The first Doppler imaging of the active binary prototype RS Canum Venaticorum

Xiang, Yue; Gu, Shenghong; Wolter, U.; Schmitt, J. H. M. M.; Cameron, A. Collier; Barnes, J. R.; Mittag, M.; Perdelwitz, V. and Kohl, S. (2020). The first Doppler imaging of the active binary prototype RS Canum Venaticorum. Monthly Notices of the Royal Astronomical Society, 492(3) pp. 3647–3656.

DOI: https://doi.org/10.1093/mnras/staa063

Abstract

We present the first Doppler images of the prototypical active binary star RS Canum Venaticorum, derived from high-resolution spectra observed in 2004, 2016 and 2017, using three different telescopes and observing sites. We apply the least-squares deconvolution technique to all observed spectra to obtain high signal-to-noise line profiles, which are used to derive the surface images of the active K-type component. Our images show a complex spot pattern on the K star, distributed widely in longitude. All star-spots revealed by our Doppler images are located below a latitude of about 70°. In accordance with previous light-curve modelling studies, we find no indication of a polar spot on the K star. Using Doppler images derived from two consecutive rotational cycles, we estimate a surface differential rotation rate of ΔΩ = −0.039 ± 0.003 rad d⁻¹ and α = ΔΩ/Ωeq = −0.030 ± 0.002 for the K star. Given the limited phase coverage during those two rotations, the uncertainty of our differential rotation estimate is presumably higher.