Author name code: berlicki ADS astronomy entries on 2022-09-14 author:"Berlicki, Arkadiusz" OR author:"Berlicki, Arek" ------------------------------------------------------------------------ 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: A first comparison of FLARIX flare simulations with the MSDP H-alpha spectral observations on very short time scales Authors: Heinzel, Petr; Kasparova, Jana; Berlicki, Arkadiusz; Radziszewski, Krzysztof; Rudawy, Pawel Bibcode: 2022cosp...44.2560H Altcode: We present first results of a comparative analysis of high temporal resolution MSDP H$\alpha$ observations of a compact solar flare with results of radiation-hydrodynamical simulations performed using the FLARIX code. X-ray spectral observations of a compact C1 GOES-class flare obtained from RHESSI satellite were used to estimate physical parameters of the electron beams transporting the energy from the reconnection site down to the chromosphere. These parameters are then used for data-driven FLARIX simulations. A small size of the flare and its simple structure allowed us to assume a single-loop geometry which significantly simplified the modelling and analysis of the whole event. Using the MSDP imaging spectrograph at Bia{\l}k\'{o}w observatory, it was possible to compare the recorded H$\alpha$ line emission with that obtained from FLARIX simulations, on short time-scales down to 50 ms. Title: Geometry and dynamics of cool flare loops observed by IRIS Authors: Mikuła, Katarzyna; Heinzel, Petr; Berlicki, Arkadiusz Bibcode: 2022cosp...44.2414M Altcode: Flare loops represent a well-known, inseparable part of solar flares. They are observed mainly during the gradual phase of the flares, being rooted in flare ribbons. They can form an entire arcade which evolves in the corona, sometimes for hours. The loops are visible in a wide range of temperature bands, from X-rays (hot flare loops) to temperatures of the cool chromospheric-type plasma seen in the ultraviolet and optical spectrum (cool flare loops). We present results of our analysis of cool flare loops observed during the gradual phase of M6.5 solar flare on June 22, 2015 based on the ultraviolet observations obtained by Interface Region Imaging Spectrograph (IRIS). Detailed investigation of these loops, made on the basis of Mg II line profiles, was presented in Mikuła et al. (2017). Mg II line profiles were modelled using the standard cloud model method that allowed us obtaining simultaneously the physical parameters characteridsing the moving plasma inside selected loops, i.e. the velocity along the line-of-sight, microturbulent velocity, optical thickness, and the line source function. Here we present a next step of the work — reconstruction of the true shape of flare loops based on the geometric method of Loughhead, Wang and Blows (1983). Based on two-dimensional images of a given loop structure located on the solar disk or at the limb, we can obtain its true orientation and its size. The shape of the analysed loops was determined mainly from IRIS slit-jaw images at 1330, 1400 and 2796 \AA{}, supplemented with SDO/AIA 171 \AA{} images in some cases. Using basic geometry, we reconstructed the shape of selected loops in the three-dimensional space. Based on the method presented in Loughhead and Bray (1984) we were able to derive the so-called true velocity of the plasma flows, i.e. the velocity along the loop axis. The results obtained for each loop were then compared with the free fall velocities. Title: New Insight into UV Compact Bursts - Statistical Analysis of IRIS Data Authors: Berlicki, Arkadiusz; Heinzel, Petr; Schmieder, Brigitte; Michalina Litwicka, M. Bibcode: 2022cosp...44.2532B Altcode: UV small-scale brightenings have been frequently observed by IRIS in both NUV and FUV channels. They appear as compact and intense, but short lived bursts visible within the solar active regions. Some of them seem to be closely connected with the well-known Ellerman bombs and so-called IRIS bombs. Based on the IRIS observations of many compact bursts obtained in chromospheric Mg II h and k lines, Mg II triplet and FUV lines we present detailed statistical analysis of these phenomena. In the work of Grubecka et al. (2016), five different compact bursts (CBs) were selected and analysed in detail. NLTE semi-empirical models of them were constructed based on their spectral characteristics in the Mg II h and k lines. In addition, they were preliminarily categorised into three types. In present work we extend previous analysis and investigate statistical diversity of Mg II lines of UV bursts and their visibility in FUV lines such as Si IV or C II. IRIS database from 2013-2018 was searched for dense rasters of active and emerging flux regions containing spectra in Mg II, C II and Si IV. A next step was to reconstruct full rasters in which we were looking for compact brightenings with size of the order of one arcsec. We found more than two thousands CBs using criteria based on specific parameters of the Mg II k line profile. In addition, we analysed also the emission of Mg II UV triplet and some parameters of Si IV and C II lines. This database allowed us to make a novel statistical analysis of all bursts and we categorised them in previously defined three types, depending on their Mg II line profiles shapes. We also investigated the correlations between the emission of Mg II lines, "hotter" Si IV lines, and C II lines in order to find which of these events are linked with IRIS bombs (Peter et al. 2014). Finally, we analysed some observables of those UV bursts, which can be defined as candidates for Ellerman bombs. Title: Diagnostics of The Prominence Plasma Based on IRIS, H-alpha and ALMA Observations Authors: Berlicki, Arkadiusz; Bárta, Miroslav; Gunár, Stanislav; Heinzel, Petr; Jejcic, Sonja; Radziszewski, Krzysztof; Rudawy, Pawel Bibcode: 2022cosp...44.2543B Altcode: Solar prominences are now commonly observed above the solar limb in different spectral bands and recent developments of new observing techniques allow us to detect them from radio to far-UV ranges. In addition to often used spectral observations in optical and UV, ALMA interferometer obtained high-resolution images of a quiescent solar prominence at 3 millimeters (Band 3) during the coordinated space and ground-based observing campaign. For the first time high-resolution observations of such structures in the millimeter radio domain are available. The fine structures of this prominence was also observed in the UV with IRIS and in the H$\alpha$ line with the MSDP of Wroc{\l}aw Observatory. Both UV and H$\alpha$ data contains not only images, but also spectra which makes the available dataset extremely valuable. Moreover, all UV, H$\alpha$ and ALMA observations are co-temporal which gives an unprecedented opportunity for a novel diagnostic, not available so far. In this work we present analysis of the prominence spectral characteristics in H$\alpha$ and UV Mg II lines, looking for the statistical dependence between different parameters (metrics) in the line profiles. This combined data is then used for determination of plasma parameters in the prominence fine structures. In addition, UV and H$\alpha$ spectral maps are compared with the brightness temperature mosaics from ALMA, providing an additional constraint on the plasma kinetic temperature. Detailed diagnostics is then based on extensive NLTE numerical simulations of the radiative transfer inside heterogeneous prominence structures. Title: ALMA as a Prominence Thermometer: First Observations Authors: Heinzel, Petr; Berlicki, Arkadiusz; Bárta, Miroslav; Rudawy, Paweł; Gunár, Stanislav; Labrosse, Nicolas; Radziszewski, Krzysztof Bibcode: 2022ApJ...927L..29H Altcode: 2022arXiv220212761H We present first prominence observations obtained with Atacama Large Millimeter Array (ALMA) in Band 3 at the wavelength of 3 mm. High-resolution observations have been coaligned with the MSDP Hα data from Wrocław-Białków large coronagraph at similar spatial resolution. We analyze one particular cotemporal snapshot, first calibrating both ALMA and MSDP data and then demonstrating a reasonable correlation between both. In particular, we can see quite similar fine-structure patterns in both ALMA brightness-temperature maps and MSDP maps of Hα intensities. Using ALMA, we intend to derive the prominence kinetic temperatures. However, having current observations only in one band, we use an independent diagnostic constraint, which is the Hα line integrated intensity. We develop an inversion code and show that it can provide realistic temperatures for brighter parts of the prominence where one gets a unique solution, while within faint structures, such inversion is ill conditioned. In brighter parts, ALMA serves as a prominence thermometer, provided that the optical thickness in Band 3 is large enough. In order to find a relation between brightness and kinetic temperatures for a given observed Hα intensity, we constructed an extended grid of non-LTE prominence models covering a broad range of prominence parameters. We also show the effect of the plane-of-sky filling factor on our 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: Metis - Solar Orbiter Topical Team on "Modelling of CME propagation/evolution in corona and solar wind in connection with Space Weather" Authors: Bemporad, A.; Banerjee, D.; Berlicki, A.; Biondo, R.; Boe, B.; Calchetti, D.; Capuano, G.; De Leo, Y.; Del Moro, D.; Feng, L.; Foldes, R.; Frassati, F.; Frazin, R. A.; Giovannelli, L.; Giunta, A. S.; Heinzel, P.; Ippolito, A.; Janvier, M.; Jerse, G.; Kilpua, K. E. J.; Laurenza, M.; Lloveras, D.; Magdalenic, J.; Mancuso, S.; Messerotti, M.; Mierla, M.; Nandy, D.; Napoletano, G.; Nuevo, F.; Pagano, P.; Pinto, R.; Plainaki, C.; Reale, F.; Romoli, M.; Rodriguez, L.; Slemer, A.; Spadaro, D.; Susino, R.; Stangalini, M.; Vainio, R. O.; Valori, G.; Vásquez, A. M.; West, M. J. Bibcode: 2020AGUFMSH0360027B Altcode: Despite the current availability of multi-spacecraft observations of Coronal Mass Ejections (CMEs) and their interplanetary counterpart (ICMEs), at present we still don't understand which physical phenomena are driving their expansion and propagation phases. This also limits our understanding on how CMEs (observed with remote sensing data) become ICMEs (observed in situ), how they interact with the background solar wind, and how their final geo-effectiveness can be modified during their interplanetary evolution. Such problems match some of the scientific objectives of the Solar Orbiter Science Activity Plan and of the Metis coronagraph. Thanks to its multi-channel capability, Metis (acquiring images in the visible light and at the same time in the UV HI Lyman-alpha emission) will really provide an unprecedented view of CMEs and in particular of their thermodynamic evolution. At closest approaches to the Sun (in the nominal mission), Metis will acquire high spatial resolution and/or temporal cadence multi-channel images of CMEs. Farther from the Sun, Metis will shed light on the early Interplanetary propagation of CMEs. Later on (in the extended mission) Metis will observe for the first time the CME/ICME propagation out-of-ecliptic. These novelties will be combined with the unique vantage point that will be offered by the Solar Orbiter spacecraft, and supported with valuable data acquired by other on-board remote sensing (e.g. SPICE, EUI, SoloHI) and in situ (e.g. EPD, MAG, SWA, RPW) instruments. In this contribution we present the ongoing activities of the Metis Topical Team on "CME/ICME propagation", (http://metis.oato.inaf.it/topical_teams.html), an international working group recently established and gathering scientists from different countries, experts of both in-situ and remote sensing observations, as well as numerical simulations, and we summarize the main science objectives discussed during the last months. 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: Optical design of the multi-wavelength imaging coronagraph Metis for the solar orbiter mission Authors: Fineschi, S.; Naletto, G.; Romoli, M.; Da Deppo, V.; Antonucci, E.; Moses, D.; Malvezzi, A. M.; Nicolini, G.; Spadaro, D.; Teriaca, L.; Andretta, V.; Capobianco, G.; Crescenzio, G.; Focardi, M.; Frassetto, F.; Landini, F.; Massone, G.; Melich, R.; Nicolosi, P.; Pancrazzi, M.; Pelizzo, M. G.; Poletto, L.; Schühle, U.; Uslenghi, M.; Vives, S.; Solanki, S. K.; Heinzel, P.; Berlicki, A.; Cesare, S.; Morea, D.; Mottini, S.; Sandri, P.; Alvarez-Herrero, A.; Castronuovo, M. Bibcode: 2020ExA....49..239F Altcode: 2020ExA...tmp...14F This paper describes the innovative optical design of the Metis coronagraph for the Solar Orbiter ESA-NASA mission. Metis is a multi-wavelength, externally occulted telescope for the imaging of the solar corona in both the visible and ultraviolet wavelength ranges. Metis adopts a novel occultation scheme for the solar disk, that we named "inverse external occulter", for reducing the extremely high thermal load on the instrument at the spacecraft perihelion. The core of the Metis optical design is an aplanatic Gregorian telescope common to both the visible and ultraviolet channels. A suitable dichroic beam-splitter, optimized for transmitting a narrow-band in the ultraviolet (121.6 nm, HI Lyman-α) and reflecting a broadband in the visible (580-640 nm) spectral range, is used to separate the two optical paths. Along the visible light optical path, a liquid crystal electro-optical modulator, used for the first time in space, allows making polarimetric measurements. Title: A Search for High-Frequency Coronal Brightness Variations in the 21 August 2017 Total Solar Eclipse Authors: Rudawy, P.; Radziszewski, K.; Berlicki, A.; Phillips, K. J. H.; Jess, D. B.; Keys, P. H.; Keenan, F. P. Bibcode: 2019SoPh..294...48R Altcode: 2019arXiv190306076R We report on a search for short-period intensity variations in the green-line (Fe XIV 530.3 nm) emission from the solar corona during the 21 August 2017 total eclipse viewed from