ECLIPSING BINARIES IN THE MACHO DATABASE: NEW PERIODS AND CLASSIFICATIONS FOR 3031 SYSTEMS IN THE LARGE MAGELLANIC CLOUD

摘要

Eclipsing binaries offer a unique opportunity to determine fundamental physical parameters of stars by using the constraints on the geometry of the systems. Here we present a reanalysis of publicly available two-color observations of about 6800 stars in the Large Magellanic Cloud obtained by the MACHO Project between 1992 and 2000 and classified as eclipsing variables. Of these, fewer than half are genuine eclipsing binaries. We determined new periods and classified the stars, 3031 in total, using the Fourier parameters of the phased light curves. The period distribution is clearly bimodal, reflecting separate groups of more massive blue main-sequence objects and low-mass red giants. The latter resemble contact binaries and obey a period-luminosity relation. Using evolutionary models, we identified foreground stars. The presented database has been cleaned of artifacts and misclassified variables, thus allowing searches for apsidal motion, tertiary components, pulsating stars in binary systems, and secular variations with timescales of several years.