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

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5. Summary

From new high-resolution and high S/N spectra of IM Peg, the following results have been obtained:

1. New orbital parameters have been determined, the ephemeris being improved: [FORMULA] = 2450342.883 + 24.64880E , e=0.0, [FORMULA]= -14.09 km s-1, K1=34.39 km s-1.

2. A model atmosphere analysis of the spectrum of IM Peg 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. This corresponds to a K2 III star. The observed abundances of the carbon and nitrogen suggest that the primary has undergone the first convective mixing in its atmosphere on the Red Giant Branch.

3. An unspotted V magnitude of 5[FORMULA]55 was estimated from the observed variation of the TiO band and quasi-simultaneous photometry. The absolute magnitude of the star of 0[FORMULA]62 is found.

4. By combining all parameters, the radius R1 = 13.3[FORMULA]0.6 [FORMULA] and the inclination 65o[FORMULA]80o of the primary have been estimated with the assumption that its rotational axis is perpendicular to the orbital plane.

5. The unseen secondary is believed to be a K0 main sequence star with a mass of about 0.8[FORMULA]0.1 [FORMULA].

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© European Southern Observatory (ESO) 1999

Online publication: June 6, 1999