Author name code: teriaca ADS astronomy entries on 2022-09-14 author:"Teriaca, Luca" ------------------------------------------------------------------------ Title: What drives decayless kink oscillations in active region coronal loops on the Sun? Authors: Mandal, Sudip; Chitta, Lakshmi P.; Antolin, Patrick; Peter, Hardi; Solanki, Sami K.; Auchère, Frédéric; Berghmans, David; Zhukov, Andrei N.; Teriaca, Luca; Cuadrado, Regina A.; Schühle, Udo; Parenti, Susanna; Buchlin, Éric; Harra, Louise; Verbeeck, Cis; Kraaikamp, Emil; Long, David M.; Rodriguez, Luciano; Pelouze, Gabriel; Schwanitz, Conrad; Barczynski, Krzysztof; Smith, Phil J. Bibcode: 2022arXiv220904251M Altcode: We study here the phenomena of decayless kink oscillations in a system of active region (AR) coronal loops. Using high resolution observations from two different instruments, namely the Extreme Ultraviolet Imager (EUI) on board Solar Orbiter and the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory, we follow these AR loops for an hour each on three consecutive days. Our results show significantly more resolved decayless waves in the higher-resolution EUI data compared with the AIA data. Furthermore, the same system of loops exhibits many of these decayless oscillations on Day-2, while on Day-3, we detect very few oscillations and on Day-1, we find none at all. Analysis of photospheric magnetic field data reveals that at most times, these loops were rooted in sunspots, where supergranular flows are generally absent. This suggests that supergranular flows, which are often invoked as drivers of decayless waves, are not necessarily driving such oscillations in our observations. Similarly, our findings also cast doubt on other possible drivers of these waves, such as a transient driver or mode conversion of longitudinal waves near the loop footpoints. In conclusion, through our analysis we find that none of the commonly suspected sources proposed to drive decayless oscillations in active region loops seems to be operating in this event and hence, the search for that elusive wave driver needs to continue. Title: Coronal mass ejection followed by a prominence eruption and a plasma blob as observed by Solar Orbiter Authors: Bemporad, A.; Andretta, V.; Susino, R.; Mancuso, S.; Spadaro, D.; Mierla, M.; Berghmans, D.; D'Huys, E.; Zhukov, A. N.; Talpeanu, D. -C.; Colaninno, R.; Hess, P.; Koza, J.; Jejčič, S.; Heinzel, P.; Antonucci, E.; Da Deppo, V.; Fineschi, S.; Frassati, F.; Jerse, G.; Landini, F.; Naletto, G.; Nicolini, G.; Pancrazzi, M.; Romoli, M.; Sasso, C.; Slemer, A.; Stangalini, M.; Teriaca, L. Bibcode: 2022A&A...665A...7B Altcode: 2022arXiv220210294B Context. On 2021 February 12, two subsequent eruptions occurred above the western limb of the Sun, as seen along the Sun-Earth line. The first event was a typical slow coronal mass ejection (CME), followed ∼7 h later by a smaller and collimated prominence eruption, originating south of the CME, followed by a plasma blob. These events were observed not only by the SOHO and STEREO-A missions, but also by the suite of remote-sensing instruments on board Solar Orbiter.
Aims: We show how data acquired by the Full Sun Imager (FSI), the Metis coronagraph, and the Heliospheric Imager (HI) from the Solar Orbiter perspective can be combined to study the eruptions and different source regions. Moreover, we show how Metis data can be analyzed to provide new information about solar eruptions.
Methods: Different 3D reconstruction methods were applied to the data acquired by different spacecraft, including remote-sensing instruments on board Solar Orbiter. Images acquired by the two Metis channels in the visible light (VL) and H I Ly-α line (UV) were combined to derive physical information about the expanding plasma. The polarization ratio technique was also applied for the first time to Metis images acquired in the VL channel.
Results: The two eruptions were followed in 3D from their source region to their expansion in the intermediate corona. By combining VL and UV Metis data, the formation of a post-CME current sheet (CS) was followed for the first time in the intermediate corona. The plasma temperature gradient across a post-CME blob propagating along the CS was also measured for the first time. Application of the polarization ratio technique to Metis data shows that by combining four different polarization measurements, the errors are reduced by ∼5 − 7%. This constrains the 3D plasma distribution better.

Movies associated to Figs. 4-7 are available at https://www.aanda.org Title: A highly dynamic small-scale jet in a polar coronal hole Authors: Mandal, Sudip; Chitta, Lakshmi Pradeep; Peter, Hardi; Solanki, Sami K.; Cuadrado, Regina Aznar; Teriaca, Luca; Schühle, Udo; Berghmans, David; Auchère, Frédéric Bibcode: 2022A&A...664A..28M Altcode: 2022arXiv220602236M We present an observational study of the plasma dynamics at the base of a solar coronal jet, using high resolution extreme ultraviolet imaging data taken by the Extreme Ultraviolet Imager on board Solar Orbiter, and by the Atmospheric Imaging Assembly on board Solar Dynamics Observatory. We observed multiple plasma ejection events over a period of ∼1 h from a dome-like base that is ca. 4 Mm wide and is embedded in a polar coronal hole. Within the dome below the jet spire, multiple plasma blobs with sizes around 1−2 Mm propagate upwards to the dome apex with speeds of the order of the sound speed (ca. 120 km s−1). Upon reaching the apex, some of these blobs initiate flows with similar speeds towards the other footpoint of the dome. At the same time, high speed super-sonic outflows (∼230 km s−1) are detected along the jet spire. These outflows as well as the intensity near the dome apex appear to be repetitive. Furthermore, during its evolution, the jet undergoes many complex morphological changes, including transitions between the standard and blowout type eruption. These new observational results highlight the underlying complexity of the reconnection process that powers these jets and they also provide insights into the plasma response when subjected to rapid energy injection.

Movies associated to Figs. 1, 2, and 4 are available at https://www.aanda.org 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: Coronal Microjets in Quiet-sun Regions Observed with the Extreme Ultraviolet Imager Onboard Solar Orbiter Authors: Hou, Zhenyong; He, Jiansen; Berghmans, David; Teriaca, Luca; Wang, Linghua; Schuehle, Udo; Tian, Hui; Chen, Yajie; Chen, Hechao; Gao, Yuhang; Bai, Xianyong Bibcode: 2022cosp...44.2536H Altcode: We report the smallest coronal jets ever observed in the quiet Sun with recent high resolution observations from the High Resolution Telescopes (HRI-EUV and HRI-Lyα) of the Extreme Ultraviolet Imager (EUI) onboard Solar Orbiter. In the HRI-EUV (174 Å) images, these microjets usually appear as nearly collimated structures with brightenings at their footpoints. Their average lifetime, projected speed, width, and maximum length are 4.6 min, 62 km $s^{-1}$, 1.0 Mm, and 7.7 Mm, respectively. Inverted-Y shaped structures and moving blobs can be identified in some events. A subset of these events also reveal signatures in the HRI-Lyα (H I Lyα at 1216 Å) images and the extreme ultraviolet images taken by the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory. Our differential emission measure analysis suggests a multi-thermal nature and an average density of ~1.4x10^9 $cm^{-3}$ for these microjets. Their thermal and kinetic energies were estimated to be ~3.9x10$^{24}$ erg and ~2.9x10$^{23}$ erg, respectively, which are of the same order of the released energy predicted by the nanoflare theory. Most events appear to be located at the edges of network lanes and magnetic flux concentrations, suggesting that these coronal microjets are likely generated by magnetic reconnection between small-scale magnetic loops and the adjacent network field. Title: UV coronagraphic observations of an erupting prominence in the H I Ly-alpha line by Metis on-board Solar Orbiter Authors: Russano, Giuliana; Teriaca, Luca; Andretta, Vincenzo; Sasso, Clementina; de Leo, Yara; Uslenghi, Michela Bibcode: 2022cosp...44.2412R Altcode: We show an erupting prominence event occurred on October 25, 2021 above the South-Est limb of the Sun, observed by the Solar Orbiter (SolO) Metis coronagraph UV channel, a narrow-band filter around the H I Ly $\alpha$ line at 121.567 nm. The event, associated to a Coronal Mass Ejection (CME), was visible also in the Metis visible light channel and was also observed by other coronagraphs in orbit around the Sun, like STEREO-A SECCHI COR1 and COR2 and SOHO/LASCO-C2. The observed CME had a projected speed on the order of ∼ 220 km s‑1, as provided by the CACTUS catalog. The event first appears in the STEREO-A EUVI 304 Å images as a typical limb prominence starting at 06:15 UT, then it crossed the fields-of-view (FOVs) of STEREO-A SECCHI COR1 and SOHO/LASCO-C2 (respectively at 8:00 UT and 9:00 UT), until it shows up in the Metis FOV at 14:00 UT where the prominence eruption can be followed as far as ~ 10.2 solar radii. From the Solar Orbiter perspective (very similar to that of SOHO and SDO since the separation angle SolO-Sun-Earth was 5 deg), the source region of the eruption was located just behind the Est limb, as suggested by STEREO-A EUVI 304 Å images (the separation angle STEREO-A-Sun-Earth was ~38 deg), and by the fact that no significant associated signature is seen in the AIA/SDO coronal imagers. This presentation will summarize the ongoing analysis to derive geometrical and physical parameters of the prominence as well as the expanding plasma magnetic field profiles of this interesting event. Title: Automatic detection of small-scale EUV brightenings observed by the Solar Orbiter/EUI Authors: Alipour, N.; Safari, H.; Verbeeck, C.; Berghmans, D.; Auchère, F.; Chitta, L. P.; Antolin, P.; Barczynski, K.; Buchlin, É.; Aznar Cuadrado, R.; Dolla, L.; Georgoulis, M. K.; Gissot, S.; Harra, L.; Katsiyannis, A. C.; Long, D. M.; Mandal, S.; Parenti, S.; Podladchikova, O.; Petrova, E.; Soubrié, É.; Schühle, U.; Schwanitz, C.; Teriaca, L.; West, M. J.; Zhukov, A. N. Bibcode: 2022A&A...663A.128A Altcode: 2022arXiv220404027A Context. Accurate detections of frequent small-scale extreme ultraviolet (EUV) brightenings are essential to the investigation of the physical processes heating the corona.
Aims: We detected small-scale brightenings, termed campfires, using their morphological and intensity structures as observed in coronal EUV imaging observations for statistical analysis.
Methods: We applied a method based on Zernike moments and a support vector machine (SVM) classifier to automatically identify and track campfires observed by Solar Orbiter/Extreme Ultraviolet Imager (EUI) and Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA).
Results: This method detected 8678 campfires (with length scales between 400 km and 4000 km) from a sequence of 50 High Resolution EUV telescope (HRIEUV) 174 Å images. From 21 near co-temporal AIA images covering the same field of view as EUI, we found 1131 campfires, 58% of which were also detected in HRIEUV images. In contrast, about 16% of campfires recognized in HRIEUV were detected by AIA. We obtain a campfire birthrate of 2 × 10−16 m−2 s−1. About 40% of campfires show a duration longer than 5 s, having been observed in at least two HRIEUV images. We find that 27% of campfires were found in coronal bright points and the remaining 73% have occurred out of coronal bright points. We detected 23 EUI campfires with a duration greater than 245 s. We found that about 80% of campfires are formed at supergranular boundaries, and the features with the highest total intensities are generated at network junctions and intense H I Lyman-α emission regions observed by EUI/HRILya. The probability distribution functions for the total intensity, peak intensity, and projected area of campfires follow a power law behavior with absolute indices between 2 and 3. This self-similar behavior is a possible signature of self-organization, or even self-organized criticality, in the campfire formation process.

Supplementary material (S1-S3) is available at https://www.aanda.org Title: The SPICE spectrograph on Solar Orbiter: an introduction and results from the first Orbits Authors: Auchère, Frédéric; Peter, Hardi; Parenti, Susanna; Buchlin, Eric; Thompson, William; Auchere, Frederic; Teriaca, Luca; Kucera, Therese; Carlsson, Mats; Janvier, Miho; Fludra, Andrzej; Giunta, Alessandra; Schuehle, Udo; Hassler, Donald M.; Grundy, Timothy; Sidher, Sunil; Fredvik, Terje; Plowman, Joseph; Aznar Cuadrado, Regina Bibcode: 2022cosp...44.1338A Altcode: The Spectral Imaging of the Coronal Environment (SPICE) instrument is the EUV imaging spectrometer on board the Solar Orbiter mission. With its ability to derive physical properties of the coronal plasma, SPICE is a key component of the payload to establish the connection between the source regions and the in-situ measurements of the solar wind. The spacecraft was successfully launched in February 2020 and completed its cruise phase in December 2021. During this period, the remote sensing instruments were mostly operated during limited periods of time for 'checkout' engineering activities and synoptic observations. Nonetheless, several of these periods provided enough opportunities already to obtain new insights on coronal physics. During the march 2022 perihelion - close to 0.3 AU - SPICE will provide its highest spatial resolution data so far. Coordinated observations between the remote sensing and in-situ instruments will provide the first opportunity to use the full potential of the Solar Orbiter mission. We will review the instrument characteristics and present initial results from the cruise phase and first close encounter. Title: Observation of Magnetic Switchback in the Solar Corona Authors: Telloni, Daniele; Zank, Gary P.; Stangalini, Marco; Downs, Cooper; Liang, Haoming; Nakanotani, Masaru; Andretta, Vincenzo; Antonucci, Ester; Sorriso-Valvo, Luca; Adhikari, Laxman; Zhao, Lingling; Marino, Raffaele; Susino, Roberto; Grimani, Catia; Fabi, Michele; D'Amicis, Raffaella; Perrone, Denise; Bruno, Roberto; Carbone, Francesco; Mancuso, Salvatore; Romoli, Marco; Da Deppo, Vania; Fineschi, Silvano; Heinzel, Petr; Moses, John D.; Naletto, Giampiero; Nicolini, Gianalfredo; Spadaro, Daniele; Teriaca, Luca; Frassati, Federica; Jerse, Giovanna; Landini, Federico; Pancrazzi, Maurizio; Russano, Giuliana; Sasso, Clementina; Berghmans, David; Auchère, Frédéric; Aznar Cuadrado, Regina; Chitta, Lakshmi P.; Harra, Louise; Kraaikamp, Emil; Long, David M.; Mandal, Sudip; Parenti, Susanna; Pelouze, Gabriel; Peter, Hardi; Rodriguez, Luciano; Schühle, Udo; Schwanitz, Conrad; Smith, Phil J.; Verbeeck, Cis; Zhukov, Andrei N. Bibcode: 2022arXiv220603090T Altcode: Switchbacks are sudden, large radial deflections of the solar wind magnetic field, widely revealed in interplanetary space by the Parker Solar Probe. The switchbacks' formation mechanism and sources are still unresolved, although candidate mechanisms include Alfvénic turbulence, shear-driven Kelvin-Helmholtz instabilities, interchange reconnection, and geometrical effects related to the Parker spiral. This Letter presents observations from the Metis coronagraph onboard Solar Orbiter of a single large propagating S-shaped vortex, interpreted as first evidence of a switchback in the solar corona. It originated above an active region with the related loop system bounded by open-field regions to the East and West. Observations, modeling, and theory provide strong arguments in favor of the interchange reconnection origin of switchbacks. Metis measurements suggest that the initiation of the switchback may also be an indicator of the origin of slow solar wind. Title: The magnetic drivers of campfires seen by the Polarimetric and Helioseismic Imager (PHI) on Solar Orbiter Authors: Kahil, F.; Hirzberger, J.; Solanki, S. K.; Chitta, L. P.; Peter, H.; Auchère, F.; Sinjan, J.; Orozco Suárez, D.; Albert, K.; Albelo Jorge, N.; Appourchaux, T.; Alvarez-Herrero, A.; Blanco Rodríguez, J.; Gandorfer, A.; Germerott, D.; Guerrero, L.; Gutiérrez Márquez, P.; Kolleck, M.; del Toro Iniesta, J. C.; Volkmer, R.; Woch, J.; Fiethe, B.; Gómez Cama, J. M.; Pérez-Grande, I.; Sanchis Kilders, E.; Balaguer Jiménez, M.; Bellot Rubio, L. R.; Calchetti, D.; Carmona, M.; Deutsch, W.; Fernández-Rico, G.; Fernández-Medina, A.; García Parejo, P.; Gasent-Blesa, J. L.; Gizon, L.; Grauf, B.; Heerlein, K.; Lagg, A.; Lange, T.; López Jiménez, A.; Maue, T.; Meller, R.; Michalik, H.; Moreno Vacas, A.; Müller, R.; Nakai, E.; Schmidt, W.; Schou, J.; Schühle, U.; Staub, J.; Strecker, H.; Torralbo, I.; Valori, G.; Aznar Cuadrado, R.; Teriaca, L.; Berghmans, D.; Verbeeck, C.; Kraaikamp, E.; Gissot, S. Bibcode: 2022A&A...660A.143K Altcode: 2022arXiv220213859K Context. The Extreme Ultraviolet Imager (EUI) on board the Solar Orbiter (SO) spacecraft observed small extreme ultraviolet (EUV) bursts, termed campfires, that have been proposed to be brightenings near the apexes of low-lying loops in the quiet-Sun atmosphere. The underlying magnetic processes driving these campfires are not understood.
Aims: During the cruise phase of SO and at a distance of 0.523 AU from the Sun, the Polarimetric and Helioseismic Imager on Solar Orbiter (SO/PHI) observed a quiet-Sun region jointly with SO/EUI, offering the possibility to investigate the surface magnetic field dynamics underlying campfires at a spatial resolution of about 380 km.
Methods: We used co-spatial and co-temporal data of the quiet-Sun network at disc centre acquired with the High Resolution Imager of SO/EUI at 17.4 nm (HRIEUV, cadence 2 s) and the High Resolution Telescope of SO/PHI at 617.3 nm (HRT, cadence 2.5 min). Campfires that are within the SO/PHI−SO/EUI common field of view were isolated and categorised according to the underlying magnetic activity.
Results: In 71% of the 38 isolated events, campfires are confined between bipolar magnetic features, which seem to exhibit signatures of magnetic flux cancellation. The flux cancellation occurs either between the two main footpoints, or between one of the footpoints of the loop housing the campfire and a nearby opposite polarity patch. In one particularly clear-cut case, we detected the emergence of a small-scale magnetic loop in the internetwork followed soon afterwards by a campfire brightening adjacent to the location of the linear polarisation signal in the photosphere, that is to say near where the apex of the emerging loop lays. The rest of the events were observed over small scattered magnetic features, which could not be identified as magnetic footpoints of the campfire hosting loops.
Conclusions: The majority of campfires could be driven by magnetic reconnection triggered at the footpoints, similar to the physical processes occurring in the burst-like EUV events discussed in the literature. About a quarter of all analysed campfires, however, are not associated to such magnetic activity in the photosphere, which implies that other heating mechanisms are energising these small-scale EUV brightenings. Title: Stereoscopy of extreme UV quiet Sun brightenings observed by Solar Orbiter/EUI Authors: Zhukov, A. N.; Mierla, M.; Auchère, F.; Gissot, S.; Rodriguez, L.; Soubrié, E.; Thompson, W. T.; Inhester, B.; Nicula, B.; Antolin, P.; Parenti, S.; Buchlin, É.; Barczynski, K.; Verbeeck, C.; Kraaikamp, E.; Smith, P. J.; Stegen, K.; Dolla, L.; Harra, L.; Long, D. M.; Schühle, U.; Podladchikova, O.; Aznar Cuadrado, R.; Teriaca, L.; Haberreiter, M.; Katsiyannis, A. C.; Rochus, P.; Halain, J. -P.; Jacques, L.; Berghmans, D. Bibcode: 2021A&A...656A..35Z Altcode: 2021arXiv210902169Z Context. The three-dimensional fine structure of the solar atmosphere is still not fully understood as most of the available observations are taken from a single vantage point.
Aims: The goal of the paper is to study the three-dimensional distribution of the small-scale brightening events ("campfires") discovered in the extreme-UV quiet Sun by the Extreme Ultraviolet Imager (EUI) aboard Solar Orbiter.
Methods: We used a first commissioning data set acquired by the EUI's High Resolution EUV telescope on 30 May 2020 in the 174 Å passband and we combined it with simultaneous data taken by the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory in a similar 171 Å passband. The two-pixel spatial resolution of the two telescopes is 400 km and 880 km, respectively, which is sufficient to identify the campfires in both data sets. The two spacecraft had an angular separation of around 31.5° (essentially in heliographic longitude), which allowed for the three-dimensional reconstruction of the campfire position. These observations represent the first time that stereoscopy was achieved for brightenings at such a small scale. Manual and automatic triangulation methods were used to characterize the campfire data.
Results: The height of the campfires is located between 1000 km and 5000 km above the photosphere and we find a good agreement between the manual and automatic methods. The internal structure of campfires is mostly unresolved by AIA; however, for a particularly large campfire, we were able to triangulate a few pixels, which are all in a narrow range between 2500 and 4500 km.
Conclusions: We conclude that the low height of EUI campfires suggests that they belong to the previously unresolved fine structure of the transition region and low corona of the quiet Sun. They are probably apexes of small-scale dynamic loops heated internally to coronal temperatures. This work demonstrates that high-resolution stereoscopy of structures in the solar atmosphere has become feasible. Title: Stereoscopy of extreme UV quiet Sun brightenings observed by Solar Orbiter/EUI Authors: Zhukov, Andrei; Mierla, Marilena; Auchere, F.; Gissot, Samuel; Rodriguez, Luciano; Soubrie, Elie; Thompson, William; Inhester, Bernd; Nicula, Bogdan; Antolin, Patrick; Parenti, Susanna; Buchlin, Eric; Barczynski, Krzysztof; Verbeeck, Cis; Kraaikamp, Emil; Smith, Philip; Stegen, Koen; Dolla, Laurent; Harra, Louise; Long, David; Schuhle, Udo; Podladchikova, Olena; Aznar Cuadrado, Regina; Teriaca, Luca; Haberreiter, Margit; Katsiyannis, Athanassios; Rochus, Pierre; Halain, Jean-Philippe; Jacques, Lionel; Berghmans, David Bibcode: 2021AGUFMSH21A..03Z Altcode: We study the three-dimensional distribution of small-scale brightening events (campfires) discovered in the extreme-ultraviolet (EUV) quiet Sun by the EUI telescope onboard the Solar Orbiter mission. We use one of the first commissioning data sets acquired by the HRI_EUV telescope of EUI on 2020 May 30 in the 174 A passband, combined with the simultaneous SDO/AIA dataset taken in the very similar 171 A passband. The spatial resolution of the two telescopes is sufficient to identify the campfires in both datasets. The angular separation between the two spacecraft of around 31.5 degrees allowed for the three-dimensional reconstruction of the position of campfires. This is the first time that stereoscopy was achieved for structures at such a small scale. Manual and automatic triangulation methods were used. The height of campfires is between 1000 km and 5000 km above the photosphere, and there is a good agreement between the results of manual and automatic methods. The internal structure of campfires is mostly not resolved by AIA, but for a large campfire we could triangulate a few pixels, which are all in a narrow height range between 2500 and 4500 km. The low height of campfires suggests that they belong to the previously unresolved fine structure of the transition region and low corona of the quiet Sun. They are probably apexes of small-scale dynamic loops internally heated to coronal temperatures. This work demonstrates that high-resolution stereoscopy of structures in the solar atmosphere has become possible. Title: Propagating brightenings in small loop-like structures in the quiet-Sun corona: Observations from Solar Orbiter/EUI Authors: Mandal, Sudip; Peter, Hardi; Chitta, Lakshmi Pradeep; Solanki, Sami K.; Aznar Cuadrado, Regina; Teriaca, Luca; Schühle, Udo; Berghmans, David; Auchère, Frédéric Bibcode: 2021A&A...656L..16M Altcode: 2021arXiv211108106M Brightenings observed in solar extreme-ultraviolet images are generally interpreted as signatures of micro- or nanoflares occurring in the transition region or at coronal temperatures. Recent observations with the Extreme Ultraviolet Imager (EUI) on board Solar Orbiter have revealed the smallest of such brightenings (called campfires) in the quiet-Sun corona. Analyzing EUI 174 Å data obtained at a resolution of about 400 km on the Sun with a cadence of 5 s on 30 May 2020, we report here a number of cases in which these campfires exhibit propagating signatures along their apparently small (3-5 Mm) loop-like structures. The measured propagation speeds are generally between 25 km s−1 and 60 km s−1. If the loop plasma is assumed to be at a million Kelvin, these apparent motions would be slower than the local sound speed. Furthermore, these brightenings exhibit nontrivial propagation characteristics such as bifurcation, merging, reflection, and repeated plasma ejections. We suggest that these features are manifestations of the internal dynamics of these small-scale magnetic structures and could provide important insights into the dynamic response (∼40 s) of the loop plasma to the heating events and also into the locations of the heating events themselves.

Movies associated to Figs 2-5, A.1, and B.1 are available at https://www.aanda.org 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: Extreme-UV quiet Sun brightenings observed by the Solar Orbiter/EUI Authors: Berghmans, D.; Auchère, F.; Long, D. M.; Soubrié, E.; Mierla, M.; Zhukov, A. N.; Schühle, U.; Antolin, P.; Harra, L.; Parenti, S.; Podladchikova, O.; Aznar Cuadrado, R.; Buchlin, É.; Dolla, L.; Verbeeck, C.; Gissot, S.; Teriaca, L.; Haberreiter, M.; Katsiyannis, A. C.; Rodriguez, L.; Kraaikamp, E.; Smith, P. J.; Stegen, K.; Rochus, P.; Halain, J. P.; Jacques, L.; Thompson, W. T.; Inhester, B. Bibcode: 2021A&A...656L...4B Altcode: 2021arXiv210403382B Context. The heating of the solar corona by small heating events requires an increasing number of such events at progressively smaller scales, with the bulk of the heating occurring at scales that are currently unresolved.
Aims: The goal of this work is to study the smallest brightening events observed in the extreme-UV quiet Sun.
Methods: We used commissioning data taken by the Extreme Ultraviolet Imager (EUI) on board the recently launched Solar Orbiter mission. On 30 May 2020, the EUI was situated at 0.556 AU from the Sun. Its High Resolution EUV telescope (HRIEUV, 17.4 nm passband) reached an exceptionally high two-pixel spatial resolution of 400 km. The size and duration of small-scale structures was determined by the HRIEUV data, while their height was estimated from triangulation with simultaneous images from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory mission. This is the first stereoscopy of small-scale brightenings at high resolution.
Results: We observed small localised brightenings, also known as `campfires', in a quiet Sun region with length scales between 400 km and 4000 km and durations between 10 s and 200 s. The smallest and weakest of these HRIEUV brightenings have not been previously observed. Simultaneous observations from the EUI High-resolution Lyman-α telescope (HRILya) do not show localised brightening events, but the locations of the HRIEUV events clearly correspond to the chromospheric network. Comparisons with simultaneous AIA images shows that most events can also be identified in the 17.1 nm, 19.3 nm, 21.1 nm, and 30.4 nm pass-bands of AIA, although they appear weaker and blurred. Our differential emission measure analysis indicated coronal temperatures peaking at log T ≈ 6.1 − 6.15. We determined the height for a few of these campfires to be between 1000 and 5000 km above the photosphere.
Conclusions: We find that `campfires' are mostly coronal in nature and rooted in the magnetic flux concentrations of the chromospheric network. We interpret these events as a new extension to the flare-microflare-nanoflare family. Given their low height, the EUI `campfires' could stand as a new element of the fine structure of the transition region-low corona, that is, as apexes of small-scale loops that undergo internal heating all the way up to coronal temperatures. Title: Capturing transient plasma flows and jets in the solar corona Authors: Chitta, L. P.; Solanki, S. K.; Peter, H.; Aznar Cuadrado, R.; Teriaca, L.; Schühle, U.; Auchère, F.; Berghmans, D.; Kraaikamp, E.; Gissot, S.; Verbeeck, C. Bibcode: 2021A&A...656L..13C Altcode: 2021arXiv210915106C Intensity bursts in ultraviolet (UV) to X-ray wavelengths and plasma jets are typical signatures of magnetic reconnection and the associated impulsive heating of the solar atmospheric plasma. To gain new insights into the process, high-cadence observations are required to capture the rapid response of plasma to magnetic reconnection as well as the highly dynamic evolution of jets. Here, we report the first 2 s cadence extreme-UV observations recorded by the 174 Å High Resolution Imager of the Extreme Ultraviolet Imager on board the Solar Orbiter mission. These observations, covering a quiet-Sun coronal region, reveal the onset signatures of magnetic reconnection as localized heating events. These localized sources then exhibit repeated plasma eruptions or jet activity. Our observations show that this spatial morphological change from localized sources to jet activity could occur rapidly on timescales of about 20 s. The jets themselves are intermittent and are produced from the source region on timescales of about 20 s. In the initial phases of these events, plasma jets are observed to exhibit speeds, as inferred from propagating intensity disturbances, in the range of 100 km s−1 to 150 km s−1. These jets then propagate to lengths of about 5 Mm. We discuss examples of bidirectional and unidirectional jet activity observed to have been initiated from the initially localized bursts in the corona. The transient nature of coronal bursts and the associated plasma flows or jets along with their dynamics could provide a benchmark for magnetic reconnection models of coronal bursts and jets.

