Eta Leonis (η Leo, η Leonis) is a third-magnitude blue supergiant star in the constellation Leo, about away.
Eta Leonis is a blue supergiant with the stellar classification A0Ib. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.[1] Though its apparent magnitude is 3.5, making it a relatively dim star to the naked eye, it is nearly 20,000 times more luminous than the Sun, with an absolute magnitude of -5.60. The Hipparcos astrometric data has estimated the distance of Eta Leonis to be roughly 390 parsecs from Earth, or 1,270 light years away. It is believed to be in a blue loop phase.
Eta Leonis is apparently a multiple star system, but the number of components and their separation is uncertain.[2]