Persei, located in the constellation of
Perseus.
As a star exhausts its supply of hydrogen for fueling its internal nuclear reactions, it begins to swell in size as the surface layers become cool and reddened. Eventually, the star can become a red giant, many times larger than its size while in the hydrogen-burning phase of its life. If such a star happens to be a member of close binary system where two stars orbit about one another, it may be possible that the star becomes so distended that the surface layers feel a stronger gravitational attraction from the companion star than from the star to which they belong. In this case, the companion star is able to pull a stream of gas away from the giant star and onto itself. If the two stars are close enough, the stream actually impacts the companion star driving the temperatures in the gas up to millions of degrees Kelvin. After impact the material is reflected and begins to orbit the star forming an accretion disk.
Below is an image of the results of a two-dimensional hydrodynamic
simulation of just such a system,
Persei, located in the constellation of
Perseus.
In the image below, the red giant star is represented by the dark red oval shape, just to the right of center. The companion star, pulling the narrowing stream of gas toward it, is the blue disk in the center. The yellow and red colors around the companion star represent the intensity of the light emitted by the hot gas in the accretion disk orbiting the star.
If your web-browser is "Java Aware", you should notice two buttons below the image (Start and Stop). To begin the animation sequence, press the START button. Twenty images (4K each) will be loaded and animated with a one second pause between each frame. Otherwise, you can download the QuickTime Movie (1.7M) or MPEG Movie (1.2M) of the simulation.
The animation begins with the gas stream just beginning to leave the giant star. The stream free-falls toward the companion, strikes the surface and heats up, reflects and cools off as it falls into an orbiting accretion disk around the companion. Notice that most of the emission (dark red) in the accretion disk comes from cool, dense filaments.
Although a simple animation, this application of the Java programming language represents its usefulness in presenting the results of scientific research to an open community. Feel free to use the Java source code as a model for performing similar animations of your own.
For more information about this research, visit MORE INFORMATION.