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

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

Abstract

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: =HJD2450342.883+24.64880E , e=0.0, =-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: =4450 K, log g =2.4, [M/H]=0.0, =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 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 555 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)

SIMBAD Objects

Contents

• 1. Introduction
• 2. Observations and data reduction
• 3. Parameters of the orbit
• 4. Stellar parameters
  • 4.1. T_eff, log g , and metallicity
  • 4.2. The CNO abundances
  • 4.3. Fundamental parameters of the components
• 5. Summary
• Acknowledgements
• References

© European Southern Observatory (ESO) 1999

Online publication: June 6, 1999
helpdesk.link@springer.de