles to determine the Lyβ contribution to the SEE profiles obtained with a 0.4 nm full width at half-maximum. The variation in the Lyα to Lyβ line ratio is then measured for part of the solar cycle 23 (2002-2008).
Results: We determine the radiance line ratio of the solar H i Lyα to Lyβ line for a quiet Sun area and the relation between the ratio of the Lyα to Lyβ irradiance and the Lyα solar irradiance. Title: High spatial resolution VAULT H-Lyα observations and multiwavelength analysis of an active region filament Authors: Vial, J. -C.; Olivier, K.; Philippon, A. A.; Vourlidas, A.; Yurchyshyn, V. Bibcode: 2012A&A...541A.108V Altcode: Context. The search for the fine structure of prominences has received considerable new attention thanks to the Swedish Solar Telescope (SST) Hα pictures that provide an unsurpassed spatial resolution. Recently, it has been shown that the filaments' coronal environment, at least for quiescent filaments, is perturbed by either cool absorbing material (in the EUV) or an "emissivity blocking" (actually a lack of transition region and coronal material).
Aims: The aim is to assess the fine structure in an active region filament and to determine the nature of the EUV absorption or lack of emission phenomena, using the very optically thick line H-Lyα, formed at a temperature higher than Hα.
Methods: We performed a multiwavelength study where high-resolution imaging in the H-Lyα line (VAULT) was analysed and compared with observations of an active region filament in Hα (BBSO) and EUV lines (EIT and TRACE).
Results: As for the SST data, small-scale structures were detected at a typical scale of about one to two arcseconds with, for some cuts, an indication of fine scales down to 0.4 arcsec in the optically thick H-Lyα line. The filament intensity relative to the intensity of the (active) region it is embedded in is about 0.2 in H-Lyα. This ratio (Lymanα ratio intensity or "LRI") is the lowest value compared to other lines, e.g. Hα. The filament environment was also investigated and evidence of an UV extension was found. The comparison of spatial cuts in different lines across the filament shows evidence of strong absorption, and consequently of cool plasma on one side of the filament, but not on the other (that side is obscured by the filament itself).
Conclusions: The absence of very fine structure in H-Lyα compared to Hα is explained by the formation temperature of the H-Lyα line (~20 000 K), where the transition regions of the thin threads begin to merge. From the detection of H-Lyα absorption on the observable side of the filament side, we derive the presence of absorbing (cool) material and possibly also of emissivity blocking (or coronal void). This poses the question whether these absorption effects are typical of active region filaments.

Appendix A is available in electronic form at http://www.aanda.org Title: Flows in the Vicinity of Two Active Regions as Seen by Hinode, STEREO, and SoHO Authors: Boutry, C.; Buchlin, E'.; Vial, J.; Régnier, S. Bibcode: 2012ASPC..455...83B Altcode: We observed active region 10943 located at Sun center on February 20, 2007 and we characterized its interactions with active region 10942 by using a multi-instrument comparison between Hinode/XRT and STEREO/SECCHI images, magnetic field maps from SoHO/MDI, and Hinode/EIS spectra from which we built maps of the Doppler shift and the intensity of the Fe XII 195.12 Å line. The results are consistent with some material exchange between the two regions separated by 400″. Title: Kinematics and helicity evolution of a loop-like eruptive prominence Authors: Koleva, K.; Madjarska, M. S.; Duchlev, P.; Schrijver, C. J.; Vial, J. -C.; Buchlin, E.; Dechev, M. Bibcode: 2012A&A...540A.127K Altcode: 2012arXiv1202.4541K
Aims: We aim at investigating the morphology as well as kinematic and helicity evolution of a loop-like prominence during its eruption.
Methods: We used multi-instrument observations from AIA/SDO, EUVI/STEREO and LASCO/SoHO. The kinematic, morphological, geometrical, and helicity evolution of a loop-like eruptive prominence were studied in the context of the magnetic flux rope model of solar prominences.
Results: The prominence eruption evolved as a height-expanding twisted loop with both legs anchored in the chromosphere of a plage area. The eruption process consisted of a prominence activation, acceleration, and a phase of constant velocity. The prominence body was composed of counter-clockwise twisted threads around the main prominence axis. The twist during the eruption was estimated at 6π (3 turns). The prominence reached a maximum height of 526 Mm before contracting to its primary location and was partially reformed in the same place two days after the eruption. This ejection, however, triggered a coronal mass ejection (CME) observed in LASCO C2. The prominence was located in the northern periphery of the CME magnetic field configuration and, therefore, the background magnetic field was asymmetric with respect to the filament position. The physical conditions of the falling plasma blobs were analysed with respect to the prominence kinematics.
Conclusions: The same sign of the prominence body twist and writhe, as well as the amount of twisting above the critical value of 2π after the activation phase indicate that possibly conditions for kink instability were present. No signature of magnetic reconnection was observed anywhere in the prominence body and its surroundings. The filament/prominence descent following the eruption and its partial reformation at the same place two days later suggest a confined type of eruption. The asymmetric background magnetic field possibly played an important role in the failed eruption.

Movies showing the temporal evolution are available in electronic form at http://www.aanda.org Title: Solar magnetism eXplorer (SolmeX). Exploring the magnetic field in the upper atmosphere of our closest star Authors: Peter, Hardi; Abbo, L.; Andretta, V.; Auchère, F.; Bemporad, A.; Berrilli, F.; Bommier, V.; Braukhane, A.; Casini, R.; Curdt, W.; Davila, J.; Dittus, H.; Fineschi, S.; Fludra, A.; Gandorfer, A.; Griffin, D.; Inhester, B.; Lagg, A.; Landi Degl'Innocenti, E.; Maiwald, V.; Sainz, R. Manso; Martínez Pillet, V; Matthews, S.; Moses, D.; Parenti, S.; Pietarila, A.; Quantius, D.; Raouafi, N. -E.; Raymond, J.; Rochus, P.; Romberg, O.; Schlotterer, M.; Schühle, U.; Solanki, S.; Spadaro, D.; Teriaca, L.; Tomczyk, S.; Trujillo Bueno, J.; Vial, J. -C. Bibcode: 2012ExA....33..271P Altcode: 2011arXiv1108.5304P; 2011ExA...tmp..134P The magnetic field plays a pivotal role in many fields of Astrophysics. This is especially true for the physics of the solar atmosphere. Measuring the magnetic field in the upper solar atmosphere is crucial to understand the nature of the underlying physical processes that drive the violent dynamics of the solar corona—that can also affect life on Earth. SolmeX, a fully equipped solar space observatory for remote-sensing observations, will provide the first comprehensive measurements of the strength and direction of the magnetic field in the upper solar atmosphere. The mission consists of two spacecraft, one carrying the instruments, and another one in formation flight at a distance of about 200 m carrying the occulter to provide an artificial total solar eclipse. This will ensure high-quality coronagraphic observations above the solar limb. SolmeX integrates two spectro-polarimetric coronagraphs for off-limb observations, one in the EUV and one in the IR, and three instruments for observations on the disk. The latter comprises one imaging polarimeter in the EUV for coronal studies, a spectro-polarimeter in the EUV to investigate the low corona, and an imaging spectro-polarimeter in the UV for chromospheric studies. SOHO and other existing missions have investigated the emission of the upper atmosphere in detail (not considering polarization), and as this will be the case also for missions planned for the near future. Therefore it is timely that SolmeX provides the final piece of the observational quest by measuring the magnetic field in the upper atmosphere through polarimetric observations. Title: Synthetic differential emission measure curves of prominence fine structures. II. The SoHO/SUMER prominence of 8 June 2004 Authors: Gunár, S.; Parenti, S.; Anzer, U.; Heinzel, P.; Vial, J. -C. Bibcode: 2011A&A...535A.122G Altcode:
Aims: This study is the first attempt to combine the prominence observations in Lyman, UV, and EUV lines with the determination of the prominence differential emission measure derived using two different techniques, one based on the inversion of the observed UV and EUV lines and the other employing 2D non-LTE prominence fine-structure modeling of the Lyman spectra.
Methods: We use a trial-and-error method to derive the 2D multi-thread prominence fine-structure model producing synthetic Lyman spectra in good agreement with the observations. We then employ a numerical method to perform the forward determination of the DEM from 2D multi-thread models and compare the synthetic DEM curves with those derived from observations using inversion techniques.
Results: A set of available observations of the June 8, 2004 prominence allows us to determine the range of input parameters, which contains models producing synthetic Lyman spectra in good agreement with the observations. We select three models, which represent this parametric-space area well and compute the synthetic DEM curves for multi-thread realizations of these models. The synthetic DEM curves of selected models are in good agreement with the DEM curves derived from the observations.
Conclusions: We show that the evaluation of the prominence fine-structure DEM complements the analysis of the prominence hydrogen Lyman spectra and that its combination with the detailed radiative-transfer modeling of prominence fine structures provides a useful tool for investigating the prominence temperature structure from the cool core to the prominence-corona transition region. Title: Hydrogen Lyα and Lyβ Radiances and Profiles in Polar Colornal Holes Authors: Tian, Hui; Teriaca, Luca; Curdt, Werner; Vial, Jean-Claude Bibcode: 2011shin.confE.166T Altcode: The hydrogen Lyα plays a dominant role in the radiative energy transport in the lower transition region, and is important for the studies of transition-region structure as well as solar wind origin. We investigate the Lyα profiles obtained by the Solar Ultraviolet Measurement of Emitted Radiation spectrograph on the Solar and Heliospheric Observatory spacecraft in coronal holes and the quiet Sun. In a subset of these observations, the Hi Lyβ, Si III, and Ovi lines were also (quasi-)simultaneously recorded. We find that the distances between the two peaks of Lyα profiles are larger in coronal holes than in the quiet Sun, indicating a larger opacity in coronal holes. This difference might result from the different magnetic structures or the different radiation fields in the two regions. Most of the Lyβ profiles in the coronal hole have a stronger blue peak, in contrast to those in quiet-Sun regions while in both regions the Lyα profiles are stronger in the blue peak. Although the asymmetries are likely to be produced by differential flows in the solar atmosphere, their detailed formation processes are still unclear. The radiance ratio between Lyα and Lyβ decreases toward the limb in the coronal hole, which might be due to the different opacity of the two lines. We also find that the radiance distributions of the four lines are set by a combined effect of limb brightening and the different emission level between coronal holes and the quiet Sun. Title: Automated detection of filaments in SDO data Authors: Buchlin, É.; Mercier, C.; Engin, S.; Parenti, S.; Vial, J. -C. Bibcode: 2010sf2a.conf..297B Altcode: Solar eruption can eject billions of tons of plasma to the interplanetary space, with geophysical effects and impacts on human activities. The time constraints for space weather application as well as the huge volume of data that needs to be analyzed, especially since the launch of SDO, imply that the detection of solar filaments and their eruptions must be automated. Most current detection codes use Hα data, which are not available frequently enough for these applications. We present a new detection code that we have developed at IAS and that uses the high spatial and temporal-resolution SDO/AIA He II 30.4 nm data. Title: Turbulence in the Solar Atmosphere and Solar Wind Authors: Petrosyan, A.; Balogh, A.; Goldstein, M. L.; Léorat, J.; Marsch, E.; Petrovay, K.; Roberts, B.; von Steiger, R.; Vial, J. C. Bibcode: 2010SSRv..156..135P Altcode: 2010SSRv..tmp..117P The objective of this review article is to critically analyze turbulence and its role in the solar atmosphere and solar wind, as well as to provide a tutorial overview of topics worth clarification. Although turbulence is a ubiquitous phenomenon in the sun and its heliosphere, many open questions exist concerning the physical mechanisms of turbulence generation in solar environment. Also, the spatial and temporal evolution of the turbulence in the solar atmosphere and solar wind are still poorly understood. We limit the scope of this paper (leaving out the solar interior and convection zone) to the magnetized plasma that reaches from the photosphere and chromosphere upwards to the corona and inner heliosphere, and place particular emphasis on the magnetic field structures and fluctuations and their role in the dynamics and radiation of the coronal plasma. To attract the attention of scientists from both the fluid-dynamics and space-science communities we give in the first two sections a phenomenological overview of turbulence-related processes, in the context of solar and heliospheric physics and with emphasis on the photosphere-corona connection and the coupling between the solar corona and solar wind. We also discuss the basic tools and standard concepts for the empirical analysis and theoretical description of turbulence. The last two sections of this paper give a concise review of selected aspects of oscillations and waves in the solar atmosphere and related fluctuations in the solar wind. We conclude with some recommendations and suggest topics for future research. Title: Definition of an imaging spectrometer meeting the needs of UV solar physics Authors: Ruiz de Galarreta Fanjul, C.; Philippon, A.; Vial, J. -C.; Lemaire, P.; Maillard, J. -P.; Buisset, C.; Appourchaux, T.; Auchère, F. Bibcode: 2010SPIE.7732E..36R Altcode: 2010SPIE.7732E..99R The study of the outer solar atmosphere requires combining imaging and spectroscopy in the UV lines formed in the high chromosphere, the transition region and the corona. We start from the science requirements and we define the instrumental specifications in terms of field-of-view (FOV), spatial, temporal and spectral resolution and bandpass. We propose two different all-reflection optical architectures based on interferometric techniques: Spatial Heterodyne Spectroscopy (SHS); and Imaging Transform Spectrometer (IFTS). We describe the different set-ups and compare the potential performances of the two types of solutions, and discuss their feasibility. We conclude that IFTS appears to be the best solution, meeting the needs of UV solar physics. However, we point out the many difficulties to be encountered, especially as far as metrology is concerned. Title: Physics of Solar Prominences: I—Spectral Diagnostics and Non-LTE Modelling Authors: Labrosse, N.; Heinzel, P.; Vial, J. -C.; Kucera, T.; Parenti, S.; Gunár, S.; Schmieder, B.; Kilper, G. Bibcode: 2010SSRv..151..243L Altcode: 2010SSRv..tmp...34L; 2010arXiv1001.1620L This review paper outlines background information and covers recent advances made via the analysis of spectra and images of prominence plasma and the increased sophistication of non-LTE ( i.e. when there is a departure from Local Thermodynamic Equilibrium) radiative transfer models. We first describe the spectral inversion techniques that have been used to infer the plasma parameters important for the general properties of the prominence plasma in both its cool core and the hotter prominence-corona transition region. We also review studies devoted to the observation of bulk motions of the prominence plasma and to the determination of prominence mass. However, a simple inversion of spectroscopic data usually fails when the lines become optically thick at certain wavelengths. Therefore, complex non-LTE models become necessary. We thus present the basics of non-LTE radiative transfer theory and the associated multi-level radiative transfer problems. The main results of one- and two-dimensional models of the prominences and their fine-structures are presented. We then discuss the energy balance in various prominence models. Finally, we outline the outstanding observational and theoretical questions, and the directions for future progress in our understanding of solar prominences. Title: Hanle signatures of the coronal magnetic field in the linear polarization of the hydrogen Lα line Authors: Derouich, M.; Auchère, F.; Vial, J. C.; Zhang, M. Bibcode: 2010A&A...511A...7D Altcode: 2009arXiv0912.5068D
Aims: This paper is dedicated to the assessment of the validity of future coronal spectro-polarimetric observations and to prepare their interpretation in terms of the magnetic field vector.
Methods: We assume that the polarization of the hydrogen coronal Lα line is due to anisotropic scattering of an incident chromospheric radiation field. The anisotropy is due to geometrical effects but also to the inhomogeneities of the chromospheric regions which we model by using Carrington maps of the Lα. Because the corona is optically thin, we fully consider the effects of the integration over the line-of-sight (LOS). As a modeling case, we include a dipolar magnetic topology perturbed by a non-dipolar magnetic structure arising from a prominence current sheet in the corona. The spatial variation of the hydrogen density and the temperature is taken into account. We determine the incident radiation field developed on the tensorial basis at each point along the LOS. Then, we calculate the local emissivity vector to obtain integrated Stokes parameters with and without coronal magnetic field.
Results: We show that the Hanle effect is an interesting technique for interpreting the scattering polarization of the Lαλ1216 line in order to diagnose the coronal magnetic field. The difference between the calculated polarization and the zero magnetic field polarization gives us an estimation of the needed polarimetric sensitivity in future polarization observations. We also obtain useful indications about the optimal observational strategy.
Conclusions: Quantitative interpretation of the Hanle effect on the scattering linear polarization of Lα line can be a crucial source of information about the coronal magnetic field at a height over the limb h < 0.7 R. Therefore, one needs the development of spatial instrumentation to observe this line.

Present address: Colorado Research Associates Division, NorthWest Research Associates, Inc., 3380 Mitchell Ln., Boulder, CO 80301, USA. Title: Space solar missions Authors: Vial, Jean-Claude Bibcode: 2010IAUS..264..459V Altcode: In the frame of Symposium 264 which concerns Solar and Stellar Variability we address the space solar missions devoted to the various aspects of solar activity. We describe them in three time categories: missions ready for launch, missions which will operate in the 2012-2015 time frame and ambitious missions to be launched after 2015. We focus on the contributions of these missions according to the following criteria: Understanding mechanisms of activity, Improving detection and characterisation, Working out some prediction. Major activity contributors and manifestations are addressed: Coronal Mass Ejections, Flares, Solar winds, Magnetism (including dynamo), Irradiance. Title: Discussion with the HMI Team representative Authors: Vial, Jean-Claude Bibcode: 2010cosp...38.2865V Altcode: 2010cosp.meet.2865V Discussion with the HMI Team representative after her presentation Title: Automated detection of filaments and their eruptions from AIA and HMI/SDO data Authors: Buchlin, Eric; Mercier, Claude; Vial, Jean-Claude Bibcode: 2010cosp...38.2862B Altcode: 2010cosp.meet.2862B The superior temporal, spatial and spectral range of AIA on SDO provides a completely new view of the dynamic nature of coronal loops. In this paper, we will examine preliminary results of a number of loop examples as their evolution is followed closely in time and space across the AIA filters. The implications of these observational results on the heating and cooling mechanisms operating will be discussed. 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 Bibcode: 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: Discussion with EVE PI Authors: Vial, Jean-Claude Bibcode: 2010cosp...38.2872V Altcode: 2010cosp.meet.2872V Discussion with EVE PI after his presentation Title: Large-scale Extreme-Ultraviolet Disturbances Associated with a Limb Coronal Mass Ejection Authors: Dai, Y.; Auchère, F.; Vial, J. -C.; Tang, Y. H.; Zong, W. G. Bibcode: 2010ApJ...708..913D Altcode: We present composite observations of a coronal mass ejection (CME) and the associated large-scale extreme-ultraviolet (EUV) disturbances on 2007 December 31 by the Extreme-ultraviolet Imager (EUVI) and COR1 coronagraph on board the recent Solar Terrestrial Relations Observatory mission. For this limb event, the EUV disturbances exhibit some typical characteristics of EUV Imaging Telescope waves: (1) in the 195 Å bandpass, diffuse brightenings are observed propagating oppositely away from the flare site with a velocity of ~260 km s-1, leaving dimmings behind; (2) when the brightenings encounter the boundary of a polar coronal hole, they stop there to form a stationary front. Multi-temperature analysis of the propagating EUV disturbances favors a heating process over a density enhancement in the disturbance region. Furthermore, the EUVI-COR1 composite display shows unambiguously that the propagation of the diffuse brightenings coincides with a large lateral expansion of the CME, which consequently results in a double-loop-structured CME leading edge. Based on these observational facts, we suggest that the wave-like EUV disturbances are a result of magnetic reconfiguration related to the CME liftoff rather than true waves in the corona. Reconnections between the expanding CME magnetic field lines and surrounding quiet-Sun magnetic loops account for the propagating diffuse brightenings; dimmings appear behind them as a consequence of volume expansion. X-ray and radio data provide us with complementary evidence. Title: Discussion with AIA PI Authors: Vial, Jean-Claude Bibcode: 2010cosp...38.2860V Altcode: 2010cosp.meet.2860V Discussion with the PI after his presentation Title: Poster session Authors: Vial, Jean-Claude Bibcode: 2010cosp...38.2870V Altcode: 2010cosp.meet.2870V Poster presentation Title: Hydrogen Lyα and Lyβ Radiances and Profiles in Polar Coronal Holes Authors: Tian, Hui; Teriaca, Luca; Curdt, Werner; Vial, Jean-Claude Bibcode: 2009ApJ...703L.152T Altcode: 2009arXiv0909.0735T The hydrogen Lyα plays a dominant role in the radiative energy transport in the lower transition region, and is important for the studies of transition-region structure as well as solar wind origin. We investigate the Lyα profiles obtained by the Solar Ultraviolet Measurement of Emitted Radiation spectrograph on the Solar and Heliospheric Observatory spacecraft in coronal holes and the quiet Sun. In a subset of these observations, the H I Lyβ, Si III, and O VI lines were also (quasi-)simultaneously recorded. We find that the distances between the two peaks of Lyα profiles are larger in coronal holes than in the quiet Sun, indicating a larger opacity in coronal holes. This difference might result from the different magnetic structures or the different radiation fields in the two regions. Most of the Lyβ profiles in the coronal hole have a stronger blue peak, in contrast to those in quiet-Sun regions while in both regions the Lyα profiles are stronger in the blue peak. Although the asymmetries are likely to be produced by differential flows in the solar atmosphere, their detailed formation processes are still unclear. The radiance ratio between Lyα and Lyβ decreases toward the limb in the coronal hole, which might be due to the different opacity of the two lines. We also find that the radiance distributions of the four lines are set by a combined effect of limb brightening and the different emission level between coronal holes and the quiet Sun. Title: Solar source of energetic particles in interplanetary space during the 2006 December 13 event Authors: Li, C.; Dai, Y.; Vial, J. -C.; Owen, C. J.; Matthews, S. A.; Tang, Y. H.; Fang, C.; Fazakerley, A. N. Bibcode: 2009A&A...503.1013L Altcode: 2013arXiv1305.5593L An X3.4 solar flare and a fast halo coronal mass ejection (CME) occurred on 2006 December 13, accompanied by a high flux of energetic particles recorded both in near-Earth space and at ground level. Our purpose is to provide evidence of flare acceleration in a major solar energetic particle (SEP) event. We first present observations from ACE/EPAM, GOES, and the Apatity neutron monitor. It is found that the initial particle release time coincides with the flare emission and that the spectrum becomes softer and the anisotropy becomes weaker during particle injection, indicating that the acceleration source changes from a confined coronal site to a widespread interplanetary CME-driven shock. We then describe a comprehensive study of the associated flare active region. By use of imaging data from HINODE/SOT and SOHO/MDI magnetogram, we infer the flare magnetic reconnection rate in the form of the magnetic flux change rate. This correlates in time with the microwave emission, indicating a physical link between the flare magnetic reconnection and the acceleration of nonthermal particles. Combining radio spectrograph data from Huairou/NOAC, Culgoora/IPS, Learmonth/RSTN, and WAVES/WIND leads to a continuous and longlasting radio burst extending from a few GHz down to several kHz. Based on the photospheric vector magnetogram from Huairou/NOAC and the nonlinear force free field (NFFF) reconstruction method, we derive the 3D magnetic field configuration shortly after the eruption. Furthermore, we also compute coronal field lines extending to a few solar radii using a potential-field source-surface (PFSS) model. Both the so-called type III-l burst and the magnetic field configuration suggest that open-field lines extend from the flare active region into interplanetary space, allowing the accelerated and charged particles escape. Title: Electron density in the quiet solar coronal transition region from SoHO/SUMER measurements of S VI line radiance and opacity Authors: Buchlin, E.; Vial, J. -C. Bibcode: 2009A&A...503..559B Altcode: 2009arXiv0906.1367B Context: The steep temperature and density gradients that are measured in the coronal transition region challenge the model interpretation of observations.
Aims: We derive the average electron density < ne > in the region emitting the S vi lines. We use two different techniques, which allow us to derive linearly-weighted (opacity method) and quadratically-weighted (emission measure method) electron density along the line-of-sight, to estimate a filling factor or derive the layer thickness at the formation temperature of the lines.
Methods: We analyze SoHO/SUMER spectroscopic observations of the S vi lines, using the center-to-limb variations in radiance, the center-to-limb ratios of radiance and line width, and the radiance ratio of the 93.3-94.4 nm doublet to derive the opacity. We also use the emission measure derived from radiance at disk center.
Results: We derive an opacity τ0 at S vi 93.3 nm line center of the order of 0.05. The resulting average electron density < {ne}>, under simple assumptions concerning the emitting layer, is 2.4 × 1016 m-3 at T = 2 × 105 K. This value is higher than (and inconsistent with) the values obtained from radiance measurements (2 × 1015 m-3). The last value corresponds to an electron pressure of 10-2 Pa. Conversely, taking a classical value for the density leads to a too high value of the thickness of the emitting layer.
Conclusions: The pressure derived from the emission measure method compares well with previous determinations. It implies a low opacity of between 5 × 10-3 and 10-2. It remains unexplained why a direct derivation leads to a much higher opacity, despite tentative modeling of observational biases. Further measurements in S vi and other lines emitted at a similar temperature should be completed, and more realistic models of the transition region need to be used. Title: The He II Lines in the Lyman Series Profiles of Solar Prominences Authors: Ebadi, H.; Vial, J. -C.; Ajabshirizadeh, A. Bibcode: 2009SoPh..257...91E Altcode: The hydrogen and helium lines are the most prominent lines in the solar prominences spectra. Observations with the SUMER spectrometer onboard SOHO showed that there are weak lines in the blue wings of the Lyman series which affect their profiles. They were all identified as He II lines in the Lyman series wings, except for the Lα line whose profile was affected by the use of an attenuator. The He II lines are the even Balmer lines of the He II system, a set of lines that we complete with the odd ones. We characterize them by comparison with the blue wings of the Lyman series in order to improve the H Lyman series observations and modeling, on one hand and to provide He II lines observations for further combined H - He I - He II modeling, on the other hand. Title: Polarimetry of the Lα Line for Coronal Magnetic Field Diagnostic Authors: Derouich, M.; Auchère, F.; Vial, J. C.; Millard, A. A. Bibcode: 2009ASPC..405..389D Altcode: Measurement and physical interpretation of the scattering polarization of the Extreme-ultraviolet (EUV) and Far-UV (FUV) spectral lines provide a largely unexplored diagnostic of coronal magnetic field. In this context, we present the LYOT (LYman Orbiting Telescope) project that makes it possible to observe the Lα λ1216 line polarization in the solar corona. Because the corona is optically thin, it is necessary to consider the effects of the integration over the line-of-sight (LOS). The LOS effects have been usually addressed for non polarimetric studies where the unknown is a scalar quantity (the intensity) but not a Stokes vector. Previous studies investigating the coronal polarization are generally concerned with a local position of the scattering center and a deterministic magnetic field (see Raouafi et al.~2002 for a measurement and interpretation of the O VI λ 1032 line polarization). Here, we perform computations that test whether a LOS integrated Hanle effect can be detected in order to access to the magnetic field topology. Title: Diagnostics of active and eruptive prominences through hydrogen and helium lines modelling Authors: Labrosse, N.; Vial, J. -C.; Gouttebroze, P. Bibcode: 2008AnGeo..26.2961L Altcode: 2008arXiv0804.4625L In this study we show how hydrogen and helium lines modelling can be used to make a diagnostic of active and eruptive prominences. One motivation for this work is to identify the physical conditions during prominence activation and eruption. Hydrogen and helium lines are key in probing different parts of the prominence structure and inferring the plasma parameters. However, the interpretation of observations, being either spectroscopic or obtained with imaging, is not straightforward. Their resonance lines are optically thick, and the prominence plasma is out of local thermodynamic equilibrium due to the strong incident radiation coming from the solar disk. In view of the shift of the incident radiation occuring when the prominence plasma flows radially, it is essential to take into account velocity fields in the prominence diagnostic. Therefore we need to investigate the effects of the radial motion of the prominence plasma on hydrogen and helium lines. The method that we use is the resolution of the radiative transfer problem in the hydrogen and helium lines out of local thermodynamic equilibrium. We study the variation of the computed integrated intensities in H and He lines with the radial velocity of the prominence plasma. We can confirm that there exist suitable lines which can be used to make a diagnostic of the plasma in active and eruptive prominences in the presence of velocity fields. Title: The Lyman-alpha Line in Active and Eruptive Solar Prominences Authors: Labrosse, N.; Vial, J. -C. Bibcode: 2008ESPM...12.3.17L Altcode: We investigate the effects of radial motions on the Ly-alpha emission in moving prominences under various temperature and pressure conditions and for various prominence masses. The ability to compute the Ly-alpha line intensity in active and erupting prominences with our non-LTE radiative transfer code is especially relevant to VAULT and to the LYOT instrument on SMESE. In the case of erupting prominences, high-cadence imaging as anticipated from LYOT/SMESE, will allow us to observe the dimming of the line as the prominence expands in the radial direction. In conjunction with our non-LTE radiative transfer code, the diagnostic of the thermodynamical plasma parameters and the velocity field can be done. This should provide new constraints for models of filament and prominence eruptions. Title: Properties of the quiet solar coronal transition region from full-Sun SoHO/SUMER S VI Authors: Buchlin, E.; Vial, J. Bibcode: 2008ESPM...122.117B Altcode: A series of full-Sun SoHO/SUMER observations of the quiet Sun in the transition region lines S VI 933 and 944 (as well as Ly epsilon) has been performed during year 1996. We use this unique data set to derive the opacity of the S VI lines by different methods (following Dumont et al. 1983), taking advantage from the availability of full-Sun data and

of the S VI doublet: 1. using the center-to-limb variations of S VI 933 radiance and peak spectral radiance, 2. using the center-to-limb variations of S VI 933 line width and radiance, and 3. using the S VI 944 - 933 radiance or spectral radiance ratio at disk center. We then deduce an average value for the density in the S VI emitting region (in the coronal transition region). By comparing this value to the average square density obtained by an Emission Measure analysis, we get a tentative estimate of the filling factor in this region. Title: The HeII (and DI) Lines in the Lyman Series of Solar Prominences Authors: Vial, J. -C.; Ebadi, H.; Ajabshirizadeh, A. Bibcode: 2008ESPM...12.2.20V Altcode: The hydrogen lines are the most prominent lines in solar prominence spectra. Observations with the SUMER spectrometer on board SoHO showed that there are weak emission lines in the blue wings of the Lyman series which affect their profiles. We identified them as D I and He II lines in the Lyman alpha profile and He II lines in the upper Lyman series wings. The He II lines are identified as Balmer lines of He II. We attempt to characterize these lines in the blue wings of the Lyman series and consequently to provide supplementary He II information for further He I-He II non-LTE modelling. Title: Developing a CME-Associated Phenomena Catalog for SDO Authors: Wills-Davey, M. J.; Davey, A. R.; Vial, J. Bibcode: 2008AGUSMSP51B..12W Altcode: With the anticipated launch of the Solar Dynamics Observatory (SDO), we have embarked on the development of an automated detection scheme which will correlate and catalog CME-associated phenomena with CME observations from existing coronagraphs. Observing primarily using the Atmospheric Imaging Assembly (AIA), the SDO CME catalog will focus on various aspects of CME initiation and development, including automated measurement of coronal dimming regions at CME onset, the detection of filament eruptions in near-real time, and the automated tracking of CME fronts in coronagraph data. Title: A Time-Evolving 3D Method Dedicated to the Reconstruction of Solar Plumes and Results Using Extreme Ultraviolet Data Authors: Barbey, Nicolas; Auchère, Frédéric; Rodet, Thomas; Vial, Jean-Claude Bibcode: 2008SoPh..248..409B Altcode: 2008SoPh..tmp...65B; 2008arXiv0802.0113B An important issue in the tomographic reconstruction of the solar poles is the relatively rapid evolution of the polar plumes. We demonstrate that it is possible to take into account this temporal evolution in the reconstruction. The difficulty of this problem comes from the fact that we want a four-dimensional reconstruction (three spatial dimensions plus time) whereas we only have three-dimensional data (two-dimensional images plus time). To overcome this difficulty, we introduce a model that describes polar plumes as stationary objects whose intensity varies homogeneously with time. This assumption can be physically justified if one accepts the stability of the magnetic structure. This model leads to a bilinear inverse problem. We describe how to extend linear inversion methods to these kinds of problems. Studies of simulations show the reliability of our method. Results for SOHO/EIT data show that we can estimate the temporal evolution of polar plumes to improve the reconstruction of the solar poles from only one point of view. We expect further improvements from STEREO/EUVI data when the two probes will be separated by about 60°. Title: Polarisation and magnetic depolarization of the Lyman-alpha line in the corona : the line-of-sight effects Authors: Vial, Jean-Claude; Derouich, Moncef; Auchere, Frederic; Zhang, Mei Bibcode: 2008cosp...37.3340V Altcode: 2008cosp.meet.3340V In view of the importance of measuring coronal magnetic field and of the capability of measuring linear polarization in the Lyman α line with the LYOT coronagraph on board the SMESE mission, we carried out some calculations of the degrees of depolarization resulting from the presence of a magnetic field. Our calculation is based on a simple magnetic field model where a current sheet in the field represents a solar prominence. We focus in this study on the effect of the line-of-sight integration at various locations in the corona on the polarizing/depolarizing properties. Other magnetic configurations are also considered and are under the study. Title: Solar prominence properties derived from the UV-EUV SUMER spectral atlas Authors: Parenti, S.; Vial, J. -C.; Lemaire, P. Bibcode: 2008AdSpR..41..144P Altcode: In this paper, we summarize the work done to build a UV-EUV spectral atlas of a prominence and we introduce some recent scientific results obtained from these data. For this work we used SOHO/SUMER data covering the full wavelength range accessible by the instrument (from about 800 to 1600 Å), when a prominence and the quiet Sun (used as spectral reference) were observed in October 1998. We present here only a fraction of the data, which results in the analysis of more than 600 spectral lines, including some new identifications. Here we also present the differential emission measure obtained from the data, both for the quiet Sun and the prominence. The main differences in characteristics are discussed. Title: The Reversal Behavior of Some Hydrogen Lyman Lines in Solar Spicules Authors: Ajabshirizadeh, Ali; Ajabshirizadeh, Ali; Vial, Jean-Claude; Fathi-Vavsari, Hassan; Ebadi, Hossein Bibcode: 2008cosp...37...42A Altcode: 2008cosp.meet...42A Spicules are the dominant component of the quiet solar chromosphere. At the solar limb they appear as jet-like dynamic structures extending into the solar corona. The physical processes that generate spicules have not yet been uniquely identified. In this work, we analyze spicules data taken by the SUMER spectrometer on-board SoHO in the Lyman Beta and Lyman Gamma lines. A similar analysis has been done already by Vial et al. (2007) in Lyman alpha and Lyman beta lines. The data used have a spatial resolution of one arcsec along the slit and a spectral resolution of about 44 mA. We applied the standard procedures for geometric distortion, flat- fielding and dead time corrections, which can be found in the Solar Software (SSW) database. Our results show that in spicules both Lyman beta and Lyman gamma line profiles are reversed at all altitudes; on the contrary, in the prominence, the Lyman beta and Lyman gamma line profiles are reversed only at higher altitude, while at lower altitude they are clearly non-reversed in accordance with Vial et al. (2007). We provide some explanation for this behavior. Title: SMESE (SMall Explorer for Solar Eruptions): A microsatellite mission with combined solar payload Authors: Vial, J. -C.; Auchère, F.; Chang, J.; Fang, C.; Gan, W. Q.; Klein, K. -L.; Prado, J. -Y.; Rouesnel, F.; Sémery, A.; Trottet, G.; Wang, C. Bibcode: 2008AdSpR..41..183V Altcode: The SMESE (SMall Explorer for Solar Eruptions) mission is a microsatellite proposed by France and China. The payload of SMESE consists of three packages: LYOT (a Lyman α imager and a Lyman α coronagraph), DESIR (an Infra-red Telescope working at 35 80 and 100 250 μm), and HEBS (a High Energy Burst Spectrometer working in X- and gamma-rays). The scientific objectives of the mission are shortly presented. We describe the three instrumental packages and the profile of the mission which accommodates them. With a launch around 2012 2013, the SMESE microsatellite mission will provide a unique tool for detecting and understanding eruptions (flares and coronal mass ejections). Observations should start around solar maximum, and continue in the declining phase of activity, at a time when the Solar Dynamics Observatory (SDO) should still be operating. Title: The Ly α and Ly β Profiles in Solar Prominences and Prominence Fine Structure Authors: Vial, J. -C.; Ebadi, H.; Ajabshirizadeh, A. Bibcode: 2007SoPh..246..327V Altcode: 2007arXiv0710.1433V Ly α and Ly β line profiles in a solar prominence were observed with high spatial and spectral resolution with SOHO/SUMER. Within a 60-arcsec scan, we measure a very large variety of profiles: not only reversed and nonreversed profiles but also red-peaked and blue-peaked ones in both lines. Such a spatial variability is probably related to both the fine structure in prominences and the different orientations of mass motions. The usage of integrated-intensity cuts along the SUMER slit allowed us to categorize the prominence in three regions. We computed average profiles and integrated intensities in these lines in the range 2.36 - 42.3 W m−2 sr−1 for Ly α and 0.027 - 0.237 W m−2 sr−1 for Ly β. As shown by theoretical modeling, the Ly α/Ly β ratio is very sensitive to geometrical and thermodynamic properties of fine structure in prominences. For some pixels, and in both lines, we found agreement between observed intensities and those predicted by one-dimensional models. But a close examination of the profiles indicated a rather systematic disagreement concerning their detailed shapes. The disagreement between observations and thread models (with ambipolar diffusion) leads us to speculate about the importance of the temperature gradient between the cool and coronal regions. This gradient could depend on the orientation of field lines as proposed by Heinzel, Anzer, and Gunár (Astron. Astrophys.442, 331, 2005). Title: Flare magnetic reconnection and relativistic particles in the 2003 October 28 event Authors: Li, C.; Tang, Y. H.; Dai, Y.; Fang, C.; Vial, J. -C. Bibcode: 2007A&A...472..283L Altcode: 2007arXiv0706.3648L An X17.2 solar flare occurred on 2003 October 28, accompanied by multi-wavelength emissions and a high flux of relativistic particles observed at 1 AU. We present the analytic results of the TRACE, SOHO, RHESSI, ACE, GOES, hard X-ray (INTEGRAL satellite), radio (Ondeřejov radio telescope), and neutron monitor data. It is found that the inferred magnetic reconnection electric field correlates well with the hard X-ray, gamma-ray, and neutron emission at the Sun. Thus the flare's magnetic reconnection probably makes a crucial contribution to the prompt relativistic particles, which could be detected at 1 AU. Since the neutrons were emitted a few minutes before the injection of protons and electrons, we propose a magnetic-field evolution configuration to explain this delay. We do not exclude the effect of CME-driven shock, which probably plays an important role in the delayed gradual phase of solar energetic particles. Title: Prominence and quiet-Sun plasma parameters derived from FUV spectral emission Authors: Parenti, S.; Vial, J. -C. Bibcode: 2007A&A...469.1109P Altcode: Context: A solar prominence and the quiet-Sun (QS) were observed with SOHO/SUMER in October 1999. With this dataset we built the first comprehensive UV spectral atlas in the range 800-1250 Å for a prominence, thus complementing the existing reference atlases for the QS.
