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Astron. Astrophys. 354, 909-914 (2000)

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Multicolour high-speed photometry and [FORMULA] spectroscopy of XY UMa

D. Kjurkchieva 1, D. Marchev 1 and W. Ogloza 2,3

1 Department of Physics, Shoumen University, 9700 Shoumen, Bulgaria
2 N.Copernicus Astronomical Center, Polish Academy of Sciences, ul.Bartycka 18, 00-716 Warszawa, Poland
3 Mt. Suhora Observatory, Cracow Pedagogical University, ul.Podchorazych 2, 30-084 Cracow, Poland

Received 19 August 1998 / Accepted 20 July 1999


BVRI photometry and [FORMULA]-line spectroscopy of the short-period RS CVn-binary XY UMa are presented. The light curves as a whole as well as the two eclipse minima are asymmetric. The light level after the primary minimum is lower by about 0.04-0.05 mag than that after the secondary one. Two cool spots on the primary with sizes [FORMULA] and [FORMULA], temperatures 4630 and 4330 K at middle latitudes reproduced well the distortion curve in all colours. The observed [FORMULA] profile is quite wide and asymmetric at most the phases out of the eclipses. The radial velocity curve is sinusoidal with semiamplitude [FORMULA] km/s. The corresponding mass function of the system is 0.082[FORMULA]. The phase behaviour of the [FORMULA]-profile implies contribution of emission of the chromospheric regions above the photospheric spots.

Key words: publications, bibliography – book reviews – book reviews – stars: binaries: eclipsing – book reviews – stars: individual: XY UMa – book reviews – stars: luminosity function, mass function – book reviews – stars: starspots – Magnetohydrodynamics (MHD)

Send offprint requests to: W. Ogloza (ogloza@astro.as.wsp.krakow.pl)

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© European Southern Observatory (ESO) 2000

Online publication: February 25, 2000