High-resolution spectroscopy of flares and CMES on AD Leo*

Abstract

Flares and coronal mass ejections (CMEs) are important for the evolution of the atmospheres of planets and their potential habitability, particularly for planets orbiting M stars at a distance < 0.4 AU. Detections of CMEs on these stars have been sparse, and previous studies have therefore modelled their occurrence frequency by scaling up solar relations. However, because the topology and strength of the magnetic fields on M stars is different from that of the Sun, it is not obvious that this approach works well. We used a large number of high-resolution spectra to study flares, CMEs, and their dynamics of the active M dwarf star AD Leo. The results can then be used as reference for other M dwarfs. We obtained more than 2000 high-resolution spectra (R~35000) of the highly active M dwarf AD Leo, which is viewed nearly pole on. Using these data, we studied the behaviour of the spectral lines Halpha , Hbeta , and He I 5876 in detail and investigated asymmetric features that might be Doppler signatures of CMEs. We detected numerous flares. The largest flare emitted 8.32 x 10 31 erg in Hbeta and 2.12 x 10 32 erg in Halpha . Although the spectral lines in this and other events showed a significant blue asymmetry, the velocities associated with it are far below the escape velocity. Although AD Leo shows a high level of flare activity, the number of CMEs is relatively low. It is thus not appropriate to use the same flare-to-CME relation for M dwarfs as for the Sun.

10 pages, 7 figures, Accepted in A & A

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Cited by in corpus (9)

• Optical and X-ray observations of stellar flares on an active M dwarf AD Leonis with Seimei Telescope, SCAT, NICER and OISTER
• Sun-as-a-star Analyses of Various Solar Active Events Using H$\alpha$ Spectral Images Taken by SMART/SDDI
• 3D modelling of the impact of stellar activity on tidally locked terrestrial exoplanets: atmospheric composition and habitability
• Search for flares and associated CMEs on late-type main-sequence stars in optical SDSS spectra
• Detection of a high-velocity prominence eruption leading to a CME associated with a superflare on the RS CVn-type star V1355 Orionis
• The CARMENES search for exoplanets around M dwarfs: Stable radial-velocity variations at the rotation period of AD~Leonis -- A test case study of current limitations to treating stellar activity
• The GAPS programme at TNG XXVI. Magnetic activity in M stars: spectroscopic monitoring of AD Leonis
• The Flare-Activity of 2MASSJ16111534-1757214 in the Upper Scorpius association
• Flaring Latitudes in Ensembles of Low Mass Stars