Introduction

Eclipsing binary stars are just one several types of variable stars. These stars appear as a single point of light to an observer, but based on its brightness variation and spectroscopic observations we can say for certain that the single point of light is actually two stars in close orbit around one another. The variations in light intensity from eclipsing binary stars is caused by one star passing in front of the other relative to an observer. If we assume that the stars are spherical and that they have circular orbits, then we can easily approximate how the light varies as a function of time for eclipsing binary stars.

Some eclipsing binaries

HS0705+6700 known also as V470 Cam, is a short period (0.0956466 days = 2h 17m 43.866s) detached binary system consisting of a blue subdwarf helium burning star (sdB) and a dwarf M type main sequence star.  Transit time variations suggest there may be a third body present, possibly a brown dwarf, and potemtislly a fourth body.  Both the third and fourth bodies need to be varified.  A table of known minimum can be found here (note after opening this link click on the Excel icon in bottom right hand corner) and references to this binary system here.

TW CrB

General references