Aims: This is a detailed study based on the information in this atlas, with the aim of deriving the plasma parameters in two distinct regions. The large amount of information available allows us to establish these parameters with lower uncertainty than in previous studies, leading to reference values for theoretical investigations.
Methods: The measured lines' FWHM were used to derive the distribution of the non-thermal velocities at various temperatures. The lines intensities were used to derive the electron densities at temperatures of 7 × 104 K and the differential emission measure.
Results: The comparison with the QS shows lower velocities in the prominence for temperature T with log~T < 5.4. The velocities derived in the highest part of the prominence show a lower gradient with the temperature. The value obtained for the electron density indicates a low pressure prominence. We conclude with a discussion of the energy budget in the prominence.

Table 1 is only available in electronic form at http://www.aanda.org Title: Spectral Diagnostics of Active Prominences Authors: Labrosse, N.; Gouttebroze, P.; Vial, J. -C. Bibcode: 2007ASPC..368..337L Altcode: 2006astro.ph.11488L Active prominences exhibit plasma motions, resulting in difficulties with the interpretation of spectroscopic observations. These solar features being strongly influenced by the radiation coming from the solar disk, Doppler dimming or brightening effects may arise, depending on which lines are observed and on the velocity of the plasma. Interlocking between the different atomic energy levels and non local thermodynamic equilibrium lead to non-trivial spectral line profiles, and this calls for complex numerical modeling of the radiative transfer in order to understand the observations. We present such a tool, which solves the radiative transfer and statistical equilibrium for H, He I, He II, and Ca II in moving prominences where radial plasma motions are taking place. It is found that for isothermal, isobaric prominence models, the He II resonance lines are very sensitive to the Doppler effect and thus show a strong Doppler dimming. The Ca II lines Doppler effect for the prominence models considered here. We illustrate how the code makes it possible to retrieve the plasma thermodynamic parameters by comparing computed and observed line profiles of hydrogen and helium resonance lines in a quiescent prominence. This new non-LTE radiative transfer code including velocities allows us to better understand the formation of several lines of importance in prominences, and in conjunction with observations, infer the prominence plasma thermodynamic properties and full velocity vector. Title: Effect of motions in prominences on the helium resonance lines in the extreme ultraviolet Authors: Labrosse, N.; Gouttebroze, P.; Vial, J. -C. Bibcode: 2007A&A...463.1171L Altcode: 2006astro.ph..8221L Context: Extreme ultraviolet resonance lines of neutral and ionised helium observed in prominences are difficult to interpret as the prominence plasma is optically thick at these wavelengths. If mass motions are taking place, as is the case in active and eruptive prominences, the diagnostic is even more complex.
Aims: We aim at studying the effect of radial motions on the spectrum emitted by moving prominences in the helium resonance lines and at facilitating the interpretation of observations, in order to improve our understanding of these dynamic structures.
Methods: We develop our non-local thermodynamic equilibrium radiative transfer code formerly used for the study of quiescent prominences. The new numerical code is now able to solve the statistical equilibrium and radiative transfer equations in the non-static case by using velocity-dependent boundary conditions for the solution of the radiative transfer problem. This first study investigates the effects of different physical conditions (temperature, pressure, geometrical thickness) on the emergent helium radiation.
Results: The motion of the prominence plasma induces a Doppler dimming effect on the resonance lines of He I and He II. The velocity effects are particularly important for the He II λ 304 Å line as it is mostly formed by resonant diffusion of incident radiation under prominence conditions. The He I resonance lines at 584 and 537 Å also show some sensitivity to the motion of the plasma, all the more when thermal emission is not too important in these lines. We also show that it is necessary to consider partial redistribution in frequency for the scattering of the incident radiation.
Conclusions: .This set of helium lines offers strong diagnostic possibilities that can be exploited with the SOHO spectrometers and with the EIS spectrometer on board the Hinode satellite. The addition of other helium lines and of lines from other elements (in particular hydrogen) in the diagnostics will further enhance the strength of the method.

Figures [see full text], [see full text] and [see full text] are only available in electronic form at http://www.aanda.org 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. Bibcode: 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 τ500=1. Oscillations in lines originating at similar altitudes exhibit different behaviors which we discuss in terms of the formation of the lines. Title: Coronal Turbulence And Intermittency From Solar Orbiter Observations Authors: Buchlin, É.; Vial, J. -C. Bibcode: 2007ESASP.641E..23B Altcode: Turbulent motions and magnetic fields are a key component of coronal heating mechanisms. They are indeed likely to produce the small scales at which the mechanisms such as reconnection are efficient enough. The properties of turbulence (and the associated intermit- tency) may thus have an influence on the energy dissipation in the corona, and need to be characterized from observations. Although turbulence is omnipresent from the Sun to the heliosphere, good observations of MHD turbulence have not yet been performed in the corona, in lines emitted at high temperature, where the heating actually occurs. We propose a study of coordinated EUS- EUI-VIM observations, with better resolution and counting statistics than ever before, whose main goal is to get and interpret the spatial statistics (spectra and structure functions) of the velocity field in lines emitted at high temperatures (log10 T ≥ 6.4), together with the plasma and magnetic environment of the observed region. These statistics will help us understand the precise role of coronal turbulence in the coronal heating processes. Title: SMESE: A SMall Explorer for Solar Eruptions Authors: Vial, J. -C.; Auchère, F.; Chang, J.; Fang, C.; Gan, W. Q.; Klein, K. -L.; Prado, J. -Y.; Trottet, G.; Wang, C.; Yan, Y. H. Bibcode: 2007AdSpR..40.1787V Altcode: The SMall Explorer for Solar Eruptions (SMESE) mission is a microsatellite proposed by France and China. The payload of SMESE consists of three packages: LYOT (a Lyman α imager and a Lyman α coronagraph), DESIR (an Infra-Red Telescope working at 35-80 and 100-250 μm), and HEBS (a High-Energy Burst Spectrometer working in X- and γ-rays). The status of research on flares and coronal mass ejections is briefly reviewed in the context of on-going missions such as SOHO, TRACE and RHESSI. The scientific objectives and the profile of the mission are described. With a launch around 2012-2013, SMESE will provide a unique tool for detecting and understanding eruptions (flares and coronal mass ejections) close to the maximum phase of activity. Title: EUI, The Ultraviolet Imaging Telescopes Of Solar Orbiter Authors: Hochedez, J. -F.; Appourchaux, T.; Defise, J. -M.; Harra, L. K.; Schühle, U.; Auchère, F.; Curdt, W.; Hancock, B.; Kretzschmar, M.; Lawrence, G.; Leclec'h, J. -C.; Marsch, E.; Mercier, R.; Parenti, S.; Podladchikova, E.; Ravet, M. -F.; Rochus, P.; Rodriguez, L.; Rouesnel, F.; Solanki, S.; Teriaca, L.; Van Driel, L.; Vial, J. -C.; Winter, B.; Zhukov, A. Bibcode: 2007ESASP.641E..33H Altcode: The scientific objectives of Solar Orbiter rely ubiquitously on EUI, its suite of solar atmosphere imaging telescopes. In the configuration discussed here, EUI includes three co-aligned High Resolution Imagers (HRI) and one Full Sun Imager (FSI). FSI and two HRIs observe in extreme ultraviolet passbands, dominated by coronal emission. Another HRI is designed for the hydrogen Lyman α radiation in the far UV, imaging the Chromosphere and the lower Transition Region. The current EUI design and some of its development challenges are highlighted. EUI profits from co-rotation phases, solar proximity and departure from the ecliptic. In synergy with the other S.O. payload, EUI probes the dynamics of the solar atmosphere, provides context data for all investigations and helps to link in-situ and remote-sensing observations. In short, it serves all four top-level goals of the mission. For these reasons, the EUI suite is keenly anticipated in the European scientific community and beyond. Title: Modeling the Radiative Signatures of Turbulent Heating in Coronal Loops Authors: Parenti, S.; Buchlin, E.; Cargill, P. J.; Galtier, S.; Vial, J. -C. Bibcode: 2006ApJ...651.1219P Altcode: The statistical properties of the radiative signature of a coronal loop subject to turbulent heating obtained from a three-dimensional (3D) magnetohydrodynamics (MHD) model are studied. The heating and cooling of a multistrand loop is modeled and synthetic spectra for Fe XII 195.12, Fe XV 284.163, and Fe XIX 1118.06 Å are calculated, covering a wide temperature range. The results show that the statistical properties of the thermal and radiative energies partially reflect those of the heating function in that power-law distributions are transmitted, but with very significant changes in the power-law indices. There is a strong dependence on the subloop geometry. Only high-temperature radiation (~107 K) preserves reasonably precise information on the heating function. Title: The Helium Spectrum in Erupting Solar Prominences Authors: Labrosse, N.; Vial, J. C.; Gouttebroze, P. Bibcode: 2006IAUJD...3E..47L Altcode: 2006astro.ph..9511L Even quiescent solar prominences may become active and sometimes erupt. These events are occasionally linked to coronal mass ejections. However we know very little about the plasma properties during the activation and eruption processes. We present the first computations of the helium line profiles emitted by an eruptive prominence. We follow the approach of Gontikakis et al. (1997) who computed the hydrogen spectrum in moving prominences. The prominence is modelled as a plane-parallel slab standing vertically above the solar surface and moving upward as a solid body. The helium spectrum is computed with a non local thermodynamic equilibrium radiative transfer code. The effect of Doppler dimming / brightening is investigated in the resonance lines of He I and He II formed in the EUV, as well as on the He I 10830 Å and He I 5876 Å lines. We focus on the line profile properties and the resulting integrated intensities. We also study the effect of frequency redistribution in the formation mechanisms of the resonance lines. It is shown that the helium lines are very sensitive to Doppler dimming effects. Together with the hydrogen lines they offer the possibility of a powerful diagnostic of the active and eruptive prominence plasma. We discuss the results in view of observations provided by SOHO, and by the upcoming EUS spectrometer on SOLAR-B. Title: What We Have Learned about Prominences and Filaments from SOHO/SUMER and CDS Spectral Observations Authors: Heinzel, P.; Schmieder, B.; Vial, J. -C. Bibcode: 2006ESASP.617E..65H Altcode: 2006soho...17E..65H No abstract at ADS 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 Bibcode: 2006ESASP.617E..82B Altcode: 2006soho...17E..82B No abstract at ADS Title: Looking for Signature of Coronal Heating in the Radiative Emission of a Coronal Loop Authors: Parenti, S.; Buchlin, E.; Cargill, P. J.; Caltier, S.; Vial, J. -C. Bibcode: 2006ESASP.617E.104P Altcode: 2006soho...17E.104P No abstract at ADS Title: The Pending Issue of the Solar Fine Structure of Prominences Authors: Vial, J. -C. Bibcode: 2006ESASP.617E.163V Altcode: 2006soho...17E.163V No abstract at ADS Title: The Helium Spectrum in Moving Solar Prominences Authors: Labrosse, N.; Gouttebroze, P.; Vial, J. -C. Bibcode: 2006ESASP.617E.134L Altcode: 2006soho...17E.134L No abstract at ADS Title: SMESE: a combined UV-IR-X-gamma solar mission Authors: Millard, Anne A.; Auchere, Frederic; Fang, Cheng; Gan, Weiqun; Molodij, Guillaume; Prado, Jean-Yves; Rouesnel, Frederic; Semery, Alain; Trottet, Gerard; Vial, Jean-Claude; Yan, Yihua; Wu, Ji Bibcode: 2006SPIE.6266E..0JM Altcode: 2006SPIE.6266E..15M SMESE (SMall Explorer For the study of Solar Eruptions) is a Franco-Chinese microsatellite mission. The scientific objectives of SMESE are the study of coronal mass ejections and flares. Its payload consists of three instrument packages : LYOT, DESIR and HEBS. LYOT is composed of a Lyman α (121.6 nm) coronagraph, a Lyman α disk imager and a far UV disk imager. DESIR is an infrared telescope working at 35 μm and 150 μm. HEBS is a high energy burst spectrometer working in X rays and γ rays covering the 10 keV to 600 MeV range. SMESE will be launched around 2011, providing a unique opportunity of detecting and understanding eruptions at the maximum activity phase of the solar cycle in a wide range of energies. The instrumentation on board SMESE is described in this paper. Title: IFTSUV: an imaging Fourier transform spectrometer in UV for the next solar space missions Authors: Millard, Anne A.; Lemaire, Philippe; Vial, Jean-Claude Bibcode: 2006SPIE.6266E..2GM Altcode: 2006SPIE.6266E..72M The study of the Sun in the UV spectral domain is essential for a better understanding of the physical processes taking place in the solar atmosphere. The main tools for this study are imagers and spectrometers. Nevertheless, the analysis of imagery data is rapidly limited unless spectral information is available, and the association of spectrometers and imagers is limited by the lack of coherence between the instruments. Therefore, the design of an imaging spectrometer in UV is a priority for solar physicists. In the far UV, only all reflective optical systems can be used thus an imaging Fourier transform spectrometer (IFTS) is the ideal candidate for the realization of such an instrument. The performances of an IFTS are given by the modulation efficiency. Theoretical study of performances and scientific objectives lead to technical and operating specifications. A mock-up of an IFTSUV has been built at IAS to validate the working principle. Its optical design and alignment are described in this paper. The first results are shown and discussed. Planned modifications of the design are also discussed. Title: Plasma diagnostic of a solar prominence from hydrogen and helium resonance lines Authors: Labrosse, N.; Vial, J. -C.; Gouttebroze, P. Bibcode: 2006sf2a.conf..549L Altcode: 2006astro.ph..9643L We present the first comparison of profiles of H et He resonance lines observed by SUMER with theoretical profiles computed with our non-LTE radiative transfer code. We use the HI Lyman β, HI Lyman ɛ, and He I λ 584 Å lines. Our code allows us to obtain the plasma parameters in prominences in conjunction with a multi-line, multi-element set of observations. The plasma temperature in the prominence core is ∼ 8600 K and the pressure is 0.03 dyn cm-2. The Lyβ line is formed in a higher temperature region (more than 11,000 K). Title: A statistical study of SUMER spectral images: events, turbulence, and intermittency Authors: Buchlin, E.; Vial, J. -C.; Lemaire, P. Bibcode: 2006A&A...451.1091B Altcode: 2005astro.ph.11042B We analyze a series of full-Sun observations performed with the SoHO/SUMER instrument between March and October 1996. Some parameters (radiance, shift and width) of the S vi 93.3 nm , S vi 94.4 nm , and Ly \varepsilon line profiles were computed on board. Radiances and line-of-sight velocities in a large central region of the Sun are studied statistically: distributions of solar structures, field Fourier spectra and structure functions are obtained. The structures have distributions with power-law tails, the Fourier spectra of the radiance fields also display power laws, and the normalized structure functions of the radiance and velocity fields increase at small scales. These results support the idea of the existence of small scales, created by turbulence, and of intermittency of the observed fields. These properties may provide insight into the processes needed for heating the transition region, or, if confirmed in the corona, the corona itself. The difficulties encountered in this analysis, especially for the velocity data, underline the need for sensitive ultraviolet imaging spectrometers. Title: New perspectives on prominences as observed by SOHO/SUMER Authors: Schmieder, B.; Vial, J. -C.; Heinzel, P. Bibcode: 2006sf2a.conf..563S Altcode: We summarize the results of our prominence and filament studies based on extensive spectral observations with SOHO/SUMER and CDS instruments. During the past decade we have gathered several sets of UV and EUV spectral data, containing various emission lines of different species. Our main objective was to better understand the formation of hydrogen Lyman lines and continuum (using the results of complex non-LTE transfer simulations). However we have also analysed also UV and EUV lines formed under transition-region and coronal conditions. Some highlights of our studies are: reproduction of Lyman-line profiles with partial redistribution, understanding the role of prominence-corona interface in the formation of Lyman-line cores, establishing the effect of the magnetic-field orientation on the shape of Lyman lines, discovery of EUV filament extensions (invisible in the Hα line) and their explanation, reconstruction of a 3D topology of the filament using EUV coronal lines, temperature diagnostics based on measurements of the hydrogen Lyman continuum, proper explanation of a prominence darkening detected in coronal lines. Title: A New Way to look at Observations with EGSO Authors: Aboudarham, J.; Scholl, I.; Fuller, N.; Csillaghy, A.; Bentley, R. D.; Antonucci, E.; Ciminiera, L.; Finkelstein, A.; Ipson, S.; Messerotti, M.; Pike, D.; Vial, J. C.; Zharkova, V. Bibcode: 2006IAUS..233..229A Altcode: The European Grid of Solar Observations (EGSO) is a Solar virtual observatory (see Hill et al., 2002). It has been funded through the 5th Framework Program of the European Community. A dozen of laboratories, mixing Solar Physics and Information Technology, in Great Britain, France, Italy and Swiss have been involved in this project during 3 years. A grid accessing several dozens of databases and archives scattered all around the world has been developped as well as a Solar Event Catalogue and a Solar Feature Catalogue. The original aspect of this work consists in the possibility not only to search through the characteristics of observations, but also search for available data corresponding to specific kinds of events. So it is now very important to be able to follow the Sun 24 hours a day in order to enrich the events database for future queries. More informations on EGSO, catalogues and user interface can be accessd through the web site: http://www.egso.org/ Title: European Grid of Solar Observations (EGSO) Authors: Aboudarham, J.; Scholl, I.; Csillaghy, A.; Bentley, R. D.; Antonucci, E.; Ciminiera, L.; Finkelstein, A.; Ipson, S.; Messerotti, M.; Pike, D.; Vial, J. C.; Zharkova, V. Bibcode: 2006ihy..conf...18A Altcode: The EGSO project addresses the problem of combining heterogeneous data into a single "virtual" solar data resource. Wider access to other catalogues is enabled, including both pre-existing lists and new compilations generated using feature-recognition techniques on existing data. Scientists are also able to perform much richer data searches, based on solar events. Informations concerning EGSO can be found at http://www.egso.org/ Title: A brief introduction to SMESE mission Authors: Wang, C.; Fang, C.; Gan, W.; Prado, J. -Y.; Trottet, G.; Vial, J. -C.; Yan, Y.; Auchere, F.; Chang, J.; Molodi, G. Bibcode: 2006ilws.conf..211W Altcode: Small Exploration for Solar Eruptions (SMESE) is a joint mission between France and China to investigate the two main types of eruption events on the Sun: Coronal Mass Ejections (CME) and solar flares, and their relationship. SMESE will provide a set of unprecedented and complementary measurements including Ly-alpha imager, Ly-alpha coronagraph, EUV imager, Detection of Solar Infra red radiation, Hard X-ray/gamma ray spectrometry. SMESE aims to study, among others, the CME triggering mechanism and its acceleration in the corona, the particle acceleration by CME and solar flare, the physical association of the CME and solar flare etc. SMESE will be launched in the next solar maximum between 2010-2012. Title: Can we finally solve the problems of "Coronal Heating " and "Solar Wind Acceleration" in the Cosmic Vision era ? Authors: Maksimovic, M.; Appourchaux, T.; Aulanier, G.; Chust, T.; Dudok de Wit, T.; Klein, K. L.; Krasnoselskikh, V.; Louarn, P.; Roux, A.; Vial, J. C. Bibcode: 2006cosp...36.2999M Altcode: 2006cosp.meet.2999M Since the discovery of the corona s million-degree temperature in the 1940s and the supersonic solar wind in the early 1960s major efforts have been made to discover the physical mechanisms that could explain these two observations These efforts have led to a tremendous increase in our knowledge of our neighbour star the inner heliosphere and the Sun-Earth connections Unfortunately these efforts haven t allowed to provide a definitive answer to these questions Why such a situation On one hand the remote-sensing strategy has tried to probe the coronal properties by basically analysing the photons emitted or absorbed by the Sun s atmosphere With this regards limitations occur on both theoretical ground physics of the coupling between photons and plasma and experimental ground limited number of observables such as spectral lines or the hardly solvable problem of the line of sight integration On the other hand solar wind in-situ measurements have had access to the very detailed state of the local plasma properties full particles velocity distribution functions observations of the electromagnetic plasma fluctuations over a huge frequency range but at locations far from the corona and the solar wind acceleration regions Moreover it has been realized more recently that the magnetic field plays a fundamental role in shaping the low corona and channelling the energy inputs Unfortunately the measurement of the full magnetic vector in the corona is a very difficult enterprise and this lack of information hampers all on-going modelling efforts Given Title: SMESE, a SMall Explorer for the Study of solar Eruptions Authors: Vial, J. -C.; Auchère, F.; Chang, J.; Fang, C.; Gan, W. Q.; Molodij, G.; Prado, J. -Y.; Trottet, G.; Wang, C.; Yan, Y. H. Bibcode: 2006cosp...36.3287V Altcode: 2006cosp.meet.3287V The SMESE Small Explorer for the Study of solar Eruptions mission is a microsatellite proposed by France and China The payload of SMESE consists of three packages LYOT a suite of two UV and EUV imagers and a Lyman alpha coronagraph DESIR an Infra-Red Telescope working at 35 and 150 mu and HEBS a High Energy Burst Spectrometer working in X- and gamma -rays The status of research on Coronal Mass Ejections and flares will be briefly recalled in the context of on-going missions such as SOHO TRACE and RHESSI The scientific objectives and the profile of the mission will be described With a launch around 2011 SMESE will provide a unique tool for detecting and understanding eruptions flares and coronal mass ejections in the maximum phase of activity when the Solar Dynamics Observatory SDO should still be operating Title: SMESE: a Small Explorer for the Study of Solar Eruptions Authors: Vial, J. -C.; Auchère, F.; Chang, J.; Fang, C.; Gan, W. Q.; Molodij, G.; Prado, J. -Y.; Trottet, G.; Wang, C.; Yan, Y. H. Bibcode: 2006cosp...36.3294V Altcode: 2006cosp.meet.3294V The SMESE Small Explorer for the Study of solar Eruptions mission is a microsatellite proposed by France and China The payload of SMESE consists of three packages LYOT a suite of two UV and EUV imagers and a Lyman alpha coronagraph DESIR an Infra-Red Telescope working at 35 and 150 mu and HEBS a High Energy Burst Spectrometer working in X- and gamma -rays The status of research on Coronal Mass Ejections will be briefly recalled in the context of on-going missions such as SOHO TRACE and RHESSI The scientific objectives and the profile of the mission will be described With a launch around 2011 SMESE will provide a unique tool for detecting and understanding eruptions flares and coronal mass ejections in the maximum phase of activity and for the determination of the morphology of the low corona from where the solar wind originates Title: Multiwavelength Analysis of an Active Region Authors: Gontikakis, C.; Dara, H. C.; Zachariadis, Th. G.; Alissandrakis, C. E.; Nindos, A.; Vial, J. -C.; Tsiropoula, G. Bibcode: 2006SoPh..233...57G Altcode: We study active region NOAA 8541, observed with instruments on board SOHO, as well as with TRACE. The data set mainly covers the transition region and the low corona. In selected loops studied with SUMER on SOHO, the VIII 770 Å line is systematically redshifted. In order to estimate the plasma velocity, we combine the Doppler shifts with proper motions (TRACE) along these loops. In the case of an ejection, apparently caused by the emergence of a parasitic polarity, proper motions and Doppler shifts give consistent results for the velocity. A cooler loop, observed in the same active region with CDS, shows a unidirectional motion reminiscent of a siphon flow. The derived electron temperature and density along a large steady loop confirm that it cannot be described by hydrostatic models. Title: Solar Hydrogen Lyman Contimuum Observations with Soho/sumer Authors: Parenti, S.; Vial, J. -C.; Lemaire, P. Bibcode: 2005ESASP.600E..93P Altcode: 2005ESPM...11...93P; 2005dysu.confE..93P No abstract at ADS 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. Bibcode: 2005ESASP.588..389A Altcode: 2005tssc.conf..389A No abstract at ADS Title: Hydrogen Lyman α Profiles of AN Active Region Filament Obtained with SUMER on SOHO Authors: Vial, J. -C.; Boutry, C.; Wilhelm, K. Bibcode: 2005ESASP.600E.102V Altcode: 2005ESPM...11..102V; 2005dysu.confE.102V No abstract at ADS Title: Prominence atlas in the SUMER range 800-1250 Å. II. Line profile properties and ions identifications Authors: Parenti, S.; Vial, J. -C.; Lemaire, P. Bibcode: 2005A&A...443..679P Altcode: We present a SOHO/SUMER spectral atlas in the 800-1250 Å range of a prominence and a Quiet Sun (QS) region observed in 1999. The atlas is produced for two separate areas of the prominence. The QS spectrum is used as a reference. This is the first prominence atlas obtained with high spectral resolution (≈0.044 Å). It provides information concerning more than 550 line profiles, in terms of position, total radiance, and FWHM, along with the ion identification. Forty new lines have been identified with respect to previously published spectra. Title: A new relation between the central spectral solar H I Lyman α irradiance and the line irradiance measured by SUMER/SOHO during the cycle 23 Authors: Emerich, Claude; Lemaire, Philippe; Vial, Jean-Claude; Curdt, Werner; Schühle, Udo; Wilhelm, Klaus Bibcode: 2005Icar..178..429E Altcode: The spectral irradiance at the center of the solar H I Lyman α ( λ=121.5664nm, referred to as Lyα in this paper) line profile is the main excitation source responsible for the atomic hydrogen resonant scattering of cool material in our Solar System. It has therefore to be known with the best possible accuracy in order to model the various Lyα emissions taking place in planetary, cometary, and interplanetary environments. Since the only permanently monitored solar irradiance is the total one (i.e. integrated over the whole Lyα line profile), Vidal-Madjar [1975. Evolution of the solar Lyman alpha flux during four consecutive years. Solar Phys. 40, 69-86] using Orbiting Solar Observatory 5 (OSO-5) satellite Lyα data, established a semi-empirical formula allowing him to deduce the central spectral Lyα irradiance from the total one. This relation has been extensively used for three decades. But, at the low altitude of the OSO-5 orbit, the central part of the solar line profile was deeply absorbed by a large column of exospheric atomic hydrogen. Consequently, the spectral irradiance at the center of the line was obtained by a complex procedure confronting the observations with simulations of both the geocoronal absorption and the self-reversed shape of the solar Lyα profile. The SUMER spectrometer onboard SOHO positioned well outside the hydrogen geocorona, provided full-Sun Lyα profiles, not affected by such an absorption [Lemaire et al., 1998. Solar H I Lyman α full disk profile obtained with the SUMER/SOHO spectrometer. Astron. Astrophys. 