Glimpses of stellar surfaces. I. Spot evolution and differential rotation of the planet host star Kepler-210

TL;DR

This study analyzes four years of Kepler data to investigate star spot evolution and differential rotation on Kepler-210, revealing persistent spot regions, evolving activity periods, and solar-like differential rotation patterns.

Contribution

It provides the first detailed analysis of spot evolution and differential rotation on Kepler-210 using a multi-season photometric approach.

Findings

Persistent spot regions at specific longitudes

Activity periods evolve similarly to solar cycles

Spot lifetimes estimated between 60 and 90 days

Abstract

We use high accuracy photometric data obtained with the Kepler satellite to monitor the activity modulations of the Kepler-210 planet host star over a time span of more than four years. Following the phenomenology of the star's light curve in combination with a five spot model, we identify six different so-called spot seasons. A characteristic, which is common in the majority of the seasons, is the persistent appearance of spots in a specific range of longitudes on the stellar surface. The most prominent period of the observed activity modulations is different for each season and appears to evolve following a specific pattern, resembling the changes in the sunspot periods during the solar magnetic cycle. Under the hypothesis that the star exhibits solar-like differential rotation, we suggest differential rotation values of Kepler-210 that are similar to or smaller than that of the Sun. Finally, we estimate spot life times between 60 days and 90 days, taking into consideration the evolution of the total covered stellar surface computed from our model.