Rotation-activity relations and flares of M dwarfs with K2 long- and short-cadence data

Abstract

Using light curves obtained by the K2 mission, we study the relation between stellar rotation and magnetic activity with special focus on stellar flares. Our sample comprises 56 bright and nearby M dwarfs observed by K2 during campaigns C0-C18 in long- and short-cadence mode. We derive rotation periods for 46 M dwarfs and measure photometric activity indicators such as amplitude of the rotational signal, standard deviation of the light curves, and the basic flare properties (flare rate, flare energy, flare duration, and flare amplitude). We found 1662 short-cadence flares, 363 of which have a long-cadence counterpart with flare energies of up to $5.6\cdot 10^{34}$erg. The flare amplitude, duration, and frequency derived from the short-cadence light curves differ significantly from those derived from the long-cadence data. The analysis of the short-cadence light curves results in a flare rate that is 4.6 times higher than the long-cadence data. We confirm the abrupt change in activity level in the rotation-activity relation at a critical period of ~10d when photometric activity diagnostics are used. This change is most drastic in the flare duration and frequency for short-cadence data. Our flare studies revealed that the highest flare rates are not found among the fastest rotators and that stars with the highest flare rates do not show the most energetic flares. We found that the superflare frequency ($E\ge 5\cdot 10^{34}$erg) for the fast-rotating M stars is twice higher than for solar like stars in the same period range. By fitting the cumulative FFD, we derived a power-law index of $\alpha =1.84\pm 0.14$, consistent with previous M dwarf studies and the value found for the Sun.

23 pages, 26 figures, 7 tables

References in corpus (24)

• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• The K2 Mission: Characterization and Early results
• Astrophysics Source Code Library
• How to Constrain Your M Dwarf: measuring effective temperature, bolometric luminosity, mass, and radius
• A Technique for Extracting Highly Precise Photometry for the Two-Wheeled Kepler Mission
• Measuring the rotation period distribution of field M-dwarfs with Kepler
• Kepler Flares I. Active and Inactive M dwarfs
• The H$\alpha$ emission of nearby M dwarfs and its relation to stellar rotation
• The Kepler Catalog of Stellar Flares
• Kepler Flares II: The Temporal Morphology of White-Light Flares on GJ 1243
• EVEREST: Pixel Level Decorrelation of K2 Light curves
• Solar-type dynamo behaviour in fully convective stars without a tachocline
• Do Kepler superflare stars really include slowly-rotating Sun-like stars ? - Results using APO 3.5m telescope spectroscopic observations and Gaia-DR2 data -
• K2 rotation periods for low-mass Hyads and a quantitative comparison of the distribution of slow rotators in the Hyades and Praesepe
• M Dwarfs in SDSS Stripe 82: Photometric Light Curves and Flare Rate Analysis
• A path towards understanding the rotation-activity relation of M dwarfs with K2 mission, X-ray and UV data
• The Evolution of Flare Activity with Stellar Age
• Relation of X-ray activity and rotation in M dwarfs and predicted time-evolution of the X-ray luminosity
• A statistical analysis of X-ray variability in pre-main sequence objects of the Taurus Molecular Cloud
• Flares in Open Clusters with K2. I. M45 (Pleiades), M44 (Praesepe) and M67
• The Near-Ultraviolet Luminosity Function of Young, Early M-Type Dwarf Stars
• Activity and Kinematics of White Dwarf-M Dwarf Binaries from the SUPERBLINK Proper Motion Survey
• Superflares on the slowly rotating solar-type stars KIC10524994 and KIC07133671?
• The M4 Transition: Toward a comprehensive understanding of the transition into the fully convective regime

Cited by in corpus (32)

• Relation of X-ray activity and rotation in M dwarfs and predicted time-evolution of the X-ray luminosity
• Flares in Open Clusters with K2. II. Pleiades, Hyades, Praesepe, Ruprecht 147, and M67
• X-ray Super-Flares From Pre-Main Sequence Stars: Flare Energetics And Frequency
• First eROSITA study of nearby M dwarfs and the rotation-activity relation in combination with TESS
• Extending Optical Flare Models to the UV: Results from Comparing of TESS and GALEX Flare Observations For M Dwarfs
• Testing Self-Organized Criticality Across the Main Sequence using Stellar Flares from TESS
• Activity of TRAPPIST-1 analogue stars observed with TESS
• A Study of Flares in the Ultra-Cool Regime from SPECULOOS-South
• 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
• Testing the Limits of Precise Subgiant Characterization with APOGEE and Gaia: Opening a Window to Unprecedented Astrophysical Studies
• The Variable Detection of Atmospheric Escape around the young, Hot Neptune AU Mic b
• New Time-Resolved, Multi-Band Flares In The GJ 65 System With gPhoton
• The corona of GJ 1151 in the context of star-planet interaction
• Simultaneous Detection of Optical Flares of the Magnetically Active M Dwarf Wolf 359
• Effects of flares on the habitable zones of M dwarfs accessible to TESS planet detections
• Magnetic activities and parameters of 43 flare stars in the GWAC archive
• Estimating the Convective Turnover Time
• A Study of the Magnetic Activity and Variability of GJ 436
• Exploring the short-term variability of H$\alpha$ and H$\beta$ emissions in a sample of M dwarfs
• Simultaneous X-ray and optical variability of M dwarfs observed with eROSITA and TESS
• The rotation-activity relation of M dwarfs: From K2 to TESS and PLATO
• The white-light superflares from cool stars in GWAC triggers
• Theoretical and Observational Evidence for Coriolis Effects in Coronal Magnetic Fields Via Direct Current Driven Flaring Events
• Detection of an energetic flare from the M5V secondary star in the Polar MQ Dra
• Long-term stellar activity of M dwarfs: A combined K2 and TESS study of two early M-type stars
• Detecting stellar flares in photometric data using hidden Markov models
• Enhancing the detection of low-energy M dwarf flares: Wavelet-based denoising of CHEOPS data
• Flare frequency in M dwarfs belonging to Young Moving Groups
• Flaring Latitudes in Ensembles of Low Mass Stars
• CaII and H$\alpha$ flaring M dwarfs detected with multi-filter photometry
• Exploring stellar activity in a sample of active M dwarfs