The Alpha Centauri binary system |
|
Alpha Centauri A, and B, are roughly
the size and age of the Sun. A has a similar surface temperature.
The two stars orbit their mutual center of mass at 24 AU, with
a period of 80 years. The red dwarf Proxima Centauri is
thought to be of the same age. It orbits ~13,000 AU from the
close binary pair with a period that is thought to be close to
5x105
years. 
With only 150 times the mass of Jupiter, and 1.5 times the diameter, tiny Proxima Centauri is just hot enough to fuse hydrogen to helium. It is only just big enough to be a star. Slow burning and long lived, Proxima Centauri will be orbiting the gallactic center long after the Sun has gone. |