Separation of high resolution spectra of the multiple star system UX Ari ^*

Institute of Theoretical Astrophysics, PO Box 1029, Blindern, 0315 Oslo, Norway

Corresponding author: V. Aarum Ulvås, v.a.ulvas@astro.uio.no

Received: 29 November 2002
Accepted: 7 January 2003

Abstract

This paper presents a technique for separation of individual components in composite stellar spectra. The technique is based on a comparison of residual depths of the component spectral lines to residual depths of the corresponding spectral lines of a single star of the same spectral class. We apply the technique to high resolution spectra of the RS CVn system UX Ari, where the spectral lines from all three components are well resolved. The deduced variations in the relative flux of the primary component agree well with simultaneously obtained photometric observations of UX Ari. The starspots causing the light curve variations and the facular areas causing the chromospheric emission seem to be separated by about in longitude on the surface of the primary component. We also find that the secondary component of UX Ari is subject to some chromospheric activity. Finally, some fundamental parameters of the third star in the spectrum are derived and discussed.