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Localised transient EUV brightenings, sometimes named `campfires', occur throughout the quiet-Sun. However, there are still many open questions about such events, in particular regarding their temperature range and dynamics. In this article, we aim to determine whether any transition region response can be detected for small-scale EUV brightenings and, if so, to identify whether the measured spectra correspond to any previously reported bursts in the transition region, such as Explosive Events (EEs). EUV brightenings were detected in a ~29.4 minute dataset sampled by Solar Orbiter's Extreme Ultraviolet Imager on 8 March 2022 using an automated detection algorithm. Any potential transition region response was inferred through analysis of imaging and spectral data sampled through coordinated observations conducted by the Interface Region Imaging Spectrograph (IRIS). EUV brightenings display a range of responses in IRIS slit-jaw imager (SJI) data. Some events have clear signatures in the Mg II and Si IV SJI filters, whilst others have no discernible counterpart. Both extended and more complex EUV brightenings are found to, sometimes, have responses in IRIS SJI data. Examples of EUI intensities peaking before, during, and after their IRIS counterparts were found in lightcurves constructed co-spatial to EUV brightenings. Importantly, therefore, it is likely that not all EUV brightenings are driven in the same way, with some seemingly being magnetic reconnection driven and others not. A single EUV brightening occurred co-spatial to the IRIS slit, with its spectra matching the properties of EEs. EUV brightenings is a term used to describe a range of small-scale event in the solar corona. The physics responsible for all EUV brightenings is likely not the same and, therefore, more research is required to assess their importance towards global questions in the field, such as coronal heating., Comment: Accepted to A&A, 9 figures

Coronal rain is the most dramatic cooling phenomenon of the solar corona and an essential diagnostic tool for the coronal heating properties. A puzzling feature of the solar corona, besides the heating, is its EUV filamentary structure and variability. We aim to identify observable features of the TNE-TI scenario underlying coronal rain at small and large spatial scales, to understand the role it plays in the solar corona. We use EUV datasets at unprecedented spatial resolution of ~240 km from EUI/HRIEUV and SPICE of Solar Orbiter from the spring 2022 perihelion. EUV absorption features produced by coronal rain are detected at scales as small as 260 km. As the rain falls, heating and compression is produced immediately downstream, leading to a small EUV brightening accompanying the fall and producing a "fireball" phenomenon. Just prior to impact, a flash-like EUV brightening downstream of the rain, lasting a few minutes is observed for the fastest events. For the first time, we detect the atmospheric response to the rain's impact on the chromosphere and consists of upward propagating rebound shocks and flows partly reheating the loop. The observed widths of the rain clumps are 500 +- 200 km. They exhibit a broad velocity distribution of 10 - 150 km s^-1, peaking below 50 km s^-1. Coronal strands of similar widths are observed along the same loops co-spatial with cool filamentary structure, which we interpret as the CCTR. Matching with the expected cooling, prior to the rain appearance sequential loop brightenings are detected in gradually cooler lines from corona to chromospheric temperatures. Despite the large rain showers, most cannot be detected in AIA 171 in quadrature, indicating that LOS effects play a major role in coronal rain visibility. Still, AIA 304 and SPICE observations reveal that only a small fraction of the rain can be captured by HRIEUV., Comment: Astronomy & Astrophysics; 32 Pages, 24 Main Figures, Appendix

