Since variable stars are the once whose luminosity change according to our perception and all binary stars must go through eclipsing, Can we say that all binary stars are also variable stars?
1 Answer
The answer is no, for the following reasons.
First of all, the term "variable star" has a fairly specific meaning in the astrophysics realm: it customarily refers to a class of stars which have variability of their brightness, which can be cyclic (as for instance in the cepheid class of variable stars).
Second, not every binary pair is aligned in such a manner as to go through eclipse cycles when viewed from earth; in fact, very few binary pairs are aligned that way.
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$\begingroup$ Variable stars do not necessarily have to be cyclic in their variability (though quite a few are). Also, the "variability" is in their brightness, full stop, which does not have to have a "thermal" origin. $\endgroup$ Oct 24, 2018 at 9:33
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