Movies are available at https://www.aanda.org Title: Cosmic-ray flux predictions and observations for and with Metis on board Solar Orbiter Authors: Grimani, C.; Andretta, V.; Chioetto, P.; Da Deppo, V.; Fabi, M.; Gissot, S.; Naletto, G.; Persici, A.; Plainaki, C.; Romoli, M.; Sabbatini, F.; Spadaro, D.; Stangalini, M.; Telloni, D.; Uslenghi, M.; Antonucci, E.; Bemporad, A.; Capobianco, G.; Capuano, G.; Casti, M.; De Leo, Y.; Fineschi, S.; Frassati, F.; Frassetto, F.; Heinzel, P.; Jerse, G.; Landini, F.; Liberatore, A.; Magli, E.; Messerotti, M.; Moses, D.; Nicolini, G.; Pancrazzi, M.; Pelizzo, M. G.; Romano, P.; Sasso, C.; Schühle, U.; Slemer, A.; Straus, T.; Susino, R.; Teriaca, L.; Volpicelli, C. A.; Freiherr von Forstner, J. L.; Zuppella, P. Bibcode: 2021A&A...656A..15G Altcode: 2021arXiv210413700G Context. The Metis coronagraph is one of the remote sensing instruments hosted on board the ESA/NASA Solar Orbiter mission. Metis is devoted to carry out the first simultaneous imaging of the solar corona in both visible light (VL) and ultraviolet (UV). High-energy particles can penetrate spacecraft materials and may limit the performance of the on-board instruments. A study of the galactic cosmic-ray (GCR) tracks observed in the first VL images gathered by Metis during the commissioning phase is presented here. A similar analysis is planned for the UV channel.
Aims: We aim to formulate a prediction of the GCR flux up to hundreds of GeV for the first part of the Solar Orbiter mission to study the performance of the Metis coronagraph.
Methods: The GCR model predictions are compared to observations gathered on board Solar Orbiter by the High-Energy Telescope in the range between 10 MeV and 100 MeV in the summer of 2020 as well as with the previous measurements. Estimated cosmic-ray fluxes above 70 MeV n−1 have been also parameterized and used for Monte Carlo simulations aimed at reproducing the cosmic-ray track observations in the Metis coronagraph VL images. The same parameterizations can also be used to study the performance of other detectors.
Results: By comparing observations of cosmic-ray tracks in the Metis VL images with FLUKA Monte Carlo simulations of cosmic-ray interactions in the VL detector, we find that cosmic rays fire only a fraction, on the order of 10−4, of the whole image pixel sample. We also find that the overall efficiency for cosmic-ray identification in the Metis VL images is approximately equal to the contribution of Z ≥ 2 GCR particles. A similar study will be carried out during the whole of the Solar Orbiter's mission duration for the purposes of instrument diagnostics and to verify whether the Metis data and Monte Carlo simulations would allow for a long-term monitoring of the GCR proton flux. Title: First observations from the SPICE EUV spectrometer on Solar Orbiter Authors: Fludra, A.; Caldwell, M.; Giunta, A.; Grundy, T.; Guest, S.; Leeks, S.; Sidher, S.; Auchère, F.; Carlsson, M.; Hassler, D.; Peter, H.; Aznar Cuadrado, R.; Buchlin, É.; Caminade, S.; DeForest, C.; Fredvik, T.; Haberreiter, M.; Harra, L.; Janvier, M.; Kucera, T.; Müller, D.; Parenti, S.; Schmutz, W.; Schühle, U.; Solanki, S. K.; Teriaca, L.; Thompson, W. T.; Tustain, S.; Williams, D.; Young, P. R.; Chitta, L. P. Bibcode: 2021A&A...656A..38F Altcode: 2021arXiv211011252F
Aims: We present first science observations taken during the commissioning activities of the Spectral Imaging of the Coronal Environment (SPICE) instrument on the ESA/NASA Solar Orbiter mission. SPICE is a high-resolution imaging spectrometer operating at extreme ultraviolet (EUV) wavelengths. In this paper we illustrate the possible types of observations to give prospective users a better understanding of the science capabilities of SPICE.
Methods: We have reviewed the data obtained by SPICE between April and June 2020 and selected representative results obtained with different slits and a range of exposure times between 5 s and 180 s. Standard instrumental corrections have been applied to the raw data.
Results: The paper discusses the first observations of the Sun on different targets and presents an example of the full spectra from the quiet Sun, identifying over 40 spectral lines from neutral hydrogen and ions of carbon, oxygen, nitrogen, neon, sulphur, magnesium, and iron. These lines cover the temperature range between 20 000 K and 1 million K (10 MK in flares), providing slices of the Sun's atmosphere in narrow temperature intervals. We provide a list of count rates for the 23 brightest spectral lines. We show examples of raster images of the quiet Sun in several strong transition region lines, where we have found unusually bright, compact structures in the quiet Sun network, with extreme intensities up to 25 times greater than the average intensity across the image. The lifetimes of these structures can exceed 2.5 hours. We identify them as a transition region signature of coronal bright points and compare their areas and intensity enhancements. We also show the first above-limb measurements with SPICE above the polar limb in C III, O VI, and Ne VIII lines, and far off limb measurements in the equatorial plane in Mg IX, Ne VIII, and O VI lines. We discuss the potential to use abundance diagnostics methods to study the variability of the elemental composition that can be compared with in situ measurements to help confirm the magnetic connection between the spacecraft location and the Sun's surface, and locate the sources of the solar wind.
Conclusions: The SPICE instrument successfully performs measurements of EUV spectra and raster images that will make vital contributions to the scientific success of the Solar Orbiter mission. 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: Exploring the Solar Wind from Its Source on the Corona into the Inner Heliosphere during the First Solar Orbiter-Parker Solar Probe Quadrature Authors: Telloni, Daniele; Andretta, Vincenzo; Antonucci, Ester; Bemporad, Alessandro; Capuano, Giuseppe E.; Fineschi, Silvano; Giordano, Silvio; Habbal, Shadia; Perrone, Denise; Pinto, Rui F.; Sorriso-Valvo, Luca; Spadaro, Daniele; Susino, Roberto; Woodham, Lloyd D.; Zank, Gary P.; Romoli, Marco; Bale, Stuart D.; Kasper, Justin C.; Auchère, Frédéric; Bruno, Roberto; Capobianco, Gerardo; Case, Anthony W.; Casini, Chiara; Casti, Marta; Chioetto, Paolo; Corso, Alain J.; Da Deppo, Vania; De Leo, Yara; Dudok de Wit, Thierry; Frassati, Federica; Frassetto, Fabio; Goetz, Keith; Guglielmino, Salvo L.; Harvey, Peter R.; Heinzel, Petr; Jerse, Giovanna; Korreck, Kelly E.; Landini, Federico; Larson, Davin; Liberatore, Alessandro; Livi, Roberto; MacDowall, Robert J.; Magli, Enrico; Malaspina, David M.; Massone, Giuseppe; Messerotti, Mauro; Moses, John D.; Naletto, Giampiero; Nicolini, Gianalfredo; Nisticò, Giuseppe; Panasenco, Olga; Pancrazzi, Maurizio; Pelizzo, Maria G.; Pulupa, Marc; Reale, Fabio; Romano, Paolo; Sasso, Clementina; Schühle, Udo; Stangalini, Marco; Stevens, Michael L.; Strachan, Leonard; Straus, Thomas; Teriaca, Luca; Uslenghi, Michela; Velli, Marco; Verscharen, Daniel; Volpicelli, Cosimo A.; Whittlesey, Phyllis; Zangrilli, Luca; Zimbardo, Gaetano; Zuppella, Paola Bibcode: 2021ApJ...920L..14T Altcode: 2021arXiv211011031T This Letter addresses the first Solar Orbiter (SO)-Parker Solar Probe (PSP) quadrature, occurring on 2021 January 18 to investigate the evolution of solar wind from the extended corona to the inner heliosphere. Assuming ballistic propagation, the same plasma volume observed remotely in the corona at altitudes between 3.5 and 6.3 solar radii above the solar limb with the Metis coronagraph on SO can be tracked to PSP, orbiting at 0.1 au, thus allowing the local properties of the solar wind to be linked to the coronal source region from where it originated. Thanks to the close approach of PSP to the Sun and the simultaneous Metis observation of the solar corona, the flow-aligned magnetic field and the bulk kinetic energy flux density can be empirically inferred along the coronal current sheet with an unprecedented accuracy, allowing in particular estimation of the Alfvén radius at 8.7 solar radii during the time of this event. This is thus the very first study of the same solar wind plasma as it expands from the sub-Alfvénic solar corona to just above the Alfvén surface. Title: Multipoint remote and in situ observations of interplanetary coronal mass ejection structures during 2011 and associated geomagnetic storms Authors: Mishra, Wageesh; Dave, Kunjal; Srivastava, Nandita; Teriaca, Luca Bibcode: 2021MNRAS.506.1186M Altcode: We present multipoint remote and in situ observations of interplanetary coronal mass ejection (ICME) structures during the year 2011. The selected ICMEs arrived at Earth on 2011 March 11 and 2011 August 6, and led to geomagnetic storms. Around the launch of these CMEs from the Sun, the coronagraphs onboard STEREO-Aand-B and SOHO enabled the CMEs to be imaged from three longitudinally separated viewpoints. We attempt to identify the in situ plasma and magnetic parameters of the ICME structures at multiple locations, for example at both STEREO spacecraft and also at the ACE/Wind spacecraft near the first Sun-Earth Lagrangian point (L1), to investigate the global configuration, interplanetary propagation, arrival times and geomagnetic response of the ICMEs. The near-Earth identified ICMEs of March 11 and August 6 formed as a result of the interaction of two successive CMEs observed in the inner corona on March 7 (for the March 11 ICME) and on August 3-4 (for the August 6 ICME). Our study suggests that the structures associated with interacting CMEs, possibly as a result of deflection or large sizes, may reach to even larger longitudinally separated locations in the heliosphere. Our multipoint in situ analysis shows that the characteristics of the same shock, propagating in a pre-conditioned medium, may be different at different longitudinal locations in the heliosphere. Similarly, multiple cuts through the same ejecta/complex ejecta, formed as a result of CME-CME interaction, are found to have inhomogeneous properties. The study highlights the difficulties in connecting the local observations of an ICME from a single in situ spacecraft to its global structures. Title: Coronal Microjets in Quiet-Sun Regions Observed with the Extreme Ultraviolet Imager on Board the Solar Orbiter Authors: Hou, Zhenyong; Tian, Hui; Berghmans, David; Chen, Hechao; Teriaca, Luca; Schühle, Udo; Gao, Yuhang; Chen, Yajie; He, Jiansen; Wang, Linghua; Bai, Xianyong Bibcode: 2021ApJ...918L..20H Altcode: 2021arXiv210808718H We report the smallest coronal jets ever observed in the quiet Sun with recent high-resolution observations from the High Resolution Telescopes (HRIEUV and HRILyα) of the Extreme Ultraviolet Imager on board the Solar Orbiter (SO). In the HRIEUV (174 Å) images, these microjets usually appear as nearly collimated structures with brightenings at their footpoints. Their average lifetime, projected speed, width, and maximum length are 4.6 minutes, 62 km s-1, 1.0 Mm, and 7.7 Mm, respectively. Inverted-Y shaped structures and moving blobs can be identified in some events. A subset of these events also reveal signatures in the HRILyα (H I Lyα at 1216 Å) images and the extreme ultraviolet images taken by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). Our differential emission-measure (EM) analysis suggests a multithermal nature and an average density of ~1.4 × 109 cm-3 for these microjets. Their thermal and kinetic energies were estimated to be ~3.9 × 1024 erg and ~2.9 × 1023 erg, respectively, which are of the same order of the released energy predicted by the nanoflare theory. Most events appear to be located at the edges of network lanes and magnetic flux concentrations, suggesting that these coronal microjets are likely generated by magnetic reconnection between small-scale magnetic loops and the adjacent network field. Title: Magnetic imaging of the outer solar atmosphere (MImOSA) Authors: Peter, H.; Ballester, E. Alsina; Andretta, V.; Auchère, F.; Belluzzi, L.; Bemporad, A.; Berghmans, D.; Buchlin, E.; Calcines, A.; Chitta, L. P.; Dalmasse, K.; Alemán, T. del Pino; Feller, A.; Froment, C.; Harrison, R.; Janvier, M.; Matthews, S.; Parenti, S.; Przybylski, D.; Solanki, S. K.; Štěpán, J.; Teriaca, L.; Bueno, J. Trujillo Bibcode: 2021ExA...tmp...95P Altcode: The magnetic activity of the Sun directly impacts the Earth and human life. Likewise, other stars will have an impact on the habitability of planets orbiting these host stars. Although the magnetic field at the surface of the Sun is reasonably well characterised by observations, the information on the magnetic field in the higher atmospheric layers is mainly indirect. This lack of information hampers our progress in understanding solar magnetic activity. Overcoming this limitation would allow us to address four paramount long-standing questions: (1) How does the magnetic field couple the different layers of the atmosphere, and how does it transport energy? (2) How does the magnetic field structure, drive and interact with the plasma in the chromosphere and upper atmosphere? (3) How does the magnetic field destabilise the outer solar atmosphere and thus affect the interplanetary environment? (4) How do magnetic processes accelerate particles to high energies? New ground-breaking observations are needed to address these science questions. We suggest a suite of three instruments that far exceed current capabilities in terms of spatial resolution, light-gathering power, and polarimetric performance: (a) A large-aperture UV-to-IR telescope of the 1-3 m class aimed mainly to measure the magnetic field in the chromosphere by combining high spatial resolution and high sensitivity. (b) An extreme-UV-to-IR coronagraph that is designed to measure the large-scale magnetic field in the corona with an aperture of about 40 cm. (c) An extreme-UV imaging polarimeter based on a 30 cm telescope that combines high throughput in the extreme UV with polarimetry to connect the magnetic measurements of the other two instruments. Placed in a near-Earth orbit, the data downlink would be maximised, while a location at L4 or L5 would provide stereoscopic observations of the Sun in combination with Earth-based observatories. This mission to measure the magnetic field will finally unlock the driver of the dynamics in the outer solar atmosphere and thereby will greatly advance our understanding of the Sun and the heliosphere. Title: In-flight optical performance assessment for the Metis solar coronagraph Authors: Da Deppo, Vania; Chioetto, Paolo; Andretta, Vincenzo; Casini, Chiara; Frassetto, Fabio; Slemer, Alessandra; Zuppella, Paola; Romoli, Marco; Fineschi, Silvano; Heinzel, Petr; Naletto, Giampiero; Nicolini, Gianalfredo; Spadaro, Daniele; Stangalini, Marco; Teriaca, Luca; Bemporad, Alessandro; Casti, Marta; Fabi, Michele; Grimani, Catia; Heerlein, Klaus; Jerse, Giovanna; Landini, Federico; Liberatore, Alessandro; Magli, Enrico; Melich, Radek; Pancrazzi, Maurizio; Pelizzo, Maria-G.; Romano, Paolo; Sasso, Clementina; Straus, Thomas; Susino, Roberto; Uslenghi, Michela; Volpicelli, Cosimo Antonio Bibcode: 2021SPIE11852E..10D Altcode: Metis is a multi-wavelength coronagraph onboard the European Space Agency (ESA) Solar Orbiter mission. The instrument features an innovative instrument design conceived for simultaneously imaging the Sun's corona in the visible and ultraviolet range. The Metis visible channel employs broad-band, polarized imaging of the visible K-corona, while the UV one uses narrow-band imaging at the HI Ly 􀄮, i.e. 121.6 nm. During the commissioning different acquisitions and activities, performed with both the Metis channels, have been carried out with the aim to check the functioning and the performance of the instrument. In particular, specific observations of stars have been devised to assess the optical alignment of the telescope and to derive the instrument optical parameters such as focal length, PSF and possibly check the optical distortion and the vignetting function. In this paper, the preliminary results obtained for the PSF of both channels and the determination of the scale for the visible channel will be described and discussed. The in-flight obtained data will be compared to those obtained on-ground during the calibration campaign. Title: On-ground flat-field calibration of the Metis coronagraph onboard the Solar Orbiter ESA mission Authors: Casini, C.; Da Deppo, V.; Zuppella, P.; Chioetto, P.; Slemer, A.; Frassetto, F.; Romoli, M.; Landini, F.; Pancrazzi, M.; Andretta, V.; De Leo, Y.; Bemporad, A.; Fabi, M.; Fineschi, S.; Frassati, F.; Grimani, C.; Jerse, G.; Heerlein, K.; Liberatore, A.; Magli, E.; Naletto, G.; Nicolini, G.; Pelizzo, M. G.; Romano, P.; Sasso, C.; Spadaro, D.; Stangalini, M.; Straus, T.; Susino, R.; Teriaca, L.; Uslenghi, M.; Casti, M.; Heinzel, P.; Volpicelli, A. Bibcode: 2021SPIE11852E..5BC Altcode: Solar Orbiter, launched on February 9th 2020, is an ESA/NASA mission conceived to study the Sun. This work presents the embedded Metis coronagraph and its on-ground calibration in the 580-640 nm wavelength range using a flat field panel. It provides a uniform illumination to evaluate the response of each pixel of the detector; and to characterize the Field of View (FoV) of the coronagraph. Different images with different exposure times were acquired during the on-ground calibration campaign. They were analyzed to verify the linearity response of the instrument and the requirements for the FoV: the maximum area of the sky that Metis can acquire. Title: Challenges during Metis-Solar Orbiter commissioning phase Authors: Romoli, Marco; Andretta, Vincenzo; Bemporad, Alessandro; Casti, Marta; Da Deppo, Vania; De Leo, Yara; Fabi, Michele; Fineschi, Silvano; Frassetto, Fabio; Grimani, Catia; Heerlein, Klaus; Heinzel, Petr; Jerse, Giovanna; Landini, Federico; Liberatore, Alessandro; Magli, Enrico; Naletto, Giampiero; Nicolini, Gianalfredo; Pancrazzi, Maurizio; Pelizzo, Maria Guglielmina; Romano, Paolo; Sasso, Clementina; Schühle, Udo; Slemer, Alessandra; Spadaro, Daniele; Straus, Thomas; Susino, Roberto; Teriaca, Luca; Uslenghi, Michela; Volpicelli, Cosimo Antonio; Zupella, Paola Bibcode: 2021SPIE11852E..5AR Altcode: Metis is the visible light and UV light imaging coronagraph on board the ESA-NASA mission Solar Orbiter that has been launched February 10th, 2020, from Cape Canaveral. Scope of the mission is to study the Sun up close, taking high-resolution images of the Sun's poles for the first time, and understanding the Sun-Earth connection. Metis coronagraph will image the solar corona in the linearly polarized broadband visible radiation and in the UV HI Ly-α line from 1.6 to 3 solar radii when at Solar Orbiter perihelion, providing a diagnostics, with unprecedented temporal coverage and spatial resolution, of the structures and dynamics of the full corona. Solar Orbiter commissioning phase big challenge was Covid-19 social distancing phase that affected the way commissioning of a spacecraft and its payload is typically done. Metis coronagraph on-board Solar Orbiter had its additional challenges: to wake up and check the performance of the optical, electrical and thermal subsystems, most of them unchecked since Metis delivery to spacecraft prime, Airbus, in May 2017. The roadmap to the fully commissioned coronagraph is here described throughout the steps from the software functional test, the switch on of the detectors of the two channels, UV and visible, to the optimization of the occulting system and the characterization of the instrumental stray light, one of the most challenging features in a coronagraph. Title: In-flight calibration of Metis coronagraph on board of Solar Orbiter Authors: Liberatore, A.; Fineschi, S.; Casti, M.; Capobianco, G.; Romoli, M.; Andretta, V.; Bemporad, A.; Da Deppo, V.; De Leo, Y.; Fabi, M.; Frassetto, F.; Grimani, C.; Heerlein, K.; Heinzel, P.; Jerse, G.; Landini, F.; Magli, E.; Naletto, G.; Nicolini, G.; Pancrazzi, M.; Pelizzo, M. G.; Romano, P.; Sasso, C.; Slemer, A.; Spadaro, D.; Straus, T.; Susino, R.; Teriaca, L.; Uslenghi, M.; Volpicelli, C. A.; Zuppella, P. Bibcode: 2021SPIE11852E..48L Altcode: Metis coronagraph is one of the remote-sensing instruments of the Solar Orbiter mission launched at the begin of 2020. The mission profile will allow for the first time the remote-sensing observation of the Sun from a very close distance and increasing the latitude with respect to the ecliptic plane. In particular, Metis is aimed at the overall characterization and study of the solar corona and solar wind. Metis instrument acquires images of the solar corona in two different wavelengths simultaneously; ultraviolet (UV) and visible-light (VL). The VL channel includes a polarimeter with an electro-optically modulating Liquid Crystal Variable Retarder (LCVR) to measure the linearly polarized brighness pB) of the K-corona. This paper presents part of the in-flight calibration results for both wavelength channels together with a comparison with on-ground calibrations. The orientation of the K-corona linear polarization was used for the in-flight calibration of the Metis polarimeter. This paper describes the correction of the on-ground VL vignetting function after the in-flight adjustment of the internal occulter. The same vignetting function was adaptated to the UV channel. Title: First results from combined EUI and SPICE observations of Lyman lines of Hydrogen and He II Authors: Teriaca, Luca Bibcode: 2021EGUGA..2314801T Altcode: The Solar Orbiter spacecraft carries a powerful set of remote sensing instruments that allow studying the solar atmosphere with unprecedented diagnostic capabilities. Many such diagnostics require the simultaneous usage of more than one instrument. One example of that is the capability, for the first time, to obtain (near) simultaneous spatially resolved observations of the emission from the first three lines of the Lyman series of hydrogen and of He II Lyman alpha. In fact, the SPectral Imaging of the Coronal Environment (SPICE) spectrometer can observe the Lyman beta and gamma lines in its long wavelength (SPICE-LW) channel, the High Resolution Lyman Alpha (HRILYA) telescope of the Extreme Ultraviolet Imager (EUI) acquires narrow band images in the Lyman alpha line while the Full Disk Imager (FSI) of EUI can take images dominated by the Lyman alpha line of ionized Helium at 30.4 nm (FSI-304). Being hydrogen and helium the main components of our star, these very bright transitions play an important role in the energy budget of the outer atmosphere via radiative losses and the measurement of their profiles and radiance ratios is a fundamental constraint to any comprehensive modelization effort of the upper solar chromosphere and transition region. Additionally, monitoring their average ratios can serve as a check out for the relative radiometric performance of the two instruments throughout the mission.Although the engineering data acquired so far are far from ideal in terms of time simultaneity (often only within about 1 h) and line coverage (often only Lyman beta was acquired by SPICE and not always near simultaneous images from all three telescopes are available) the analysis we present here still offers a great opportunity to have a first look at the potential of this diagnostic from the two instruments.In fact, we have identified a series of datasets obtained at disk center and at various positions at the solar limb that allow studying the Lyman alpha to beta radiance ratio and their relation to He II 30.4 as a function of the position on the Sun (disk center versus limb and quiet Sun versus coronal holes). Title: Magnetic Imaging of the Outer Solar Atmosphere (MImOSA): Unlocking the driver of the dynamics in the upper solar atmosphere Authors: Peter, H.; Alsina Ballester, E.; Andretta, V.; Auchere, F.; Belluzzi, L.; Bemporad, A.; Berghmans, D.; Buchlin, E.; Calcines, A.; Chitta, L. P.; Dalmasse, K.; del Pino Aleman, T.; Feller, A.; Froment, C.; Harrison, R.; Janvier, M.; Matthews, S.; Parenti, S.; Przybylski, D.; Solanki, S. K.; Stepan, J.; Teriaca, L.; Trujillo Bueno, J. Bibcode: 2021arXiv210101566P Altcode: The magnetic activity of the Sun directly impacts the Earth and human life. Likewise, other stars will have an impact on the habitability of planets orbiting these host stars. The lack of information on the magnetic field in the higher atmospheric layers hampers our progress in understanding solar magnetic activity. Overcoming this limitation would allow us to address four paramount long-standing questions: (1) How does the magnetic field couple the different layers of the atmosphere, and how does it transport energy? (2) How does the magnetic field structure, drive and interact with the plasma in the chromosphere and upper atmosphere? (3) How does the magnetic field destabilise the outer solar atmosphere and thus affect the interplanetary environment? (4) How do magnetic processes accelerate particles to high energies? New ground-breaking observations are needed to address these science questions. We suggest a suite of three instruments that far exceed current capabilities in terms of spatial resolution, light-gathering power, and polarimetric performance: (a) A large-aperture UV-to-IR telescope of the 1-3 m class aimed mainly to measure the magnetic field in the chromosphere by combining high spatial resolution and high sensitivity. (b) An extreme-UV-to-IR coronagraph that is designed to measure the large-scale magnetic field in the corona with an aperture of about 40 cm. (c) An extreme-UV imaging polarimeter based on a 30 cm telescope that combines high throughput in the extreme UV with polarimetry to connect the magnetic measurements of the other two instruments. This mission to measure the magnetic field will unlock the driver of the dynamics in the outer solar atmosphere and thereby greatly advance our understanding of the Sun and the heliosphere. Title: Relative coronal abundance diagnostics with Solar Orbiter/SPICE Authors: Zambrana Prado, N.; Buchlin, E.; Peter, H.; Young, P. R.; Auchere, F.; Carlsson, M.; Fludra, A.; Hassler, D.; Aznar Cuadrado, R.; Caminade, S.; Caldwell, M.; DeForest, C.; Fredvik, T.; Harra, L.; Janvier, M.; Kucera, T. A.; Giunta, A. S.; Grundy, T.; Müller, D.; Parenti, S.; Schmutz, W. K.; Schühle, U.; Sidher, S.; Teriaca, L.; Thompson, W. T.; Williams, D. Bibcode: 2020AGUFMSH038..09Z Altcode: Linking solar activity on the surface and in the corona to the inner heliosphere is one of Solar Orbiter's main goals. Its UV spectrometer SPICE (SPectral Imaging of the Coronal Environment) will provide relative abundance measurements which will be key in this quest as different structures on the Sun have different abundances as a consequence of the FIP (First Ionization Potential) effect. Solar Orbiter's unique combination of remote sensing and in-situ instruments coupled with observation from other missions such as Parker Solar Probe will allow us to compare in-situ and remote sensing composition data. With the addition of modeling, these new results will allow us to trace back the source of heliospheric plasma. As high telemetry will not always be available with SPICE, we have developed a method for measuring relative abundances that is both telemetry efficient and reliable. Unlike methods based on Differential Emission Measure (DEM) inversion, the Linear Combination Ratio (LCR) method does not require a large number of spectral lines. This new method is based on linear combinations of UV spectral lines. The coefficients of the combinations are optimized such that the ratio of two linear combinations of radiances would yield the relative abundance of two elements. We present some abundance diagnostics tested on different combinations of spectral lines observable by SPICE. Title: Dynamics and thermal structure in the quiet Sun seen by SPICE Authors: Peter, H.; Aznar Cuadrado, R.; Schühle, U.; Teriaca, L.; Auchere, F.; Carlsson, M.; Fludra, A.; Hassler, D.; Buchlin, E.; Caminade, S.; Caldwell, M.; DeForest, C.; Fredvik, T.; Harra, L. K.; Janvier, M.; Kucera, T. A.; Giunta, A. S.; Grundy, T.; Müller, D.; Parenti, S.; Schmutz, W. K.; Sidher, S.; Thompson, W. T.; Williams, D.; Young, P. R. Bibcode: 2020AGUFMSH038..03P Altcode: We will present some of the early data of the Spectral Imaging of the Coronal Environment (SPICE) instrument on Solar Orbiter. One of the unique features of SPICE is its capability to record a wide range of wavelengths in the extreme UV with the possibility to record spectral lines giving access to a continuous plasma temperature range from 10.000 K to well above 1 MK. The data taken so far were for commissioning purposes and they can be used for a preliminary evaluation of the science performance of the instrument. Here we will concentrate on sample spectra covering the whole wavelength region and on the early raster maps acquired in bright lines in the quiet Sun close to disk center. Looking at different quiet Sun features we investigate the thermal structure of the atmosphere and flow structures. For this we apply fits to the spectral profiles and check the performance in terms of Doppler shifts and line widths to retrieve the structure of the network in terms of dynamics. While the amount of data available so far is limited, we will have a first look on how quiet Sun plasma responds to heating events. For this, we will compare spectral lines forming at different temperatures recorded at strictly the same time. Title: Observation of Smallest Ever Detected Brightening Events with the Solar Orbiter EUI HRI-EUV Imager Authors: Parenti, S.; Berghmans, D.; Buchlin, E.; Teriaca, L.; Auchere, F.; Harra, L.; Long, D.; Rochus, P. L.; Schühle, U.; Aznar Cuadrado, R.; Gissot, S.; Kraaikamp, E.; Smith, P.; Stegen, K.; Verbeeck, C. Bibcode: 2020AGUFMSH038..01P Altcode: The Extreme Ultraviolet Imager (EUI) suite on board Solar Orbiter acquired its first images in May 2020. The passband of the 17.4 nm High Resolution Imager (HRI-EUV) is dominated by emission lines of Fe IX and Fe X, that is the 1 million degree solar corona. The solar atmosphere at this temperature is dynamic at all scales, down to the highest spatial resolution available from instruments priori to Solar Orbiter. During the Commissioning phase, HRI-EUV acquired several high temporal resolution (a few seconds) sequences at quiet Sun regions at disk center. The instrument revealed a multitude of brightenings at the smallest-ever detectable spatial scales which, at that time, was about 400 km (two pixels). These events appear to be present everywhere all the time. We present the first results of the analysis of these sequences with the aim of understanding the role of these small scale events in the heating of the solar corona. Title: First Results From SPICE EUV Spectrometer on Solar Orbiter Authors: Fludra, A.; Caldwell, M.; Giunta, A. S.; Grundy, T.; Guest, S.; Sidher, S.; Auchere, F.; Carlsson, M.; Hassler, D.; Peter, H.; Aznar Cuadrado, R.; Buchlin, E.; Caminade, S.; DeForest, C.; Fredvik, T.; Harra, L. K.; Janvier, M.; Kucera, T. A.; Leeks, S.; Mueller, D.; Parenti, S.; Schmutz, W. K.; Schühle, U.; Teriaca, L.; Thompson, W. T.; Tustain, S.; Williams, D.; Young, P. R. Bibcode: 2020AGUFMSH038..02F Altcode: SPICE (Spectral Imaging of Coronal Environment) is one of the remote sensing instruments onboard Solar Orbiter. It is an EUV imaging spectrometer observing the Sun in two wavelength bands: 69.6-79.4 nm and 96.6-105.1 nm. SPICE is capable of recording full spectra in these bands with exposures as short as 1s. SPICE is the only Solar Orbiter instrument that can measure EUV spectra from the disk and low corona of the Sun and record all spectral lines simultaneously. SPICE uses one of three narrow slits, 2"x11', 4''x11', 6''x11', or a wide slit 30''x14'. The primary mirror can be scanned in a direction perpendicular to the slit, allowing raster images of up to 16' in size.

We present an overview of the first SPICE data taken on several days during the instrument commissioning carried out by the RAL Space team between 2020 April 21 and 2020 June 14. We also include results from SPICE observations at the first Solar Orbiter perihelion at 0.52AU, taken between June 16-21st. We give examples of full spectra from the quiet Sun near disk centre and provide a list of key spectral lines emitted in a range of temperatures between 10,000 K and over 1 million K, from neutral hydrogen and ions of carbon, oxygen, nitrogen, neon, sulphur and magnesium. We show examples of first raster images in several strong lines, obtained with different slits and a range of exposure times between 5s and 180s. We describe the temperature coverage and density diagnostics, determination of plasma flows, and discuss possible applications to studies of the elemental abundances in the corona. We also show the first off-limb measurements with SPICE, as obtained when the spacecraft pointed at the limb. Title: The Solar-C (EUVST) mission: the latest status Authors: Shimizu, Toshifumi; Imada, Shinsuke; Kawate, Tomoko; Suematsu, Yoshinori; Hara, Hirohisa; Tsuzuki, Toshihiro; Katsukawa, Yukio; Kubo, Masahito; Ishikawa, Ryoko; Watanabe, Tetsuya; Toriumi, Shin; Ichimoto, Kiyoshi; Nagata, Shin'ichi; Hasegawa, Takahiro; Yokoyama, Takaaki; Watanabe, Kyoko; Tsuno, Katsuhiko; Korendyke, Clarence M.; Warren, Harry; De Pontieu, Bart; Boerner, Paul; Solanki, Sami K.; Teriaca, Luca; Schuehle, Udo; Matthews, Sarah; Long, David; Thomas, William; Hancock, Barry; Reid, Hamish; Fludra, Andrzej; Auchère, Frederic; Andretta, Vincenzo; Naletto, Giampiero; Poletto, Luca; Harra, Louise Bibcode: 2020SPIE11444E..0NS Altcode: Solar-C (EUVST) is the next Japanese solar physics mission to be developed with significant contributions from US and European countries. The mission carries an EUV imaging spectrometer with slit-jaw imaging system called EUVST (EUV High-Throughput Spectroscopic Telescope) as the mission payload, to take a fundamental step towards answering how the plasma universe is created and evolves and how the Sun influences the Earth and other planets in our solar system. In April 2020, ISAS (Institute of Space and Astronautical Science) of JAXA (Japan Aerospace Exploration Agency) has made the final down-selection for this mission as the 4th in the series of competitively chosen M-class mission to be launched with an Epsilon launch vehicle in mid 2020s. NASA (National Aeronautics and Space Administration) has selected this mission concept for Phase A concept study in September 2019 and is in the process leading to final selection. For European countries, the team has (or is in the process of confirming) confirmed endorsement for hardware contributions to the EUVST from the national agencies. A recent update to the mission instrumentation is to add a UV spectral irradiance monitor capability for EUVST calibration and scientific purpose. This presentation provides the latest status of the mission with an overall description of the mission concept emphasizing on key roles of the mission in heliophysics research from mid 2020s. Title: Current Status of the Solar-C_EUVST Mission Authors: Imada, S.; Shimizu, T.; Kawate, T.; Toriumi, S.; Katsukawa, Y.; Kubo, M.; Hara, H.; Suematsu, Y.; Ichimoto, K.; Watanabe, T.; Watanabe, K.; Yokoyama, T.; Warren, H.; Long, D.; Harra, L. K.; Teriaca, L. Bibcode: 2020AGUFMSH056..05I Altcode: Solar-C_EUVST (EUV High-Throughput Spectroscopic Telescope) is designed to comprehensively understand the energy and mass transfer from the solar surface to the solar corona and interplanetary space, and to investigate the elementary processes that take place universally in cosmic plasmas. As a fundamental step towards answering how the plasma universe is created and evolves, and how the Sun influences the Earth and other planets in our solar system, the proposed mission is designed to comprehensively understand how mass and energy are transferred throughout the solar atmosphere. Understanding the solar atmosphere, which connects to the heliosphere via radiation, the solar wind and coronal mass ejections, and energetic particles is pivotal for establishing the conditions for life and habitability in the solar system.

The two primary science objectives for Solar-C_EUVST are : I) Understand how fundamental processes lead to the formation of the solar atmosphere and the solar wind, II) Understand how the solar atmosphere becomes unstable, releasing the energy that drives solar flares and eruptions. Solar-C_EUVST will, A) seamlessly observe all the temperature regimes of the solar atmosphere from the chromosphere to the corona at the same time, B) resolve elemental structures of the solar atmosphere with high spatial resolution and cadence to track their evolution, and C) obtain spectroscopic information on the dynamics of elementary processes taking place in the solar atmosphere.