Full list of authors: Noda, C. Quintero; Schlichenmaier, R.; Bellot Rubio, L. R.; Lofdahl, M. G.; Khomenko, E.; Leenaarts, J.; Kuckein, C.; Gonzalez Manrique, S. J.; Gunar, S.; Nelson, C. J.; Rodriguez, J. de la Cruz; Tziotziou, K.; Tsiropoula, G.; Aulanier, G.; Aboudarham, J.; Allegri, D.; Alsina Ballester, E.; Amans, J. P.; Asensio Ramos, A.; Bailen, F. J.; Balaguer, M.; Baldini, V; Balthasar, H.; Barata, T.; Barczynski, K.; Barreto Cabrera, M.; Baur, A.; Bechet, C.; Beck, C.; Belio-Asin, M.; Bello-Gonzalez, N.; Belluzzi, L.; Bentley, R. D.; Berdyugina, S., V; Berghmans, D.; Berlicki, A.; Berrilli, F.; Berkefeld, T.; Bettonvil, F.; Bianda, M.; Bienes Perez, J.; Bonaque-Gonzalez, S.; Brajsa, R.; Bommier, V; Bourdin, P-A; BurgosMartin, J.; Calchetti, D.; Calcines, A.; Calvo Tovar, J.; Campbell, R. J.; Carballo-Martin, Y.; Carbone, V; Carlin, E. S.; Carlsson, M.; Castro Lopez, J.; Cavaller, L.; Cavallini, F.; Cauzzi, G.; Cecconi, M.; Chulani, H. M.; Cirami, R.; Consolini, G.; Coretti, I; Cosentino, R.; Cozar-Castellano, J.; Dalmasse, K.; Danilovic, S.; Ovelar, M. De Juan; Del Moro, D.; del Pino Aleman, T.; del Toro Iniesta, J. C.; Denker, C.; Dhara, S. K.; Di Marcantonio, P.; Baso, C. J. Diaz; Diercke, A.; Dineva, E.; Diaz-Garcia, J. J.; Doerr, H-P; Doyle, G.; Erdelyi, R.; Ermolli, I; Escobar Rodriguez, A.; Esteban Pozuelo, S.; Faurobert, M.; Felipe, T.; Feller, A.; Feijoo Amoedo, N.; Femenia Castella, B.; Fernandes, J.; Ferro Rodriguez, I; Figueroa, I; Fletcher, L.; Franco Ordovas, A.; Gafeira, R.; Gardenghi, R.; Gelly, B.; Giorgi, F.; Gisler, D.; Giovannelli, L.; Gonzalez, F.; Gonzalez, J. B.; Gonzalez-Cava, J. M.; Gonzalez Garcia, M.; Gomory, P.; Gracia, F.; Grauf, B.; Greco, V; Grivel, C.; Guerreiro, N.; Guglielmino, S. L.; Hammerschlag, R.; Hanslmeier, A.; Hansteen, V; Heinzel, P.; Hernandez-Delgado, A.; Hernandez Suarez, E.; Hidalgo, S. L.; Hill, F.; Hizberger, J.; Hofmeister, S.; Jagers, A.; Janett, G.; Jarolim, R.; Jess, D.; Jimenez Mejias, D.; Jolissaint, L.; Kamlah, R.; Kapitan, J.; Kasparova, J.; Keller, C. U.; Kentischer, T.; Kiselman, D.; Kleint, L.; Klvana, M.; Kontogiannis, I; Krishnappa, N.; Labrosse, N.; Lagg, A.; Degl'Innocenti, E. Landi; Langlois, M.; Lafon, M.; Laforgue, D.; Le Men, C.; Lepori, B.; Lepreti, F.; Lindberg, B.; Lilje, P. B.; Ariste, A. Lopez; Lopez Fernandez, V. A.; Lopez Jimenez, A. C.; Lopez Lopez, R.; Sainz, R. Manso; Marassi, A.; Marco de la Rosa, J.; Marino, J.; Marrero, J.; Martin, A.; Martin Galvez, A.; Martin Hernando, Y.; Masciadri, E.; MartinezGonzalez, M.; Matta-Gomez, A.; Mato, A.; Mathioudakis, M.; Matthews, S.; Mein, P.; Merlos Garcia, F.; Moity, J.; Montilla, I; Molinaro, M.; Molodij, G.; Montoya, L. M.; Munari, M.; Murabito, M.; Nunez Cagigal, M.; Oliviero, M.; Orozco Suarez, D.; Ortiz, A.; Padilla-Hernandez, C.; Paez Mana, E.; Paletou, F.; Pancorbo, J.; Pastor Canedo, A.; Yabar, A. Pastor; Peat, A. W.; Pedichini, F.; Peixinho, N.; Penate, J.; Perez de Taoro, A.; Peter, H.; Petrovay, K.; Piazzesi, R.; Pietropaolo, E.; Pleier, O.; Poedts, S.; Potzi, W.; Podladchikova, T.; Prieto, G.; Quintero Nehrkorn, J.; Ramelli, R.; Ramos Sapena, Y.; Rasilla, J. L.; Reardon, K.; Rebolo, R.; Regalado Olivares, S.; Reyes