Simultaneous X-ray and optical variability of M dwarfs observed with eROSITA and TESS
arXiv:2401.17287 · doi:10.1051/0004-6361/202449405
Abstract
We study variability through simultaneous optical and X-ray observations for the first time in a statistical sample of 256 M dwarfs. Such observations are required to constrain the flare frequency and energetics and to understand the physics of flares. Using light curves from extended ROentgen Survey with an Imaging Telescope Array (eROSITA) on board the Russian Spektrum-Roentgen-Gamma mission (SRG) and the Transiting Exoplanet Survey Satellite (TESS), we identify 256 M dwarfs with simultaneous detections. The 25 brightest or most variable in X-rays are selected. Stellar parameters are obtained from Gaia and 2MASS, while X-ray fluxes are derived from eROSITA count rates. Proximity (<100 pc), fast rotation (P_rot < 9 d), and high flare frequency characterize our sample. Optical and X-ray duty cycles correlate positively, with faster rotators exhibiting more variability. Stars with frequent X-ray flares often coincide with optical flares. Analyzing individual X-ray flares is hindered by eROSITA's low cadence, mitigated by leveraging TESS optical flares and solar flare knowledge. An exponential fit to 21 X-ray light curves post-optical flares reveals a correlation between X-ray and optical flare energies. Despite uncertainties due to poor eROSITA sampling, our study underscores the significance of simultaneous all-sky surveys in diverse wavelengths for unprecedented insights into stellar variability.
References in corpus (29)
- Array Programming with NumPy
- The Gaia mission
- The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
- How to Constrain Your M Dwarf: measuring effective temperature, bolometric luminosity, mass, and radius
- Measuring the rotation period distribution of field M-dwarfs with Kepler
- The SRG X-ray orbital observatory, its telescopes and first scientific results
- Kepler Flares I. Active and Inactive M dwarfs
- The SRG/eROSITA all-sky survey: First X-ray catalogues and data release of the western Galactic hemisphere
- The eROSITA Final Equatorial Depth Survey (eFEDS): The X-ray catalog
- A Re-appraisal of the Habitability of Planets Around M Dwarf Stars
- Kepler Flares II: The Temporal Morphology of White-Light Flares on GJ 1243
- Generalized investigation of the rotation-activity relation: Favouring rotation period instead of Rossby number
- A path towards understanding the rotation-activity relation of M dwarfs with K2 mission, X-ray and UV data
- Superflare occurrence and energies on G-, K- and M-type dwarfs
- Relation of X-ray activity and rotation in M dwarfs and predicted time-evolution of the X-ray luminosity
- Multiwavelength observations of a giant flare on CN Leonis I. The chromosphere as seen in the optical spectra
- No Such Thing as a Simple Flare: Substructure and QPPs Observed in a Statistical Sample of 20 Second Cadence TESS Flares
- Simultaneous optical and X-ray observations of a giant flare on the ultracool dwarf LP412-31
- Optical and X-ray observations of stellar flares on an active M dwarf AD Leonis with Seimei Telescope, SCAT, NICER and OISTER
- First eROSITA study of nearby M dwarfs and the rotation-activity relation in combination with TESS
- Simultaneous Kepler/K2 and XMM-Netwon observations of superflares in the Pleiades
- A coronal explosion on the flare star CN Leonis
- Stellar Superflares Observed Simultaneously with Kepler and XMM-Newton
- Flares and rotation of M dwarfs with habitable zones accessible to TESS planet detections
- The Great Flare of 2021 November 19 on AD Leo. Simultaneous XMM-Newton and TESS observations
- TESS Habitable Zone Star Catalog
- X-ray/H scaling relationships in stellar flares
- Simultaneous eROSITA and TESS observations of the ultra-active star AB~Doradus
- First eROSITA-TESS results for M dwarfs: Mass dependence of the X-ray activity rotation relation and an assessment of sensitivity limits