In this talk, we will first discuss the science target of the Solar-C_EUVST, and then discuss the current status of the Solar-C_EUVST mission. Title: Calibrating optical distortions in the Solar Orbiter SPICE spectrograph Authors: Thompson, W. T.; Schühle, U.; Young, P. R.; Auchere, F.; Carlsson, M.; Fludra, A.; Hassler, D.; Peter, H.; Aznar Cuadrado, R.; Buchlin, E.; Caldwell, M.; DeForest, C.; Fredvik, T.; Harra, L. K.; Janvier, M.; Kucera, T. A.; Giunta, A. S.; Grundy, T.; Müller, D.; Parenti, S.; Caminade, S.; Schmutz, W. K.; Teriaca, L.; Williams, D.; Sidher, S. Bibcode: 2020AGUFMSH0360029T Altcode: The Spectral Imaging of the Coronal Environment (SPICE) instrument on Solar Orbiter is a high-resolution imaging spectrometer operating at extreme ultraviolet (EUV) wavelengths from 70.4-79.0 nm and 97.3-104.9 nm. A single-mirror off-axis paraboloid focuses the solar image onto the entrance slit of the spectrometer section. A Toroidal Variable Line Space (TVLS) grating images the entrance slit onto a pair of MCP-intensified APS detectors. Ray-tracing analysis prior to launch showed that the instrument was subject to a number of small image distortions which need to be corrected in the final data product. We compare the ray tracing results with measurements made in flight. Co-alignment with other telescopes on Solar Orbiter will also be examined. Title: First results from the EUI and SPICE observations of Alpha Leo near Solar Orbiter first perihelion Authors: Buchlin, E.; Teriaca, L.; Giunta, A. S.; Grundy, T.; Andretta, V.; Auchere, F.; Peter, H.; Berghmans, D.; Carlsson, M.; Fludra, A.; Harra, L.; Hassler, D.; Long, D.; Rochus, P. L.; Schühle, U.; Aznar Cuadrado, R.; Caldwell, M.; Caminade, S.; DeForest, C.; Fredvik, T.; Gissot, S.; Heerlein, K.; Janvier, M.; Kraaikamp, E.; Kucera, T. A.; Müller, D.; Parenti, S.; Schmutz, W. K.; Sidher, S.; Smith, P.; Stegen, K.; Thompson, W. T.; Verbeeck, C.; Williams, D.; Young, P. R. Bibcode: 2020AGUFMSH0360024B Altcode: On June 16th 2020 Solar Orbiter made a dedicated observing campaign where the spacecraft pointed to the solar limb to allow some of the high resolution instruments to observe the ingress (at the east limb) and later the egress (west limb) of the occultation of the star Alpha Leonis by the solar disk. The star was chosen because its luminosity and early spectral type ensure high and stable flux at wavelengths between 100 and 122 nanometers, a range observed by the High Resolution EUI Lyman alpha telescope (HRI-LYA) and by the long wavelength channel of the SPICE spectrograph. Star observations, when feasible, allow to gather a great deal of information on the instrument performances, such as the radiometric performance and the instrument optical point spread function (PSF).

We report here the first results from the above campaign for the two instruments. Title: Solar Orbiter: connecting remote sensing and in situ measurements Authors: Horbury, T. S.; Auchere, F.; Antonucci, E.; Berghmans, D.; Bruno, R.; Carlsson, M.; del Toro Iniesta, J. C.; Fludra, A.; Harra, L.; Hassler, D.; Heinzel, P.; Howard, R. A.; Krucker, S.; Livi, S. A.; Long, D.; Louarn, P.; Maksimovic, M.; Mueller, D.; Owen, C. J.; Peter, H.; Rochus, P. L.; Rodriguez-Pacheco, J.; Romoli, M.; Schühle, U.; Solanki, S. K.; Teriaca, L.; Wimmer-Schweingruber, R. F.; Zouganelis, Y.; Laker, R. Bibcode: 2020AGUFMSH038..10H Altcode: A key science goal of the Solar Orbiter mission is to make connections between phenomena on the Sun and their manifestations in interplanetary space. To that end, the spacecraft carries a carefully tailored payload of six remote sensing instruments and four making in situ measurements. During June 2020, while the spacecraft was around 0.5 AU from the Sun, the remote sensing instruments operated for several days. While this was primarily an engineering activity, the resulting observations provided outstanding measurements and represent the ideal first opportunity to investigate the potential for making connections between the remote sensing and in situ payloads on Solar Orbiter.

We present a preliminary analysis of the available remote sensing and in situ observations, showing how connections can be made, and discuss the potential for further, more precise mapping to be performed as the mission progresses. Title: First Images and Initial In-Flight Performance of the Extreme Ultraviolet Imager On-Board Solar Orbiter. Authors: Auchere, F.; Gissot, S.; Teriaca, L.; Berghmans, D.; Harra, L.; Long, D.; Rochus, P. L.; Smith, P.; Schühle, U.; Stegen, K.; Aznar Cuadrado, R.; Heerlein, K.; Kraaikamp, E.; Verbeeck, C. Bibcode: 2020AGUFMSH0360025A Altcode: The Extreme Ultraviolet Imager (EUI) on board Solar Orbiter is composed of two High Resolution Imagers working at 121.6 (HRI-LYA, H I, chromosphere) and 17.4 nm (HRI-EUV, Fe IX/X, corona) and one dual-band Full Sun Imager (FSI) working at 30.4 nm (He II, transition region) and 17.4 nm (Fe IX/X, corona). During the commissioning period following the launch of Solar Orbiter and two and a half months of outgassing, EUI acquired its first solar images on May 12th, 2020 at about 0.67 AU. Most of the capabilities of the instrument have been tested during the following weeks, which revealed excellent overall performance. HRI-EUV already provided images with an angular resolution equivalent to ~0.6" (2 pixels) at 1 A.U. HRI-LYA will routinely provide images of the Sun at Lyman alpha, which have been otherwise relatively rare, with sub-second cadence capability. FSI will provide context for connection science but it will also explore regions of the corona never imaged before at EUV wavelengths, owing to its 3.8° field of view. EUI uses a complex on-board image processing system including advanced image compression and event detection algorithms. In particular, commissioning tests confirm the good performance of the compression, which is critical given the limited total telemetry volume imposed by the mission profile. In this paper, we present the main characteristics of the first images taken in each channel and we provide an initial assessment of the in-flight performance. Title: First results from combined EUI and SPICE observations of Lyman lines of Hydrogen and He II Authors: Teriaca, L.; Aznar Cuadrado, R.; Giunta, A. S.; Grundy, T.; Parenti, S.; Auchere, F.; Vial, J. C.; Fludra, A.; Berghmans, D.; Carlsson, M.; Harra, L.; Hassler, D.; Long, D.; Peter, H.; Rochus, P. L.; Schühle, U.; Buchlin, E.; Caldwell, M.; Caminade, S.; DeForest, C.; Fredvik, T.; Gissot, S.; Heerlein, K.; Janvier, M.; Kraaikamp, E.; Kucera, T. A.; Mueller, D.; Schmutz, W. K.; Sidher, S.; Smith, P.; Stegen, K.; Thompson, W. T.; Verbeeck, C.; Williams, D.; Young, P. R. Bibcode: 2020AGUFMSH0360003T Altcode: The Solar Orbiter spacecraft carries a powerful set of remote sensing instruments that allow studying the solar atmosphere with unprecedented diagnostic capabilities. Many such diagnostics require the simultaneous usage of more than one instrument. One example of that is the capability, for the first time, to obtain (near) simultaneous spatially resolved observations of the emission from the first three lines of the Lyman series of hydrogen and of He II Lyman alpha. In fact, the SPectral Imaging of the Coronal Environment (SPICE) spectrometer can observe the Lyman beta and gamma lines in its long wavelength (SPICE-LW) channel, the High Resolution Lyman Alpha (HRI-LYA) telescope of the Extreme Ultraviolet Imager (EUI) acquires narrow band images in the Lyman alpha line while the Full Disk Imager (FSI) of EUI can take images dominated by the Lyman alpha line of ionized Helium at 30.4 nm (FSI-304). Being hydrogen and helium the main components of our star, these very bright transitions play an important role in the energy budget of the outer atmosphere via radiative losses and the measurement of their profiles and radiance ratios is a fundamental constraint to any comprehensive modelization effort of the upper solar chromosphere and transition region. Additionally, monitoring their average ratios can serve as a check out for the relative radiometric performance of the two instruments throughout the mission. Although the engineering data acquired so far are far from ideal in terms of time simultaneity (often only within about 1 h) and line coverage (often only Lyman beta was acquired by SPICE and not always near simultaneous images from all three telescopes are available) the analysis we present here still offers a great opportunity to have a first look at the potential of this diagnostic from the two instruments. In fact, we have identified a series of datasets obtained at disk center and at various positions at the solar limb that allow studying the Lyman alpha to beta radiance ratio and their relation to He II 30.4 as a function of the position on the Sun (disk center versus limb and quiet Sun versus coronal holes). Title: Very high-resolution observations of the solar atmosphere in H I Lyman alpha and Fe IX-X at 17.4 nm as seen by EUI aboard Solar Orbiter Authors: Aznar Cuadrado, R.; Berghmans, D.; Teriaca, L.; Gissot, S.; Schühle, U.; Auchere, F.; Harra, L.; Long, D.; Rochus, P. L.; Heerlein, K.; Kraaikamp, E.; Smith, P.; Stegen, K.; Verbeeck, C. Bibcode: 2020AGUFMSH0360026A Altcode: The Extreme Ultraviolet Imager (EUI) aboard Solar Orbiter consists of three telescopes, the Full Sun Imager (FSI) and two High Resolution Imagers (HRIs). The two HRI telescopes provide images of the base of the corona, near to the chromosphere, and of the 1 million K corona. In fact, the HRI-EUV telescope operates around 17.4 nm to obtain images dominated by emission from lines generated from Fe-IX and X ions, formed at about 1 MK, while the HRI-LYA telescope provides narrow band images dominated by the H I Lyman alpha line at 121.6 nm, formed in the upper chromosphere/lower transition region of the solar atmosphere around 20,000 K. Thus, the two imagers provide a powerful diagnostics of the solar structural organization, in terms of loop hierarchies and connectivity. Here we present an analysis of the first two near-simultaneous (within 15s) high-resolution images of the solar quiet atmosphere obtained near disk center by the two high-resolution telescopes on May 30th 2020, during the commissioning phase of the mission , when Solar Orbiter was at about 0.56 AU from the Sun. Title: A sensitivity analysis of the updated optical design for EUVST on the Solar-C mission Authors: Kawate, Tomoko; Tsuzuki, Toshihiro; Shimizu, Toshifumi; Imada, Shinsuke; Katsukawa, Yukio; Hara, Hirohisa; Suematsu, Yoshinori; Ichimoto, Kiyoshi; Hattori, Tomoya; Narasaki, Shota; Warren, Harry P.; Teriaca, Luca; Korendyke, Clarence M.; Brown, Charles M.; Auchere, Frederic Bibcode: 2020SPIE11444E..3JK Altcode: The EUV high-throughput spectroscopic telescope (EUVST) onboard the Solar-C mission has the high spatial (0.4'') resolution over a wide wavelength range in the vacuum ultraviolet. To achieve high spatial resolution under a design constraint given by the JAXA Epsilon launch vehicle, we further update the optical design to secure margins needed to realize 0.4'' spatial resolution over a field of view of 100''×100''. To estimate the error budgets of spatial and spectral resolutions due to installation and fabrication errors, we perform a sensitivity analysis for the position and orientation of each optical element and for the grating parameters by ray tracing with the Zemax software. We obtain point spread functions (PSF) for rays from 9 fields and at 9 wavelengths on each detector by changing each parameter slightly. A full width at half maximum (FWHM) of the PSF is derived at each field and wavelength position as a function of the perturbation of each optical parameter. Assuming a mount system of each optical element and an error of each optical parameter, we estimate spatial and spectral resolutions by taking installation and fabrication errors into account. The results of the sensitivity analysis suggest that budgets of the total of optical design and the assembly errors account for 15% and 5.8% of our budgets of the spatial resolution in the long wavelength and short wavelength bands, respectively. On the other hand, the grating fabrication errors give a large degradation of spatial and spectral resolutions, and investigations of compensators are needed to relax the fabrication tolerance of the grating surface parameters. Title: Coordination within the remote sensing payload on the Solar Orbiter mission Authors: Auchère, F.; Andretta, V.; Antonucci, E.; Bach, N.; Battaglia, M.; Bemporad, A.; Berghmans, D.; Buchlin, E.; Caminade, S.; Carlsson, M.; Carlyle, J.; Cerullo, J. J.; Chamberlin, P. C.; Colaninno, R. C.; Davila, J. M.; De Groof, A.; Etesi, L.; Fahmy, S.; Fineschi, S.; Fludra, A.; Gilbert, H. R.; Giunta, A.; Grundy, T.; Haberreiter, M.; Harra, L. K.; Hassler, D. M.; Hirzberger, J.; Howard, R. A.; Hurford, G.; Kleint, L.; Kolleck, M.; Krucker, S.; Lagg, A.; Landini, F.; Long, D. M.; Lefort, J.; Lodiot, S.; Mampaey, B.; Maloney, S.; Marliani, F.; Martinez-Pillet, V.; McMullin, D. R.; Müller, D.; Nicolini, G.; Orozco Suarez, D.; Pacros, A.; Pancrazzi, M.; Parenti, S.; Peter, H.; Philippon, A.; Plunkett, S.; Rich, N.; Rochus, P.; Rouillard, A.; Romoli, M.; Sanchez, L.; Schühle, U.; Sidher, S.; Solanki, S. K.; Spadaro, D.; St Cyr, O. C.; Straus, T.; Tanco, I.; Teriaca, L.; Thompson, W. T.; del Toro Iniesta, J. C.; Verbeeck, C.; Vourlidas, A.; Watson, C.; Wiegelmann, T.; Williams, D.; Woch, J.; Zhukov, A. N.; Zouganelis, I. Bibcode: 2020A&A...642A...6A Altcode: Context. To meet the scientific objectives of the mission, the Solar Orbiter spacecraft carries a suite of in-situ (IS) and remote sensing (RS) instruments designed for joint operations with inter-instrument communication capabilities. Indeed, previous missions have shown that the Sun (imaged by the RS instruments) and the heliosphere (mainly sampled by the IS instruments) should be considered as an integrated system rather than separate entities. Many of the advances expected from Solar Orbiter rely on this synergistic approach between IS and RS measurements.
Aims: Many aspects of hardware development, integration, testing, and operations are common to two or more RS instruments. In this paper, we describe the coordination effort initiated from the early mission phases by the Remote Sensing Working Group. We review the scientific goals and challenges, and give an overview of the technical solutions devised to successfully operate these instruments together.
Methods: A major constraint for the RS instruments is the limited telemetry (TM) bandwidth of the Solar Orbiter deep-space mission compared to missions in Earth orbit. Hence, many of the strategies developed to maximise the scientific return from these instruments revolve around the optimisation of TM usage, relying for example on onboard autonomy for data processing, compression, and selection for downlink. The planning process itself has been optimised to alleviate the dynamic nature of the targets, and an inter-instrument communication scheme has been implemented which can be used to autonomously alter the observing modes. We also outline the plans for in-flight cross-calibration, which will be essential to the joint data reduction and analysis.
Results: The RS instrument package on Solar Orbiter will carry out comprehensive measurements from the solar interior to the inner heliosphere. Thanks to the close coordination between the instrument teams and the European Space Agency, several challenges specific to the RS suite were identified and addressed in a timely manner. Title: Models and data analysis tools for the Solar Orbiter mission Authors: Rouillard, A. P.; Pinto, R. F.; Vourlidas, A.; De Groof, A.; Thompson, W. T.; Bemporad, A.; Dolei, S.; Indurain, M.; Buchlin, E.; Sasso, C.; Spadaro, D.; Dalmasse, K.; Hirzberger, J.; Zouganelis, I.; Strugarek, A.; Brun, A. S.; Alexandre, M.; Berghmans, D.; Raouafi, N. E.; Wiegelmann, T.; Pagano, P.; Arge, C. N.; Nieves-Chinchilla, T.; Lavarra, M.; Poirier, N.; Amari, T.; Aran, A.; Andretta, V.; Antonucci, E.; Anastasiadis, A.; Auchère, F.; Bellot Rubio, L.; Nicula, B.; Bonnin, X.; Bouchemit, M.; Budnik, E.; Caminade, S.; Cecconi, B.; Carlyle, J.; Cernuda, I.; Davila, J. M.; Etesi, L.; Espinosa Lara, F.; Fedorov, A.; Fineschi, S.; Fludra, A.; Génot, V.; Georgoulis, M. K.; Gilbert, H. R.; Giunta, A.; Gomez-Herrero, R.; Guest, S.; Haberreiter, M.; Hassler, D.; Henney, C. J.; Howard, R. A.; Horbury, T. S.; Janvier, M.; Jones, S. I.; Kozarev, K.; Kraaikamp, E.; Kouloumvakos, A.; Krucker, S.; Lagg, A.; Linker, J.; Lavraud, B.; Louarn, P.; Maksimovic, M.; Maloney, S.; Mann, G.; Masson, A.; Müller, D.; Önel, H.; Osuna, P.; Orozco Suarez, D.; Owen, C. J.; Papaioannou, A.; Pérez-Suárez, D.; Rodriguez-Pacheco, J.; Parenti, S.; Pariat, E.; Peter, H.; Plunkett, S.; Pomoell, J.; Raines, J. M.; Riethmüller, T. L.; Rich, N.; Rodriguez, L.; Romoli, M.; Sanchez, L.; Solanki, S. K.; St Cyr, O. C.; Straus, T.; Susino, R.; Teriaca, L.; del Toro Iniesta, J. C.; Ventura, R.; Verbeeck, C.; Vilmer, N.; Warmuth, A.; Walsh, A. P.; Watson, C.; Williams, D.; Wu, Y.; Zhukov, A. N. Bibcode: 2020A&A...642A...2R Altcode: Context. The Solar Orbiter spacecraft will be equipped with a wide range of remote-sensing (RS) and in situ (IS) instruments to record novel and unprecedented measurements of the solar atmosphere and the inner heliosphere. To take full advantage of these new datasets, tools and techniques must be developed to ease multi-instrument and multi-spacecraft studies. In particular the currently inaccessible low solar corona below two solar radii can only be observed remotely. Furthermore techniques must be used to retrieve coronal plasma properties in time and in three dimensional (3D) space. Solar Orbiter will run complex observation campaigns that provide interesting opportunities to maximise the likelihood of linking IS data to their source region near the Sun. Several RS instruments can be directed to specific targets situated on the solar disk just days before data acquisition. To compare IS and RS, data we must improve our understanding of how heliospheric probes magnetically connect to the solar disk.
Aims: The aim of the present paper is to briefly review how the current modelling of the Sun and its atmosphere can support Solar Orbiter science. We describe the results of a community-led effort by European Space Agency's Modelling and Data Analysis Working Group (MADAWG) to develop different models, tools, and techniques deemed necessary to test different theories for the physical processes that may occur in the solar plasma. The focus here is on the large scales and little is described with regards to kinetic processes. To exploit future IS and RS data fully, many techniques have been adapted to model the evolving 3D solar magneto-plasma from the solar interior to the solar wind. A particular focus in the paper is placed on techniques that can estimate how Solar Orbiter will connect magnetically through the complex coronal magnetic fields to various photospheric and coronal features in support of spacecraft operations and future scientific studies.
Methods: Recent missions such as STEREO, provided great opportunities for RS, IS, and multi-spacecraft studies. We summarise the achievements and highlight the challenges faced during these investigations, many of which motivated the Solar Orbiter mission. We present the new tools and techniques developed by the MADAWG to support the science operations and the analysis of the data from the many instruments on Solar Orbiter.
Results: This article reviews current modelling and tool developments that ease the comparison of model results with RS and IS data made available by current and upcoming missions. It also describes the modelling strategy to support the science operations and subsequent exploitation of Solar Orbiter data in order to maximise the scientific output of the mission.
Conclusions: The on-going community effort presented in this paper has provided new models and tools necessary to support mission operations as well as the science exploitation of the Solar Orbiter data. The tools and techniques will no doubt evolve significantly as we refine our procedure and methodology during the first year of operations of this highly promising mission. Title: The Solar Orbiter Science Activity Plan. Translating solar and heliospheric physics questions into action Authors: Zouganelis, I.; De Groof, A.; Walsh, A. P.; Williams, D. R.; Müller, D.; St Cyr, O. C.; Auchère, F.; Berghmans, D.; Fludra, A.; Horbury, T. S.; Howard, R. A.; Krucker, S.; Maksimovic, M.; Owen, C. J.; Rodríguez-Pacheco, J.; Romoli, M.; Solanki, S. K.; Watson, C.; Sanchez, L.; Lefort, J.; Osuna, P.; Gilbert, H. R.; Nieves-Chinchilla, T.; Abbo, L.; Alexandrova, O.; Anastasiadis, A.; Andretta, V.; Antonucci, E.; Appourchaux, T.; Aran, A.; Arge, C. N.; Aulanier, G.; Baker, D.; Bale, S. D.; Battaglia, M.; Bellot Rubio, L.; Bemporad, A.; Berthomier, M.; Bocchialini, K.; Bonnin, X.; Brun, A. S.; Bruno, R.; Buchlin, E.; Büchner, J.; Bucik, R.; Carcaboso, F.; Carr, R.; Carrasco-Blázquez, I.; Cecconi, B.; Cernuda Cangas, I.; Chen, C. H. K.; Chitta, L. P.; Chust, T.; Dalmasse, K.; D'Amicis, R.; Da Deppo, V.; De Marco, R.; Dolei, S.; Dolla, L.; Dudok de Wit, T.; van Driel-Gesztelyi, L.; Eastwood, J. P.; Espinosa Lara, F.; Etesi, L.; Fedorov, A.; Félix-Redondo, F.; Fineschi, S.; Fleck, B.; Fontaine, D.; Fox, N. J.; Gandorfer, A.; Génot, V.; Georgoulis, M. K.; Gissot, S.; Giunta, A.; Gizon, L.; Gómez-Herrero, R.; Gontikakis, C.; Graham, G.; Green, L.; Grundy, T.; Haberreiter, M.; Harra, L. K.; Hassler, D. M.; Hirzberger, J.; Ho, G. C.; Hurford, G.; Innes, D.; Issautier, K.; James, A. W.; Janitzek, N.; Janvier, M.; Jeffrey, N.; Jenkins, J.; Khotyaintsev, Y.; Klein, K. -L.; Kontar, E. P.; Kontogiannis, I.; Krafft, C.; Krasnoselskikh, V.; Kretzschmar, M.; Labrosse, N.; Lagg, A.; Landini, F.; Lavraud, B.; Leon, I.; Lepri, S. T.; Lewis, G. R.; Liewer, P.; Linker, J.; Livi, S.; Long, D. M.; Louarn, P.; Malandraki, O.; Maloney, S.; Martinez-Pillet, V.; Martinovic, M.; Masson, A.; Matthews, S.; Matteini, L.; Meyer-Vernet, N.; Moraitis, K.; Morton, R. J.; Musset, S.; Nicolaou, G.; Nindos, A.; O'Brien, H.; Orozco Suarez, D.; Owens, M.; Pancrazzi, M.; Papaioannou, A.; Parenti, S.; Pariat, E.; Patsourakos, S.; Perrone, D.; Peter, H.; Pinto, R. F.; Plainaki, C.; Plettemeier, D.; Plunkett, S. P.; Raines, J. M.; Raouafi, N.; Reid, H.; Retino, A.; Rezeau, L.; Rochus, P.; Rodriguez, L.; Rodriguez-Garcia, L.; Roth, M.; Rouillard, A. P.; Sahraoui, F.; Sasso, C.; Schou, J.; Schühle, U.; Sorriso-Valvo, L.; Soucek, J.; Spadaro, D.; Stangalini, M.; Stansby, D.; Steller, M.; Strugarek, A.; Štverák, Š.; Susino, R.; Telloni, D.; Terasa, C.; Teriaca, L.; Toledo-Redondo, S.; del Toro Iniesta, J. C.; Tsiropoula, G.; Tsounis, A.; Tziotziou, K.; Valentini, F.; Vaivads, A.; Vecchio, A.; Velli, M.; Verbeeck, C.; Verdini, A.; Verscharen, D.; Vilmer, N.; Vourlidas, A.; Wicks, R.; Wimmer-Schweingruber, R. F.; Wiegelmann, T.; Young, P. R.; Zhukov, A. N. Bibcode: 2020A&A...642A...3Z Altcode: 2020arXiv200910772Z Solar Orbiter is the first space mission observing the solar plasma both in situ and remotely, from a close distance, in and out of the ecliptic. The ultimate goal is to understand how the Sun produces and controls the heliosphere, filling the Solar System and driving the planetary environments. With six remote-sensing and four in-situ instrument suites, the coordination and planning of the operations are essential to address the following four top-level science questions: (1) What drives the solar wind and where does the coronal magnetic field originate?; (2) How do solar transients drive heliospheric variability?; (3) How do solar eruptions produce energetic particle radiation that fills the heliosphere?; (4) How does the solar dynamo work and drive connections between the Sun and the heliosphere? Maximising the mission's science return requires considering the characteristics of each orbit, including the relative position of the spacecraft to Earth (affecting downlink rates), trajectory events (such as gravitational assist manoeuvres), and the phase of the solar activity cycle. Furthermore, since each orbit's science telemetry will be downloaded over the course of the following orbit, science operations must be planned at mission level, rather than at the level of individual orbits. It is important to explore the way in which those science questions are translated into an actual plan of observations that fits into the mission, thus ensuring that no opportunities are missed. First, the overarching goals are broken down into specific, answerable questions along with the required observations and the so-called Science Activity Plan (SAP) is developed to achieve this. The SAP groups objectives that require similar observations into Solar Orbiter Observing Plans, resulting in a strategic, top-level view of the optimal opportunities for science observations during the mission lifetime. This allows for all four mission goals to be addressed. In this paper, we introduce Solar Orbiter's SAP through a series of examples and the strategy being followed. Title: The Solar Orbiter SPICE instrument. An extreme UV imaging spectrometer Authors: SPICE Consortium; Anderson, M.; Appourchaux, T.; Auchère, F.; Aznar Cuadrado, R.; Barbay, J.; Baudin, F.; Beardsley, S.; Bocchialini, K.; Borgo, B.; Bruzzi, D.; Buchlin, E.; Burton, G.; Büchel, V.; Caldwell, M.; Caminade, S.; Carlsson, M.; Curdt, W.; Davenne, J.; Davila, J.; Deforest, C. E.; Del Zanna, G.; Drummond, D.; Dubau, J.; Dumesnil, C.; Dunn, G.; Eccleston, P.; Fludra, A.; Fredvik, T.; Gabriel, A.; Giunta, A.; Gottwald, A.; Griffin, D.; Grundy, T.; Guest, S.; Gyo, M.; Haberreiter, M.; Hansteen, V.; Harrison, R.; Hassler, D. M.; Haugan, S. V. H.; Howe, C.; Janvier, M.; Klein, R.; Koller, S.; Kucera, T. A.; Kouliche, D.; Marsch, E.; Marshall, A.; Marshall, G.; Matthews, S. A.; McQuirk, C.; Meining, S.; Mercier, C.; Morris, N.; Morse, T.; Munro, G.; Parenti, S.; Pastor-Santos, C.; Peter, H.; Pfiffner, D.; Phelan, P.; Philippon, A.; Richards, A.; Rogers, K.; Sawyer, C.; Schlatter, P.; Schmutz, W.; Schühle, U.; Shaughnessy, B.; Sidher, S.; Solanki, S. K.; Speight, R.; Spescha, M.; Szwec, N.; Tamiatto, C.; Teriaca, L.; Thompson, W.; Tosh, I.; Tustain, S.; Vial, J. -C.; Walls, B.; Waltham, N.; Wimmer-Schweingruber, R.; Woodward, S.; Young, P.; de Groof, A.; Pacros, A.; Williams, D.; Müller, D. Bibcode: 2020A&A...642A..14S Altcode: 2019arXiv190901183A; 2019arXiv190901183S
Aims: The Spectral Imaging of the Coronal Environment (SPICE) instrument is a high-resolution imaging spectrometer operating at extreme ultraviolet wavelengths. In this paper, we present the concept, design, and pre-launch performance of this facility instrument on the ESA/NASA Solar Orbiter mission.
Methods: The goal of this paper is to give prospective users a better understanding of the possible types of observations, the data acquisition, and the sources that contribute to the instrument's signal.
Results: The paper discusses the science objectives, with a focus on the SPICE-specific aspects, before presenting the instrument's design, including optical, mechanical, thermal, and electronics aspects. This is followed by a characterisation and calibration of the instrument's performance. The paper concludes with descriptions of the operations concept and data processing.
Conclusions: The performance measurements of the various instrument parameters meet the requirements derived from the mission's science objectives. The SPICE instrument is ready to perform measurements that will provide vital contributions to the scientific success of the Solar Orbiter mission. Title: The Solar Orbiter mission. Science overview Authors: Müller, D.; St. Cyr, O. C.; Zouganelis, I.; Gilbert, H. R.; Marsden, R.; Nieves-Chinchilla, T.; Antonucci, E.; Auchère, F.; Berghmans, D.; Horbury, T. S.; Howard, R. A.; Krucker, S.; Maksimovic, M.; Owen, C. J.; Rochus, P.; Rodriguez-Pacheco, J.; Romoli, M.; Solanki, S. K.; Bruno, R.; Carlsson, M.; Fludra, A.; Harra, L.; Hassler, D. M.; Livi, S.; Louarn, P.; Peter, H.; Schühle, U.; Teriaca, L.; del Toro Iniesta, J. C.; Wimmer-Schweingruber, R. F.; Marsch, E.; Velli, M.; De Groof, A.; Walsh, A.; Williams, D. Bibcode: 2020A&A...642A...1M Altcode: 2020arXiv200900861M
Aims: Solar Orbiter, the first mission of ESA's Cosmic Vision 2015-2025 programme and a mission of international collaboration between ESA and NASA, will explore the Sun and heliosphere from close up and out of the ecliptic plane. It was launched on 10 February 2020 04:03 UTC from Cape Canaveral and aims to address key questions of solar and heliospheric physics pertaining to how the Sun creates and controls the Heliosphere, and why solar activity changes with time. To answer these, the mission carries six remote-sensing instruments to observe the Sun and the solar corona, and four in-situ instruments to measure the solar wind, energetic particles, and electromagnetic fields. In this paper, we describe the science objectives of the mission, and how these will be addressed by the joint observations of the instruments onboard.
Methods: The paper first summarises the mission-level science objectives, followed by an overview of the spacecraft and payload. We report the observables and performance figures of each instrument, as well as the trajectory design. This is followed by a summary of the science operations concept. The paper concludes with a more detailed description of the science objectives.
Results: Solar Orbiter will combine in-situ measurements in the heliosphere with high-resolution remote-sensing observations of the Sun to address fundamental questions of solar and heliospheric physics. The performance of the Solar Orbiter payload meets the requirements derived from the mission's science objectives. Its science return will be augmented further by coordinated observations with other space missions and ground-based observatories.

