White Light Flare Rates of M5-L5 dwarfs using K2 data

The K2 mission's unique combination of wide area coverage and continuous time coverage over months has enabled us to study white light flare rates of cool stars of various spectral types. We have shown that the white light flares are ubiquitous in some late-M and early L dwarfs. Some early L dwarfs are even capable of producing superflares with bolometric flare energies greater than 10³³ erg despite having lower effective temperatures. We update our results on the white light flare rates of very-low-mass stars with a wide range of spectral types: M5-L5, obtained by using both short cadence (~1 min) and long cadence (~30 min) K2 data. We analyze the possible relation between flare rates of very-low-mass stars in our sample and different properties like spectral type, age, etc. Strong magnetic fields of order of 5-10 kilogauss are required to explain the most energetic flares. Using constraints on magnetic fields from the biggest flares, we discuss the nature and evolution of the magnetic dynamo on very-low-mass stars. Our results will be helpful in predicting the number of flares on the low-mass cool stars which will be observed by future photometric surveys like TESS.