Idaho in the United States. Our experiment was performed with a much more sensitive detection system, and with better spatial resolution, than on previous occasions (1999 and 2001 eclipses), allowing fine details of quiet coronal loops and an active-region loop system to be seen. A guided 200-mm-aperture Schmidt-Cassegrain telescope was used with a state-of-the-art CCD camera having 16-bit intensity discrimination and a field-of-view (0.43∘×0.43∘) that encompassed approximately one third of the visible corona. The camera pixel size was 1.55 arcseconds, while the seeing during the eclipse enabled features of ≈2 arcseconds (1450 km on the Sun) to be resolved. A total of 429 images were recorded during a 122.9 second portion of the totality at a frame rate of 3.49 s−1. In the analysis, we searched particularly for short-period intensity oscillations and travelling waves, since theory predicts fast-mode magneto-hydrodynamic (MHD) waves with short periods may be important in quiet coronal and active-region heating. Allowing first for various instrumental and photometric effects, we used a wavelet technique to search for periodicities in some 404 ,000 pixels in the frequency range 0.5 -1.6 Hz (periods 2 seconds to 0.6 seconds). We also searched for travelling waves along some 65 coronal structures. However, we found no statistically significant evidence in either. This negative result considerably refines the limit that we obtained from our previous analyses, and it indicates that future searches for short-period coronal waves may be better directed towards Doppler shifts as well as intensity oscillations. Title: Solar Ultraviolet Bursts Authors: Young, Peter R.; Tian, Hui; Peter, Hardi; Rutten, Robert J.; Nelson, Chris J.; Huang, Zhenghua; Schmieder, Brigitte; Vissers, Gregal J. M.; Toriumi, Shin; Rouppe van der Voort, Luc H. M.; Madjarska, Maria S.; Danilovic, Sanja; Berlicki, Arkadiusz; Chitta, L. P.; Cheung, Mark C. M.; Madsen, Chad; Reardon, Kevin P.; Katsukawa, Yukio; Heinzel, Petr Bibcode: 2018SSRv..214..120Y Altcode: 2018arXiv180505850Y The term "ultraviolet (UV) burst" is introduced to describe small, intense, transient brightenings in ultraviolet images of solar active regions. We inventorize their properties and provide a definition based on image sequences in transition-region lines. Coronal signatures are rare, and most bursts are associated with small-scale, canceling opposite-polarity fields in the photosphere that occur in emerging flux regions, moving magnetic features in sunspot moats, and sunspot light bridges. We also compare UV bursts with similar transition-region phenomena found previously in solar ultraviolet spectrometry and with similar phenomena at optical wavelengths, in particular Ellerman bombs. Akin to the latter, UV bursts are probably small-scale magnetic reconnection events occurring in the low atmosphere, at photospheric and/or chromospheric heights. Their intense emission in lines with optically thin formation gives unique diagnostic opportunities for studying the physics of magnetic reconnection in the low solar atmosphere. This paper is a review report from an International Space Science Institute team that met in 2016-2017. Title: IRIS Observations and Modeling of MGII Flare Loops Authors: Heinzel, Petr; Berlicki, Arkadiusz; Mikula, Katarzyna; Liu, Wenjuan Bibcode: 2018cosp...42E1423H Altcode: Solar chromospheric flares are often associated with cool loops which are rooted in the ribbons. These loops extend into coronal altitudes and usually are modelled as prominence-like structures illuminated from the solar disk. The loops exhibit large down-flows (coronal rain) and they evolve in time in accordance with the characteristic cooling times of the loop plasmas. Cool loops are visible in various spectral lines formed at chromospheric temperatures. We exploit novel observations of such loops in MgII h and k lines obtained by the IRIS satellite, analyse selected observations where the cool loops are well visible and studytheir temporal evolution. Our spectroscopic diagnostics is based on 2D non-LTE modelling ofMgII lines in flare loops taking into account the flows along the loops. From these models wedetermine various plasma parameters and the rates of radiation cooling. These results allow usto better understand the structure, dynamics and evolution of cool flare loops. Title: Chromospheric Response during the Precursor and the Main Phase of a B6.4 Flare on 2005 August 20 Authors: Awasthi, Arun Kumar; Rudawy, Pawel; Falewicz, Robert; Berlicki, Arkadiusz; Liu, Rui Bibcode: 2018ApJ...858...98A Altcode: 2018arXiv180402632A Solar flare precursors depict a constrained rate of energy release, in contrast to the imminent rapid energy release, which calls for a different regime of plasma processes to be at play. Due to the subtle emission during the precursor phase, its diagnostics remain delusive, revealing either nonthermal electrons (NTEs) or thermal conduction to be the driver. In this regard, we investigate the chromospheric response during various phases of a B6.4 flare on 2005 August 20. Spatiotemporal investigation of flare ribbon enhancement during the precursor phase, carried out using spectra images recorded in several wavelength positions on the Hα line profile, revealed its delayed response (180 s) compared to the X-ray emission, as well as a sequential increment in the width of the line profile, which are indicative of a slow heating process. However, the energy contained in the Hα emission during the precursor phase can reach as high as 80% of that estimated during the main phase. Additionally, the plasma hydrodynamics during the precursor phase, resulting from the application of a single-loop one-dimensional model, revealed the presence of a power-law extension in the model-generated X-ray spectra, with a flux lower than the RHESSI background. Therefore, our multiwavelength diagnostics and hydrodynamical modeling of the precursor emission indicates the role of a two-stage process. First, reconnection-triggered NTEs, although too small in flux to overcome the observational constraints, thermalize in the upper chromosphere. This leads to the generation of a slow conduction front, which causes plasma heating during the precursor phase. Title: METIS: the visible and UV coronagraph for solar orbiter Authors: Romoli, M.; Landini, F.; Antonucci, E.; Andretta, V.; Berlicki, A.; Fineschi, S.; Moses, J. D.; Naletto, G.; Nicolosi, P.; Nicolini, G.; Spadaro, D.; Teriaca, L.; Baccani, C.; Focardi, M.; Pancrazzi, M.; Pucci, S.; Abbo, L.; Bemporad, A.; Capobianco, G.; Massone, G.; Telloni, D.; Magli, E.; Da Deppo, V.; Frassetto, F.; Pelizzo, M. G.; Poletto, L.; Uslenghi, M.; Vives, S.; Malvezzi, M. Bibcode: 2017SPIE10563E..1MR Altcode: METIS coronagraph is designed to observe the solar corona with an annular field of view from 1.5 to 2.9 degrees in the visible broadband (580-640 nm) and in the UV HI Lyman-alpha, during the Sun close approaching and high latitude tilting orbit of Solar Orbiter. The big challenge for a coronagraph is the stray light rejection. In this paper after a description of the present METIS optical design, the stray light rejection design is presented in detail together with METIS off-pointing strategies throughout the mission. Data shown in this paper derive from the optimization of the optical design performed with Zemax ray tracing and from laboratory breadboards of the occultation system and of the polarimeter. Title: Time Variations of Observed Hα Line Profiles and Precipitation Depths of Nonthermal Electrons in a Solar Flare Authors: Falewicz, Robert; Radziszewski, Krzysztof; Rudawy, Paweł; Berlicki, Arkadiusz Bibcode: 2017ApJ...847...84F Altcode: 2017arXiv170809797F We compare time variations of the Hα and X-ray emissions observed during the pre-impulsive and impulsive phases of the C1.1-class solar flare on 2013 June 21 with those of plasma parameters and synthesized X-ray emission from a 1D hydrodynamic numerical model of the flare. The numerical model was calculated assuming that the external energy is delivered to the flaring loop by nonthermal electrons (NTEs). The Hα spectra and images were obtained using the Multi-channel Subtractive Double Pass spectrograph with a time resolution of 50 ms. The X-ray fluxes and spectra were recorded by RHESSI. Pre-flare geometric and thermodynamic parameters of the model and the delivered energy were estimated using RHESSI data. The time variations of the X-ray light curves in various energy bands and those of the Hα intensities and line profiles were well correlated. The timescales of the observed variations agree with the calculated variations of the plasma parameters in the flaring loop footpoints, reflecting the time variations of the vertical extent of the energy deposition layer. Our result shows that the fast time variations of the Hα emission of the flaring kernels can be explained by momentary changes of the deposited energy flux and the variations of the penetration depths of the NTEs. Title: Optical measurements of the mirrors and of the interferential filter of the Metis coronagraph on Solar Orbiter Authors: Sandri, P.; Sarra, P.; Radaelli, P.; Morea, D.; Melich, R.; Berlicki, A.; Antonucci, E.; Castronuovo, M. M.; Fineschi, S.; Naletto, G.; Nicolini, G.; Romoli, M. Bibcode: 2017SPIE10397E..16S Altcode: The paper describes the wavefront error measurements of the concave ellipsoidal mirrors M1 and M2, of the concave spherical mirror M0 and of the flat interferential filter IF of the Metis coronagraph. Metis is an inverted occultation coronagraph on board of the ESA Solar Orbiter mission providing a broad-band imaging of the full corona in linearly polarized visible-light (580 - 640 nm) and a narrow-band imaging of the full corona in the ultraviolet Lyman α (121.6 nm). Metis will observe the solar outer atmosphere from a close distance to the Sun as 0.28 A.U. and from up to 35deg out-of-ecliptic. The measurements of wavefront error of the mirrors and of the interferential filter of Metis have been performed in a ISO5 clean room both at component level and at assembly level minimizing, during the integration, the stress introduced by the mechanical hardware. The wavefront error measurements have been performed with a digital interferometer for mirrors M0, M1 and M2 and with a Shack-Hartmann wavefront sensor for the interferential filter. Title: Structure and Dynamics of Cool Flare Loops Observed by the Interface Region Imaging Spectrograph Authors: Mikuła, K.; Heinzel, P.; Liu, W.; Berlicki, A. Bibcode: 2017ApJ...845...30M Altcode: Flare loops were well observed with the Interface Region Imaging Spectrograph (IRIS) during the gradual phase of two solar flares on 2014 March 29 and 2015 June 22. Cool flare loops are visible in various spectral lines formed at chromospheric and transition-region temperatures and exhibit large downflows which correspond to the standard scenario. The principal aim of this work is to analyze the structure and dynamics of cool flare loops observed in Mg II lines. Synthetic profiles of the Mg II h line are computed using the classical cloud model and assuming a uniform background intensity. In this paper, we study novel IRIS NUV observations of such loops in Mg II h and k lines and also show the behavior of hotter lines detected in the FUV channel. We obtained the spatial evolution of the velocities: near the loop top, the flow velocities are small and they are increasing toward the loop legs. Moreover, from slit-jaw image (SJI) movies, we observe some plasma upflows into the loops, which are also detectable in Mg II spectra. The brightness of the loops systematically decreases with increasing flow velocity, and we ascribe this to the effect of Doppler dimming, which works for Mg II lines. Emission profiles of Mg II were found to be extremely broad, and we explain this through the large unresolved non-thermal motions. Title: Recruiting flare hunters for citizen science Authors: Fletcher, Lyndsay; Berlicki, Arkadiusz; Awasthi, Arun Kumar; Gronkiewicz, Dominik Bibcode: 2016A&G....57f6.21F Altcode: Lyndsay Fletcher, Arkadiusz Berlicki, Arun Kumar Awasthi and Dominik Gronkiewicz describe how they established F-HUNTERS, a pro-am solar flare observing campaign. Title: Height formation of bright points observed by IRIS in Mg II line wings during flux emergence Authors: Grubecka, M.; Schmieder, B.; Berlicki, A.; Heinzel, P.; Dalmasse, K.; Mein, P. Bibcode: 2016A&A...593A..32G Altcode: Context. A flux emergence in the active region AR 111850 was observed on September 24, 2013 with the Interface Region Imaging Spectrograph (IRIS). Many bright points are associated with the new emerging flux and show enhancement brightening in the UV spectra.
Aims: The aim of this work is to compute the altitude formation of the compact bright points (CBs) observed in Mg II lines in the context of searching Ellerman bombs (EBs).
Methods: IRIS provided two large dense rasters of spectra in Mg II h and k lines, Mg II triplet, C II and Si IV lines covering all the active region and slit jaws in the two bandpasses (1400 Å and 2796 Å) starting at 11:44 UT and 15:39 UT, and lasting 20 min each. Synthetic profiles of Mg II and Hα lines are computed with non-local thermodynamic equlibrium (NLTE) radiative transfer treatment in 1D solar atmosphere model including a hotspot region defined by three parameters: temperature, altitude, and width.
Results: Within the two IRIS rasters, 74 CBs are detected in the far wings of the Mg II lines (at +/-1 Å and 3.5 Å). Around 10% of CBs have a signature in Si IV and CII. NLTE models with a hotspot located in the low atmosphere were found to fit a sample of Mg II profiles in CBs. The Hα profiles computed with these Mg II CB models are consistent with typical EB profiles observed from ground based telescopes e.g. THEMIS. A 2D NLTE modelling of fibrils (canopy) demonstrates that the Mg II line centres can be significantly affected but not the peaks and the wings of Mg II lines.
