Rotation--differential rotation relationships for late-type single and binary stars from Doppler imaging

TL;DR

This study investigates how surface differential rotation relates to rotation period in late-type stars, revealing distinct patterns for single stars versus close binary systems, with tidal forces influencing the differential rotation in binaries.

Contribution

It provides the first comparative analysis of differential rotation in single and binary late-type stars using Doppler imaging, highlighting the impact of tidal forces.

Findings

Single stars show increasing differential rotation with longer rotation periods.

Binary stars exhibit weak or no dependence of differential rotation on rotation period.

Tidal forces in binary systems may regulate differential rotation patterns.

Abstract

From our sample of spotted late-type stars showing surface differential rotation we find that the relationship between the rotation period and the surface shear coefficient $\alpha=\Delta\Omega/\Omega_{\rm eq}$ is significantly different for single stars compared to members in close binaries. Single stars follow a general trend that $\alpha$ increases with the rotation period. However, differential rotation of stars in close binary systems shows much weaker dependence on the rotation, if any, suggesting that in such systems tidal forces operate as a controlling mechanism of differential rotation.