Astronomy & Astrophysics

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Issue		A&A Volume 386, Number 2, May I 2002
Page(s)		548 - 557
Section		Formation, structure and evolution of stars
DOI		10.1051/0004-6361:20020239

A&A 386, 548-557 (2002)
DOI: 10.1051/0004-6361:20020239

Spectroscopic observations of the short-period, RS CVn-type star SV Cam

D. P. Kjurkchieva¹, D. V. Marchev¹ and S. Zola^{2, 3}

¹ Department of Physics, Shoumen University, 9700 Shoumen, Bulgaria and Isaac Newton Institute of Chile, Bulgarian Branch
e-mail: d.kyurkchieva@shu-bg.net;
e-mail: d.marchev@shu-bg.net
² Astronomical Observatory, Jagiellonian University, ul. Orla 171, 30-244 Cracow, Poland
³ Mt. Suhora Observatory of the Pedagogical University, ul. Podchorazych 2, 30-094 Cracow, Poland

(Received 25 September 2001 / Accepted 12 February 2002 )

Abstract
Spectroscopic observations of the eclipsing, short-period RS CVn-star SV Cam in the range Å, covering the whole orbital period are presented. The absorption profiles of the lines H $_{\alpha}$ and FeI 6678 are doubled out of the eclipses. The relative contribution of the secondary star is stronger in the FeI 6678 line than in H $_{\alpha}$ . We determined $K_{1}=123.1\pm1.2$ km s ^-1 and $K_{2}=207.6\pm1.8$ km s ^-1 by measurements of the Doppler shifts of these lines. The resulting masses of the components are: $M_{1}=1.47\pm0.06~M_{\odot}$ and $M_{2}=0.87\pm0.06~M_{\odot}$ . From the radial velocity solution and photometrically obtained relative stellar radii we determined the absolute radii of the components: $R_{1}=1.38\pm0.05~R_{\odot}$ and $R_{\rm 2}=0.94\pm0.06~R_{\odot}$ . The equatorial velocities $V_{\rm eq}^{\rm 1}=116$ km s ^-1 and $V_{\rm eq}^{\rm 2}=79$ km s ^-1 corresponding to the measured rotational broadenings of the investigated lines coincide with the velocities calculated from the obtained stellar radii. The phase behavior of both H $_{\alpha}$ and FeI 6678 profiles of the primary star shows the presence of two cool spots with maximum visibilities at phases 0.27 and 0.86. The analysis of the two lines in the middle of the primary eclipse allows us to illustrate the excess of the H $_{\alpha}$ emission of the secondary star. The parameters of the stellar components of SV Cam derived from our spectroscopy and photometry are in very good agreement. The final result of our investigation is that there are three sources of activity in SV Cam: local active regions (photospheric spots) on its primary component, enhanced chromospheric emission from the secondary star and some additional emission originating from circumstellar gas.

Key words: stars: activity -- binaries: eclipsing -- binaries: spectroscopic -- stars: chromospheres -- stars: individual: SV Cam -- stars: starspots

Offprint request: S. Zola, zola@astro1.as.wsp.krakow.pl

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