Conclusions: We conclude that the bright points observed in Mg II lines can be formed in an extended domain of altitudes in the photosphere and/or the chromosphere (400 to 750 km). Our results are consistent with the theory of heating by Joule dissipation in the atmosphere produced by magnetic field reconnection during flux emergence. Title: Flares In Time-Domain Surveys Authors: Kowalski, Adam; Hawley, Suzanne; Davenport, James; Berlicki, Arkadiusz; Cauzzi, Gianna; Fletcher, Lyndsay; Heinzel, Petr; Notsu, Yuta; Loyd, Parke; Martinez Oliveros, Juan Carlos; Pugh, Chloe; Schmidt, Sarah Jane; Karmakar, Subhajeet; Pye, John; Flaccomio, Ettore Bibcode: 2016csss.confE.126K Altcode: Proceedings for the splinter session "Flares in Time-Domain Surveys" convened at Cool Stars 19 on June 07, 2016 in Uppsala, Sweden. Contains a two page summary of the splinter session, links to YouTube talks, and a PDF copy of the slides from the presenters. Title: Astronomy popularization at the University of Wrocław Authors: Preś, Paweł; Cader-Sroka, Barbara; Berlicki, Arkadiusz Bibcode: 2016pas..conf..267P Altcode: Science popularization found many expressions in the history of the Astronomical Institute of the University of Wrocław. The long-lasting is the tradition of popular astronomy lectures. Occasional celestial events are the base of public observations. Since 1998 the Institute boldly participates in the Lower-Silesian Science Festival. The rising public interest in astronomy encouraged us to establish ''Planetarium'' laboratory in 2008. Together with the Astronomical Institute of the Academy of Sciences of the Czech Republic we established in 2009 the very first trans-border dark-sky park in the location of Izera Mountains, where since then the public can benefit from excellent observational conditions and the astronomers' support. Title: Observations and modeling of the ultraviolet emission of solar flares Authors: Mikuła, Katarzyna; Berlicki, Arkadiusz; Heinzel, Petr Bibcode: 2016IAUS..320...57M Altcode: In this paper we present the method of using far UV spectra of the flare observed by Interface Region Imaging Spectrograph (IRIS) for determination of the contribution of the continuum emission to the total UV radiation observed e.g. by SDO in 1600 Å channel. In our method the Si IV (1402.77 Å) line observed by IRIS is used as a proxy of C IV line emission contained in SDO/AIA UV images. Determined intensity of the flare continuum emission can be used to study the physics of the flare heated chromosphere and for better understanding of the emission mechanisms. Title: White-light continuum emission from a solar flare and plage Authors: Berlicki, Arkadiusz; Awasthi, Arun Kumar; Heinzel, Petr; Sobotka, Michal Bibcode: 2016IAUS..320..268B Altcode: 2016arXiv160404186B Observations of flare emissions in the optical continuum are very rare. Therefore, the analysis of such observations is useful and may contribute to our understanding of the flaring chromosphere and photosphere. We study the white light continuum emission observed during the X6.9 flare. This emission comes not only from the flare ribbons but also form the nearby plage area. The main aim of this work is to disentangle the flare and plage (facula) emission. We analyzed the spatial, spectral and temporal evolution of the flare and plage properties by analyzing multi-wavelength observations. We study the morphological correlation of the white-light continuum emission observed with different instruments. We found that some active region areas which produce the continuum emission correspond rather to plages than to the flare kernels. We showed that in some cases the continuum emission from the WL flare kernels is very similar to the continuum emission of faculae. Title: White-light continuum emission from solar flare and plages: observations and modeling Authors: Berlicki, Arkadiusz; Awasthi, Arun Kumar; Heinzel, Petr Bibcode: 2015IAUGA..2256469B Altcode: Observations of flares in optical continuum emission are very rare. Therefore, the analysis of such observations is very useful and may contribute to our understanding of the flaring chromosphere. We study the white-light continuum emission observed during the X6.9 flare observed on August 09, 2011. This emission comes not only from the flare ribbons but also form the nearby plage area observed within the active region. The main aim of this work is to disentangle the flare and plage emission and to understand the physical mechanisms responsible for the production of white-light continuum.There are two main mechanisms which can be responsible for the optical continuum emission of the solar atmosphere: enhanced photospheric H- continuum due to the temperature increase below the temperature minimum region, or hydrogen recombination continua (Balmer, Paschen) formed in solar chromosphere. In our work we analyse the physical conditions in solar active atmosphere in order to obtain the contribution from these two mechanisms to the whole continuum emission of the flare and plage.We analyzed the spatial, spectral and temporal evolution study of the flare and plage parameters by analyzing multi-wavelength observations obtained from ground and space based solar observatories. We study the morphological correlation of the white-light continuum emission observed with different instruments. Moreover, we also explore the non-thermal electron beam properties by forward fitting the observed X-ray spectra.The unique opportunity of an intense X6.9 flare occurrence close to the limb enabled us to explore the origin of white-light continuum with better visibility. The analysis of multi-wavelength data revealed the origin of this emission from the foot-points of the loops. Spatial association of HXR foot-points synthesized from RHESSI observations confirmed this finding. In addition, we found a good temporal correlation of hard (>30 keV) X-ray with the white-light emission. However, some active region areas which produce the continuum emission correspond rather to plages than to the flare kernels. Title: Multi-wavelength diagnostics and modelling of the emission during a B6.4 flare of August 20, 2005 Authors: Awasthi, Arun Kumar; Berlicki, Arkadiusz; Rudawy, Powel; Heinzel, Petr Bibcode: 2015IAUGA..2256580A Altcode: We study the temporal, spatial and spectral evolution of multi-wavelength emission observed during a B6.4 flare occurred on August 20, 2005 with the motivation to outline the thermal and non-thermal processes during the precursor and gradual phase of the flare. Precursor phase is designated as the gradual enhancement of soft X-ray emission prior to onset of the impulsive phase. Observations from several space and ground based observatories viz. RHESSI, TRACE, GONG, SoHO/EIT and NoRP are included in this study. Temporal evolution of X-ray emission does not show the presence of hard X-rays (>12 keV) emission during the precursor phase of the flare. We synthesized X-ray images in 6-12 keV from RHESSI observations, which show several discrete sources during the precursor phase. Following to this, one of these sources pronounced during the main phase of the flare. We carry out in-depth analysis of chromospheric response in various phases of the flare employing high temporal cadence images of the Sun in Hα line centre as well as wings obtained from the Multi-channel Subtractive Double Pass Spectrograph (MSDP) at the Bialkow Observatory of the University of Wroclaw, Poland. Our analysis of Hα images during the main phase of the flare suggests localized emission in the form of kernels. On the contrary, we note extended and diffused source morphology of emitting region during the precursor phase of the flare. We also study various kinematic properties of different structures visible in the Hα images in the line centre as well as wings. In addition, the correlation of the relative timing of X-ray and Hα emission profile is performed to estimate the delay in the chromospheric response during different phases of flare. Further, we employ thermal plasma parameters estimated during the precursor and gradual phase to model the associated Hα emission. For the modeling we employ NLTE numerical codes modified for flare conditions. The modeled and observed flare emission parameters are then compared. Finally, we propose a unified schematic scenario for the trigger and energy release during this low-intensity class flare. Title: Observations and modeling of the ultraviolet emission of solar flares Authors: Berlicki, Arkadiusz; Heinzel, Petr; Mikula, Katarzyna Bibcode: 2015IAUGA..2257337B Altcode: It is well known that during solar flares the heated chromospheric plasma emits the ultraviolet (UV) radiation in spectral lines and continua. UV space telescopes (e.g. TRACE, Solar Dynamic Observatory/Atmospheric Imaging Assembly - SDO/AIA) provide images of solar flares where the complicated fine structure of the flaring atmosphere is well visible. However, these broadband images contain the mixture of line and continuum UV emission and it is not possible to disentangle between these two contributions. E.g. solar flare brightening observed in SDO/AIA 160 nm channel can be visible both due to the strong line emission in C IV 154.8 nm or due to the continuum increase. Spectral lines and continua are formed in plasma of different temperature and location. Therefore, in order to obtain the parameters of plasma we should know quantitatively the contribution from lines and continua.Such analysis would be possible using the UV spectrograph, where we can see the intensity of lines and continua separately. For example Interface Region Imaging Spectrograph (IRIS) provides such spectra of flares, where the enhanced lines and continuum is visible both in NUV (near UV) and FUV (far UV) channels.In our work we used IRIS flare observations in FUV channel to determine the intensity of spectral lines, including Si IV 139.4 nm line. Then, using CHIANTI procedures and the observed intensities of some FUV lines we computed the synthetic UV spectrum for given flare model. IRIS spectrum does not include C IV line, which contaminates the SDO/AIA images, but this line can be calculated in the theoretical CHIANTI spectrum. In this way, we can subtract the C IV (and other lines) emission from SDO/AIA images and obtain the pure UV continuum intensity. Finally, the obtained continuum emission can used to study the physics of heated chromosphere of flares. Title: Dark Sky Protection and Education - Izera Dark Sky Park Authors: Berlicki, Arkadiusz; Kolomanski, Sylwester; Mrozek, Tomasz; Zakowicz, Grzegorz Bibcode: 2015IAUGA..2257138B Altcode: Darkness of the night sky is a natural component of our environment and should be protected against negative effects of human activities. The night darkness is necessary for balanced life of plants, animals and people. Unfortunately, development of human civilization and technology has led to the substantial increase of the night-sky brightness and to situation where nights are no more dark in many areas of the World. This phenomenon is called "light pollution" and it can be rank among such problems as chemical pollution of air, water and soil. Besides the environment, the light pollution can also affect e.g. the scientific activities of astronomers - many observatories built in the past began to be located within the glow of city lights making the night observations difficult, or even impossible.In order to protect the natural darkness of nights many so-called "dark sky parks" were established, where the darkness is preserved, similar to typical nature reserves. The role of these parks is not only conservation but also education, supporting to make society aware of how serious the problem of the light pollution is.History of the dark sky areas in Europe began on November 4, 2009 in Jizerka - a small village situated in the Izera Mountains, when Izera Dark Sky Park (IDSP) was established - it was the first transboundary dark sky park in the World. The idea of establishing that dark sky park in the Izera Mountains originated from a need to give to the society in Poland and Czech Republic the knowledge about the light pollution. Izera Dark Sky Park is a part of the astro-tourism project "Astro Izery" that combines tourist attraction of Izera Valley and astronomical education under the wonderful starry Izera sky. Besides the IDSP, the project Astro Izery consists of the set of simple astronomical instruments (gnomon, sundial), natural educational trail "Solar System Model", and astronomical events for the public. In addition, twice a year we organize a 3-4 days "Astronomy Workshop for Schools", where teachers and astronomers from Astronomical Institute (University of Wroclaw) educate the young generations in the field of astronomy and other physical sciences. Title: On the Visibility of Prominence Fine Structures at Radio Millimeter Wavelengths Authors: Heinzel, P.; Berlicki, A.; Bárta, M.; Karlický, M.; Rudawy, P. Bibcode: 2015SoPh..290.1981H Altcode: 2015SoPh..tmp...87H Prominence temperatures have so far mainly been determined by analyzing spectral line shapes, which is difficult when the spectral lines are optically thick. The radio spectra in the millimeter range offer a unique possibility to measure the kinetic temperature. However, studies in the past used data with insufficient spatial resolution to resolve the prominence fine structures. The aim of this article is to predict the visibility of prominence fine structures in the submillimeter/millimeter (SMM) domain, to estimate their brightness temperatures at various wavelengths, and to demonstrate the feasibility and usefulness of future high-resolution radio observations of solar prominences with ALMA (Atacama Large Millimeter-submillimeter Array). Our novel approach is the conversion of Hα coronagraphic images into microwave spectral images. We show that the spatial variations of the prominence brightness both in the Hα line and in the SMM domain predominantly depend on the line-of-sight emission measure of the cool plasma, which we derive from the integrated intensities of the observed Hα line. This relation also offers a new possibility to determine the SMM optical thickness from simultaneous Hα observations with high resolution. We also describe how we determine the prominence kinetic temperature from SMM spectral images. Finally, we apply the ALMA image-processing software Common Astronomy Software Applications (CASA) to our simulated images to assess what ALMA would detect at a resolution level that is similar to the coronagraphic Hα images used in this study. Our results can thus help in preparations of first ALMA prominence observations in the frame of science and technical verification tests. Title: Observations and NLTE modeling of Ellerman bombs Authors: Berlicki, A.; Heinzel, P. Bibcode: 2014A&A...567A.110B Altcode: 2014arXiv1406.5702B Context. Ellerman bombs (EBs) are short-lived, compact, and spatially well localized emission structures that are observed well in the wings of the hydrogen Hα line. EBs are also observed in the chromospheric CaII lines and in UV continua as bright points located within active regions. Hα line profiles of EBs show a deep absorption at the line center and enhanced emission in the line wings with maxima around ±1 Å from the line center. Similar shapes of the line profiles are observed for the CaII IR line at 8542 Å. In CaII H and K lines the emission peaks are much stronger, and EBs emission is also enhanced in the line center.
Aims: It is generally accepted that EBs may be considered as compact microflares located in lower solar atmosphere that contribute to the heating of these low-lying regions, close to the temperature minimum of the atmosphere. However, it is still not clear where exactly the emission of EBs is formed in the solar atmosphere. High-resolution spectrophotometric observations of EBs were used for determining of their physical parameters and construction of semi-empirical models. Obtained models allow us to determine the position of EBs in the solar atmosphere, as well as the vertical structure of the activated EB atmosphere
Methods: In our analysis we used observations of EBs obtained in the Hα and CaII H lines with the Dutch Open Telescope (DOT). These one-hour long simultaneous sequences obtained with high temporal and spatial resolution were used to determine the line emissions. To analyze them, we used NLTE numerical codes for the construction of grids of 243 semi-empirical models simulating EBs structures. In this way, the observed emission could be compared with the synthetic line spectra calculated for all such models.
Results: For a specific model we found reasonable agreement between the observed and theoretical emission and thus we consider such model as a good approximation to EBs atmospheres. This model is characterized by an enhanced temperature in the lower chromosphere and can be considered as a compact structure (hot spot), which is responsible for the emission observed in the wings of chromospheric lines, in particular in the Hα and CaII H lines.
