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Eclipsing Binary Light Curves

Eclipsing Binary Light Curves

An X-ray binary is a special binary system where one of the stars is a normal star but the other star is an odd star, an X-ray emitting neutron star or white dwarf or black hole. By looking at the X-ray emission from the system, which comes mostly from the X-ray star, we can learn the size of the stars in the system.

Below, there is a representation of a light curve as it would appear from plotting data from eclipsing binaries. Above the light curve is a diagram showing where the two stars in the system are relative to each other (as seen by the observer). Notice how the "brightness" or "magnitude" changes as the smaller star is behind, next to, and in front of the larger star. The X-ray intensity of the system is greatest when both stars are completely visible, and least when the X-ray emitting star is eclipsed by the central star, which blocks out the X-rays from the smaller star.

plot of eclipsing binary
light curve

animated eclipsing binary

Now that you've learned how to interpret binary light curves, you'll have a chance to practice identifying the parts of an X-ray light curve.

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A service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA/GSFC

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