(binary star system detected by variations in magnitude)
An eclipsing binary is
a binary star system in which one star passes in front of the other,
detected by the reduction in observed light when that occurs,
much as a transiting planet is detected.
It is a type of variable star, with a variable type of E.
It is one of a number binary-star classes based upon how the
star is determined to be binary. Others:
A double-line detached eclipsing binary (DDEB)
is an eclipsing binary that is also a
double-line spectroscopic binary and a
detached binary (i.e., not in contact).
DDEBs offer extraordinary information about both companions because
the spectral lines reveal each companions' radial velocities,
the eclipses reveal the orbital period and establish that
the orbital inclination is roughly "edge on". From these, the
orbits and masses of the companions are determinable, a key
technique in the development of astrophysics, i.e., the development
and confirmation of theories of stars.