Conclusions: For the first time the set of two lines Hα and CaII H was used to construct semi-empirical models of EBs. Our analysis shows that EBs can be described by a "hot spot" model, with the temperature and/or density increase through a few hundred km atmospheric structure. We confirmed that EBs are located close to the temperature minimum or in the lower chromosphere. Two spectral features (lines in our case), observed simultaneously, significantly strengthen the constraints on a realistic model. Title: F-CHROMA.Flare Chromospheres: Observations, Models and Archives Authors: Cauzzi, Gianna; Fletcher, Lyndsay; Mathioudakis, Mihalis; Carlsson, Mats; Heinzel, Petr; Berlicki, Arek; Zuccarello, Francesca Bibcode: 2014AAS...22412339C Altcode: F-CHROMA is a collaborative project newly funded under the EU-Framework Programme 7 "FP7-SPACE-2013-1", involving seven different European research Institutes and Universities. The goal of F-CHROMA is to substantially advance our understanding of the physics of energy dissipation and radiation in the flaring solar atmosphere, with a particular focus on the flares' chromosphere. A major outcome of the F-CHROMA project will be the creation of an archive of chromospheric flare observations and models to be made available to the community for further research.In this poster we describe the structure and milestones of the project, the different activities planned, as well as early results. Emphasis will be given to the dissemination efforts of the project to make results of these activities available to and usable by the community. Title: Multi Element Telescope for Imaging and Spectroscopy (METIS) coronagraph for the Solar Orbiter mission Authors: Antonucci, Ester; Fineschi, Silvano; Naletto, Giampiero; Romoli, Marco; Spadaro, Daniele; Nicolini, Gianalfredo; Nicolosi, Piergiorgio; Abbo, Lucia; Andretta, Vincenzo; Bemporad, Alessandro; Auchère, Frédéric; Berlicki, Arkadiusz; Bruno, Roberto; Capobianco, Gerardo; Ciaravella, Angela; Crescenzio, Giuseppe; Da Deppo, Vania; D'Amicis, Raffaella; Focardi, Mauro; Frassetto, Fabio; Heinzel, Peter; Lamy, Philippe L.; Landini, Federico; Massone, Giuseppe; Malvezzi, Marco A.; Moses, J. Dan; Pancrazzi, Maurizio; Pelizzo, Maria-Guglielmina; Poletto, Luca; Schühle, Udo H.; Solanki, Sami K.; Telloni, Daniele; Teriaca, Luca; Uslenghi, Michela Bibcode: 2012SPIE.8443E..09A Altcode: METIS, the “Multi Element Telescope for Imaging and Spectroscopy”, is a coronagraph selected by the European Space Agency to be part of the payload of the Solar Orbiter mission to be launched in 2017. The unique profile of this mission will allow 1) a close approach to the Sun (up to 0.28 A.U.) thus leading to a significant improvement in spatial resolution; 2) quasi co-rotation with the Sun, resulting in observations that nearly freeze for several days the large-scale outer corona in the plane of the sky and 3) unprecedented out-of-ecliptic view of the solar corona. This paper describes the experiment concept and the observational tools required to achieve the science drivers of METIS. METIS will be capable of obtaining for the first time: • simultaneous imaging of the full corona in polarized visible-light (590-650 nm) and narrow-band ultraviolet HI Lyman α (121.6 nm); • monochromatic imaging of the full corona in the extreme ultraviolet He II Lyman α (30.4 nm); • spectrographic observations of the HI and He II Ly α in corona. These measurements will allow a complete characterization of the three most important plasma components of the corona and the solar wind, that is, electrons, hydrogen, and helium. This presentation gives an overview of the METIS imaging and spectroscopic observational capabilities to carry out such measurements. Title: METIS: a novel coronagraph design for the Solar Orbiter mission Authors: Fineschi, Silvano; Antonucci, Ester; Naletto, Giampiero; Romoli, Marco; Spadaro, Daniele; Nicolini, Gianalfredo; Abbo, Lucia; Andretta, Vincenzo; Bemporad, Alessandro; Berlicki, Arkadiusz; Capobianco, Gerardo; Crescenzio, Giuseppe; Da Deppo, Vania; Focardi, Mauro; Landini, Federico; Massone, Giuseppe; Malvezzi, Marco A.; Moses, J. Dan; Nicolosi, Piergiorgio; Pancrazzi, Maurizio; Pelizzo, Maria-Guglielmina; Poletto, Luca; Schühle, Udo H.; Solanki, Sami K.; Telloni, Daniele; Teriaca, Luca; Uslenghi, Michela Bibcode: 2012SPIE.8443E..3HF Altcode: METIS (Multi Element Telescope for Imaging and Spectroscopy) METIS, the “Multi Element Telescope for Imaging and Spectroscopy”, is a coronagraph selected by the European Space Agency to be part of the payload of the Solar Orbiter mission to be launched in 2017. The mission profile will bring the Solar Orbiter spacecraft as close to the Sun as 0.3 A.U., and up to 35° out-of-ecliptic providing a unique platform for helio-synchronous observations of the Sun and its polar regions. METIS coronagraph is designed for multi-wavelength imaging and spectroscopy of the solar corona. This presentation gives an overview of the innovative design elements of the METIS coronagraph. These elements include: i) multi-wavelength, reflecting Gregorian-telescope; ii) multilayer coating optimized for the extreme UV (30.4 nm, HeII Lyman-α) with a reflecting cap-layer for the UV (121.6 nm, HI Lyman-α) and visible-light (590-650); iii) inverse external-occulter scheme for reduced thermal load at spacecraft peri-helion; iv) EUV/UV spectrograph using the telescope primary mirror to feed a 1st and 4th-order spherical varied line-spaced (SVLS) grating placed on a section of the secondary mirror; v) liquid crystals electro-optic polarimeter for observations of the visible-light K-corona. The expected performances are also presented. Title: Velocity Vector, Ionization Degree, and Temperature of Prominence Fine Structures Observed by Hinode/SOT Authors: Schmieder, B.; Mein, P.; Chandra, R.; Molodij, G.; Heinzel, P.; Berlicki, A.; Schwartz, P.; Fárník, F.; Labrosse, N.; Anzer, U.; Watanabe, T. Bibcode: 2012ASPC..454..107S Altcode: Prominences have been successfully observed by Hinode in April 2007 exhibiting a strong dynamics of their fine structures. The dynamics of a prominence is a challenge to understand the formation of cool prominence plasma embedded in the hot corona. Combining simultaneous observations obtained in Hα with Hinode/SOT and the MSDP spectrograph operating at the Meudon solar tower, velocity vectors have been derived. The Doppler-shifts of bright threads are of the same order as the velocities measured perpendicular to the line of sight. This suggests that the vertical structures of the prominence could be a pile up of dips in magnetic field lines viewed in 3D. Using Hα, Hinode/XRT and TRACE data, the hydrogen ionization degree has been determined to be 0.5-0.8, and the optical thickness in Hα between 0.2 and 1.3. The Extreme Ultraviolet Imaging Spectrometer (EIS) on Hinode produced images of the prominence in 11 selected lines with formation temperatures between log(T) = 4.7 and log(T) = 6.1. We comment on the absorption, emissivity blocking and emission involved for interpreting the different structures of the prominence in terms of the temperature and density. Title: 2D radiative-magnetohydrostatic model of a prominence observed by Hinode, SoHO/SUMER and Meudon/MSDP Authors: Berlicki, A.; Gunar, S.; Heinzel, P.; Schmieder, B.; Schwartz, P. Bibcode: 2011A&A...530A.143B Altcode:
Aims: Prominences observed by Hinode show very dynamical and intriguing structures. To understand the mechanisms that are responsible for these moving structures, it is important to know the physical conditions that prevail in fine-structure threads. In the present work we analyse a quiescent prominence with fine structures, which exhibits dynamic behaviour, which was observed in the hydrogen Hα line with Hinode/SOT, Meudon/MSDP and Ondřejov/HSFA2, and simultaneously in hydrogen Lyman lines with SoHO/SUMER during a coordinated campaign. We derive the fine-structure physical parameters of this prominence and also address the questions of the role of the magnetic dips and of the interpretation of the flows.
Methods: We calibrate the SoHO/SUMER and Meudon/MSDP data and obtain the line profiles of the hydrogen Lyman series (Lβ to L6), the Ciii (977.03 Å) and Svi (933.40 Å), and Hα along the slit of SoHO/SUMER that crosses the Hinode/SOT prominence. We employ a complex 2D radiation-magnetohydrostatic (RMHS) modelling technique to properly interpret the observed spectral lines and derive the physical parameters of interest. The model was constrained not only with integrated intensities of the lines, but also with the hydrogen line profiles.
Results: The slit of SoHO/SUMER is crossing different prominence structures: threads and dark bubbles. Comparing the observed integrated intensities, the depressions of Hα bubbles are clearly identified in the Lyman, Ciii, and Svi lines. To fit the observations, we propose a new 2D model with the following parameters: T = 8000 K, pcen = 0.035 dyn cm-2, B = 5 Gauss, ne = 1010 cm-3, 40 threads each 1000 km wide, plasma β is 3.5 × 10-2.
Conclusions: The analysis of Ciii and Svi emission in dark Hα bubbles allows us to conclude that there is no excess of a hotter plasma in these bubbles. The new 2D model allows us to diagnose the orientation of the magnetic field versus the LOS. The 40 threads are integrated along the LOS. We demonstrate that integrated intensities alone are not sufficient to derive the realistic physical parameters of the prominence. The profiles of the Lyman lines and also those of the Hα line are necessary to constrain 2D RMHS models. The magnetic field in threads is horizontal, perpendicular to the LOS, and in the form of shallow dips. With this geometry the dynamics of fine structures in prominences could be interpreted by a shrinkage of the quasi-horizontal magnetic field lines and apparently is not caused by the quasi-vertical bulk flows of the plasma, as Hinode/SOT movies seemingly suggest. Title: Multi-wavelength analysis of Ellerman Bomb Light Curves Authors: Herlender, M.; Berlicki, A. Bibcode: 2011CEAB...35..181H Altcode: We present the results of a multi-wavelength photometric analysis of Ellerman Bomb (EB) observations obtained from the Dutch Open Telescope. In our data we have found 6 EBs located in the super-penumbra of the main spot in the active region NOAA 10781. We present light curves of EB observed in the Hα line centre and wing +0.7 Å, in the Ca II H line centre and wing~+2.35 Å, in the G-band and in the TRACE 1600 Å filter. We have shown that EBs were visible in the G-band and moreover, there was a good correlation between the light curves in the G-band and in the Hα line wings. We also found quasi-periodic oscillations of EBs brightness in the G-band, CaII H line and TRACE 1600 Å filter. Title: Solar Flares and the Chromosphere Authors: Fletcher, L.; Turkmani, R.; Hudson, H. S.; Hawley, S. L.; Kowalski, A.; Berlicki, A.; Heinzel, P. Bibcode: 2010arXiv1011.4650F Altcode: A white paper prepared for the Space Studies Board, National Academy of Sciences (USA), for its Decadal Survey of Solar and Space Physics (Heliophysics), reviewing and encouraging studies of flare physics in the chromosphere. Title: Solar Flares and the Chromosphere: A white paper for the Decadal Survey Authors: Hudson, H. S.; Fletcher, L.; Turkmani, R.; Hawley, S. L.; Kowalski, A. F.; Berlicki, A.; Heinzel, P. Bibcode: 2010helio2010....1H Altcode: No abstract at ADS Title: Flare Energy Build-Up in a Decaying Active Region Near a Coronal Hole Authors: Su, Yingna; van Ballegooijen, Adriaan; Schmieder, Brigitte; Berlicki, Arkadiusz; Guo, Yang; Golub, Leon; Huang, Guangli Bibcode: 2010shin.confE.131S Altcode: A B1.7 two-ribbon flare occurred in a highly non-potential decaying active region near a coronal hole at 10:00 UT on May 17, 2008. This flare is large in the sense that it involves the entire region, and it is associated with both a filament eruption and a CME. We present multi-wavelength observations from EUV (TRACE, STEREO/EUVI), X-rays (Hinode/XRT), and H-alpha (THEMIS, BBSO) prior to, during and after the flare. Prior to the flare, the region contained two filaments. The long J-shaped sheared loops corresponding to the southern filament were evolved from two short loop systems, which happened around 22:00 UT after a filament eruption on May 16. Formation of highly sheared loops in the south eastern part of the region was observed by STEREO 8 hours before the flare. We also perform non-linear force free field (NLFFF) modeling for the region at two times prior to the flare, using the flux rope insertion method. The models include the non-force-free effect of magnetic buoyancy in the photosphere. The best-fit NLFFF models show good fit to observations both in the corona (X-ray and EUV loops) and chromosphere (H-alpha filament). We find that the horizontal fields in the photosphere are relatively insensitive to the present of flux ropes in the corona. The axial flux of the flux rope in the NLFFF model on May 17 is twice that on May 16, and the model on May 17 is only marginally stable. We also find that the quasi-circular flare ribbons are associated with the separatrix between open and closed fields. This observation and NLFFF modeling suggest that this flare may be triggered by the reconnection at the null point on the separatrix surface. Title: Velocity vectors of a quiescent prominence observed by Hinode/SOT and the MSDP (Meudon) Authors: Schmieder, B.; Chandra, R.; Berlicki, A.; Mein, P. Bibcode: 2010A&A...514A..68S Altcode: 2009arXiv0911.5091S Context. The dynamics of prominence fine structures present a challenge to our understanding of the formation of cool plasma prominence embedded in the hot corona.
Aims: Observations performed by the high resolution Hinode/SOT telescope allow us to compute velocities perpendicular to the line-of-sight or transverse velocities. Combining simultaneous observations obtained in Hα with Hinode/SOT and the MSDP spectrograph operating in the Meudon solar tower, we derive the velocity vectors of a quiescent prominence.
Methods: The velocities perpendicular to the line-of-sight are measured using a time-slice technique and the Doppler shifts velocity using the bisector method.
Results: The Doppler shifts of bright threads derived from the MSDP show counterstreaming of the order of 5 km s-1 in the prominence and reaching 15 km s-1 at the edges of the prominence. Even though they are minimum values because of seeing effects, they are of the same order as the transverse velocities.
Conclusions: These measurements are very important because they suggest that the vertical structures detected by SOT may not be true vertical magnetic structures in the sky plane. The vertical structures could be a pile up of dips in more or less horizontal magnetic field lines in a 3D perspective, as proposed by many MHD modelers. In our analysis, we also calibrate the Hinode Hα data using MSDP observations obtained simultaneously.

