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Astron. Astrophys. 347, 932-936 (1999)

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The long-period RS Canum Venaticorum binary IM Pegasi

I. Orbital and stellar parameters *

S.V. Berdyugina, I. Ilyin and I. Tuominen

Astronomy Division, University of Oulu, P.O. Box 3000, FIN-90401 Oulu, Finland

Received 30 April 1999 / Accepted 21 May 1999


New high-resolution and high signal-to-noise ratio spectroscopic observations carried out in 1996-1997 are analysed. A total of 85 new high quality radial velocity measurements are used for determining the new orbital parameters: [FORMULA]=HJD2450342.883+24.64880E , e=0.0, [FORMULA]=-14.09 km s-1, K1=34.39 km s-1. A model atmosphere analysis of the averaged spectrum of the star has yielded a self-consistent set of fundamental parameters of the primary component: [FORMULA]=4450 K, log g =2.4, [M/H]=0.0, [FORMULA]=1.6 km s-1, v sini =26.5 km s-1. The primary is found to be a typical K2 III giant with the mass of about 1.5 [FORMULA] which has undergone the first convective mixing on the Red Giant Branch ([C/H]=-0.32, [N/H]=0.30, C/N=1.15). The unspotted V magnitude of the star of 5[FORMULA]55 is estimated from the observed variations of the TiO band and quasi-simultaneous photometry. Combining all parameters, the radius and inclination of the primary as well as a probable spectral class of the secondary are estimated.

Key words: stars: abundances – stars: activity – stars: binaries: spectroscopic – stars: fundamental parameters – stars: individual: IM Peg – stars: late-type

* based on observations collected at the 2.6 m telescope of the Crimean Astrophysical Observatory, Ukraine and the Nordic Optical Telescope (NOT), La Palma, Spain

Send offprint requests to: S.V. Berdyugina (sveta@ukko.oulu.fi)

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© European Southern Observatory (ESO) 1999

Online publication: June 6, 1999