ARRAY(0x207ce98) Title: The Solar Orbiter EUI instrument: The Extreme Ultraviolet Imager Authors: Rochus, P.; Auchère, F.; Berghmans, D.; Harra, L.; Schmutz, W.; Schühle, U.; Addison, P.; Appourchaux, T.; Aznar Cuadrado, R.; Baker, D.; Barbay, J.; Bates, D.; BenMoussa, A.; Bergmann, M.; Beurthe, C.; Borgo, B.; Bonte, K.; Bouzit, M.; Bradley, L.; Büchel, V.; Buchlin, E.; Büchner, J.; Cabé, F.; Cadiergues, L.; Chaigneau, M.; Chares, B.; Choque Cortez, C.; Coker, P.; Condamin, M.; Coumar, S.; Curdt, W.; Cutler, J.; Davies, D.; Davison, G.; Defise, J. -M.; Del Zanna, G.; Delmotte, F.; Delouille, V.; Dolla, L.; Dumesnil, C.; Dürig, F.; Enge, R.; François, S.; Fourmond, J. -J.; Gillis, J. -M.; Giordanengo, B.; Gissot, S.; Green, L. M.; Guerreiro, N.; Guilbaud, A.; Gyo, M.; Haberreiter, M.; Hafiz, A.; Hailey, M.; Halain, J. -P.; Hansotte, J.; Hecquet, C.; Heerlein, K.; Hellin, M. -L.; Hemsley, S.; Hermans, A.; Hervier, V.; Hochedez, J. -F.; Houbrechts, Y.; Ihsan, K.; Jacques, L.; Jérôme, A.; Jones, J.; Kahle, M.; Kennedy, T.; Klaproth, M.; Kolleck, M.; Koller, S.; Kotsialos, E.; Kraaikamp, E.; Langer, P.; Lawrenson, A.; Le Clech', J. -C.; Lenaerts, C.; Liebecq, S.; Linder, D.; Long, D. M.; Mampaey, B.; Markiewicz-Innes, D.; Marquet, B.; Marsch, E.; Matthews, S.; Mazy, E.; Mazzoli, A.; Meining, S.; Meltchakov, E.; Mercier, R.; Meyer, S.; Monecke, M.; Monfort, F.; Morinaud, G.; Moron, F.; Mountney, L.; Müller, R.; Nicula, B.; Parenti, S.; Peter, H.; Pfiffner, D.; Philippon, A.; Phillips, I.; Plesseria, J. -Y.; Pylyser, E.; Rabecki, F.; Ravet-Krill, M. -F.; Rebellato, J.; Renotte, E.; Rodriguez, L.; Roose, S.; Rosin, J.; Rossi, L.; Roth, P.; Rouesnel, F.; Roulliay, M.; Rousseau, A.; Ruane, K.; Scanlan, J.; Schlatter, P.; Seaton, D. B.; Silliman, K.; Smit, S.; Smith, P. J.; Solanki, S. K.; Spescha, M.; Spencer, A.; Stegen, K.; Stockman, Y.; Szwec, N.; Tamiatto, C.; Tandy, J.; Teriaca, L.; Theobald, C.; Tychon, I.; van Driel-Gesztelyi, L.; Verbeeck, C.; Vial, J. -C.; Werner, S.; West, M. J.; Westwood, D.; Wiegelmann, T.; Willis, G.; Winter, B.; Zerr, A.; Zhang, X.; Zhukov, A. N. Bibcode: 2020A&A...642A...8R Altcode: Context. The Extreme Ultraviolet Imager (EUI) is part of the remote sensing instrument package of the ESA/NASA Solar Orbiter mission that will explore the inner heliosphere and observe the Sun from vantage points close to the Sun and out of the ecliptic. Solar Orbiter will advance the "connection science" between solar activity and the heliosphere.
Aims: With EUI we aim to improve our understanding of the structure and dynamics of the solar atmosphere, globally as well as at high resolution, and from high solar latitude perspectives.
Methods: The EUI consists of three telescopes, the Full Sun Imager and two High Resolution Imagers, which are optimised to image in Lyman-α and EUV (17.4 nm, 30.4 nm) to provide a coverage from chromosphere up to corona. The EUI is designed to cope with the strong constraints imposed by the Solar Orbiter mission characteristics. Limited telemetry availability is compensated by state-of-the-art image compression, onboard image processing, and event selection. The imposed power limitations and potentially harsh radiation environment necessitate the use of novel CMOS sensors. As the unobstructed field of view of the telescopes needs to protrude through the spacecraft's heat shield, the apertures have been kept as small as possible, without compromising optical performance. This led to a systematic effort to optimise the throughput of every optical element and the reduction of noise levels in the sensor.
Results: In this paper we review the design of the two elements of the EUI instrument: the Optical Bench System and the Common Electronic Box. Particular attention is also given to the onboard software, the intended operations, the ground software, and the foreseen data products.
Conclusions: The EUI will bring unique science opportunities thanks to its specific design, its viewpoint, and to the planned synergies with the other Solar Orbiter instruments. In particular, we highlight science opportunities brought by the out-of-ecliptic vantage point of the solar poles, the high-resolution imaging of the high chromosphere and corona, and the connection to the outer corona as observed by coronagraphs. Title: Metis: the Solar Orbiter visible light and ultraviolet coronal imager Authors: Antonucci, Ester; Romoli, Marco; Andretta, Vincenzo; Fineschi, Silvano; Heinzel, Petr; Moses, J. Daniel; Naletto, Giampiero; Nicolini, Gianalfredo; Spadaro, Daniele; Teriaca, Luca; Berlicki, Arkadiusz; Capobianco, Gerardo; Crescenzio, Giuseppe; Da Deppo, Vania; Focardi, Mauro; Frassetto, Fabio; Heerlein, Klaus; Landini, Federico; Magli, Enrico; Marco Malvezzi, Andrea; Massone, Giuseppe; Melich, Radek; Nicolosi, Piergiorgio; Noci, Giancarlo; Pancrazzi, Maurizio; Pelizzo, Maria G.; Poletto, Luca; Sasso, Clementina; Schühle, Udo; Solanki, Sami K.; Strachan, Leonard; Susino, Roberto; Tondello, Giuseppe; Uslenghi, Michela; Woch, Joachim; Abbo, Lucia; Bemporad, Alessandro; Casti, Marta; Dolei, Sergio; Grimani, Catia; Messerotti, Mauro; Ricci, Marco; Straus, Thomas; Telloni, Daniele; Zuppella, Paola; Auchère, Frederic; Bruno, Roberto; Ciaravella, Angela; Corso, Alain J.; Alvarez Copano, Miguel; Aznar Cuadrado, Regina; D'Amicis, Raffaella; Enge, Reiner; Gravina, Alessio; Jejčič, Sonja; Lamy, Philippe; Lanzafame, Alessandro; Meierdierks, Thimo; Papagiannaki, Ioanna; Peter, Hardi; Fernandez Rico, German; Giday Sertsu, Mewael; Staub, Jan; Tsinganos, Kanaris; Velli, Marco; Ventura, Rita; Verroi, Enrico; Vial, Jean-Claude; Vives, Sebastien; Volpicelli, Antonio; Werner, Stephan; Zerr, Andreas; Negri, Barbara; Castronuovo, Marco; Gabrielli, Alessandro; Bertacin, Roberto; Carpentiero, Rita; Natalucci, Silvia; Marliani, Filippo; Cesa, Marco; Laget, Philippe; Morea, Danilo; Pieraccini, Stefano; Radaelli, Paolo; Sandri, Paolo; Sarra, Paolo; Cesare, Stefano; Del Forno, Felice; Massa, Ernesto; Montabone, Mauro; Mottini, Sergio; Quattropani, Daniele; Schillaci, Tiziano; Boccardo, Roberto; Brando, Rosario; Pandi, Arianna; Baietto, Cristian; Bertone, Riccardo; Alvarez-Herrero, Alberto; García Parejo, Pilar; Cebollero, María; Amoruso, Mauro; Centonze, Vito Bibcode: 2020A&A...642A..10A Altcode: 2019arXiv191108462A
Aims: Metis is the first solar coronagraph designed for a space mission and is capable of performing simultaneous imaging of the off-limb solar corona in both visible and UV light. The observations obtained with Metis aboard the Solar Orbiter ESA-NASA observatory will enable us to diagnose, with unprecedented temporal coverage and spatial resolution, the structures and dynamics of the full corona in a square field of view (FoV) of ±2.9° in width, with an inner circular FoV at 1.6°, thus spanning the solar atmosphere from 1.7 R⊙ to about 9 R⊙, owing to the eccentricity of the spacecraft orbit. Due to the uniqueness of the Solar Orbiter mission profile, Metis will be able to observe the solar corona from a close (0.28 AU, at the closest perihelion) vantage point, achieving increasing out-of-ecliptic views with the increase of the orbit inclination over time. Moreover, observations near perihelion, during the phase of lower rotational velocity of the solar surface relative to the spacecraft, allow longer-term studies of the off-limb coronal features, thus finally disentangling their intrinsic evolution from effects due to solar rotation.
Methods: Thanks to a novel occultation design and a combination of a UV interference coating of the mirrors and a spectral bandpass filter, Metis images the solar corona simultaneously in the visible light band, between 580 and 640 nm, and in the UV H I Lyman-α line at 121.6 nm. The visible light channel also includes a broadband polarimeter able to observe the linearly polarised component of the K corona. The coronal images in both the UV H I Lyman-α and polarised visible light are obtained at high spatial resolution with a spatial scale down to about 2000 km and 15 000 km at perihelion, in the cases of the visible and UV light, respectively. A temporal resolution down to 1 s can be achieved when observing coronal fluctuations in visible light.
Results: The Metis measurements, obtained from different latitudes, will allow for complete characterisation of the main physical parameters and dynamics of the electron and neutral hydrogen/proton plasma components of the corona in the region where the solar wind undergoes the acceleration process and where the onset and initial propagation of coronal mass ejections (CMEs) take place. The near-Sun multi-wavelength coronal imaging performed with Metis, combined with the unique opportunities offered by the Solar Orbiter mission, can effectively address crucial issues of solar physics such as: the origin and heating/acceleration of the fast and slow solar wind streams; the origin, acceleration, and transport of the solar energetic particles; and the transient ejection of coronal mass and its evolution in the inner heliosphere, thus significantly improving our understanding of the region connecting the Sun to the heliosphere and of the processes generating and driving the solar wind and coronal mass ejections.
Conclusions: This paper presents the scientific objectives and requirements, the overall optical design of the Metis instrument, the thermo-mechanical design, and the processing and power unit; reports on the results of the campaigns dedicated to integration, alignment, and tests, and to the characterisation of the instrument performance; describes the operation concept, data handling, and software tools; and, finally, the diagnostic techniques to be applied to the data, as well as a brief description of the expected scientific products. The performance of the instrument measured during calibrations ensures that the scientific objectives of Metis can be pursued with success.

Metis website: http://metis.oato.inaf.it Title: 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: Probing the thermodynamic state of a Coronal Mass Ejection (CME) up to 1 AU Authors: Mishra, Wageesh; Wang, Yuming; Teriaca, Luca; Zhang, Jie; Chi, Yutian Bibcode: 2020FrASS...7....1M Altcode: Several earlier studies have attempted to estimate some of the thermodynamic properties of Coronal Mass Ejections (CMEs) either very close to the Sun or at 1 AU. In the present study, we attempt to extrapolate the internal thermodynamic properties of 2010 April 3 flux rope CME from near the Sun to 1 AU. For this purpose, we use the flux rope internal state (FRIS) model which is constrained by the kinematics of the CME. The kinematics of the CME is estimated using the STEREO/COR and HI observations in combination with drag based model (DBM) of CME propagation. Using the FRIS model, we focus on estimating the polytropic index of the CME plasma, heating/cooling rate, entropy changing rate, Lorentz force and thermal pressure force acting inside the CME. Our study finds that the polytropic index of the selected CME ranges between 1.7 to 1.9. This implies that the CME is in the heat-releasing state (i.e., entropy loss) throughout its journey from the Sun to Earth. The hindering role of Lorentz force and contributing role of thermal pressure force in governing the expansion of the CME is also identified. On comparing the estimated properties of the CME flux rope from the FRIS model with the in situ observations of the CME taken at 1 AU, we find relevant discrepancies between the results predicted by the model and the observations. We outline the approximations made in our study of probing the internal state of the CME during its heliospheric evolution and discuss the possible causes of the observed discrepancies. Title: The SPICE (Spectral Imaging of the Coronal Environment) Ultraviolet Imaging Spectrograph Investigation Authors: Hassler, D.; Auchere, F.; Carlsson, M.; Fludra, A.; Giunta, A. S.; Mueller, D.; Peter, H.; Parenti, S.; Teriaca, L.; Fredvik, T. Bibcode: 2019AGUFMSH24A..02H Altcode: One of the primary objectives of the Solar Orbiter mission is to link remote sensing observations of the solar surface structures with in-situ observations of solar wind streams. The SPICE (Spectral Imaging of the Coronal Environment) instrument will characterize the plasma properties of regions near the Sun to directly compare with in-situ measurements from both Solar Orbiter & Parker Solar Probe. Specifically, SPICE will map outflow velocities of surface features to solar wind structures with similar composition (FIP, M/q) measured in-situ by the SWA/HIS instrument on Solar Orbiter. These observations will help discriminate models of solar wind origin by matching composition signatures in solar wind streams to surface feature composition, and discriminate physical processes that inject material from closed structures into solar wind streams.

This presentation will provide an overview of the SPICE investigation, including science & measurement objective, instrument design, capabilities and performance as measured during calibration prior to delivery to the Solar Orbiter spacecraft. The presentation will also provide a description of the operations concept and data processing during the mission. Title: Concept study of Solar-C_EUVST optical design Authors: Kawate, Tomoko; Shimizu, Toshifumi; Imada, Shinsuke; Tsuzuki, Toshihiro; Katsukawa, Yukio; Hara, Hirohisa; Suematsu, Yoshinori; Ichimoto, Kiyoshi; Warren, Harry; Teriaca, Luca; Korendyke, Clarence M.; Brown, Charles Bibcode: 2019SPIE11118E..1NK Altcode: The main characteristics of Solar-C_EUVST are the high temporal and high spatial resolutions over a wide temperature coverage. In order to realize the instrument for meeting these scientific requirements under size constraints given by the JAXA Epsilon vehicle, we examined four-dimensional optical parameter space of possible solutions of geometrical optical parameters such as mirror diameter, focal length, grating magnification, and so on. As a result, we have identified the solution space that meets the EUVST science objectives and rocket envelope requirements. A single solution was selected and used to define the initial optical parameters for the concept study of the baseline architecture for defining the mission concept. For this solution, we optimized the grating and geometrical parameters by ray tracing of the Zemax software. Consequently, we found an optics system that fulfills the requirement for a 0.4" angular resolution over a field of view of 100" (including margins) covering spectral ranges of 170-215, 463-542, 557-637, 690-850, 925-1085, and 1115-1275 A. This design achieves an effective area 10 times larger than the Extreme-ultraviolet Imaging Spectrometer onboard the Hinode satellite, and will provide seamless observations of 4.2-7.2 log(K) plasmas for the first time. Tolerance analyses were performed based on the optical design, and the moving range and step resolution of focus mechanisms were identified. In the presentation, we describe the derivation of the solution space, optimization of the optical parameters, and show the results of ray tracing and tolerance analyses. Title: The Solar-C_EUVST mission Authors: Shimizu, Toshifumi; Imada, Shinsuke; Kawate, Tomoko; Ichimoto, Kiyoshi; Suematsu, Yoshinori; Hara, Hirohisa; Katsukawa, Yukio; Kubo, Masahito; Toriumi, Shin; Watanabe, Tetsuya; Yokoyama, Takaaki; Korendyke, Clarence M.; Warren, Harry P.; Tarbell, Ted; De Pontieu, Bart; Teriaca, Luca; Schühle, Udo H.; Solanki, Sami; Harra, Louise K.; Matthews, Sarah; Fludra, A.; Auchère, F.; Andretta, V.; Naletto, G.; Zhukov, A. Bibcode: 2019SPIE11118E..07S Altcode: Solar-C EUVST (EUV High-Throughput Spectroscopic Telescope) is a solar physics mission concept that was selected as a candidate for JAXA competitive M-class missions in July 2018. The onboard science instrument, EUVST, is an EUV spectrometer with slit-jaw imaging system that will simultaneously observe the solar atmosphere from the photosphere/chromosphere up to the corona with seamless temperature coverage, high spatial resolution, and high throughput for the first time. The mission is designed to provide a conclusive answer to the most fundamental questions in solar physics: how fundamental processes lead to the formation of the solar atmosphere and the solar wind, and how the solar atmosphere becomes unstable, releasing the energy that drives solar flares and eruptions. The entire instrument structure and the primary mirror assembly with scanning and tip-tilt fine pointing capability for the EUVST are being developed in Japan, with spectrograph and slit-jaw imaging hardware and science contributions from US and European countries. The mission will be launched and installed in a sun-synchronous polar orbit by a JAXA Epsilon vehicle in 2025. ISAS/JAXA coordinates the conceptual study activities during the current mission definition phase in collaboration with NAOJ and other universities. The team is currently working towards the JAXA final down-selection expected at the end of 2019, with strong support from US and European colleagues. The paper provides an overall description of the mission concept, key technologies, and the latest status. Title: Optical performance of the Metis coronagraph on the Solar Orbiter ESA mission Authors: Frassetto, Fabio; Da Deppo, Vania; Zuppella, Paola; Romoli, Marco; Fineschi, Silvano; Antonucci, Ester; Nicolini, Giana; Naletto, Giampiero; Nicolosi, Piergiorgio; Spadaro, Daniele; Andretta, Vincenzo; Castronuovo, Marco; Casti, Marta; Capobianco, Gerardo; Massone, Giuseppe; Susino, Roberto; Landini, Federico; Pancrazzi, Maurizio; Teriaca, Luca; Schühle, Udo; Heerlein, Klaus; Uslenghi, Michela Bibcode: 2019SPIE11180E..6YF Altcode: The Metis coronagraph aboard the Solar Orbiter ESA spacecraft is expected to provide new insights into the solar dynamics. In detail, it is designed to address three main questions: the energy deposition mechanism at the poles (where the fast wind is originated), the source of the slow wind at lower altitude, and how the global corona evolves, in particular in relation to the huge plasma ejections that occasionally are produced. To obtain the required optical performance, not only the Metis optical design has been highly optimized, but the alignment procedure has also been subjected to an accurate evaluation in order to fulfill the integration specifications. The telescope assembling sequence has been constructed considering all the subsystems manufacturing, alignment and integration tolerances. The performance verification activity is an important milestone in the instrument characterization and the obtained results will assure the fulfillment of the science requirements for its operation in space. The entire alignment and verification phase has been performed by the Metis team in collaboration with Thales Alenia Space Torino and took place in ALTEC (Turin) at the Optical Payload System Facility using the Space Optics Calibration Chamber infrastructure, a vacuum chamber especially built and tested for the alignment and calibration of the Metis coronagraph, and suitable for tests of future payloads. The goal of the alignment, integration, verification and calibration processes is to measure the parameters of the telescope, and the characteristics of the two Metis channels: visible and ultraviolet. They work in parallel thanks to the peculiar optical layout. The focusing and alignment performance of the two channels must be well understood, and the results need to be easily compared to the requirements. For this, a dedicated illumination method, with both channels fed by the same source, has been developed; and a procedure to perform a simultaneous through focus analysis has been adopted. In this paper the final optical performance achieved by Metis is reported and commented. Title: Alignment procedure for the Gregorian telescope of the Metis coronagraph for the Solar Orbiter ESA mission Authors: Da Deppo, Vania; Mottini, Sergio; Naletto, Giampiero; Frassetto, Fabio; Zuppella, Paola; Sertsu, Mewael G.; Romoli, Marco; Fineschi, Silvano; Antonucci, Ester; Nicolini, Gianalfredo; Nicolosi, Piergiorgio; Spadaro, Daniele; Andretta, Vincenzo; Castronuovo, Marco; Casti, Marta; Capobianco, Gerardo; Massone, Giuseppe; Susino, Roberto; Landini, Federico; Pancrazzi, Maurizio; Casini, Chiara; Teriaca, Luca; Uslenghi, Michela Bibcode: 2019SPIE11180E..76D Altcode: Metis is a solar coronagraph mounted on-board the Solar Orbiter ESA spacecraft. Solar Orbiter is scheduled for launch in February 2020 and it is dedicated to study the solar and heliospheric physics from a privileged close and inclined orbit around the Sun. Perihelion passages with a minimum distance of 0.28 AU are foreseen. Metis features two channels to image the solar corona in two different spectral bands: in the HI Lyman at 121.6 nm, and in the polarized visible light band (580 - 640 nm). Metis is a solar coronagraph adopting an "inverted occulted" configuration. The inverted external occulter (IEO) is a circular aperture followed by a spherical mirror which back rejects the disk light. The reflected disk light exits the instrument through the IEO aperture itself, while the passing coronal light is collected by the Metis telescope. Common to both channels, the Gregorian on-axis telescope is centrally occulted and both the primary and the secondary mirror have annular shape. Classic alignment methods adopted for on-axis telescope cannot be used, since the on-axis field is not available. A novel and ad hoc alignment set-up has been developed for the telescope alignment. An auxiliary visible optical ground support equipment source has been conceived for the telescope alignment. It is made up by four collimated beams inclined and dimensioned to illuminate different sections of the annular primary mirror without being vignetted by other optical or mechanical elements of the instrument. Title: Metis/Solar Orbiter polarimetric visible light channel calibration Authors: Casti, M.; Fineschi, S.; Capobianco, G.; Romoli, M.; Antonucci, E.; Nicolini, G.; Naletto, G.; Nicolosi, P.; Spadaro, D.; Andretta, V.; Castronuovo, M.; Massone, G.; Susino, R.; Da Deppo, V.; Frassetto, F.; Landini, F.; Pancrazzi, M.; Teriaca, L.; Uslenghi, M. Bibcode: 2019SPIE11180E..3CC Altcode: Metis is the solar coronagraph of the ESA mission Solar Orbiter. For the first time, Metis will acquire simultaneous images of the solar corona in linearly polarized, broadband visible light (580-640 nm) and in the narrow-band HI Ly-α line (121.6 nm). The visible light path includes a polarimeter, designed to observe and analyse the K-corona linearly polarized by Thomson scattering. The polarimeter comprises a liquid crystal Polarization Modulation Package (PMP) together with a quarter-wave retarder and a linear polarizer. The Metis PMP consists of two Anti-Parallel Nematic Liquid Crystal Variable Retarders (LCVRs) with their fast axis parallel with respect to each other and a pre-tilted angle of the molecules in opposite direction. This configuration results in an instrumental wide field of view (+/-7°). The LCVRs provide an electro-optical modulation of the input polarized light by applying an electric field to the liquid crystal molecules inside the cells. A given optical retardance can be induced in the LCVRs by selecting a suitable voltage value. This paper reports the polarimetric characterization of the Visible-light channel for the Metis/Solar Orbiter coronagraph. The retardance-to-voltage calibration of the electro-optical polarimeter was characterized over the entire field of view of the coronagraph yielding a complete "polarimetric flat-field" of the Metis Visible-light channel. Title: Stray light calibration for the Solar Orbiter/Metis solar coronagraph Authors: Landini, F.; Romoli, M.; Fineschi, S.; Casini, C.; Baccani, C.; Antonucci, E.; Nicolini, G.; Naletto, G.; Nicolosi, P.; Spadaro, D.; Andretta, V.; Castronuovo, M.; Casti, M.; Capobianco, G.; Massone, G.; Susino, R.; Da Deppo, V.; Frassetto, F.; Pancrazzi, M.; Teriaca, L.; Schuehle, U.; Heerlein, K.; Uslenghi, M. Bibcode: 2019SPIE11180E..2IL Altcode: The Solar Orbiter/Metis visible and UV solar coronagraph redefines the concept of external occultation in solar coronagraphy. Classical externally occulted coronagraphs are characterized by an occulter in front of the telescope entrance aperture. Solar Orbiter will approach the Sun down to 0.28 AU: in order to reduce the thermal load, the Metis design switches the positions of the entrance aperture and the external occulter thus achieving what is called the inverted external occultation. The inverted external occulter (IEO) consists of a circular aperture on the Solar Orbiter thermal shield that acts as coronagraph entrance pupil. A spherical mirror, located 800 mm behind the IEO, back rejects the disklight through the IEO itself. To pursue the goal of maximizing the reduction of the stray light level on the focal plane, an optimization of the IEO shape was implemented. The stray light calibration was performed in a clean environment in front of the OPSys solar disk divergence simulator (at ALTEC, in Torino, Italy), which is able to emulate different heliocentric distances. Ground calibrations were a unique opportunity to map the Metis stray light level thanks to a pure solar disk simulator without the solar corona. The stray light calibration was limited to the visible light case, being the most stringent. This work is focused on the description of the laboratory facility that was used to perform the stray light calibration and on the calibration results. Title: Broadband EUV/FUV mirror coatings for a solar spectrograph mission Authors: Teriaca, Luca; Feigl, Torsten; Schühle, Udo Bibcode: 2018SPIE10699E..2YT Altcode: As it is rich in spectral lines emitted by plasma between 10000 K and 20 MK, the vacuum ultraviolet (VUV - 17 to 200 nm) solar spectrum is extremely valuable for instruments that study the physics of the solar atmosphere. We present multilayer coatings with simultaneous broadband reflectance in the two spectral ranges of 16.9 nm to 21.5 nm and 46.3 nm to 127.5 nm. The coatings are based on Mo/Si multilayers with a thin capping layer of boron carbide (B4C). Samples were produced and their reflectance measured. Their performance in terms of resistance to high temperatures and low micro-roughness was also assessed by measurement. Our study shows that a coating with the characteristics required by next generation spectrometers for studies of the solar atmosphere is feasible. Title: The solar orbiter Metis and EUI intensified CMOS-APS detectors: concept, main characteristics, and performance Authors: Schühle, Udo; Teriaca, Luca; Aznar Cuadrado, Regina; Heerlein, Klaus; Uslenghi, Michela; Werner, Stephan Bibcode: 2018SPIE10699E..34S Altcode: Two instruments aboard the Solar Orbiter mission, the Extreme Ultraviolet Imager and the Metis coronagraph, are using cameras of similar design to obtain images in the Lyman alpha line of hydrogen at 121.6 nm. Each of these cameras is based on an APS sensor used as readout of a single microchannel plate intensifier unit whose output current is converted into visible light photons through a phosphor screen. Before integration on the respective instruments, both detector's flight models have been characterized and calibrated. In this paper, we describe the two camera systems, the results of qualification tests, and report their performance characteristics. Title: The EUI flight instrument of Solar Orbiter: from optical alignment to end-to-end calibration Authors: Halain, J. -P.; Renotte, E.; Auchère, F.; Berghmans, D.; Delmotte, F.; Harra, L.; Schmutz, W.; Schühle, U.; Aznar Cuadrado, R.; Dumesnil, C.; Gyo, M.; Kennedy, T.; Verbeeck, C.; Barbay, J.; Giordanengo, B.; Gissot, S.; Gottwald, A.; Heerlein, K.; Hellin, M. -L.; Hermans, A.; Hervier, V.; Jacques, L.; Laubis, C.; Mazzoli, A.; Meining, S.; Mercier, R.; Philippon, A.; Roose, S.; Rossi, L.; Scholze, F.; Smith, P.; Teriaca, L.; Zhang, X.; Rochus, P. Bibcode: 2018SPIE10699E..0HH Altcode: The Extreme Ultraviolet Imager (EUI) instrument for the Solar Orbiter mission will image the solar corona in the extreme ultraviolet (17.1 nm and 30.4 nm) and in the vacuum ultraviolet (121.6 nm) spectral ranges. The development of the EUI instrument has been successfully completed with the optical alignment of its three channels' telescope, the thermal and mechanical environmental verification, the electrical and software validations, and an end-toend on-ground calibration of the two-units' flight instrument at the operating wavelengths. The instrument has been delivered and installed on the Solar Orbiter spacecraft, which is now undergoing all preparatory activities before launch. Title: METIS, the Multi Element Telescope for Imaging and Spectroscopy: an instrument proposed for the solar orbiter mission Authors: Antonucci, E.; Andretta, V.; Cesare, S.; Ciaravella, A.; Doschek, G.; Fineschi, S.; Giordano, S.; Lamy, P.; Moses, D.; Naletto, G.; Newmark, J.; Poletto, L.; Romoli, M.; Solanki, S.; Spadaro, D.; Teriaca, L.; Zangrilli, L. Bibcode: 2017SPIE10566E..0LA Altcode: METIS, the Multi Element Telescope for Imaging and Spectroscopy, is an instrument proposed to the European Space Agency to be part of the payload of the Solar Orbiter mission. The instrument design has been conceived for performing extreme ultraviolet (EUV) spectroscopy both on the solar disk and off-limb, and near-Sun coronagraphy and spectroscopy. The proposed instrument suite consists of three different interconnected elements, COR, EUS and SOCS, sharing the same optical bench, electronics, and S/C heat shield aperture. COR is a visible-EUV multiband coronagraph based on a classical externally occulted design. EUS is the component of the METIS EUV disk spectrometer which includes the telescope and all the related mechanisms. Finally, SOCS is the METIS spectroscopic component including the dispersive system and the detectors. The capability of inserting a small telescope collecting coronal light has been added to perform also EUV coronal spectroscopy. METIS can simultaneously image the visible and ultraviolet emission of the solar corona and diagnose, with unprecedented temporal coverage and space resolution the structure and dynamics of the full corona in the range from 1.2 to 3.0 (1.6 to 4.1) solar radii (R⊙, measured from Sun centre) at minimum (maximum) perihelion during the nominal mission. It can also perform spectroscopic observations of the solar disk and out to 1.4 R⊙ within the 50-150 nm spectral region, and of the geo-effective coronal region 1.7-2.7 R⊙ within the 30-125 nm spectral band. 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: Spectroscopy of Very Hot Plasma in Non-flaring Parts of a Solar Limb Active Region: Spatial and Temporal Properties Authors: Parenti, Susanna; del Zanna, Giulio; Petralia, Antonino; Reale, Fabio; Teriaca, Luca; Testa, Paola; Mason, Helen E. Bibcode: 2017ApJ...846...25P Altcode: 2017arXiv170708445P In this work we investigate the thermal structure of an off-limb active region (AR) in various non-flaring areas, as it provides key information on the way these structures are heated. In particular, we concentrate on the very hot component (> 3 {MK}) as it is a crucial element to distinguish between different heating mechanisms. We present an analysis using Fe and Ca emission lines from both the Solar Ultraviolet Measurement of Emitted Radiation (SUMER) on board the Solar and Heliospheric Observatory (SOHO) and the EUV Imaging Spectrometer (EIS) on board Hinode. A data set covering all ionization stages from Fe x to Fe xix has been used for the thermal analysis (both differential emission measure and emission measure, EM). Ca xiv is used for the SUMER-EIS radiometric cross calibration. We show that the very hot plasma is present and persistent almost everywhere in the core of the limb AR. The off-limb AR is clearly structured in Fe xviii. Almost everywhere, the EM analysis reveals plasma at 10 MK (visible in Fe xix emission), which is down to 0.1% of EM of the main 3 {MK} plasma. We estimate the power-law index of the hot tail of the EM to be between -8.5 and -4.4. However, the question about the possible existence of a small minor peak at around 10 {MK} remains open. The absence in some part of the AR of the Fe xix and Fe xxiii lines (which fall into our spectral range) enables us to determine an upper limit on the EM at these temperatures. Our results include a new Ca xiv 943.59 Å atomic model. Title: Characterization of the UV detector of Solar Orbiter/Metis Authors: Uslenghi, Michela; Schühle, Udo H.; Teriaca, Luca; Heerlein, Klaus; Werner, Stephan Bibcode: 2017SPIE10397E..1KU Altcode: Metis, one of the instruments of the ESA mission Solar Orbiter (to be launched in February 2019), is a coronograph able to perform broadband polarization imaging in the visible range (580-640 nm), and narrow band imaging in UV (HI Lyman-α 121.6 nm) . The detector of the UV channel is an intensified camera, based on a Star-1000 rad-hard CMOS APS coupled via a 2:1 fiber optic taper to a single stage Microchannel Plate intensifier, sealed with an entrance MgF2 window and provided with an opaque KBr photocathode. Before integration in the instrument, the UVDA (UV Detector Assembly) Flight Model has been characterized at the MPS laboratory and calibrated in the UV range using the detector calibration beamline of the Metrology Light Source synchrotron of the Physikalisch-Technische Bundesanstalt (PTB). Linearity, spectral calibration, and response uniformity at 121.6 nm have been measured. Preliminary results are reported in this paper. Title: The SPICE Spectral Imager on Solar Orbiter: Linking the Sun to the Heliosphere Authors: Fludra, Andrzej; Haberreiter, Margit; Peter, Hardi; Vial, Jean-Claude; Harrison, Richard; Parenti, Susanna; Innes, Davina; Schmutz, Werner; Buchlin, Eric; Chamberlin, Phillip; Thompson, William; Gabriel, Alan; Morris, Nigel; Caldwell, Martin; Auchere, Frederic; Curdt, Werner; Teriaca, Luca; Hassler, Donald M.; DeForest, Craig; Hansteen, Viggo; Carlsson, Mats; Philippon, Anne; Janvier, Miho; Wimmer-Schweingruber, Robert; Griffin, Douglas; Davila, Joseph; Giunta, Alessandra; Waltham, Nick; Eccleston, Paul; Gottwald, Alexander; Klein, Roman; Hanley, John; Walls, Buddy; Howe, Chris; Schuehle, Udo Bibcode: 2016cosp...41E.607F Altcode: The SPICE (Spectral Imaging of the Coronal Environment) instrument is one of the key remote sensing instruments onboard the upcoming Solar Orbiter Mission. SPICE has been designed to contribute to the science goals of the mission by investigating the source regions of outflows and ejection processes which link the solar surface and corona to the heliosphere. In particular, SPICE will provide quantitative information on the physical state and composition of the solar atmosphere plasma. For example, SPICE will access relative abundances of ions to study the origin and the spatial/temporal variations of the 'First Ionization Potential effect', which are key signatures to trace the solar wind and plasma ejections paths within the heliosphere. Here we will present the instrument and its performance capability to attain the scientific requirements. We will also discuss how different observation modes can be chosen to obtain the best science results during the different orbits of the mission. To maximize the scientific return of the instrument, the SPICE team is working to optimize the instrument operations, and to facilitate the data access and their exploitation. Title: Solar abundances with the SPICE spectral imager on Solar Orbiter Authors: Giunta, Alessandra; Haberreiter, Margit; Peter, Hardi; Vial, Jean-Claude; Harrison, Richard; Parenti, Susanna; Innes, Davina; Schmutz, Werner; Buchlin, Eric; Chamberlin, Phillip; Thompson, William; Bocchialini, Karine; Gabriel, Alan; Morris, Nigel; Caldwell, Martin; Auchere, Frederic; Curdt, Werner; Teriaca, Luca; Hassler, Donald M.; DeForest, Craig; Hansteen, Viggo; Carlsson, Mats; Philippon, Anne; Janvier, Miho; Wimmer-Schweingruber, Robert; Griffin, Douglas; Baudin, Frederic; Davila, Joseph; Fludra, Andrzej; Waltham, Nick; Eccleston, Paul; Gottwald, Alexander; Klein, Roman; Hanley, John; Walls, Buddy; Howe, Chris; Schuehle, Udo; Gyo, Manfred; Pfiffner, Dany Bibcode: 2016cosp...41E.681G Altcode: Elemental composition of the solar atmosphere and in particular abundance bias of low and high First Ionization Potential (FIP) elements are a key tracer of the source regions of the solar wind. These abundances and their spatio-temporal variations, as well as the other plasma parameters , will be derived by the SPICE (Spectral Imaging of the Coronal Environment) EUV spectral imager on the upcoming Solar Orbiter mission. SPICE is designed to provide spectroheliograms (spectral images) using a core set of emission lines arising from ions of both low-FIP and high-FIP elements. These lines are formed over a wide range of temperatures, enabling the analysis of the different layers of the solar atmosphere. SPICE will use these spectroheliograms to produce dynamic composition maps of the solar atmosphere to be compared to in-situ measurements of the solar wind composition of the same elements (i.e. O, Ne, Mg, Fe). This will provide a tool to study the connectivity between the spacecraft (the Heliosphere) and the Sun. We will discuss the SPICE capabilities for such composition measurements. Title: Propagating disturbances along fan-like coronal loops in an active region Authors: Mandal, Sudip; Samanta, Tanmoy; Banerjee, Dipankar; Krishna Prasad, S.; Teriaca, Luca Bibcode: 2015RAA....15.1832M Altcode: 2015arXiv150504710M Propagating disturbances are often observed in active region fan-like coronal loops. They were thought to be due to slow mode magnetohydrodynamic waves based on some of the observed properties. However, recent studies involving spectroscopy indicate that they could be due to high speed quasi-periodic upflows which are difficult to distinguish from upward propagating slow waves. In this context, we have studied a fan loop structure in the active region AR 11465 using simultaneous spectroscopic and imaging observations from the Extreme Ultraviolet Imaging Spectrometer onboard Hinode and Atmospheric Imaging Assembly onboard Solar Dynamics Observatory. Analysis of the data shows significant oscillations at different locations. We explore the variations in different line parameters to determine whether the waves or flows could cause these oscillations to improve the current understanding of the nature of these disturbances. Title: Solar extreme ultraviolet variability of the quiet Sun Authors: Shakeri, F.; Teriaca, L.; Solanki, S. K. Bibcode: 2015A&A...581A..51S Altcode: 2015arXiv150705786S The last solar minimum has been unusually quiet compared to the previous minima (since space-based radiometric measurements are available). The Sun's magnetic flux was substantially lower during this minimum. Some studies also show that the total solar irradiance during the minimum after cycle 23 may have dropped below the values known from the two minima prior to that. For chromospheric and coronal radiation, the situation is less clear-cut. The Sun's 10.7 cm flux shows a decrease of ~4% during the solar minimum in 2008 compared to the previous minimum, but Ca ii K does not. Here we consider additional wavelengths in the extreme ultraviolet (EUV), specifically transitions of He i at 584.3 Å and O v at 629.7 Å, of which the CDS spectrometer aboard SOHO has been taking regular scans along the solar central meridian since 1996. We analysed this unique dataset to verify if and how the radiance distribution undergoes measurable variations between cycle minima. To achieve this aim we determined the radiance distribution of quiet areas around the Sun centre. Concentrating on the last two solar minima, we found out that there is very little variation in the radiance distribution of the chromospheric spectral line He i between these minima. The same analysis shows a modest, although significant, 4% variation in the radiance distribution of the TR spectral line O v. These results are comparable to those obtained by earlier studies employing other spectral features, and they confirm that chromospheric indices display a small variation, whereas in the transition region a more significant reduction of the brighter features is visible. Title: Scattered Lyman-α radiation of comet 2012/S1 (ISON) observed by SUMER/SOHO Authors: Curdt, W.; Boehnhardt, H.; Vincent, J. -B.; Solanki, S. K.; Schühle, U.; Teriaca, L. Bibcode: 2014A&A...567L...1C Altcode: 2014arXiv1406.4343C During its sungrazing perihelion passage, comet ISON appeared in the field of view of the SUMER spectrometer and allowed unique observations at far-ultraviolet wavelengths with high spatial and temporal resolution. We report results of these observations completed on November 28, 2013, when the comet was only 2.82 Rʘ away from the Sun. Our data show the arrow-shaped dust tail in Ly-α emission trailing behind the predicted position of the nucleus, but offset from the trajectory. We interpret the emission as sunlight that is scattered at μm-sized dust particles. We modeled the dust emission and dynamics to reproduce the appearance of the tail. We were unable to detect any signature of cometary gas or plasma around the expected position of the nucleus and conclude that the outgassing processes must have stopped before the observation started. Moreover, the model we used to reproduce the observed dust tail needs a sharp fall-off of the dust production hours before perihelion transit. We compare the radiances of the disk and the dust tail for an estimate of the dust column density and tail mass. Title: In-flight UV and polarized-VL radiometric calibrations of the solar orbiter/METIS imaging coronagraph Authors: Focardi, M.; Capobianco, G.; Andretta, V.; Sasso, C.; Romoli, M.; Landini, F.; Fineschi, S.; Pancrazzi, M.; Bemporad, A.; Nicolini, G.; Pucci, S.; Uslenghi, M.; Naletto, G.; Nicolosi, P.; Spadaro, D.; Teriaca, L.; SchuÌhle, U. H.; Antonucci, E. Bibcode: 2014SPIE.9144E..09F Altcode: METIS is an innovative inverted occulted solar coronagraph capable of obtaining for the first time simultaneous imaging of the full corona in linearly polarized visible-light (580-640 nm) and narrow-band (+/- 10 nm) ultraviolet H I Ly-α (121.6 nm). It has been selected to fly aboard the Solar Orbiter1 spacecraft, whose launch is foreseen in July 2017. Thanks to its own capabilities and exploiting the peculiar opportunities offered by the Solar Orbiter planned orbit, METIS will address some of the still open issues in understanding the physical processes in the corona and inner heliosphere. The Solar Orbiter Nominal Mission Phase (NMP) will be characterized by three scientific observing windows per orbit and METIS will perform at least one in-flight calibration per observing window. The two imaging channels of METIS will be calibrated on ground and periodically checked, verified and re-calibrated in-flight. In particular, radiometric calibration images will be needed to determine the absolute brightness of the solar corona. For UV radiometric calibration a set of targets is represented by continuum-emitting early type bright stars (e.g. A and B spectral types) whose photospheres produce a bright far-ultraviolet continuum spectrum stable over long timescales. These stars represent an important reference standard not only for METIS in-flight calibrations but also for other Solar Orbiter instruments and they will be crucial for instruments cross-calibrations as well. For VL radiometric calibration, a set of linearly polarized stars will be used. These targets shall have a minimum degree of linear polarization (DoLP > 5%) and a detectable magnitude, compatible with the instrument integration times constrained by the desired S/N ratio and the characteristics of the spacecraft orbit dynamics. Title: Scattered Lyman-alpha radiation of comet 2012/S1 (ISON) observed by SUMER/SOHO Authors: Curdt, W.; Boehnhardt, H.; Germerott, D.; Schuehle, U.; Solanki, S.; Teriaca, L.; Vincent, J. Bibcode: 2014acm..conf..119C Altcode: During its recent perihelion passage, comet ISON came so close to the Sun that it appeared in the field of view (FOV) of the SUMER spectrometer on SOHO and allowed unique observations at far-UV wavelengths with high spatial and temporal resolution. We report results of these observations completed during the comet's encounter with the Sun on November 28.75, 2013. Our data show the dust tail trailing behind the predicted position of the nucleus seen in Lyman-alpha emission as light from the solar disk that is scattered by micron-sized dust particles. The arrow-shaped tail is offset from the trajectory and not aligned with it. We model the dust emission and dynamics to reproduce the appearance of the tail. We could not detect any signature of cometary gas or plasma around the expected position of the nucleus and conclude that the out-gassing processes must have stopped before the comet entered our FOV. Also the model we used to reproduce the observed dust tail needs a sharp fall-off of the dust production hours before perihelion. We compare the radiance of the dust tail to the Lyman-alpha emission of the disk for an estimate of the dust column density. After observing 18 years mostly solar targets, this was the first time that SUMER completed spectroscopic observations of a comet. Title: Hardware and software architecture on board solar orbiter/METIS: an update Authors: Pancrazzi, M.; Focardi, M.; Nicolini, G.; Andretta, V.; Uslenghi, M.; Magli, E.; Ricci, M.; Bemporad, A.; Spadaro, D.; Landini, F.; Romoli, M.; Antonucci, E.; Fineschi, S.; Naletto, G.; Nicolosi, P.; Teriaca, L. Bibcode: 2014SPIE.9144E..3FP Altcode: METIS, is one of the ten instruments selected to be part of the Solar Orbiter payload; it is a coronagraph that will investigate the inner part of the heliosphere performing imaging in the visible band and in the hydrogen Lyman α line @ 121.6 nm. METIS has recently undergone throughout a revision to simplify the instrument design. This paper will provide an overview of the updated hardware and software design of the coronagraph as presented at the Instrument Delta-Preliminary Design Review occurred in April 2014. The current configuration foresees two detectors, an Intensified APS for the UV channel and an APS for the visible light equipped with a Liquid Crystal Variable Retarder (LCVR) plate to perform broadband visible polarimetry. Each detector has a proximity electronics generating the control and readout signals for the sensor but the operations of the two devices are in charge of a centralized unit, the METIS Processing and Power Unit (MPPU). The MPPU operates the remaining electrical subsystems supplying them with power and providing on board storage and processing capabilities. Its design foresees the redundancy of the most critical parts, thus mitigating the effects of possible failures of the electronics subsystems. The central monitoring unit is also in charge of providing the communication with the S/C, handling the telemetry and telecommand exchange with the platform. The data acquired by the detectors shall undergo through a preliminary on-board processing to maximize the scientific return and to provide the necessary information to validate the results on ground. Operations as images summing, compression and cosmic rays monitoring and removal will be fundamental not only to mitigate the effects of the main sources of noise on the acquired data, but also to maximize the data volume to be transferred to the spacecraft in order to fully exploit the limited bandwidth telemetry downlink. Finally, being Solar Orbiter a deep-space mission, some METIS procedures have been designed to provide the instrument an efficient autonomous behavior in case of an immediate reaction is required as for the arising of transient events or the occurrence of safety hazards conditions. Title: The SUMER Data in the SOHO Archive Authors: Curdt, W.; Germerott, D.; Wilhelm, K.; Schühle, U.; Teriaca, L.; Innes, D.; Bocchialini, K.; Lemaire, P. Bibcode: 2014SoPh..289.2345C Altcode: 2013arXiv1309.1314C We have released an archive of all observational data of the VUV spectrometer Solar Ultraviolet Measurements of Emitted Radiation (SUMER) on SOHO that have been acquired until now. The operational phase started with `first light' observations on 27 January 1996 and will end in 2014. Future data will be added to the archive when they become available. The archive consists of a set of raw data (Level 0) and a set of data that are processed and calibrated to the best knowledge we have today (Level 1). This communication describes step by step the data acquisition and processing that has been applied in an automated manner to build the archive. It summarizes the expertise and insights into the scientific use of SUMER spectra that has accumulated over the years. It also indicates possibilities for further enhancement of the data quality. With this article we intend to convey our own understanding of the instrument performance to the scientific community and to introduce the new, standard FITS-format database. Title: Characteristics of polar coronal hole jets Authors: Chandrashekhar, K.; Bemporad, A.; Banerjee, D.; Gupta, G. R.; Teriaca, L. Bibcode: 2014A&A...561A.104C Altcode: 2013arXiv1310.8106C Context. High spatial- and temporal-resolution images of coronal hole regions show a dynamical environment where mass flows and jets are frequently observed. These jets are believed to be important for the coronal heating and the acceleration of the fast solar wind.
Aims: We studied the dynamics of two jets seen in a polar coronal hole with a combination of imaging from EIS and XRT onboard Hinode. We observed drift motions related to the evolution and formation of these small-scale jets, which we tried to model as well.
Methods: Stack plots were used to find the drift and flow speeds of the jets. A toymodel was developed by assuming that the observed jet is generated by a sequence of single reconnection events where single unresolved blobs of plasma are ejected along open field lines, then expand and fall back along the same path, following a simple ballistic motion.
Results: We found observational evidence that supports the idea that polar jets are very likely produced by multiple small-scale reconnections occurring at different times in different locations. These eject plasma blobs that flow up and down with a motion very similar to a simple ballistic motion. The associated drift speed of the first jet is estimated to be ≈27 km s-1. The average outward speed of the first jet is ≈171 km s-1, well below the escape speed, hence if simple ballistic motion is considered, the plasma will not escape the Sun. The second jet was observed in the south polar coronal hole with three XRT filters, namely, C-poly, Al-poly, and Al-mesh filters. Many small-scale (≈3″-5″) fast (≈200-300 km s-1) ejections of plasma were observed on the same day; they propagated outwards. We observed that the stronger jet drifted at all altitudes along the jet with the same drift speed of ≃7 km s-1. We also observed that the bright point associated with the first jet is a part of sigmoid structure. The time of appearance of the sigmoid and that of the ejection of plasma from the bright point suggest that the sigmoid is the progenitor of the jet.
Conclusions: The enhancement in the light curves of low-temperature EIS lines in the later phase of the jet lifetime and the shape of the jet's stack plots suggests that the jet material falls back, and most likely cools down. To further support this conclusion, the observed drifts were interpreted within a scenario where reconnection progressively shifts along a magnetic structure, leading to the sequential appearance of jets of about the same size and physical characteristics. On this basis, we also propose a simple qualitative model that mimics the observations.

