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Astron. Astrophys. 324, 137-154 (1997)


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Eclipsing binaries with candidate CP stars

I. Parameters of the systems HD 143654, HD 184035 and HD 185257 * **

P. North , M. Studer and M. Künzli

Institut d'Astronomie de l'Université de Lausanne, CH-1290 Chavannes-des-Bois, Switzerland

Received 6 November 1996 / Accepted 3 February 1997

Abstract

Lightcurves of three eclipsing binaries (HD 143654 = TV Nor, HD 184035 = HR 7422 and HD 185257 = HR 7464) in seven colours are analyzed and their photometric elements are given. Published radial velocities of two of them allow some constraints to be put on the masses of the components, while new radial velocities allow us to estimate the mass and absolute radius of each component of the system TV Nor. There seems to be no Ap star in this system, in spite of its EuCrSr classification in the Michigan catalogue. The position of each component of TV Nor in the HR diagram is in excellent agreement with stellar evolution models having [FORMULA] and an age [FORMULA] years.

There is an Am star in the system HD 185257, but no CP star in the system HD 184035 in spite of its sharp lines. The physical parameters of these two binaries could be determined, but less accurately and in a less fundamental way than those of TV Nor. They match theoretical isochrones and evolutionary tracks in a satisfactory way for HD 185257, but the measured mass function of HD 184035 seems slightly too small compared with the expected theoretical masses.

More data, both photometric and spectroscopic, would be useful, especially for the last two systems.

Key words: stars: binaries: eclipsing – stars: binaries: spectroscopic – stars: chemically peculiar – stars: early-type – stars: fundamental parameters – stars: individual: HD 143654, HD 184035, HD 185257

* Based on observations collected at the European Southern Observatory, La Silla, Chile
** Tables 1, 2 and 3 are available only in electronic form at the CDS via anonymous ftp 130.79.128.5

Send offprint requests to: P. North

© European Southern Observatory (ESO) 1997

Online publication: May 26, 1998

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