Exploring stellar activity in a sample of active M dwarfs

Abstract

Most M dwarfs show higher chromospheric activity, often exceeding solar levels. Characterizing stellar activity is essential, particularly since these stars are prime targets in the search for habitable exoplanets. We investigate the stellar activity of active M dwarfs using TESS photometry combined with spectroscopic observations. We explore relations between flare occurrence rate (FOR), flare energies, rotation period, starspot filling factor, and chromospheric indicators. We also examine correlations between flare amplitude, duration, and cumulative flare frequency distributions to probe the mechanisms behind magnetic activity. We find that FOR is flat across spectral types M0-M4 but declines for cooler M dwarfs. Rapid rotators ($P_{\mathrm{rot}}<1$ day) display significantly higher FOR and flare activity. M dwarfs with higher FOR tend to have lower flare amplitudes, suggesting that frequent flares are generally less energetic. For stars with 0.15--0.76 $M_{\odot }$, the median $L_{H\alpha }/L_{\mathrm{bol}}$ varies by a factor of 2.5 across mass bins of 0.1 $M_{\odot }$, while $\Delta$EW decreases by 92\%. The cumulative flare frequency distributions show a decrease in the power-law slope from M0 to M5, with $\alpha$ ranging from 1.68 to 1.95. Our results indicate a transition in stellar activity near M4, where stronger H$\alpha$ emission coincides with higher FOR. We confirm that chromospheric and flare activity follow a power-law relation, highlighting the interplay between magnetic fields and flaring in M dwarfs. We also find that fast rotators sustain frequent flaring through strong dynamos, and that highly active stars dissipate magnetic energy via numerous low-energy flares rather than rare high-energy ones.

18 pages, 16 figures, 4 tables, accepted for publication in Astronomy & Astrophysics

References in corpus (61)

• The Transiting Exoplanet Survey Satellite
• The K2 Mission: Characterization and Early results
• A terrestrial planet candidate in a temperate orbit around Proxima Centauri
• The stellar activity-rotation relationship and the evolution of stellar dynamos
• How to Constrain Your M Dwarf: measuring effective temperature, bolometric luminosity, mass, and radius
• The TESS Input Catalog and Candidate Target List
• Superflares on Solar Type Stars Observed with Kepler I. Statistical Properties of Superflares
• Kepler Flares I. Active and Inactive M dwarfs
• The H$\alpha$ emission of nearby M dwarfs and its relation to stellar rotation
• Spectroscopic Properties of Cool Stars in the SDSS: An Analysis of Magnetic Activity and a Search for Subdwarfs
• Stellar Flares from the First Tess Data Release: Exploring a New Sample of M-dwarfs
• The Kepler Catalog of Stellar Flares
• Kepler Flares II: The Temporal Morphology of White-Light Flares on GJ 1243
• The formation of the Halpha line in the solar chromosphere
• Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18
• StarHorse: A Bayesian tool for determining stellar masses, ages, distances, and extinctions for field stars
• Modeling Repeated M-dwarf Flaring at an Earth-like Planet in the Habitable Zone: I. Atmospheric Effects for an Unmagnetized Planet
• Long-term magnetic activity of a sample of M-dwarf stars from the HARPS program I. Comparison of activity indices
• The Solar Neighborhood XXXVII: The Mass-Luminosity Relation for Main Sequence M Dwarfs
• A catalogue of rotation and activity in early-M stars
• The Habitable-Zone Planet Finder: A Stabilized Fiber-Fed NIR Spectrograph for the Hobby-Eberly Telescope
• Superflares on Solar-Type Stars Observed with Kepler II. Photometric Variability of Superflare-Generating Stars : A Signature of Stellar Rotation and Starspots
• White-light flares on cool stars in the Kepler Quarter 1 Data
• Sun-as-a-star Observation of White-Light Flares
• Fluxes in Hαand Ca II H and K for a sample of Southern stars
• An Activity-Rotation Relationship and Kinematic Analysis of Nearby Mid-to-Late-type M Dwarfs
• The HARPS search for southern extra-solar planets XLI. A dozen planets around the M dwarfs GJ 3138, GJ 3323, GJ 273, GJ 628, and GJ 3293
• Photometric Amplitude Distribution of Stellar Rotation of Kepler KOIs-Indication for Spin-Orbit Alignment of Cool Stars and High Obliquity for Hot Stars
• Near and Mid-IR Photometry of the Pleiades, and a New List of Substellar Candidate Members
• The 10 parsec sample in the Gaia era
• Flare Statistics for Young Stars from a Convolutional Neural Network Analysis of $\text{TESS}$ Data
• H-alpha Activity of Old M Dwarfs: Stellar Cycles and Mean Activity Levels For 93 Low-Mass Stars in the Solar Neighborhood
• 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
• M Dwarf Flares from Time-Resolved SDSS Spectra
• Relation of X-ray activity and rotation in M dwarfs and predicted time-evolution of the X-ray luminosity
• Semi-empirical Modeling of the Photosphere, Chromosphere, Transition Region, and Corona of the M-dwarf Host Star GJ 832
• The magnetic field and multiple planets of the young dwarf AU~Mic
• Flares in Open Clusters with K2. II. Pleiades, Hyades, Praesepe, Ruprecht 147, and M67
• Evidence for photometric activity cycles in 3203 Kepler stars
• Investigating the Rotational Phase of Stellar Flares on M dwarfs Using K2 Short Cadence Data
• Stellar activity with LAMOST. I. Spot configuration in Pleiades
• One year of AU Mic with HARPS: II -- stellar activity and star-planet interaction
• On the relationship between the size and surface coverage of starspots on magnetically active low-mass stars
• Probing the Origin of Stellar Flares on M dwarfs Using TESS Data Sectors 1-3
• The radii of M-dwarfs in the young open cluster NGC 2516
• Stellar flares detected with the Next Generation Transit Survey
• Rotation-activity relations and flares of M dwarfs with K2 long- and short-cadence data
• White-Light Flares on Close Binaries Observed with Kepler
• LAMOST Observations of Flaring M Dwarfs in the Kepler Field
• The HD 260655 system: Two rocky worlds transiting a bright M dwarf at 10 pc
• The CARMENES search for exoplanets around M dwarfs, Wolf 1069 b: Earth-mass planet in the habitable zone of a nearby, very low-mass star
• A new infrared Fabry-Pérot-based radial-velocity-reference module for the SPIRou radial-velocity spectrograph
• Short duration high amplitude flares detected on the M dwarf star KIC 5474065
• NIRPS joining HARPS at ESO 3.6 m. On-sky performance and science objectives
• Flares and rotation of M dwarfs with habitable zones accessible to TESS planet detections
• The CARMENES search for exoplanets around M dwarfs. Two terrestrial planets orbiting G 264-012 and one terrestrial planet orbiting Gl 393
• The spectroscopic binary system Gl 375. I. Orbital parameters and chromospheric activity
• Variability Timescales of H$\alpha$ on Active Mid-to-Late M dwarfs
• First Results from MFOSC-P : Low Resolution Optical Spectroscopy of a Sample of M dwarfs within 100 parsecs
• Exploring the short-term variability of H$\alpha$ and H$\beta$ emissions in a sample of M dwarfs

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