H observations of the star FK Com

Department of Physics, Shoumen University, 9700 Shoumen, Bulgaria e-mail: [d.kyurkchieva;d.marchev]@shu-bg.net

Received: 14 June 2004
Accepted: 9 December 2004

Abstract

High-resolution spectroscopic observations around the H_α line of FK Com are presented. The analysis of the spectra reveals that: (a) the intensity of the R peak of the mean H_α profile is larger than that of the V peak; (b) the intensities of the V and R emission peaks changes almost in anti-phase; (c) the ratio varies in phase with V; (d) the total H_α emission has a maximum at phase 0.75. The similarity of the H_α profile of FK Com with those of the disk-like stars leads us to the conclusion that its broad two-peaked emission H_α line originates from an extended disk. It is supposed that the disk produces the mean H_α line. The variability of the H_α profile is explained by the presence of additional sources of absorption and emission at diametrically opposite regions of the disk. The asymmetry of the mean H_α profile requires the disk to be half-illuminated. It is supposed that a source of illumination is a low-mass hot secondary orbiting the disk. A model of the H_α emitting configuration of FK Com is proposed.