Achernar

Spectral class: B3 Vpe
Galactic coordinates:

l 290

b -58.95

Plane dist 73.15

A type Be star, also known as Alpha Eridani. Achernar is a bright blue-white main sequence star, and one of the least spherical stars in the Milky Way. It spins so rapidly that its equatorial diameter is more than 50% greater than its polar diameter. A fast-spinning hot star, it is also very young with no more than a few hundred million years, like Regulus A.

The star is located 144 light-years from Sol system, the seat of government of the United Commonwealth of Planets. The name of the star comes from the human آخر النهر (ākhir an-nahr), or "river's end", and the star has two planetary companions Järvenpää and Joensuu, names which also reflect the meaning of the star's title.

Ejecting mass at a high rate, Achernar's high spin velocity of 225 to 300 kilometers per second has helped to turn it into a type Be star, which has an expanding circumstellar envelope (CSE) of gas circulating around its equator when its CSE is enlarged by mass ejections. As a very young high-mass star, Achernar is a fast rotator with a rotational period of hours and a substantial magnetic field around one kG.

Achernar is also a member of a peculiar class of Lambda Eridani-type stars that show small but very regular periodic light variations (with a period of 1.26 days) that may be caused by actual complex pulsations or by rotation and dark "starspots". Although Achernar is a massive star, it is still young enough to be fusing hydrogen into helium in its core and may be small enough to evolve off the sequence as a massive white dwarf like Sirius B.