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M dwarf flares

Statistical study of M dwarf flares in Stripe 82 is presented in Kowalski et al. 2009.

Flare example Stripe82.png
  • Colour range for M-dwarfs (r − i) > 0.53 and (i − z) > 0.3 and (u-r) > 3
  • The most flaring are late type M-dwarfs (M4-M6), earlier types (M2-M3) flare half as often as late types and M0-M1 dwarfs flare only 20% as often as late types.
  • flares are the most pronounced in u-band
  • around 35% of M-dwarfs are in binary systems - these have bluer u-g. Most single M-dwarfs will have u-g > 1.8
  • g - K > 4 - significantly brighter in IR (2MASS cross-match) than Visual.
  • amplitude in u > 0.7 mag up to 5 mag.
  • large and small flares possible on the same star
  • flaring fraction: 0.0108%, i.e. 1 of every 10,000 observation of a M-dwarf in Stripe 82 resulted in a flare
  • Sloan (5yrs) flaring star probabilities for different types of Mdwarf: M0-M1: 38/35,000; M2-M3: 79/13,000; M4-M6: 119/2120.
  • 1.3 flares per hour sq.deg with <math>\Delta u > 0.7</math> mag, with slightly more flares towards the galactic plane.

Ampitude distribution for Stripe82 flares.

Light curve examples

Mdwarf flare Gl234AB.png Example of flares in Gl234AB (V577 Mon) from Doyle et al. 1989

FlareCNLeo-PioftheSky.png Example flare detected by Pi of the Sky project. From Sokolowski 2008.

Outburst of the flare star CN Leo. From Sokolowski 2008.
High temporal resolution observations of a flare star by Pi of the Sky. From Sokolowski 2008.