A movie is available in electronic form at http://www.aanda.org Title: Counterstreaming in quiescent prominences observed by Hinode/SOT and Meudon/MSDP Authors: Schmieder, Brigitte; Chandra, Ramesh; Berlicki, Arkadiusz; Mein, Pierre Bibcode: 2010cosp...38.2943S Altcode: 2010cosp.meet.2943S Prominences have been successfully observed by Hinode in April 2007 exhibiting a strong dy-namics of their fine structures. The dynamics of a prominence is a challenge to understand the formation of cool prominence plasma embedded in the hot corona. Combining simultaneous observations obtained in Hα with Hinode/SOT and the MSDP spectrograph operating at the Meudon solar tower, velocity vectors have been derived. The Doppler-shifts of bright threads are of the same order as the transverse velocities measured perpendicularly to the line of sight. Counterstreamings are detected at the top of the prominence. The vertical structures of the prominence could be a pile up of dips in magnetic field lines viewed in 3D Title: Relations between theoretical and observational plasma parameters and the radiation of the prominence Authors: Berlicki, Arkadiusz; Schwartz, Pavol; Schmieder, Brigitte; Heinzel, Petr; Gunar, Stanislav Bibcode: 2010cosp...38.2945B Altcode: 2010cosp.meet.2945B On April 26, 2007 the quiescent prominence was observed during the coordinated campaign of prominence studies icluding SOT, XRT, and EIS on Hinode, MDI, EIT, SUMER, and CDS on SOHO, TRACE, and several ground-based observatories. This was the first Hinode-SUMER ob-serving campaign. In this analysis we use the data obtained with Hinode/SOT, SOHO/SUMER and Multichannel Spectrograph MSDP (Meudon, France). The SUMER instrument provide us the UV spectra of the prominence in several spectral lines along the 120 arcsec slit crossing the prominence. We used the following lines: Lβ, Lγ, Lδ, L , C III and S VI. Using these spectra we calculated the integrated intensities along the slit for all these lines. We also calculated the integrated intensity of the Hα line from the spectroscopic ground-based MSDP observations for the same parts of the prominence observed at the same time. These intensities were used to calibrate the Hinode/SOT data. Next, we analyzed the relations between different observed intensities in these lines and compared them with the values obtained from the theoretical simulations. We analyzed the correlations between observations and theoretical modeling and as a results we estimated the different physical parameters of the prominence plasma. Title: Photometric analysis of Ellerman bombs . Authors: Berlicki, A.; Heinzel, P.; Avrett, E. H. Bibcode: 2010MmSAI..81..646B Altcode: Observations of Ellerman bombs (EBs) show them as short-lived, compact, and spatially localized emissions that are well observable in the wings of the Halpha hydrogen line. The Halpha line profiles of EBs are characterized by deep absorption at the line center and enhanced emission in the wings with maximum around ± 1 Å from the line center, fading beyond ± 5 Å. EBs may also be observed in the chromospheric Ca II lines and in the UV as bright points often located within active regions. Previous work suggests that EBs may be considered as micro-flares and may contribute significantly to the heating of the lower chromosphere in newly emerging magnetic flux regions. However, it is still not clear at what height in the solar atmosphere the emission of EBs originates. In our analysis we used observations of EBs obtained in the Halpha line with the Dutch Open Telescope (DOT) and in the UV range with the TRACE 1600 Å channel. These one-hour long simultaneous sequences obtained with high temporal and spatial resolution were used to analyze the relation between the emission in the Halpha line and at 1600 Å. The observations show fast variations of EB emission in both channels. Comparison between the observed emission in Halpha and at 1600 Å and theoretical calculations allowed us to draw conclusions about the vertical structure of EBs. Title: Spectrophotometric Analysis of an Ellerman bomb Authors: Herlender, M.; Berlicki, A. Bibcode: 2010CEAB...34...65H Altcode: In this paper we present results of spectrophotometric analysis of an Ellerman bomb (EB), which was observed on June 5, 2003 in the active region NOAA 10735. The observations were made in the Hα line using the spectro-imager MSDP mode of the Large Coronograph of The Observatory of Astronomical Institute of the University of Wrocław. The observed EB was located near the foot-point of an arch filament system, and was observed for three hours showing five individual peaks of brightness. We present the light curve at five wavelengths from the Hα line centre to Hα+0.8 Å with a step of 0.2 Å. We also present profiles of the Hα line of the EB at different stages of their evolution. At those profiles one can see that, there is characteristic excess of emission in the Hα line wings. In addition, when the line wings are brighter, the intensity of the Hα line centre is weaker. Title: Flare Energy Build-up in a Decaying Active Region Near a Coronal Hole Authors: Su, Yingna; van Ballegooijen, Adriaan; Schmieder, Brigitte; Berlicki, Arkadiusz; Guo, Yang; Golub, Leon; Huang, Guangli Bibcode: 2009ApJ...704..341S Altcode: A B1.7 two-ribbon flare occurred in a highly non-potential decaying active region near a coronal hole at 10:00 UT on 2008 May 17. This flare is "large" in the sense that it involves the entire region, and it is associated with both a filament eruption and a coronal mass ejection. We present multi-wavelength observations from EUV (TRACE, STEREO/EUVI), X-rays (Hinode/XRT), and Hα (THEMIS, BBSO) prior to, during and after the flare. Prior to the flare, the region contained two filaments. The long J-shaped sheared loops corresponding to the southern filament were evolved from two short loop systems, which happened around 22:00 UT after a filament eruption on May 16. Formation of highly sheared loops in the southeastern part of the region was observed by STEREO 8 hr before the flare. We also perform nonlinear force-free field (NLFFF) modeling for the region at two times prior to the flare, using the flux rope insertion method. The models include the non-force-free effect of magnetic buoyancy in the photosphere. The best-fit NLFFF models show good fit to observations both in the corona (X-ray and EUV loops) and chromosphere (Hα filament). We find that the horizontal fields in the photosphere are relatively insensitive to the present of flux ropes in the corona. The axial flux of the flux rope in the NLFFF model on May 17 is twice that on May 16, and the model on May 17 is only marginally stable. We also find that the quasi-circular flare ribbons are associated with the separatrix between open and closed fields. This observation and NLFFF modeling suggest that this flare may be triggered by the reconnection at the null point on the separatrix surface. Title: Magnetic Nonpotentiality Accumulation Prior to a "Large" B1.7 Two-Ribbon Flare Authors: Su, Yingna; van Ballegooijen, A.; Schmieder, B.; Berlicki, A.; Guo, Y.; Golub, L. Bibcode: 2009SPD....40.2002S Altcode: A B1.7 two-ribbon flare occurred in a highly non-potential decaying active region near a coronal hole at 10:00 UT on May 17, 2008. This flare is "large" in the sense that it involves the entire region, and it is associated with both a filament eruption and a CME. We present multi-wavelength observations from EUV (TRACE, STEREO/EUVI), X-rays (Hinode/XRT), and H-alpha (THEMIS, BBSO) prior to, during and after the flare. Prior to the flare, the observed coronal loops are mainly two sets of highly sheared loops surrounding two filaments. The sheared loops in the southern part of the region appeared in TRACE around 22:00 UT after a filament ejection on May 16. We also performed non-linear force free field (NLFFF) modeling for the region prior to the flare, using the flux rope insertion method. The model at 11:42 UT on May 16 is based on THEMIS (vector) and MDI magnetograms, and the model at 08:03 UT on May 17 is based only on MDI magnetogram. The best-fit NLFFF models show good fit to observations both in the corona (X-ray and EUV loops) and chromosphere (H-alpha filament). In the photosphere, the vectors in the best-fit NLFFF model are similar to those in the potential model. However, in the chromosphere, the vectors in the best-fit NLFFF model present strong non-potentiality, especially at the end of the inserted flux rope. We also found that the axial flux of the flux rope in the NLFFF model on May 17 is much higher than that on May 16. Title: NLTE modelling of the flaring atmosphere above sunspot Authors: Berlicki, A.; Heinzel, P.; Schmieder, B.; Li, H. Bibcode: 2008A&A...490..315B Altcode: Aims: We performed an analysis of the solar flaring atmosphere above sunspots. During the flare on October 20, 2003 many flaring structures were observed projected onto the sunspots. We analysed the Hα and Ca II line profiles emitted by the ribbons partially overlapping the sunspots. In the penumbra, the line intensity in the far wings is lower than in a typical quiet Sun profile but the core emission of Hα and Ca II lines is typical for flares. We tried to find the structure of the flare observed above the sunspot penumbra using the observations of these chromospheric line profiles.
Methods: NLTE radiative transfer techniques allowed us to model the atmosphere of flaring structures and fit both the synthetic Hα and Ca II line profiles to the observed ones. We have derived semiempirical models of the flaring structure observed above sunspots.
Results: Our analysis shows that the flare emission observed within the sunspot penumbra comes from geometrically thin loop-like structures (cool flare loops) located above the fibrils of the penumbra. The structure of the penumbra located below the flare is almost not affected by the flare i.e. the flare emission in Hα and Ca II comes not from the upper chromosphere but from the structures that are higher in the corona. Therefore, a two-component modelling is necessary to reproduce the flare emission above the sunspot penumbra detected in our observations. Title: Hinode, TRACE, SOHO, and Ground-based Observations of a Quiescent Prominence Authors: Heinzel, P.; Schmieder, B.; Fárník, F.; Schwartz, P.; Labrosse, N.; Kotrč, P.; Anzer, U.; Molodij, G.; Berlicki, A.; DeLuca, E. E.; Golub, L.; Watanabe, T.; Berger, T. Bibcode: 2008ApJ...686.1383H Altcode: A quiescent prominence was observed by several instruments on 2007 April 25. The temporal evolution was recorded in Hα by the Hinode SOT, in X-rays by the Hinode XRT, and in the 195 Å channel by TRACE. Moreover, ground-based observatories (GBOs) provided calibrated Hα intensities. Simultaneous extreme-UV (EUV) data were also taken by the Hinode EIS and SOHO SUMER and CDS instruments. Here we have selected the SOT Hα image taken at 13:19 UT, which nicely shows the prominence fine structure. We compare this image with cotemporaneous ones taken by the XRT and TRACE and show the intensity variations along several cuts parallel to the solar limb. EIS spectra were obtained about half an hour later. Dark prominence structure clearly seen in the TRACE and EIS 195 Å images is due to the prominence absorption in H I, He I, and He II resonance continua plus the coronal emissivity blocking due to the prominence void (cavity). The void clearly visible in the XRT images is entirely due to X-ray emissivity blocking. We use TRACE, EIS, and XRT data to estimate the amount of absorption and blocking. The Hα integrated intensities independently provide us with an estimate of the Hα opacity, which is related to the opacity of resonance continua as follows from the non-LTE radiative-transfer modeling. However, spatial averaging of the Hα and EUV data have quite different natures, which must be taken into account when evaluating the true opacities. We demonstrate this important effect here for the first time. Finally, based on this multiwavelength analysis, we discuss the determination of the column densities and the ionization degree of hydrogen in the prominence. Title: Modelling of the Flare Observed Above Sunspot Penumbra Authors: Berlicki, A.; Heinzel, P.; Schmieder, B.; Li, H. Bibcode: 2008ESPM...12.3.19B Altcode: The solar flaring atmosphere above sunspot observed during the event on October 20, 2003 was analysed. Many flaring structures were visible in projection onto the sunspot penumbra. We analysed the H? and Ca II line profiles emitted by the ribbons partially overlapping the sunspots. These observations were performed with the Multi-channel Infrared Solar Spectrograph (MISS) at Purple Mountain Observatory (PMO, China).

In the sunspot penumbra, the line intensity in far wings is lower than in a typical quiet-Sun profile but in the line centre the intensity of H? and Ca II lines is typical for flares. Using 1D approximation we tried to find the vertical structure of the flare observed above sunspot penumbra using the observations of these chromospheric line profiles.

NLTE radiative transfer techniques allowed us to model the atmosphere of flaring structures and fit both the synthetic H? and Ca II line profiles to the observed ones. We have determined semiempirical models of the flaring structure observed above sunspots.

In our analysis we showed that the flare emission observed within sunspot penumbra comes from geometrically thin loop-like structures located above the fibrils of the penumbra. The structure of the penumbra located below the flare is almost not affected by the flare. The flare emission in chromospheric lines comes not from the upper chromosphere but from the structures located higher in the corona. Therefore, we performed two-component modelling which well reproduce the flare emission above sunspot penumbra. In our model of the flaring layer we included the transition region which is necessary to obtain agreement between the observed and calculated line profiles. Title: Spectrophotometric analysis of Ellerman bombs in the Ca II, Hα, and UV range Authors: Pariat, E.; Schmieder, B.; Berlicki, A.; Deng, Y.; Mein, N.; López Ariste, A.; Wang, S. Bibcode: 2007A&A...473..279P Altcode: Context: Even if Ellerman bombs have been observed in the Hα line within emerging magnetic flux regions since the early 20th century, their origin and the mechanisms that lead to their formation have been strongly debated. Recently, new arguments in favor of chromospheric magnetic reconnection have been advanced. Ellerman bombs seem to be the signature of reconnections that take place during the emergence of the magnetic field.
Aims: We have observed an active region presenting emergence of magnetic flux. We detected and studied Ellerman bombs in two chromospheric lines: Ca ii 8542 Å and Hα. We investigated the link between Ellerman bombs and other structures and phenomena appearing in an emerging active region: UV bright points, arch filament systems, and magnetic topology.
Methods: On August 3, 2004, we performed multi-wavelength observations of the active region NOAA 10655. This active region was the target of SoHO Joint Observation Program 157. Both SoHO/MDI and TRACE (195 Å and 1600 Å) were used. Simultaneously, we observed in the Ca ii and Na D1 lines with the spectro-imager MSDP mode of THEMIS. Alternately to the MSDP, we used the MTR spectropolarimeter on THEMIS to observe in Hα and in the Fe i doublet at 6302 Å. We derived the magnetic field vectors around some Ellerman bombs.
Results: We present the first images of EBs in the Ca ii line and confirm that Ellerman bombs can indeed be observed in the Ca ii line, presenting the same “moustache” geometry profiles as in the Hα line, but with a narrower central absorption in the Ca ii line, in which the peaks of emission are around ±0.35 Å. We noticed that the Ellerman bombs observed in the wings of Ca ii line have an elongated shape - the length about 50% greater than the width. We derived mean semi-axis lengths of 1.4'' × 2.0''. In the UV time profiles of the Ellerman bombs, we noticed successive enhanced emissions. The distribution of lifetimes of these individual impulses presents a strong mode around 210 s. Study of the magnetic topology shows that 9 out of the 13 EBs are located on the inversion line of the longitudinal field and that some typical examples might be associated with a bald patch topology.
