Leo A

Leo A (also known as Leo III ) is an irregular galaxy in the constellation of Leo. A member of the Local Group was discovered in 1942 by Fritz Zwicky.

Properties

Sizes

Leo A is located at a distance of about 690 kpc to our solar system and away from our sun at a speed of about 24 km / s It is relatively isolated from other galaxies of the Local Group. The mass can be about ( 8.0 ± 2.7 ) × 107 M ⊙ estimated with a share of at least 80 % of dark matter.

Age

Leo A is one of the most isolated galaxies of the Local Group and for a period of several billion years shows no signs of interaction or merger with other galaxies. The presence of RR Lyrae stars shows Leo A has a very old stellar population with an age of up to 10 billion years ago.

Composition

The neutral hydrogen of the galaxy shows a spatial extent corresponding to the optical size of the dwarf galaxy and compaction to a non-uniform ring. The galaxy does not rotate and the hydrogen gas moves in random piles around. The proportion of heavier elements is only one to two percent that of our sun, which indicates a much lower stellar evolution compared to our Milky Way. Leo A shows signs of increased star formation billions of years ago, but the current star formation rate is low. There are there four H II regions excited by short-lived star of spectral type O.