Movies 1-3 are available in electronic form at http://www.aanda.org Title: Quiet Sun Explosive Events: Jets, Splashes, and Eruptions Authors: Innes, D. E.; Teriaca, L. Bibcode: 2013SoPh..282..453I Altcode: 2012arXiv1210.7667I Explosive events appear as broad non-Gaussian wings in the line profiles of small transition-region phenomena. Images from the Solar Dynamics Observatory (SDO) give a first view of the plasma dynamics at the sites of explosive events seen simultaneously in O VI spectra of a region of quiet Sun, taken with the ultraviolet spectrometer Solar Ultraviolet Measurements of Emitted Radiation (SUMER) onboard the Solar and Heliospheric Observatory (SOHO). Distinct event bursts were seen either at the junction of supergranular network cells or near emerging flux. Three are described in the context of their surrounding transition region (304 Å) and coronal (171 Å) activity. One showed plasma ejections from an isolated pair of sites, with a time lag of 50 seconds between events. At the site where the later explosive event was seen, the extreme ultraviolet (EUV) images show a hot core surrounded by a small, expanding ring of chromospheric emission, which we interpret as a "splash." The second explosive-event burst was related to flux cancellation, inferred from Helioseismic and Magnetic Imager (HMI) magnetograms, and a coronal dimming surrounded by a ring of bright EUV emission with explosive events at positions where the spectrometer slit crossed the bright ring. The third series of events occurred at the base of a slow, small coronal mass ejection (mini-CME). All events studied here imply jet-like flows probably triggered by magnetic reconnection at supergranular junctions. Events come from sites close to the footpoints of jets seen in Atmospheric Imaging Assembly (AIA) images, and possibly from the landing site of high-velocity flows. They are not caused by rapid rotation in spicules. Title: European Solar Physics: moving from SOHO to Solar Orbiter and beyond Authors: Solanki, S. K.; Teriaca, L.; Barthol, P.; Curdt, W.; Inhester, B. Bibcode: 2013MmSAI..84..286S Altcode: When ESA and NASA launched the Solar and Heliospheric Observatory (SOHO) to the Sun-Earth L1 point, they also launched European solar physics into a steep upward trajectory. Thanks to the battery of instruments on SOHO our picture of the Sun changed dramatically from that of a sedate, nearly static star into that of a highly structured, dynamic one. Subsequent solar missions have probed higher energy radiation, gazed at the Sun from new vantage points in the ecliptic, analysed the Sun at higher spatial resolution and imaged the whole Sun in many wavelengths at high cadence. Nonetheless, SOHO is still going strong and still delivering unique data. In the meantime European solar physicists are working hard on the next major mission, Solar Orbiter, now being implemented as the M1 mission of ESA's Cosmic Vision program. Solar Orbiter will leave the Earth's orbit and move ever closer to the Sun, reaching a perihelion inside the orbit of Mercury. This will allow it to sample the Sun's dynamic inner heliosphere in situ, while probing the source regions of the ambient solar wind with its remote sensing instruments, a unique combination. Solar Orbiter will also leave the ecliptic and, for the first time, image the Sun's poles. This will bring us closer to finding the missing pieces of the puzzle on how the solar dynamo works. Beyond Solar Orbiter are further exciting prospects, such as the Solar-C mission, or the large European Solar Telescope. Here an overview of solar missions and telescopes and the associated science is given from a European perspective. Title: Doppler shift of hot coronal lines in a moss area of an active region Authors: Dadashi, N.; Teriaca, L.; Tripathi, D.; Solanki, S. K.; Wiegelmann, T. Bibcode: 2012A&A...548A.115D Altcode: 2012arXiv1211.5473D The moss is the area at the footpoint of the hot (3 to 5 MK) loops forming the core of the active region where emission is believed to result from the heat flux conducted down to the transition region from the hot loops. Studying the variation of Doppler shift as a function of line formation temperatures over the moss area can give clues on the heating mechanism in the hot loops in the core of the active regions. We investigate the absolute Doppler shift of lines formed at temperatures between 1 MK and 2 MK in a moss area within active region NOAA 11243 using a novel technique that allows determining the absolute Doppler shift of EUV lines by combining observations from the SUMER and EIS spectrometers. The inner (brighter and denser) part of the moss area shows roughly constant blue shift (upward motions) of 5 km s-1 in the temperature range of 1 MK to 1.6 MK. For hotter lines the blue shift decreases and reaches 1 km s-1 for Fe xv 284 Å (~2 MK). The measurements are discussed in relation to models of the heating of hot loops. The results for the hot coronal lines seem to support the quasi-steady heating models for nonsymmetric hot loops in the core of active regions. Title: LEMUR: Large European module for solar Ultraviolet Research. European contribution to JAXA's Solar-C mission Authors: Teriaca, Luca; Andretta, Vincenzo; Auchère, Frédéric; Brown, Charles M.; Buchlin, Eric; Cauzzi, Gianna; Culhane, J. Len; Curdt, Werner; Davila, Joseph M.; Del Zanna, Giulio; Doschek, George A.; Fineschi, Silvano; Fludra, Andrzej; Gallagher, Peter T.; Green, Lucie; Harra, Louise K.; Imada, Shinsuke; Innes, Davina; Kliem, Bernhard; Korendyke, Clarence; Mariska, John T.; Martínez-Pillet, Valentin; Parenti, Susanna; Patsourakos, Spiros; Peter, Hardi; Poletto, Luca; Rutten, Robert J.; Schühle, Udo; Siemer, Martin; Shimizu, Toshifumi; Socas-Navarro, Hector; Solanki, Sami K.; Spadaro, Daniele; Trujillo-Bueno, Javier; Tsuneta, Saku; Dominguez, Santiago Vargas; Vial, Jean-Claude; Walsh, Robert; Warren, Harry P.; Wiegelmann, Thomas; Winter, Berend; Young, Peter Bibcode: 2012ExA....34..273T Altcode: 2011ExA...tmp..135T; 2011arXiv1109.4301T The solar outer atmosphere is an extremely dynamic environment characterized by the continuous interplay between the plasma and the magnetic field that generates and permeates it. Such interactions play a fundamental role in hugely diverse astrophysical systems, but occur at scales that cannot be studied outside the solar system. Understanding this complex system requires concerted, simultaneous solar observations from the visible to the vacuum ultraviolet (VUV) and soft X-rays, at high spatial resolution (between 0.1'' and 0.3''), at high temporal resolution (on the order of 10 s, i.e., the time scale of chromospheric dynamics), with a wide temperature coverage (0.01 MK to 20 MK, from the chromosphere to the flaring corona), and the capability of measuring magnetic fields through spectropolarimetry at visible and near-infrared wavelengths. Simultaneous spectroscopic measurements sampling the entire temperature range are particularly important. These requirements are fulfilled by the Japanese Solar-C mission (Plan B), composed of a spacecraft in a geosynchronous orbit with a payload providing a significant improvement of imaging and spectropolarimetric capabilities in the UV, visible, and near-infrared with respect to what is available today and foreseen in the near future. The Large European Module for solar Ultraviolet Research (LEMUR), described in this paper, is a large VUV telescope feeding a scientific payload of high-resolution imaging spectrographs and cameras. LEMUR consists of two major components: a VUV solar telescope with a 30 cm diameter mirror and a focal length of 3.6 m, and a focal-plane package composed of VUV spectrometers covering six carefully chosen wavelength ranges between 170 Å and 1270 Å. The LEMUR slit covers 280'' on the Sun with 0.14'' per pixel sampling. In addition, LEMUR is capable of measuring mass flows velocities (line shifts) down to 2 km s - 1 or better. LEMUR has been proposed to ESA as the European contribution to the Solar C mission. Title: Spectroscopic observations of propagating disturbances in a polar coronal hole: evidence of slow magneto-acoustic waves Authors: Gupta, G. R.; Teriaca, L.; Marsch, E.; Solanki, S. K.; Banerjee, D. Bibcode: 2012A&A...546A..93G Altcode: 2012arXiv1209.3524G
Aims: We focus on detecting and studying quasi-periodic propagating features that have been interpreted in terms of both slow magneto-acoustic waves and of high-speed upflows.
Methods: We analyzed long-duration spectroscopic observations of the on-disk part of the south polar coronal hole taken on 1997 February 25 by the SUMER spectrometer onboard SOHO. We calibrated the velocity with respect to the off-limb region and obtained time-distance maps in intensity, Doppler velocity, and line width. We also performed a cross-correlation analysis on different time series curves at different latitudes. We studied average spectral line profiles at the roots of propagating disturbances and along the propagating ridges, and performed a red-blue asymmetry analysis.
Results: We clearly find propagating disturbances in intensity and Doppler velocity with a projected propagation speed of about 60 ± 4.8 km s-1 and a periodicity of ≈14.5 min. To our knowledge, this is the first simultaneous detection of propagating disturbances in intensity as well as in Doppler velocity in a coronal hole. During the propagation, an intensity enhancement is associated with a blueshifted Doppler velocity. These disturbances are clearly seen in intensity also at higher latitudes (i.e., closer to the limb), while disturbances in Doppler velocity become faint there. The spectral line profiles averaged along the propagating ridges are found to be symmetric, to be well fitted by a single Gaussian, and have no noticeable red-blue asymmetry.
Conclusions: Based on our analysis, we interpret these disturbances in terms of propagating slow magneto-acoustic waves. 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: A prototype of the UV detector for METIS on Solar Orbiter Authors: Uslenghi, M.; Incorvaia, S.; Fiorini, M.; Schühle, U. H.; Teriaca, L.; Wilkinson, E.; Siegmund, O. H.; Antonucci, E.; Fineschi, S.; Naletto, G.; Nicolini, G.; Nicolosi, G.; Romoli, M.; Focardi, M. Bibcode: 2012SPIE.8443E..3IU Altcode: METIS (Multi Element Telescope for Imaging and Spectroscopy) is one of the instruments included in the science payload of the ESA mission Solar Orbiter: a coronograph able to perform broadband polarization imaging in the visible range, and narrow band imaging in UV (HI Lyman-α) and EUV (HeII Lyman-α). In addition, it will acquire spectra of the solar corona simultaneously to UV/EUV imaging. It will be equipped with two detectors: a hybrid APS dedicated to the visible channel and an Intensified APS for the UV/EUV channel. The spectroscopic channel will share the same detector as the UV/EUV corona imaging, with the spectrum imaged on a portion of the detector not used by the corona image. We present the development of the UV/EUV detector consisting of a CMOS APS imaging device to be coupled with a microchannel plate intensifier. Other than constraints related to the harsh environment (radiation, temperature, visible stray-light), the METIS UV detector has the additional challenge of managing different count rates associated with the three different kind of measurements (UV imaging, EUV imaging and spectroscopy). The required dynamic range is further extended since observations will be planned at different distances from the Sun, varying image scale over a fixed vignetting function. We will present the architecture of this UV detector, describing the prototype developed in order to optimize the performance on the overall dynamic range required by METIS. 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: Spectroscopic Observations of Fe XVIII in Solar Active Regions Authors: Teriaca, Luca; Warren, Harry P.; Curdt, Werner Bibcode: 2012ApJ...754L..40T Altcode: 2012arXiv1206.4228T The large uncertainties associated with measuring the amount of high temperature emission in solar active regions (ARs) represents a significant impediment to making progress on the coronal heating problem. Most current observations at temperatures of 3 MK and above are taken with broadband soft X-ray instruments. Such measurements have proven difficult to interpret unambiguously. Here, we present the first spectroscopic observations of the Fe XVIII 974.86 Å emission line in an on-disk AR taken with the SUMER instrument on SOHO. Fe XVIII has a peak formation temperature of 7.1 MK and provides important constraints on the amount of impulsive heating in the corona. Detailed evaluation of the spectra and comparison of the SUMER data with soft X-ray images from the X-Ray Telescope on Hinode confirm that this line is unblended. We also compare the spectroscopic data with observations from the Atmospheric Imaging Assembly (AIA) 94 Å channel on the Solar Dynamics Observatory. The AIA 94 Å channel also contains Fe XVIII, but is blended with emission formed at lower temperatures. We find that it is possible to remove the contaminating blends and form relatively pure Fe XVIII images that are consistent with the spectroscopic observations from SUMER. The observed spectra also contain the Ca XIV 943.63 Å line that, although a factor 2-6 weaker than the Fe XVIII 974.86 Å line, allows us to probe the plasma around 3.5 MK. The observed ratio between the two lines indicates (isothermal approximation) that most of the plasma in the brighter Fe XVIII AR loops is at temperatures between 3.5 and 4 MK. Title: Multi wavelength Study of Polar X-ray Jets using Hinode and SDO Authors: Chandrashekhar, K.; Gupta, Girjesh R.; Banerjee, Dipankar; Teriaca, Luca Bibcode: 2012cosp...39..310C Altcode: 2012cosp.meet..310C High spatial and temporal resolution images of the solar transition region in quiet and coronal hole regions show a dynamical environment where mass flows and jets are commonly observed. We study a polar jet with a combination of imaging from EIS and XRT on board Hinode. We measure jet parameters, e.g. length, width, life time, outward speed. The bright point associated with the jet is part of a sigmoidal structure. The time of appearance of the sigmoid and ejection of plasma from the bright point suggests that the sigmoid is a progenitor of the jet. Before and after the main jet event, we observe small collimated plasma flows from the bright point to the footpoint of the jet. These observations suggest that repetitive reconnection between emerging flux and the ambient open field in the coronal hole causes the polar jets. Average outward speed of the jet is 160 km/s, well below the escape speed. The enhancement in the light curves of low temperature EIS lines after the occurrence of the jet suggests that the jet material is falling back. To supplement these results we studied two polar coronal jets observed by AIA and HMI on board SDO. These jets have speeds around 200 to 300 km/s. The temperature response and the associated magnetic flux changes are studied using the multiple channels of AIA and HMI. The light curves as recorded with different AIA channels are compared with magnetic flux evolution as recorded by HMI. We will show that in spite of the better time and spatial resolution of AIA, the overlapping temperature response of AIA channels causes difficulty in proper diagnosis. Title: Spectroscopic Observations of Propagating Disturbances in Polar Coronal Hole Authors: Gupta, Girjesh R.; Marsch, Eckart; Solanki, Sami K.; Banerjee, Dipankar; Teriaca, Luca Bibcode: 2012cosp...39..689G Altcode: 2012cosp.meet..689G We focus on long duration spectroscopic observations of the south polar coronal hole taken on 1997 February 25 by the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) spectrometer aboard SOHO. We analyze the data in the on-disk part of the coronal hole to find any signature of propagating waves or high speed up-flows. We find the clear presence of propagating disturbances in intensity and Doppler velocity with a projected propagation speed of about 60~km~s^{-1} and a periodicity of ≈14.5~min. During the propagation, the intensity enhancement is associated with a blue-shifted Doppler velocity. These disturbances are clearly seen in intensity at higher latitudes (i.e. closer to the limb), whereas disturbances in Doppler velocity becomes faint there. We study average spectral line profiles at the roots of these disturbances and along the propagating ridge. Based on our analysis, we interpret these disturbances in terms of propagating slow magneto-acoustic waves. Title: Explosive events - swirling transition region jets Authors: Curdt, Werner; Kamio, Suguru; Tian, Hui; Teriaca, Luca Bibcode: 2012cosp...39..381C Altcode: 2012cosp.meet..381C The bi-directed, fast Doppler motion of explosive events observed spectroscopically in the transition region emission is classically interpreted as a pair of jets moving upward and downward from a reconnection site. We discuss the problems of such a model and provide evidence for an alternative scenario to explain the nature of so-called 'explosive events'. The discrepancy of fast Doppler motion without detectable motion in the image plane is an old, unsolved problem. We now provide the spectral tilt and the jet bifurcation as additional arguments. Both features are indicative of rotational motion in narrow structures. We interpret the bifurcation as the result of rotation of hollow cylindrical structures and demonstrate that such a sheath model can also be applied to explain the nature of the puzzling 'explosive events'. We find that the spectral tilt, the lack of apparent motion, the bifurcation, and a rapidly growing number of direct observations support an alternative scenario of linear, spicular-sized jets with a strong spinning motion. Title: Solar magnetism eXplorer (SolmeX). Exploring the magnetic field in the upper atmosphere of our closest star Authors: Peter, Hardi; Abbo, L.; Andretta, V.; Auchère, F.; Bemporad, A.; Berrilli, F.; Bommier, V.; Braukhane, A.; Casini, R.; Curdt, W.; Davila, J.; Dittus, H.; Fineschi, S.; Fludra, A.; Gandorfer, A.; Griffin, D.; Inhester, B.; Lagg, A.; Landi Degl'Innocenti, E.; Maiwald, V.; Sainz, R. Manso; Martínez Pillet, V; Matthews, S.; Moses, D.; Parenti, S.; Pietarila, A.; Quantius, D.; Raouafi, N. -E.; Raymond, J.; Rochus, P.; Romberg, O.; Schlotterer, M.; Schühle, U.; Solanki, S.; Spadaro, D.; Teriaca, L.; Tomczyk, S.; Trujillo Bueno, J.; Vial, J. -C. Bibcode: 2012ExA....33..271P Altcode: 2011arXiv1108.5304P; 2011ExA...tmp..134P The magnetic field plays a pivotal role in many fields of Astrophysics. This is especially true for the physics of the solar atmosphere. Measuring the magnetic field in the upper solar atmosphere is crucial to understand the nature of the underlying physical processes that drive the violent dynamics of the solar corona—that can also affect life on Earth. SolmeX, a fully equipped solar space observatory for remote-sensing observations, will provide the first comprehensive measurements of the strength and direction of the magnetic field in the upper solar atmosphere. The mission consists of two spacecraft, one carrying the instruments, and another one in formation flight at a distance of about 200 m carrying the occulter to provide an artificial total solar eclipse. This will ensure high-quality coronagraphic observations above the solar limb. SolmeX integrates two spectro-polarimetric coronagraphs for off-limb observations, one in the EUV and one in the IR, and three instruments for observations on the disk. The latter comprises one imaging polarimeter in the EUV for coronal studies, a spectro-polarimeter in the EUV to investigate the low corona, and an imaging spectro-polarimeter in the UV for chromospheric studies. SOHO and other existing missions have investigated the emission of the upper atmosphere in detail (not considering polarization), and as this will be the case also for missions planned for the near future. Therefore it is timely that SolmeX provides the final piece of the observational quest by measuring the magnetic field in the upper atmosphere through polarimetric observations. Title: The quiet Sun average Doppler shift of coronal lines up to 2 MK Authors: Dadashi, N.; Teriaca, L.; Solanki, S. K. Bibcode: 2011A&A...534A..90D Altcode: 2011arXiv1109.4493D Context. The average Doppler shift shown by spectral lines formed from the chromosphere to the corona reveals important information on the mass and energy balance of the solar atmosphere, providing an important observational constraint to any models of the solar corona. Previous spectroscopic observations of vacuum ultra-violet (VUV) lines have revealed a persistent average wavelength shift of lines formed at temperatures up to 1 MK. At higher temperatures, the behaviour is still essentially unknown.
Aims: Here we analyse combined SUMER (Solar Ultraviolet Measurements of Emitted Radiation)/SoHO (Solar and Heliospheric Observatory) and EIS (EUV Imaging Spectrometer)/Hinode observations of the quiet Sun around disk centre to determine, for the first time, the average Doppler shift of several spectral lines formed between 1 and 2 MK, where the largest part of the quiet coronal emission is formed.
Methods: The measurements are based on a novel technique applied to EIS spectra to measure the difference in Doppler shift between lines formed at different temperatures. Simultaneous wavelength-calibrated SUMER spectra allow establishing the absolute value at the reference temperature of T ≈ 1 MK.
Results: The average line shifts at 1 MK < T < 1.8 MK are modestly, but clearly bluer than those observed at 1 MK. By accepting an average blue shift of about (-1.8 ± 0.6) km s-1 at 1 MK (as provided by SUMER measurements), this translates into a maximum Doppler shift of (-4.4 ± 2.2) km s-1 around 1.8 MK. The measured value appears to decrease to about (-1.3 ± 2.6) km s-1 at the Fe xv formation temperature of 2.1 MK.
Conclusions: The measured average Doppler shift between 0.01 and 2.1 MK, for which we provide a parametrisation, appears to be qualitatively and roughly quantitatively consistent with what foreseen by 3D coronal models where heating is produced by dissipation of currents induced by photospheric motions and by reconnection with emerging magnetic flux. Title: LEMUR (Large European Module for solar Ultraviolet Research): a VUV imaging spectrograph for the JAXA Solar-C Mission Authors: Korendyke, Clarence M.; Teriaca, Luca; Doschek, George A.; Harra, Louise K.; Schühle, Udo H.; Shimizu, Toshifumi Bibcode: 2011SPIE.8148E..0IK Altcode: 2011SPIE.8148E..17K LEMUR is a VUV imaging spectrograph with 0.28" resolution. Incident solar radiation is imaged onto the spectrograph slit by a single mirror telescope consisting of a 30-cm steerable f/12 off-axis paraboloid mirror. The spectrograph slit is imaged and dispersed by a highly corrected grating that focuses the solar spectrum over the detectors. The mirror is coated with a suitable multilayer with B4C top-coating providing a reflectance peak around 18.5 nm besides the usual B4C range above 500Å. The grating is formed by two halves, one optimized for performances around 185Å and the other above 500Å. Three intensified CCD cameras will record spectra above 50 nm while a large format CCD array with an aluminum filter will be used around 185Å. Title: The Lyman-alpha telescope of the extreme ultraviolet imager on Solar Orbiter Authors: Schühle, Udo; Halain, Jean-Philippe; Meining, Stefan; Teriaca, Luca Bibcode: 2011SPIE.8148E..0KS Altcode: 2011SPIE.8148E..19S On the Solar Orbiter mission, the Extreme Ultraviolet Imager (EUI) set of filtergraph-telescopes consists of two highresolution imagers (HRI) and one dual-band full Sun imager (FSI) that will provide images of the solar atmosphere in the extreme ultraviolet and in the Lyman-α line of hydrogen at 121.6 nm. The Lyman-α HRI, in particular, will provide imaging of the upper chromospheres/lower transition region of the Sun at unprecedented high cadence and at an angular resolution of 1" (corresponding to a spatial resolution of 200 km at perihelion). For vacuum-ultraviolet imaging of the Sun the main requirements for the instrumentation are high resolution, high cadence, and large dynamic range. We present here the novel solutions of the instrument design and show in detail the predicted performance of this telescope. We describe in detail how the high throughput and spectral purity at 121.6 nm is achieved. The technical solutions include multilayer coatings of the telescope mirrors for high reflectance at 121.6 nm, combined with interference filters and a multichannel-plate intensified CMOS active pixel camera. We make use of the design flexibilities of this camera to optimize the dynamic range in the focal plane. Title: Hydrogen Lyα and Lyβ Radiances and Profiles in Polar Colornal Holes Authors: Tian, Hui; Teriaca, Luca; Curdt, Werner; Vial, Jean-Claude Bibcode: 2011shin.confE.166T Altcode: The hydrogen Lyα plays a dominant role in the radiative energy transport in the lower transition region, and is important for the studies of transition-region structure as well as solar wind origin. We investigate the Lyα profiles obtained by the Solar Ultraviolet Measurement of Emitted Radiation spectrograph on the Solar and Heliospheric Observatory spacecraft in coronal holes and the quiet Sun. In a subset of these observations, the Hi Lyβ, Si III, and Ovi lines were also (quasi-)simultaneously recorded. We find that the distances between the two peaks of Lyα profiles are larger in coronal holes than in the quiet Sun, indicating a larger opacity in coronal holes. This difference might result from the different magnetic structures or the different radiation fields in the two regions. Most of the Lyβ profiles in the coronal hole have a stronger blue peak, in contrast to those in quiet-Sun regions while in both regions the Lyα profiles are stronger in the blue peak. Although the asymmetries are likely to be produced by differential flows in the solar atmosphere, their detailed formation processes are still unclear. The radiance ratio between Lyα and Lyβ decreases toward the limb in the coronal hole, which might be due to the different opacity of the two lines. We also find that the radiance distributions of the four lines are set by a combined effect of limb brightening and the different emission level between coronal holes and the quiet Sun. Title: Propagating MHD Waves in Coronal Holes Authors: Banerjee, D.; Gupta, G. R.; Teriaca, L. Bibcode: 2011SSRv..158..267B Altcode: 2010SSRv..tmp..180B; 2010arXiv1009.2980B Coronal holes are the coolest and darkest regions of the upper solar atmosphere, as observed both on the solar disk and above the solar limb. Coronal holes are associated with rapidly expanding open magnetic fields and the acceleration of the high-speed solar wind. During the years of the solar minima, coronal holes are generally confined to the Sun's polar regions, while at solar maxima they can also be found at lower latitudes. Waves, observed via remote sensing and detected in-situ in the wind streams, are most likely responsible for the wind and several theoretical models describe the role of MHD waves in the acceleration of the fast solar wind. This paper reviews the observational evidences of detection of propagating waves in these regions. The characteristics of the waves, like periodicities, amplitude, speed provide input parameters and also act as constraints on theoretical models of coronal heating and solar wind acceleration. Title: Morphology, dynamics and plasma parameters of plumes and inter-plume regions in solar coronal holes Authors: Wilhelm, K.; Abbo, L.; Auchère, F.; Barbey, N.; Feng, L.; Gabriel, A. H.; Giordano, S.; Imada, S.; Llebaria, A.; Matthaeus, W. H.; Poletto, G.; Raouafi, N. -E.; Suess, S. T.; Teriaca, L.; Wang, Y. -M. Bibcode: 2011A&ARv..19...35W Altcode: 2011arXiv1103.4481W Coronal plumes, which extend from solar coronal holes (CH) into the high corona and—possibly—into the solar wind (SW), can now continuously be studied with modern telescopes and spectrometers on spacecraft, in addition to investigations from the ground, in particular, during total eclipses. Despite the large amount of data available on these prominent features and related phenomena, many questions remained unanswered as to their generation and relative contributions to the high-speed streams emanating from CHs. An understanding of the processes of plume formation and evolution requires a better knowledge of the physical conditions at the base of CHs, in plumes and in the surrounding inter-plume regions. More specifically, information is needed on the magnetic field configuration, the electron densities and temperatures, effective ion temperatures, non-thermal motions, plume cross sections relative to the size of a CH, the plasma bulk speeds, as well as any plume signatures in the SW. In spring 2007, the authors proposed a study on `Structure and dynamics of coronal plumes and inter-plume regions in solar coronal holes' to the International Space Science Institute (ISSI) in Bern to clarify some of these aspects by considering relevant observations and the extensive literature. This review summarizes the results and conclusions of the study. Stereoscopic observations allowed us to include three-dimensional reconstructions of plumes. Multi-instrument investigations carried out during several campaigns led to progress in some areas, such as plasma densities, temperatures, plume structure and the relation to other solar phenomena, but not all questions could be answered concerning the details of plume generation process(es) and interaction with the SW. Title: Evolution of microflares associated with bright points in coronal holes and in quiet regions Authors: Kamio, S.; Curdt, W.; Teriaca, L.; Innes, D. E. Bibcode: 2011A&A...529A..21K Altcode: 2010arXiv1009.1957K
Aims: We aim to find similarities and differences between microflares at coronal bright points found in quiet regions and coronal holes, and to study their relationship with large scale flares.
Methods: Coronal bright points in quiet regions and in coronal holes were observed with Hinode/EIS using the same sequence. Microflares associated with bright points are identified from the X-ray lightcurve. The temporal variation of physical properties was traced in the course of microflares.
Results: The lightcurves of microflares indicated an impulsive peak at hot emission followed by an enhancement at cool emission, which is compatible with the cooling model of flare loops. The density was found to increase at the rise of the impulsive peak, supporting chromospheric evaporation models. A notable difference is found in the surroundings of microflares; diffuse coronal jets are produced above microflares in coronal holes while coronal dimmings are formed in quiet regions.
Conclusions: The microflares associated with bright points share common characteristics to active region flares. The difference in the surroundings of microflares are caused by open and closed configurations of the pre-existing magnetic field. Title: Accelerating Waves in Polar Coronal Holes as Seen by EIS and SUMER Authors: Gupta, G. R.; Banerjee, D.; Teriaca, L.; Imada, S.; Solanki, S. Bibcode: 2010ApJ...718...11G Altcode: 2010arXiv1005.3453G We present EIS/Hinode and SUMER/SOHO observations of propagating disturbances detected in coronal lines in inter-plume and plume regions of a polar coronal hole. The observation was carried out on 2007 November 13 as part of the JOP196/HOP045 program. The SUMER spectroscopic observation gives information about fluctuations in radiance and on both resolved (Doppler shift) and unresolved (Doppler width) line-of-sight velocities, whereas EIS 40'' wide slot images detect fluctuations only in radiance but maximize the probability of overlapping field of view between the two instruments. From distance-time radiance maps, we detect the presence of propagating waves in a polar inter-plume region with a period of 15-20 minutes and a propagation speed increasing from 130 ± 14 km s-1 just above the limb to 330 ± 140 km s-1 around 160'' above the limb. These waves can be traced to originate from a bright region of the on-disk part of the coronal hole where the propagation speed is in the range of 25 ± 1.3 to 38 ± 4.5 km s-1, with the same periodicity. These on-disk bright regions can be visualized as the base of the coronal funnels. The adjacent plume region also shows the presence of propagating disturbances with the same range of periodicity but with propagation speeds in the range of 135 ± 18 to 165 ± 43 km s-1 only. A comparison between the distance-time radiance map of the two regions indicates that the waves within the plumes are not observable (may be getting dissipated) far off-limb, whereas this is not the case in the inter-plume region. A correlation analysis was also performed to find out the time delay between the oscillations at several heights in the off-limb region, finding results consistent with those from the analysis of the distance-time maps. To our knowledge, this result provides first spectroscopic evidence of the acceleration of propagating disturbances in the polar region close to the Sun (within 1.2 R/R sun), which provides clues to the understanding of the origin of these waves. We suggest that the waves are likely either Alfvénic or fast magnetoacoustic in the inter-plume region and slow magnetoacoustic in the plume region. This may lead to the conclusion that inter-plumes are a preferred channel for the acceleration of the fast solar wind. Title: Observations of a rotating macrospicule associated with an X-ray jet Authors: Kamio, S.; Curdt, W.; Teriaca, L.; Inhester, B.; Solanki, S. K. Bibcode: 2010A&A...510L...1K Altcode: 2010arXiv1001.1924K
Aims: We attempt to understand the driving mechanism of a macrospicule and its relationship with a coronal jet.
Methods: We study the dynamics of a macrospicule and an associated coronal jet captured by multi-spacecraft observations. Doppler velocities in both the macrospicule and the coronal jet are determined by EIS and SUMER spectra. Their temporal evolution is studied using X-ray and He II λ304 images.
Results: A blueshift of -120 ± 15 km s-1 is detected on one side of the macrospicule, while a redshift of 50 ± 6 km s-1 is found at the base of the other side. The inclination angle of the macrospicule inferred from a stereoscopic analysis with STEREO suggests that the measured Doppler velocities can be attributed to a rotating motion of the macrospicule rather than a radial flow or an expansion.
Conclusions: The macrospicule is driven by the unfolding motion of a twisted magnetic flux rope, while the associated X-ray jet is a radial outflow. Title: The SUMER Ly-α line profile in quiescent prominences Authors: Curdt, W.; Tian, H.; Teriaca, L.; Schühle, U. Bibcode: 2010A&A...511L...4C Altcode: 2010arXiv1002.1197C
Aims: As the result of a novel observing technique, we publish for the first time SoHO-SUMER observations of the true spectral line profile of hydrogen Lyman-α in quiescent prominences. Because SoHO is not in Earth orbit, our high-quality data set is free of geocoronal absorption. We studied the line profile to complement earlier observations of the higher Lyman lines and to substantiate recent model predictions.
Methods: We applied the reduced-aperture observing mode to two prominence targets and did a statistical analysis of the line profiles in both data sets. In particular, we investigated the shape of the profile, the radiance distribution, and the line shape-to-radiance interrelation. We also compared Ly-α data to co-temporal λ 1206 Si iii data.
Results: We find that the average profile of Ly-α has a blue-peak dominance and is reversed more if the line-of-sight is perpendicular to the field lines. The contrast of Ly-α prominence emission rasters is very low, and the radiance distribution differs from the log-normal distribution of the disk. Features in the Si iii line are not always co-spatial with Ly-α emission.
Conclusions: Our empirical results support recent multi-thread models, which predict that asymmetries and depths of the self-reversal depend on the orientation of the prominence axis relative to the line-of-sight. Title: The Structure and Dynamics of the Upper Chromosphere and Lower Transition Region as Revealed by the Subarcsecond VAULT Observations Authors: Vourlidas, A.; Sanchez Andrade-Nuño, B.; Landi, E.; Patsourakos, S.; Teriaca, L.; Schühle, U.; Korendyke, C. M.; Nestoras, I. Bibcode: 2010SoPh..261...53V Altcode: 2009arXiv0912.2272V The Very high Angular resolution ULtraviolet Telescope (VAULT) is a sounding rocket payload built to study the crucial interface between the solar chromosphere and the corona by observing the strongest line in the solar spectrum, the Ly α line at 1216 Å. In two flights, VAULT succeeded in obtaining the first ever subarcsecond ( 0.5\hbox{$^''$} ) images of this region with high sensitivity and cadence. Detailed analyses of those observations contributed significantly to new ideas about the nature of the transition region. Here, we present a broad overview of the Ly α atmosphere as revealed by the VAULT observations and bring together past results and new analyses from the second VAULT flight to create a synthesis of our current knowledge of the high-resolution Ly α Sun. We hope that this work will serve as a good reference for the design of upcoming Ly α telescopes and observing plans. Title: Accelerating disturbances in polar plume and inter-plume Authors: Gupta, Girjesh R.; Banerjee, Dipankar; Teriaca, Luca; Imada, Shinsuke; Solanki, Sami Bibcode: 2010cosp...38.2937G Altcode: 2010cosp.meet.2937G We present EIS/Hinode & SUMER/SoHO joint observations allowing the first spectroscopic detection of accelerating disturbances as recorded with coronal lines in inter-plume and plume regions of a polar coronal hole. From time-distance radiance maps, we detect the presence of propagating disturbances in a polar inter-plume region with a period of 15 to 20 min and a propagation speed increasing from 130±14 km/s just above the limb, to 330±140 km/s around 160" above the limb. These disturbances can also be traced to originate from a bright region of the on-disk part of the coronal hole where the propagation speed was found to be in the range of 25±1.3 to 38±4.5 km/s, with the same periodicity. These on-disk bright regions can be vi-sualized as the base of the coronal funnels. The adjacent plume region also shows the presence of propagating disturbance with the same range of period but with propagation speeds in the range of 135±18 to 165±43 km/s only. A comparison between the time-distance radiance map of both regions, indicate that the disturbances within the plumes are not observable (may be getting dissipated) far off-limb whereas this is not the case in the inter-plume region. Conclu-sions drawn from these observations in terms of accelerating waves or high speed jets/upflows will be discussed. Title: Impusive heating of bright points observed by EIS and SUMER Authors: Kamio, Suguru; Curdt, Werner; Teriaca, Luca; Innes, Davina Bibcode: 2010cosp...38.2838K Altcode: 2010cosp.meet.2838K We studied the temporal variation of bright points (BPs) in the quiet region and in the coronal hole. Time series of X-ray images show significant emission increases in BPs with durations shorter than 10 min. Since these impulsive brightenings are frequently found all over the Sun, study of their mechanism is important for understanding the dynamics in the quiescent corona. Characteristics of light curves of BPs in the transition region and in the corona are similar to those of solar flares, though at a much smaller scale. Fast raster scans with SOHO/SUMER and Hinode/EIS allowed us to obtain light curves in multiple emission lines. At the peak of X-ray flux, a significant emission in Fe XV (2MK), which is normally very weak in BPs, is detected. In addition, diagnostic using the Fe XII line pair indicate density increase in BPs. These results suggest that impulsive heating takes place in the corona, which causes chromospheric evaporation supplying hot plasma into coronal loops. After the X-ray peak, delayed emission increase in He II and O IV is observed, which is interpreted as the cooling of hot plasma. We will discuss the relationship between these small scale flares and jets. Title: Results from the Past Hinode/SUMER Campaigns Authors: Teriaca, L. Bibcode: 2009ASPC..415..309T Altcode: The SUMER VUV spectrometer aboard SOHO currently observes spectral lines and continua in the 67 nm to 150 nm range. This emission mostly samples the solar atmosphere from the chromosphere to the lower corona (≤ 1 MK), through the transition region. As such, this instrument is an ideal complement to the Hinode instruments, helping coupling the observations of the photospheric magnetic field and of the photospheric and chromospheric emission performed by SOT with the images and spectra of the hot corona (≥ 1 MK) obtained by XRT and EIS. Since the launch of Hinode in the fall of 2006, there have been six SUMER campaigns during which combined observations were obtained. Of these, three are full bilateral joint campaigns, the last of which was run at the end of September 2008. Here I report on some of the scientific results derived from these campaigns. Title: Multi-Instrument Campaigns to Observe the Off-Limb Corona Authors: Del Zanna, G.; Andretta, V.; Poletto, G.; Teriaca, L.; Ko, Y. -K.; Mason, H. E.; Vourdilas, A.; Bemporad, A.; Magri, M. Bibcode: 2009ASPC..415..315D Altcode: We briefly describe two multi-instrument campaigns we coordinated to observe the off-limb corona in 2007, with some preliminary results. The first one (Hinode HOP 7) was a SOHO/Hinode/TRACE/STEREO/Ulysses week-long campaign during the SOHO-Ulysses quadrature in 2007 May. We could not achieve all of our goals, however we were very fortunate in that the ``Del Zanna'' active region appeared on the Sun at the right longitude, and that a filament eruption and a CME were observed. Of particular significance is the finding of large (100 km s-1) non-thermal broadenings in all coronal lines observed by Hinode/EIS in the region where the filament was erupting. The second campaign (Hinode HOP 44) involved SOHO (CDS, SUMER, UVCS), Hinode, and TRACE to measure the physical parameters of plume/interplume regions in the polar coronal holes from the low corona to 1.7 solar radii, on 30/10-4/11. We obtained a good set of observations, however various instrumental constraints and the lack of fully developed plumes limited our goals. Title: Hydrogen Lyα and Lyβ Radiances and Profiles in Polar Coronal Holes Authors: Tian, Hui; Teriaca, Luca; Curdt, Werner; Vial, Jean-Claude Bibcode: 2009ApJ...703L.152T Altcode: 2009arXiv0909.0735T The hydrogen Lyα plays a dominant role in the radiative energy transport in the lower transition region, and is important for the studies of transition-region structure as well as solar wind origin. We investigate the Lyα profiles obtained by the Solar Ultraviolet Measurement of Emitted Radiation spectrograph on the Solar and Heliospheric Observatory spacecraft in coronal holes and the quiet Sun. In a subset of these observations, the H I Lyβ, Si III, and O VI lines were also (quasi-)simultaneously recorded. We find that the distances between the two peaks of Lyα profiles are larger in coronal holes than in the quiet Sun, indicating a larger opacity in coronal holes. This difference might result from the different magnetic structures or the different radiation fields in the two regions. Most of the Lyβ profiles in the coronal hole have a stronger blue peak, in contrast to those in quiet-Sun regions while in both regions the Lyα profiles are stronger in the blue peak. Although the asymmetries are likely to be produced by differential flows in the solar atmosphere, their detailed formation processes are still unclear. The radiance ratio between Lyα and Lyβ decreases toward the limb in the coronal hole, which might be due to the different opacity of the two lines. We also find that the radiance distributions of the four lines are set by a combined effect of limb brightening and the different emission level between coronal holes and the quiet Sun. Title: Solar transition region above sunspots Authors: Tian, H.; Curdt, W.; Teriaca, L.; Landi, E.; Marsch, E. Bibcode: 2009A&A...505..307T Altcode: 2009arXiv0906.2211T Aims: We study the transition region (TR) properties above sunspots and the surrounding plage regions, by analyzing several sunspot reference spectra obtained by the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) instrument in March 1999 and November 2006.
Methods: We compare the SUMER spectra observed in the umbra, penumbra, plage, and sunspot plume regions. The hydrogen Lyman line profiles averaged in each of the four regions are presented. For the sunspot observed in 2006, the electron densities, differential emission measure (DEM), and filling factors of the TR plasma in the four regions are also investigated.
Results: The self-reversals of the hydrogen Lyman line profiles are almost absent in sunspots at different locations (at heliocentric angles of up to 49°) on the solar disk. In the sunspot plume, the Lyman lines are also not reversed, whilst the lower Lyman line profiles observed in the plage region are obviously reversed, a phenomenon found also in the normal quiet Sun. The TR densities of the umbra and plume are similar and one order of magnitude lower than those of the plage and penumbra. The DEM curve of the sunspot plume exhibits a peak centered at log(T / K) ~ 5.45, which exceeds the DEM of other regions by one to two orders of magnitude at these temperatures. We also find that more than 100 lines, which are very weak or not observed anywhere else on the Sun, are well observed by SUMER in the sunspot, especially in the sunspot plume.
Conclusions: We suggest that the TR above sunspots is higher and probably more extended, and that the opacity of the hydrogen lines is much lower above sunspots, compared to the TR above plage regions. Our result indicates that the enhanced TR emission of the sunspot plume is probably caused by a large filling factor. The strongly enhanced emission at TR temperatures and the reduced continuum ensure that many normally weak TR lines are clearly distinctive in the spectra of sunspot plumes.

