EDP Sciences
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Volume 402, Number 2, May I 2003
Page(s) 509 - 530
Section Galactic structure and dynamics
DOI http://dx.doi.org/10.1051/0004-6361:20030021

A&A 402, 509-530 (2003)
DOI: 10.1051/0004-6361:20030021

Eclipsing binaries in the Magellanic Clouds

uvby CCD light curves and photometric analyses for HV 982 (LMC), HV 12578 (LMC), HV 1433 (SMC), and HV 11284 (SMC)
J. V. Clausen1, J. Storm2, S. S. Larsen1, 3 and A. Giménez4, 5

1  Niels Bohr Institute for Astronomy, Physics and Geophysics, Astronomical Observatory, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
    e-mail: jvc@astro.ku.dk
2  Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
    e-mail: jstorm@aip.de
3  UC Observatories/Lick Observatory, University of California, Santa Cruz, CA 95064, USA
    e-mail: soeren@ucolick.org
4  Laboratorio de Astrofísica Espacial y Física Fundamental INTA, Estacion de Villafranca del Castillo, Apdo. 50727, 28080 Madrid, Spain
5  Research and Scientific Support Department, ESA, ESTEC, Postbus 299, 2200 AG Noordwijk, The Netherlands
    e-mail: agimenez@rssd.esa.int

(Received 30 August 2002 / Accepted 16 December 2002 )

We present new accurate CCD uvby light curves for the LMC eclipsing binaries HV 982 and HV 12578, and for the SMC systems HV 1433 and HV 11284 obtained at the Danish 1.5 m telescope at ESO, La Silla. The light curves were derived from DoPHOT photometry, and typical accuracies are between 0.007 and 0.012 mag per point. Standard uvby indices have also been established for each binary, primarily for determination of interstellar reddening and absorption. For HV 982 and HV 12578, accurate photometric elements have been established. Both systems consist of two detached components of comparable sizes in an eccentric orbit. Adopting the spectroscopic elements given by Fitzpatrick et al. (2002) for HV 982, we derive absolute dimensions of its components which agree well with their results. A distance modulus of $V_0-M_V = 18.63 \pm 0.08$ is obtained, corresponding to a distance of $53.2 \pm 2.0$ kpc, which is in formal agreement with (although slightly larger than) their determination. HV 1433 and HV 11284 both consist of two rather close, deformed and quite different stars. As the mass ratios between the components (and their rotation rates) are not known, definitive photometric elements can not yet be obtained, but we present a sample of possible photometric solutions. In a series of forthcoming papers we will combine our uvby observations with high-dispersion spectra from the UVES spectrograph on the ESO Very Large Telescope (VLT) and present absolute dimensions, chemical abundances and distances for selected LMC and SMC systems, including HV 12578 and refined results for HV 982.

Key words: cosmology: distance scale -- galaxies: magellanic clouds -- stars: fundamental parameters -- stars: binaries: close -- stars: binaries: eclipsing -- techniques: photometric

Offprint request: J. V. Clausen, jvc@astro.ku.dk

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