K2 spots rotation in the helium star HD144941

Abstract

HD144941 is an evolved early-type metal-poor low-mass star with a hydrogen-poor surface. It is frequently associated with other intermediate helium-rich subdwarfs and extreme helium stars. Previous photometric studies have failed to detect any variability. New observations with the K2 mission show complex but periodic variations with a full amplitude of 4 parts per thousand. It is proposed that these are due to an inhomogeneous surface brightness distribution (spots) superimposed on a rotation period of 13.9+/-0.2 d. The cause of the surface inhomogeneity is not identified, although an oblique dipolar magnetic field origin is plausible.

Accepted by MNRAS

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• Electron Scattering Emission in the Light Curves of Stars with Centrifugal Magnetospheres
• TESS photometry of extreme helium stars PV Tel and V821 Cen
• Discovery of three magnetic helium-rich hot subdwarfs with SALT