Tables 5 and 6 are only available in electronic form at http://www.aanda.org Title: Propagating waves in polar coronal holes as seen by SUMER & EIS Authors: Banerjee, D.; Teriaca, L.; Gupta, G. R.; Imada, S.; Stenborg, G.; Solanki, S. K. Bibcode: 2009A&A...499L..29B Altcode: 2009arXiv0905.1013B Context: To study the dynamics of coronal holes and the role of waves in the acceleration of the solar wind, spectral observations were performed over polar coronal hole regions with the SUMER spectrometer on SoHO and the EIS spectrometer on Hinode.
Aims: Using these observations, we aim to detect the presence of propagating waves in the corona and to study their properties.
Methods: The observations analysed here consist of SUMER spectra of the Ne viii 770 Å line (T = 0.6 MK) and EIS slot images in the Fe xii 195 Å line (T = 1.3 MK). Using the wavelet technique, we study line radiance oscillations at different heights from the limb in the polar coronal hole regions.
Results: We detect the presence of long period oscillations with periods of 10 to 30 min in polar coronal holes. The oscillations have an amplitude of a few percent in radiance and are not detectable in line-of-sight velocity. From the time distance maps we find evidence for propagating velocities from 75 km s-1 (Ne viii) to 125 km s-1 (Fe xii). These velocities are subsonic and roughly in the same ratio as the respective sound speeds.
Conclusions: We interpret the observed propagating oscillations in terms of slow magneto-acoustic waves. These waves can be important for the acceleration of the fast solar wind. Title: The Ly-α profile and center-to-limb variation of the quiet Sun Authors: Curdt, W.; Tian, H.; Teriaca, L.; Schühle, U.; Lemaire, P. Bibcode: 2008A&A...492L...9C Altcode: 2008arXiv0812.1441C Aims: We study the emission of the hydrogen Lyman-α line in the quiet Sun, its center-to-limb variation, and its radiance distribution. We also compare quasi-simultaneous Ly-α and Ly-β line profiles.
Methods: We used the high spectral and spatial resolution of the SUMER spectrometer and completed raster scans at various locations along the disk. For the first time, we used a method to reduce the incoming photon flux to a 20%-level by partly closing the aperture door. We also performed a quasi-simultaneous observation of both Ly-α and Ly-β at the Sun center in sit-and-stare mode. We infer the flow characteristic in the Ly-α map from variations in the calibrated λ 1206 Si iii line centroids.
Results: We present the average profile of Ly-α, its radiance distribution, its center-to-limb behaviour, and the signature of flows on the line profiles. Little center-to-limb variation and no limb brightening are observed in the profiles of the Ly-α line. In contrast to all other lines of the Lyman series, which have a red-horn asymmetry, Ly-α has a robust and - except for dark locations - dominating blue-horn asymmetry. There appears to be a brightness-to-asymmetry relationship. A similar and even clearer trend is observed in the downflow-to-asymmetry relationship. This important result is consistent with predictions from models that include flows. However, the absence of a clear center-to-limb variation in the profiles may be more indicative of an isotropic field than a mainly radial flow.
Conclusions: It appears that the ubiquitous hydrogen behaves in a similar way to a filter that dampens all signatures of the line formation by processes in both the chromosphere and transition region. Title: SUMER observations of the inverse Evershed effect in the transition region above a sunspot Authors: Teriaca, L.; Curdt, W.; Solanki, S. K. Bibcode: 2008A&A...491L...5T Altcode: 2009arXiv0901.3317T Aims: We analyse SUMER spectral scans of a large sunspot within active region NOAA 10923, obtained on 14-15 November 2006, to determine the morphology and dynamics of the sunspot atmosphere at different heights/temperatures.
Methods: The data analysed here consist of spectroheliograms in the continuum around 142.0 nm and in the Si iv 140.2 nm, O iii 70.3 nm, N iv 76.5 nm, and O iv 79.0 nm spectral lines. Gaussian-fitting of the observed profiles provides line-of-sight velocity and Doppler-width maps.
Results: The data show an asymmetric downflow pattern compatible with the presence of the inverse Evershed flow in a region within roughly twice the penumbral radius at transition-region temperatures up to 0.18 MK. The motions, highly inhomogeneous on small scales, seem to occur in a collar of radially directed filamentary structures, with an average width less than the 1 Mm spatial resolution of SUMER and characterised by different plasma speeds. Assuming that the flows are directed along the field lines, we deduce that such field lines are inclined by 10° to 25° with respect to the solar surface. Title: Loop Morphology and Flows and their Relation to the Magnetic Field Authors: Teriaca, L.; Wiegelmann, T.; Lagg, A.; Solanki, S. K.; Curdt, W.; Sekii, T. Bibcode: 2008ASPC..397..196T Altcode: In November 2006 we obtained several rasters of a large sunspot and its trailing region using the SUMER spectrometer on SOHO. The observations consist of spectroheliograms in the continuum around 142 nm and in several spectral lines formed between 80000 K and 0.6 MK, covering the temperature range from the chromosphere to the lower corona. The observed profiles provide LOS velocity and Doppler width maps. TRACE images in the EUV passbands and in the 160 nm continuum provide a clear picture of the coronal loops and the chromosphere near their footpoints. The same target was also observed by all the instruments aboard Hinode and, in particular, by the SOT spectro-polarimeter measuring the photospheric magnetic vector. We combined SOT and MDI data (covering a larger FOV) to infer the coronal magnetic field of the active region by a nonlinear force-free field extrapolation. The observed radiance and velocity patterns at the various heights/temperatures throughout the solar atmosphere are compared with the field topology. Title: The line profile and center-to-limb variation of quiet-Sun Lyman-alpha emission Authors: Curdt, W.; Tian, H.; Teriaca, L.; Schühle, U.; Lemaire, P. Bibcode: 2008ESPM...12.2.91C Altcode: We study the emission of the hydrogen Lyman-alpha line in the quiet Sun, its center-to-limb variation, and its radiance distribution, which we also compare to the Lyman-beta line. We use the high spectral and spatial resolution of the SUMER spectrometer and take raster scans at various locations on the disk. For the first time, we have used a new method to reduce the incoming photon flux to a 20%-level by partly closing the aperture door. We also performed a quasi-simultaneous observation of both Ly-a and Ly-b at Sun centre in sit-and-stare mode. We deduce the flow characteristic in Ly-a map from variations of the calibrated Si III line centroids. We present the average profile of Ly-a, its radiance distribution, its center-to-limb behaviour, and the signature of flows on the line profiles. Different from all other lines of the Lyman series, which have a red-horn asymmetry, Ly-a has a robust and dominating blue-horn asymmetry. To our knowledge, this result is only predicted by models which include flows. Title: Chromospheric Counterparts of UV Explosive Events Authors: Reardon, K.; Cauzzi, G.; Teriaca, L.; Pitterle, M.; Curdt, W. Bibcode: 2008ESPM...12.2.17R Altcode: We present a study of a unique, multi-wavelength dataset of a quiet sun region with the primary goal of studying explosive events at chromospheric and transition region heights. Several hypotheses have been made about the nature of the explosive events, however the underlying mechanisms remain elusive due to their small spatial and temporal scales. Several theoretical models predict an important role for the chromosphere in the triggering of these events.