Conclusions: We provide new arguments in favor of the reconnection origin of Ellerman bombs. The different individual impulses observed in UV may be related to a bursty mode of reconnection. We also show that this Ca ii 8542 Å chromospheric line is a good indicator of Ellerman bombs and can bring new information about these phenomena. Title: Eruptive and Compact Flares Authors: Schmieder, B.; Aulanier, G.; Delannée, C.; Berlicki, A. Bibcode: 2007AIPC..934...22S Altcode: Solar two ribbon flares are commonly explained by magnetic field reconnections in the high corona. During the reconnection energetic particles (electrons and protons) are accelerated from the reconnection site. These particles are following the magnetic field lines down to the chromosphere. As the plasma density is higher in these lower layers, there are collisions and emission of radiation. Thus after the flare bright ribbons are observed at both ends of loops. These ribbons are typically observed in Hα and in EUV with SoHO and TRACE. As the time is going, these ribbons are expanding away of each other. In most studied models, the reconnection site is an X-point, where two magnetic separatrices intersect. They define four distinct connectivity domains, across which the magnetic connectivity changes discontinuously. In this paper, we present a generalization of this model to 3D complex magnetic topologies where there are no null points, but quasi-separatrices layers instead. In that case, while the ribbons spread away during reconnection, we show that magnetic field lines can quickly slip along them. We propose that this new phenomenon could explain fast extension of Hα and TRACE 1600 Å ribbons, fast moving HXR footpoints as observed by RHESSI, and that it is observed in soft X rays with Hinode/XRT. We also show how this concept can be applied to model the non-wave nature of EIT waves. Title: Spectrophotometry of Ellerman Bombs with THEMIS Authors: Pariat, E.; Schmieder, B.; Berlicki, A.; López Ariste, A. Bibcode: 2007ASPC..368..253P Altcode: During coordinated campaigns with THEMIS and space missions (TRACE, SOHO) emerging flux was observed in multi-wavelengths. Ellerman bombs (EBs) have been identified in TRACE 1600 Å and in chromospheric lines. The Hα and Ca II 8542 Å lines present two enhanced emission peaks respectively at 1 Å and at 0.35 Å which are signatures of EBs. Vector magnetic field measured in the photosphere are consistent with previous results indicating the presence of bald-patches under the EBs and consequently the emergence of horizontal flux tubes from below the photosphere. Title: Observations and Modeling of Line Asymmetries in Chromospheric Flares Authors: Berlicki, A. Bibcode: 2007ASPC..368..387B Altcode: 2007arXiv0704.2436B For many years various asymmetrical profiles of different spectral lines emitted from solar flares have been frequently observed. These asymmetries or line shifts are caused predominantly by vertical mass motions in flaring layers and they provide a good diagnostics for plasma flows during solar flares. There are many controversial results of observations and theoretical analysis of plasma flows in solar chromospheric flares. The main difficulty is the interpretation of line shifts or asymmetries. For many years, methods based on bisector techniques were used but they give a reliable results only for some specific conditions and in most cases cannot be applied. The most promising approach is to use the non-LTE techniques applied for flaring atmosphere. The calculation of synthetic line profiles is performed with the radiative transfer techniques and the assumed physical conditions correspond to flaring atmosphere. I will present an overview of different observations and interpretations of line asymmetries in chromospheric flares. I will explain what we have learnt about the chromospheric evaporation in the frame of hydrodynamical models as well as reconnection models. A critical review will be done on the classical methods used to derive Doppler-shifts for optically thick chomospheric lines. In particular, details on the new approach for interpreting chromospheric line asymmetries based on the non-LTE techniques will be presented. Title: What is the role of magnetic null points in large flares? Authors: Schmieder, B.; Mandrini, C. H.; Démoulin, P.; Aulanier, G.; Li, H.; Berlicki, A. Bibcode: 2007AdSpR..39.1840S Altcode: We have performed the analysis of the magnetic topology of active region NOAA 10486 before two large flares occurring on October 26 and 28, 2003. The 3D extrapolation of the photospheric magnetic field shows the existence of magnetic null points when using two different methods. We use TRACE 1600 Å and 195 Å brightenings as tracers of the energy release due to magnetic reconnections. We conclude on the three following points: The small events observed before the flares are related to low lying null points. They are long lasting and associated with low energy release. They are not triggering the large flares.

On October 26, a high altitude null point is found. We look for bright patches that could correspond to the signatures of coronal reconnection at the null point in TRACE 1600 Å images. However, such bright patches are not observed before the main flare, they are only observed after it.

On October 28, four ribbons are observed in TRACE images before the X17 flare. We interpret them as due to a magnetic breakout reconnection in a quadrupolar configuration. There is no magnetic null point related to these four ribbons, and this reconnection rather occurs at quasi-separatrix layers (QSLs).

We conclude that the existence of a null point in the corona is neither a sufficient nor a necessary condition to give rise to large flares. Title: The Gradual Phase of the X17 Flare on October 28, 2003 Authors: del Zanna, G.; Schmieder, B.; Mason, H.; Berlicki, A.; Bradshaw, S. Bibcode: 2006SoPh..239..173D Altcode: 2006SoPh..239..173Z; 2006SoPh..tmp...74Z We present SOHO/CDS observations taken during the gradual phase of the X17 flare that occurred on October 28, 2003. The CDS data are supplemented with TRACE and ground-based observations. The spectral observations allow us to determine velocities from the Doppler shifts measured in the flare loops and in the two ribbon kernels, one hour and a half after the flare peak. Strong downflows (>70 km s-1) are observed along the loop legs at transition-region temperatures. The velocities are close to those expected for free fall. Observations and results from a hydrodynamic simulation are consistent with the heating taking place for a short time near the top of the arcade. Slight upflows are observed in the outer edges of the ribbons (<60 km s-1) in the EUV lines formed at log T < 6.3. These flows could correspond to the so-called “gentle evaporation.” At “flare” temperatures (Fe xix, log T = 6.9), no appreciable flows are observed. The observations are consistent with the general standard reconnection models for two-ribbons flares. Title: Is Pre-Eruptive Null Point Reconnection Required for Triggering Eruptions? Authors: Li, Hui; Schmieder, Brigitte; Aulanier, Guillaume; Berlicki, Arkadiusz Bibcode: 2006SoPh..237...85L Altcode: 2006SoPh..tmp...22L; 2006SoPh..tmp...18L We study the magnetic field evolution and topology of the active region NOAA 10486 before the 3B/X1.2 flare of October 26, 2003, using observational data from the French-Italian THEMIS telescope, the Michelson Doppler Imager (MDI) onboard Solar and Heliospheric Observatory (SOHO), the Solar Magnetic Field Telescope (SMFT) at Huairou Solar Observation Station (HSOS), and the Transition Region and Coronal Explorer (TRACE). Three dimensional (3D) extrapolation of photospheric magnetic field, assuming a potential field configuration, reveals the existence of two magnetic null points in the corona above the active region. We look at their role in the triggering of the main flare, by using the bright patches observed in TRACE 1600 Å images as tracers at the solar surface of energy release associated with magnetic reconnection at the null points. All the bright patches observed before the flare correspond to the low-altitude null point. They have no direct relationship with the X1.2 flare because the related separatrix is located far from the eruptive site. No bright patch corresponds to the high-altitude null point before the flare. We conclude that eruptions can be triggered without pre-eruptive coronal null point reconnection, and the presence of null points is not a sufficient condition for the occurrence of flares. We propose that this eruptive flare results from the loss of equilibrium due to persistent flux emergence, continuous photospheric motion and strong shear along the magnetic neutral line. The opening of the coronal field lines above the active region should be a byproduct of the large 3B/X1.2 flare rather than its trigger. Title: Magnetic Sources of Flares and CMEs from Multi-Wavelength Flare Studies Authors: Schmieder, B.; Mandrini, C.; Berlicki, A.; Démoulin, P.; Li, H. Bibcode: 2006ESASP.617E.145S Altcode: 2006soho...17E.145S No abstract at ADS Title: Magnetic Sources of flares and CMEs in October 2003 Authors: Schmieder, B.; Démoulin, P.; Berlicki, A.; Mandrini, C.; Hui, Li Bibcode: 2006sf2a.conf..565S Altcode: We present the data analysis of an observing campaign on October 2003 with the objective of understanding the onset of Coronal Mass Ejections (CME) and solar flares. The magnetic field was observed with THEMIS and MDI, the chromosphere with the MSDP operating on THEMIS, the EUV images with SOHO/EIT and TRACE, the X-rays with RHESSI. Two examples of flares will be presented: the 28 Oct 2003 X17 flare and the 20 October 2003 M1.9 flare. The magnetic field analysis of the active regions is done using a linear-force-free field code. The X17 flare is at the origin of a halo CME while the M1.9 flare has no corresponding CME. Before the X17 flare there was a pre-flare event which allowed to change the connectivities in a first phase and to destabilize the stressed field in a second phase producing the X17 flare. A compact twisted emerging flux was responsible of the M1.9 flare, which remains a compact flare due to very tied overlaying loops. These two examples illustrate the major role of the magnetic configuration involved on the flare physical characteristics. Title: A Multi-Wavelength Study of the Compact M1 Flare on October 22, 2002 Authors: Zanna, G. Del; Berlicki, A.; Schmieder, B.; Mason, H. E. Bibcode: 2006SoPh..234...95Z Altcode: In this paper we present a further study of the Ml class flare observed on October 22, 2002. We focus on the SOHO Coronal Diagnostic Spectrometer (CDS) spectral observations performed during a multi-wavelength campaign with TRACE and ground-based instruments (VTT, THEMIS). Strong blue-shifts are observed in the CDS coronal lines in flare kernels during the impulsive phase of this flare. From a careful wavelength calibration we deduce upflows of 140 km/s for the Fe XIX flare emission, with a pattern of progressively smaller flows at lower temperatures. Large line-widths were observed, especially for the Fe XIX line, which indicate the existence of turbulent velocities. The strong upflows correspond to full shifts of the line profiles. These flows are observed at the initial phase of the flare, and correspond to the "explosive evaporation". The regions of the blueshifted kernels, a few arc seconds away from the flare onset location, could be explained by the chain reaction of successive magnetic reconnections of growing emerging field line with higher and higher overlying field. This interpretation is evidenced by the analysis of the magnetic topology of the active region using a linear force-free-field extrapolation of THEMIS magnetograms. Title: A Multi-Wavelength Study of the Compact M1 Flare on October 22, 2002 Authors: del Zanna, G.; Berlicki, A.; Schmieder, B.; Mason, H. E. Bibcode: 2006SoPh..234...95D Altcode: 2006SoPh..234...95Z In this paper we present a further study of the Ml class flare observed on October 22, 2002. We focus on the SOHO Coronal Diagnostic Spectrometer (CDS) spectral observations performed during a multi-wavelength campaign with TRACE and ground-based instruments (VTT, THEMIS). Strong blue-shifts are observed in the CDS coronal lines in flare kernels during the impulsive phase of this flare. From a careful wavelength calibration we deduce upflows of 140 km/s for the Fe XIX flare emission, with a pattern of progressively smaller flows at lower temperatures. Large line-widths were observed, especially for the Fe XIX line, which indicate the existence of turbulent velocities. The strong upflows correspond to full shifts of the line profiles. These flows are observed at the initial phase of the flare, and correspond to the “explosive evaporation”. The regions of the blueshifted kernels, a few arc seconds away from the flare onset location, could be explained by the chain reaction of successive magnetic reconnections of growing emerging field line with higher and higher overlying field. This interpretation is evidenced by the analysis of the magnetic topology of the active region using a linear force-free-field extrapolation of THEMIS magnetograms. Title: Hard X-ray emission at the footpoints of solar flares Authors: Falewicz, R.; Siarkowski, M.; Berlicki, A. Bibcode: 2006AdSpR..38..956F Altcode: We analyse X-ray flare observations made by the Soft X-ray Telescope and Hard X-ray Telescope on the Yohkoh satellite during period 1999 2001. For the strongest flares, when HXT imaging with high time cadence (0.5 1 s) is possible, clear changes in the asymmetry of the observed footpoints fluxes are revealed. We present four examples of flares which illustrate such asymmetrical time variations the best. Observed asymmetries are usually interpreted as due to a difference in magnetic field strength or field divergence at the footpoints, however this interpretation should lead to the existence of strong magnetic field oscillations or movements of the footpoints’ locations in the presence of strong magnetic gradients. Our analysis indicates rather that either differences in the electron injection or electron distribution in each loop’s leg is the source of the observed asymmetry variations. We discuss possible mechanisms which may be responsible for such effect. Title: THEMIS/MSDP magnetic field measurements Authors: Berlicki, A.; Mein, P.; Schmieder, B. Bibcode: 2006A&A...445.1127B Altcode: We present an analysis of longitudinal magnetic field measurements using the spectral data obtained with the French - Italian polarisation free telescope THEMIS working in Multichannel Subtractive Double Pass (MSDP) mode. We also used SOHO/MDI data to extend our analysis. THEMIS observations in the MSDP mode allows us to perform imaging spectropolarimetry characterized by high spatial and time resolution. In our analysis we used the observations of solar active region NOAA 10484 performed on October 20, 2003. From THEMIS 2D spectral images recorded in Na D1 5896 Å line we obtained the longitudinal magnetic field in the active region. The value of the magnetic field was calculated at different distances from the Na D1 line centre. We determine the LOS magnetic field at different heights in the solar atmosphere. SOHO/MDI observations provide the longitudinal magnetic field in Ni I (6768 Å) line. THEMIS/MSDP measurements at Δλ= 0.30 Å are similar to SOHO/MDI results. Gradients of longitudinal magnetic fields derived from MSDP measurements at Δλ= 0.08 and Δλ=0.24 Å exhibit different behaviours according to solar targets. A decrease with height is seen in spot umbrae and penumbrae, while the gradient in facular and network areas suggests a slight increase of the longitudinal magnetic field, which might be explained by the 3D-structure of canopies. Title: Magnetic Topology before a 3B/X1.2 Flare and the Associated CME Authors: Li, H.; Schmieder, B.; Aulanier, G.; Berlicki, A. Bibcode: 2006IAUS..233..399L Altcode: We extrapolated observed photospheric magnetic field before the 3B/X1.2 flare occurred in NOAA 10486 on 2003 October 26. Two magnetic null points exist above the active region, which have no crucial role in triggering the flare, even though enhanced TRACE EUV/UV emission was observed before the main flare due to magnetic reconnection near the lower-altitude null point. We conclude that this flare results from the loss of equilibrium due to persistent flux emergence and photospheric motion, and strong shear. The