Stellar system
A stellar system is a group of planets, comets and asteroids, orbiting around a star, or several stars, just like Planet Earth, and its siblings, orbit Sol, our sun, the center of the Solar system.
In popular culture writers sometimes incorrectly refer to "other Solar systems", when there is only one Solar system, the objects orbiting around Sol.
Binary systems, and systems with more than two stars
[edit | edit source]The Solar system orbits a single star, Sol, but binary systems, with two stars, are common.
The stars in some binary systems have orbits so close any planets and comets in those systems would have to orbit the barycentre of the pair of stars.
The Alpha Centauri system
[edit | edit source]There are three stars in the nearby Alpha Centauri system. Alpha Centauri A and Alpha Centauri B are yellow dwarf stars, similar to Sol, with eccentric orbits that average about 11 astronomical units from one another, and they take 79.1 years to orbit one another. Alpha Centauri C is a dim red dwarf star, found 13,000 astronomical units from its siblings. It takes 550,000 years to orbit the inner pair.