Observations and modeling of spectral line asymmetries in stellar flare

0570191 - ASÚ 2024 RIV FR eng J - Článek v odborném periodiku
Wollmann, J. - Heinzel, Petr - Kabáth, Petr
Observations and modeling of spectral line asymmetries in stellar flare.
Astronomy & Astrophysics. Roč. 669, January (2023), č. článku A118. ISSN 0004-6361. E-ISSN 1432-0746
Grant CEP: GA ČR(CZ) GA19-17102S; GA MŠMT(CZ) LTT20015
Institucionální podpora: RVO:67985815
Klíčová slova: stars * flare * late-type
Obor OECD: Astronomy (including astrophysics,space science)
Impakt faktor: 6.5, rok: 2022
Způsob publikování: Open access

We observed the dMe star AD Leo using the 2-meter Perek telescope at Ondrejov observatory, with simultaneous photometric light curves. In analogy with solar flares, we modeled the H alpha line emergent from an extensive arcade of cool flare loops and explain the observed asymmetries using the concept of coronal rain.Methods. We solved the non-LTE (departures from local thermal equilibrium) radiative transfer in H alpha within cool flare loops taking the velocity distribution of individual rain clouds into account. For a flare occurring at the center of the stellar disk, we then integrated radiation emergent from the whole arcade to obtain the flux from the loop area. We observed two flares in the H alpha line that exhibit a red wing asymmetry corresponding to velocities up to 50 km s(-1) during the gradual phase of the flare. Synthetic profiles generated from the model of coronal rain have enhanced red wings that are quite compatible with observations.
Trvalý link: https://hdl.handle.net/11104/0341976