Three Eruptions Observed by Remote Sensing Instruments Onboard Solar Orbiter

On February 21 and March 21 – 22, 2021, the Extreme Ultraviolet Imager (EUI) onboard Solar Orbiter observed three prominence eruptions. The eruptions were associated with coronal mass ejections (CMEs) observed by Metis, Solar Orbiter’s coronagraph. All three eruptions were also observed by instruments onboard the Solar–TErrestrial RElations Observatory (Ahead; STEREO-A), the Solar Dynamics Observatory (SDO), and the Solar and Heliospheric Observatory (SOHO). Here we present an analysis of these eruptions. We investigate their morphology, direction of propagation, and 3D properties. We demonstrate the success of applying two 3D reconstruction methods to three CMEs and their corresponding prominences observed from three perspectives and different distances from the Sun. This allows us to analyze the evolution of the events, from the erupting prominences low in the corona to the corresponding CMEs high in the corona. We also study the changes in the global magnetic field before and after the eruptions and the magnetic field configuration at the site of the eruptions using magnetic field extrapolation methods. This work highlights the importance of multi-perspective observations in studying the morphology of the erupting prominences, their source regions, and associated CMEs. The upcoming Solar Orbiter observations from higher latitudes will help to constrain this kind of study better

Accélération et chauffage des ions lourds dans le vent solaire rapide : modélisations et comparaisons expérimentales

Ion cyclotron resonance is used in models to provide the necessary contribution to the acceleration of the fast solar wind, and sometimes to heat the solar corona. It is often combined with an Alfvén waves turbulence cascade, the ion cyclotron waves being the high-frequency limit at which energy is dissipated in the solar plasma. These models are supported by features of the ion velocity distributions observed both in the upper corona (spectroscopically) and in the solar wind (in situ), like preferential heating as a function of the charge-to-mass ratio (q/m), anisotropies of temperature, or differential speeds. The main purpose of this thesis is to constrain the power found in the waves and dissipated in the corona, by observing signatures of Alfvén and cyclotron waves in the lower corona (This study revealed two signatures of preferential heating above a coronal hole : ions having the lowest q/m are the hottest ones at the considered altitudes, and they also experience the largest heating when the altitude increases. Besides, curves of temperature as a function of q/m show a similar trend above a "Quiet Sun" region, which suggests that the cyclotron resonance is occurring at all latitudes. Using these results, I proposed some guidelines on the modelling of energy exchanges between waves, minor ions, and protons in the corona.La résonance cyclotronique ionique est utilisée dans certains modèles pour fournir la contribution nécessaire à l'accélération du vent solaire "rapide", voire pour chauffer la couronne solaire. Elle est souvent associée, dans ces modèles, à une cascade turbulente d'ondes d'Alfvén, dont les ondes cyclotroniques ioniques constituent la limite haute-fréquence. Ces modèles s'appuient en particulier sur certaines caractéristiques des distributions cinétiques ioniques observées dans la haute couronne (par spectroscopie) et dans le vent solaire (mesures in situ), telles que chauffage préférentiel en fonction du rapport charge-sur-masse (q/m), anisotropies de températures, ou vitesses différentielles. L'objet principal de cette thèse consiste à mettre en évidence des signatures d'ondes d'Alfvén et d'ondes cyclotroniques dans la basse couronne solaire (Pour cela, j'ai utilisé les largeurs des raies coronales appartenant à des ions de différents q/m, observées à l'aide du spectromètre SUMER opérant dans l'extrême-UV, et embarqué à bord du satellite SOHO. J'ai séparé les deux principales contributions à ces largeurs : effets Doppler thermique et "non-thermique" (lequel est potentiellement dû à la présence d'ondes d'Alfvén), en analysant le gradient des largeurs en fonction de l'altitude au dessus du limbe solaire. Lors de ce travail, j'ai montré l'importance de corriger les profils de raies observés de l'effet de la lumière diffusée instrumentale. J'ai mis en évidence deux signatures de chauffage préférentiel dans un trou coronal : les ions de plus petits q/m sont plus chauds que les autres à une altitude donnée, et ils sont davantage chauffés quand l'altitude augmente. Par ailleurs, les courbes de températures en fonction de q/m présentent une tendance similaire dans un trou coronal et dans une région de "soleil calme", ce qui laisse penser que la résonance cyclotronique ionique se produit à toutes les latitudes. Ces résultats me permettent de suggérer quelques pistes pour la modélisation des échanges entre ondes, ions minoritaires et protons

