Cool Spot and Flare Activities of a RS CVn Binary KIC 7885570

TL;DR

This study analyzes the chromospheric activity, spot behavior, and flare characteristics of the RS CVn binary KIC 7885570 using Kepler data, revealing dynamic spot changes, flare properties, and low magnetic activity levels.

Contribution

First detailed analysis of spot activity and flare behavior in KIC 7885570 based on Kepler data, including modeling of spot evolution and flare parameters.

Findings

Two rapidly changing spotted areas on the secondary component.

113 flares detected with a specific exponential decay model.

Low magnetic activity level consistent with B-V color index.

Abstract

We present here the results on the physical nature a RS CVn binary KIC 7885570 and its chromospheric activity based on the Kepler Mission data. Assuming the primary component temperature, 6530 K, the temperature of the secondary component was found to be 5732+-4 K. The mass ratio of the components (q) was found to be 0.43$\pm$0.01, while the inclination ($i$) of the system 80.56+-0.01 deg. Additionally, the data were separated into 35 subsets to model the sinusoidal variation due to the rotational modulation, using the SPOTMODEL program, as the light curve analysis indicated the chromospherically active secondary component. It was found that there are generally two spotted areas, whose radii, longitudes and latitudes are rapidly changing, located around the latitudes of +50 deg and +90 deg on the active component. Moreover, 113 flares were detected and their parameters were computed from the available data. The One Phase Exponential Association function model was derived from the parameters of these flares. Using the regression calculations, the Plateau value was found to be 1.9815+-0.1177, while the half-life value was computed as 3977.2 s. In addition, the flare frequency (N1) - the flare number per hour, was estimated to be 0.00362 1/h, while flare frequency (N2) - the flare-equivalent duration emitted per hour, was computed as 0.00001. Finally, the times of eclipses were computed for 278 minima of the light curves, whose analysis indicated that the chromosphere activity nature of the system causes some effects on these minima times. Comparing the chromospheric activity patterns with the analogues of the secondary component, it is seen that the magnetic activity level is remarkably low. However, it is still at the expected level according to the B-V color index of 0.643 mag for the secondary component.