To shed light on this issue, we have obtained a comprehensive set of simultaneous high spatial, spectral, and temporal resolution observations on April 18, 2007, combining both ground- and space-based observatories. Most importantly, we carried out coordinated observations with SUMER in the transition region Si IV 140.2 nm line together with high-cadence IBIS imaging spectroscopy of the chromospheric CaII 854.2 nm line. This allows us to examine the chromospheric dynamics and acoustic shocks that underlie the transition region events. We also use SOT/NFI magnetograms to examine the relation of the explosive events to the changes in the magnetic topology. The combined dataset also includes Hinode/EIS rasters and Hinode/XRT images that provide information on the higher-temperature coronal response. Title: Helium Line Formation and Abundance during a C-Class Flare Authors: Andretta, Vincenzo; Mauas, Pablo J. D.; Falchi, Ambretta; Teriaca, Luca Bibcode: 2008ApJ...681..650A Altcode: 2008arXiv0803.0418A During a coordinated campaign that took place in 2001 May, a C-class flare was observed both with SOHO instruments and with the Dunn Solar Telescope of the National Solar Observatory at Sacramento Peak. In two previous papers we described the observations and discussed some dynamical aspects of the earlier phases of the flare, as well as the helium line formation in the active region prior to the event. Here we extend the analysis of the helium line formation to the later phases of the flare in two different locations of the flaring area. We have devised a new technique, exploiting all available information from various SOHO instruments, to determine the spectral distribution of the photoionizing EUV radiation produced by the corona overlying the two target regions. In order to find semiempirical models matching all of our observables, we analyzed the effect on the calculated helium spectrum, both of AHe (the He abundance) and of the uncertainties in the incident EUV radiation (level and spectral distribution). We found that the abundance has in most cases (but not in all) a larger effect than the coronal back-radiation. The result of our analysis is that, considering the error of the measured lines and adopting our best estimate for the coronal EUV illumination, the value AHe = 0.075 +/- 0.010 in the chromosphere (for T > 6300 K) and transition region yields reasonably good matches for all the observed lines. This value is marginally consistent with the most commonly accepted photospheric value, AHe = 0.085. Title: Analysis of the Fe X and Fe XIV line width in the solar corona using LASCO-C1 spectral data Authors: Mierla, M.; Schwenn, R.; Teriaca, L.; Stenborg, G.; Podlipnik, B. Bibcode: 2008A&A...480..509M Altcode: 2009arXiv0903.0496M Aims:The purpose of this paper is to analyze the variation in the line width with height in the inner corona (region above 1.1 R⊙), by using the spectral data from LASCO-C1 aboard SOHO. We used data acquired at activity minimum (August-October 1996) and during the ascending phase of the solar cycle (March 1998).
Methods: Series of images acquired at different wavelengths across the Fe X 637.6 nm (red) and Fe XIV 530.3 nm (green) coronal lines by LASCO-C1 allowed us to build radiance and width maps of the off-limb solar corona.
Results: In 1996, the line width of Fe XIV was roughly constant or increased with height up to around 1.3 R⊙ and then it decreased. The Fe X line width increased with height up to the point where the spectra were too noisy to allow line width measurements (around 1.3 R⊙). Fe X showed higher effective temperatures as compared with Fe XIV. In 1998 the line width of Fe XIV was roughly constant with height above the limb (no Fe X data available). Title: Search for photospheric footpoints of quiet Sun transition region loops Authors: Sánchez Almeida, J.; Teriaca, L.; Sütterlin, P.; Spadaro, D.; Schühle, U.; Rutten, R. J. Bibcode: 2007A&A...475.1101S Altcode: 2007arXiv0709.3451S Context: The footpoints of quiet Sun Transition Region (TR) loops do not seem to coincide with the photospheric magnetic structures appearing in traditional low-sensitivity magnetograms.
Aims: We look for the so-far unidentified photospheric footpoints of TR loops using G-band bright points (BPs) as proxies for photospheric magnetic field concentrations.
Methods: We compare TR measurements with SoHO/SUMER and photospheric magnetic field observations obtained with the Dutch Open Telescope.
Results: Photospheric BPs are associated with bright TR structures, but they seem to avoid the brightest parts of the structure. BPs appear in regions that are globally redshifted, but they avoid extreme velocities. TR explosive events are not clearly associated with BPs.
Conclusions: The observations are not inconsistent with the BPs being footpoints of TR loops, although we have not succeeded to uniquely identify particular BPs with specific TR loops. Title: Study of a Solar Streamer on March 1998 using LASCO-C1 Spectral Data Authors: Mierla, M.; Schwenn, R.; Teriaca, L.; Stenborg, G.; Podlipnik, B. Bibcode: 2007AIPC..895...75M Altcode: The slow solar wind is supposed to originate from coronal regions associated with streamers. It is not clear yet how the closed magnetic field structures of streamers are opening up in order to release the plasma. An analysis of this subject, particularly of a streamer on March 1998, is done using LASCO-C1 spectral data. LASCO-C1 is an internally occulted coronagraph on the SOHO spacecraft. It has a tunable Fabry-Perot interferometer which allows taking spectral scans of selected coronal emission lines. From measured line profiles we deduced physical quantities like temperature and flow velocities along the line of sight. This way, we obtained information on the flow pattern in the low corona. Title: T he Lower Transition Region As Seen In The H I Lyman-α Line Authors: Teriaca, L.; Schühle, U.; Solanki, S. K.; Curdt, W.; Marsch, E. Bibcode: 2007ESASP.641E..84T Altcode: The SUMER spectrometer aboard SOHO has been used to acquire several raster images and temporal series of quiet-Sun targets at both disk centre and the limb. Spectra have been recorded simultaneously in the H I Lyman α and the Si III 120.6 nm line. Both spatial and temporal maps of the integrated radiances appear very similar in the two lines, despite the huge difference in optical thickness, a result showing the H I Lyman α to be a good diagnostic of the dynamics and morphology of the lower transition region. Oscillations can be detected and studied at all observed locations. At disk centre, the 3 minute oscillations are sporadically observed in the inter-network but also at locations at the edges of network lanes, while 5 minute oscillations clearly dominate the network. At the limb, evidence of 3 to 5 minute oscillations is found at the base of spicules. Moreover, H I Lyman α spectra shows a high degree of variability, revealing also the signature of explosive events. The combination of high spectral purity images and slit spectra in the H I Lyman α line would therefore be an exceptional new tool to investigate the nature of the solar transition region. This line is therefore of interest for both, a high resolution channel in the EUI instrument and for the EUS spectrometer. Title: T he Lower Transitio n Region As Seen In The H I Lyman-α Line. Authors: Teriaca, L.; Schühle, U.; Solanki, S. K.; Curdt, W.; Marsch, E. Bibcode: 2007ESASP.641E..36T Altcode: The SUMER spectrometer aboard SOHO has been used to acquire several raster images and temporal series of quiet-Sun targets at both disk centre and the limb. Spectra have been recorded simultaneously in the H I Lyman α and the Si III 120.6 nm line. Both spatial and temporal maps of the integrated radiances appear very similar in the two lines, despite the huge difference in optical thickness, a result showing the H I Lyman α to be a good diagnostic of the dynamics and morphology of the lower transition region. Oscillations can be detected and studied at all observed locations. At disk centre, the 3 minute oscillations are sporadically observed in the inter-network but also at locations at the edges of network lanes, while 5 minute oscillations clearly dominate the network. At the limb, evidence of 3 to 5 minute oscillations is found at the base of spicules. Moreover, H I Lyman α spectra shows a high degree of variability, revealing also the signature of explosive events. The combination of high spectral purity images and slit spectra in the H I Lyman α line would therefore be an exceptional new tool to investigate the nature of the solar transition region. This line is therefore of interest for both, a high resolution channel in the EUI instrument and for the EUS spectrometer. Title: T hin Silicon Carbide Coating Of The Primary Mirror Of VUV Imaging Instruments Of Solar Orbiter Authors: Schühle, U.; Uhlig, H.; Curdt, W.; Feigl, T.; Theissen, A.; Teriaca, L. Bibcode: 2007ESASP.641E..83S Altcode: We investigate the thermo-optical and vacuum- ultraviolet properties of thin silicon carbide (SiC) coatings on transparent substrates in view of their use for Solar Orbiter remote sensing VUV instrumentation. We have made experimental studies with thin SiC coatings on quartz plates to evaluate their reflective properties in the VUV spectral range between 58 nm and 123 nm. We discuss the results in relation to the visible and near infrared optical properties of the samples. A thin SiC coating of 10 nm thickness is shown to be a very promising compromise between high VUV reflectivity and low vis/IR absorption. The overall absorption of the solar spectrum by such a mirror is less than 8 %. This will be beneficial for instruments requiring a large aperture due to diffraction and radiometric limitation, in coping with the thermal heat load during the Solar Orbiter mission. As an example, we propose a design of the primary telescope mirror for the Extreme Ultraviolet Spectrometer (EUS). Title: EUI, The Ultraviolet Imaging Telescopes Of Solar Orbiter Authors: Hochedez, J. -F.; Appourchaux, T.; Defise, J. -M.; Harra, L. K.; Schühle, U.; Auchère, F.; Curdt, W.; Hancock, B.; Kretzschmar, M.; Lawrence, G.; Leclec'h, J. -C.; Marsch, E.; Mercier, R.; Parenti, S.; Podladchikova, E.; Ravet, M. -F.; Rochus, P.; Rodriguez, L.; Rouesnel, F.; Solanki, S.; Teriaca, L.; Van Driel, L.; Vial, J. -C.; Winter, B.; Zhukov, A. Bibcode: 2007ESASP.641E..33H Altcode: The scientific objectives of Solar Orbiter rely ubiquitously on EUI, its suite of solar atmosphere imaging telescopes. In the configuration discussed here, EUI includes three co-aligned High Resolution Imagers (HRI) and one Full Sun Imager (FSI). FSI and two HRIs observe in extreme ultraviolet passbands, dominated by coronal emission. Another HRI is designed for the hydrogen Lyman α radiation in the far UV, imaging the Chromosphere and the lower Transition Region. The current EUI design and some of its development challenges are highlighted. EUI profits from co-rotation phases, solar proximity and departure from the ecliptic. In synergy with the other S.O. payload, EUI probes the dynamics of the solar atmosphere, provides context data for all investigations and helps to link in-situ and remote-sensing observations. In short, it serves all four top-level goals of the mission. For these reasons, the EUI suite is keenly anticipated in the European scientific community and beyond. Title: The dynamics of the minimum solar corona during the period August October 1996 Authors: Mierla, M.; Schwenn, R.; Teriaca, L.; Stenborg, G.; Podlipnik, B. Bibcode: 2007AdSpR..40.1049M Altcode: The paper presents the dynamics of the solar corona at the minimum phase of the solar cycle (period August-October 1996), as inferred from LASCO-C1 spectral data. LASCO-C1 is an internally occulted coronagraph aboard the SOHO spacecraft. It has a tunable Fabry-Pérot interferometer which allows taking spectral scans of selected coronal emission lines. From measured line profiles we deduced physical quantities such as temperature and flow velocities along the line of sight. This way, we obtained information on the flow pattern in the low corona (1.1-1.6 solar radii). Title: LASCO-C1 Spectral Analysis of Flows in the Inner Corona Authors: Mierla, Marilena; Schwenn, Rainer; Teriaca, Luca; Stenborg, Guillermo; Podlipnik, Borut Bibcode: 2007RoAJ...17..167M Altcode: No abstract at ADS Title: The Evaporation Regime in a Confined Flare Authors: Falchi, A.; Teriaca, L.; Maltagliati, L. Bibcode: 2006SoPh..239..193F Altcode: 2006SoPh..tmp...87F We studied the evolution of a small eruptive flare (GOES class C1) from its onset phase using multi-wavelength observations that sample the flare atmosphere from the chromosphere to the corona. The main instruments involved were the Coronal Diagnostic Spectrometer (CDS) aboard SOHO and facilities at the Dunn Solar Tower of the National Solar Observatory/Sacramento Peak. Transition Region and Coronal Explorer (TRACE) together with Ramaty High-Energy Spectroscopic Imager (RHESSI) also provided images and spectra for this flare. Hα and TRACE images display two loop systems that outline the pre-reconnection and post-reconnection magnetic field lines and their topological changes revealing that we are dealing with an eruptive confined flare. RHESSI data do not record any detectable emission at energies ≥25 keV, and the observed count spectrum can be well fitted with a thermal plus a non-thermal model of the photon spectrum. A non-thermal electron flux F ≈ 5 × 1010 erg cm−2 s−1 is determined. The reconstructed images show a very compact source whose peak emission moves along the photospheric magnetic inversion line during the flare. This is probably related to the motion of the reconnection site, hinting at an arcade of small loops that brightens successively. The analysis of the chromospheric spectra (Ca II K, He I D3 and Hγ, acquired with a four-second temporal cadence) shows the presence of a downward velocity (between 10 and 20 km s−1) in a small region intersected by the spectrograph slit. The region is included in an area that, at the time of the maximum X-ray emission, shows upward motions at transition region (TR) and coronal levels. For the He I 58.4 and O V 62.97 lines, we determine a velocity of ≈−40 km s−1 while for the Fe XIX 59.22 line a velocity of ≈−80 km s−1 is determined with a two-component fitting. The observations are discussed in the framework of available hydrodynamic simulations and they are consistent with the scenario outlined by Fisher (1989). No explosive evaporation is expected for a non-thermal electron beam of the observed characteristics, and no gentle evaporation is allowed without upward chromospheric motion. It is suggested that the energy of non-thermal electrons can be dissipated to heat the high-density plasma, where possibly the reconnection occurs. The consequent conductive flux drives the evaporation process in a regime that we can call sub-explosive. Title: Dynamics and evolution of an eruptive flare Authors: Teriaca, L.; Falchi, A.; Falciani, R.; Cauzzi, G.; Maltagliati, L. Bibcode: 2006A&A...455.1123T Altcode: 2009arXiv0903.0232T Aims.We study the dynamics and the evolution of a C2.3 two-ribbon flare, developed on 2002 August 11, during the impulsive phase as well as during the long gradual phase. To this end we obtained multiwavelength observations using the CDS spectrometer aboard SOHO, facilities at the National Solar Observatory/Sacramento Peak, and the TRACE and RHESSI spacecrafts.
Methods: .CDS spectroheliograms in the Fe xix, Fe xvi, O v and He i lines allow us to determine the velocity field at different heights/temperatures during the flare and to compare them with the chromospheric velocity fields deduced from Hα image differences. TRACE images in the 17.1 nm band greatly help in determining the morphology and the evolution of the flaring structures.
Results: .During the impulsive phase a strong blue-shifted Fe xix component (-200 km s-1) is observed at the footpoints of the flaring loop system, together with a red-shifted emission of O v and He i lines (20 km s-1). In one footpoint simultaneous Hα data are also available and we find, at the same time and location, downflows with an inferred velocity between 4 and 10 km s-1. We also verify that the "instantaneous" momenta of the oppositely directed flows detected in Fe xix and Hα are equal within one order of magnitude. These signatures are in general agreement with the scenario of explosive chromospheric evaporation. Combining RHESSI and CDS data after the coronal upflows have ceased, we prove that, independently from the filling factor, an essential contribution to the density of the post-flare loop system is supplied from evaporated chromospheric material. Finally, we consider the cooling of this loop system, that becomes successively visible in progressively colder signatures during the gradual phase. We show that the observed cooling behaviour can be obtained assuming a coronal filling factor of ≈0.2 to 0.5.
Title: Helium Line Formation During the Decay Phase of a Small Two-Ribbon Flare Authors: Andretta, V.; Mauas, P. J. D.; Falchi, A.; Teriaca, L. Bibcode: 2006ESASP.617E.151A Altcode: 2006soho...17E.151A No abstract at ADS Title: The Dynamic Nature of the Lower Transition Region as Revealed by Spectroscopy of the Hydrogen Lyman-α Line Authors: Teriaca, L.; Schühle, U.; Solanki, S. K.; Curdt, W.; Marsch, E. Bibcode: 2006ESASP.617E..77T Altcode: 2006soho...17E..77T No abstract at ADS Title: Prominence Parameters Derived from Hydrogen Lyman-α Spectral Profiles Measured by SOHO/SUMER Authors: Gunár, S.; Teriaca, L.; Heinzel, P.; Schühle, U. Bibcode: 2006ESASP.617E..63G Altcode: 2006soho...17E..63G No abstract at ADS Title: Rhessi Images and Spectra of Two Small Flares Authors: Maltagliati, L.; Falchi, A.; Teriaca, L. Bibcode: 2006SoPh..235..125M Altcode: 2005astro.ph..8490M We studied the evolution of two small flares (GOES class C2 and C1) that developed in the same active region with different morphological characteristics: one is extended and the other is compact. We analyzed the accuracy and the consistency of different algorithms implemented in Reuven Ramaty High-Energy Spectroscopic Imager (RHESSI) software to reconstruct the image of the emitting sources, for energies between 3 and 12 keV. We found that all tested algorithms give consistent results for the peak position, while the other parameters can differ at most by a factor 2. Pixon and Forward-fit generally converge to similar results but Pixon is more reliable for reconstructing a complex source. We investigated the spectral characteristics of the two flares during their evolution in the 3-25 keV energy band. We found that a single thermal model of the photon spectrum is inadequate to fit the observations and we needed to add either a non-thermal model or a hot thermal one. The non-thermal and the double thermal fits are comparable. If we assume a non-thermal model, the non-thermal energy is always higher than the thermal one. Only during the very final decay phase a single thermal model fits the observed spectrum fairly well. Title: LASCO-C1 Spectral Data Analysis of the Slow Solar Wind Authors: Mierla, M.; Schwenn, R.; Teriaca, L.; Podlipnik, B.; Stenborg, G. Bibcode: 2005ESASP.600E..45M Altcode: 2005dysu.confE..45M; 2005ESPM...11...45M No abstract at ADS Title: The Dynamics of the Lower Transition Region as Inferred from Spectroscopy of the Hydrogen LYMAN-α Line Authors: Teriaca, L.; Schühle, U.; Solanki, S. K.; Curdt, W.; Marsch, E. Bibcode: 2005ESASP.600E.100T Altcode: 2005ESPM...11..100T; 2005dysu.confE.100T No abstract at ADS Title: The Structure of the Lower Transition Region as Inferred from the Hydrogen LYMAN-α Line Radiance Authors: Teriaca, L.; Schühle, U.; Solanki, S. K.; Curdt, W.; Marsch, E. Bibcode: 2005ESASP.596E..66T Altcode: 2005ccmf.confE..66T No abstract at ADS Title: The widths of vacuum-ultraviolet spectral lines in the equatorial solar corona observed with CDS and SUMER Authors: Wilhelm, K.; Fludra, A.; Teriaca, L.; Harrison, R. A.; Dwivedi, B. N.; Pike, C. D. Bibcode: 2005A&A...435..733W Altcode: Observations of the solar equatorial corona between heights of 36 Mm and 184 Mm above the limb obtained by the SOHO spectrometers CDS and SUMER in December 2003 are presented and discussed with special emphasis on the widths of the spectral lines Mg x at 62.50 nm, Al xi at 55.00 nm and 56.82 nm, Ca x at 55.78 nm, and Si xi at 58.09 nm. SUMER observed, in addition, the lines Mg x 60.98 nm, Ca x 57.40 nm, Fe xii 124.20 nm, Fe xvii 115.31 nm, and Ca xiii 113.37 nm. The Si xii 52.11 nm line was only observed by CDS. A different behaviour of the line width of Mg x 62.50 nm as a function of height above the limb had been found in studies carried out independently with both instruments at different times. It is the aim of this joint investigation to (a) study instrumental effects on line-width results; and (b) provide a thorough analysis of line profiles with altitude for the new campaign. Title: Helium line formation in a solar active region Authors: Mauas, P. J. D.; Andretta, V.; Falchi, A.; Falciani, R.; Teriaca, L.; Cauzzi, G. Bibcode: 2005ESASP.560..811M Altcode: 2005csss...13..811M No abstract at ADS Title: Helium Line Formation and Abundance in a Solar Active Region Authors: Mauas, P. J. D.; Andretta, V.; Falchi, A.; Falciani, R.; Teriaca, L.; Cauzzi, G. Bibcode: 2005ApJ...619..604M Altcode: 2004astro.ph.12058M An observing campaign (SOHO JOP 139), coordinated between ground-based and Solar and Heliospheric Observatory (SOHO) instruments, has been planned to obtain simultaneous spectroheliograms of the same active region in several spectral lines. The chromospheric lines Ca II K, Hα, and Na I D, as well as He I 10830, 5876, 584, and He II 304 Å lines have been observed. The EUV radiation in the range λ<500 Å and in the range 260<λ<340 Å has also been measured at the same time. These simultaneous observations allow us to build semiempirical models of the chromosphere and low transition region of an active region, taking into account the estimated total number of photoionizing photons impinging on the target active region and their spectral distribution. We obtained a model that matches very well all the observed line profiles, using a standard value for the He abundance ([He]=0.1) and a modified distribution of microturbulence. For this model we study the influence of the coronal radiation on the computed helium lines. We find that, even in an active region, the incident coronal radiation has a limited effect on the UV He lines, while it is of fundamental importance for the D3 and 10830 Å lines. Finally, we build two more models, assuming values of He abundance [He]=0.07 and 1.5, only in the region where temperatures are >1×104 K. This region, between the chromosphere and transition region, has been indicated as a good candidate for processes that might be responsible for strong variations of [He]. The set of our observables can still be well reproduced in both cases, changing the atmospheric structure mainly in the low transition region. This implies that, to choose between different values of [He], it is necessary to constrain the transition region with different observables, independent of the He lines. Title: Dynamics of the Solar Corona Using LASCO-C1 Spectral Data Authors: Mierla, Marilena; Schwenn, Rainer; Teriaca, Luca; Stenborg, Guillermo; Podlipnik, Borut Bibcode: 2005RoAJ...15..137M Altcode: No abstract at ADS Title: Using LASCO-C1 spectroscopy for coronal diagnostics Authors: Mierla, M.; Schwenn, R.; Teriaca, L.; Stenborg, G.; Podlipnik, B. Bibcode: 2005AdSpR..35.2199M Altcode: The LASCO-C1 telescope was designed to perform spectral analysis of coronal structures by means of a tunable Fabry-Pérot interferometer acquiring images at different wavelengths. Results from spectral scans of the Fe XIV 5303 Å green coronal emission line are presented. Physical quantities like the ion temperature (line widths), and the flow velocity along the line of sight (Doppler shifts) are obtained over the entire corona. Title: Overview of AN Eruptive Flare: from Chromospheric Evaporation to Cooling of Hot Flaring Loops Authors: Teriaca, L.; Maltagliati, L.; Falchi, A.; Falciani, R.; Cauzzi, G. Bibcode: 2004ESASP.575..265T Altcode: 2004soho...15..265T No abstract at ADS Title: Transition region small-scale dynamics as seen by SUMER on SOHO Authors: Teriaca, L.; Banerjee, D.; Falchi, A.; Doyle, J. G.; Madjarska, M. S. Bibcode: 2004A&A...427.1065T Altcode: High spectral, spatial and temporal resolution UV observations of the quiet Sun transition region show a highly structured and dynamical environment where transient supersonic flows are commonly observed. Strongly non-Gaussian line profiles are the spectral signatures of these flows and are known in the literature as explosive events. In this paper we present a high spatial resolution (≈ 1'') spectroheliogram of a 273''× 291'' area of the quiet Sun acquired with SUMER/SOHO in the O VI spectral line at λ103.193 nm. The extremely high quality of these observations allows us to identify tens of explosive events from which we estimate an average size of 1800 km and a birthrate of 2500 s-1 over the entire Sun. Estimates of the kinetic and enthalpy fluxes associated with these events show that explosive events are not important as far as solar coronal heating is concerned. The relationship with the underlying photospheric magnetic field is also studied, revealing that explosive events generally occur in regions with weak (and, very likely, mixed polarity) magnetic flux. By studying the structure of upward and downward flows exceeding those associated to average quiet Sun profiles, we find a clear correlation between the ``excess'' flows and the magnetic network. However, although explosive events are always associated with flow patterns often covering areas larger than the explosive event itself, the contrary is not true. In particular, almost all flows associated with the stronger concentrations of photospheric magnetic flux do not show non-Gaussian line profiles. In some cases, non-Gaussian line profiles are associated with supersonic flows in small magnetic loops. The case of a small loop showing a supersonic siphon-like flow of ≈130 km s-1 is studied in detail. This is, to our knowledge, the first detection of a supersonic siphon-like flow in a quiet Sun loop. In other cases, the flow patterns associated with explosive events may suggest a relation with UV spicules. Title: On the widths of the Mg X lines near 60 nm in the corona Authors: Wilhelm, K.; Dwivedi, B. N.; Teriaca, L. Bibcode: 2004A&A...415.1133W Altcode: We examine the line widths of both components of the Mg X 2s 2S1/2-2p 2P1/2,3/2 doublet at 60.98 nm and 62.50 nm in the low corona of the quiet Sun, and find that the Doppler width (i.e. half 1/e width) broadens from Δ λD ≈ 8.2 pm to ≈9.5 pm (with an estimated relative standard uncertainty of 4%) between the limb and 220 Mm above the limb in the equatorial corona. In a polar coronal hole, the Doppler width increases from 10.8 pm near 30 Mm to 11.4 pm at around 80 Mm. The analysis does not provide any evidence for a narrowing of the emission-line profiles as a function of the distance from the solar limb. Title: SUMER, UVCS and LASCO Observations of Small-Scale Ejecta Authors: Teriaca, L.; Curdt, W.; Poletto, G. Bibcode: 2004ESASP.547..291T Altcode: 2004soho...13..291T During the fall 2002 SOHO-Sun-Ulysses quadrature, coordinated SUMER/UVCS observations were carried out off the west limb. Data were acquired over six consecutive days in several lines formed in the 2 104 - 106 K temperature range. The center of the SUMER slit was placed around 1.13 R and oriented in the north south direction, while the UVCS slit was set tangent to the solar limb at altitudes ranging between 1.6 and 2.1 R. On 19 and 20 November SUMER observed repeated transient events characterized by a strong increase of the intensity of transition region and Hydrogen Lyman and lines with large line broadenings and line of sight velocities, while little if any variation is seen in lines formed around 106 K. The duration of these events varies between 10-15 minutes up to 1 hour. The SUMER events are associated to streamer-like outflows seen in LASCO images and, in the case of the larger 19 November event, with a small jet travelling at ~400 km/s across the LASCO C2 fiel of view. Title: Dynamic properties of the solar corona: SOHO/LASCO observations Authors: Mierla, M.; Schwenn, R.; Stenborg, G.; Teriaca, L.; Podlipnik, B. Bibcode: 2004cosp...35.2275M Altcode: 2004cosp.meet.2275M With the launch of the SOHO spacecraft in December 1995, the quality of corona observations has improved significantly. The LASCO instruments with their field of view now extending from 1.1 Rs (C1) to 30 Rs (C3) offer sufficient sensitivity to make an almost continuous outflow in the streamer belt visible. We report on two different approaches to study the plasma motion, both in the plane of the sky and along the line of sight. 1. By means of a multi-resolution image processing technique based on wavelet packets the boundaries and the internal details of originally faint and diffuse structures are enhanced. This approach allows unambiguous image interpretation and provides a means for the quantification of stationary and dynamic coronal structures required for conducting morphological studies. 2. The LASCO/C1 telescope was designed to perform spectral analysis on coronal structures. The tunable Fabry-Perot interferometer allows to obtain images at different wavelengths. Results from spectral scans of the coronal green and red emission lines are presented. From the line profiles physical quantities like temperatures (from line widths), and flow velocities (from Doppler shifts) along the line of sight are deduced. Title: Line Shift Variations in Solar Transition Region Lines Authors: Doyle, J. G.; Madjarska, M.; Giamikakis, J.; Teriaca, L.; Roussev, I. Bibcode: 2003csss...12..619D Altcode: Two high time cadence datasets, taken in C III 977Å and O VI 1032Å were analysed in an effort to establish the extent of the variability in the Doppler-shift of typical mid-transition region lines. In C III, the shortest time-scale variability seems to occur in the network boundary regions where the line-shift can vary by 7-8 km s-1 in less than 1 min. The internetwork region also shows variability although this tends to be longer lived, ∼2-3 mins. The average C III line-shift in all regions is for a red-shift of ∼ 8 km s-1 in very good agreement with that derived by others. Furthermore, there does not seem to be any obvious difference in the average line-shift in network and internetwork regions. On a few rare occasions, the C III line was blue-shifted. The O VI line was also red-shifted with the network region showing evidence for a periodicity. These observations were compared to model line profiles based on the response of a 2D MHD environment representing the solar transition region to micro-scale energy depositions. A variety of temperatures at which the energy deposition takes place as well as the amount of energy deposited was examined. Title: Solar wind acceleration in low density regions Authors: Teriaca, L.; Poletto, G.; Romoli, M.; Biesecker, D. Bibcode: 2003AIPC..679..327T Altcode: High speed solar wind is known to originate in polar coronal holes which, however, are made up of two components: bright, high density regions known as plumes, and dark, weakly emitting low density regions known as interplumes. Recent space observations have shown that the width of UV lines is larger in interplume regions [see e.g. 1, 2] while observations of the ratio of the O VI doublet lines at 1032 and 1037 Å, at the altitude of 1.7 solar radii, suggest higher outflows in interplume regions than in plumes [3]. These results seem to locate the source of the fast solar wind in the interplume regions. The present work aims at identifying the outflow speed vs. altitude profile of the O VI ions, at heights up to 2 solar radii, both in plumes and interplume regions. To this end, we examined SUMER and UVCS data taken in the North polar coronal hole on June 3, 1996 over the altitude range between 1 and 2 solar radii. A Doppler dimming analysis applied to our data allows us to determine the outflow speed in interplume regions throughout the range covered by the observations. Our results favor interplumes as sources of fast wind. However, models mimicking observations in plume regions will also be discussed. Title: The Nascent Solar Wind: Origin and Acceleration Authors: Teriaca, Luca; Poletto, Giannina; Romoli, Marco; Biesecker, Doug A. Bibcode: 2003ApJ...588..566T Altcode: High-speed solar wind is known to originate in polar coronal holes, which, however, are made up of two components: bright, high-density regions known as ``plumes'' and dark, weakly emitting low-density regions known as ``interplumes.'' Recent space observations have shown that the width of UV lines is larger in interplume regions, while observations of the ratio of the O VI doublet lines at 1032 and 1037 Å, at 1.7 solar radii, suggest higher outflows in interplume regions than in plumes at that altitude. These results favor interplume regions as sources of the fast solar wind. The present work aims at investigating the outflow speed versus altitude properties of the O VI and H I ions, at heights below 2 solar radii, in both plumes and interplume regions. To this end, we examined Solar Ultraviolet Measurement of Emitted Radiation (SUMER) and Ultraviolet Coronagraph Spectrometer (UVCS) observations of a north polar coronal hole taken on 1996 June 3, over the altitude range between 1 and 2 solar radii, and through a Doppler dimming analysis of our data, we show that interplume areas may be really identified as sources of fast wind streams. The behavior of plumes, on the contrary, can be interpreted in terms of static structures embedded in the interplume ambient. We conclude by comparing our results with the predictions of theoretical models of the solar wind and giving an empirical estimate of the heating rate, per particle, for H I and O VI ions in interplume regions at 1.75 and 2.0 solar radii. Title: Solar and Heliospheric Observatory/Coronal Diagnostic Spectrograph and Ground-based Observations of a Two-Ribbon Flare: Spatially Resolved Signatures of Chromospheric Evaporation Authors: Teriaca, L.; Falchi, A.; Cauzzi, G.; Falciani, R.; Smaldone, L. A.; Andretta, V. Bibcode: 2003ApJ...588..596T Altcode: During a coordinated observing campaign (Solar and Heliospheric Observatory, SOHO JOP 139), we obtained simultaneous spectroheliograms of a solar active region in several spectral lines, sampling levels from the chromosphere to the corona. Ground-based spectroheliograms were acquired at the Dunn Solar Tower of the National Solar Observatory/Sacramento Peak in four chromospheric lines, while the coronal diagnostic spectrograph on board SOHO was used to obtain rasters of the active region in transition region (TR) and coronal lines. Such a complete data set allowed us to compare the development of intensity and velocity fields during a small two-ribbon flare in the whole atmosphere. In particular, we obtained for the first time quasi-simultaneous and spatially resolved observations of velocity fields during the impulsive phase of a flare, in both the chromosphere and upper atmosphere. In this phase, strong downflows (up to 40 km s-1) following the shape of the developing ribbons are measured at chromospheric levels, while strong upward motions are instead measured in TR (up to -100 km s-1) and coronal lines (-160 km s-1). The spatial pattern of these velocities have a common area about 10" wide. This is the first time that opposite-directed flows at different atmospheric levels are observed in the same spatial location during a flare. These signatures are highly suggestive of the chromospheric evaporation scenario predicted in theoretical models of flares. Title: An EUV Bright Point as seen by SUMER, CDS, MDI and EIT on-board SoHO Authors: Madjarska, M. S.; Doyle, J. G.; Teriaca, L.; Banerjee, D. Bibcode: 2003A&A...398..775M Altcode: This paper presents the formation, evolution and decay of a coronal bright point via a spectroscopic analysis of its transition region counterpart and the evolution of the underlying magnetic bipole during 3 days of almost continuous observations. The data were obtained with various instruments on-board SoHO, including the SUMER spectrograph in the transition region line S VI 933.40 Å, CDS in the He I 584.33, O V 629.73 and Mg IX 368.06 Å lines, plus MDI and EIT. The existence of the coronal feature is strongly correlated with the evolution of the underlying bipolar region. The lifetime of the bright point from the moment when it was first visible in the EIT images until its complete disappearance was ~ 18 hrs. Furthermore, the bright point only became visible at coronal temperatures when the two converging opposite magnetic polarities were ~ 7000 km apart. As far as the temporal coverage of the data permits, we found that the bright point disappeared at coronal temperatures after a full cancellation of one of the magnetic polarities. The spectroscopic analysis reveals the presence of small-scale ( ~ 6 arcsec) transient brightenings within the bright point with a periodicity of ~ 6 min. The Doppler shift in the bright point was found to be in the range of -10 to 10 km ; s-1 although it is dominated by a red-shifted emission which is associated with regions characterized by stronger ``quiet'' Sun photospheric magnetic flux. Small-scale brightenings within the bright point show velocity variations in the range 3-6 km ; s-1. In general the bright point has a radiance ~ 4 times higher than that of the network. No relation was found between the bright point and the UV explosive event phenomena. Title: Interplume as source of the fast solar wind Authors: Teriaca, L.; Poletto, G.; Romoli, M.; Biesecker, D. A. Bibcode: 2003MmSAI..74..713T Altcode: High speed solar wind is known to originate in polar coronal holes which, however, are made up of two components: bright, high density regions known as plumes and dark, weakly emitting low density regions known as interplumes. Recent space observations have shown that the width of UV lines is larger in interplume regions. Moreover, observations of the ratio of the O VI doublet lines at 1032 and 1037 Å, at 1.7 Rsun, suggest higher outflows in interplume regions than in plumes at that altitude. In this work we examine SUMER and UVCS observations of a north polar coronal hole taken on 1996 June 3, over the altitude range between 1 and 2 Rsun and, through a Doppler dimming analysis of our data, we show that interplume areas may be really identified as sources of fast wind streams. The behavior of plumes, on the contrary, can be interpreted in terms of static structures embedded in the interplume ambient. We conclude comparing our results with the predictions of theoretical models of the solar wind. Title: Spatially resolved signatures of chromospheric evaporation during a small two-ribbon flare