Flare Activity and Magnetic Feature Analysis of the Flare Stars. III. K-type Dwarf Binary Components

Abstract We analyze the light curve of 199 dwarf stars that are members of binary systems resolved by Kepler mission. All of them are K-type active stars in binary systems of which their flare activity has been confirmed. From the light-curve modulation, we can infer stability, relative coverage, and contrast of the magnetic structures. In addition, we extract the flare component from the light-curve fluctuations and study the flare characteristics such as total time duration, power, and flux magnitude. These magnetic activity indicators show the same dependency to the Rossby number such as single main-sequence (MS) stars and have the same saturation or supersaturation behavior at high rotation rates. Also, while the average rotation period of the binary sample is much lower than single MS and subgiant branch (SGB), their flare activity level is just slightly higher than the single MS and is lower than the single SGB stars. This shows that the production of magnetic fields through a dynamo procedure is more affected by the convective depth rather than the rotation period. Furthermore, the presence of the companion star and spinning up of the rotation period has a greater effect on the relative coverage and contrast of the magnetic features than the flare activity.