Garcia-Talavera, M.; Riethmuller, T. L.; Rimmele, T.; Rodriguez Delgado, H.; Rodriguez Gonzalez, N.; Rodriguez-Losada, J. A.; Rodriguez Ramos, L. F.; Romano, P.; Roth, M.; vander Voort, L. Rouppe; Rudawy, P.; Ruiz de Galarreta, C.; Rybak, J.; Salvade, A.; Sanchez-Capuchino, J.; Sanchez Rodriguez, M. L.; Sangiorgi, M.; Sayede, F.; Scharmer, G.; Scheiffelen, T.; Schmidt, W.; Schmieder, B.; Scire, C.; Scuderi, S.; Siegel, B.; Sigwarth, M.; Simoes, P. J. A.; Snik, F.; Sliepen, G.; Sobotka, M.; Socas-Navarro, H.; Sola La Serna, P.; Solanki, S. K.; Soler Trujillo, M.; Soltau, D.; Sordini, A.; Sosa Mendez, A.; Stangalini, M.; Steiner, O.; Stenflo, J. O.; Stepan, J.; Strassmeier, K. G.; Sudar, D.; Suematsu, Y.; Sutterlin, P.; Tallon, M.; Temmer, M.; Tenegi, F.; Tritschler, A.; Trujillo Bueno, J.; Turchi, A.; Utz, D.; van Harten, G.; VanNoort, M.; van Werkhoven, T.; Vansintjan, R.; Vaz Cedillo, J. J.; Vega Reyes, N.; Verma, M.; Veronig, A. M.; Viavattene, G.; Vitas, N.; Vogler, A.; von der Luhe, O.; Volkmer, R.; Waldmann, T. A.; Walton, D.; Wisniewska, A.; Zeman, J.; Zeuner, F.; Zhang, L. Q.; Zuccarello, F.; Collados, M.--This is an Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited., The European Solar Telescope (EST) is a project aimed at studying the magnetic connectivity of the solar atmosphere, from the deep photosphere to the upper chromosphere. Its design combines the knowledge and expertise gathered by the European solar physics community during the construction and operation of state-of-the-art solar telescopes operating in visible and near-infrared wavelengths: the Swedish 1m Solar Telescope, the German Vacuum Tower Telescope and GREGOR, the French Télescope Héliographique pour l’Étude du Magnétisme et des Instabilités Solaires, and the Dutch Open Telescope. With its 4.2 m primary mirror and an open configuration, EST will become the most powerful European ground-based facility to study the Sun in the coming decades in the visible and near-infrared bands. EST uses the most innovative technological advances: the first adaptive secondary mirror ever used in a solar telescope, a complex multi-conjugate adaptive optics with deformable mirrors that form part of the optical design in a natural way, a polarimetrically compensated telescope design that eliminates the complex temporal variation and wavelength dependence of the telescope Mueller matrix, and an instrument suite containing several (etalon-based) tunable imaging spectropolarimeters and several integral field unit spectropolarimeters. This publication summarises some fundamental science questions that can be addressed with the telescope, together with a complete description of its major subsystems. © C. Q. Noda et al. 2022., C.Q.N. was supported by the EST Project Office, funded by the Canary Islands Government (file SD 17/01) under a direct grant awarded to the IAC on ground of public interest. This project has received funding from the European Union’s Horizon 2020 Research and Innovation programme under Grant Agreements No 739500 (PRE-EST) and 653982 (GREST). This project was supported by the European Commission’s FP7 Capacities Programme under Grant Agreements No 212482 (EST Design Study) and No. 312495 (SOLARNET). It was also supported by the European Union’s Horizon 2020 Research and Innovation programme under Grant Agreement No. 824135 (SOLARNET). This work has been partially funded by the Spanish Ministry of Science and Innovation through project RTI2018-096886-B-C51, including a percentage from FEDER funds, and through the Centro de Excelencia Severo Ochoa grant SEV-2017-0709 awarded to the Instituto