Accélération et chauffage des ions lourds dans le vent solaire rapide (modélisations et comparaisons expérimentales)

La résonance cyclotronique ionique est utilisée dans certains modèles pour fournir la contribution nécessaire à l'accélération du vent solaire "rapide", voire pour chauffer la couronne solaire. Elle est souvent associée, dans ces modèles, à une cascade turbulente d'ondes d'Alfvén, dont les ondes cyclotroniques ioniques constituent la limite haute-fréquence.L'objet principal de cette thèse consiste à mettre en évidence des signatures d'ondes d'Alfvén et d'ondes cyclotroniques dans la basse couronne solaire (<1.5 rayons solaires), dans l'intention de mieux contraindre l'énergie réellement présente sous forme d'ondes, et celle effectivement dissipée dans la couronne.Pour cela, j'ai utilisé les largeurs des raies coronales appartenant à des ions de différents q/m, observées à l'aide du spectromètre SUMER opérant dans l'extrême-UV, et embarqué à bord du satellite SOHO. J'ai séparé les deux principales contributions à ces largeurs : effets Doppler thermique et "non-thermique" (lequel est potentiellement dû à la présence d'ondes d'Alfvén), en analysant le gradient des largeurs en fonction de l'altitude au dessus du limbe solaire. Lors de ce travail, j'ai montré l'importance de corriger les profils de raies observés de l'effet de la lumière diffusée instrumentale.J'ai mis en évidence deux signatures de chauffage préférentiel dans un trou coronal : les ions de plus petits q/m sont plus chauds que les autres à une altitude donnée, et ils sont davantage chauffés quand l'altitude augmente. Par ailleurs, les courbes de températures en fonction de q/m présentent une tendance similaire dans un trou coronal et dans une région de "soleil calme", ce qui laisse penser que la résonance se ...Ion cyclotron resonance is used in models to provide the necessary contribution to the acceleration of the fast solar wind, and sometimes to heat the solar corona. It is often combined with an Alfvén waves turbulence cascade, the ion cyclotron waves being the high-frequency limit at which energy is dissipated in the solar plasma. The main purpose of this thesis is to constrain the power found in the waves and dissipated in the corona, by observing signatures of Alfvén and cyclotron waves in the lower corona (<1.5 solar radii). I studied for that the linewidths of coronal ions having different q/m, using the EUV-spectrometer SUMER (on board SOHO). The two main contributions in these linewidths (thermal and "non-thermal" Doppler effects, the latter potentially due to the presence of Alfvén waves) were separated by analysing the gradient of the widths above the solar limb. While doing so, I pointed out the importance of correcting the line profiles from the contribution of the instrumental stray light. This study revealed two signatures of preferential heating above a coronal hole : ions having the lowest q/m are the hottest ones at the considered altitudes, and they also experience the largest heating when the altitude increases. Besides, curves of temperature as a function of q/m show a similar trend above a "Quiet Sun" region, which suggests that the cyclotron resonance is occurring at all latitudes.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Possible measurements of the magnetic field in eruptive prominences using the PROBA-3 coronagraph

International audienceThe PROBA-3 mission will fly a spacecraft put in the shadow of a precisely occulting sister satellite orbiting “in formation” at a distance of 150 m in front of it to make artificial total eclipses. The region right above the solar limb will be studied for the first time over a coronal background not polluted by any spurious light. Although the priority will be the high-resolution fast imaging of the dynamic white-light corona, the use of a narrow filter centered on a low excitation D3 line of He I, is planned for imaging prominences. Adding the linear polarization analysis would permit the measurements of the magnetic field using the Hanle effect. We evaluate the possibility offered during the eruptive phase of a CME with prominence material inserted inside, for studying the associated magnetic field changes related to both the heating process and the ejection of material. The background highly polarized K-corona is taken into account. Sequences of quasi- simultaneous white-light processed images at high resolution are an additional feature of great interest for interpreting the overall magnetic structure

Evaluation of long-term sequelae by cardiopulmonary exercise testing 12 months after hospitalization for severe COVID-19