accompanying fast CME with velocity of ∼ 800 km s^{-1} shows quick mass pickup and energy increase in the low corona. Its kinetic energy is always larger than its potential energy. Title: Small GOES flares with intense hard X-ray emission Authors: Siarkowski, M.; Falewicz, R.; Berlicki, A. Bibcode: 2006AdSpR..38..972S Altcode: Large solar flares with intense soft X-ray emission (i.e., high GOES class) generally tend to show a strong hard X-ray emission. However, there are examples of low GOES class events with unusually strong hard X-ray emission. In this paper, we analyse the morphology and physical parameters of such small GOES intensity flares with strong hard X-ray emission, using Yohkoh SXT images and photometric data obtained from INTERBALL-TAIL RF15-I X-ray Photometer. We observe a great variety in the soft X-ray morphology of such flares (a large diversity of loop configurations). Some of these flares do not differ greatly in their morphology from large intense flares, but most flares are generally compact. In spite of their low intensities in soft X-rays, the significant hard X-ray emission is observed by INTERBALL up to 30 60 keV. We briefly discuss some of the possible causes of the soft and hard X-ray emission ratio of these events. Title: On Line Profile Asymmetries in a Solar Flare Authors: Prosecký, T.; Kotrč, P.; Berlicki, A. Bibcode: 2006CEAB...30...31P Altcode: To detect vertical velocity fields from observed Hα profiles we analyse spectral line profile asymmetries in the flare on August 10, 2003. In addition to a bisector method we use a comparison of the observed and non-LTE calculated profiles. In most of the analysed flare kernels we detect a weak blue asymmetry and interpret it in terms of a downward motion. Capacities and results of the two methods are compared and discussed. Title: Magnetic reconfiguration before the X 17 Solar flare of October 28 2003 Authors: Schmieder, B.; Mandrini, C. H.; Démoulin, P.; Pariat, E.; Berlicki, A.; Deluca, E. Bibcode: 2006AdSpR..37.1313S Altcode: An active region (AR) NOAA 10486, which produced a large number of X-ray flares during October November 2003, was observed during a multi-wavelength campaign with ground based and space instruments. We focus our analysis on the observations of October 28, 2003. The magnetic field was observed with THEMIS (Na D1) and MDI (Ni I), the chromosphere with THEMIS (Ca II 8542 Å) and with the Meudon heliograph in Hα, the EUV images with SOHO/EIT and TRACE. Two pre-events started just before the major X 17 flare. One was related to localized flux emergence and lasted until the decay phase of the X flare; while the second one involved a large scale quadrupolar reconnection, that we infer by modeling the AR magnetic field. Extended dimming areas across the equator (EIT), large arcades of post-flare loops (TRACE 195 Å) and a halo CME (LASCO) were observed consequently after the flare. We perform an extrapolation of the magnetic field above the photosphere using a linear force-free-field approximation that allows us to find the connectivity among the four polarities that would be involved in the quadrupolar reconnection event. The X 17 flare is plausibly due to the destabilisation of a twisted flux tube, the bottom part of this magnetic structure can be visualized by the presence of a filament. The destabilization is caused by converging and shearing photospheric motions towards the main magnetic inversion line. The large scale quadrupolar reconnection related to the second pre-event would favour the opening of the field above the twisted flux tube and, consequently, the coronal mass ejection. Title: Active Region Magnetic Field Observed with Themis/msdp and Soho/mdi Instruments Authors: Berlicki, A.; Mein, P.; Schmieder, B. Bibcode: 2005ESASP.600E..57B Altcode: 2005ESPM...11...57B; 2005dysu.confE..57B No abstract at ADS Title: Multi-Wavelength Analysis of Plasma Flows during Solar Flares Authors: Berlicki, A.; Schmieder, B.; Heinzel, P.; Li, H.; Del Zanna, G.; Rudawy, P. Bibcode: 2005ESASP.600E..58B Altcode: 2005dysu.confE..58B; 2005ESPM...11...58B No abstract at ADS Title: A Multi-Wavelength Study of the 3B/X1.2 Flare Observed on 2003 October 26 Authors: Li, Hui; Li, Jian-Ping; Fang, Cheng; Schmieder, Brigitte; Berlicki, Arkadiusz; Du, Qiu-Sheng Bibcode: 2005ChJAA...5..645L Altcode: We report results from a multi-wavelength study of the 3B/X1.2 two-ribbon disk flare (S15E44), which was well observed by both ground-based and space-borne instruments. Two pairs of conjugate kernels K1 and K4, and K2 and K3 in the Hα images are identified. These kernels are linked by two different systems of EUV loops. K1 and K4 correspond to the two 17 GHz and 34 GHz microwave sources observed by the Nobeyama Radioheliograph (NoRH), while K2 and K3 have no corresponding microwave sources. Optical spectroscopic observations suggest that all the four kernels are possible precipitating sites of non-thermal electrons. Thus the energy of electron deposited in K2 and K3 should be less than 100 keV. Two-dimensional distributions of the full widths at half maximum (FWHM) of the Hα profiles and the line-of-sight (LOS) velocities derived from the Ca II 8542 Å profiles indicate that the largest FWHM and LOS velocity tends to be located near the outer edges of Hα kernels, which is consistent with the scenario of current two-ribbon flare models and previous results. When non-thermal electron bombardment is present, the observed Hα and Ca II 8542 Å profiles are similar to previous observational and theoretical results, while the He I 10830 Å profiles are different from the theoretical ones. This puts some constraints on future theoretical calculation of the He I 10830 Å line. Title: Flows and Heating of the Solar Atmosphere during Solar Flares Authors: Schmieder, B.; Berlicki, A.; Li, H.; Del Zanna, G.; Mason, H. Bibcode: 2005ESASP.592..543S Altcode: 2005soho...16E.102S; 2005ESASP.592E.102S No abstract at ADS Title: Thermal and non-thermal effects driven by magnetic reconnections observed in a confined flare Authors: Li, H.; Berlicki, A.; Schmieder, B. Bibcode: 2005A&A...438..325L Altcode: In order to better understand the energy processes occurring during the impulsive phase of solar flares we compare observations with our magnetic model calculations. We study the 1N/M1.9 confined flare of 20 October 2003 observed during a Joint Observation Program (JOP157), and concentrate on the spectral analysis of the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). These X-ray observations are combined with those from the Solar and Heliospheric Observatory (SOHO) instruments, the French Italian magnetograph (THEMIS), and the Multi-channel Infrared Solar Spectrograph (MISS). The flare occurred in a complex active region, NOAA 10484, with a δ configuration. For model calculations we extrapolate magnetic field lines, which allows us to understand the magnetic topology of the region. This topology and the long impulsive phase of the flare with numerous peaks (GOES, RHESSI) suggest multiple magnetic field reconnection processes. The RHESSI images show a bright structure in hard X-rays (HXR) that could be the tops of the loops. We measure a significant displacement of this structure between the two main maxima of emission, which infers different sites for the reconnection process. The energy release processes can be understood by analyzing the RHESSI spectra using different models. First, using the thermal plus broken power law non-thermal component, we derive the low energy cutoff for the power law distribution of the high-energy electrons (≈25 keV). Then, we apply two models (thermal plus thick-target and thermal plus thin-target non-thermal component) that allow us to fit the observations. These two models lead to similar results; non-thermal energy contributes a significant amount (approximately 20%) of the total flare energy only during the first peak of the impulsive phase. This suggests that the energy that heats the chromosphere is transported mainly by thermal conduction. The temperature of the thermal plasma is 34 MK and 20 MK at the first and second peaks, respectively. Title: Non-LTE diagnostics of velocity fields during the gradual phase of a solar flare Authors: Berlicki, A.; Heinzel, P.; Schmieder, B.; Mein, P.; Mein, N. Bibcode: 2005A&A...430..679B Altcode: We perform an analysis of the velocity field within the Hα ribbons during the gradual phase of an M 1.0 solar flare observed on October 22, 2002. We use spectroscopic observations performed with the German VTT (Vacuum Tower Telescope) working in the MSDP (Multichannel Subtractive Double Pass spectrograph) observing mode. From these observations the Hα line profiles in chosen areas of the flare ribbons were reconstructed and these observational profiles were compared with a grid of synthetic Hα line profiles calculated by the non-LTE radiative-transfer code. This code allows us to calculate different models of the chromosphere with a prescribed velocity field. By optimising the best fit between the observed and synthetic profiles we find the most appropriate models of the chromosphere and vertical structure of the velocity field in the analysed areas of the flare ribbons. By means of the non-LTE radiative-transfer calculations we show that in most analysed areas of the Hα flare ribbons the chromospheric plasma exhibited upward motion with a mean velocity of a few km;s-1. These results are consistent with previous estimates and support the scenario of a gentle evaporation during the gradual phase. Title: Evolution and magnetic topology of the M 1.0 flare of October 22, 2002 Authors: Berlicki, A.; Schmieder, B.; Vilmer, N.; Aulanier, G.; Del Zanna, G. Bibcode: 2004A&A...423.1119B Altcode: In this paper we analyse an M 1.0 confined flare observed mainly during its gradual phase. We use the data taken during a coordinated observational campaign between ground based instruments (THEMIS and VTT) and space observatories (SoHO/CDS and MDI, TRACE and RHESSI). We use these multi-wavelength observations to study the morphology and evolution of the flare, to analyse its gradual phase and to understand the role of various heating mechanisms. During the flare, RHESSI observed emission only within the 3-25 keV spectral range. The RHESSI spectra indicate that the emission of the flare was mainly of thermal origin with a small non-thermal component observed between 10 and 20 keV. Nevertheless, the energy contained in the non-thermal electrons is negligible compared to the thermal energy of the flaring plasma. The temperature of plasma obtained from the fitting of the RHESSI X-ray spectra was between 8.5 and 14 MK. The lower temperature limit is typical for a plasma contained in post flare loops observed in X-rays. Higher temperatures were observed during a secondary peak of emission corresponding to a small impulsive event. The SoHO/CDS observations performed in EUV Fe XIX line also confirm the presence of a hot plasma at temperatures similar to those obtained from RHESSI spectra. The EUV structures were located at the same place as RHESSI X-ray emission. The magnetic topology analysis of the AR coming from a linear force-free field extrapolation explains the observed features of the gradual phase of the flare i.e. the asymmetry of the ribbons and their fast propagation. The combination of the multi-wavelength observations with the magnetic model further suggests that the onset of the flare would be due to the reconnection of an emerging flux in a sheared magnetic configuration. Title: Soft X-ray heating of the solar chromosphere during the gradual phase of two solar flares Authors: Berlicki, A.; Heinzel, P. Bibcode: 2004A&A...420..319B Altcode: In this paper we perform an analysis of the energetics of the solar flaring chromosphere irradiated by soft X-rays (SXR) emitted from overlying hot flare loops. To study an expected SXR heating we used the observations of two solar flares obtained with the Multichannel Subtractive Double Pass (MSDP) spectrograph attached to the Large Coronagraph of the Wrocław University. SXR observations of these flares come from the Yohkoh SXR telescope (SXT). From MSDP spectral images we derived mean Hα line profiles which were then used to construct semi-empirical non-LTE models of the chromosphere in the analyzed areas of flares. On the basis of SXR observations we calculated the mean emission measure EM and the temperature in flaring coronal structures located above the Hα kernels under study and these two quantities were used to compute the SXR irradiation of the chromosphere between 1-300 Å. For each flare model we then evaluated the energy deposit due to such irradiation and compared it with the net radiative cooling rates at all depths in the chromosphere. By means of such modelling we were able to demonstrate that the enhanced emission of selected Hα kernels observed during the gradual phase of these two solar flares cannot be explained in terms of the SXR heating of the chromosphere. We found that radiative losses in all layers of the chromosphere exceeded the amount of the energy deposited by the SXR radiation. However, for stronger flares with much enhanced EM a certain contribution of SXR to the heating cannot be ruled out. Title: Neupert effect in solar flares Authors: Berlicki, A.; Falewicz, R. Bibcode: 2004cosp...35.2204B Altcode: 2004cosp.meet.2204B Tha data obtained with Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) were used to investigate the Neupert effect in a few solar flares. RHESSI is capable to observe the X-ray emission with high time resolution within a very wide energy range (from 3 keV to 17 MeV) and therefore is exceptionally useful to analyse this effect. We used the observations of rather strong events, where the X-ray flux was detected by RHESSI up to high energies. We analysed the time profiles of 'soft' and 'hard' X-ray fluxes observed in diferent energy bands. Our analysis indicates that the time derivatives of X-ray fluxes in low-energy channels are in general agreement with the time profiles of hard X-ray emission observed by RHESSI above 30 keV. The results support the previous analysis of Neupert effect based on the observations obtained with YOHKOH satellite. Title: Multi-wavelength flare study and magnetic configuration Authors: Schmieder, Brigitte; Berlicki, A.; Vilmer, N.; Aulanier, G.; Démoulin, P.; Mein, P.; Mandrini, C.; Deluca, E. Bibcode: 2004IAUS..223..397S Altcode: 2005IAUS..223..397S Recent results of two observation campaigns (October 2002 and October 2003) are presented with the objective of understanding the onset of flares and CMEs. The magnetic field was observed with THEMIS and MDI, the chromosphere with the MSDP operating on the German telescope VTT and on THEMIS, the EUV images with SOHO/CDS and TRACE, the X-ray with RHESSI. We show how important is the magnetic configuration of the active region to produce CMEs using two examples: the October 28 2003 X 17 flare and the October 22 2002 M 1.1 flare. The X 17 flare gave a halo CME while the M 1.1 flare has no corresponding CME. The magnetic topology analysis of the active regions is processed with a linear-force-free field configuration. Title: Small GOES flares with intense hard X-ray emission Authors: Siarkowski, M.; Falewicz, R.; Berlicki, A. Bibcode: 2004cosp...35.3384S Altcode: 2004cosp.meet.3384S During the period of low solar activity numerous flares of GOES class B and early C can be observed. Part of them has quite strong hard X-ray emission (above 20 keV). We are looking for such events using data obtained from BATSE and/or RF15-I X-ray photometer aboard INTERBALL-Tail satellite for the period between January 1994 and November 1998. We analyse morphology and physical parameters of these small flares using the Yohkoh SXT images. Title: Multi-Wavelength Observations of an M1.0 Flare on 22 October 2002 Authors: Berlicki, A.; Schmieder, B.; Vilmer, N.; Mein, P.; Mein, N.; Heinzel, P.; Staiger, J.; Deluca, E. E. Bibcode: 2004IAUS..219..669B Altcode: No abstract at ADS Title: H-alpha spectral observations of the X17+ solar flare on 28 october 2003 Authors: Radziszewski, K.; Rudawy, P.; Schmieder, B.; Berlicki, A. Bibcode: 2004cosp...35.1248R Altcode: 2004cosp.meet.1248R In this paper we present the results of H-alpha observations of the giant X17+ GOES class solar flare on 28 October 2003. The observational data were collected with the Large Coronagraph and MSDP spectrograph of the Astronomical Observatory of Wroclaw University (Poland). During