EDP Sciences
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Volume 402, Number 3, May II 2003
First Science with the ODIN satellite
Page(s) 1043 - 1053
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361:20030024

A&A 402, 1043-1053 (2003)
DOI: 10.1051/0004-6361:20030024

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

V. Aarum Ulvås and O. Engvold

Institute of Theoretical Astrophysics, PO Box 1029, Blindern, 0315 Oslo, Norway
(Received 29 November 2002 / Accepted 7 January 2003)

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 $180^\circ$ 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.

Key words: techniques: spectroscopic -- stars: activity -- binaries: spectroscopic -- stars: imaging -- stars: individual: UX Ari -- starspots

Offprint request: V. Aarum Ulvås, v.a.ulvas@astro.uio.no

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