Abstract Background Cardiopulmonary exercise testing (CPET) is an important clinical tool that provides a global assessment of the respiratory, circulatory and metabolic responses to exercise which are not adequately reflected through the measurement of individual organ system function at rest. In the context of critical COVID-19, CPET is an ideal approach for assessing long term sequelae. Methods In this prospective single-center study, we performed CPET 12 months after symptom onset in 60 patients that had required intensive care unit treatment for a severe COVID-19 infection. Lung function at rest and chest computed tomography (CT) scan were also performed. Results Twelve months after severe COVID-19 pneumonia, dyspnea was the most frequently reported symptom although only a minority of patients had impaired respiratory function at rest. Mild ground-glass opacities, reticulations and bronchiectasis were the most common CT scan abnormalities. The majority of the patients (80%) had a peak O2 uptake (V′O2) considered within normal limits (median peak predicted O2 uptake (V′O2) of 98% [87.2–106.3]). Length of ICU stay remained an independent predictor of V′O2. More than half of the patients with a normal peak predicted V′O2 showed ventilatory inefficiency during exercise with an abnormal increase of physiological dead space ventilation (VD/Vt) (median VD/VT of 0.27 [0.21–0.32] at anaerobic threshold (AT) and 0.29 [0.25–0.34] at peak) and a widened median peak alveolar-arterial gradient for O2 (35.2 mmHg [31.2–44.8]. Peak PetCO2 was significantly lower in subjects with an abnormal increase of VD/Vt (p = 0.001). Impairments were more pronounced in patients with dyspnea. Peak VD/Vt values were positively correlated with peak D-Dimer plasma concentrations from blood samples collected during ICU stay (r2 = 0.12; p = 0.02) and to predicted diffusion capacity of the lung for carbon monoxide (DLCO) (r2 =  − 0.15; p = 0.01). Conclusions Twelve months after severe COVID-19 pneumonia, most of the patients had a peak V′O2 considered within normal limits but showed ventilatory inefficiency during exercise with increased dead space ventilation that was more pronounced in patients with persistent dyspnea. Trial registration: NCT04519320 (19/08/2020)

Full Vector Velocity Reconstruction Using Solar Orbiter Doppler Map Observations.

International audienceThe Solar Orbiter mission opens up opportunities forthe combined analysis of measurements obtained by solar imagers and spectrometers. For the first time, different space spectrometerswill be located at wide angles to each other, allowing three-dimensional (3D) spectroscopy of the solar atmosphere.The aim of this work is to prepare the methodology to facilitate the reconstruction of 3D vector velocities from two stereoscopicLOS Doppler velocity measurements using the Spectral Imaging of the Coronal Environment (SPICE) on board the Solar Orbiter andthe near-Earth spectrometers, while widely separated in space. We develop the methodology using the libraries designed earlier for the STEREO mission but applied to spectroscopicdata from the Hinode mission and the Solar Dynamics Observatory. We use well-known methods of static and dynamic solar rotationstereoscopy and the methods of EUV stereoscopic triangulation for optically-thin coronal EUV plasma emissions. We develop new algorithms using analytical geometry in space to determine the 3D velocity in coronal loops. We demonstrate our approach with the reconstruction of 3D velocity vectors in plasma flows along "open" and "closed"magnetic loops. This technique will be applied first to an actual situation of two spacecraft at different separations with spectrometers onboard (SPICE versus the Interface Region Imaging Spectrograph (IRIS) and Hinode imaging spectrometer) during the Solar Orbiternominal phase. We summarise how these observations can be coordinated

First Detection of Solar Flare Emission in Mid-ultraviolet Balmer Continuum

International audienceWe present the first detection of solar flare emission at middle-ultraviolet wavelengths around 2000Å by the channel 2 of the Large-Yield RAdiometer (LYRA) onboard the PROBA2 mission. The flare (SOL20170906) was also observed in the channel 1 of LYRA centered at the H I Lyman-α line at 1216Å, showing a clear non-thermal profile in both channels. The flare radiation in channel 2 is consistent with the hydrogen Balmer continuum emission produced by an optically thin chromospheric slab heated up to 10000 K. Simultaneous observations in channels 1 and 2 allow the separation of the line emission (primarily from the Lyman-α line) from the Balmer continuum emission. Together with the recent detection of the Balmer continuum emission in the near-ultraviolet by IRIS, the LYRA observations strengthen the interpretation of broadband flare emission as the hydrogen recombination continua originating in the chromosphere