Abstract

Poster - Plenary

Connecting the coronae and photospheres of M Dwarfs with eROSITA and TESS

Anirudh Srikant Thakar, Beate Stelzer
Institut für Astronomie und Astrophysik Tübingen (IAAT), Sand 1, 72076, Tübingen, Germany

M Dwarfs are the most abundant stars in the Galaxy. Magnetic activity is a hallmark of these stars. Yet the connection between the relation of magnetic activity produced in different layers of their atmospheres is not fully explored yet. In this work, which forms part of my Master’s thesis, I analyze a unique sample of 340 nearby (d ≲ 100 pc) M dwarfs observed simultaneously in optical and X-ray wavelengths using data from the Transiting Exoplanet Survey Satellite’s Year 3 (TESS) and the extended ROentgen Survey with an Imaging Telescope Array’s (eROSITA) eRASS2 and eRASS3 internal data releases, respectively. Optical data from TESS provides the rotation periods and amplitudes of rotational modulation due to spots on the photosphere of the stars. Data from eROSITA provides the X-ray brightness of the corona of the stars. By correlating simultaneous data from this sample, I examine the relation between starspot modulation amplitude, photometric magnetic activity index and X-ray brightness. In addition, I will also present the classical X-ray activity and rotation relation with new constraints on the activity level of saturated stars and its dependence on the spectral type subclass (from M0 to M6). The data represents (one of) the largest sample(s) of contemporaneous X-ray and optical observations, yielding a crucial observational test bed for the multi-wavelength variability of magnetically active stars.