334, 1095-1098; 2002. Variation of the full Sun Hydrogen Lyman α and β profiles with the activity cycle. Proc. SOHO 11 Symposium, ESA SP-508, 219-222; 2004. Variation of the full Sun Hydrogen Lyman profiles through solar cycle 23. COSPAR 2004 Meeting], making it—for the first time—possible to measure the spectral and total Lyα solar irradiances directly and simultaneously. A new relation between these two quantities is derived in an expression that is formally similar to the previous one, but with significantly different parameters. After having discussed the potential causes for such differences, it is suggested that the new relation should replace the old one for any future modeling of the numerous Lyα absorptions and emissions observed in the Solar System. Title: Solar hydrogen-Lyman continuum observations with SOHO/SUMER Authors: Parenti, S.; Lemaire, P.; Vial, J. -C. Bibcode: 2005A&A...443..685P Altcode: In this work we analyze the emission of the H Lyman continuum (HI LyC) in the Quiet Sun (QS) and a solar prominence, in order to derive information on the temperature of the emitting plasma. We used the spectral atlas obtained with SOHO/SUMER detector A in 1999 (Parenti et al. 2005, A&A, 443, 679). The high spectral resolution of this instrument allows a good selection of the continuum, free from emission lines. However, in the HI LyC wavelength domain, the data suffer from large radiometric uncertainties, which lead us to use detector B as a reference. We obtained electron temperatures of 8281 K ± 280 K and 7564 K ± 230 K in two separate parts of the prominence. Title: Radiative Signatures of Coronal Loops Submitted to Turbulent Heating Authors: Parenti, S.; Buchlin, E.; Galtier, S.; Vial, J. -C. Bibcode: 2005ESASP.592..523P Altcode: 2005soho...16E..97P; 2005ESASP.592E..97P No abstract at ADS Title: Formation flyers applied to solar coronal observations: the ASPICS mission Authors: Vives, S.; Lamy, P.; Auchere, F.; Vial, J. -C.; Koutchmy, S.; Arnaud, J.; Prado, J. -Y.; Frassetto, F.; Naletto, G. Bibcode: 2005SPIE.5901..305V Altcode: Classical externally-occulted coronagraphs are presently limited in their performances by the distance between the external occulter and the front objective. The diffraction fringe from the occulter and the vignetted pupil which degrades the spatial resolution prevent observing the inner corona inside typically 2-2.5 solar radii. Formation flyers open new perspectives and allow to conceive giant, externally-occulted coronagraphs using a two-component space system with the external occulter on one spacecraft and the optical instrument on the other spacecraft at approximately 100 m from the first one. ASPICS (Association de Satellites Pour l'Imagerie Coronographique Solaire) is a mission proposed to CNES in the framework of their demonstration program of formation flyers which is presently under study to exploit this technique for coronal observations. In the baseline concept, ASPICS includes three coronagraphs operating in three spectral domains: the visible continuum (K-corona brightness), the HI Lyman alpha emission line at 121.6 nm, and the HeII emission line at 30.4 nm. Their unvignetted fields of view extend from 1.1 to 3.2 solar radii with a typical spatial resolution of 3 arcsec. In order to connect coronal activity to photospheric events, ASPICS further includes two disk imagers. The first one is devoted to the HI Lyman alpha emission line. The second one is a multi-channel instrument similar to SOHO/EIT and devoted to the HeII (30.4 nm), FeIX/X (17.1 nm) and FeXII (19.5 nm) emission lines. Two concepts of the space system are under consideration: a symmetric configuration where the disk imagers and the external occulter are on one spacecraft and the coronagraphs on the other, an asymmetric configuration where the external occulter is on one spacecraft and the scientific instruments are regrouped on the other one. Title: EGSO - A maturing VO for Solar Physics Authors: Bentley, R. D.; Scholl, I.; Csillaghy, A.; Aboudarham, J.; Antonucci, E.; Gurman, J.; Hill, F.; Pike, D.; Vial, J.; Zharkova, V. Bibcode: 2005AGUSMSH43B..01B Altcode: The European Grid of Solar Observations, EGSO, is a Grid test-bed funded under the Information Societies Thematic Priority of the European Commission's Fifth Framework Programme (FP5). In the case of EGSO, the application chosen was the use of Grid technology to establish a virtual observatory for solar physics, and the project addresses the generic problem of how to provide access to a distributed, heterogeneous data set for a scattered user community. In order to identify observations that match a user's search criteria, EGSO has been building an environment that will support complex searches. Because of the absence of the metadata needed to tie the heterogeneous data together, EGSO has placed emphasis on the provision of databases that can be accessed from the Internet through special providers. The provision of appropriate metadata is of extreme importance in establishing a virtual observatory, and the approach used can be adapted to facilitate the inclusion of any data, including non-solar data. We report on the capabilities of EGSO and discuss experience gained in creating the facility. We also discuss how EGSO has been working with other virtual observatories that support the solar, heliospheric and space plasma communities in order to try to achieve interoperability between the numerous data sets. We highlight what we consider are the most profitable ways of doing this. Title: EUV imaging spectrometer for the Solar Orbiter mission Authors: Millard, A. A.; Lemaire, P.; Vial, J. -C. Bibcode: 2005AdSpR..36.1411M Altcode: The results from missions such as Yohkoh, Trace or SOHO have advanced our understanding of the solar corona and heliosphere, but also have raised many new questions. Measurements at higher spatial resolution and cadence are needed, some regions such as the solar poles or the inner heliosphere remain unexplored. The Solar Orbiter mission addresses those questions. UV imaging spectrometers may be included in the remote sensing instruments package for this mission. Fourier transform spectrometry (FTS) is an ideal solution for imaging systems as there is no need to scan the region of interest with a slit to get a 2D map, and the spectral range covered is only limited by the bandpass of the filter and the maximum optical path difference that can be obtained. FTS systems also allow to make observations at high cadence (100 Hz). Working in the far UV (below 200 nm) requires the use of reflective only optical systems. A solution for such an instrument has been designed at IAS and a mock-up has been built in order to test and validate the working principle. The first results of the alignment phase are shown. Title: Variation of the full Sun hydrogen Lyman profiles through solar cycle 23 Authors: Lemaire, P.; Emerich, C.; Vial, J. -C.; Curdt, W.; Schühle, U.; Wilhelm, K. Bibcode: 2005AdSpR..35..384L Altcode: The hydrogen Lyman (Lyα, 121.267 nm and Lyβ, 102.572 nm) lines are important contributors to the solar extreme ultra violet (EUV) flux which illuminates the upper Earth’s atmosphere. From high resolution spectral observations performed with the solar ultraviolet measurement of emitted radiations (SUMER) spectrometer on the Solar and Heliospheric Observatory (SOHO), the detailed profiles of these two lines have been obtained. Some insights into the variation of the shape of the profiles, sampled throughout the present solar cycle 23, are given and discussed. Title: Solar Orbiter: A unique opportunity for investigating small-scale physical processes at work in the magnetic solar atmosphere Authors: Vial, J. -C. Bibcode: 2005AdSpR..36.1375V Altcode: With knowledge gained from the recent ULYSSES, SOHO, TRACE and other missions, a great deal of progress has been made in our understanding of the structure and dynamics of the various regions of the solar atmosphere: e.g., transition region and "quiet" corona, coronal holes and active region loops. However, no clear conclusions can yet be drawn about the fundamental processes that determine the existence and the underlying physics of these regions, especially their observed high temperature and flows. The lack of adequate spatial resolution has limited the study of the continuum between cool/hot, source/sink, and magnetic/non-magnetic regions. We consider here, magnetic reconnection as an example of the basic processes that are most likely involved at many different scales in heating and particle acceleration. Starting with a possible mechanism for reconnection (flux emergence), we consider different remote-sensing signatures of reconnection: flows, field rearrangement, impulsive heating, particle acceleration, wave generation, propagation and dissipation. We discuss their small-scale properties derived from current measurements and ways to improve their observation. We also consider how remote sensing and in situ measurements could be coordinated. To demonstrate how these advances might be achieved, we discuss the potential for discoveries offered by the Solar Orbiter, resulting notably from its relatively high spatial resolution and its capacity to observe for a substantial time in co-rotation with the Sun. Title: Coronal Magnetometry Authors: Arnaud, J.; Faurobert, M.; Grec, G.; Vial, J. -C. Bibcode: 2005EAS....14...95A Altcode: Magnetic fields emerging in the solar atmosphere control the structure, dynamics and heating of the solar corona. Those fields remain essentially unattainable with present low corona instrumentation. We present the most direct way of magnetic field remote measurements in the internal corona, namely visible and infrared coronal emission lines magnetometry and we explain why Dome C should be investigated as a likely outstanding site for such observations. We develop a strategy towards a large aperture coronal magnetometer at Dome C in the context of the other main instrumental projects underway for solar physics. Title: Modelling the Radiative Signatures of Turbulent Heating in Coronal Loops Authors: Parenti, S.; Buchlin, E.; Galtier, S.; Vial, J. -C. Bibcode: 2004ESASP.575..497P Altcode: 2004soho...15..497P No abstract at ADS Title: Solving Science Use Cases that relate to the Sun and Heliosphere with EGSO Authors: Bentley, R. D.; Scholl, I.; Csillaghy, A.; Aboudarham, J.; Antonucci, E.; Gurman, J. B.; Hill, F.; Pike, D.; Vial, J.; Zharkova, V. Bibcode: 2004AGUFMSH21B0415B Altcode: The European Grid of Solar Observations (EGSO) is a grid testbed funded by the European Commission's Fifth Framework Programme under its Information Society Technologies (IST) thematic priority. The project started in 2002 and is designed to provide enhanced access to solar and related data around the world. The EGSO grid is composed of two main components, Roles to set up the grid and, catalogs and registries to allow roles to answer users queries. Catalogs are made of lists of observations, events and features (a new service provided by EGSO). Registries are built from these catalogs and organized in order to enhance search capabilities. EGSO is working closely with other virtual observatory (VO) projects in the solar physics and related domains. This includes the US Virtual Solar Observatory (VSO) and the Collaborative Sun-Earth Connector (CoSEC). More recently we have been working with the Virtual Space Plasma Observatory (VSPO) and have contact with the Virtual Heliospheric Observatory (VHO). Through discussions with future missions, and within the new IAU Working Group on ``International Data Access'' (Solar and Heliospheric), the VOs are studying ways of ensuring interoperability from the ``sun to dirt''. This type of integrated access will be particularly important to missions such as STEREO and Living Witha Star. In this paper we will report the current status of EGSO, demonstrate how the catalogs and registries model serves within the user interface, and show how the user can retrieve solar and heliospheric data to match a scientific query. EGSO Release 4 is now being Beta-tested by users and anyone interested should view the Web page detailing all the EGSO capabilities under http://www.egso.org/demo Title: Simplified simulations of MHD Authors: Buchlin, É.; Velli, Marco; Galtier, Sébastien; Vial, Jean-Claude Bibcode: 2004sf2a.conf...91B Altcode: 2004sf2a.confE.334B Because of the wide range of scales involved in MHD turbulence, a statistical approach may become necessary to keep a global view of this complex phenomenon. In particular, in the framework of the heating of the solar corona, the smallest events are not directly detectable by the current instruments but may be integrated to a statistical study. From the numerical point of view, the contradictory needs for computing speed and good description of MHD solutions may be addressed by simplified models, which keep the most possible of the complex and non-linear physics of the MHD equations but run sufficiently fast to produce statistics of fields, of structures, and of "events". We propose two such models which have been originally developed to represent coronal loops (with forcing and Alfvén wave reflection at the loop's foot-points), but which may be adapted to represent any region with a dominant large-scale magnetic field. The first model consists of a set of cellular automata, in which the non-linear terms of the MHD equations are modelled by a threshold dynamics on current density (Buchlin et al. A&A, 2003). In the second model, the cellular automata are replaced by shell-models of MHD, so as to reach a greater range of wavenumbers and to model more realistically the non-linear couplings between modes at different scales. The results obtained with these models will be presented and consequences of this study for observational statistics and for theory of MHD turbulence will be discussed. Title: Imagerie et spectrométrie dans l'UV pour les missions spatiales solaires LYOT et Solar Orbiter Authors: Millard, A.; Lemaire, P.; Vial, J. -C. Bibcode: 2004JPhy4.119..235M Altcode: A l'horizon 2010, les missions spatiales solaires LYOT et Solar Orbiter permettront d'effectuer des observations du soleil (disque et couronne) dans l'UV à des résolutions spatiale et temporelle jamais réalisées auparavant. Pour atteindre ce but, les deux missions utiliseront en particulier des spectro-imageurs. La longueur d'onde de travail impose un schéma optique original uniquement en réflexion et utilisant des réseaux de diffraction. Le concept d'un tel instrument est décrit ici, et l'avancement de la maquette réalisée à l'IAS sont présentés. Title: Prominence corona transition region plasma diagnostics from SOHO observations Authors: Cirigliano, D.; Vial, J. -C.; Rovira, M. Bibcode: 2004SoPh..223...95C Altcode: New results concerning prominence observations and in particular the prominence-corona transition region (PCTR) are presented. In order to cover a temperature range from 2 × 104 to 7 × 105 K, several emission lines in many different ionization states were observed with SUMER and CDS on board SOHO. EM and DEM were measured through the whole PCTR. We compared the prominence DEM with the DEM from other solar structures (active region, coronal hole and the chromosphere-corona transition region (CCTR)). We notice a displacement of the prominence DEM minimum towards lower temperatures with respect to the minimum of the other structures. Electron density and pressure diagnostics have been made from the observed C III lines. Local electron density and pressure for T ∼ 7 × 104 K are respectively log Ne = 9.30−0.34+0.30 and 0.0405−0.014+0.012. Extrapolations over the entire PCTR temperature range are in good agreement with previous SOHO results (Madjarska et al., 1999). We also provide values of electron density and pressure in two different regions of the prominence (center and edge). The Doppler velocity in the PCTR shows a trend to increase with temperature (at least up to 30 km s -1 at T ∼ 7 × 104 K), an indication of important mass flows. A simple morphological model is proposed from density and motion diagnostics. If the prominence is taken as a magnetic flux tube, one can derive an opening of the field lines with increasing temperature. If the prominence is represented as a collection of threads, their number increases with temperature from 20 to 800. Derived filling factors can reach values as low as 10−3 for a layer thickness of the order of 5000 km. The variation of non-thermal velocities is determined for the first time, in the temperature range from 2 × 104 to 7 × 105 K. The quite clear similarity with the CCTR non-thermal velocities would indicate that heating mechanisms in the PCTR could be the same as in the CCTR (wave propagation, turbulence MHD). Title: EUV imager and spectrometer for Lyot and Solar Orbiter space missions Authors: Millard, Anne; Lemaire, Philippe; Vial, Jean-Claude Bibcode: 2004ESASP.554..351M Altcode: 2004icso.conf..351M In the 2010 horizon, solar space missions such as LYOT and Solar Orbiter will allow high cadence UV observations of the Sun at spatial and spectral resolution never obtained before. To reach these goals, the two missions could take advantage of spectro-imagers. A reflective only optical solution for such an instrument is described in this paper and the first results of the mock-up being built at IAS are shown. Title: A New Relation between Central and Total Solar H I Lyman-α Irradiances, as measured by SOHO during Solar Cycle 23 (1996-2003) Authors: Emerich, C.; Lemaire, P.; Vial, J. -C.; Curdt, W.; Schüle, U.; Wilhelm, K. Bibcode: 2004AAS...204.9802E Altcode: 2004BAAS...36..984E The spectral irradiance at the center of the solar H Ly-α line profile is the main excitation source responsible for the atomic hydrogen resonant scattering in cool material. It has therefore to be known with the best possible accuracy to model the H Ly-α emissions taking place in planetary, cometary and interplanetary environments. On the other hand, the only permanently monitored solar irradiance is the total one - either measured by near-Earth satellites, or deduced from its correlation with solar activity indexes. It is the reason why Vidal-Madjar (1975) using OSO-5 satellite H Ly-α data, established a semi-empirical formula allowing to deduce the central H Ly-α irradiance from the integrated one. This relation has been extensively used for three decades. In fact, at the low altitude of the OSO-5 orbit, the observed central part of the solar line profiles was deeply absorbed by a large column of exospheric atomic hydrogen. Consequently, the solar line center irradiances were not measured directly, but obtained by confronting the measurements with simulations of both the geocoronal absorption and the self-reversed shape of the central solar profile itself.

On the contrary, the SOHO/SUMER spectrometer orbiting well outside the H geocoronal envelope (at the L1 Sun-Earth Lagrange point), provided full Sun H Ly-α profiles, exempt from any central geocoronal absorption (Lemaire et al. (1998, 2002, 2004)). This has made it possible to directly measure the central H Ly-α solar irradiances as a function of the integrated ones, during eight years of Solar Cycle 23. The newly obtained relation confirms the general trend of the previous one, but it is characterized by significantly different coefficients. It will therefore provide new and more accurate inputs for the future modeling of the various Ly-α emissions occurring inside the Solar System. Title: Flare observation of the Sun as a star by SUMER/SOHO in the hydrogen Lyman continuum Authors: Lemaire, P.; Gouttebroze, P.; Vial, J. -C.; Curdt, W.; Schühle, U.; Wilhelm, K. Bibcode: 2004A&A...418..737L Altcode: During the execution of the programme ``Sun as a star'', while the SUMER (Solar Ultraviolet Emission of Emitted Radiation)/SOHO (SOlar and Heliospheric Observatory) slit was collecting the scattered radiation from the telescope mirror far away from the solar disk image, a class X5.3/3b flare erupted on the solar disk, on 25 August 2001. During the first phase of the flare a relative increase of a few percent was detected at the head of the hydrogen Lyman continuum. After correction from the instrumental parameters, the relative signal increase is 70% at the head of the Lyman continuum (910 Å), and 190% in the C II 904 Å multiplet. Accounting for the area of the flare region, the local increase of the radiance of the Lyman continuum and of the C II lines is estimated to be a factor of several thousands. We compare this result with other solar observations and models.

Appendix A is only available in electronic form at http://www.edpsciences.org Title: Prominence atlas in the SUMER range 800 1250 Å: I. Observations, data reduction and preliminary results Authors: Parenti, S.; Vial, J. -C.; Lemaire, P. Bibcode: 2004SoPh..220...61P Altcode: The aim of this work is to build an EUV-UV spectral catalogue of a prominence. Here we focus on the preparatory work for the final result and we give an example of the results obtained. As a first step, we present the information needed for a full understanding of the results that will form the final entire catalogue. The data are composed of a full SUMER spectrum in the range 800-1250 Å of a prominence observed on 8 October 1999. A quiet-Sun area was also observed in the same spectral range in order to have a reference spectrum. Beside the standard corrections, we give details of the estimated stray light and the wavelength calibration of both datasets. We also present a short list of lines as an example of the results from the line-fitting procedure we applied to the data. For each line we give the measured position, the total intensity and the FWHM in the quiet Sun and at two different spatial positions in the prominence. With a final atlas of the prominence it will be possible to investigate several properties of the feature such as mass motion, differential emission measure, density, and elemental composition. Title: Optical design of the Lyman alpha coronagraph for the LYOT microsatellite Authors: Vives, Sebastien; Lamy, Philippe L.; Vial, Jean-Claude Bibcode: 2004SPIE.5171..298V Altcode: The LYOT (LYman Orbiting Telescope) solar mission (proposed for a CNES micro-satellite) is composed of a disk imager and a coronagraph, both working at Lyman-α (121.6 nm). The coronagraph is internally occulted and all-reflective with a field-of-view of 1.2 R up to 2.5 R and high spatial resolution (2 pixels) amounts to 5 arcsec. The optical design is driven by the requirement to use a superpolished spherical mirror to minimize the scattered light into the instrument. The LYOT mission will observe the Lyman-α corona at high cadence (1 image/5 minutes) over a period of two years. Title: Variation of the full Sun hydrogen Lyman profiles through solar cycle 23 Authors: Lemaire, P.; Emerich, C.; Vial, J. -C.; Curdt, W.; Schühle, U.; Wilhelm, K. Bibcode: 2004cosp...35..510L Altcode: 2004cosp.meet..510L The hydrogen Lyman (121.267 nm and 102.572 nm) lines are important contributors to the solar EUV flux which illuminates the upper Earth's atmosphere. From high resolution spectral observations performed with the SUMER FUV-EUV spectrometer on SoHO, the detailed profiles of these two lines have been obtained. Some insights into the variation of the shape of the profiles, sampled throughout the present solar cycle 23, are shown and discussed. Title: UV imager and spectrometer for LYOT and Solar Orbiter space missions Authors: Millard, A.; Lemaire, P.; Vial, J. -C. Bibcode: 2004cosp...35.1749M Altcode: 2004cosp.meet.1749M The results from missions such as Yohkoh, Trace or SOHO have advanced our understanding of the solar corona and heliosphere, but also have raised many new questions. Measurements at higher spatial resolution and cadence are needed, some regions such as the solar poles or the inner heliosphere remain unexplored. Both LYOT and Solar Orbiter mission address those questions. UV imaging spectrometers may be included in the remote sensing instruments packages for these missions. Fourier transform spectrometry (FTS) is an ideal solution for imaging systems as there is no need to scan the region of interest with a slit to get a 2D map, and the spectral ranged covered is only limited by the bandpass of the filter and the maximum optical path difference that can be obtained. FTS systems also allows to make observations at high cadence (100 Hz). Working in the far UV (below 200 nm) requires the use of reflective only optical systems. A solution for such an instrument has been designed at IAS and a mock-up has been built in order to test and validate the working principle. The first results of the alignment phase are shown. Title: Statistical Study of SOHO/SUMER Full-Sun Images Authors: Buchlin, E.; Vial, J. -C.; Lemaire, P.; Galtier, S. Bibcode: 2004ESASP.547..337B Altcode: 2004soho...13..337B A series of full-Sun observations was performed with the SoHO/SUMER instrument between March and October 1996. Some moments of the S VI 93.3nm, S VI 94.4nm, and Ly line profiles were computed on-board. Intensities and line-of-sight velocities in a large central region of the Sun are studied statistically: histograms of intensities are computed, as well as histograms of total intensities of "events", and structure functions of the intensity field. Some statistics of velocities are the first to be obtained from observational data. The aim is to compare these statistics to results previously obtained with SoHO/EIT and by numerical simulations of MHD. Signatures of turbulent intermittency are also researched. Title: Statistical properties of turbulence and intermittency in the solar corona observed in EUV Authors: Buchlin, E.; Vial, J. -C.; Lemaire, P. Bibcode: 2004cosp...35.3556B Altcode: 2004cosp.meet.3556B Statistical properties of the fields observed on the Sun in EUV may help to understand turbulence in the solar corona and give clues to the processes involved in the heating of the corona to millions of degrees. In this study, we use a series of full-Sun images obtained in 1996 by the SUMER spectroheliograph on SoHO. Each observation consists of eight limb-to-limb raster scans in the lines Ly ɛ, S VI 193.3 nm, and S VI 194.4 nm. Intensities, Doppler velocity shifts and line widths were computed on-board. A context spectrum was measured for each observation. Intensities and line-of-sight velocities data in a large central region of the Sun are then studied statistically: histograms of data values and of events, structure functions, and other statistics are computed. They are compared to results obtained by imaging instruments like SoHO/EIT and to numerical simulations of MHD. Structure functions of the velocity field reveal that turbulence in the corona may be intermittent. Title: Integrated Access to Solar Data using EGSO Authors: Bentley, R. D.; Csillaghy, A.; Scholl, I.; Vial, J. -C.; Aboudarham, J.; Antonucci, E.; Zharkova, V. V.; Pike, C. D. Bibcode: 2004cosp...35.3935B Altcode: 2004cosp.meet.3935B The European Grid of Solar Observations (EGSO) is a virtual observatory based on Grid technology that will change the way users analyze solar data. EGSO is funded under the IST (Information Society Technologies) thematic priority of the European Commission's Fifth Framework Programme (FP5). It started in March 2002 and will last for 3 years. The EGSO Consortium comprises eleven groups from five countries in Europe and the US, and is led by the Mullard Space Science Laboratory of University College London. The project aims to overcome one of the major hurdles in the analysis of solar data - finding what data are available and retrieving those that are needed. EGSO is creating layers of metadata catalogues that will for the first time provide the ability to select solar data based on phenomena and events. It is also integrating access to solar data by building a Grid including solar archives around the world. This combination of metadata and tools for selecting, processing and retrieving distributed and heterogeneous solar data, will radically change the way that data are distributed and analyzed. EGSO is collaborating closely with groups in the US who are working on similar virtual observatory projects for the solar, solar-terrestrial and heliospheric communities with the objective of providing integrated access to these data. In particular, strong synergies between the EGSO and CoSEC projects are producing innovative ways of accessing the data that will be deployed in both projects. Since the first release of EGSO in September 2003, members of the solar community have been involved in product testing. The constant testing and feedback allows us to continue to improve the quality and usability of the system. The capabilities of the latest release (R4) will be described, and the scientific problems that it addresses discussed. Title: SOLAR ORBITER : a unique opportunity for investigating the physical processes at work in the magnetic solar atmosphere Authors: Vial, J. -C. Bibcode: 2004cosp...35.3808V Altcode: 2004cosp.meet.3808V With recent ULYSSES, SOHO, TRACE (and other) missions, much progress has been made on the issues of structuring and dynamics in various regions of the solar atmosphere : transition region and ``quiet'' corona, coronal holes, active region loops. However, no clear conclusion could be drawn about the processes which determine their existence and their physics, especially their observed high temperatures or flows. For one reason, the lack of sufficient spatial resolution at all observed wavelengths has prevented to study the continuity between cool/hot, source/deposit, magnetic/non magnetic regions. For another reason, the study of the important regions of open magnetic field (mostly located at poles) has faced the severe drawback of observations performed from the ecliptic plane, except for (in-situ) ULYSSES measurements at a few A.U. We discuss the potential of discoveries offered by Solar Orbiter resulting notably from its spatial resolution performances and its capacity to fly above the ecliptic plane. We also stress how it is essential that remote sensing and in-situ measurements be coordinated. Title: A search for turbulent wave heating and acceleration signatures with SOHO/SUMER observations : Measurements of the widths of off-limb Iron lines Authors: Dolla, L.; Lemaire, P.; Solomon, J.; Vial, J. -C. Bibcode: 2003AIPC..679..351D Altcode: The widths of coronal ions lines may contain important information about the energetics of the solar wind and corona. We present a method to measure these widths, taking into account the problems of instrumental stray light inherent to SoHO/SUMER. The Iron lines are interesting to set an upper limit on the ``unresolved'' velocity, that may be a signature of turbulent or wave motion in the corona. Title: A solar cellular automata model issued from reduced MHD Authors: Buchlin, E.; Aletti, V.; Galtier, S.; Velli, M.; Vial, J. -C. Bibcode: 2003AIPC..679..335B Altcode: A three-dimensional cellular automata (CA) model inspired by the reduced magnetohydrodynamic equations is presented to describe impulsive events generated along a coronal magnetic loop. It consists of a set of planes, distributed along the loop, between which the information propagates through Alfvén waves. Statistical properties in terms of power laws are obtained in agreement with SoHO observations of X-ray bright points of the quiet Sun. Physical meaning and limits of the model are discussed. Title: A simplified numerical model of coronal energy dissipation based on reduced MHD Authors: Buchlin, E.; Aletti, V.; Galtier, S.; Velli, M.; Einaudi, G.; Vial, J. -C. Bibcode: 2003A&A...406.1061B Altcode: 2002astro.ph.12444B A 3D model intermediate between cellular automata (CA) models and the reduced magnetohydrodynamic (RMHD) equations is presented to simulate solar impulsive events generated along a coronal magnetic loop. The model consists of a set of planes distributed along a magnetic loop between which the information propagates through Alfvén waves. Statistical properties in terms of power-laws for energies and durations of dissipative events are obtained, {and their} agreement with X-ray and UV flares observations {is discussed}. The existence of observational biases is {also} discussed. Title: Distributions of Coronal Events: Simulations and Event Definitions Authors: Buchlin, Éric; Galtier, Sébastien; Velli, Marco; Vial, Jean-Claude Bibcode: 2003ANS...324..109B Altcode: 2003ANS...324..P15B No abstract at ADS 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 Bibcode: 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 Ro 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: Modelo semi-empírico de protuberancia solar a partir del diagnóstico de densidades Authors: Cirigliano, D.; Vial, J. C.; Rovira, M. Bibcode: 2003BAAA...46....7C Altcode: A partir de la observación del espectro del quintuplete de C III alrededor de 1175 Å, se ha realizado el diagnóstico de la densidad y presión electrónica, basado en el cálculo del cociente de las intensidades observadas. Una vez establecida la densidad electrónica, y con el cálculo de las velocidades Doppler, hemos investigado el flujo de masa en la protuberancia en función de la temperatura. Estableciendo como hipótesis la conservación del número de partículas que ingresan y salen del cuerpo de la protuberancia, se investiga la variación del área de un tubo de flujo semi-empírico en función de la temperatura. A partir de dicho diagnóstico, se examina el comportamiento del radio del tubo magnético en función de la temperatura, los que dan cuenta de la abertura de las líneas de campo magnético que confinan el plasma y de la divergencia del campo magnético en diferentes alturas de la atmósfera solar. Title: Some advances in the thermodynamic diagnostic of solar prominences Authors: Vial, J. -C. Bibcode: 2003EAS.....9..133V Altcode: The aim of this paper is to present some recent advances in the diagnostic of solar prominences, with an emphasis put on the results obtained with SOHO through its six years of observations. We show the progress made since the Hvar Reference Model in the determination of basic thermodynamic parameters, especially in the Prominence-Corona Transtion Region (PCTR). We address the important contribution of ``prominence seismology" for determining e.g. density and magnetic field. We summarize the most recent comparisons between non-LTE modelling predictions and spectra of optically thick lines. Finally, we mention the most recent magnetic measurements which seem to challenge the historic Hanle measurements of Leroy ([CITE]) as summarized in Bommier et al. ([CITE]). Title: Line profiles and intensity ratios in prominence models with a prominence to corona interface Authors: Labrosse, N.; Gouttebroze, P.; Heinzel, P.; Vial, J. -C. Bibcode: 2002ESASP.506..451L Altcode: 2002svco.conf..451L; 2002ESPM...10..451L In this work we study the hydrogen, helium and calcium spectra emitted by a one-dimensional prominence model in magneto-hydrostatic equilibrium. The prominence slab consists of two parts: a cool core where the plasma is optically thick for some lines, and a prominence-to-corona transition region (PCTR) with a strong temperature gradient. The models are defined by 5 parameters: temperature, pressure, slab thickness, microturbulent velocity and altitude. We solve the NLTE radiative transfer equations for all optically thick transitions. We present line ratios between infrared, optical and EUV lines, as well as line profiles. We show that the presence of a PCTR, where both collisional and radiative excitations are important, affects H, He, and Ca populations and emergent lines in different manners. Title: Quiet-Sun chromospheric network evolution Authors: Lemaire, Philippe; Vial, J. -C.; Curdt, W.; Schühle, U.; Wilhelm, K. Bibcode: 2002ESASP.505..477L Altcode: 2002solm.conf..477L; 2002IAUCo.188..477L Using the SUMER/SOHO spectrometer we have observed the same quiet-Sun area during several days in a set of eight spectral lines of the transition region. Line intensity maps of the rastered areas are used to separate the interior of the supergranular cells from the network. Then, following the evolution of the supergranular pattern, we measure the variations of intensity and the Doppler shifts at several temperatures of formation of the transition region. We find that the overall flow velocity of the cell interior and the network generally decays within ten hours, which represents a significant part of the supergranular lifetime. Title: Study of coronal loops using TRACE and SOHO Authors: Gontikakis, C.; Dara, H. C.; Zachariadis, Th.; Nindos, A.; Alissandrakis, C.; Tsiropoula, G.; Vial, J. -C. Bibcode: 2002ESASP.505..417G Altcode: 2002solm.conf..417G; 2002IAUCo.188..417G We analysed coronal loops observed in many spectral lines from TRACE and SUMER, at the active region NOAA 8541, on May 15, 1999. For the loops, which are identified in a number of wavelengths, we try to combine the good temporal and spatial resolution of TRACE with the spectral information obtained by the SUMER rasters, in order to determine some physical parameters such as temperature, flow velocity and electron density. The morphology of the magnetic field of the loops is also approximated by a force-free extrapolation of the photospheric magnetic field, measured with MDI, and is compared to the loop morphology. Title: Prediction of line intensity ratios in solar prominences Authors: Gouttebroze, P.; Labrosse, N.; Heinzel, P.; Vial, J. -C. Bibcode: 2002ESASP.505..421G Altcode: 2002solm.conf..421G; 2002IAUCo.188..421G Solar prominences are made of relatively cool and dense plasma embedded in the solar corona, supported and structured by the magnetic field. Since this plasma is definitely out of LTE, the diagnosis of physical conditions in prominences needs the use of specific radiative transfer (RT) codes to predict the spectrum emitted by models and compare it to observations. For optically thin lines, the solution of RT equations in the transition itself is not required, but the emitted intensities depend, via the statistical equilibrium equations, on RT in other transitions which are optically thick. We use two different sets of models. The first one contains monolithic models defined by 5 parameters: temperature, pressure, thickness, microturbulent velocity and altitude above the solar surface. For each parameter, we assume a range of variation. For each model, the values of the 5 parameters are randomly chosen within the corresponding range of variation. The second set contains composite models made of multiple layers, in order to simulate the