Regulus, The Little King of Leo

The brightest Star in the constellation Leo is Regulus, and it is also one of the brightest stars in the night sky, with only 21 stars brighter.  Regulus is strictly speaking a star system, composed of Regulus A, the source of its brightness and a white dwarf companion that has not yet been observed, and to other stars too dim to be easily visible.  Also known as Alpha Leonis for its primary position in the constellation, the name Regulus means ‘little king’ or ’kinglet’ and also occasionally prince.  Regulus derives from the Latin word rex, regis, taking the diminutive form.

Regulus A is a large, hot star, about 4 times as wide as our sun but much brighter and with over 1000 times the energy output.  Regulus A is also spinning about 1000 times faster on its axis and shooting through space like a bullet!  Scientists are unclear what the source of this energy and movement is.

Image of the constellation Leo from Wikimedia commons, in the public domain.

Constellation map by Torsten Bronger, used with permission under Creative Commons 3.0 license.

Computer generated image of Regulus A by Chandra, used with permission.