C

Abstract

We present a multi-epoch time-resolved high-resolution optical spectroscopy study of the short-period (Porb = 11.2 hr) eclipsing M0V+M5V RS CVn binary V405 Andromeda. By means of indirect imaging techniques, namely Doppler imaging, we study the surface activity features of the M0V component of the system. A modified version of a Doppler imaging code, which takes into account the tidal distortion of the surface of the star, is applied to the multi-epoch data set in order to provide indirect images of the stellar surface. The multi-epoch surface brightness distributions show a low intensity “belt” of spots at latitudes ±40◦ and a noticeable absence of high latitude features or polar spots on the primary star of V405 Andromeda. They also reveal slow evolution of the spot distribution over ∼4 yr. An entropy landscape procedure is used in order to find the set of binary parameters that lead to the smoothest surface brightness distributions. As a result, we find M1 = 0.51 ± 0.03 M , M2 = 0.21 ± 0.01 M , R1 = 0.71 ± 0.01 R , and an inclination i = 65◦ ± 1◦. The resulting systemic velocity is distinct for different epochs, raising the possibility of the existence of a third body in the system.