penetration of radiation into inhomogeneous prominences. We use NLTE radiative transfer codes to compute the intensities of the lines of hydrogen, helium and calcium emitted by each model. So, for any couple of lines, we may obtained their intensity ratio as a function of the 5 parameters. We discuss the behaviour of some of these intensity ratios as a function of the principal parameters and construct distribution diagrams, which are compared to different published observations. Title: MHD waves in active region filament from SOHO-THEMIS joint observations Authors: Régnier, S.; Solomon, J.; Vial, J. C.; Mein, P. Bibcode: 2002ESASP.505..647R Altcode: 2002IAUCo.188..647R; 2002solm.conf..647R The stability of solar filaments and their implications for eruptive events can be revealed by the existence of magnetohydrodynamic (MHD) waves. During the MEDOC campaign on May 2000, we performed joint observations involving SOHO and THEMIS instruments (CDS and MSDP respectively). We analyse the modes of oscillations for several spectral lines (Hα at 6563 Å, He I at 584 Å and Mg X at 609 Å): intermediate (6-40 min) and short (< 5 min) periods are found and are discusssed in terms of MHD waves. The Hα time series (MSDP) in both line center intensity and line-of-sight Doppler shifts provide constraints on models of filament oscillations. Title: Soho Contribution to Prominence Science Authors: Patsourakos, Spiros; Vial, Jean-Claude Bibcode: 2002SoPh..208..253P Altcode: We present the main current issues concerning prominence studies. We recall the large range of plasma parameters found in prominences which makes the work of the MHD modeler more difficult. We also summarize the capabilities of the SOHO instrumentation. We present and discuss the most recent SOHO results concerning the determination of temperature, densities, and velocities. We put some emphasis on the different morphologies observed, the diagnostic capabilities of the Lyman lines profiles when accompanied by improved non-LTE modeling, and the information gathered from the first prominence oscillations measured from space. We also make an account of eruptive prominences. We finally discuss what could be done with present and future SOHO data to improve our understanding of prominences. Title: A SUMER spectral atlas for prominences Authors: Parenti, Susanna; Vial, J. -C.; Lemaire, P. Bibcode: 2002ESASP.508..327P Altcode: 2002soho...11..327P We present preliminary results of a study aimed at building a SUMER atlas for prominences. Using the atlas as reference, further studies can be addressed at deriving prominence properties, such as DEM distribution and anomalies in element abundances. Moreover, a comparison with previous atlas (e.g. Curdt et al., 2001) of other solar regions can be made. An extended prominence was observed with SUMER in the South-West solar limb in October 1999. A full spectrum was obtained in the waveband 790 - 1600 Å. After dealing with off-limb scattered light, the data are processed using multi-Gaussian fitting in order to derive the spectral properties of the observed structure. These properties are then also compared with those of the Quiet Sun area observed in the same wavelength range. Title: Measurement of velocity fields in prominence plasma with SUMER/CDS on SOHO Authors: Cirigliano, Daniela; Vial, Jean-Claude; Rovira, Marta Bibcode: 2002ESASP.508..287C Altcode: 2002soho...11..287C Disk and quiescent prominence observations have been obtained with the CDS (Coronal Diagnostic Spectrograph) and SUMER (Solar Ultraviolet Measurement of Emitted Radiation) instruments, on board SOHO. The purpose is to investigate the macroscopic velocities of several species in the prominence plasma as compared to the quiet Sun velocities. To calculate the solar disk velocities we have taken into account the bi-modal distribution of UV structures in the quiet Sun. The macroscopic velocities in prominences were computed from the Doppler shifts in every line spectrum, taking those in the solar disk as reference. We have obtained absolute values for the macroscopic velocities ranging from 5 km/s to 40 km/s. We have also attempted to separate the central core vs. the external border behaviours of the macroscopic velocities. Title: Variation of the full Sun hydrogen Lyman α and β profiles with the activity cycle Authors: Lemaire, Philippe; Emerich, C.; Vial, J. -C.; Curdt, W.; Schühle, U.; Wilhelm, K. Bibcode: 2002ESASP.508..219L Altcode: 2002soho...11..219L Full Sun hydrogen Lyman α and β profiles obtained through the activity cycle are needed to compare with stars, to understand the hydrogen distribution in the heliosphere and to evaluate the processes in the upper planetary atmospheres. Using the SUMER/SOHO telesocope scattered light properties, we have measured the Lyman α and β profiles at different epochs of the solar activity cycle. Here we report modifications in the intensity and the shape of the profiles. Title: A Solar Cellular Automata Model Issued From Reduced MHD Authors: Buchlin, E.; Aletti, V.; Galtier, S.; Velli, M.; Vial, J. -C. Bibcode: 2002sf2a.conf..129B Altcode: A three-dimensional cellular automata model inspired by the reduced magnetohydrodynamic equations is presented to describe impulsive events generated along a coronal magnetic loop. It consists of a set of planes, distributed along the loop, between which the information propagates through Alfven waves. Statistical properties in terms of power laws are obtained in agreement with SoHO observations of X-ray bright points of the quiet Sun. Physical meaning and limits of the model are discussed. Title: Intermittent behavior in the transition region and the low corona of the quiet Sun Authors: Patsourakos, S.; Vial, J. -C. Bibcode: 2002A&A...385.1073P Altcode: We present an analysis of light-curves obtained in the O IV and Ne VIII transition region and low corona lines, that were simultaneously recorded in a quiet Sun region by SUMER/SOHO. By using the flatness spectrum of the observed light-curves we searched for intermittency signatures. It was found that a significant proportion of points in the observed area exhibit clear indications of intermittency, irrespectively of their intrinsic intensity. Our findings give favor to an impulsively heated transition region and corona via intermittent-type MHD turbulence. Title: Multiwavelength analysis of an active region observed with SOHO and TRACE Authors: Dara, H. C.; Gontikakis, C.; Zachariadis, Th.; Tsiropoula, G.; Alissandrakis, C. E.; Vial, J. -C. Bibcode: 2002ESASP.477...95D Altcode: 2002scsw.conf...95D We study the solar active region NOAA 8541, observed on May 15, 1999, from 13:00 to 15:00 UT, with the instruments aboard SOHO (SUMER, CDS, MDI) and TRACE. The SOHO observations produced a set of raster scans of the region with a field of view of 159"×120" for SUMER and of 244"×240" for CDS. TRACE gave a sequence of high time resolution images for a much larger (510"×510") field of view, in several spectral passbands, while MDI gave the photospheric full disk longitudinal magnetic field. The data set mainly covers the transition region and the low corona. We have used the data to construct intensity, velocity and magnetic field maps of the region. The comparison of the intensity images in various wavelengths with the velocity images, as well as with the magnetic field, gives us information about the dynamical characteristics of the observed features and their relationship to the photospheric magnetic field. Title: Relation between intensity and Dopplershifts in the quiet Sun transition region Authors: Gontikakis, C.; Dara, H. C.; Zachariadis, Th.; Alissandrakis, C. E.; Vial, J. -C. Bibcode: 2002ESASP.477..107G Altcode: 2002scsw.conf..107G In this work we used CDS and SUMER (SOHO) observations of a quiet region (41°W 41°N) on the 28th of July 1996. The study of the histograms of the velocities corresponding to the network and the internetwork regions, shows that the network plasma is redshifted with respect to the internetwork one. The shifts in the histograms are small, but they are systematic for all lines. It should be mentioned that the internetwork is also statistically redshifted, with the exception of the He I line. In the low transition region the morphology in the intensity images is different from the morphology in the Dopplergrams. It seems that the network intensity structures correspond to more than one in the Dopplergrams, since the latter are quite smaller than the intensity structures. This was verified by calculating the average autocorrelation function for intensity images and Dopplergrams of spectral lines from SUMER and CDS. On the average, the FWHM of the autocorrelation function of the intensity images is two times larger than that of the corresponding Dopplergram ones. Title: Cooling and evacuation of an active region loop complex observed with TRACE Authors: Tsiropoula, G.; Gontikakis, C.; Dara, H. C.; Zachariadis, Th.; Alissandrakis, C.; Vial, J. -C. Bibcode: 2002ESASP.477..179T Altcode: 2002scsw.conf..179T We analyse the temporal variation of temperature and emission measure at the top of a coronal loop system observed with the Transition Region and Coronal Explorer (TRACE). Loops delineate regions of highly localized heating and are thus typically the focus of coronal heating theories. The analyzed data consist of observations in the 171 Å and 195 Å passbands taken at a cadence of ~10 min obtained on May 15, 1999 during an observing campaign. The temperature and emission measure diagnostic is based in the 171 Å / 195 Å filter-ratio technique. The loop system evacuates after the plasma at the top of the loops has cooled. Estimates of the timescales of energy losses by radiation and by conduction clearly suggest that the cooling is mainly due to radiation losses. Title: Transition region quiet sun velocity field evolution Authors: Lemaire, P.; Artzner, G.; Vial, J. -C.; Curdt, W.; Schühle, U.; Wilhelm, K. Bibcode: 2002AdSpR..30..487L Altcode: The UV/EUV SUMER spectrometer aboard SOHO can record profiles of lines emitted by elements at different stages of ionization corresponding to several temperatures within the transition region temperature range. During the solar cycle minimum in July 1996, we were able to observe the quiet Sun during five consecutive days. From the line positions we have determined the velocity fields and follow their time variations at different temperatures in the transition region. The line intensity maps are used to separate supergranular cells and network and they allow to compare the behaviors of the velocity fields evolution in the two structures. The results are critically analyzed and discussed. Title: Observaciones del disco solar y de una protuberancia quiescente en radiación ultravioleta Authors: Cirigliano, D.; Vial, J. -C.; Rovira, M. Bibcode: 2002BAAA...45...18C Altcode: Observaciones del disco solar y de una protuberancia quiescente en el rango de longitudes de onda ultravioleta fueron obtenidas con el instrumento CDS (Coronal Diagnostic Spectrograph) y SUMER (Solar Ultraviolet Measurements of emitted radiation) a bordo de la sonda SOHO. El propósito es investigar las velocidades macroscópicas de varias especies metálicas que se observan tanto en el disco solar como en el plasma de las protuberancias. Para calcular las velocidades del disco solar aplicamos una técnica mixta para modelar la distribución de estructuras en UV en el Sol quieto. Las velocidades macroscópicas en las protuberancias se calcularon a partir de los corrimientos Doppler en cada línea espectral y luego se tomaron las del disco solar como referencia. Obtuvimos valores absolutos para las velocidades macroscópicas entre 5 y 40 km/seg. También detectamos comportamientos diferentes en las velocidades de las protuberancias en el centro con respecto a los bordes. Title: Relationships between CME's and prominences Authors: Schmieder, B.; van Driel-Gesztelyi, L.; Aulanier, G.; Démoulin, P.; Thompson, B.; De Forest, C.; Wiik, J. E.; Saint Cyr, C.; Vial, J. C. Bibcode: 2002AdSpR..29.1451S Altcode: We have studied the erupting prominences which were associated with coronal mass ejections during a series of campaigns involving both spacecraft and ground-based observatories. The evolution of the physical conditions within the prominences was established from Hα and magnetic field observations. Particular attention ahs been paid to the presence of mixed amgnetic polarity in the filament channel, the evolution of the shear of the large-scale magnetic field, and the existence of multiple magnetic inversion lines. We conclude that reconnection of large-scale coronal magnetic fields is responsible for both the CME and filament eruption. Title: Solar orbiter, a high-resolution mission to the sun and inner heliosphere Authors: Marsch, E.; Antonucci, E.; Bochsler, P.; Bougeret, J. -L.; Fleck, B.; Harrison, R.; Langevin, Y.; Marsden, R.; Pace, O.; Schwenn, R.; Vial, J. -C. Bibcode: 2002AdSpR..29.2027M Altcode: The scientific rationale of the Solar Orbiter is to provide, at high spatial (35 km pixel size) and temporal resolution, observations of the solar atmosphere and unexplored inner heliosphere. Novel observations will be made in the almost heliosynchronous segments of the orbits at heliocentric distances near 45 R⊙ and out of the ecliptic plane at the highest heliographic latitudes of 30° - 38°. The Solar Orbiter will achieve its wide-ranging aims with a suite of sophisticated instruments through an innovative design of the orbit. The first near-Sun interplanetary measurements together with concurrent remote observations of the Sun will permit us to determine and understand, through correlative studies, the characteristics of the solar wind and energetic particles in close linkage with the plasma and radiation conditions in their source regions on the Sun. Over extended periods the Solar Orbiter will deliver the first images of the polar regions and the side of the Sun invisible from the Earth. Title: Solar Orbiter: a high-resolution mission to the sun and inner heliosphere Authors: Fleck, Bernhard; Marsch, E.; Antonucci, Ester; Bochsler, Peter A.; Bougeret, J. L.; Harrison, R.; Marsden, R. P.; Coradini, M.; Pace, Oscar; Schwenn, Rainer; Vial, Jean-Claude Bibcode: 2001SPIE.4498....1F Altcode: The key mission objective of the Solar Orbiter is to study the Sun from close-up (45 solar radii, or 0.21 AU) in an orbit tuned to solar rotation in order to examine the solar surface and the space above from a co-rotating vantage point at high spatial resolution. Solar Orbiter will also provide images of the Sun's polar regions from heliographic latitudes as high as 38 degrees. The strawman payload encompasses two instrument packages: Solar remote-sensing instruments: EUV full-sun and high resolution imager, high-resolution EUV spectrometer, high-resolution and full-sun visible light telescope and magnetograph, EUV and visible-light coronagraphs, radiometers. Heliospheric instruments: solar wind analyzer, radio and plasma wave analyzer, magnetometer, energetic particle detectors, interplanetary dust detector, neutral particle detector, solar neutron detector. To reach its novel orbit, Solar Orbiter will make use of low-thrust solar electric propulsion (SEP) interleaved by Earth and Venus gravity assists. Solar Orbiter was selected by ESA's Science Programme Committee (SPC) in October 2000 as a Flexi-mission, to be implemented after the BepiColombo cornerstone mission to Mercury before 2013. This paper summarizes the science to be addressed with the Solar Orbiter, followed by brief descriptions of the strawman payload, the mission profile, and the spacecraft and ground segment designs. Title: Measuring Solar Abundances Authors: von Steiger, R.; Vial, J. -C.; Bochsler, P.; Chaussidon, M.; Cohen, C. M. S.; Fleck, B.; Heber, V. S.; Holweger, H.; Issautier, K.; Lazarus, A. J.; Ogilvie, K. W.; Paquette, J. A.; Reisenfeld, D. B.; Teriaca, L.; Wilhelm, K.; Yusainee, S.; Laming, J. M.; Wiens, R. C. Bibcode: 2001AIPC..598...13V Altcode: 2001sgc..conf...13V This is the rapporteur paper of Working Group 2 on Measuring Solar Abundances. The working group presented and discussed the different observations and methods for obtaining the elemental and isotopic composition of the Sun, and critically reviewed their results and the accuracies thereof. Furthermore, a few important yet unanswered questions were identified, and the potential of future missions to provide answers was assessed. . Title: The polar coronal holes and the fast solar wind: Some recent results Authors: Patsourakos, S.; Habbal, S. -R.; Vial, J. -C.; Hu, Y. Q. Bibcode: 2001AIPC..598..299P Altcode: 2001sgc..conf..299P We report on recent results on the source regions of the fast solar wind: the Polar Coronal Holes (PCH). They concern a comparison between the effective temperatures for a large set of different ions obtained from observations in the inner corona of PCH and from a fast wind numerical model based on the ion-cyclotron resonant dissipation of high-frequency Alfvén waves. We also report on some preliminary results from our modeling concerning the Fe/O ratio in the inner corona in PCH. . Title: Dopplershifts in the solar transition region Authors: Gontikakis, C.; Dara, H. C.; Alissandrakis, C. E.; Zachariadis, Th. G.; Vial, J. -C. Bibcode: 2001A&A...378..257G Altcode: We study the dynamics of the quiet sun transition region, using observations obtained with the SOHO CDS/NIS and SUMER spectrographs. We examine the morphology of the network as a function of temperature and we compare the intensity features with those of the dopplergrams. The velocity distributions have a different behaviour for the bright features which outline the network and the dark ones, located in the internetwork. A redshift and a smaller standard deviation are observed for the bright feature distributions relative to the dark ones. It should be mentioned that the internetwork is also statistically redshifted, with the exception of the He I line. Velocity distributions from different lines are compared. Title: Analysis of a UV Event in a Polar Coronal Hole Authors: Patsourakos, Spiros; Vial, Jean-Claude Bibcode: 2001SoPh..203...39P Altcode: We present observations of a UV event which occurred in a polar coronal hole. They were obtained by SUMER on SOHO in several chromospheric and transition region spectral lines. Its birth site was about 50 arc sec inside the limb and in a network lane showing a net outflow before its initiation. The event had an extension of about 5 arc sec along the slit, a duration of about 3 min and was characterized by a large increase of intensity together with a significant line broadening with, however, downflows of about 50 km s−1 being dominant. Proper motions with a velocity of about 10 km s−1 were also observed. The event appeared at middle transition (O vi) temperatures and it simultaneously showed up in chromospheric (O i, Ly β) and low transition region (C ii) temperatures. We discuss this event in view of different scenarios to account for it. Our event could be a part of the large family of quiet-Sun explosive events observed by Ryutova and Tarbell (2000) taking place in polar coronal holes that are triggered by magnetic reconnection in the low solar atmosphere. Title: Multi-wavelength analysis of a solar active region loop system with SOHO, TRACE and ground-based telescopes Authors: Tsiropoula, G.; Gontikakis, C.; Dara, H. C.; Zachariadis, Th. G.; Alissandrakis, C.; Vial, J. -C. Bibcode: 2001hell.confE..40T Altcode: No abstract at ADS Title: High-resolution EUV imaging and spectroscopy of the corona Authors: Patsourakos, Spiros; Vial, J. -C. Bibcode: 2001ESASP.493...13P Altcode: 2001sefs.work...13P We present a set of imagers and spectrometer which have been proposed as a strawman payload on board the Solar Orbiter mission. The scientific requirements of the mission are put in the context of the main issues presently discussed in solar physics. The on-going successful space solar missions have evidenced a very fine structuring of the solar atmosphere and its role in various processes at work for coronal heating, wind acceleration, flaring activity, etc. This is especially true for magnetic reconnection which seems to proceed at many different scales. These results point at the need of observations substantially improving both the spatial resolution and the multi-temperature (multi-wavelength) coverage. Solar Orbiter offers a unique opportunity to analyze this fine structure (e.g. the internal structure of the thin loops observed by TRACE) in closed and open fields. It will allow for a diagnostic of regions such as the magnetic network which seems to play a major role in the wind acceleration, in conjunction with in-situ observations of the ejected plasma. Title: Solar Orbiter EUV/UV wavelength selection and instrumentation - report of Payload Splinter Group 4 Authors: Harrison, R. A.; Vial, J. -C. Bibcode: 2001ESASP.493..151H Altcode: 2001sefs.work..151H We present here a summary of the discussions concerning the extreme ultraviolet (EUV) and ultraviolet (UV) wavelength selection and instrumentation for Solar Orbiter, held at the Tenerife meeting. These issues were assigned to Payload Splinter Group 4 and to the Wavelength Selection Working Group. Concerning the wavelength selection, a number of critical wavelength ranges were highlighted and discussed. Great emphasis was placed on good atmospheric coverage, from the chromosphere to the hottest coronal lines. A number of wavelength ranges were presented but the wide temperature range demands the inclusion of wavelengths longer than 912 Å as well as prime coronal lines in much shorter wavelength ranges, such as 170-250 Å. Regarding the instrumentation, the group agreed that Solar Orbiter should carry both imaging and spectroscopic capability in the EUV/UV and the two strawman instruments were presented and discussed. A number of alternatives were considered as were developments in technology, which could be of use for these instruments. Title: Solar Orbiter, a high-resolution mission to the Sun and inner heliosphere Authors: Marsch, E.; Harrison, R.; Pace, O.; Antonucci, E.; Bochsler, P.; Bougeret, J. -L.; Fleck, B.; Langevin, Y.; Marsden, R.; Schwenn, R.; Vial, J. -C. Bibcode: 2001ESASP.493D..11M Altcode: 2001sefs.workD..11M Solar Orbiter will provide, at very high spatial (35 km pixel size) and temporal resolution, novel observations of the solar atmosphere and unexplored inner heliosphere. It will achieve its wide-ranging scientific aims with a suite of sophisticated instruments through an innovative orbit design. Unprecedented observations will be made in the heliosynchronous segments of the orbits at heliocentric distances near 45 Rsolar and out of the ecliptic plane at the highest heliographic latitudes of 30° - 38°. The first near-Sun interplanetary measurements together with concurrent remote-sensing observations of the Sun and its corona will permit us to determine and understand, through correlative studies, the characteristics of the solar wind and energetic particles in close linkage with the plasma and radiation conditions in the source regions on the Sun. Solar Orbiter will deliver the first images of the polar regions and the far side of the Sun invisible from the Earth. Title: Searching the source regions of the fast solar wind in polar coronal holes: some recent SOHO/eclipse results and the potential of the Solar Orbiter Authors: Patsourakos, Spiros; Vial, J. -C. Bibcode: 2001ESASP.493..321P Altcode: 2001sefs.work..321P No abstract at ADS Title: Oscillations in an active region filament: Observations and comparison with MHD waves Authors: Régnier, S.; Solomon, J.; Vial, J. C. Bibcode: 2001A&A...376..292R Altcode: During the MEDOC Campaign 4, on October 1999, observations of a solar active region filament were carried out by the SUMER/SoHO spectrometer. A time sequence of this filament has been obtained with a duration of 7 h 30 min and with a temporal resolution of 30 s. The Fourier analysis of the line-of-sight Doppler velocities measured in the 584.33 Å HeI line allows us to detect oscillations in several ranges of periodicities (short periods: less than 5 min, intermediate periods: 6-20 min, and long periods: greater than 40 min). From a theoretical point of view, we consider the possible modes of oscillations of an active region filament. Following \cite{joa93a}, we treat the filament as a plasma slab embedded in a uniform magnetic field inclined at an angle phi to the long axis of the slab. Solving the dispersion equations for Alfvén waves and magnetoacoustic waves, primary and secondary mode frequencies appear to be non-equidistant. For the comparison between the observed and calculated frequencies, we outline an identification method of the oscillation modes in the observed filament. This identification provides a diagnostic of the filament: the angle between the magnetic field and the long axis of the slab is estimated to be 18deg, and the magnetic field strength B (G) is proportional to the square root of the density rhoo (cm-3) in the slab, B ~ 2.9 x 10-5 sqrt {rhoo}. 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. Bibcode: 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: UVCS Observations of Velocity Shear at Streamer Boundaries in the Corona Authors: Habbal, Shadia Rifai; Woo, Richard; Vial, Jean-Claude Bibcode: 2001SSRv...97....5H Altcode: Measurements of the intensities of the Ovi 1032 and 1037 Å spectral lines in the southern solar hemisphere, from 1.5 to 5 R_s, were made with the SOHO Ultraviolet Coronagraph Spectrometer (UVCS) in May 2000 close to solar maximum. The ratio of the intensity of the two oxygen lines is used as a proxy for solar wind velocity in the inner corona. White light images of the corona taken with the SOHO/LASCO-C2 during the same time period, and used to place the UVCS observations in the context of coronal structures, show streamers extending to high latitudes. The measured radial and azimuthal gradients of the intensity ratio reflect strong velocity shears in the corona with the slowest wind coinciding with the axis of streamers. Comparison of these results with ratios measured with UVCS during solar minimum indicates that the transition from fast to slow wind in the inner corona occurs within 20° of the axis of streamers at both phases of the solar cycle. Title: Quelques réflexions sur les travaux en cours de la Commission "Système Solaire et Univers lointain" du Comité National Authors: Vial, J. -C. Bibcode: 2001sf2a.conf....7V Altcode: No abstract at ADS Title: UVCS Observations of Velocity Shear at Streamer Boundaries in the Corona Authors: Habbal, Shadia Rifai; Woo, Richard; Vial, Jean-Claude Bibcode: 2001SSRv...97....8H Altcode: Measurements of the intensities of the O vi 1032and 1037 Å spectral lines in the southern solar hemisphere, from 1.5 to 5 R s, were made with the SOHO Ultraviolet Coronagraph Spectrometer (UVCS) in May 2000 close to solar maximum. The ratio of the intensity of the two oxygen lines is used as a proxy for solar wind velocity in the inner corona. White light images of the corona taken with the SOHO/LASCO-C2 during the same time period, and used to place the UVCS observations in the context of coronal structures, show streamers extending to high latitudes. The measured radial and azimuthal gradients of the intensity ratio reflect strong velocity shears in the corona with the slowest wind coinciding with the axis of streamers. Comparison of these results with ratios measured with UVCS during solar minimum indicates that the transition from fast to slow wind in the inner corona occurs within 20° of the axis of streamers at both phases of the solar cycle. Title: SOHO/SUMER observations and analysis of the hydrogen Lyman spectrum in solar prominences Authors: Heinzel, P.; Schmieder, B.; Vial, J. -C.; Kotrč, P. Bibcode: 2001A&A...370..281H Altcode: The complete hydrogen Lyman spectrum in several prominences has been observed with the UV spectrometer SUMER on-board the SOHO, during the Joint Observing Programme 107, together with other space and ground-based observatories. Based on these observations, we are able to demonstrate, for the first time, that there exists a large variety of intensities and shapes of Lyman lines in different prominences and in various parts thereof. Therefore, no ``canonical'' Lyman spectrum can be considered for modelling purposes. However, we have identified at least two representative properties of the observed spectra: in one case (May 28, 1999 prominence) we detected high integrated intensities and no reversals in lines higher than Lalpha . Another prominence (June 2, 1999) exhibited quite similar integrated intensities, but all lines have rather strongly reversed profiles. This behaviour cannot be explained in terms of standard isothermal-isobaric models and we thus consider more general models which are in pressure equilibrium with the magnetic field and which have significant prominence-corona transition region (PCTR) temperature gradients. This type of model, recently suggested by Anzer & Heinzel (\cite{anhe99}), is capable of explaining strong emission profiles without reversal. Based on extended non-LTE computations, we suggest that quite different Lyman spectra mentioned above may correspond to two types of PCTRs, one seen along the magnetic-field lines (unreversed profiles) and the other one seen across the field lines (reversed profiles). Finally, we again confirm the importance of partial-redistribution (PRD) scattering processes for Lyman lines in prominences. However, our analysis of new SUMER data also points to a critical role of the PCTR in radiative transport in these lines. 