The MACHO Project LMC Variable Star Inventory: XII. Three Cepheid Variables in Eclipsing Binaries

Abstract

We present a method for solving the lightcurve of an eclipsing binary system which contains a Cepheid variable as one of its components as well as the solutions for three eclipsing Cepheids in the Large Magellanic Cloud (LMC). A geometric model is constructed in which the component stars are assumed to be spherical and on circular orbits. The emergent system flux is computed as a function of time, with the intrinsic variations in temperature and radius of the Cepheid treated self-consistently. Fitting the adopted model to photometric observations, incorporating data from multiple bandpasses, yields a single parameter set best describing the system. This method is applied to three eclipsing Cepheid systems from the MACHO Project LMC database: MACHO ID's 6.6454.5, 78.6338.24 and 81.8997.87. A best-fit value is obtained for each system's orbital period and inclination and for the relative radius, color and limb-darkening coefficients of each star. Pulsation periods and parameterizations of the intrinsic color variations of the Cepheids are also obtained and the amplitude of the radial pulsation of each Cepheid is measured directly. The system 6.6454.5 is found to contain a 4.97-day Cepheid, which cannot be definitely classified as Type I or Type II, with an unexpectedly brighter companion. The system 78.6338.24 consists of a 17.7-day, W Vir Class Type II Cepheid with a smaller, dimmer companion. The system 81.8997.87 contains an intermediate-mass, 2.03-day overtone Cepheid with a dimmer, red giant secondary.

35 pages, 14 tables, 6 figures, web address for photometry included, minor changes to abstract and author list, comments and references added to sections 3 and 5, accepted for publication in ApJ, direct scientific correspondence to D. Lepischak and D.L. Welch

References in corpus (1)

• Period - magnitude relationships in BVIJHK-Bands for fundamental mode and first overtone Cepheids

Cited by in corpus (21)

• The Catalina Surveys Periodic Variable Star Catalog
• Accurate dynamical mass determination of a classical Cepheid in an eclipsing binary system
• Optically Visible Post-AGB Stars, Post-RGB Stars and Young Stellar Objects in the Large Magellanic Cloud
• Physical parameters and the projection factor of the classical Cepheid in the binary system OGLE-LMC-CEP-0227
• Multiplicity of Galactic Cepheids and RR Lyrae stars from Gaia DR2 - I. Binarity from proper motion anomaly
• Mass and p-factor of the type II Cepheid OGLE-LMC-T2CEP-098 in a binary system
• Multiplicity of Galactic Cepheids and RR Lyrae stars from Gaia DR2 -- II. Resolved common proper motion pairs
• Supervised detection of anomalous light-curves in massive astronomical catalogs
• The Araucaria Project: High-precision Cepheid astrophysics from the analysis of variables in double-lined eclipsing binaries
• The Araucaria Project: The First-Overtone Classical Cepheid in the Eclipsing System OGLE-LMC-CEP-2532
• The Araucaria Project: A study of the classical Cepheid in the eclipsing binary system OGLE LMC562.05.9009 in the Large Magellanic Cloud
• Luminosities and infrared excess in Type II and anomalous Cepheids in the Large and Small Magellanic Clouds
• Binarity among Cepheids in the Magellanic Clouds
• The Nature of the Companion to the Eclipsing Overtone Cepheid MACHO 81.8997.87
• In search of RR Lyrae type stars in eclipsing binary systems. OGLE052218.07-692827.4: an optical blend
• Cepheids with giant companions. II. Spectroscopic confirmation of nine new double-lined binary systems composed of two Cepheids
• TYC 1031 01262 1: The First Known Galactic Eclipsing Binary with a Type II Cepheid Component
• Leveraging pre-trained vision Transformers for multi-band photometric light curve classification
• The influential effect of blending, bump, changing period and eclipsing Cepheids on the Leavitt law
• Eclipsing Binaries: Tools for Calibrating the Extragalactic Distance Scale
• A large-scale survey for variable stars in M33