Authors: Teriaca, L.; Falchi, A.; Cauzzi, G.; Falciani, R.; Smaldone, L. A.; Andretta, V. Bibcode: 2003MmSAI..74..635T Altcode: Ground based spectroheliograms of a solar active region were acquired in four chromospheric lines simultaneously with rasters in transition region (TR) and coronal lines obtained with the Coronal Diagnostic Spectrograph (CDS) aboard SOHO. Such a complete dataset allows us to study the development of intensity and velocity fields during a small two-ribbon flare in the whole atmosphere. In particular, we obtain for the first time quasi-simultaneous and spatially resolved observations of velocity fields during the impulsive phase of a flare, both in chromosphere and upper atmosphere. In this phase, strong downflows (up to 40 km s-1) following the shape of the developing ribbons are measured at chromospheric levels, while strong upward motions are measured in TR (up to -100 km s-1) and coronal lines (-160 km s-1). The spatial pattern of these velocities have a common area about 10 arcsec wide. This is the first time that opposite directed flows at different atmospheric levels are observed in the same spatial location during a flare. These signatures are highly suggestive of the chromospheric evaporation scenario predicted in theoretical models of flares. Title: Behaviour of Hydrogen Lyman lines in a prominence region from SUMER and CDS Authors: Aznar Cuadrado, R.; Andretta, V.; Teriaca, L.; Kucera, T. A. Bibcode: 2003MmSAI..74..611A Altcode: We present observations of a prominence, taken on 1998 February 20 in the framework of SOHO Joint Observing Program no. 63. The instruments involved were SUMER and the NIS Spectrograph of CDS. The SUMER spectral range includes the hydrogen Lyman series - starting from Ly-epsilon - down to the head of the Lyman continuum, while CDS observed a number of lines from T ~ 104 K to T ~ 2x 106 K. For these observations, we were able to obtain a satisfactory determination of the pointing of the SUMER slit relative to CDS. We thus examined - and compared with information from CDS spectra - the main characteristics of the hydrogen Lyman series lines and of other strong lines in the SUMER spectral interval. We also studied the properties (depth, asymmetry) of the central reversal present in several or all of the Lyman lines in some regions of the prominence. Title: Chromospheric and Transition region He lines during a flare Authors: Falchi, A.; Mauas, P. J. D.; Andretta, V.; Teriaca, L.; Cauzzi, G.; Falciani, R.; Smaldone, L. A. Bibcode: 2003MmSAI..74..639F Altcode: An observing campaign (SOHO JOP 139), coordinated between ground based and SOHO instruments, has been planned to obtain simultaneous spectroheliograms of the same area in several spectral lines. The chromospheric lines Ca II K, Hα and Na I D as well as He I 10830, 5876, 584 and 304 Ålines have been observed. These observations allow us to build semi-empirical models of the atmosphere before and during a small flare. With these models, constructed to match the observed line profiles, we can test the He abundance value. Title: Transition region small-scale dynamics: UV explosive events Authors: Teriaca, L.; Falchi, A.; Doyle, J. G.; Madjarska, M. S.; Banerjee, D. Bibcode: 2002ESASP.506..777T Altcode: 2002ESPM...10..777T; 2002svco.conf..777T High spectral, spatial and temporal resolution UV observations of the quiet Sun transition region show a highly structured and dynamical environment where transient events such as brightenings, blinkers and explosive events occur continuously. In particular explosive events are characterized by strongly non-Gaussian line profiles witnessing velocities up to 200 km s-1. The high kinetic and enthalpy fluxes associated with these events could be important in the energy balance of the transition region and, perhaps, of the whole corona. In this paper we present a high spatial resolution (~1") spectroheliogram of a 270×290 arcsec2 wide area of the quiet Sun acquired with SUMER/SoHO in the O VI 1032 spectral line. The extremely high quality of these observations allows us to identify tens of explosive events and to study their relationship with the underlying photospheric magnetic field. Moreover, the behaviour of lines emitted by plasma at chromospheric (2×104K) and coronal (106K) temperatures during transition region explosive events is investigated. We conclude that those events do not contribute significantly to the energy balance of the corona and seems typical of structure not obviously connected to the T≥106K corona. Title: SUMER observations of hydrogen Lyman series and continuum in a prominence Authors: Andretta, Vincenzo; Aznar Cuadrado, Regina; Kucera, Therese A.; Teriaca, Luca Bibcode: 2002ESASP.506..419A Altcode: 2002svco.conf..419A; 2002ESPM...10..419A We present observations of a prominence, taken on February 20, 1998 in the framework of SOHO Joint Observing Program no. 63. The instruments involved were SUMER and the Normal Incidence Spectrograph (NIS) of CDS. The SUMER spectral range includes the hydrogen Lyman series - starting from Ly-ɛ - down to the head of the Lyman continuum, while CDS observed a number of lines from T ~ 104K to T ~ 2×106K. For these observations, we were able to obtain a satisfactory determination of the pointing of the SUMER slit relative to CDS. We thus examined - and compared with information from CDS spectra - the main characteristics of the hydrogen Lyman series lines and of other strong lines in the SUMER spectral interval. We also studied the properties (depth, asymmetry) of the central reversal present in several or all of the Lyman lines in some regions of the prominence. Title: Temporal variability in the Doppler-shift of solar transition region lines Authors: Doyle, J. G.; Madjarska, M. S.; Roussev, I.; Teriaca, L.; Giannikakis, J. Bibcode: 2002A&A...396..255D Altcode: High cadence datasets taken in C III 977 Å, O VI 1032 Å and Ne VIII 720 Å were analysed in an effort to establish the extent of the variability in the Doppler-shift of typical mid-transition region lines. The shortest time-scale variability seems to occur in the network boundary regions where the line-shift can vary by 7-8 km s-1 in less than 1 min. The internetwork region also shows variability although this tends to be longer lived, ~ 2-3 min. The average line-shift in C III is a red-shift which ranges from ~ 2 km s-1 to ~ 20 km s-1 with an average value for all regions selected being around 10 km s-1 in very good agreement with that derived by others. The red-shift values indicate a clear difference between network and internetwork regions, with the largest red-shift being present at the network boundary. For O VI, this gives an average red-shift ranging from 5 to 10 km s-1. For Ne VIII, there is a 13 km s-1 difference between internetwork and bright network plasma with the bright network being more red-shifted. This could imply that the bright network regions are dominated by spicule down-flow.\ In the second part we present results from 2-dimensional (2D) dissipative magnetohydrodynamic (MHD) simulations of the response of the solar transition region to micro-scale energy depositions. A variety of temperatures at which the energy deposition takes place as well as the amount of energy deposited are examined. This work is a continuation of previous related simulations where small-scale energy depositions were modelled in 1D hydrodynamics. The observable consequences of such transient events are then computed for three transition region lines, namely C IV 1548 Å, O VI 1032 Å, and Ne VIII 770 Å, under the consideration of non-equilibrium ionization. Title: Chromospheric evaporation in a two-ribbon flare Authors: Cauzzi, G.; Falchi, A.; Teriaca, L.; Falciani, R.; Smaldone, L. A.; Andretta, V. Bibcode: 2002ESASP.506..561C Altcode: 2002ESPM...10..561C; 2002svco.conf..561C We present simultaneous, spatially and temporally resolved chromospheric, transition region and coronal observations of a small eruptive flare studied throughout its whole development. We show that strong and co-spatial plasma motions, oppositely directed in the chromosphere (downflows) and in upper atmospheric layers (upflows), develop at the onset of the flare. For the first time, we prove that such oppositely directed flows originate from the same flaring kernels in different atmospheric layers. Using realistic values for the plasma parameters in the flaring loop, we also estimate a balance between the upward and downward momenta. Our observations confirm in a very convincing way the scenario of chromospheric evaporation predicted in theoretical models of flares. Title: Transition region explosive events: Do they have a coronal counterpart? Authors: Teriaca, L.; Madjarska, M. S.; Doyle, J. G. Bibcode: 2002A&A...392..309T Altcode: EUV explosive events are a prominent class of phenomena characterizing the solar transition region. Their correct location in the wider frame-work of the outer solar atmosphere can provide important insight on the nature of the transition region itself and its relationship with the hotter corona and the cooler chromosphere. In this paper we present new high-cadence SUMER observations of the ``quiet'' Sun obtained simultaneously in the mid-transition region N V 1238.8 Å line (1.8x 105 K) and in the coronal Mg X 625 Å line (1.1x 106 K). These observations are aimed at providing information on the behaviour of the coronal plasma during EUV transition region explosive events detected in N V 1238.8 Å. None of the events observed in N V shows any detectable signature in the Mg X line profile or in its integrated intensity. The analysis of 1996 observations obtained simultaneously in N V 1238.8 Å and S II 1253.8 Å (3.5x 104 K) shows, instead, a weak but clear presence of enhanced wings in the S II line profile during a series of events observed in N V. These results suggest that EUV explosive events are not directly relevant in heating the corona and are characteristic of structures not obviously connected with the upper corona. The evidence of a chromospheric response suggests that, contrary to some previous suggestions, explosive events have a chromospheric origin. Title: Combined space and ground based observations of a C-1 flare Authors: Teriaca, L.; Falchi, A.; Cauzzi, G.; Falciani, R.; Smaldone, L. A.; Andretta, V. Bibcode: 2002ESASP.508..457T Altcode: 2002soho...11..457T We present temporally and spatially resolved space and ground based observations of a C1 flare. Ground based spectroheliograms were acquired at the Dunn Solar Tower of NSO/Sacramento Peak in several chromospheric lines. Simultaneously, the Coronal Diagnostic Spectrograph (CDS) aboard SoHO was used to obtrain rasters of the same active region in transiton region (TR) and coronal lines. This unique dataset provides us, for the first time, with spatially resolved observations of velocity fields during the impulsive phase of the flare, from the chromosphere up to the TR and the corona. At the time of the emission peak, a large area of the flaring kernel observed in TR lines is characterized by upward velocities. A ~6"×6" kernel displays upflows velocity above 80 km s-1. In this same area we found, in data obtained about 3 minutes later, chromospheric downflows of 10 - 20 km s-1. This is the first time that opposite directed flows at different atmospheric levels are observed in the same spatial location during a flare. Title: The fall 2001 polar SOHO-Ulysses quadrature campaign: preliminary results Authors: Aznar Cuadrado, R.; Poletto, G.; Teriaca, L.; Suess, S. T. Bibcode: 2002ESASP.508..481A Altcode: 2002soho...11..481A We present here UVCS observations of a polar coronal hole, acquired during the October/November 2001 SOHO-Sun-Ulysses quadrature. SOHO-Ulysses quadratures occur when the SOHO-Sun-Ulysses included angle is 90° and offer the unique opportunity of comparing the properties of plasma parcels, observed by SOHO in the corona, with properties of the same parcels, measured in situ, in due time, by Ulysses. The October/November 2001 quadrature occurred at a time when Ulysses was at ≍2.2 A.U., at a northern heliographic latitude of ≍80°, off the West limb of the Sun. Observations were taken from October 29 to November 12, 2001, with a ≍3 days data gap, after the eruption of CMEs and the emission of highly energetic particles, on 3-4 November. The UVCS slit was set normal to the solar radius, with the radial to Ulysses going through its zero position. At the time of the campaign, the radial to Ulysses crossed a polar coronal hole. Although its shape was changing, Ulysses was permanently located in a high speed region where CMEs signature can be recognized. Observations in hydrogen Lyman-α and in the 1032 and 1037 Å O VI doublet lines have been made at 1.6 and 2 Rsolar. Line intensities are compared with intensities typically found, at the same altitudes, in polar coronal holes at minimum solar activity and in equatorial holes. The temporal profile of the O VI doublet line ratio and of the O VI line widths, at the position where the radial to Ulysses traverses the solar corona, are shown and a tentative interpreation of the data is outlined. Title: Dynamics and Diagnostics of Explosive Events and Blinkers Authors: Madjarska, M. S.; Doyle, J. G.; Teriaca, L. Bibcode: 2002mwoc.conf...69M Altcode: The knowledge of the main physical parameters of UV explosive events and blinkers, such as density and temperature, is of great importance for the better understanding of the true nature of these transient events. In this context, density and temperature diagnostics based on lines belonging to O iv 1400Å and O iii multiplets is presented for both kind of events. The dynamics of the solar transient phenomena is revealed through their temporal and spatial evolution as observed in spectral lines covering a wide temperature range. The results are obtained using SUMER, CDS, MDI and EIT aboard SoHO, TRACE and Big Bear Solar Observatory observations and are aimed to give more information about the main properties of these phenomena. The events are also studied in connection with the evolution of the underlying magnetic field, searching for observational evidences of their further propagation higher in the solar corona. Title: Radial velocities and orbital solution of the active binary star FG Ursae Majoris Authors: Marino, G.; Catalano, S.; Frasca, A.; Marilli, E.; Teriaca, L. Bibcode: 2002IBVS.5227....1M Altcode: The orbital parameters of the single-lined active binary FG UMa are derived, for the first time, by analyzing medium-resolution spectra collected at Catania Astrophysical Observatory from 1997 till 2000. Radial velocities were measured by using the cross correlation technique. Title: Oxygen abundance in polar coronal holes Authors: Teriaca, L.; Poletto, G.; Falchi, A.; Doyle, J. G. Bibcode: 2001AIPC..598...65T Altcode: 2001sgc..conf...65T Fast solar wind is known to emanate from polar coronal holes. However, only recently attention has been given to the problem of where, within coronal holes, fast wind originates. Information on whether the fast solar wind originates from plumes or interplume regions may be obtained by comparing the elemental abundances in these regions with those characterizing the fast wind. Here we present a first attempt to determine the oxygen abundance in the interplume regions by using spectra taken at times of minimum in the solar cycle (when it is easier to identify these structures) by the SUMER spectrograph aboard SoHO. To this end, we analyze spectra taken in 1996 in polar regions, at altitudes ranging between 1.05 and 1.3 Rsolar, finding a value >=8.5 for the oxygen abundance in the interplume regions. From the analysis of the O VI 1032 to 1037 line intensity ratio we also find no evidence of outflow velocities below 1.2 solar radii in interplume regions, while there are indications that outflow motions start to be significant above 1.5 solar radii. The method used and the assumptions made are discussed in light of the derived values. Our values are compared with previous determinations in the corona and solar wind. . Title: Measuring Solar Abundances Authors: von Steiger, R.; Vial, J. -C.; Bochsler, P.; Chaussidon, M.; Cohen, C. M. S.; Fleck, B.; Heber, V. S.; Holweger, H.; Issautier, K.; Lazarus, A. J.; Ogilvie, K. W.; Paquette, J. A.; Reisenfeld, D. B.; Teriaca, L.; Wilhelm, K.; Yusainee, S.; Laming, J. M.; Wiens, R. C. Bibcode: 2001AIPC..598...13V Altcode: 2001sgc..conf...13V This is the rapporteur paper of Working Group 2 on Measuring Solar Abundances. The working group presented and discussed the different observations and methods for obtaining the elemental and isotopic composition of the Sun, and critically reviewed their results and the accuracies thereof. Furthermore, a few important yet unanswered questions were identified, and the potential of future missions to provide answers was assessed. . Title: Coronal and solar wind elemental abundances Authors: Raymond, J. C.; Mazur, J. E.; Allegrini, F.; Antonucci, E.; Del Zanna, G.; Giordano, S.; Ho, G.; Ko, Y. -K.; Landi, E.; Lazarus, A.; Parenti, S.; Poletto, G.; Reinard, A.; Rodriguez-Pacheco, J.; Teriaca, L.; Wurz, P.; Zangrilli, L. Bibcode: 2001AIPC..598...49R Altcode: 2001sgc..conf...49R Coronal elemental abundances, as compared with abundances in the solar wind and solar energetic particles, provide the means for connecting solar wind gas with its coronal source. Comparison of coronal abundances with photospheric values shows fractionation with the ionization potential of the atom, providing important, though not yet fully understood, information about the exchange of material between corona and chromosphere. Fractionation due to gravitational settling provides clues about flows within the corona. In this paper, we discuss the uncertainties of abundance determinations with spectroscopic techniques and in situ measurements, we survey the ranges of abundance variations in both the corona and solar wind, and we discuss the progress in correlating solar wind features with their coronal sources. . Title: Electron density variations during ultraviolet transient events Authors: Teriaca, L.; Madjarska, M. S.; Doyle, J. G. Bibcode: 2001SoPh..200...91T Altcode: % High-resolution temporal observations performed with the SUMER spectrometer on SOHO provide an opportunity to investigate the electron density variations in the `quiet-Sun' solar transition region due to UV transient events. Two datasets obtained in the density sensitive lines belonging to the O iv 1400 Å multiplet were searched for such events, leading to the identification of two explosive events, on 10 July 1996 and 31 May 1997. In both cases, the O iv 1401.16/1404.81 density-sensitive line intensity ratio shows a clear variation, corresponding to enhancements in the electron density by factors of ∼3. This is fully consistent with recent 2.5D MHD simulations. The 10 July 1996 dataset also provided us with the opportunity to monitor the behavior of the electron density through an UV blinker. Despite an increase of a factor of two in the line intensities, no variation of the electron density was found. This suggests that the intensity enhancement is due to an increase in the filling factor. Title: Numerical Modeling of the Transition Region Dynamics Authors: Teriaca, L.; Doyle, J. G. Bibcode: 2001ASSL..259..307T Altcode: 2001dysu.conf..307T We explore the idea that the occurrence of nano-flares in a magnetic loop around the O VI formation temperature could explain the observed red-shift of mid-low transition region lines as well as the blue-shift observed in low coronal lines (T > 6 times 105 K). Observations are compared to numerical simulations of the response of the solar atmosphere to an energy perturbation of 4 times 1024 ergs representing an energy release during magnetic reconnection in a 1-D semi-circular flux tube. The temporal evolution of the thermodynamic state of the loop is finally converted into C III 977, C IV 1548, O V 630, O VI 1032, Ne VII 465 and Ne VIII 770 line profiles in non-equilibrium ionization. Performing an integration over the entire period of simulation, redshifts of 8.5, 6.1 and 1.7 km s-1, are found in C III, C IV, and O V while blue-shifts of -1.8, -3.9 and -10.7 km s-1 were derived for O VI, Ne VII and Ne VIII respectively, in good agreement with observations. Title: Electron Density Enhancement During an UV Explosive Event Authors: Madjarska, M. S.; Doyle, J. G.; Teriaca, L. Bibcode: 2001IAUS..203..407M Altcode: High resolution temporal observations performed with the SUMER spectrometer on SOHO provide us the opportunity to investigate the electron density variations in the solar mid transition region due to explosive event-like phenomena. The O IV 1401.16/1404.81 density sensitive line intensity ratio shows a clear increase during a strong explosive event, corresponding to an electron density enhancement of a factor of ~ 3.5 respect to pre-event values. This is consistent with recent MHD simulations (2.5 D) carried out by Karpen et al. (1998). Karpen J. T., Antiochos S. K., DeVore C. R. and Golub L., 1998, ApJ 495, 491. Title: Structure and dynamics of the solar outer atmosphere as inferred from EUV observations Authors: Teriaca, Luca Nunzio Bibcode: 2001PhDT.........2T Altcode: EUV observations obtained with the SUMER/SOHO are analysed, obtaining information about the density, temperature and velocity fields characterizing the solar plasma. We measure the amount of line shift and width as a function of temperature for several transition region lines, on both quiet Sun and, an active region. A reversal from redshift to blueshift happens at temperatures above 5 10 5 K. We explore the idea that the occurrence of nano-flares in a magnetic loop could explain the observed line shift behaviour. Observations are compared to numerical simulations of the response of the solar atmosphere to an energy perturbation. The temporal evolution of the thermodynamic state of the loop model is converted into line profiles in non-equilibrium ionization, finding good agreement with observations. The center-to-limb variation of the non-thermal velocity is particularly important in discriminating the heating mechanism. Full disk images in He I, C IV and Ne VIII are, hence, used to investigate whether there exists a center-to-limb variation in the line width, finding that the unresolved mass motions in the solar atmosphere are prevalently isotropic. The effects of energetic phenomena on the solar plasma have also been studied through high-resolution temporal observations of the electron density behaviour during UV transient events, finding enhancements of a factor of ~3 associated with explosive events. We also provide electron density measurements in network and internetwork regions and during an UV blinker. The measurement of line widths can provide information concerning velocity fluctuations associated with MHD waves in the corona. The velocity fields in plume and inter-plume regions were investigated in detail, showing that the darker inter-plume lanes (believed to be the locations where the fast solar wind originates) are characterized by broader line profiles. The variation of the line width and electron density as a function of height above two coronal holes was, hence, obtained in the inter-plume. We find that the non-thermal velocity is inversely proportional to the quadratic root of the electron density, in excellent agreement with that predicted for undamped radially propagating Alfvén waves. We show that the energy flux associated with these hydromagnetic waves is sufficient to drive the high speed solar wind streams. Title: SUMER Observations of the Solar Transition Region: Spatial and Temporal Behaviour Authors: Teriaca, L.; Doyle, J. G.; Banerjee, D. Bibcode: 2001IAUS..203..425T Altcode: In this paper we examine the spatial and temporal behaviour of the quiet Sun transition region using high resolution SUMER observations in O VI 1032. The observations are devoted to the study of the variability in the transition region and consists of four raster scans of the same area followed by a long series of spectra taken in the same position with high temporal cadence. A detailed study of the raster images allows us to differentiate the network and internetwork through Doppler shift and line width measurements. We have also identified several explosive-events like phenomena toghether with an UV bright point. We also show evidence for a possible formation of a shock front after one partcular bright point appearence. The oscillatory nature of the transition region is finally investigated using the wavelet analysis and particular attention has been paid to the effect due to the occurrence of explosive events. Title: The magnetic activity cycle of II Pegasi: results from twenty-five years of wide-band photometry Authors: Rodonò, M.; Messina, S.; Lanza, A. F.; Cutispoto, G.; Teriaca, L. Bibcode: 2000A&A...358..624R Altcode: We present an analysis of a sequence of light curves of the RS CVn-type binary II Pegasi extending from 1974 to 1998. The distribution of the spotted area versus longitude is derived by Maximum Entropy and Tikhonov regularized maps, assuming a constant spot temperature (Lanza et al. 1998a). The spot pattern on the active K2 IV star can be subdivided into a component uniformly distributed in longitude and a second unevenly distributed component, which is responsible for the observed photometric modulation. The uniformly distributed component appears to be possibly modulated with an activity cycle of ~ 13.5 yr. The unevenly distributed component is mainly concentrated around three major active longitudes. The spot activity appears practically permanent at one longitude, but the spot area changes with a cycle of ~ 9.5 yr. On the contrary, the spot activity is discontinuous at the other two longitudes, and it switches back and forth between them with a cycle of ~ 6.8 yr. However, before each switching is completed, a transition phase of ~ 1.05 yr, during which both longitudes are active, occurs. After this transient phase, spot activity remains localized at one of the two longitudes for ~ 4.7 yr untill another switching event occurs, which re-establishes spot activity at the other longitude. The longitude separation between the permanent and the switching active longitudes is closest during the switching phases and it varies along the ~ 6.8 yr cycle. Different time scales characterize the activity at the permanent longitude and at the switching longitudes: a period of ~ 9.5 yr is related to the activity cycle at the permanent longitude, and a period of ~ 4.3 yr characterizes the spot life time at the switching longitudes in between switching events. The photometric period of the active star changes from season to season with a relative amplitude of 1.5% and a period of ~ 4.7 yr. Such a variation of the photometric period may be likely associated with the phase shift of the light curves produced by the switching of spot activity from one active longitude to the other. The permanently active longitude shows a steady migration towards decreasing orbital phases, with an oscillating migration rate along the 9.5 yr cycle period and nearly in phase with the variation of its spotted area. The amplitude of the differential rotation derived from such a behaviour is of the order of ~ 0.023%, about one order of magnitude smaller than estimated by Henry et al. (1995). The other two active longitudes migrates also towards decreasing orbital phase, but at a discontinuous rate. There appears to be no correlation between the location of the active longitudes with respect to the line joining the two components of the system and their activity level. Title: Polar Plumes and Inter-plume regions as observed by SUMER on SOHO Authors: Banerjee, D.; Teriaca, L.; Doyle, J. G.; Lemaire, P. Bibcode: 2000SoPh..194...43B Altcode: We present observations of O vi 1032 Å line profiles obtained with the SUMER instrument on SOHO extending from the solar disk to 1.5 R⊙ above the limb in the north polar coronal hole. Variations of the intensity and linewidth in the polar plume and inter-plume regions are investigated. We find an anti-correlation between the intensity and the linewidth in the plume and inter-plume regions with detailed plume structures been seen out to 1.5 R⊙. Possible implications regarding the magnetic topologies of these two regions and related heating mechanisms are discussed. The O vi linewidth measurements are combined with UVCS output to provide an overview of its variations with height extending up to 3.5 R⊙. We find a linear increase of the linewidth from 1 to 1.2 R⊙, then a plateau followed by a sharp increase around 1.5 R⊙. Title: Solar transition region line broadening: Limb to limb measurements Authors: Doyle, J. G.; Teriaca, L.; Banerjee, D. Bibcode: 2000A&A...356..335D Altcode: Full disk images from SUMER/SoHO taken in He I, C IV and Ne VIII are used to investigate whether there exists a center-to-limb variation in the line width. Both C IV and He I show such a variation but the higher temperature Ne VIII line is relatively constant. For C IV, this corresponds to ~ 3 km s-1 difference while He I is significantly larger particularly at the limb. This work may suggest that the non-thermal motions are slightly non-isotropic in the transition region and upper chromosphere, with the horizontal unresolved motions exceeding those in the vertical plane however a more probable explanation is that the lines are broadened due to opacity effects. The more slower variation in the C IV 1548 Ä line width could be explained by increasing the opacity from zero at disk center to ~ 1 at the limb. For He I the opacity is significantly grater than unity at the limb. This therefore implying all mass motions in the chromosphere, transition region and corona are isotropic. Title: New Insight in Transition Region Dynamics as Derived from SUMER Observations and Numerical Modelling Authors: Teriaca, L.; Doyle, J. G.; Erdélyi, R.; Sarro, L. M.; Banerjee, D. Bibcode: 1999ESASP.448..379T Altcode: 1999ESPM....9..379T; 1999mfsp.conf..379T No abstract at ADS Title: New insight into transition region dynamics via SUMER observations and numerical modelling Authors: Teriaca, L.; Doyle, J. G.; Erdélyi, R.; Sarro, L. M. Bibcode: 1999A&A...352L..99T Altcode: We explore the idea that the occurrence of nano-flares in a magnetic loop around the O vi formation temperature could explain the observed red-shift of mid-low transition region lines as well as the blue-shift observed in low coronal lines (T > 6x 105\ K). Observations are compared to numerical simulations of the response of the solar atmosphere to an energy perturbation of 4x 1024 ergs representing an energy release during magnetic reconnection in a 1-D semi-circular flux tube. The temporal evolution of the thermodynamic state of the loop is converted into C iv 1548, O vi 1032 and Ne viii 770 line profiles in non-equilibrium ionization. Performing an integration over the entire period of simulations, a redshift of ~ 6\ km\ s-1 is found in C iv, while a blue-shift of ~ 2\ km\ s-1 and ~ 10\ km\ s-1 were derived for O vi and Ne viii, respectively, in reasonable agreement with observations. Title: SUMER Observations of Line Shifts in the Quiet Sun and in an Active Region Authors: Teriaca, L.; Banerjee, D.; Doyle, J. G.; Erdély, R. Bibcode: 1999ESASP.446..645T Altcode: 1999soho....8..645T The UV spectral lines formed at transition region temperatures in the solar atmosphere, shows a prevailing redshifted emission. Using the Solar Ultraviolet Measurements of Emitted Radiation spectrometer flown on the Solar and Heliospheric Observatory spacecraft, we measure the amount of line shift as a function of the temperature for several spectral lines formed in the range between 104 and 106 K. We analyze spectrograms relative to the quiet Sun and to the active region NOAA 7946. The velocities derived are increasing from a redshift of ~ 0 km/s at ~ 20000 K to 10 km/s at 1.9x105 K for the quiet Sun, and to ~ 15 km/s at 105 K for the active region. At higher temperature an opposite behaviour is observed. In the quiet Sun a blueshift of ~ -2 km/s is observed at the Ne viii formation temperature (6x105 K), while in the active region, a blue-shifted value around -8 km/s is observed for the same spectral line. By 106 K the blueshift is ~ -10 km/s in the active region as measured by Fe xii 1242. Title: Coronal Hole Diagnostics out to 8 solar radii Authors: Doyle, J. G.; Teriaca, L.; Banerjee, D.; Fludra, A. Bibcode: 1999ESASP.446..281D Altcode: 1999soho....8..281D The line width measurements (from Si VIII) and Ne estimates (from Si VIII and Si IX) based on SUMER and CDS observations are combined with LASCO and UVCS output to provide an overview of its variations with height above a polar coronal hole. From the combined dataset we find a radial dependence of the electron density, in the range 1-2 solar radii as r-8, from 2 to 4 solar radii as r-4 and then as r-2. Combining the Si VIII half width at 1/e of the peak intensity with the UVCS O VI half width, we find a small increase of the half width from 1 to 1.2 solar radii, then a plateau until 1.5 solar radii, thereafter a sharp increase until 2 solar radii, finally a more gradual increase reaching 550 km/s at 3.5 solar radii. Our data suggests that the MHD waves responsible for the excess line broadening tends to become non-linear as it reaches 1.2 solar radii. Title: SUMER observations of Doppler shift in the quiet Sun and in an active region Authors: Teriaca, L.; Banerjee, D.; Doyle, J. G. Bibcode: 1999A&A...349..636T Altcode: The UV spectral lines formed at transition region temperatures in the solar atmosphere, show a prevailing redshifted emission. Using the Solar Ultraviolet Measurements of Emitted Radiation spectrometer flown on the Solar and Heliospheric Observatory spacecraft, we measure the amount of line shift as a function of the temperature for several spectral lines formed in the range between 10(4) and 10(6) \ K. We analyze spectrograms relative to the quiet Sun and to the active region NOAA\ 7946. The velocities derived are increasing from a redshift of ~ \ 0 \ km ; s(-1) at ~ 20000\ K to 10\ km ; s(-1) at 1.9\ 10(5) \ K for the quiet Sun, and to ~ 15 \ km ; s(-1) at 10(5) \ K for the active region. At higher temperature an opposite behaviour is observed. In the quiet Sun a blueshift of ~ \ -2 \ km ; s(-1) is observed at the Ne viii formation temperature (6.3\ 10(5) \ K), while in the active region, a blue-shifted value around -8\ km ; s(-1) is observed for the same spectral line. The finding of blueshift in Ne viii is due to the adoption of a new rest wavelength of 770.428 Ä. By 10(6) \ K the blueshift is ~ \ -10 \ km ; s(-1) in the active region as measured by Fe xii 1242. Title: Coronal hole diagnostics out to 8Rsun Authors: Doyle, J. G.; Teriaca, L.; Banerjee, D. Bibcode: 1999A&A...349..956D Altcode: The Si viii line width measurements and N_e estimates based on SUMER observations are combined with LASCO and UVCS output to provide an overview of its variations with height above a polar coronal hole. From the combined dataset we find a radial dependence of the electron density, in the range 1-2 Rsun as r(-8) , from 2 to 4 Rsun as r(-4) and then as r(-2) . Combining the Si viii half width at 1/e of the peak intensity with the UVCS O vi half width, we find a small increase of the half width from 1 to 1.2 Rsun, then a plateau until 1.5 Rsun, thereafter a sharp increase until 2 Rsun, finally a more gradual increase reaching 550 km s(-1) at 3.5 Rsun. Our data suggests that the MHD waves responsible for the excess line broadening tends to become non-linear as it reaches 1.2 Rsun. Title: Alfvén waves in the solar polar coronal holes Authors: Banerjee, D.; Teriaca, L.; Doyle, J. G.; Wilhelm, K. Bibcode: 1999AIPC..471..289B Altcode: 1999sowi.conf..289B We study the variation of the line width and electron density as a function of height above two coronal holes from forbidden spectral lines of Si VIII. The spectra were obtained with the Solar Ultraviolet Measurements of Emitted Radiation spectrometer flown on the Solar and Heliospheric Observatory spacecraft. The observations concentrate on the dark regions outside the plumes, which are believed to be the location, where the fast solar wind originates. The line width data show that the non-thermal line-of-sight velocity increases from 20 km s-1 at 27 arc sec above the limb to 37 km s-1 some 370 arc sec (i.e. ~1.38 Rsolar) above the limb. The electron density shows a decrease from 3.5 108 cm-3 to 1.6 107 cm-3 over the same distance. This data implies that the non-thermal velocity is inversely proportional to the quadratic root of the electron density in the range 1-1.2 Rsolar, in excellent agreement with that predicted for undamped radially propagating Alfvén waves. Beyond 1.2 Rsolar our data suggests an effective breakdown of linear theory for the propagation of Alfvén waves. Title: Line Width Variations above a Coronal Hole: Implications for Heating Authors: Doyle, J. G.; Teriaca, L.; Banerjee, D. Bibcode: 1999ASPC..158..366D Altcode: 1999ssa..conf..366D No abstract at ADS Title: SUMER Observations of Doppler Shifts in the Quiet Sun and an Active Region Authors: Teriaca, L.; Doyle, J. G.; Banerjee, D. Bibcode: 1999ASPC..158..362T Altcode: 1999ssa..conf..362T No abstract at ADS Title: Light Curve Variation and Flare Eruption in the Sun and Stars Authors: Teriaca, L.; Catalano, S. Bibcode: 1999ASPC..158..243T Altcode: 1999ssa..conf..243T No abstract at ADS Title: Broadening of SI VIII lines observed in the solar polar coronal holes Authors: Banerjee, D.; Teriaca, L.; Doyle, J. G.; Wilhelm, K. Bibcode: 1998A&A...339..208B Altcode: We study the variation of the line width and electron density as a function of height above two coronal holes from forbidden spectral lines of Si viii. The spectra were obtained with the Solar Ultraviolet Measurements of Emitted Radiation spectrometer flown on the Solar and Heliospheric Observatory spacecraft. The observations concentrate on the dark regions outside the plumes, which are believed to be the locations, where the fast solar wind originates. The line width data show that the non-thermal line-of-sight velocity increases from 27 {km s}(-1) at 27 arc sec above the limb to 46 {km s}(-1) some 250 arc sec ({i.e. } ~ 180,000 km) above the limb. The electron density shows a decrease from 1.1 10(8) {cm}(-3) to 1.6 10(7) {cm}(-3) over the same distance. This data implies that the non-thermal velocity is inversely proportional to the quadratic root of the electron density, in excellent agreement with that predicted for undamped radially propagating Alfven waves. We show that the energy flux associated with these hydromagnetic waves is sufficient to drive the high speed solar wind streams. Title: Line Width Variations in the Solar Polar Coronal Holes Authors: Teriaca, L.; Banerjee, D.; Doyle, J. G. Bibcode: 1998ESASP.417..329T Altcode: 1998cesh.conf..329T No abstract at ADS Title: Stellar Flare and Light Curve Variations in Active Binary Systems Authors: Teriaca, L. Bibcode: 1997PhDT........20T Altcode: No abstract at ADS