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. Bibcode: 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: SUMER/SOHO Observations of Long Period Oscillations in an Active Region Filament Authors: Régnier, S.; Solomon, J.; Vial, J. C. Bibcode: 2001IAUS..203..307R Altcode: During the MEDOC campaign #4 (October 1999), we observed an active region filament with the SUMER/SoHO spectrometer. After a global description of the active region NOAA 8725 with several instruments on board SoHO, we present a Fourier analysis of SUMER long time observations. This analysis allows to detect oscillations in several ranges of periodicities : 6-20 min, 30-40 min, and 55-150 min. We discuss these periodicities in terms of Alfvén and magnetoacoustic waves obtained in filament models developped by different authors. New MEDOC campaign (May 2000) coordinated with THEMIS (Tenerife) observatory should allow to examine the problem more closely. Title: Solar Orbiter, a High-Resolution Mission to the Sun and Inner Heliosphere Authors: Marsch, E.; Antonucci, E.; Bochsler, P.; Bougeret, J. -L.; Fleck, B.; Harrison, R.; Marsden, R.; Schwenn, R.; Vial, J. -C. Bibcode: 2001IAUS..203..565M Altcode: The scientific rationale of the Solar Orbiter (SO) is to provide, at high spatial and temporal resolution, observations of the solar atmosphere and unexplored inner heliosphere. The most interesting and novel observations will be made in the almost heliosynchronous segments of the orbits at heliocentric distances near 45 Rodot and out-of-ecliptic at the highest heliographic latitudes of 38 degrees. The SO will achieve its many and varied aims with a suite of small and innovative instruments through a clever choice of orbits. The first near-Sun interplanetary measurements together with concurrent remote observations of the Sun will permit us to determine and understand, through correlative studies, the characteristics of the solar wind and energetic particles in close linkage with the plasma and radiation conditions in their source regions on the Sun. The SO will, during the high-latitude orbital passes, provide the first observations of the Sun's polar regions as seen from outside the ecliptic and also measure the magnetic field at the poles. Title: Plasma Parameters of a Prominence Observed on October 16/17 1999 by SUMER and CDS/SOHO Authors: Madjarska, M. S.; Vial, J. -C.; Boccialini, K.; Dermendijiev, V. N. Bibcode: 2001IAUS..203..410M Altcode: The aim of our study was to confirm and enrich the results obtained so far on dynamics and diagnostics of solar prominences. A prominence observed on October 16/17, 1999 during MEDOC campaign # 4 in the frame of the updated joint observing programme 09 was studied. The main prominence plasma parameters like temperature and density were derived as well as their changes during 8 hours of observations. The relative line-of-sight velocities were obtained in the cool plasma material (SUMER, Si IV, 8 104 K) and prominence-corona transition region (SUMER, O IV, 2 105 K). Velocity and line width maps in both CDS He I 584 Å and O V 629.73 Å were derived. A study of the blend of O IV 1404.81 Å by Si IV 1404.77 Å and the second order line O III 702.31 Å was made. Title: DEM Study of Selected Quiet Sun Regions Authors: Gontikakis, C.; Landi, E.; Dara, H. C.; Alissandrakis, C. E.; Vial, J. -C. Bibcode: 2001IAUS..203..390G Altcode: In the present work EUV spectra of quiet Sun regions, observed with the Coronal Diagnostic Spectometer (CDS), are analysed in order to determine the Differential Emission Measure (DEM) of selected areas of the field of view. In particular, we study the differences between the DEM curves of the quiet Sun cell center areas, network areas and cell-network boundaries. The results are discussed in the light of theoretical models for the solar upper atmospheres. Title: Oscillations Observed in Intensity and Velocity for a Quienscent Prominence Authors: Bocchialini, K.; Costa, A.; Domenech, G.; Rovira, M.; Vial, J. -C. Bibcode: 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. Bibcode: 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 χ2 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: Outflow velocity of interplume regions at the base of Polar Coronal Holes Authors: Patsourakos, S.; Vial, J. -C. Bibcode: 2000A&A...359L...1P Altcode: We report on SUMER/SOHO observations at 1.05 Rsun of a well identified interplume region in a South Pole Coronal Hole. Combination of Doppler shifts and Doppler dimming measurements allowed to determine, for the first time, the total wind outflow velocity (~ 67 km s-1) at this height. Our calculations of the outflow velocity benefit from co-spatial and almost co-temporal observations. This large outflow velocity is a strong argument in favour of the interplumes being the main source of the fast solar wind. We find that the mass flux density through the observed interplume is 4.8 10-10 g cm-2s-1 which yields 10-15 g cm-2s-1 at 1 AU with an expansion factor of 11. Title: Multi-wavelength study of the slow ``disparition brusque" of a filament observed with SOHO Authors: Schmieder, B.; Delannée, C.; Yong, Deng Yuan; Vial, J. C.; Madjarska, M. Bibcode: 2000A&A...358..728S Altcode: A mid-latitude filament was observed before and after its eruption with SOHO (EIT, SUMER, CDS and LASCO) and with ground based observatories (Meudon and Pic du Midi) in the context of a coordinated MEDOC campaign in Orsay. The eruption was followed by a large Coronal Mass Ejection well observed by LASCO. Few hours before its eruption, the filament is partially heated (as seen in 195 Ä with EIT). The physical conditions of the filament before its eruption have been investigated by spectroscopic analysis of SUMER (the Lyman series L4 to L9) and of CDS combined with the Multi-channel Subtractive Double Pass Spectrograph (MSDP) spectra of Hα . Five hours before the eruption, large broadenings of chromospheric and transition region lines (CDS) were observed in the main body of the filament suggesting strong turbulence as well as opposite Dopplershifts on each side of the filament (Hα and He I) which could be interpreted as twist motions. The optical thickness of the filament is rather large. During the eruption the twist is largely developed as observed in 304 Ä. The Doppler shifts of the filament estimated from Lyman lines are in good agreement with the velocity of the front edge of the CME bright loop. We notice that both, the filament and the bright loop, are deviated towards the equator. This implies that they belong to the same global expansion event constrained to remain in the equatorial streamer. An X-ray bright point observed close to a filament footpoint could be the signature of reconnection process linked to the destabilization of the filament. It is interpreted in the framework of new MHD modeling of lateral filament footpoints (Aulanier & Démoulin 1998). Title: Solar Orbiter --- A High Resolution Mission to the Sun and Inner Heliosphere Authors: Fleck, B.; Marsch, E.; Schwenn, R.; Antonucci, E.; Bochsler, P.; Bougeret, J. -L.; Harrison, R. A.; Marsden, R.; Vial, J. -C. Bibcode: 2000SPD....31.0296F Altcode: 2000BAAS...32..828F The scientific rationale of the Solar Orbiter (SO) is to provide, at high spatial and temporal resolution, observations of the solar atmosphere and unexplored inner heliosphere. The most interesting and novel observations will be made in the almost heliosynchronous segments of the orbits at heliocentric distances near 45 Rsun and out-of-ecliptic at heliographic latitudes of up to 38o. By going to 45 Rsun the SO will allow remote sensing of the solar atmosphere with unprecedented spatial resolution, and the almost heliosynchronous orbit segments will permit us to disentangle spatial and temporal variations in the solar wind in close linkage with the plasma and radiation conditions in the source regions of the Sun. The strawman payload encompasses two instrument packages: Heliospheric Instruments --- high-res visible light telescope and magnetograph (<40 km), high-res X-ray/EUV imager (<30 km), high-res EUV spectrometer (<100 km), EUV and visible-light coronagraphs, solar neutron and γ -ray detectors, radiometers. Heliospheric Instruments --- solar wind analyzer, magnetometer, energetic particle detectors, IP dust detector, plasma wave analyser, radio experiment, neutral particle detector. Using solar electric propulsion (SEP) in conjunction with multiple planet swing-by manoeuvres, it will take SO two years to reach a perihelion of 45 Rsun at an orbital period of 149 days, with an inclination ranging from 6.7o to 23.4o w.r.t. the ecliptic. During an extended mission phase of about 2 years the inclination will increase to 31.7o, leading to a maximum heliographic latitude of 38.3o. The SO was one of the about 40 responses to the Call for Proposals for the next two "flexi-missions" (F2 and F3) within ESA's Scientific Programme. At its meeting on 1 March 2000, ESA's Space Science Advisory Committee recommended the Solar Orbiter among 5 other proposals for an assessment study. Launch is expected by the end of the decade. Title: 3-D Magnetic Configurations for Filaments and Flares: The Role of ``Magnetic Dips'' and ``Bald Patches'' Authors: Aulanier, G.; Schmieder, B.; van Driel-Gesztelyi, L.; Kucera, T.; Démoulin, P.; Fang, C.; Mein, N.; Vial, J. -C.; Mein, P.; Tang, Y. H.; Deforest, C. Bibcode: 2000AdSpR..26..485A Altcode: The 3-D magnetic configuration of a filament and of a low energy flare is reconstructed, using linear mag- netohydrostatic (lmhs) extrapolations. In both cases, we find observational signatures of energy release at the locations of computed ``bald patches'' separatrices, characterised by field lines which are tangent to the photosphere.The filament was observed on Sept. 25, 1996, in Hα with the MSDP on the German VTT, Tenerife, as well as in Si IV with SOHO/SUMER. It is modeled as a twisted flux-tube deformed by the magnetic polarities observed with SOHO/MDI. The shape and location of the computed dipped field lines are in good agreement with the shape of the filament and its feet observed in Hα. Some ``bald patches'' (BPs) are present where the distribution of dips reaches the photosphere. We show that some of the large scale field lines rooted in BPs can be related to bright fine structures in Si IV. We propose that the plasma there is heated by ohmic dissipation from the currents expected to be present along the BP separatrices.The flare was observed on May 18, 1994, in soft X-rays with Yohkoh/SXT, and in Hα at Mitaka (Japan). The magnetic field is directly extrapolated from a photospheric magnetogram from Kitt Peak Observatory. The intersections with the photosphere of the computed separatrices match well the bright Hα ribbons. The later are associated to three BPs, with overlaying dipped field lines. We show that enhanced densities are present in these dips, which can be correlated with dark Hα fibrils.Both cases show the importance of dipped field lines and BPs in the solar atmosphere. Energy release via ohmic dissipation as well as reconnection along BP separatrices is proposed to provide heating observed as UV brightenings in filament channels and even as small flares Title: Transport and Energy Conversion in the Heliosphere Authors: Rozelot, J. P.; Klein, L.; Vial, J. -C. Bibcode: 2000LNP...553.....R Altcode: 2000tech.conf.....R No abstract at ADS Title: Solar Prominences Observed by Soho (SUMER, CDS, EIT) and Ground-Based Observatories (GBO) Authors: Heinzel, P.; Schmieder, B.; Vial, J. C.; Rudawy, P. Bibcode: 2000AdSpR..25.1777H Altcode: We present two sets of prominence observations in higher lines of the hydrogen Lyman series (from Lδ to L-9), together with some other UV lines. These data have been obtained by the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) onboard the SOHO satellite in June 1997. Coordinated observations were also taken by other SOHO instruments: Coronal Diagnostic Spectrometer (CDS) and Extreme-Ultraviolet Imaging Telescope(EIT) and with the coronagraph of the Wroclaw University Observatory at Bialkóv, the spectrograph of the Ondřejov Observatory. We demonstrate the basic characteristics of the calibrated line profiles and compare them with the theoretical profiles computed from isothermal-isobaric models Title: Future Diamond UV Imagers For Solar Physics Authors: Hochedez, J. -F.; Verwichte, E.; Bergonzo, P.; Guizard, B.; Mer, C.; Tromson, D.; Sacchi, M.; Dhez, P.; Hainaut, O.; Lemaire, P.; Vial, J. -C. Bibcode: 2000PSSAR.181..141H Altcode: No abstract at ADS Title: Modelling of Helium Spectrum in Solar Prominences Authors: Labrosse, N.; Gouttebroze, P.; Vial, J. -C. Bibcode: 1999ESASP.448..503L Altcode: 1999mfsp.conf..503L; 1999ESPM....9..503L No abstract at ADS Title: Observational Signatures of Microscale Heating Authors: Bocchialini, K.; Aletti, V.; Vial, J. -C.; Lemaire, P. Bibcode: 1999ESASP.448..539B Altcode: 1999ESPM....9..539B; 1999mfsp.conf..539B No abstract at ADS Title: Magnetic and Dynamic Evolution of an Active Region Authors: Régnier, S.; Solomon, J.; Vial, J. C.; Amari, T.; Mickey, D. Bibcode: 1999ESASP.448..519R Altcode: 1999mfsp.conf..519R; 1999ESPM....9..519R No abstract at ADS Title: Is Flaring Activity present in the Chromospheric Network ? Authors: Cauzzi, G.; Falchi, A.; Falciani, R.; Vial, J. C. Bibcode: 1999ESASP.448..685C Altcode: 1999mfsp.conf..685C; 1999ESPM....9..685C Microflares occurring at coronal levels are one of the mechanisms proposed for the heating and dynamics of the chromospheric network. During a SOHO coordinated campaign, we acquired a set of chromospheric and transition region data, at high temporal and spatial resolution, that are suitable for such a research. We describe the characteristics of network points at several heights in the atmosphere. We look for the presence of signatures typical of flares, albeit at much smaller scales. Only one, of the 11 network points analyzed over 1 hr of observations, displays several episodes of red asymmetry in the H_α wings. These asymmetries can be interpreted as downward motions induced by the sudden compression of the lower atmosphere caused by either a particle beam or a conduction front. The analysis hence suggests that microflaring events in network points have a low occurrence probability, or that their energy flux is still below our observational capabilities. Title: Structure and Dynamics in the Transition Region Authors: Gontikakis, C. P.; Dara, H. C.; Alissandrakis, C. E.; Zachariadis, Th. G.; Vial, J. -C.; Bastian, T.; Chiuderi Drago, F. Bibcode: 1999ESASP.448..297G Altcode: 1999mfsp.conf..297G; 1999ESPM....9..297G No abstract at ADS Title: Preface Authors: Vial, J. -C. Bibcode: 1999ESASP.446....1V Altcode: 1999soho....8....1V No abstract at ADS Title: Multi-Instrument Study Of The Evolution Of An Active Region Authors: Regnier, S.; Amari, T.; Solomon, J.; Vial, J. C.; Mickey, D. Bibcode: 1999ESASP.446..571R Altcode: 1999soho....8..571R We follow, for about half a solar rotation, the dynamic evolution of an acive region (AR 8151) which exhibited a single heading sunspot and a more diffuse following magnetic flux and a filament eruption on 12 February 1998 at 13:51. For longitudinal magnetic observations, we use the MDI (SoHO) magnetograph and for vector magnetic fields the IVM (Mees Solar Observatory, Hawaii). The dynamic evolution is derived from time-sequence images in the Fe XII line (195 Angstrom) from EIT (SoHO). Density and abundance diagnostic of the filament are obtained from SoHO spectrometers (CDS, SUMER). Title: Hydrogen Lyman Lines and Continuum Emission in a Polar-Crown Prominence Observed with SUMER/SOHO Authors: Schmieder, B.; Kucera, T.; Heinzel, P.; Vial, J. -C. Bibcode: 1999ESASP.446..605S Altcode: 1999soho....8..605S We present, for the first time, a quasi-simultaneous spectroscopic observation of the whole Lyman series of HI and continuum in a quiescent prominence. Namely we have extended our previous study of higher Lyman lines to lower members of the series, particularly L-alpha and L-beta. For the latter two lines, we compare our calibrated profiles (free of geocoronal absorption) with previous data from OSO-8 LPSP spectrometer and (for L-alpha) from UVSP/SMM. We demonstrate the importance of Lyman lines for studies of the base of the prominence-corona transition region. Title: La mission solaire SOHO: quelques résultats récents Authors: Vial, J. Bibcode: 1999CRASB.327.1201V Altcode: After more than 3 years of operations, the SOHO solar mission has brought a large body of new results, the full exploitation of which continues. SOHO has provided evidence of the role of magnetic reconnection at many different spatial scales (including scales smaller than any spatial resolution) in direct heating by the Joule effect, or in generating MHD waves or accelerating particles. Reconnection seems to occur very low in the atmosphere with a permanent reshuffling of magnetic fields resulting from flux emergence at the borders of the supergranulation network. SOHO has also demonstrated the multifluid nature of the solar wind in the low corona where ion (and proton) temperatures are higher than electron temperatures. This ion heating can be explained by resonance between MHD waves and ion (and proton) gyration around the field lines. Such conclusions (and others) will be tested over the next few years with new observations from SOHO. Title: 8th SOHO Workshop: Plasma Dynamics and Diagnostics in the Solar Transition Region and Corona Authors: Vial, J. -C.; Kaldeich-Schü, B. Bibcode: 1999ESASP.446.....V Altcode: 1999soho....8.....V No abstract at ADS 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. Bibcode: 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 (6-8 104 K) and O IV 1401.156, 1404.812 (1.7-2.0 105 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 104 to 106 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: SOHO/SUMER observations and analysis of hydrogen Lyman lines in a quiescent prominence Authors: Schmieder, B.; Heinzel, P.; Vial, J. C.; Rudawy, P. Bibcode: 1999SoPh..189..109S Altcode: A quiescent prominence was observed in June 1997 by instruments onboard the SOHO spacecraft: the Solar Ultraviolet Measurements of Emitted Radiation (SUMER), Coronal Diagnostic Spectrometer (CDS) and Extreme-Ultraviolet Imaging Telescope (EIT), along with the coronagraph of the Wrocław University Observatory at Bialków and the spectrograph of the Ondřejov Observatory. We present prominence observations in higher lines of the hydrogen Lyman series (from Lδ to L-9), together with some other UV lines obtained by SUMER. We extract the basic characteristics of the calibrated line profiles of these Lyman lines and compare them with the theoretical profiles computed from three kinds of NLTE models which also include prominence filamentation. Our principal result is that the current NLTE models are in principle capable of explaining the SUMER calibrated intensities in the observed Lyman lines. We also find that in order to fit all these lines, one has to consider a prominence-corona transition region (PCTR) with a temperature gradient. At low pressures, higher Lyman lines are still rather sensitive to the incident radiation which must be carefully taken into account in the modeling. From PCTR models, which also take into account the effect of ambipolar diffusion on the heating, we have derived the formation depths for the Lyman series lines. High Lyman lines seem to be formed just at the base of the PCTR. Title: Plasma dynamics and diagnostics in the solar transition region and corona. Proceedings. Authors: Vial, J. -C.; Kaldeich-Schürmann, B. Bibcode: 1999pdds.book.....V Altcode: No abstract at ADS Title: The Coarse Versus The Fine Structure Of The Quiet-Sun Chromospheric And Transition Region Network Authors: Patsourakos, Spyridwn; Vial, J. -C.; Gabriel, A. -H.; Bellamine, N. Bibcode: 1999ESASP.446..537P Altcode: 1999soho....8..537P The chromospheric and transition region network is believed to be the basic channel of energy and momentum that heats the corona and accelerates the solar wind. While at spatial scales of one supergranular cell the network appears to be more or less homogeneous, at smaller scales it possesses a finer structure. We present here observations made with the CDS and SUMER spectrometers on SOHO pursuing the investigation of the coarse and the fine structure of the quiet-Sun network. A two-dimensional autocorrelation method allowed us to deduce the temperature-variation of network's width, while well-chosen density-sensitive line-ratios permitted to determine its filling factor at different temperatures. A discussion on possible implications of our results for steady-state energy and momentum balance for the quiet-Sun is included. Title: Multiwavelength Analysis of Network Bright Points - Coordinated Observations SOHO-GBO JOP No 37 Authors: Falchi, A.; Cauzzi, G.; Falciani, R.; Vial, J. -C. Bibcode: 1999ASPC..184..261F Altcode: We analyze the temporal behaviour of Network Bright Points (NBPs) using a set of data acquired during coordinated observations between ground based observatories (mainly at the NSO/Sacramento Peak) and the SUMER and MDI instruments onboard SOHO. We find that, at any time, all NBPs present in the NaD_2 images are co-spatial within 1" with locations of enhanced magnetic field density, and that not all the NBPs identified in the low chromosphere can be identified at higher levels. We calculate the intensity power spectrum for each NBP in several low-chromospheric signatures, such as the red wing of Hα, NaD_2 and Hα line center. The power spectra show no power at the 5.5 mHz frequency, while they display an enhancement at frequencies below 2 mHz, corresponding to periods between 8 and 20 minutes. Title: Transition-Region Network Boundaries in the Quiet Sun: Width Variation with Temperature as Observed with CDS on SOHO Authors: Patsourakos, S.; Vial, J. -C.; Gabriel, A. H.; Bellamine, N. Bibcode: 1999ApJ...522..540P Altcode: We report here the results of a study of the temperature variation of the network boundary thicknesses in the quiet-Sun transition region. A Fourier-based two-dimensional autocorrelation method has been applied to 240''×240'' rasters obtained in several transition-region lines by the CDS spectrometer on SOHO. The quantitative variation of the network boundary width with temperature has been obtained for the first time in a full two-dimensional field. It appears that network boundaries have an almost constant width up to a temperature of about 105.4 K and then fan out rapidly at coronal temperatures. This expansion of the transition-region network boundaries with temperature is found to be quantitatively in agreement with earlier theoretical models of the transition region. Title: The Role of "Magnetic Dips" and "Bald Patches" for a Filament Observed by SOHO and GBO Authors: Aulanier, G.; Schmieder, B.; Kucera, T.; van Driel-Gesztelyi, L.; Démoulin, P.; Mein, N.; Vial, J. -C.; Mein, P. Bibcode: 1999ASPC..184..291A Altcode: The studied filament was observed on Sept. 25, 1996, in Hα with the MSDP on the German VTT, Tenerife, as well as in Si IV with SOHO/SUMER. The 3-D magnetic configuration of the filament channel is reconstructed, using linear magnetohydrostatic (lmhs) extrapolations from a SOHO/MDI magnetogram, which is modified by a background magnetic component constraining a twisted flux-tube. This flux-tube is deformed by the magnetic polarities observed with SOHO/MDI. The shape and location of the computed "dipped field lines" are in good agreement with the shape of the filament and its feet observed in Hα. Some "bald patches" (BPs) are present where the distribution of dips reaches the photosphere. We find observational signatures in Si IV brightenings of energy release at the locations of computed "bald patch separatrices", defined by field lines which are tangent to the photosphere. We propose that the plasma is there heated by ohmic dissipation from the expected currents in the BP separatrices. The results show the importance of "dipped field lines" and "bald patches" in filament channels. Title: Coordinated Prominence Observations by SOHO and Ground-Based Observatories Authors: Schmieder, B.; Heinzel, P.; Vial, J. -C.; Malherbe, J. M.; Mein, P.; Rudawy, P.; Ceppatelli, G. Bibcode: 1999ASPC..184..296S Altcode: Coordinated observations obtained during the JOP12 (Joint Observing Programme between SOHO and ground-based instruments) allow us to analyse the physical conditions in a prominence of 5 June 1997 and its environment in the solar corona. The arch-shaped prominence shows either vertical or horizontal structures according to the observed lines (Hα with the coronagraph of the Wroclaw University Observatory at Bialków and lines in a broad temperature range by the Coronal Diagnostic Spectrometer CDS). The less dynamic behaviour of this prominence was shown by the persistence of bubbles in the prominence and confirmed by the Dopplershifts measured in CDS lines and in Hα by the Italian Panoramic Monochromator (IPM) filter on the THEMIS telescope in Tenerife. We explain the complex morphology of this prominence by recent 3D MHD models. Finally, we present prominence spectra in higher lines of the hydrogen Lyman series (from Lδ to L-9), together with some other UV lines. These data have been obtained by the Solar Ultraviolet Measurements of Emitted Radiation (SUMER). We demonstrate the basic characteristics of the calibrated line profiles of Lyman lines and compare them with the theoretical profiles computed from isothermal-isobaric models. This leads to some constraints on the environment of the prominence. Title: Coordinated observations between SOHO/SUMER and ground during the 1998 total eclipse: Non-thermal line broadenings and electron densities in a polar coronal hole Authors: Patsourakos, S.; Vial, J. -C.; Gabryl, J. -R.; Koutchmy, S.; Schühle, U. Bibcode: 1999AIPC..471..285P Altcode: 1999sowi.conf..285P Alfvén waves represent one of the most prominent ways of heating the solar corona and accelerating the solar wind. One of their signatures is to broaden the spectral lines in excess of their thermal width. Here we aim to combine observations of non-thermal broadenings measured by SUMER in OVI (1037.6 Å) line and electronic densities derived from white-light observations during the 1998 total eclipse. After checking the validity of the frequently-used assumption of equal ion and electron temperatures, we compute the variation of the non-thermal velocity as a function of height in an interplume region within the south polar coronal hole. Title: Filament channel structures in a SI IV line related to a 3d magnetic model Authors: Kucera, T. A.; Aulanier, G.; Schmieder, B.; Mein, N.; Vial, J. -C. Bibcode: 1999SoPh..186..259K Altcode: A recent 3D magnetic model of filament support (Aulanier and Démoulin, 1998) has shown that specific morphologies derived from the model, based on SOHO/MDI magnetograms, match quite well with the observations of a filament observed in Hα and Ca ii lines with the German telescope VTT in Tenerife on 25 September 1996 (Aulanier et al., 1998, 1999a). Some predictions of this model concern the filament channel. To continue the comparison of model and data, we have investigated the same filament region observed in ultraviolet by the SOHO spectrometers SUMER and CDS. The elongated EUV fine structures in the filament channel observed in the Si iv 1393.76 Å line by SUMER have similar orientations and locations to features predicted by the model of Aulanier et al. (1999a). These regions are near the bases of field lines which tangentially join to the photosphere in so called 'bald patches' and are parts of large arcades above the filament channel. In addition, we consider the Si iv Doppler shifts in these structures and compare them to what might be expected from the model field structure. Our study also suggests that the filament has a very low opacity in Si iv, lower than that of the O v line observed by CDS. 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. Bibcode: 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 J3= 1 min 36 s to 3 min 12 s and J4=3 min 12 s to 6 min 24 s. For all species, oscillations in the J4 band were dominant. We found relevant differences between the behavior of line D1 (1393.76 Å) corresponding to Si iv and the set D2 (1401.16 Å), D3 (1404.81 Å), D4 (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 D1 that appears in the range of 15-20 min. This disturbance seems to travel with a speed of about 170 km s−1. Title: Solar Wind Outflow and the Chromospheric Magnetic Network Authors: Hassler, Donald M.; Dammasch, Ingolf E.; Lemaire, Philippe; Brekke, Pal; Curdt, Werner; Mason, Helen E.; Vial, Jean-Claude; Wilhelm, Klaus Bibcode: 1999Sci...283..810H Altcode: No abstract at ADS Title: Oscillations of the upper chromosphere Authors: Gouttebroze, P.; Vial, J. -C.; Bocchialini, K.; Lemaire, P.; Leibacher, J. W. Bibcode: 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: Eruptive filament of May 31, 1997, observed by SOHO. Authors: Schmieder, B.; Heinzel, P.; Vial, J. -C.; Delaboudinière, J. -P.; Delannée, C. Bibcode: 1999joso.proc..147S Altcode: In the frame of the SUMER/CDS Joint Programme (JOP 17) the authors have detected the four Lyman lines in an erupting filament. The strong self-absorption in these lines, already reported for quiescent filaments, is still present in this highly dynamical event, but the authors observe a significant red asymmetry in the intensities of the two peaks. They ascribe it to an upward bulk motion of the filament, which they can actually see on a series of EIT images taken in the Fe XII line. Both sets of observations can lead to a determination of the velocity vector. The Doppler velocities are also derived from other lines detected by SUMER/CDS and can be correlated with the observations of the Pic-du-Midi MSDP obtained for this event. The filament eruption was also well observed by other GBO instruments in the Hα line (Meudon and Ondřejov). Title: Outflow Velocities at the Base of a Polar Coronal Hole During the 1998 Total Eclipse Authors: Patsourakos, S.; Vial, J. -C.; Gabryl, J. -R.; Koutchmy, S.; Schühle, U. Bibcode: 1999SSRv...87..291P Altcode: Polar coronal holes represent the most convincing site from which the high-speed solar wind originates. Here we report high-accuracy Doppler shifts measured in the O VI (1037.6 Å) line obtained by SUMER on SOHO inside an interplume region within the south polar coronal hole. We infer limits on the outflow velocity and draw hints about the flow geometry. Title: Solar chromospheric structures observed in UV ressonance lines : a multivariate analysis approach Authors: Patsourakos, S.; Bocchialini, K.; Vial, J. -C. Bibcode: 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: Study of solar prominences with data obtained with the SUMER instrument on B oard SOHO satellite. Authors: Rovira, M. G.; Costa, A.; Blanco, S.; Domenech, G.; Vial, J. C. Bibcode: 1998larm.confE..13R Altcode: The oscillations in a limb prominence have been studied through a multiresolution wavelet analysis. We found relevant differences between the behavior of Si IV and O IV lines. We also report the identification of a pulse in a range between 15-20 min. This disturbance seems to travel with a speed of about 170 km/s. Title: Filament Observations with SOHO Sumer/cds: The Behaviour of Hydrogen Lyman Lines Authors: Schmieder, B.; Heinzel, P.; Kucera, T.; Vial, J. -C. Bibcode: 1998SoPh..181..309S Altcode: On 21 September 1996, a filament close to an area of enhanced network was observed with the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) spectrometer and Coronal Diagnostic Spectrometer (CDS). CDS provided intensity, Doppler shift and linewidth maps of the region in six lines whose temperature range covers 104 to 106 K. SUMER observations consisted of maps of the region in four hydrogen Lyman lines (Lδ, L∈, L-6, L-7) and a Svi line (944 Å). In all the Lyman lines we detect a central absorption and an asymmetry in the intensity of the two peaks. First NLTE computations indicate that such reversed Lyman profiles and their absolute intensities can be reproduced with the existing filament models provided that we take into account a prominence-corona transition region (PCTR). We discuss the Lyman lines' asymmetry in terms of macroscopic flows by comparison with the Hei line Doppler shifts observed with CDS. Title: Solar chromospheric structures observed in UV resonance lines: a multivariate analysis approach. Authors: Patsourakos, S.; Bocchialini, K.; Vial, J. -C. Bibcode: 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. Bibcode: 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: Cor-I: a coronal white-light imager for a solar probe Authors: Vial, J. -C.; Koutchmy, S.; Habbal, S. R. Bibcode: 1998AdSpR..21..291V Altcode: Solar and heliospheric observations acquired over several decades, have shown that the corona is a highly structured medium. There is no doubt that these structures reflect the response of the coronal plasma - confined by the highly inhomogeneous magnetic field - to different forms of energy input. While in-situ plasma measurements have provided the characteristic properties of both fast and slow solar winds, they have fallen short in connecting them to the source regions of the wind. A near-Sun flyby mission offers an unprecedented opportunity to explore the solar wind at distances much closer to the Sun than ever achieved before. However, it is essential that in-situ measurements be coordinated with simultaneous imaging of the structures encountered in the corona. We present the concept and design of a white-light imager called Cor-I, as a key instrument for a near-Sun flyby mission which makes it possible to distinguish spatial structures from temporal changes in the plasma parameters. With the inference of the electron density from the Thomson scattered emission, white-light measurements are also a very powerful tool for quantitative studies of the acceleration region of the solar wind. In addition, the proposed instrument carries the potential for discovery of transient events and waves in these parts of the acceleration region of fast and slow solar winds that are inaccessible to in-situ plasma instruments. Title: SUMER/SOHO Filament Observations in Selected Lyman Lines Authors: Schmieder, B.; Kucera, T.; Heinzel, P.; Vial, J. -C. Bibcode: 1998ASPC..150..205S Altcode: 1998IAUCo.167..205S; 1998npsp.conf..205S 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. Bibcode: 1998ASPC..150...55C Altcode: 1998IAUCo.167...55C; 1998npsp.conf...55C No abstract at ADS Title: Solar Probe: The RAMSES Proposal Authors: Le Quéau, D.; Roux, A.; Vial, J. -C. Bibcode: 1998ESASP.417...75L Altcode: 1998cesh.conf...75L No abstract at ADS Title: Quiescent filament diagnostic. Authors: Lamartinie, S.; Bocchialini, K.; Vial, J. -C.; Chiuderi-Drago, F.; Harrison, R.; Alissandrakis, C. E. Bibcode: 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: Solar Prominence Diagnostics (Review) Authors: Vial, J. -C. Bibcode: 1998ASPC..150..175V Altcode: 1998IAUCo.167..175V; 1998npsp.conf..175V No abstract at ADS Title: Height variations of prominence plasma parameters Authors: Kotrč , P.; Heinzel, P.; Vial, J. -C.; Rompolt, B. Bibcode: 1998PAICz..88..208K Altcode: No abstract at ADS Title: 3-D Modelling of a Filament Observed in Hα and with SOHO Authors: Aulanier, G.; Schmieder, B.; Démoulin, P.; Mein, N.; van Driel-Gesztelyi, L.; Mein, P.; Vial, J. C.; Deforest, C. Bibcode: 1998ESASP.417..217A Altcode: 1998cesh.conf..217A No abstract at ADS Title: Coronal jet turbulent activity to explain distorted emission line Authors: Loucif, M. L.; Ben Jaffel, L.; Koutchmy, S.; Vial, J. -C. Bibcode: 1998ESASP.421..303L Altcode: 1998sjcp.conf..303L No abstract at ADS Title: Polar jets and plasmoids:Results from JOP 57 Authors: Delannee, C.; Koutchmy, S.; Delaboudiniere, J. -P.; Hochedez, J. -F.; Vial, J. -C.; Dara, H.; Georgakilas, A. Bibcode: 1998ESASP.421..129D Altcode: 1998sjcp.conf..129D No abstract at ADS Title: Transient Events and Their Solar Magnetic Field Authors: Vial, J. -C. Bibcode: 1998HiA....11..877V Altcode: 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 Bibcode: 1998LNP...507.....V Altcode: 1998sspt.conf.....V No abstract at ADS Title: Filament observations with SOHO SUMER/CDS. Authors: Schmieder, B.; Kučera, T.; Heinzel, P.; Vial, J. -C. Bibcode: 1998joso.proc..136S Altcode: During a coordinated campaign between SOHO and ground-based instruments a filament located close to the central meridian has been the target of SUMER and CDS spectrometers on September 21, 1996. Title: On a Possible Mechanism of Quiescent Prominence Destabilization Authors: Nenovski, P.; Dermendjiev, V. N.; Madjarska, M. S.; Vial, J. -C. Bibcode: 1998ASPC..150..354N Altcode: 1998IAUCo.167..354N; 1998npsp.conf..354N No abstract at ADS Title: Emission of hydrogen lines by moving solar prominences. Authors: Gontikakis, C.; Vial, J. -C.; Gouttebroze, P. Bibcode: 1997A&A...325..803G Altcode: We study the radiative transfer processes occurring in a plane-parallel slab standing vertically above the chromosphere and moving upward as a solid body. This structure simulates a prominence in the phase of eruption or a quiescent prominence where the plasma presents bulk velocities. We use partial redistribution for the description of the resonance scattering in the hydrogen Lα and Lβ lines. We compute the Lα, Lβ and Hα emergent line profiles of hydrogen for different velocities. We derive the variation of the emitted intensities as a function of the velocity for various temperatures and thicknesses. We discuss our results in view of the diagnostic of erupting prominences in Lyman lines that SOHO observations can provide. Title: Spectral diagnostics for eruptive prominences Authors: Gontikakis, C.; Vial, J. -C.; Gouttebroze, P. Bibcode: 1997SoPh..172..189G Altcode: 1997ESPM....8..189G The diagnostic of eruptive prominences needs the development of new tools. Here we propose the Lyman and Balmer lines of hydrogen, which are important in the radiative budget. In the NLTE radiative transfer calculations, we include the effect of the outward motion of the structure associated with the eruption of the prominence. The treatment of the resonance scattering of Lα and Lβ with partial redistribution gives higher intensities, and a higher ionization than the complete redistribution, but the two approaches converge to the same solution as the velocity increases. As a first step in the diagnostic, we present new results concerning the variation of the integrated intensities of hydrogen lines with respect to the radial velocity. Title: Formation of CA II Lines in Solar Prominences Authors: Gouttebroze, P.; Vial, J. -C.; Heinzel, P. Bibcode: 1997SoPh..172..125G Altcode: 1997ESPM....8..125G We compute the profiles of the resonance lines and infrared triplet of ionized calcium emitted by some representative models of prominences. These models consist of plane-parallel slabs of different temperatures, pressures and thicknesses, standing vertically above the solar surface. These slabs are assumed to be observed at the limb, and to be perpendicular to the line of sight. They are irradiated by the Sun on both sides, and the incoming intensities, at every relevant wavelength, are taken from observations. The model atom includes 3 stages of ionization (Cai, Caii and Caiii) with 5 discrete levels for Caii. We study the relations between emitted intensities and physical properties of the slabs, and compare the intensities emitted in Caii and hydrogen lines for the same set of models. As a result of ionization, the intensity decreases more rapidly with temperature in Caii lines than in Hi lines, so that the ratio of Caii to Hi line intensities may be used as a temperature indicator. The intensity ratio between resonance and infrared lines of Caii depends principally on the optical thickness of the structure. At high pressure and low temperature, the ratio Caii 8542Å/Hβ is found to increase with pressure. This behaviour, which is due to the saturation of Hβ, is opposite to that found by Heasley and Milkey (1978) for low pressures (optically thin structures). Title: Polar Jets and Plasmoids: Preliminary Results from JOP 57 Authors: Delannée, C.; Koutchmy, S.; Delaboudiniè, J. -P.; Hochedez, J. -F.; Vial, J. -C.; Dara, H.; Georgakilas, A. Bibcode: 1997ESASP.404..327D Altcode: 1997cswn.conf..327D No abstract at ADS Title: Dynamics of Minor Solar Activity \newline Coordinated Observations SOHO-GBO JOP #37 Authors: Cauzzi, G.; Vial, J. C.; Falciani, R.; Falchi, A.; Smaldone, L. A. Bibcode: 1997ASPC..118..309C Altcode: 1997fasp.conf..309C We present a program for coordinated observations between ground based observatories, mainly NSO/Sacramento Peak, and several instruments onboard SOHO (primarily SUMER). The scientific goal is the study of small activity phenomena, at high spatial and temporal resolution. Title: NLTE Analysis of SUMER Filament Observations on SOHO Authors: Heinzel, P.; Schmieder, B.; Vial, J. -C. Bibcode: 1997ESASP.404..427H Altcode: 1997cswn.conf..427H No abstract at ADS Title: Solar Magnetic Field Events related to CMEs observed with SOHO (MDI, EIT, SUMER, LASCO) Authors: Schmieder, B.; van Driel-Gesztelyi, L.; Wiik, J. E.; Thompson, B.; de Forest, C.; Saint Cyr, C.; Vial, J. -C.; Nitta, N.; Simnett, G. Bibcode: 1997IAUJD..19E..42S Altcode: We shall present two CMEs observed by LASCO during the minimum of activity of the Sun. These are associated with filament disparitions brusques (DB). CME and DB definitively seem to be consequences of global magnetic field instability, which causes reconnection of pre-existing field lines in the corona. We shall demonstrate how cancelling flux and converging magnetic field in photosphere may destabilize coronal streamers overlying one or two filament channels. 