Realization of Accurate Close-Binary Light Curves: Application to MR Cygni

Abstract

A general procedure for computing monochromatic light curves of close eclipsing-binary systems is presented, with allowance for rotational and tidal distortion, the reflection effect, limb darkening, and gravity darkening. All basic techniques used to compute light curves are specified. Solution of the inverse problem (finding the elements from observations) is accomplished by differential corrections, and probable errors are obtained for all adjustable parameters. No rectification of any kind is used or needed. Because of the basic flexibility of the scheme, present limitations (e.g., synchronous rotation only, black- body physics) may be improved upon with reasonable convenience, as time permits. The procedure has been applied to B and V observations of MR Cyg, and the results of the differential corrections adjustments are given. With the use of available spectroscopic observations and model-atmosphere results by Mihalas, the components are placed in the H-R diagram. Although the primary seems to be on the main sequence, the secondary is found to be above the main sequence an observation which suggests that the secondary may still be in the gravitational-con traction phase.