Eclipsing Binaries in the MACHO Database: New Periods and Classifications for 3031 Systems in the Large Magellanic Cloud

Eclipsing binaries offer a unique opportunity to determine fundamentalphysical parameters of stars using the constraints on the geometry of thesystems. Here we present a reanalysis of publicly available two-colorobservations of about 6800 stars in the Large Magellanic Cloud, obtained by theMACHO project between 1992 and 2000 and classified as eclipsing variable stars.Of these, less than half are genuine eclipsing binaries. We determined newperiods and classified the stars, 3031 in total, using the Fourier parametersof the phased light curves. The period distribution is clearly bimodal,reflecting refer to the separate groups of more massive blue main sequenceobjects and low mass red giants. The latter resemble contact binaries and obeya period-luminosity relation. Using evolutionary models, we identifiedforeground stars. The presented database has been cleaned of artifacts andmisclassified variables, thus allowing searches for apsidal motion, tertiarycomponents, pulsating stars in binary systems and secular variations withtime-scales of several years.Comment: 11 figures, 9 pages, accepted for publication in Ap