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. Bibcode: 1997ESASP.404..211B Altcode: 1997cswn.conf..211B No abstract at ADS Title: First Results of the SUMER Telescope and Spectrometer on SOHO - I. Spectra and Spectroradiometry Authors: Wilhelm, K.; Lemaire, P.; Curdt, W.; Schühle, U.; Marsch, E.; Poland, A. I.; Jordan, S. D.; Thomas, R. J.; Hassler, D. M.; Huber, M. C. E.; Vial, J. -C.; Kühne, M.; Siegmund, O. H. W.; Gabriel, A.; Timothy, J. G.; Grewing, M.; Feldman, U.; Hollandt, J.; Brekke, P. Bibcode: 1997SoPh..170...75W Altcode: SUMER - the Solar Ultraviolet Measurements of the Emitted Radiation instrument on the Solar and Heliospheric Observatory (SOHO) - observed its first light on January 24, 1996, and subsequently obtained a detailed spectrum with detector B in the wavelength range from 660 to 1490 Å (in first order) inside and above the limb in the north polar coronal hole. Using detector A of the instrument, this range was later extended to 1610 Å. The second-order spectra of detectors A and B cover 330 to 805 Å and are superimposed on the first-order spectra. Many more features and areas of the Sun and their spectra have been observed since, including coronal holes, polar plumes and active regions. The atoms and ions emitting this radiation exist at temperatures below 2 × 106 K and are thus ideally suited to investigate the solar transition region where the temperature increases from chromospheric to coronal values. SUMER can also be operated in a manner such that it makes images or spectroheliograms of different sizes in selected spectral lines. A detailed line profile with spectral resolution elements between 22 and 45 mÅ is produced for each line at each spatial location along the slit. From the line width, intensity and wavelength position we are able to deduce temperature, density, and velocity of the emitting atoms and ions for each emission line and spatial element in the spectroheliogram. Because of the high spectral resolution and low noise of SUMER, we have been able to detect faint lines not previously observed and, in addition, to determine their spectral profiles. SUMER has already recorded over 2000 extreme ultraviolet emission lines and many identifications have been made on the disk and in the corona. Title: High resolution solar ultraviolet measurements Authors: Lemaire, P.; Wilhelm, K.; Schühle, U.; Curdt, W.; Poland, A. I.; Jordan, S. D.; Thomas, R. J.; Hassler, D. M.; Vial, J. -C. Bibcode: 1997AdSpR..20.2249L Altcode: The increase of our understanding of the processes acting in the solar corona and maintaining it is strongly dependent on the quality of the data that are obtained to check theories. The fine structure of the solar atmosphere seen from the photosphere and extending to the hottest parts of the corona requires data with high resolution in all parameter space (angular, spectral and temporal). To constrain the hypotheses that are proposed to describe the solar corona, it is necessary to establish an accurate energy budget taking into account the processes which are acting from the chromosphere to the corona. Some requirements can be established and compared with the data collected so far (or about to be collected) with the present SUMER (Solar Utraviolet Measurements of Emitted Radiations) instrumentation. Title: Simulated white-light images of coronal structures as obtained by the CORI imager on-board a solar probe Authors: Patsourakos, S.; Vial, J. -C. Bibcode: 1997AIPC..385..129P Altcode: 1997recs.conf..129P A white-light coronal imager called CORI to be implemented on a solar probe has been proposed by Habbal et al. (1995). Its scientific objectives concern the investigation of the solar corona and the source of the solar wind. It is aimed as a complement to the in-situ instruments. This paper presents some simulations of the images that will be recorded when observing solar structures of increasing complexity during the close encounter phase of the trajectory. These attempts should be considered as a first step towards the assessment of the full scientific capabilities of CORI and the definition of the observing strategy. Title: First Results of the SUMER Telescope and Spectrometer on SOHO - II. Imagery and Data Management Authors: Lemaire, P.; Wilhelm, K.; Curdt, W.; SchÜle, U.; Marsch, E.; Poland, A. I.; Jordan, S. D.; Thomas, R. J.; Hassler, D. M.; Vial, J. C.; KÜhne, M.; Huber, M. C. E.; Siegmund, O. H. W.; Gabriel, A.; Timothy, J. G.; Grewing, M. Bibcode: 1997SoPh..170..105L Altcode: SUMER - Solar Ultraviolet Measurements of Emitted Radiation - is not only an extreme ultraviolet (EUV) spectrometer capable of obtaining detailed spectra in the range from 500 to 1610 Å, but, using the telescope mechanisms, it also provides monochromatic images over the full solar disk and beyond, into the corona, with high spatial resolution. We report on some aspects of the observation programmes that have already led us to a new view of many aspects of the Sun, including quiet Sun, chromospheric and transition region network, coronal hole, polar plume, prominence and active region studies. After an introduction, where we compare the SUMER imaging capabilities to previous experiments in our wavelength range, we describe the results of tests performed in order to characterize and optimize the telescope under operational conditions. We find the spatial resolution to be 1.2 arc sec across the slit and 2 arc sec (2 detector pixels) along the slit. Resolution and sensitivity are adequate to provide details on the structure, physical properties, and evolution of several solar features which we then present. Finally some information is given on the data availability and the data management system. Title: Low Transition-Region Characteristics of Equatorial Coronal Holes Authors: Patsourakos, S.; Bocchialini, K.; Vial, J. -C. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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-Chromosphere and Low-Transition-Region Network: a Different Organization in an Equatorial Coronal Hole? Authors: Bocchialini, K.; Vial, J. -C. Bibcode: 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: Prominence Thread Models Including Ambipolar Diffusion Authors: Fontenla, J. M.; Rovira, M.; Vial, J. -C.; Gouttebroze, P. Bibcode: 1996ApJ...466..496F Altcode: We present a study of the modeling of prominence slabs. Our models consider a collection of threads in energy balance with the surrounding corona and submitted to illumination from the underlying chromospheric layers. The models are isobaric, but temperature variations within the slab occur as a result of the energy balance constraint. We compute the non-LTE radiative transfer for a hydrogen model atom with five bound levels. The ionization is treated consistently with non-LTE radiative transfer and ambipolar diffusion (AD). The AD also affects the energy balance because of the transport of hydrogen ionization energy. We compute the emitted Lyman and Balmer spectra of our models and compare them with the observations. We find that the consideration of ambipolar diffusion increases the emission in Lyβ (and higher members of the Lyman series) as compared with the other lines. This contrasts with isothermal models that yield Lyβ emission that is too low. However, the AD models give excessive Lyβ emission, viz., too small a Lyα/Lyβ ratio compared with observations. We also compute models that include a cold core in which mechanical energy is dissipated. These models increase the Hα/Lβ ratio to values similar to the observed values for a moderate number of threads along the line of sight. However, these models still give too low a Lyα/Lyβ ratio. We conclude that the prominence observations in Lyβ show intensities that are not compatible with a steady state, field-aligned interface between the cold prominence and the hot coronal material. Also, the observations are not consistent with an isothermal slab isolated from the corona. Consequently, we suggest that at the prominence-corona interface, there is a substantial angle between the temperature gradient and the field, although this angle is significantly smaller than 90°. Title: Book reviews Authors: Humphreys, R. M.; Kemp, S.; Savonije, G.; van der Hucht, K. A.; van der Kruit, P. C.; Miley, G.; Bumba, V.; van Nieuwkoop, J.; van Hoolst, T.; Cox, A.; Rutten, R. J.; Kleczek, J.; de Jager, Cornelis; Jerzykiewicz, M.; Zwaan, C.; Poedts, S.; Sakai, Jun-Ichi; Pecker, J. -C.; Heikkila, W.; de Jong, T.; Wilson, P. R.; Müller, E. A.; Hoyng, P.; Icke, V.; Shore, S. N.; Achterberg, A.; Lucchin, F.; Butcher, H.; Ne'Eman, Y.; Heidmann, J.; Belton, M. J. S.; de Graauw, Th.; Waters, L. B. F. M.; Pacini, F.; Hultqvist, B.; Akasofu, S. -I.; Vial, J. -C.; Schatzman, E.; van der Laan, H.; Cole, K. D.; Vanbeveren, D.; Southwood, D.; van der Klis, M.; Katgert, Peter Bibcode: 1996SSRv...76..339H Altcode: No abstract at ADS Title: Cloud model with variable source function for solar Hα structures. Authors: Mein, N.; Mein, P.; Heinzel, P.; Vial, J. -C.; Malherbe, J. M.; Staiger, J. Bibcode: 1996A&A...309..275M Altcode: The "cloud model" used to derive the physical parameters of solar chromospheric features is extended to the cases of non-constant source function and of velocity gradients. This model assumes a given relationship between the source function and the opacity of the cloud which is derived from non-LTE modelling. An algorithm using 4 points of the Halpha_ profile is proposed to derive the optical thickness, the line-of-sight velocity and the dopplerwidth. The results are compared with a 5-points inversion which does not use the given relationship between source function and opacity. Effects of the uncertainty about the radiation coming from the underlying chromosphere, as well as effects of data noise, are discussed. The inversion method is illustrated by some examples of observed profiles obtained with the MSDP spectrograph of the VTT telescope (Teide Observatory). Title: A Complex Diagnostic of Solar Prominences Authors: Heinzel, P.; Bommier, V.; Vial, J. C. Bibcode: 1996SoPh..164..211H Altcode: We use the polarimetric and intensity measurements of Hα and HeI D3 lines in solar prominences to derive the true geometrical thickness for several quiescent prominences. The electron densities, derived from the collisional depolarization in Hα by Bommier et al. (1994), are used to evaluate the thickness from the emission measure. The emission measure was obtained from the theoretical correlation with the Hα integrated intensity, according to Gouttebroze, Heinzel, and Vial (1993). Theoretical electron densities obtained by latter authors are also compared with those of Bommier et al. (1994) and we find a very good agreement between them. The prominence geometrical thickness exhibits a relatively large range of values from about 100 km up to a few 104 km. The plasma densities vary by almost two orders of magnitude in the observed structures, but the total column mass in the direction perpendicular to the prominence sheet seems to be fairly constant for the set of prominences studied. Title: Prominence Eruption and Coronal Mass Ejections: Diagnostics and Future Observations from SOHO Authors: Gontikakis, C.; Vial, J. -C. Bibcode: 1996ApL&C..34..119G Altcode: No abstract at ADS Title: Two-dimensional Model of a Rotating Solar Prominence I. Observations and Preliminary Approach Authors: Kononovich, E. V.; Gorshkov, A. B.; Smirnova, O. B.; Kotrc, P.; Vial, J. -C. Bibcode: 1996ASPC...95..251K Altcode: 1996sdit.conf..251K No abstract at ADS Title: SUMER - Solar Ultraviolet Measurements of Emitted Radiation Authors: Wilhelm, K.; Curdt, W.; Marsch, E.; Schühle, U.; Lemaire, P.; Gabriel, A.; Vial, J. -C.; Grewing, M.; Huber, M. C. E.; Jordan, S. D.; Poland, A. I.; Thomas, R. J.; Kühne, M.; Timothy, J. G.; Hassler, D. M.; Siegmund, O. H. W. Bibcode: 1995SoPh..162..189W Altcode: The instrument SUMER - Solar Ultraviolet Measurements of Emitted Radiation is designed to investigate structures and associated dynamical processes occurring in the solar atmosphere, from the chromosphere through the transition region to the inner corona, over a temperature range from 104 to 2 × 106K and above. These observations will permit detailed spectroscopic diagnostics of plasma densities and temperatures in many solar features, and will support penetrating studies of underlying physical processes, including plasma flows, turbulence and wave motions, diffusion transport processes, events associated with solar magnetic activity, atmospheric heating, and solar wind acceleration in the inner corona. Specifically, SUMER will measure profiles and intensities of EUV lines; determine Doppler shifts and line broadenings with high accuracy; provide stigmatic images of the Sun in the EUV with high spatial, spectral, and temporal resolution; and obtain monochromatic maps of the full Sun and the inner corona or selected areas thereof. SUMER will be flown on the Solar and Heliospheric Observatory (SOHO), scheduled for launch in November, 1995. This paper has been written to familiarize solar physicists with SUMER and to demonstrate some command procedures for achieving certain scientific observations. Title: Some design and performance features of SUMER: solar ultraviolet measurements of emitted radiation Authors: Wilhelm, Klaus; Curdt, W.; Marsh, E.; Schuehle, Udo H.; Lemaire, Philippe; Gabriel, Alan H.; Vial, J. -C.; Grewing, Michael; Huber, Martin C.; Jordan, S. D.; Poland, Arthur I.; Thomas, Roger J.; Kuehne, Mikhael; Timothy, J. Gethyn; Hassler, Donald M.; Siegmund, Oswald H. Bibcode: 1995SPIE.2517....2W Altcode: The instrument SUMER (solar ultraviolet measurements of emitted radiation) is designed to investigate structures and associated dynamical processes occurring in the solar atmosphere from the chromosphere through the transition region to the inner corona, over a temperature range from 104 to 2 multiplied by 106 K and above. The observations will be performed, on board SOHO (solar and heliospheric observatory) scheduled for launch in November 1995, by a scanning, normal-incidence telescope/spectrometer system in the wavelength range from 500 to 1610 angstrom. Spatial resolution requirements compatible with the pointing stability of SOHO are less than 1000 km corresponding to about 1-arcsec angular resolution. Doppler observations of EUV line shifts and broadenings should permit solar plasma velocity measurements down to 1 km s-1. We report here on some specific features of this instrument related to its pointing as well as its spatial and spectral resolution capabilities. Title: Solar Physics from Ground-Based Infrared and Space Observations Authors: Vial, J. -C. Bibcode: 1995itsa.conf..221V Altcode: No abstract at ADS Title: Theoretical correlations between prominence plasma parameters and the emitted radiation. Authors: Heinzel, P.; Gouttebroze, P.; Vial, J. -C. Bibcode: 1994A&A...292..656H Altcode: Recently a set of 140 prominence NLTE models has been computed using the best available numerical techniques (Gouttebroze et al. 1993, hereafter GHV). Models are represented by one-dimensional (1D) slabs vertically standing on the solar surface and irradiated by photospheric and chromospheric radiation. They are parametrized by the gas pressure and temperature (uniform), the geometrical thickness of the 1D slab, the microturbulent velocity and the height above the solar surface. As outputs we obtained several physical quantities and optical parameters like the electron density, the total hydrogen density, the optical thickness in hydrogen lines and continua, spectral line intensities etc. (see GHV). In order to establish mutual correlations between various plasma parameters and the basic characteristics of the synthesized hydrogen spectrum, we construct some basic correlation curves. A very important relation already mentioned in GHV concerns the plasma emission measure found to be closely related to the integrated intensity of the Balmer Hα line. We present several other correlations which can be divided into four categories: (i) relations between radiation properties themselves; (ii) radiation properties versus plasma parameters; (iii) the Hα source function behaviour; and (iv) correlations between plasma parameters. Together with the 24 presented figures, we discuss the physical interpretation of these correlations and we give some hints for their application to the observed data. When appropriate, we also compare our results with existing observations. Title: About small plasmoids propagating in the solar corona Authors: Koutchmy, S.; Bouchard, O.; Grib, S.; November, L.; Vial, J. -C.; Gouttebrone, P.; Koutvitsky, V.; Molodensky, M.; Solov'iev, L.; Veselovsky, I. Bibcode: 1994ESASP.373..139K Altcode: 1994soho....3..139K No abstract at ADS Title: On the three-dimensional structure of coronal rays Authors: Koutchmy, S.; Molodenskii, M. M.; Vial, J. -C. Bibcode: 1994ARep...38..822K Altcode: No abstract at ADS Title: The Chromospheric network dynamics as derived from the analysis of CA II K and He I 1083 NM lines Authors: Bocchialini, S.; Vial, J. -C.; Koutchmy, S. Bibcode: 1994SSRv...70...57B Altcode: We present results of line profile analysis of observations simultaneously performed around the Ca II K and He I (1083 nm) lines, using the Horizontal Spectrograph of the Vacuum Tower Telescope of NSO/SP. From the spectral analysis of a 83 min long sequence of CCD spectra, we derive some dynamical properties of the main components of the quiet chromosphere: i) the magnetic network, ii) the cell interior. We present a whole set of amplitude spectra near 5 and 3 min periods for the two lines; K3 and He I velocity spectra extending up to 100 mHz are also considered, for the first time. 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. Bibcode: 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: Moon-based UV reflecting coronagraph Authors: Vial, J. C.; Koutchmy, S.; Smartt, R. N. Bibcode: 1994AdSpR..14f..43V Altcode: 1994AdSpR..14...43V UV observations of the solar disc, and above the limb, have evidenced a wide range of possible diagnostics, especially in the Lα line. On the disc, Lα traces the magnetic (sometimes unexpected) structuring of the top of the atmosphere; out from the limb, it allows measurement of radial velocities up to a few solar radii where most optical techniques fail. Other diagnostics include the kinematics of ejections (e.g. CMEs, but also small-scale rapidly evolving plasmoïds). We propose a dual-channel reflecting coronagraph combining relatively-high angular resolution (0.2-0.4'') with large spatial (2.5 solar radii from Sun center) and temporal coverage. The advantages offered by a Moon-based instrument are discussed. Title: The solar corona from SOHO Authors: Vial, J. -C. Bibcode: 1994AdSpR..14d.181V Altcode: 1994AdSpR..14..181V The heating of the solar corona and the acceleration of the solar wind are, after decades of observations and modelling, still open questions. Many processes are possible in regions of strong magnetic field, such as waves, currents, or impulsive events which involve particles acceleration. However, no conclusion has been reached up to now. The situation is no better in open field regions where a (quiet) corona also exists and the wind is faster. Apart from a theoretical effort, a coherent diagnostic of the relevant physical quantities such as densities, temperatures, velocities and their temporal and spatial variations, is necessary. We show how the coronal package on SOHO can provide the temperature and height coverage adequate to understand both small and large scale, closed and open field, solar structures. We give examples of observing programs which address some important physical problems. Finally, we emphasize the increase of scientific return if the SOHO instrumentation is considered as a unique package. Title: The SIMURIS interferometric mission: Solar physics objectives and model payload Authors: Dame, L.; Rutten, R. J.; Thorne, A. P.; Vial, J. C. Bibcode: 1994AdSpR..14d.167D Altcode: 1994AdSpR..14..167D We describe the SIMURIS Mission with emphasis on the scientific goals and related capabilities of the major instruments of the model payload. Title: Dynamical Properties of the Chromosphere In and Out of the Solar Magnetic Network Authors: Bocchialini, Karine; Vial, Jean-Claude; Koutchmy, Serge Bibcode: 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, K2V-K2R and 1083 (velocity) results differ when magnetic and non-magnetic regions are compared. Title: Very High Resolution Analysis of the Dynamics of a Coronal Plasmoid Authors: Bouchard, O.; Koutchmy, S.; November, L.; Vial, J. -C.; Zirker, J. B. Bibcode: 1994scs..conf..593B Altcode: 1994IAUCo.144..593B The authors present the results of the analysis of a movie taken over a small field of view in the intermediate corona at a spatial resolution of 0.5", a temporal resolution of 1 s and a spectral passband of 7 nm. These CCD observations were made at the prime focus of the 3.6 m aperture CFHT telescope during the 1991 total solar eclipse. Title: 'SUMER' - Solar Ultraviolet Measurements of Emitted Radiation Authors: Wilhelm, K.; Curdt, W.; Gabriel, A. H.; Grewing, M.; Huber, M. C. E.; Jordan, S. D.; Kuhne, M.; Lemaire, P.; Marsch, E.; Poland, A. I.; Schuhle, U.; Thomas, R. J.; Timothy, J. G.; Vial, J. -C. Bibcode: 1994scs..conf..619W Altcode: 1994IAUCo.144..619W SUMER is designed for the investigations of plasma flow characteristics, turbulence and wave motions, plasma densities and temperatures, structures and events associated with solar magnetic activity in the chromosphere, the transition zone and the corona. The spatial and spectral resolution capabilities of the instrument are considered in some detail, and a new detector concept is introduced. Title: Theoretical Correlations Between Various Prominence Parameters Authors: Heinzel, P.; Gouttebroze, P.; Vial, J. -C. Bibcode: 1994scs..conf..439H Altcode: 1994IAUCo.144..439H The authors present some examples of important correlations between the prominence plasma parameters and radiation properties. For example, the plasma emission measure was found to be closely related to the integrated Hα line intensity which provides a new diagnostic tool for determination of plasma densities. Title: Wave Properties in the Upper Chromosphere and at the Base of the Corona Authors: Bocchialini, K.; Vial, J. -C.; Koutchmy, S. Bibcode: 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: On the Motion of Eruptive Prominences Authors: Molodensky, M. M.; Vial, J. -C. Bibcode: 1994scs..conf..349M Altcode: 1994IAUCo.144..349M The increase of current in filaments can be evidenced by the variation of its twist. The authors show two examples of such a current increase, the last stage of which is the filament eruption and the flare. They suggest a theory of the equilibrium and the eruptive motion including the interaction of the filament current with the magnetic fields of the active region and the mirror current. They take into account the curvature of filament. Title: Analysis of Chromospheric Proxies of Coronal Bright Points Authors: Bocchialini, K.; Vial, J. -C.; Koutchmy, S.; Zirker, J. B. Bibcode: 1994ASPC...68..389B Altcode: 1994sare.conf..389B No abstract at ADS Title: Solar coronal structures Authors: Rusin, Vojtech; Heinzel, Petr; Vial, Jean-Claude Bibcode: 1994scs..conf.....R Altcode: 1994IAUCo.144.....R No abstract at ADS Title: On the 3D Solar Corona Structure Authors: Koutchmy, S.; Molodensky, M. M.; Vial, J. -C. Bibcode: 1994scs..conf..585K Altcode: 1994IAUCo.144..585K The authors consider the 3D structure of the solar corona using eclipse observations. They use a pseudostereoscopic effect of the rigidly rotating corona to determine the true position of the main coronal structures: broad threads, rays and streamers. An example of stereo-view deduced from a simple analysis of results coming from the 1991 eclipse is given. The authors conclude that large helmet streamers are composed by the pleats of the heliosphere current sheet projected on the plane of the sky. Title: Observed Chromospheric Profiles Compared with Theoretical Ones Authors: Bocchialini, K.; Gouttebroze, P.; Vial, J. -C. Bibcode: 1994emsp.conf...49B Altcode: No abstract at ADS Title: on the Three-Dimensional Structure of Coronal Rays Authors: Koutchmy, S.; Molodenskii, M. M.; Vial, J. C. Bibcode: 1994AZh....71..925K Altcode: No abstract at ADS Title: Effects of Ambipolar Diffusion on Prominence Thread Models Authors: Rovira, M. G.; Fontenla, J. M.; Vial, J. -C.; Gouttebroze, P. Bibcode: 1994scs..conf..315R Altcode: 1994IAUCo.144..315R The authors have improved previous model calculations of the prominence-corona transition region including the effect of the ambipolar diffusion in the statistical equilibrium and energy balance equations. They show its influence on the different parameters that characterize the resulting prominence theoretical structure. They take into account the effect of the partial frequency redistribution in the line profiles and total intensities calculations. Title: Analysis of the Chromospheric Proxies of Coronal Bright Points - Preliminary Results Authors: Bocchialini, K.; Koutchmy, S.; Vial, J. -C.; Zirker, J. B. Bibcode: 1994emsp.conf..173B Altcode: No abstract at ADS Title: Round Table on Solar Databases Authors: Vial, J. -C. Bibcode: 1994emsp.conf..203V Altcode: No abstract at ADS Title: Congrès Européen de Physique Solaire de Catane (Sicile). Authors: Vial, J. -C. Bibcode: 1993LAstr.107..316V Altcode: Conference on «Progrès en physique solaire», Catane (Italy), 11 - 15 May 1993. Title: Structure of coronal rays Authors: Vial, J. -C.; Molodenskij, M. M. Bibcode: 1993AZh....70.1092V Altcode: The ray structures of the corona are treated as folds and plies of magnetic surfaces with a large gradient of electron density when projected to the picture plane. The number of the intersections of the rays with an arbitrary closed contour in the projection plane is shown to be even. This allows the classification of the singular points of the observed structures. Such a classification is performed, and results of an analysis of singular points of the corona are presented for the period 1936-1984. Title: Structure of coronal rays Authors: Vial, J. -C.; Molodenskii, M. M. Bibcode: 1993ARep...37..551V Altcode: 1993SvA....37..551V No abstract at ADS Title: Two-dimensional radiative transfer with partial frequency redistribution. II. Application to resonance lines in quiescent prominences Authors: Paletou, F.; Vial, J. -C.; Auer, L. H. Bibcode: 1993A&A...274..571P Altcode: Theoretical emergent profiles in the resonance lines of H I Lyman α, Mg II h & k and Ca II H & K formed in quiescent prominences are presented. Both partial frequency redistribution effects and two-dimensional structure have been included in the calculations. The prominence model consists of a static, isobaric and isothermal freestanding slab irradiated by realistic chromospheric profiles (080-8 observations). We compare the differences between complete (CRD) and partial frequency redistribution (PRD). Vertical variations in the emergent profiles are displayed, and the importance of the geometrical effects is discussed. In addition, we have evaluated both emergent profiles for a filament as seen over the disk, and the back-scattered radiation towards the chromosphere. Title: The hydrogen spectrum of model prominences. Authors: Gouttebroze, P.; Heinzel, P.; Vial, J. C. Bibcode: 1993A&AS...99..513G Altcode: The emission of hydrogen lines and continua from solar prominences is investigated using a set of 140 simple models, covering the range of physical conditions usually assumed for these objects. These models are plane-parallel, isobaric and isothermal. The computations have been carried out using a 20 level plus continuum hydrogen atom, and taking into account the effects of partial frequency redistribution in the Lyman-alpha and beta lines. The aim of these computations is twofold: firstly, to describe the variations of hydrogen lines and continua emitted by prominences when physical conditions vary. Secondly, to provide observers with some diagnostic tool to interpret data such as intensity ratios, line widths, etc... The results of computations are given as mixed table-figure panels, each of them corresponding to a given model and summarizing the associated physical parameters and the principal features of the emitted hydrogen spectrum. Finally, for some specific parameters (or couple of parameters), we present figures illustrating the variations of these quantities across the whole set of models. Title: SUMER - Solar Ultraviolet Measurements of Emitted Radiation Authors: Wilhelm, K.; Curdt, W.; Marsch, E.; Schuehle, U.; Gabriel, A. H.; Lemaire, P.; Vial, J. -C.; Grewing, M.; Huber, M. C. E.; Jordan, S. D.; Poland, A. I.; Thomas, R. J.; Kuehne, M.; Timothy, J. G. Bibcode: 1993BAAS...25.1192W Altcode: No abstract at ADS Title: Stellar objectives of SIMURIS Authors: Damé, L.; Coradini, M.; Foing, B.; Rutten, R. J.; Thorne, A.; Vial, J. C. Bibcode: 1993MmSAI..64..345D Altcode: No abstract at ADS Title: The SIMURIS interferometric mission: solar physics objectives and model payload (invited paper) Authors: Damé, L.; Coradini, M.; Foing, B.; Rutten, R. J.; Thorne, A.; Vial, J. C. Bibcode: 1993MmSAI..64..333D 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 Bibcode: 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). Title: Radiative modeling of solar prominences, two-dimensional transfer plus partial frequency redistribution. Authors: Paletou, F.; Vial, Jean-Claude; Auer, L. H. Bibcode: 1992ESASP.348..225P Altcode: 1992cscl.work..225P The two-dimensional, PRD radiative transfer code of Auer and Paletou (1992) has been used to compute the resonance lines of H I, Mg II and Ca II in quiescent prominences, which are modeled as isothermal freestanding slabs illuminated from the sides as well as from below. Partial redistribution (PRD) and 2D effects are evidenced and compared to complete redistribution computations for both 1D and 2D geometries. Important edge variations