Dependence of stellar differential rotation on effective temperature and rotation: an analysis from starspot transit mapping

TL;DR

This study uses starspot transit mapping to analyze how stellar differential rotation varies with effective temperature and rotation period, revealing a strong link with rotation period and a weak link with temperature, aiding understanding of stellar evolution.

Contribution

First application of starspot transit mapping to measure differential rotation across multiple stars, establishing relationships with temperature and rotation period.

Findings

Significant negative correlation between rotational shear and rotation period.

Weak correlation between differential rotation and effective temperature.

Provides insights into stellar evolution and magnetic dynamo processes.

Abstract

Stellar rotation is crucial for studying stellar evolution since it provides information about age, angular momentum transfer, and magnetic fields of stars. In the case of the Sun, due to its proximity, detailed observation of sunspots at various latitudes and longitudes allows the precise estimate of the solar rotation period and its differential rotation. Here, we present for the first time an analysis of stellar differential rotation using starspot transit mapping as a means of detecting differential shear in solar-type and M stars. The aim of this study is to investigate the relationship between rotational shear, $\Delta\Omega$, with both the star's effective temperature ($T_{\text{eff}}$) and average rotation period ($P_{\text{r}}$). We present differential rotation profiles derived from previously collected spot transit mapping data for 13 slowly rotating stars ($P_{\text{rot}} \geq 4.5$ days), with spectral types ranging from M to F, which were observed by the Kepler and CoRoT satellites. Our findings reveal a significant negative correlation between rotational shear and the mean period of stellar rotation (correlation coefficient of -0.77), which may be an indicator of stellar age. On the other hand, a weak correlation was observed between differential rotation and the effective temperature of the stars. Overall, the study provides valuable insights into the complex relationship between stellar parameters and differential rotation, which may enhance our understanding of stellar evolution and magnetic dynamos.