H observations of the star FK Com
Department of Physics, Shoumen University, 9700 Shoumen, Bulgaria e-mail: [d.kyurkchieva;d.marchev]@shu-bg.net
Accepted: 9 December 2004
High-resolution spectroscopic observations around the Hα line of FK Com are presented. The analysis of the spectra reveals that: (a) the intensity of the R peak of the mean Hα 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 Hα emission has a maximum at phase 0.75. The similarity of the Hα profile of FK Com with those of the disk-like stars leads us to the conclusion that its broad two-peaked emission Hα line originates from an extended disk. It is supposed that the disk produces the mean Hα line. The variability of the Hα 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 Hα 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 Hα emitting configuration of FK Com is proposed.
Key words: stars: activity / stars: binaries: spectroscopic / stars: chromospheres / stars: individual: FK Com
© ESO, 2005