Contributed Talk - Splinter eROSITA
A first eROSITA view of stellar coronae across the HR diagram
E. Magaudda^1, B. Stelzer^1,2, St. Raetz^1, A. Klutsch^1, M. Salvato^3, J. Wolf^3, M. Coffaro^1, W. Joseph^1 and M. Epple^1
(1) Institut für Astronomie und Astrophysik, Eberhard-Karls Universität Tübingen, Sand 1, D-72076 Tübingen, Germany and (2) INAF- Osservatorio Astronomico di Palermo, Piazza Parlamento 1, I-90134 Palermo, Italy and (3) Max-Planck-Institut für extraterrestrische Physik, Giessenbachstr. 1, 85748 Garching, Germany and Exzellenzcluster ORIGINS, Boltzmannstr. 2, D-85748 Garching, Germany
I present an overview of the X-ray emission from stellar coronae observed with the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) on board the Spektrum-Roentgen-Gamma satellite. X-ray activity is currently studied by us as part of the eROStars group in such different objects as protostars, solar-like stars, M dwarfs, and Ultracool dwarfs (UCDs). In these projects we address a variety of science questions, from the search for activity cycles over the relation between X-ray emission and stellar rotation rate to the detection of faint objects. We make use both of the all-sky capability of eROSITA to build statistical samples and of its multi-epoch data providing a so far two-year long baseline for variability studies (through completion of the first four surveys). Short-term flaring variability is assessed from the subsequent visits of eROSITA to a given source within each survey which yields a time-resolution of four hours. Finally, a particular asset is the complementary optical all-sky survey carried out with the Transiting Exoplanet Survey Satellite (TESS) that provides rotation periods and optical activity diagnostics for many eROSITA-detected stars, and for the first time in history a sizeable amount of such optical measurements are simultaneous with the X-ray data.