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          Institute: MPI für Astrophysik     Collection: Cosmology     Display Documents

ID: 12189.0, MPI für Astrophysik / Cosmology
The MACHO project Large Magellanic Cloud variable star inventory. XII. Three Cepheid variables in eclipsing binaries
Authors:Alcock, C.; Allsman, R. A.; Alves, D. R.; Becker, A. C.; Bennett, D. P.; Cook, K. H.; Drake, A. J.; Freeman, K. C.; Griest, K.; Hawley, S. L.; Keller, S.; Lehner, M. J.; Lepischak, D.; Marshall, S. L.; Minniti, D.; Nelson, C. A.; Peterson, B. A.; Popowski, P.; Pratt, M. R.; Quinn, P. J.; Rodgers, A. W.; Suntzeff, N.; Sutherland, W.; Vandehei, T.; Welch, D. L.
Date of Publication (YYYY-MM-DD):2002
Title of Journal:The Astrophysical Journal
Journal Abbrev.:Astrophys. J.
Issue / Number:1
Start Page:338
End Page:350
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:We present a method for solving the light curve of an eclipsing binary system that 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 6.6454.5, 78.6338.24, and 81.8997.87. A best-fit value is obtained for each systems 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 Virginis 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.
Free Keywords:binaries : eclipsing; Cepheids; Magellanic Clouds; stars : AGB and post-AGB; stars : oscillations
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astrophysik
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