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Paper: Eclipsing Binary Flux Units and the Distance Problem
Volume: 362, The Seventh Pacific Rim Conference on Stellar Astrophysics
Page: 3
Authors: Wilson, R.E.
Abstract: Requirements, strategies, error sources, and other facets of Direct Distance Estimation (DDE) for eclipsing binaries (EB) are traced in a review of light curve solutions in CGS physical units. Contrary to widespread opinion, tides and irradiance are not significant problems for EB distance measurement. Because the WD model has always produced intrinsically absolute fluxes (in user defined units), most of the computation is in place and a simple scaling relation can generate CGS light curves for given distance and interstellar extinction. Calibrations from standard magnitudes (U, B, V, etc.) to CGS flux are needed, but which of two published calibrations is applied has little importance. The problem of conversion from temperature observed (say spectroscopically) at particular [phase; inclination] to mean surface temperature was solved recently and is briefly outlined. DDE solutions are compared with traditional solutions in terms of input, free parameters, and output. The DDE program can switch between traditional (non-absolute) and CGS solutions. An Eclipsing Binary Temperature-distance theorem specifies circumstances under which temperatures of one or both stars and distance are derivable from multi-band light curve and radial velocity curve combinations. Realistic distance uncertainties and problems due to third stars are briefly covered. Results from a recent paper on the semi-detached binary RZ Cancri agree fully with Temperaturedistance theorem predictions. Solutions in the journals also can yield distances with the help of an abridged program that incorporates certain scaling relations, although with approximations due to use of some global quantities in place of local quantities. Such an abridged program runs in negligible time, so it can produce distances in great numbers from parameters in the literature.
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