de Astrofísica de Andalucía in the period 2018-2022. The EST preparatory phase was supported by a grant for research infrastructures of national importance from the Swedish Research Council (registration number 2017-00625). J.J. was supported by the Ministry of Education, Youth and Sports of the Czech Republic through the EST-CZ project (LM2018095). C.K. acknowledges funding received from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 895955. Queen’s University Belfast acknowledges support from the Science and Technology Facilities Council (STFC) under grant No. ST/V003739/1. This work was supported by Fundação para a Ciência e a Tecnologia (FCT) through the research grants [UID/FIS/04434/2019], UIDB/04434/2020, UIDP/04434/2020, UIDB/00611/2020 and UIDP/00611/2020. This work was partly funded by a grant of the Austrian Science Fund (FWF): P 32958-N. J.C.R., C.J.D.B. and A.P.Y. gratefully acknowledge financial support from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (SUNMAG, grant agreement 759548). J.A. was supported by Centre National d’Etudes Spatiales (CNES). G.A., M.C., L.F., V.H., A.O. and L.R.V.V acknowledge support by the Research Council of Norway through its Centres of Excellence scheme, project number 262622. L.B., M.B., R.R. acknowledge State Secretariat for Education, Research, and Innovation (SERI), Canton Ticino and Swiss National Science Foundation (grants 200020_184952, 200021_175997, CRSII5_180238) for the financial support. R. Brajša and D. Sudar acknowledge the support by the Croatian Science Foundation under project 7549 ‘Millimeter and submillimeter observations of the solar chromosphere with ALMA’. The NSO is operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation. The work of A.B. was partially supported by the programme ‘Excellence Initiative – Research University’ for years 2020–2026 for University of Wrocław, project no. BPIDUB.4610.15.2021.KP.B. E.S.C. acknowledges financial support from the Spanish Ministry of Science and Innovation (MICINN) through the Spanish State Research Agency, under Severo Ochoa Centres of Excellence Programme 2020-2023 (CEX2019-000920-S). L.F. and N.L. would like to acknowledge support from UK Research and Innovation Science and Technology Facilities Council grants ST/L006200/1 and ST/T000422/1. J.F. acknowledges visiting facilities at Rosseland Centre for Solar Physics (University of Oslo), in 2019. P. Gömöry, A.K. and J.R. were supported by the Science Grant Agency project VEGA 2/0048/20. I. Kontogiannis is supported by KO 6283/2-1 of the Deutsche Forschungsgemeinschaft (DFG). C.J.N. is thankful to the Science and Technology Facilities Council (STFC), for support received through grant ST/T00021X/1, and ESA, for support as an ESA Research Fellow. K.P. was supported by the Hungarian National Research, Development and Innovation Fund (grants no. NKFI K-128384 and TKP2021-NKTA-64). P.J.A. Simões acknowledges support from CNPq (contract 307612/2019-8). J.T.B. acknowledges the funding received from the European Research Council (ERC) under de European Union’s Horizon 2020 research and innovation programme (ERC Advanced Grant Agreement No. 742265). M.V. is supported by VE 1112/1-1 of the Deutsche Forschungsgemeinschaft (DFG). L.Q.Z. acknowledges that this work was supported by the National Natural Science Foundation of China (Grant No. 11727805, No. 1210030348). F.Z. acknowledges that this work was supported by the Italian MIUR-PRIN grant 2017APKP7T and by the Università degli Studi di Catania (Piano per la Ricerca Università di Catania 2020-2022, Linea di intervento 2).