are fround at the bottom and the top that should be observed with a spatial resolution of one arcsecond. As in 1D, PRD effects allow for greater penetration of the incident radiation into the layer. The 2D code computes both the radial emergent intensity and the amount of radiation backscattered into the chromosphere. It can, accordingly, be used to estimate the visibility of filaments. It will be of special interest to build non-isothermal models and compare e.g. the Lyα profiles with the SUMER/SOHO observations. Title: SUMER: temperatures, densities, and velocities in the outer solar atmosphere. Authors: Lemaire, P.; Wilhelm, K.; Axford, W. I.; Curdt, W.; Gabriel, A. H.; Grewing, M.; Huber, M. C. E.; Jordan, S. D.; Kuehne, M.; Marsch, E.; Poland, A. I.; Richter, A. K.; Thomas, R. J.; Timothy, J. G.; Vial, J. C. Bibcode: 1992ESASP.348...13L Altcode: 1992cscl.work...13L The SUMER instrumentation, that will be mounted on the SOHO spacecraft, is in development under MPAE leadership. It has some capability to improve the solar angular resolution and the spectral resolution already obtained in the far UV to the extreme UV, corresponding to the temperature range between 104 and a few 106K. The authors give some insights into the SUMER spectrometer that is developed to study the dynamics and to infer temperatures and densities of the low corona and the chromosphere-corona transition zone in using the 50 - 160 nm wavelength range. First, they recall the SUMER scientific goals and the technics used. Then, after a brief description of the instrumentation the expected performances are described. The way the observations can be conducted is emphasized and it is shown how SUMER is operated in coordination with other SOHO instrumentations and in cooperation with ground-based observations. Title: Structural Characteristics of Eruptive Prominences Authors: Demoulin, P.; Vial, J. C. Bibcode: 1992SoPh..141..289D Altcode: Nowadays the primordial importance of the magnetic field for coronal plasma physics is well known. However, its determination is only made in cool regions, mainly the photosphere and prominences. The extrapolation to the corona gives some indications of the magnetic structure but is not presently sufficiently reliable. So it is important to consider all the other observable physical effects of the magnetic field. Title: Model payload and system design of the SIMURIS interferometric mission Authors: Dame, L.; Rutten, R. J.; Thorne, A. P.; Vial, J. C. Bibcode: 1992wadc.iafcZ....D Altcode: SIMURIS (Solar, Solar System, and Stellar Interferometric Mission for Ultrahigh Resolution Imaging and Spectroscopy) has been proposed to ESA as a Mission in the context of the Space Station in November 1989 in answer to the Call for the Next Medium Size Mission (M2). It has completed, since, an Assessment Study, and is now proceeding for a Phase A. SIMURIS employs advanced interferometric techniques. The payload includes two major instruments which are the Solar Ultraviolet Network (SUN), an interferometric array of four 20-cm telescopes on a 2-m baseline, and the Imaging Fourier Transform Spectrometer (IFTS) which uses light from a 40-cm Gregory telescope. Both instruments have active pointing capabilities of 3 milliarcsec stability, and SUN has, in addition, an active cophasing control to 1/50th of a wavelength. EUV multilayer telescopes complete the payload for diagnostics of the very high temperature plasma. The SIMURIS model payload will be described with emphasis on the system design of the interferometric aspects of the instruments. Title: "SUMER" - Solar Ultraviolet Measurements of Emitted Radiation. Authors: Wilhelm, K.; Axford, W. I.; Curdt, W.; Gabriel, A. H.; Grewing, M.; Huber, M. C. E.; Jordan, S. D.; Kühne, M.; Lemaire, P.; Marsch, E.; Poland, A. I.; Richter, A. K.; Thomas, R. J.; Timothy, J. G.; Vial, J. C. Bibcode: 1992eocm.rept..225W Altcode: The experiment Solar Ultraviolet Measurements of Emitted Radiation (SUMER) is designed for the investigations of plasma flow characteristics, turbulence and wave motions, plasma densities and temperatures, structures and events associated with solar magnetic activity in the chromosphere, the transition zone and the corona. Specifically, SUMER will measure profiles and intensities of extreme ultraviolet (EUV) lines emitted in the solar atmosphere ranging from the upper chromosphere to the lower corona; determine line broadenings, spectral positions and Doppler shifts with high accuracy; provide stigmatic images of selected areas of the Sun in the EUV with high spatial, temporal and spectral resolution and obtain full images of the Sun and the inner corona in selectable EUV lines, corresponding to a temperature range from 104 to more than 1.8×106K. Title: The fine structure of prominences. Authors: Heinzel, P.; Vial, J. -C. Bibcode: 1992ESASP.344...57H Altcode: 1992spai.rept...57H Ground-based observations evidence in prominences a fine structure both in density and velocity fields at a subarcsec scale. The modeling of such structures is necessary in order to account for heating and cooling processes which depend critically on the geometry and the structure of the magnetic field. For a rigorous treatment of the radiative losses, one needs to solve the full NLTE problem especially in UV lines, which are critical for the energy balance. Although some attempts have already been made to model individual fine-structure elements, quiescent prominences are still mostly considered as one-dimensional structures. We discuss current improvements such as two-dimensional geometry and bundle of threads. Title: Evidence of plasmoid ejection in the corona from 1991 eclipse observations with the Canada-France-Hawaii telescope Authors: Vial, J. -C.; Koutchmy, S.; Monnet, G.; Sovka, J.; Clark, C.; Salmon, D.; Purves, N.; Sydserff, P.; Coulder, R.; November, L. Bibcode: 1992ESASP.344...87V Altcode: 1992spai.rept...87V Observations of the solar corona with a large telescope at high altitude was fully exploited with the 3.60 m CFHT (Canada France Hawaii Telescope) in Hawaii, during the 11 Jul. 1991 eclipse, are reported. Different instruments set up for the eclipse and preliminary results are given. The moving feature in the corona is focused upon. Physical conditions in this plasmoid and its origins are discussed. One of the four cameras installed in the primary focus was a video charge coupled device camera with a red filter at 637 nm selecting the red line. The power of the telescope allowed for a good signal in a pixel as small as 0.12 arcsec and a very good time resolution. The spectral resolution as measured at the Moon limb was better than one arcsec. During the three minute long sequence, 6000 video images were obtained. Among the fine structures recorded, a plasmoid about 1500 km wide was seen to ascend and dilute in the corona. Possible emission mechanisms are discussed. It was found that both low and relatively high temperature plasmas can be confined in this ejected plasmoid. Such a small scale phenomenon could be important for the heating of the corona and should be observed in UV emission lines in a wide range of temperatures. The high spatial resolution achieved by Solar Interferometric Mission for Ultrahigh Resolution Imaging and Spectroscopy (SIMURIS) allows to study the shape, stability and the diagnostics of such plasmoids in the corona. Title: Design Rationale of the Solar Ultraviolet Network / Sun Authors: Dame, L.; Acton, L.; Bruner, M. E.; Connes, P.; Cornwell, T. J.; Curdt, W.; Foing, B. H.; Hammer, R.; Harrison, R.; Heyvaerts, J.; Karabin, M.; Marsch, E.; Martic, M.; Mattic, W.; Muller, R.; Patchett, B.; Roca-Cortes, T.; Rutten, R. J.; Schmidt, W.; Title, A. M.; Tondello, G.; Vial, J. C.; Visser, H. Bibcode: 1992ESOC...39..995D Altcode: 1992hrii.conf..995D No abstract at ADS Title: SUMER - Solar ultraviolet measurements of emitted radiation Authors: Wilhelm, K.; Axford, W. I.; Gurdt, W.; Marsch, E.; Richter, A. K.; Grewing, M.; Gabriel, A. H.; Lemaire, P.; Vial, J. -C.; Huber, M. C. E. Bibcode: 1992sws..coll..129W Altcode: The SUMER (solar ultraviolet measurements of emitted radiation) experiment is described. It will study flows, turbulent motions, waves, temperatures and densities of the plasma in the upper atmosphere of the Sun. Structures and events associated with solar magnetic activity will be observed on various spatial and temporal scales. This will contribute to the understanding of coronal heating processes and the solar wind expansion. The instrument will take images of the Sun in EUV (extreme ultraviolet) light with high resolution in space, wavelength and time. The spatial resolution and spectral resolving power of the instrument are described. Spectral shifts can be determined with subpixel accuracy. The wavelength range extends from 500 to 1600 angstroms. The integration time can be as short as one second. Line profiles, shifts and broadenings are studied. Ratios of temperature and density sensitive EUV emission lines are established. Title: A solar interferometric mission for ultrahigh resolution imaging and spectroscopy: SIMURIS Authors: Damé, L.; Acton, L.; Bruner, M.; Connes, P.; Cornwell, T.; Foing, B. H.; Heyvaerts, J.; Lemaire, P.; Martić, M.; Muller, R.; Porteneuve, J.; Roca Cortés, T.; Riehl, J.; Rutten, R.; Séchaud, M.; Smith, P.; Thorne, A. P.; Title, A. M.; Vial, J. -C.; Visser, H.; Weigelt, G. Bibcode: 1991AdSpR..11a.383D Altcode: 1991AdSpR..11..383D SIMURIS is an interferometric investigation of the very fine structure of the solar atmosphere from the photosphere to the corona. It was proposed to ESA /1/, November 30 1989, for the Next Medium Size Mission - M2, and accepted in February 1990 for an Assessment Study in the context of the Space Station. The main scientific objectives will be outlined, and the ambitious model payload featuring the Solar Ultraviolet Network (SUN), a 2 m long monolithic array of 4 telescopes of Ø20 cm, and the Imaging Fourier Transform Spectrometer (IFTS), an UV and Visible Imaging Fourier Transform Spectrometer coupled to a Ø40 cm Gregory, described. Title: Solar physics at ultrahigh resolution from the space station with the Solar Ultraviolet Network (SUN) Authors: Damé, L.; Acton, L.; Bruner, M.; Connes, P.; Cornwell, T.; Foing, B.; Heyvaerts, J.; Lemaire, P.; Martić, M.; Muller, R.; Roca Cortés, T.; Riehl, J.; Rutten, R.; Title, A. M.; Vial, J. -C.; Visser, H.; Weigelt, G. Bibcode: 1991AdSpR..11e.267D Altcode: 1991AdSpR..11..267D The SUN experiment is a UV and visible Space Interferometer aimed at ultra-high resolution in the solar atmosphere. It has been proposed to ESA as part of the SIMURIS Mission Proposal which has recently been accepted for an Assessment Study in the framework of the Space Station. The 4 × 20 cm telescopes of the SUN linear array are non-redundantly placed to cover a 2 m baseline, and the instrument makes full use of stabilized interferometry potential, the 4 telescopes being co-aligned and co-phased on a reference field on the sun. After a brief outline of the scientific objectives, the concept of the instrument is described, and its image reconstruction potential is illustrated. Title: The helioseismology experiment on the Phobos planetary mission. Preliminary results Authors: Frohlich, C.; Bonnet, R. M.; Bruns, A. V.; Vial, J. C.; Delaboudiniere, J. P.; Domingo, V.; Kollath, Z.; Kotov, V. A.; Rachkovskii, D. N.; Wehrli, Ch.; Toulain, T.; Shumko, S. M. Bibcode: 1991BCrAO..83...18F Altcode: No abstract at ADS Title: Chauffage de la couronne et de la région de transition (solaires). Authors: Vial, J. -C. Bibcode: 1991sed..conf..317V Altcode: Contents: (1) Evidence d'une région externe chaude et morphologie de la couronne solaire. (2) Bilan énergétique. (3) Les sources d'énergie. (4) Couronne solaire/couronnes stellaires. Title: The helioseismological experiment at the Phobos interplanetary station - Preliminary results Authors: Froehlich, C.; Bonnet, R. M.; Bruns, A. V.; Vial, J. C.; Delaboudiniere, J. P.; Domingo, V.; Kollath, Z.; Kotov, V. A.; Rachkovskii, D. N.; Wehrli, Ch. Bibcode: 1991IzKry..83...22F Altcode: Preliminary results obtained from IPHIR (Interplanetary Helioseismology by Irradiance Measurements), a solar irradiance experiment on board the Soviet planetary mission Phobos-2, are presented. During the spacecraft's flight to Mars, the instrument gathered valuable data on tiny variations of solar irradiance over the course of six months. The data clearly show 5-min oscillations with relative amplitudes of about 10 exp -5 and with a well-defined pattern of discrete peaks in the power spectrum. The data of the red channel (it exhibited the lowest degradation of sensitivity over time) reveal remarkable temporal changes of amplitudes of discrete peaks within a period range of about 5 min, but with excellent frequency stability. Title: UV solar reflecting coronagraph Authors: Smartt, R. N.; Koutchmy, S.; Vial, J. C. Bibcode: 1990AIPC..207..578S Altcode: 1990am...proc..578S A dual-channel reflecting coronagraph is proposed that would provide observations of Lα corona and chromosphere, upper transition-region phenomena in CIV, and also helioseismology observations in the continuum around 166 nm. Each channel would use a 104×104-UV-sensitive CCD array. The combined velocity and magnetic field data would link events in the chromosphere, the transition region and the corona to an elongation of about 2.5 R0. These data would be used to study both the global-scale and also the fine-scale properties of the corona in terms of the physical processes that deposit energy and momentum in the corona. Specific question to be investigated would be the origin and morphology of CME's and other coronal transients, sources of coronal heating, and the source(s) and dynamics of the coronal wind in the inner coronal region. Title: Coming: 24 hour surveillance of the sun. Authors: Koutchmy, S.; Vial, J. -C. Bibcode: 1990Rech...21...10K Altcode: No abstract at ADS Title: Multi-Thread Structure as a Possible Solution for the L-Beta Problem in Solar Prominences Authors: Vial, J. -C.; Rovira, M.; Fontenla, J.; Gouttebroze, P. Bibcode: 1990LNP...363..282V Altcode: 1990IAUCo.117..282V; 1990doqp.coll..282V Following the pioneering works of Heasley, Mihalas, Milkey and Poland (see e.g. Heasley and Milkey, 1983) who built non LTE onedimensional models of solar prominence, much attention has been paid to the spectral signatures of the Lyman lines as observed with OSO 8 (Vial, 1982a). In spite of a better treatment of the frequency redistribution and boundary conditions, one-dimensional low-pressure models lead to Lyman intensities much lower than observed ones (Heinzel, Gouttebroze and Vial, 1987). Different atomic processes of formation of hydrogen lines (Cooper, Ballagh and Hubeny, 1988) or the inclusion of a Prominence Corona Transition Region or PCTR (Heinzel, Gouttebroze and Vial, 1988) have been proposed to explain this discrepancy. We present here a different approach where the filamentary nature of prominences which provides the hydrogen lines with different opacities, offers their photons different escaping possibilities. The thread models we use derive from an energy equation where radiative losses are balanced by conductive flux (Foutenla and Rovira, 1983, 1985). We show that no superposition of threads gives good values of Lyman a, and H a intensities for too high and too low pressures. Solutions are found for pressure around 0.05-0.1 dyn/cm2 and a number of threads between 100 and 400. Two improvements have been performed: first, the inclusion of Partial Redistribution leads to a decrease of L (and L) intensity and models now require a higher number of threads; second, the inclusion of the ambipolar diffusion along the steep temperature gradient which changes the hydrogen ionization in the lower regions (Foutenla, Avrett and Loeser, 1990). The new run of temperature and density implies more material at low temperatures and hydrogen lines intensities increase. A solution for the L problem can be found for a pressure of about 0.1 dyn cm-t2. However the H intensity appears to be rather high. Moreover, the number of threads required (about 200) is far larger than the number derived by Zirker and Koutchmy (this issue) and Mein (this issue) from observed H profiles. Our neglect of the radiative interaction between threads may explain our results (Heinzel, this issue). To conclude, these computations of non-lte radiative transfer in realistic geometrical and physical models, appear to be a promising path for the investigation of solar prominences. Title: High Resolution Solar Physics from the Space Station with Interferometric Techniques: The Solar Ultraviolet Network (SUN) - Instrument &Objectives Authors: Damé, L.; Acton, L.; Bruner, M.; Connes, P.; Cornwell, T.; Foing, B.; Heyvaerts, J.; Jalin, R.; Lemaire, Ph.; Martic, M.; Moreau, B.; Muller, R.; Roca Cortés, T.; Riehl, J.; Rutten, R.; Title, A. M.; Vial, J. -C.; Visser, H.; Weigelt, G. Bibcode: 1990PDHO....7..262D Altcode: 1990dysu.conf..262D; 1990ESPM....6..262D No abstract at ADS Title: The Prominence / Corona Interface Authors: Vial, J. -C. Bibcode: 1990LNP...363..106V Altcode: 1990IAUCo.117..106V; 1990doqp.coll..106V The existence of cool and dense material in the hot and diluted corona implies specific mass and energy transfers between the two media. This is true for all steps in prominence lifetime : formation, quiescence and disappearance. Much theoretical work has been done recently on the formation by coronal condensation, but observational signatures are scarce, probably because of the long duration involved. On the contrary, the Disparition Brusque phenomenon has been observed in different wavelengths (temperatures) and shown to be either essentially magnetic or thermal. Line ratios have been used for the density diagnostics of eruptive prominences and point to a small filling factor. As for the quiet PCTR, the increase of Differential Emission Measure at lower temperatures, extensively studied with Skylab, is still a puzzle. With the help of both u-v (HRTS) and radio (VLA) new data, temperature gradients have been derived. The DEM increase could be explained by such heating process as waves or transients and also (at low temperature) by the reduction of radiative losses in optically thick lines. UVSP,observations on SMM indicate upflows and downflows in the PCTR. Their positions with respect to the magnetic field lines are unknown simply because no magnetic measurement exists in the PCTR. There is much activity in modeling prominences as a superposition of fine structures (threads, loops,..) in thermal equilibrium and in comparing with the uv emission. Obviously, we now have some information on pressure and temperature gradient in the PCTR but we do not know the geometry, the magnetic field nor the heating process. Further decisive progress will be made with the spectrometers and coronagraphs on SOHO. Title: Comparison of Ly-α and Ly-β interplanetary glows observed by the Voyager ultra-violet spectrometer. Authors: Chassefiere, E.; Lallement, R.; Bertaux, J. L.; Vial, J. C.; Sandel, B. R. Bibcode: 1990phoh.coll...65C Altcode: The comparison between Ly-α and Ly-β glows exhibits significant discrepancies which can not be explained by radiation transfer in the Ly-α interplanetary line. They might be due, at least partially, to the temporal variability of the solar flux, larger at Ly-α center than at Ly-β center. Title: Fine structure observation in a solar prominence Authors: Lemaire, P.; Samain, D.; Vial, J. C. Bibcode: 1990AdSpR..10i.191L Altcode: 1990AdSpR..10..191L The high resolution balloon spectrograph (RASOLBA) has obtained ultraviolet prominence spectra during its September 19th, 1986, flight. The high resolution spectra (one arcsecond along the 30 arcseconds spectrograph slit length, and 0.0015 nm spectral resolution within the 20 nm wavelength band) have been recorded on film. The wavelength band was centered on the Mgll h and k (279.6 nm and 280.3 nm) resonance doublet lines inside the cross-dispersion echelle spectrograph.

The analysis of the prominence spectra shows evidence of sheared velocities (up to 20 km/s) which very within few arcseconds with the distance above the limb. This shear may appear inside magnetic loops confining the prominence material. We present the observations and a preliminary analysis of the data. Title: Le Soleil 24 Heures Sur 24 Authors: Koutchmy, S.; Vial, J. Bibcode: 1990Rech..217...10K Altcode: No abstract at ADS Title: Réunion "SOHO-Couronne" des investigateurs français sur les instruments coronaux de SOHO. Authors: Vial, J. C. Bibcode: 1989JAF....35...18V Altcode: No abstract at ADS Title: 6 - 20 mars 1989: deux semaines d'intense activité pour une seule région solaire. Authors: Vial, J. -C. Bibcode: 1989LAstr.103..203V Altcode: No abstract at ADS Title: Protuberanzen und Beobachtungsprogramme. Authors: Malherbe, J. -M.; Martres, M. -J.; Vial, J. -C. Bibcode: 1989Sonne..13....8M Altcode: No abstract at ADS Title: SUMER - Solar ultraviolet measurements of emitted radiation. Authors: Curdt, W.; Wilhelm, K.; Axford, W. I.; Marsch, E.; Richter, A. K.; Gabriel, A. H.; Lemaire, P.; Vial, J. -C.; Grewing, M.; Huber, M. C. E.; Jordan, S. D.; Poland, A. I.; Thomas, R. J.; Timothy, J. G. Bibcode: 1989AGAb....2...14C Altcode: 1989amt..conf...14C No abstract at ADS Title: Multithread Structure as a Possible Solution for the L-beta Problem in Solar Prominences Authors: Vial, J. C.; Rovira, M.; Fontela, J.; Gouttebroze, P. Bibcode: 1989HvaOB..13..347V Altcode: No abstract at ADS Title: Particles and energy transport in the solar atmosphere during solar flares. Authors: Heristchi, D.; Raadu, M. A.; Vial, J. -C.; Malherbe, J. -M. Bibcode: 1989sasf.confP.321H Altcode: 1988sasf.conf..321H; 1989IAUCo.104P.321H The proposed model of particle transport in the solar atmosphere during flares consists in a low density plasmoid originating deep in the atmosphere and rising under magnetic and buoyancy forces. Confined particles are selectively released during the ascent and their interaction with the solar atmosphere produces X and γ bremsstrahlung. The characteristics of high energy particles released in the interplanetary medium are found to agree with observations. Title: The diagnostic and modelling of the solar atmosphere through non-LTE radiative transfer: some results and prospects. Authors: Gouttebroze, Pierre; Vial, Jean-Claude; Lemaire, P. Bibcode: 1989mse..proc..245G Altcode: The authors describe new results from non-LTE radiative transfer calculations for solar UV continua and line profiles. The new non-LTE codes include partial frequency redistribution in the lines, moving atmospheres with differential velocities, and can treat finite objects with external irradiation (loops, prominences). Selected examples are given for: (1) a static atmosphere (plage); (2) a moving atmosphere (waves); and (3) free standing slabs (prominences). Title: IPHIR: The helioseismology experiment on the PHOBOS mission. Authors: Fröhlich, C.; Bonnet, R. M.; Bruns, A. V.; Delaboudinière, J. P.; Domingo, V.; Kotov, V. A.; Kollath, Z.; Rashkovsky, D. N.; Toutain, T.; Vial, J. C.; Wehrli, C. Bibcode: 1988ESASP.286..359F Altcode: 1988ssls.rept..359F IPHIR (InterPlanetary Helioseismology by IRradiance measurements) is a solar irradiance experiment on the USSR planetary mission PHOBOS to Mars and its satellite Phobos. The experiment is a cooperative effort of PMOD/WRC, LPSP, SSD/ESA, KrAO and CRIP. The sensor is a three channel sunphotometer (SPM) which measures the solar spectral irradiance at 335, 500 and 865 nm with a precision of better than 1 ppm. A two axis solar sensor (TASS) is added to monitor the moderate solar pointing of the spacecraft. A microprocessor based data processing unit controls the sensor operation, acquires the data, and performs the data compression for the transmission at a mean rate of 1 bit/s. The two spacecrafts have been launched on July 7th and 12th, 1988. The experiment on PHOBOS I gathered data during 45 days before the S/C was lost, the one on PHOBOS II is still operating. The data recovery is excellent with virtually 100% coverage. Although the signal is disturbed by the pointing of the spacecraft the results of a preliminary analysis in the range of the 5-minutes oscillations demonstrate the improvement achievable due to the fact that the time series is truly continuous and the instrumental and sampling noise is very low. Title: Non LTE modelling of prominences. Authors: Heinzel, P.; Gouttebroze, P.; Vial, J. -C. Bibcode: 1988dssp.conf...71H Altcode: The authors present the results on non-LTE computations performed in the major lines and continua of the hydrogen atom. The prominence is represented by a slab illuminated by the neighbouring chromosphere and corona. Classical models are recomputed and it appears that the low pressure model represent well the observed Lα profiles. However the Lβ-computed value is much lower than the observed one. Preliminary computations where a transition region to the corona is included that the Lβ line may be improved. Title: Two Solar Observation Programmes Authors: Marthes, M. J.; Malherbe, J. M.; Vial, J. Bibcode: 1988scaa.conf..175M Altcode: 1988IAUCo..98..175M No abstract at ADS Title: The O VI (103.2 nm) prominence profile and the prominence-corona interface. Authors: Vial, J. -C. Bibcode: 1988dssp.conf..181V Altcode: Few lines profiles have been obtained up-to-now in the transition region between prominences and corona (PCTR hereafter). The major source of information has been Skylab UV intensities. Important results concern: the presence of cool absorbing material as in the corona, the evidence of numerous (about 8) PCTRs, the similarity between differential emission measures of the chromosphere-corona transition region and the PCTR, especially in increase towards lower temperatures. However in the absence of profiles measurements, the run of temperature, densities and microturbulence could not be derived in the PCTR. Title: Formation of the hydrogen spectrum in quiescent prominences - One-dimensional models with standard partial redistribution Authors: Heinzel, P.; Gouttebroze, P.; Vial, J. -C. Bibcode: 1987A&A...183..351H Altcode: One-dimensional isothermal-isobaric static slab models are used to study departures from complete frequency redistribution (CRD) in hydrogen lines for quiescent solar prominences. Partial redistribution (PRD) effects on the hydrogen L-alpha line are shown to be significant in the near wings in addition to the far wings of L-alpha. It is suggested that strong symmetrical peaks found in the theoretical PRD L-alpha profiles are due to partially coherent penetration of the incidence double-peaked solar L-alpha. The present results are found to be consistent with OSO-8/LPSP observations and with UVSP/SMM data. The possible interplay between the effects of lateral transport or radiation, level-interlocking, and PRD is considered. Title: Protubérances solaires et programmes d'observation. Authors: Malherbe, Jean-Marie; Martres, Marie-Josephe; Vial, Jean-Claude Bibcode: 1987LAstr.101..321M Altcode: The observed characteristics of solar prominences are reviewed, and models for the formation of filaments and for the magnetic structure of protuberances are discussed. Data suggest that coronal filaments are formed either by the pumping of chromospheric matter or by condensation of the coronal plasma itself by thermal instability. The class of Kippenhahn-Schluter models involve magnetic rings which are bent under the influence of gravity, and the class of Kuperus-Raadu models place prominences above a certain neutral point. Observations of filamentary velocity fields indicate that the magnetic support of the condensation is in quasi-static evolution. Three proposed areas of study of prominences, the connections and exchanges of matter at great distances, eruptive prominences, and the sudden disappearance of prominences, are discussed. Title: Structures fines chromosphériques: nouveaux résultats de la caméra de la région de transition. Authors: Foing, B. H.; Dame, L.; Vial, J. C.; Gouttebroze, P.; Martic, M.; Bonnet, R. M. Bibcode: 1987JAF....29...15F Altcode: No abstract at ADS Title: La haute résolution en physique solaire: perspectives pour l'avenir. Authors: Damé, L.; Foing, B.; Vial, J. C. Bibcode: 1987JAF....29...16D Altcode: No abstract at ADS Title: Simultaneous measurements of chromospheric lines in sunspot umbra andpenumbra. Authors: Vial, J. -C.; Bellout, A. Bibcode: 1987PAICz..66..215V Altcode: 1987eram....1..215V The author reports on simultaneous profiles measurements obtained in the Lα, Lβ, Mg II and Ca II lines in a sunspot umbra and penumbra, performed with the L.P.S.P. instrument on OSO 8. They aim at providing some new information on both oscillations and thermodynamic structure of sunspots. Title: The OVI 103.2-NM Prominence Profile and the Prominence / Corona Interface Authors: Vial, J. C. Bibcode: 1987dssp.work..181V Altcode: 1987ASSL..150..181V No abstract at ADS Title: Non-Lte Modelling of Prominences Authors: Heinzel, P.; Gouttebroze, P.; Vial, J. C. Bibcode: 1987dssp.work...71H Altcode: 1987ASSL..150...71H No abstract at ADS Title: Observations spatiales solaires. Authors: Vial, J. C. Bibcode: 1987JAF....29...15V Altcode: No abstract at ADS Title: Diagnostics and structure. Authors: Vial, J. C. Bibcode: 1986NASCP2442...89V Altcode: The structure of prominences and the diagnostic techniques used to evaluate their physical parameters are reviewed and discussed. Title: Partial redistribution effects in the formation of hydrogen lines in quiescent prominences. Authors: Heinzel, P.; Gouttebroze, P.; Vial, J. C. Bibcode: 1986NASCP2442..155H Altcode: 1986copp.nasa..155H Departures from complete frequency redistribution (CRD) in hydrogen lines are investigated for solar prominences. Partial redistribution effects (PRD) are found both in the wings (their already known lowering) and in the central part of the L alpha line; a new feature is evidenced here: the partially coherent scattering in the near wings of the line leads to a double-peaked profile mirroring the incident solar radiation. With a low density model, we obtain a good agreement with OSO 8 observed profiles. On the contrary, the PRD computed L beta profile (lower density, no reversal) departs from the observed one, a result which calls for more progress in terms of non-LTE transfer and modelling. Title: Dynamical properties of a pre-perihelion comet tail. I. December 6, 1985 observations of P/Halley 82i. Authors: Guerin, P.; Koutchmy, S.; Vial, J. C. Bibcode: 1986A&A...167..395G Altcode: Wide field pictures of comet P/Halley 1982i obtained every hour on December 6, 1985, have been analyzed in order to study the dynamics of low intensity plasma structures in the tail. The deduced radial velocities increase from 50 to 80 km s-1 over distances of 2 to 6×106km. The measured apparent aberration angle is interpreted as a result of a large polarward solar wind velocity component. Title: Non-LTE models of solar prominences Authors: Heinzel, P.; Vial, J. C.; Gouttebroze, P.; Rompolt, B. Bibcode: 1986CoSka..15..183H Altcode: The authors briefly review some representative non-LTE models of solar prominences, developed during the past decade. Particular attention is devoted to recent interpretation of hydrogen Lyman α line profiles in quiescent prominences and to the solution of the non-LTE problem for moving active prominences. Finally, the authors outline some of the most important prospects of prominence plasma diagnostics. Title: Emission of Lyman alpha radiation by solar coronal loops. I - General synopsis Authors: Gouttebroze, P.; Vial, J. C.; Tsiropoula, G. Bibcode: 1986A&A...154..154G Altcode: The processes of emission of Lyman-alpha radiation by loop-like structures embedded in the solar corona are investigated, for a large range of physical conditions within these objects. The coupled set of equations for radiative transfer, and hydrogen atom level populations, ionization and pressure equilibria is solved to obtain the emitted L-alpha intensities as functions of pressure, temperature and size. Three different cases are treated: (1) optically thin structures with arbitrary geometry. (2) plane-parallel slabs, either horizontal or vertical, with arbitrary optical depth. (3) cylindrical loops with horizontal axis, for moderate optical depths (au is less than 1000). The importance of geometry, as well as that of partial frequency redistribution and of the hydrogen atom's model, are evaluated. Empirical formulae and diagrams of intensity as a function of physical state parameters are given. The diagnostic possibilities of Lyman-alpha filtergrams alone or in conjunction with other observations, are discussed. Title: On the origin of the blue continuum of white-light flares Authors: Dame, L.; Vial, J. -C. Bibcode: 1985ApJ...299L.103D Altcode: A new model for white-light flares is proposed in order to explain the observed blue continuum (i.e., the higher contrast longward of the Balmer jump, around 4000 A). Its broad temperature plateau between 60,000 and 90,000 K is compatible with chromospheric evaporation. The predicted UV emission, computed here in the Si IV resonance lines (1402 and 1393 A), is, however, too large by two orders of magnitude, as compared to the emission from weak flares. Because of the lack of a comprehensive set of measurements in white-light flares, the validity of such a model is still open. Title: Periodic Comet Halley (1982i) Authors: Jewitt, D.; Meech, K.; Ricker, G.; Lamy, P.; Koutchmy, S.; Vial, J. C. Bibcode: 1985IAUC.4148....1J Altcode: D. Jewitt, K. Meech, and G. Ricker, Massachusetts Institute of Technology, communicate: "Observations from McGraw-Hill Observatory on Kitt Peak over 4 nights show variable structures in the inner coma of P/Halley. Images were taken through broad and narrowband