Differential rotation on the young solar analogue V889 Herculis

TL;DR

This study uses Doppler Imaging to map the surface of the young Sun-like star V889 Herculis, revealing weak differential rotation and surface features, contributing to understanding stellar rotation dynamics.

Contribution

First detailed Doppler imaging of V889 Herculis's surface features and measurement of its weak differential rotation, comparing results with previous studies and theoretical models.

Findings

Detected asymmetric polar cap and low-latitude features.

Measured weak differential rotation with deltaOmega/Omega~0.009.

Results align with some prior studies and theoretical expectations.

Abstract

V889 Herculis is one of the brightest single early-G type stars, a young Sun, that is rotating fast enough (P_rot =1.337 days) for mapping its surface by Doppler Imaging. The 10 FOCES spectra collected between 13-16 Aug 2006 at Calar Alto Observatory allowed us to reconstruct one single Doppler image for two mapping lines. The FeI-6411 and CaI-6439 maps, in a good agreement, revealed an asymmetric polar cap and several weaker features at lower latitudes. Applying the sheared-image method with our Doppler reconstruction we perform an investigation to detect surface differential rotation (DR). The resulting DR parameter, deltaOmega/Omega~0.009 of solar type, is compared to previous studies which reported either much stronger shear or comparably weak DR, or just preferred rigid rotation. Theoretical aspects are also considered and discussed.