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Astron. Astrophys. 326, 1044-1054 (1997)

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Photometric versus empirical surface gravities
of eclipsing binaries *

C. Jordi 1, I. Ribas 1, J. Torra 1 and A. Giménez 2

1 Departament d'Astronomia i Meteorologia, Universitat de Barcelona, Avda. Diagonal 647, E-08028 Barcelona, Spain
2 LAEFF (INTA-CSIC), Apartado 50727, E-28080 Madrid, Spain

Received 18 March 1997 / Accepted 20 May 1997

Abstract

Systematic differences in photometric stellar surface gravity determination are studied by means of the comparison with empirical values derived from detached double-lined eclipsing binaries. Photometric gravities were computed using Moon & Dworetsky (1985) grids based on Kurucz (1979) atmosphere models, and empirical gravities were taken from Andersen (1991). Individual Strömgren colours and [FORMULA] indices of each component of the binary system have to be taken into account to correctly analyze the observed differences. A compilation of data on a sample containing 30 detached double-lined eclipsing binaries with accurate ([FORMULA]  1-2%) determination of mass and radius and available [FORMULA] photometric data is also presented.

Correction of the differences in terms of [FORMULA] and [FORMULA] for the range 11000 K [FORMULA] 20000 K reduces the mean residuals from 0.13 dex to 0.07 dex. For the range 7000 K [FORMULA] 8500 K, the consideration of metallicity effects by means of [FORMULA] index improves the accuracy from 0.20 dex to 0.09 dex.

Key words: stars: fundamental parameters - stars: binaries: eclipsing - stars: early-type - stars: late-type

* Table 5 is also available in electronic form from CDS via anonymous ftp at 130.79.128.5, and by e-mail request to C. Jordi at carme@facjn0.am.ub.es

Send offprint requests to: C. Jordi

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© European Southern Observatory (ESO) 1997

Online publication: April 8, 1998
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