interference filters using the MIT 'MASCOT' CCD camera on the 1.3-m telescope. Jet-like structures were observed in position angles 358 and 313 on Nov. 29 UT. The jets extended 10 000 km in the plane of the sky and had widths comparable to the atmospheric seeing. The jets were visible in both broad and narrowband continuum filters and are probably dust features. The jets showed no variation in position angle or brightness in an observing interval of > 3 hr but were absent on the preceding and following nights." Meech and Jewitt also report: "Observations of P/Halley with the Kitt Peak 0.61-/0.91-m Schmidt telescope (with baked IIIa-J plates and exposure times 30-60 min) show that extensive tail development has occurred within the past month. Observations on Nov. 6-9 showed only a transient, faint anti-solar tail (length 20' on Nov. 6.20) which faded in < 1 day. Observations on Dec. 4-8 show a persistent plasma tail (length > 2.5 deg) displaying a classical streamer morphology. We are able to follow knots, kinks, and streamers in the tail for up to 6 hr. The measured speeds of 3 tail knots are 190, 216, and 240"/hr (39, 45, and 50 +/- 5 km/s along the tail, km/s), considerably less than the solar wind speed but similar to the speeds measured in the tails of other comets. No evidence for acceleration of the features is seen. Two episodes of ray formation have been seen in 25 hr of observation; the rays form in ~ 1 hr and evolve over several hr, but fade in < 18 hr. The tail as a whole shows gross brightness changes from night to night. No dust tail is seen." P. Lamy, Laboratoire d'Astronomie Spatiale, Marseille, and S. Koutchmy, Institut d'Astrophysique, Paris, telex: "Four consecutive 1-hr-exposure IIIa-J hypered plates obtained between Dec. 6.79-6.96 UT by Koutchmy and J. C. Vial with the 0.62-m f/3 Schmidt telescope of Haute Provence Observatory show a disturbed, narrow, plasma tail of length > 2 deg. The tail's inner part deviates southward from the anti-solar direction by 4.8 +/- 0.7 deg; the outer part widens and nears the anti-solar direction. The point of bifurcation seems to move radially outward with time." Title: Transfer of Lyman-α radiation in solar coronal loops. Authors: Gouttebroze, P.; Vial, J. -C.; Tsiropoula, G. Bibcode: 1985ASIC..152..359G Altcode: 1985pssl.proc..359G The emission and scattering of Lyman-α radiation within the loop-like structures of the solar corona are investigated, for a large range of physical conditions within these objects. Results from partial and complete redistribution computations are compared. A series of predictions, concerning line profiles, integrated intensities, and directional diagrams are given for observation diagnosis. Title: Le satellite S.M.M. (Solar Maximum Mission). Un observatoire tout entier consacré à l'activité solaire. Authors: Vial, J. -C. Bibcode: 1984LAstr..98..211V Altcode: The instrumentation on-board the SMM is described, together with data gathered up to November 1980. The SMM carries a gamma ray spectrometer, two hard X ray spectrometers, an X ray polychromator, an UV spectrometer polarimeter, a coronograph/polarimeter and a radiometer. The observational data linked the eruption processes with the appearance of parasitic magnetism, the disappearance of a filament, plasma temperature enhancement to 50,000 K, an increase in the 6 cm flux continuum and hard X ray emission. Measurements have confirmed a two-stage flux acceleration, with highest temperatures happening before peak emissions. The deeper understanding of solar flux phenomena gained with the SMM has been due in large part to an internationally cooperative effort to confirm space-based observations with ground-based measurements. Title: Simultaneous H and K Ca ii, h and k Mg ii, Lα and Lβ H i profiles of the April 15, 1978 solar flare observed with the OSO-8/L.P.S.P. experiment Authors: Lemaire, P.; Choucq-Bruston, M.; Vial, J. -C. Bibcode: 1984SoPh...90...63L Altcode: Solar flare observations have been performed with the multichannel L.P.S.P. experiment on board OSO-8 NASA Satellite. Simultaneous H and K CaII, h and k MgII, Lα and Lβ HI profiles have been recorded on the plage just before the flare, during the flare onset and relaxation phases. The different behaviour of line profiles and intensities during the flare is evidenced and indicates a downward propagation with relaxation times increasing from the upper part to the lower part of the chromosphere related to line formation processes. Using the Hɛ observed profile, an upper limit of 8 × 1013 cm-3 is derived for the electron density. Title: Simultaneous H and K CAII H and K MGII L-Alpha L-Beta HI Profiles of a Solar Flare Observed with OSO-8 L.P.S.P. Spectrometer Authors: Lemaire, P.; Choucq-Bruston, M.; Vial, J. C. Bibcode: 1984apoa.conf..266L Altcode: No abstract at ADS Title: Dynamics of a surge observed in the C IV and H alpha lines Authors: Schmieder, B.; Mein, P.; Vial, J. -C.; Tandberg-Hanssen, E. Bibcode: 1983A&A...127..337S Altcode: Time sequences of a surge have been obtained in Active Region 2701 during a coordinated SMY program, on October 2nd, 1980, while the MSDP spectrograph operated in H-alpha at the Meudon Solar Tower and the UVSP spectrometer on SMM observed in the 1548 A C IV resonance line. The cold (H-alpha) and hot (C IV) material follow the same channel, and the event lasts about 10 min in both lines. A good correlation is found between H-alpha and C IV velocities; radial velocities along the surge are in the range 40-60 km/s in both cases. The observations are consistent with the hypothesis that a pressure gradient drives the surge. The H-alpha data seem to indicate the presence of a shock wave in the chromosphere, while the C IV quantities (velocities, accelerations) vary on a very short time scale. Their maxima occur at some locations which could be interpreted as 'pinched' zones. Title: OSO-8 observations of a quiescent prominence - A comparison of Lyman-alpha with theoretical intensities Authors: Heinzel, P.; Vial, J. -C. Bibcode: 1983A&A...121..155H Altcode: Using simultaneous observations of hydrogen Lyman-α and Ca II K lines obtained with the OSO 8 LPSP instrument, the authors compare Lα emission from a quiescent prominence with those predicted from the existing theoretical models. They use the observed relation between Hα and Ca II K integrated intensities to obtain an estimate of E(Hα)/E(Lα) vs. E(Hα). This ratio differs significantly from those predicted theoretically under the assumption of complete frequency redistribution during the scattering of Lα photons. On the other hand, using the partial-redistribution treatment in the Lα wings, as suggested by Milkey et al., the authors arrived at a reasonable agreement with the corresponding theoretical curve. The possible influence of macroscopic velocities on line ratios is briefly discussed. Title: Structure and Physics of Solar Faculae - Part Three - the Densities in the Chromosphere-Corona Transition Zone Authors: Dumont, S.; Mouradian, Z.; Pecker, J. -C.; Vial, J. -C.; Chipman, E. Bibcode: 1983SoPh...83...27D Altcode: Si IV, C IV, and O VI resonance lines have been measured above quiet and active solar regions from both pointed OSO-8 instruments. From calibrated profiles, optical depths are computed with three different methods. All three methods provide evidence that the opacity above faculae is lower than above the quiet Sun. Title: Measurements of solar transition zone velocities and line broadening using the ultraviolet spectrometer and polarimeter on the Solar Maximum Mission Authors: Simon, G.; Mein, P.; Vial, J. C.; Shine, R. A.; Woodgate, B. E. Bibcode: 1982A&A...115..367S Altcode: The UVSP instrument on SMM is able to observe solar regions at two wavelengths in the same line with a band-pass of 0.3 A. Intensity and Doppler velocity maps are derived. It is shown that the numerical values are sensitive to the adopted Doppler width and the range of velocities is limited to within 30 km/sec. A method called Double Dopplergram Determination (DDD) is described for deriving both the Doppler width and the velocity (up to 80 km/sec), and the main sources of uncertainties are discussed. To illustrate the method, a set of C IV 1548 A observations is analyzed according to this procedure. The mean C IV Doppler width measured (0.15 A) is comparable to previous determinations. A relation is found between bright regions and down-flows. Large Doppler widths correspond to strong velocity gradients. Title: Mass motions in the solar chromosphere and transition zone Authors: Mein, P.; Simon, G.; Vial, J. C.; Shine, R. A. Bibcode: 1982A&A...111..136M Altcode: A comparison is made between H-alpha and C IV observations of Active Region 2717 on October 9, 1980. On the basis of this comparison, it is found that upward velocities are present above sunspots in the chromosphere-corona transition zone (20 km/s). The downward velocities are found to be well correlated in both lines. Doppler-shift ratios between C IV and H-alpha levels (approximately 10) are seen to be much smaller than expected from density ratio estimates. The comparison is seen as suggesting that flow lines are probably far from vertical in the transition zone. It is pointed out, however, that this depends on model densities that may not be correct. A simple method for comparing matter flows is presented. The best fit between H-alpha and C IV levels is obtained when C IV Doppler shifts are multiplied by the line intensity to the power 0.5 (approximately) in order to make allowance for density fluctuations. Title: Structure and Physics of Solar Faculae - Part Two - the Non-Thermal Velocity Field above Faculae Authors: Mouradian, Z.; Dumont, S.; Pecker, J. -C.; Chipman, E.; Artzner, G. E.; Vial, J. C. Bibcode: 1982SoPh...78...83M Altcode: The OSO-8 satellite enabled us to study various characteristics of the profiles of Si II, Si IV, C IV, and O VI lines above active areas of the Sun, as well as above quiet areas, and to derive some physical properties of the transition region between chromosphere and corona (CCT): (i) The study of the lines shows a general tendency for the microvelocity fields on the average to be nearly constant for the heights corresponding to T > 105 K; however they seem to slightly increase with height in quiet areas, and decrease in active areas. (ii) A multicomponent model of the CCT is however quite necessary, and its geometry is far from being a set of plane-parallel columns. It is similar to an association of moving knots within the non-moving principal component of the matter. (iii) The proportion of mass, in the knots relative to that in the non-moving component, is several times larger in active regions than in quiet regions. (iv) In the knots, the non-thermal microvelocity fields are smaller in active regions and seem to decrease for T increasing above 105 K, contrary to what happens in the steady principal component. Of course, we consider that microturbulence and Doppler shift are two aspects of the same distribution of velocity. Title: Two-dimensional nonlocal thermodynamic equilibrium transfer computations of resonance lines in quiescent prominences Authors: Vial, J. C. Bibcode: 1982ApJ...254..780V Altcode: The two-dimensional transfer code of Mihalas, Auer and Mihalas (1978) is used to compute emergent profiles of resonance lines of H I, Mg II, and Ca II. The model (a uniform slab limited in two directions) and the radiative and thermodynamic quantities are described. The metallic line profiles are sensitive to the ionization degree, which is fixed at a certain value. Some modifications are implemented in the code, in particular, the true incident profiles of chromospheric lines. A comparison is made between two-dimensional and one-dimensional profiles. Good agreement between computed and observed profiles is found for Ly-alpha and Ca II but not for Mg II lines. Title: Optically thick lines in a quiescent prominence - Profiles of Lyman-alpha, Lyman-beta /H I/, K and H /Mg II/, and K and H /Ca II/ lines with the OSO 8 LPSP instrument Authors: Vial, J. C. Bibcode: 1982ApJ...253..330V Altcode: The first set of simultaneous measurements are presented of H I Lyman-alpha and Lyman-beta, Ca II K and H, and Mg II k and h lines in a quiescent prominence. It is found that: (1) Ca II resonance lines have low opacity, with an optical thickness at the center of the K line varying between 1.4 and 3.2, and nonthermal velocities ranging from 5 to 9 km/sec.; (2) the resonance lines of Mg II, as measured in the whole prominence, depart from Gaussian profiles and are unexplainably broader than the corresponding Ca II ones. The observed Mg II and Ca II 'inverted' intensity ratios may be due to different incident intensities ratios; and (3) the Lyman-alpha and Lyman-beta lines of H I have the same reversals as the chromospheric lines in bright regions, and unreversed profiles may be observed in darker regions. The intensities are larger than the diluted incident radiation, and the opacity reaches values of 100,000. Title: Preflare heating of filaments Authors: Malherbe, J. M.; Simon, G.; Mein, P.; Mein, N.; Schmieder, B.; Vial, J. C. Bibcode: 1982AdSpR...2k..53M Altcode: 1982AdSpR...2...53M Disappearances of preflare filaments have been observed on June 22, 1980 (S07,W13) (flare at 13.04 U.T.) and September 3, 1980 (flare at 7.52 U.T.). The analysis of MSDP data (MEUDON) leads to the followings conclusions : - Disappearances begin a few minutes before the Hα impulsive phase. - The filaments can be seen again after the flares. - Upwards motions occur in several points, without disturbing significantly preëxisting downflows.

Velocity maps suggest shears or velocity loops.

The filament disappearance seems to be due to a heating mechanism beginning before the flare maximum. Title: A surge obsrved in Hα and CIV Authors: Schmieder, B.; Mein, P.; Vial, J. C.; Tandberg-Hanssen, E. Bibcode: 1982AdSpR...2k.225S Altcode: 1982AdSpR...2..225S Simultaneous Hα (MSDP at Meudon) and C IV (UVSP aboard SMM) measurements of Active Region 2701 were made on October 2, 1980. Isodensity and velocity maps were derived for both lines and superposed. A good correlation was found between Hα and C IV velocities. A surge was observed for 10 minutes. The base was located in a bright point in CIV and Hα, and escaping matter followed the same channel (``absorbing'' in Hα, ``emitting'' in C IV). The velocity along the surge was about 80 kms.-1 in Hα and 100 km s-1 in C IV. A loop appeared in C IV. We discuss the existing models and conclude that the vertical pressure gradient was capable of driving the surge. Title: Physical properties of the solar chromosphere deduced from optically thick lines. I - Observations, data reduction, and modelling of an average plage Authors: Lemaire, P.; Gouttebroze, P.; Vial, J. C.; Artzner, G. E. Bibcode: 1981A&A...103..160L Altcode: Simultaneous Ca II H and K, Mg II h and k, and H I Lyman-alpha and Lyman-beta profiles have been recorded by the OSO-8/LPSP spectrometer on a quiet sun area and a part of plage, McMath 13738. After data reduction and filtering, a full set of calibrated profiles is obtained. Using a code developed at LPSP (Gouttebroze et al., 1978), profiles computed from VAL III model C (Vernazza et al., 1981) are compared to observations. A specific plage model has been computed to fit the observed profiles. This model reproduces successfully Ca II H and K, and H I Lyman-alpha and Lyman-beta, but partly fails with Mg II h and k. Atmospheric inhomogeneities and dynamical effects may contribute to this discrepancy, and it is proposed that the level number entering in the Mg II computation be increased to take account of a likely fluorescence induced by the H I Lyman-beta radiation field. Title: Absorption feature observed on the H Lyman-alpha solar line - an interpretation Authors: Artzner, G.; Cazes, S.; Emerich, C.; Vial, J. C.; Lemaire, P. Bibcode: 1981A&A...100..205A Altcode: A narrow absorption feature on the red part of the solar H Lyman-alpha profile has been observed by two instruments in 1975 and attributed to atomic hydrogen of the nearby interplanetary gas. This hypothesis implies that the absorption feature shifts with the position of the earth on its orbit. New measurements above active regions at other seasons rule out this hypothesis. On the other hand, appropriate laboratory calibrations indicate that the absorption feature is likely due to a ghost image of the geocoronal absorption. Title: Lα, Lβ (of H i), k and h (of Mg ii), K and H (of Ca ii) observations in a quiescent prominence with the OSO-8 LPSP instrument Authors: Vial, J. C.; Martres, M. J.; Salm-Platzer, J. Bibcode: 1981SoPh...70..325V Altcode: A sequence of images taken at different positions in the resonance lines of Ca II, Mg II, and H I was obtained over a quiescent prominence with the LPSP instrument on OSO-8. Ca II K (and H) profiles are reconstructed at different locations in the prominence with a (10 × 5) arc sec2 resolution. Significant variations of FWHM and line shifts are found: FWHM range from 0.14 Å to 0.5 Å; blue shifts reach about 14 km s-1. The ratio of K to H absolute intensities shows a large spread around the average value of 1.2. The same ratio for the Mg II lines in the whole prominence is higher (1.7), a fact already noticed at the edge of an active prominence (Vial et al., 1979). The ionization degree, as measured by the Lα/Ca K ratio, shows noticeable variations within the prominence. The Lα intensity is about 0.3 times the intensity measured in the quiet Sun, and the Lα/Lβ ratio is less than one half the disk value. These results indicate important variations of the thermal conditions inside the prominence. Title: OSO-8 Observations of CAII H and K MGII H and K Lyman-Alpha and Lyman-Beta above a Sunspot Authors: Kneer, F.; Scharmer, G.; Mattig, W.; Wyller, A.; Artzner, G.; Lemaire, P.; Vial, J. C. Bibcode: 1981SoPh...69..289K Altcode: Observations with the French (L.P.S.P.) experiment on board OSO-8 of a sunspot and nearby plage region are described. The behaviour of the emission cores of the Ca II H and K and Mg II h and k resonance lines is very similar and the correspondence in intensity between the four lines persists in all observed features. In contrast, the Lyman lines show little correlation with the other lines. Their emission regions appear broader in the spectroheliograms than the underlying sunspot structure and must not necessarily possess a counterpart in lower layers. From the central intensity of Lα above the umbra an electron density of 4.3 × 1010 cm-3 ≲ne* ≲2.3 × 1011 cm-3 at 20 000 K is estimated. Title: Solar H I LY alpha far wing measurement Authors: Jouchoux, A.; Vial, J. C.; Artzner, G. E.; Gouttebroze, P.; Lemaire, P. Bibcode: 1981A&A....93..415J Altcode: High spectral resolution photoelectric observations of the solar H I Ly alpha far wing are presented. Measurements above active regions and quiet sun center are compared to photographic observations of Basri et al. (1979). Title: Contribution à l'étude des protubérances solaires à partir des observations effectuées sur l'instrument du LPSP à bord du satellite OSO-8 Title: Contribution à l'étude des protubérances solaires à partir des observations effectuées sur l'instrument du LPSP à bord du satellite OSO-8 Title: Contribution to the study of solar prominences from observations made on the LPSP instrument on board the OSO-8 satellite; Authors: Vial, Jean-Claude Jacques Bibcode: 1981PhDT........42V Altcode: No abstract at ADS Title: On VI (λ = 1032 Å) profiles in and above an active region prominence, compared to quiet Sun center and limb profiles Authors: Vial, J. C.; Lemaire, P.; Artzner, G.; Gouttebroze, P. Bibcode: 1980SoPh...68..187V Altcode: O VI (λ = 1032 Å) profiles have been measured in and above a filament at the limb, previously analyzed in H I, Mg II, Ca II resonance lines (Vial et al., 1979). They are compared to profiles measured at the quiet Sun center and at the quiet Sun limb. Title: Microturbulence near the edge of a solar plage Authors: Simon, G.; Mouradian, Z.; Dumont, S.; Pecker, J. C.; Artzner, G.; Vial, J. C. Bibcode: 1980A&A....89L...8S Altcode: Observations of the Ca II K line at the edge of a solar plage show enhanced separation of the K2 peaks with respect to the measured value inside the plage and in the quiet sun. This effect may be interpreted as a variation of microturbulent motions at the height of formation of K2. Title: Observations of Chromospheric Lines from OSO-8 Authors: Grossmann-Doerth, U.; Kneer, F.; Uexkuell, M.; Artzner, G. E.; Vial, J. C. Bibcode: 1980SoPh...66....3G Altcode: The line profiles of Lα, Ca II K and Mg IIk were measured with the spectrometer of the `Laboratoire de Physique Stellaire et Planétaire' on board of OSO-8. The results of these measurements are presented. Title: Center-to-limb solar observations of the K2 component of the Ca II K line with the OSO 8 satellite. Authors: Dumont, S.; Mouradian, Z.; Pecker, J. -C.; Simon, G.; Artzner, G. E.; Vial, J. C. Bibcode: 1980CRASB.290..365D Altcode: OSO 8 spectrometer measurements of the separation between emission peaks in the K2 Ca II line across the solar disk in quiet and active regions are presented. The center-to-limb variation in emission peak separation is found to differ slightly for quiet and facula regions at distances greater than 0.2 solar radii from the limb, in agreement with previous observations. For a facula located at the solar limb, however, the peak separation is observed to be up to 35 percent greater than in quiet regions, indicating the presence of a region of enhanced chromospheric turbulence surrounding the faculae. Title: Non thermal velocities in the chromosphere-corona transition zone of solar active regions. Authors: Dumont, S.; Mouradian, Z.; Pecker, J. -C.; Chipman, E.; Artzner, G.; Vial, J. -C. Bibcode: 1980CRASB.290..317D Altcode: OSO 8 satellite observations of lines of the Si II, Si IV, C IV and O VI ions in the ultraviolet spectrum of active solar regions are considered. It is noted that for the case of pronounced physical dispersion of the data, there is no marked systematic variation from the center to the edge of the solar disk. The nonthermal velocities in the transition zone are, for a given temperature, the same as for quiet regions. In addition, the velocities tend to reach a constant value at temperatures above 100,000 deg K, and the observed physical dispersion is much higher than the inaccuracy of the data. Title: Profiles of H I (Lalpha ), Mg II (h and k), Ca II (H and K) lines of an active filament at the limb, with the LPSP instrument aboard the OSO-8 satellite. Authors: Vial, J. C.; Gouttebroze, P.; Artzner, G.; Lemaire, P. Bibcode: 1979SoPh...61...39V Altcode: We scanned the H I Lα, Mg II h and k, Ca II K and H lines simultaneously with the LPSP instrument on OSO-8, to investigate the low and moderate temperature regions of an `active region filament'. The Lα line is not reversed except for the innermost position in the prominence. Intensity (k/h), (K/H) ratios are respectively 2 and 1.1, indicating that the Mg II lines are optically thin, and that Ca II K is saturated, although not clearly reversed. The results obtained during the second sequence of observations (K saturated before Lα for example) indicate that within the size of the slit (1″ × 10″) we are not observing the same emitting features in the different lines. Title: LY α and β of hi, H and K of MG ii, H and K of CA II Profiles of a Quiescent Prominence Obtained with the LPSP Instrument of OSO-8. Authors: Vial, J. C.; Lemaire, P.; Gouttebroze, P. Bibcode: 1979phsp.coll...52V Altcode: 1979IAUCo..44...52V No abstract at ADS Title: Profiles of H i (Lyα), MG II (h and K), CA II (h and k) Lines in an Active Filament at the Limb, Observed with the LPSP Instrument Onboard the OSO-8 Satellite. Authors: Vial, J. C.; Gouttebroze, P.; Artzner, G.; Lemaire, P. Bibcode: 1979phsp.coll..250V Altcode: 1979IAUCo..44..250V No abstract at ADS Title: The solar hydrogen Lyman-beta and Lyman-alpha lines: disk center observations from OSO 8 compared with theoretical profiles. Authors: Gouttebroze, P.; Lemaire, P.; Vial, J. C.; Artzner, G. Bibcode: 1978ApJ...225..655G Altcode: The solar La and Lfl lines of hydrogen have been measured at the center of the disk with the LPSP spectrometer aboard OSO 8. These line profiles are compared with theoretical profiles obtained with different solar atmospheric models, assuming either complete or partial frequency redistribution in scattering. The assumption of microturbulence for the velocity fields appears insufficient to account for the profiles of the line cores; better results are obtained with a blend of micro- and macroturbulence, which shows the need of a generalized treatment of the turbulent motions in the formation of these lines. If the effects of partial redistribution are taken into account, a good fit of the line wings requires higher temperatures, in the region under the plateau, than in the reference atmospheric model of Vernazza, Avrett, and Loeser. Subject headings: line formation - line profiles - Sun: chromosphere - Sun: spectra - ultraviolet: spectra Title: Simultaneous time-resolved observations of the H Lalpha , Mg k 2795 Å, and Ca K solar lines. Authors: Artzner, G.; Leibacher, J.; Vial, J. C.; Lemaire, P.; Gouttebroze, P. Bibcode: 1978ApJ...224L..83A Altcode: No abstract at ADS Title: Calibrated full disk solar H I Lyman-alpha and Lyman-beta profiles. Authors: Lemaire, P.; Charra, J.; Jouchoux, A.; Vidal-Madjar, A.; Artzner, G. E.; Vial, J. C.; Bonnet, R. M.; Skumanich, A. Bibcode: 1978ApJ...223L..55L Altcode: Resolved solar H I Ly-alpha and -beta profiles have been recorded by the French LPSP experiment on OSO 8. Intensity observations at the center and the limb have been combined to obtain flux-equivalent profiles (5.46 plus or minus 30 percent and 0.078 plus or minus 25 percent erg/sq cm per sec for Ly-alpha and -beta, respectively). Comparison of the flux profiles with unresolved calibration rocket profiles allows one to obtain an absolute calibration. Title: The LPSP instrument on OSO 8. II. In-flight performance and preliminary results. Authors: Bonnet, R. M.; Lemaire, P.; Vial, J. C.; Artzner, G.; Gouttebroze, P.; Jouchoux, A.; Leibacher, J. W.; Skumanich, A.; Vidal-Madjar, A. Bibcode: 1978ApJ...221.1032B Altcode: The paper describes the in-flight performance for the first 18 months of operation of the LPSP (Laboratoire de Physique Stellaire et Planetaire) instrument incorporated in the OSO 8 launched June 1975. By means of the instrument, an absolute pointing accuracy of nearly one second was achieved in orbit during real-time operations. The instrument uses a Cassegrain telescope and a spectrometer simultaneously observing six wavelengths. In-flight performance is discussed with attention to angular resolution, spectral resolution, dispersion and grating mechanism (spectral scanner) stability, scattered light background and dark current, photometric standardization, and absolute calibration. Real-time operation and problems are considered with reference to pointing system problems, target acquisition, and L-alpha modulation. Preliminary results involving the observational program, quiet sun and chromospheric studies, quiet chromospheric oscillation and transients, sunspots and active regions, prominences, and aeronomy investigations are reported. Title: Doppler Shifts measured in 0 VI line from OSO-B observations above and in the vicinity of plage Mc Math 13738. Authors: Lemaire, P.; Skumanich, A.; Artzner, G.; Gouttebroze, P.; Vial, J. C.; Bonnet, R. M.; McWhirter, P. Bibcode: 1978BAAS...10Q.440L Altcode: No abstract at ADS Title: OSO-8 Radio and X-ray observations of the 19 April 1977 flare. Authors: Skumanich, A.; Jouchoux, A.; Castelli, J.; Lemaire, P.; Artzner, G.; Gouttebroze, P.; Vial, J. C.; Bonnet, R. M. Bibcode: 1978BAAS...10..441S Altcode: No abstract at ADS Title: EUV observations of class-C X-ray flare by the LPSP (Laboratoire de Physique Stellaire et Planétaire du Centre National de la Recherche Scientifique) spectrometer on OSO-8. Authors: Jouchoux, A.; Skumanich, A.; Bonnet, R. M.; Lemaire, P.; Artzner, G.; Leibacher, J.; Vial, J. C.; Vidal-Madjar, A. Bibcode: 1977BAAS....9..432J Altcode: No abstract at ADS Title: The LPSP experiment on OSO-8. I - Instrumentation, description of operations, laboratory calibrations and pre-launch performances Authors: Artzner, G.; Bonnet, R. M.; Vial, J. C.; Jouchoux, A.; Leibacher, J.; Vidal-Madjar, A.; Lemaire, P. Bibcode: 1977SSI.....3..131A Altcode: The characteristics of OSO-8, including its solar-pointed instrument assembly and rasters, are discussed, as well as the accompanying Laboratoire de Physique Stellaire et Planetaire (LPSP) instrumentation, which is designed to study the solar atmosphere with high spatial, spectral, and temporal resolution. The LPSP instrument, which consists of two subassemblies, a Cassegrainian telescope and a spectrometer, is described; main optical characteristics, including spectral lines observed, and means of correcting aberrations and eliminating stray light, are given for the spectrometer. Detectors and their capacities, and various filter wheel configurations available for detection of polarized light and discrimination of low orders of diffraction, are also described. The observation program, which consists of a study of solar prominences, flares, and dynamic and three-dimensional physical structures of the chromosphere, as well as determination of seasonal variations of some gases in earth's atmosphere, is reviewed. A detailed account of pre-launch tests and calibration procedures is also given. Title: Extreme-Ultraviolet Observations of New Cycle Sunspots with the LPSP Spectrometer from OSO-8 Authors: Skumanich, A.; Jouchoux, A.; Artzner, G.; Bonnet, R. M.; Leibacher, J.; Lemaire, P.; Vial, J. C.; Vidal-Madjar, A. Bibcode: 1977BAAS....9..340S Altcode: No abstract at ADS Title: On VI Profiles of Solar Quiet and Active Areas Recorded by OSO-8 LPSP Experiment". Authors: Lemaire, P.; Artzner, G.; Vial, J. C.; Bonnet, R. M.; Gottebroze, P.; Jouchoux, A.; Vidal-Madjar, A.; McWhirter, P.; Leibacher, J.; Skumainich, A. Bibcode: 1977uxsa.coll...46L Altcode: 1977IAUCo..43...46L No abstract at ADS Title: OSO-8 Observations of the EUV Chromospheric Network Authors: Artzner, G.; Bonnet, R. M.; Leibacher, J.; Lemaire, P.; Skumanich, A.; Vial, J. C.; Vidal-Madjar, A. Bibcode: 1976BAAS....8..332A Altcode: No abstract at ADS Title: Evolution of sunspot and active region morphology as observed on the resonance lines of Ca+ (K, H), Mg+ (k, h), hydrogen (Lalpha , Lbeta ), and O VI from OSO-8 (LPSP). Authors: Artzner, G.; Skumanich, A.; Bonnet, R. M.; Vidal-Madjar, A.; Leibacher, J.; Lemaire, P.; Vial, J. C. Bibcode: 1976BAAS....8..397A Altcode: No abstract at ADS Title: Periodic temporal phenomena in the solar chromosphere as observed from OSO-8 (LPSP). Authors: Vial, J. C.; Leibacher, J.; Lemaire, P.; Artzner, G.; Bonnet, R. M.; Skumanich, A.; Vidal-Madjar, A. Bibcode: 1976BAAS....8..397V Altcode: No abstract at ADS Title: Spatial variations of solar profiles of Ca+ H and K, Mg+ h and k, and Lyman alpha and beta (H I) resonance lines as observed from OSO-8 (LPSP). Authors: Bonnet, R. M.; Artzner, G.; Leibacher, J.; Lemaire, P.; Skumanich, A.; Vial, J. C.; Vidal-Madjar, A. Bibcode: 1976BAAS....8..397B Altcode: No abstract at ADS Title: Prominence Observations with the OSO-8 French Experiment Authors: Vial, J. C.; Artzner, G.; Bonnet, R. M.; Lemaire, P.; Leibacher, J.; Skumanich, A.; Vidalmadjar, A. Bibcode: 1976BAAS....8..344V Altcode: No abstract at ADS Title: High-Resolution Atmospheric Extinction Measurements from the French Experiment on Board the NASA Spacecraft OSO-8 Authors: Vidal-Madjar, A.; Roble, R. G.; Mankin, W. G.; Artzner, G.; Bonnet, R. M.; Lemaire, P.; Vial, J. C. Bibcode: 1976ASSL...61..117V Altcode: 1976aps..conf..117V No abstract at ADS Title: High resolution atmospheric extinction measurements from the French experiment on board the NASA spacecraft OSO-8 Authors: Vidal-Madjar, A.; Artzner, G.; Bonnet, R. M.; Lemaire, P.; Vial, J. C.; Roble, R. G.; Mankin, W. G. Bibcode: 1976atps.proc..117V Altcode: The French instrument aboard OSO-8 is a multichannel, high-resolution UV spectrometer for observing very small areas of the sun simultaneously in the Ca II, Mg II, Lyman alpha, and Lyman beta lines. By observing extinction through the earth atmosphere, the spectrometer studies the three-dimensional structure and the composition of the atmosphere. The quality of data appears to give a 500 m vertical resolution both for O3 and O2; O3 is observed primarily from 55 to 75 km, while O2 is observed from 85 to 200 km. Data on the hydrogen absorption present a new method for evaluating exospheric temperature and atomic hydrogen density at each point of the exobase. Title: Angular Dependence of the Optical Properties of a Narrow Band Interference Filter Authors: Koutoumy, S.; Vial, J. -C. Bibcode: 1973A&A....25..145K Altcode: Summary. An interferential filter, 2" diameter, centered around Hoc line, has been studied. Its resolving power with unpolarized light, is 0/ 4. 1O . The instrumental width of the spectrometer was less than 0.3 A and the field less than 10'. Wavelength shift A and half height bandwidth variation of the I.F. are given for different incident angles 0. The beam was almost plane parallel; natural and linear polarized light were used. The wavelength splitting was not observed up to A 10(a ). Polarization effects due to the filter are important and we empirically deduced the following formula: II- 1 (0.0610.01)00(A) for 0 less than 5 . Key words: Hoc interference filter - polarization - spectral transmission - instrumental technique Title: Intensity Distribution in the LYMAN-α Line at the Solar Limb Authors: Vial, J. C. Bibcode: 1970IAUS...36..260V Altcode: No abstract at ADS