the nearly 3.5 hours of observations we have collected 176 scans covering the whole flaring region (200 000 x 240 000 km2). After the standard data reduction we have obtained quasi-monochromatic 2D images of the flare as well as H-alpha line profiles (+/-0.12 nm) for all pixels of the images. The temporal resolution of our data is equal to about 50 second; the spatial resolution is of the order of 1 second of arc. In this paper we present the main properties of the H-alpha flare: translations of the flare kernels, motion of the matter along the arcade of the H-alpha loops, comparison of the H-alpha structures with ones observed in UV by TRACE and SOHO as well as with magnetograms and numerical models of the magnetic fields and emission of the flaring kernels. Title: Flare evolution and magnetic configuration study Authors: Berlicki, A.; Schmieder, B.; Aulanier, G.; Vilmer, N.; Yan, Y. H. Bibcode: 2004cosp...35.2200B Altcode: 2004cosp.meet.2200B We will present the analysis of M1.0 confined flare emission and evolution in the context of the topology of the coronal magnetic field. This flare was observed in NOAA 0162 on 22 October 2002. The multiwavelength data were taken during a coordinated observational campaign between ground based instruments and space observatories. The photospheric line-of-sight magnetic field observations were obtained with THEMIS and SOHO/MDI. We used these data to perform linear force-free field extrapolation of magnetic field into the corona. Our extrapolation provides an explanation of the appearance of H-alpha flare ribbons. An elongated shape of X-ray emission observed by Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) also follow the predicted shape of extrapolated field lines. Moreover, the X-ray emission observed by RHESSI permit to see thermal emission of coronal loops heated probably by non-thermal electrons, accelerated during the reconnection processes. The presence of non-thermal particles can be deduced from RHESSI X-ray spectra reconstructed during the gradual phase of the flare. On Huairou vector magnetograms of the AR we see that there was strong shear between one of main negative spot and the north small positive spot. The extrapolation with non-constant alpha force-free field model did not obtain any loop to connect these two spots. Title: Hard X-ray emission at the footpoints of solar flares Authors: Falewicz, R.; Siarkowski, M.; Berlicki, A. Bibcode: 2004cosp...35.1257F Altcode: 2004cosp.meet.1257F We analyze hard and soft X-ray observations from the SXT and HXT instruments on the Yohkoh satellite of a few flares of 2000 year. For the strongest events, when the Yohkoh Hard X-ray Telescope imaging with high time cadences (0.5 - 1 sec) is possible, we have revealed clear changes in the asymmetry of the observed footpoints fluxes. We investigate also carefully such characteristics as spectral index variation or footpoints movements during the flare. Observed asymmetry is usually interpreted as an effect of the difference in magnetic field strength or the field divergence at the footpoints. Such traditional interpretation should lead to the existence of strong magnetic field oscillations or movements of the footpoints' locations in the presence of strong magnetic gradient. Our analysis indicates rather the differences in the injection conditions in each loop's leg as a source of the observed asymmetry variations. We analyze few possible mechanisms which may be responsible for observed effect. Title: Soft X-ray Heating of Stellar Chromospheres Authors: Heinzel, P.; Berlicki, A. Bibcode: 2003IAUS..210P.B15H Altcode: No abstract at ADS Title: Soft X-ray heating of the solar chromosphere: gradual phase of a solar flare Authors: Berlicki, A.; Heinzel, P.; Jakimiec, J. Bibcode: 2002ESASP.506..549B Altcode: 2002svco.conf..549B; 2002ESPM...10..549B In this paper we present the analysis of energetics of solar flaring chromosphere heated by soft X-ray radiation coming from overlying hot flare loops. During the solar flare, a large amount of its energy is emitted from hot coronal part in soft X-ray spectral range. This radiation can penetrate into the chromosphere and transmit the energy. This additional heating modifies vertical structure of the chromosphere and it can cause the enhanced emission from some parts of the flare. Therefore, such a mechanism can be responsible for emission of chromospheric flaring structures commonly observed in Hα and other spectral lines during the gradual phases when non-thermal processes are unimportant. To analyze the effect of X-ray heating we used the observations of the solar flare of 25 September 1997. This flare was observed with the Wroclaw Multichannel Subtractive Double Pass spectrograph (MSDP) coupled with the Large Coronagraph. We also use X-ray observations of the flare taken with the SXT telescope. Within the approximation of the quasi steady-state we have calculated the deposit of X-ray energy in the chromosphere. By means of the non-LTE radiative transfer calculations we show that enhanced emission of some H-alpha structures observed during the gradual phase of this solar flare can be partially explained in terms of the soft X-ray heating of the chromosphere by hot 'post-flare' loops seen on the SXT images. We also analyzed the energy budget of X-ray heated flaring chromosphere and found that radiative losses from the chromosphere can be balanced by soft X-ray heating only in some layers of the solar chromosphere. Title: Search for short period coronal plasma oscillations. SECIS results from 1999 and 2001 total eclipses Authors: Rudawy, P.; Phillips, K. J. H.; Read, P.; Gallagher, P. T.; Rompolt, B.; Berlicki, A.; Williams, D.; Keenan, F. P.; Buczylko, A. Bibcode: 2002ESASP.506..967R Altcode: 2002ESPM...10..967R; 2002svco.conf..967R Results of the analysis of the high-cadence observations of the solar corona, taken with the Solar Eclipse Coronal Imaging System instrument during joint British-Polish expeditions during the total solar eclipses of 1999 August 11 in Bulgaria (12768 images) and 2001 June 21 in Zambia (16000 images) are presented. Using data collected during the both solar eclipses we searched for possible periodic changes of the 530.3 nm line intensity emitted by the selected points of the solar corona in the frequency range up to 10 Hz. The time resolution of the collected data is close to 0.05 sec and the pixel size is approximately 4 seconds of arc. The standard photometric processing and correction of the image motions caused by temporal drifts of the instrument pointing were made. Using classical Fourier spectral analysis and wavelet analysis tools we investigated temporal changes of the 530.3 nm coronal line brightness of many thousands of points at various heights and position angles above the solar limb. We did not find any statistically important evidence of periodicity in the frequency range from 1 to 10 Hz in any of the investigated points. Title: Hot plasma motion observed in sigmoidal loop during the flare in NOAA 8323 active region on 4 September 1998 Authors: Berlicki, A.; Rudawy, P.; Siarkowski, M.; Jurecki, M. Bibcode: 2002AdSpR..30..605B Altcode: We present a study of the hot plasma motion in a sigmoidal loop during the C2.2 class solar flare in NOAA 8323 active region on 4 September 1998. In our work we analysed spectra and images taken with Wrocław Large Coronagraph coupled with Multi-Channel Subtractive Double Pass Spectrograph and Hα camera, Yohkoh Soft X-ray Telescope, Yohkoh Bragg Crystal Spectrometer, whole-disk integrated X-ray flux measurements made by GOES and INTERBALL RF15-I photometer as well as radio flux measurements taken with Ondrejov RT3 radiotelescope. The SXT images reveal an expansion of the X-ray flare kernels along the both legs of the sigmoidal loop toward the loop-top. Assuming circular shape of the loop we calculated full velocity vectors of the kernels and their line-of-sight components. The calculated line-of-sight velocities were of the same order as velocities evaluated from BCS spectra. We suppose that observed event was direct manifestation of the plasma evaporation in the flaring loop. Title: Ejection during the solar flare in NOAA 8739 active region on 26 October 1999 Authors: Rudawy, P.; Berlicki, A.; Siarkowski, M.; Kasiniak, K. Bibcode: 2002AdSpR..30..611R Altcode: We analysed a huge ejection of the matter along an extended system of the magnetic loops in NOAA 8739 active region on 26 October 1999. The study was made using high cadence ground-base Multi-Channel Double Pass Spectrograph Hα spectra, TRACE 171 Å and 195 Å ultraviolet, Yohkoh Soft X-ray Telescope images and INTERBALL RF15-I 2-30 keV photometer X-ray measurements. We found the following: The ejection was associated with a C6.5 GOES class solar flare with precursor. The ejection consisted of two distinct stages. The cool matter, visible in Hα line, was ejected at first, after the precursor but before the impulsive phase of the flare. The hotter plasma, visible in UV lines, was ejected two minutes later just before the impulsive phase. The kinetic energy of the ejected Hα matter was relatively low and only a fraction of the matter was transferred to the opposite footpoints of the loop system. The significant part of the matter fell back into the ejection region. A new magnetic field emerged from below the chromosphere in the flaring region just after the ejection. The field was visualised as a co-linear system of the dark loops and fibrils. They then merged with the adjacent filament, extending its length. All flare-like Hα brightenings (with flat or reversed profiles) in the whole active region occurred simultaneously or just after the very distinct increases of the X-ray signal recorded in the 10-15 keV channel. The increases of the signals recorded in the softer channels were much less distinct or did not occur in all. The profiles of the Hα line emitted by the flaring kernels were significantly shifted to the red. Title: Multi-wavelength observations of the flares in NOAA 8307 active region Authors: Siarkowski, M.; Rudawy, P.; Berlicki, A. Bibcode: 2002AdSpR..30..583S Altcode: We analyse in detail a series of four solar flares observed in NOAA 8307 active region on 18 and 19 August 1998 using ground-based Hα and space-based X-ray observations. All the four analysed flares had very similar structure. The observed changes in their morphology and physical properties can be attributed to the gradual changes of the macroscopic magnetic fields of the active region. Title: Interpretation of the MSDP Hα line profiles recorded during the gradual phase of a solar flare Authors: Berlicki, A.; Rudawy, P.; Rompolt, B. Bibcode: 2002AdSpR..30..595B Altcode: In our paper we presented the results of analysis of Hα line profiles emitted by some bright flaring structures observed during the gradual phase of the C7.2 X-ray class flare. The flare was observed in NOAA 8088 active region on 25 September 1997 at 11:50 UT. We have used Hα line spectra obtained with the Wrocław Multichannel Subtractive Double Pass Spectrograph for all the points of the recorded field of view with the temporal resolution of the order of 2 minutes. We analysed the time evolution of the Hα profiles emitted by some selected structures of the flare. We found that during the gradual phase of the flare the Hα spectra exhibited mainly redshifts. The line of sight velocities, corresponding to these shifts, did not exceed +13 km s -1. We found that only few very small areas outside the flare structures showed blueshifted spectra. Hα emission kernels located probably close to X-ray loops footpoints also exhibited redshifted line profiles. In contrast, the modelling made by Antiochos and Sturrock (1978) as well as by Acton et al. (1982) predict the existence of a "gentle evaporation" of plasma heated during the thermal phase of the flares. Such a gentle upward motion of the chromospheric plasma should produce mostly blueshifted profiles of the observed chromospheric spectral lines (Schmieder et al., 1987). Title: Cornoal Heating by MHD Waves: Results from the SECIS Instrument during the 1999 Eclipse Authors: Phillip, K. J. H.; Gallagher, P. T.; Williams, D. R.; Keenan, F. P.; Rudawy, P.; Rompolt, B.; Berlicki, A. Bibcode: 2001IAUS..203..467P Altcode: We report on observational evidence for the rôles that small flare-like events and short-period MHD waves play in the heating of the solar corona. In several studies of SOHO and Yohkoh data, we examine the numbers and energies of small events in the EUV and in soft X-rays can account for the necessary energetics of the quiet-Sun corona, finding that EUV events at least might be sufficient to provide the heating, at least in closed-field regions. Results will be summarized in this paper. However, MHD waves may still play an important part, and in a separate investigation we have used fast-cadence imaging of the white-light and green-line corona during the total eclipse of 1999 August 11 to search for short-period modulations. The imaging system is the Solar Eclipse Coronal Imaging System (SECIS), and consists of a pair of CCD cameras and an adapted PC to form images of the corona at a frame rate of 44 s-1. Preliminary analysis of the data suggests the presence of fast changes over the 2-minute-long period of eclipse totality. This paper will also report on the SECIS data. Title: SECIS: The Solar Eclipse Coronal Eclipse Imaging System Authors: Phillips, K. J. H.; Read, P. D.; Gallagher, P. T.; Keenan, F. P.; Rudawy, P.; Rompolt, B.; Berlicki, A.; Buczylko, A.; Diego, F.; Barnsley, R.; Smartt, R. N.; Pasachoff, J. M.; Babcock, B. A. Bibcode: 2000SoPh..193..259P Altcode: The Solar Eclipse Coronal Imaging System (SECIS) is an instrument designed to search for short-period modulations in the solar corona seen either during a total eclipse or with a coronagraph. The CCD cameras used in SECIS have the capability of imaging the corona at a rate of up to 70 frames a second, with the intensities in each pixel digitised in 12-bit levels. The data are captured and stored on a modified PC. With suitable optics it is thus possible to search for fast changes or short-period wave motions in the corona that will have important implications for the coronal heating mechanism. The equipment has been successfully tested using the Evans Solar Facility coronagraph at National Solar Observatory/Sacramento Peak and during the 11 August 1999 eclipse at a site in north-eastern Bulgaria. The instrument is described and preliminary results are outlined. Title: Hα Spectral and X-ray Observations of the Solar Flare on 2 May 1998 Authors: Berlicki, A.; Falewicz, R.; Rudawy, P. Bibcode: 1999ESASP.448..759B Altcode: 1999ESPM....9..759B; 1999mfsp.conf..759B No abstract at ADS Title: Rotational motion of material in surges Authors: Rompolt, B.; Mińko-Wasiluk, A.; Berlicki, A. Bibcode: 1998PAICz..88..225R Altcode: No abstract at ADS Title: Evidence for prolonged acceleration based on a detailed analysis of the long-duration solar gamma-ray flare of June 15, 1991 Authors: Akimov, V. V.; Ambrož, P.; Belov, A. V.; Berlicki, A.; Chertok, I. M.; Karlický, M.; Kurt, V. G.; Leikov, N. G.; Litvinenko, Yu. E.; Magun, A.; Minko-Wasiluk, A.; Rompolt, B.; Somov, B. V. Bibcode: 1996SoPh..166..107A Altcode: Gamma-ray emission extending to energies greater than 2 GeV and lasting at least for two hours as well as 0.8-8.1 MeV nuclear line emission lasting 40 min were observed with very sensitive telescopes aboard the GAMMA and CGRO satellites for the well-developed post-flare loop formation phase of the 3B/X12 flare on June 15, 1991. We undertook an analysis of optical, radio, cosmic-ray, and other data in order to identify the origin of the energetic particles producing these unusual gamma-ray emissions. The analysis yields evidence that the gamma-rays and other emissions, observed well after the impulsive phase of the flare, appear to be initiated by prolonged nonstationary particle acceleration directly during the late phase of the flare rather than by a long-term trapping of energetic electrons and protons accelerated at the onset of the flare. We argue that such an acceleration, including the acceleration of protons up to GeV energies, can be caused by a prolonged post-eruptive energy release following a coronal mass ejection (CME), when the magnetic field above the active region, strongly disturbed by the CME eruption, relaxes to its initial state through magnetic reconnection in the coronal vertical current sheet.