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The Science: X-ray Binary Star Systems

Many objects in the sky emit X-rays. The x-rays originate from regions of gas that are at high temperatures. Astronomers are interested in how the gas gets this hot, and what happens when it does.

One common type of object that emits x-rays are binary star systems. These systems consist of two stars that orbit around each other. Sometimes, one star is a compact object, such as a black hole or neutron star. This compact object orbits close enough to the normal star that gas flows from the normal star to the compact star. As the gas gets close to the comapct star, the gas heats up and emits x-rays. The more gas there is, the more x-rays are emitted.

The following pages provide some useful background information.

In this lesson, you will examine data from the X-ray source GX301-2 taken by the RossiX-ray Timing Explorer ( GX301-2 is an X-ray binary system consisting of a supergiant blue star and a neutron star. In some X-ray binaries, the intensity of the X-rays varies regularly as the normal star moves in its orbit around the compact object. In this investigation you will explore these variations, find a period for the variations, and determine why the intensity of the X-rays varies.

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