Photometric Flaring Fraction of M dwarf Stars from the SkyMapper Southern Survey

Abstract

We present our search for flares from M dwarf stars in the SkyMapper Southern Survey DR1, which covers nearly the full Southern hemisphere with six-filter sequences that are repeatedly observed in the passbands $uvgriz$. This allows us to identify bona-fide flares in single-epoch observations on timescales of less than four minutes. Using a correlation-based outlier search algorithm we find 254 flare events in the amplitude range of $\Delta u\sim 0.1$ to 5~mag. In agreement with previous work, we observe the flaring fraction of M dwarfs to increase from $\sim 30$ to $\sim$1,000 per million stars for spectral types M0 to M5. We also confirm the decrease in flare fraction with larger vertical distance from the Galactic plane that is expected from declining stellar activity with age. Based on precise distances from Gaia DR2, we find a steep decline in the flare fraction from the plane to 150~pc vertical distance and a significant flattening towards larger distances. We then reassess the strong type dependence in the flaring fraction with a volume-limited sample within a distance of 50~pc from the Sun: in this sample the trend disappears and we find instead a constant fraction of $\sim$1,650 per million stars for spectral types M1 to M5. Finally, large-amplitude flares with $\Delta i>1$ mag are very rare with a fraction of $\sim 0.5$ per million M dwarfs. Hence, we expect that M-dwarf flares will not confuse SkyMapper's search for kilonovae from gravitational-wave events.

13 pages, 11 figures, Accepted for publication in MNRAS

References in corpus (18)

• The Gaia mission
• Multi-messenger Observations of a Binary Neutron Star Merger
• Constraining the Age-Activity Relation for Cool Stars: The SDSS DR5 Low-Mass Star Spectroscopic Sample
• The Kepler Catalog of Stellar Flares
• Low-Mass Dwarf Template Spectra from the Sloan Digital Sky Survey
• SkyMapper Southern Survey: Second Data Release (DR2)
• Follow up of GW170817 and its electromagnetic counterpart by Australian-led observing programs
• The Solar Neighborhood XXXV: Distances to 1404 M Dwarf Systems Within 25 pc in the Southern Sky
• Estimating distances from parallaxes. III. Distances of two million stars in the Gaia DR1 catalogue
• M Dwarfs in SDSS Stripe 82: Photometric Light Curves and Flare Rate Analysis
• Radiative Hydrodynamic Models of Optical and Ultraviolet Emission from M Dwarf Flares
• Superflare occurrence and energies on G-, K- and M-type dwarfs
• Using the Galactic Dynamics of M7 Dwarfs to Infer the Evolution of Their Magnetic Activity
• A discontinuity in the $T_{\mathrm{eff}}$-radius relation of M-dwarfs
• Overview and stellar statistics of the expected Gaia Catalogue using the Gaia Object Generator
• The nature of the DLS fast transients
• The Palomar Transient Factory Sky2Night programme
• The M4 Transition: Toward a comprehensive understanding of the transition into the fully convective regime