We report observations of a unique, large prominence eruption that was observed in the He II 304 Å passband of the the Extreme Ultraviolet Imager/Full Sun Imager telescope aboard Solar Orbiter on 15-16 February 2022. Observations from several vantage points (Solar Orbiter, the Solar-Terrestrial Relations Observatory, the Solar and Heliospheric Observatory, and Earth-orbiting satellites) were used to measure the kinematics of the erupting prominence and the associated coronal mass ejection. Three-dimensional reconstruction was used to calculate the deprojected positions and speeds of different parts of the prominence. Observations in several passbands allowed us to analyse the radiative properties of the erupting prominence. The leading parts of the erupting prominence and the leading edge of the corresponding coronal mass ejection propagate at speeds of around 1700 km/s and 2200 km/s, respectively, while the trailing parts of the prominence are significantly slower (around 500 km/s). Parts of the prominence are tracked up to heights of over $6 R_\sun$. The He II emission is probably produced via collisional excitation rather than scattering. Surprisingly, the brightness of a trailing feature increases with height. The reported prominence is the first observed in He II 304 Å emission at such a great height (above 6 $R_\sun$).

Solar eruptions are usually associated with a variety of phenomena occurring in the low corona before, during, and after onset of eruption. Though easily visible in coronagraph observations, so-called stealth coronal mass ejections (CMEs) do not obviously exhibit any of these low-coronal signatures. The presence or absence of distinct low coronal signatures can be linked to different theoretical models to establish the mechanisms by which the eruption is initiated and driven. In this study, 40 CMEs without low coronal signatures, occurring in 2012, are identified. Their observational and kinematic properties are analyzed and compared to those of regular CMEs. Solar eruptions without clear on-disk or low coronal signatures can lead to unexpected space weather impacts, since many early warning signs for significant space weather activity are not present in these events. A better understanding of their initiation mechanism(s) will considerably improve the ability to predict such space weather events., Comment: 42 pages, 10 figures

Study Design. In 100 consecutive patients who underwent surgery because of soft cervical disc herniation, the sagittal and transverse diameters, the area of the bony cervical spinal canal, the sagittal diameter of the hernia, and the minimal bony intervertebral foramen diameter were measured by computed tomography. The data were compared with measurements from a control group of 35 matched healthy individuals. Objectives. To evaluate the relation between the severity of concurrent neurologic symptoms and the sagittal and transverse diameters, the cross-sectional area of the bony spinal canal, the sagittal diameter of the hernia, and diameter of the minimal bony intervertebral foramen in patients with soft cervical disc herniation. Summary of Background Data. Traumatic injury and spondylotic changes have a far greater impact on the spinal cord and nerve roots if the sagittal diameter of the bony cervical spinal canal is small. However, in the case of soft cervical disc herniation, no computer tomographic measurements are available for sagittal and transverse diameters, cross-sectional area of the bony spinal canal, sagittal diameter of the hernia, and diameter of the minimal bony intervertebral foramen in relation to the severity of concurrent neurologic symptoms. Methods. Computed tomography was used to measure sagittal and transverse diameters, cross-sectional area of the bony cervical spinal canal, sagittal diameter of the hernia, and diameter of the minimal bony intervertebral foramen in 100 patients with symptomatic monosegmental cervical soft disc herniation. All patients had undergone an anterior discectomy with removal of the hernia and subsequent interbody fusion using an autologous bone graft taken from the iliac crest. Results. A mean sagittal diameter of the bony cervical spinal canal of 12.9 mm was found, indicating a certain degree of developmental stenosis. Patients with motor disturbances had a significantly smaller sagittal diameter of the bony spinal canal than did patients without motor disturbances. There was a linear correlation between the sagittal diameter of the bony cervical spinal canal and that of the hernia. The sagittal diameter, the area of the bony spinal canal, and diameter of the minimal bony intervertebral foramen were significantly smaller in patients with soft cervical disc herniation than in the control group. Conclusions. Results from this study strongly suggest that the degree and severity of neurologic symptoms accompanying cervical soft disc herniation are inversely related to the sagittal diameter and the area of the bony cervical spinal canal. The latter area is reduced in cases of developmental stenosis or because of soft disc herniation. Moreover, patients with soft cervical disc herniation have a significantly smaller sagittal diameter of the bony spinal canal, a significantly smaller minimal bony intervertebral foramen diameter, and a significantly smaller cross-sectional area of the bony cervical canal than do healthy matched individuals.