Coma Berenices (dwarf galaxy)

The Coma Berenices dwarf galaxy short - Com is also a dwarf spheroidal galaxy in the constellation Coma Berenices. It was discovered in 2006 in imaging survey of the Sloan Digital Sky Survey.

Properties

Sizes

The galaxy is located at a distance of about 44 kpc to our solar system and away from our sun at a speed of about 98 km / s It has an ellipsoidal shape with a Achsverhältnisse of about 5:3 and a half-light radius of 70 pc.

Luminosity

Com is one of the smallest and faintest satellite galaxies of the Milky Way (only Segue 1, Segue 2, boat II and Willman 1 are fainter ). The integral luminosity corresponds to an absolute magnitude of MV = -4.1 m in about the 3,700 times the sun, which is less than the brightness of the majority of globular clusters. Nevertheless, the dwarf galaxy has a total mass of about 1.2 million solar masses due to a high mass-luminosity ratio of 450. This implies a not untypical for this type of galaxy domination by dark matter.

Metallicity

The stellar population of the Coma Berenices - dwarf galaxy consists mainly of older stars, which emerged more than 12 billion years ago. The metallicity of this aging generation of stars is correspondingly low with [Fe / H] = -2.53 ± 0.45, which means that they sometimes less in heavy elements has approximately 350 than the sun.

The stars of this dwarf galaxy are thus probably the first stars ever to have formed in the universe. Currently holds this galaxy is no detectable star formation, the lower measurement limit of neutral hydrogen gas is 46 M ☉.

Origin

The Coma dwarf is located near the Sagittarius stream, which is composed of lost stars of the Sagittarius dwarf galaxy. This makes an earlier physical connection of these two galaxies probably.