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> Spiral galaxy M81 in Ursa Major

Spiral galaxy M81 in Ursa Major

author: Jim Misti/Novapix

reference: a-gax30-31008

Image Size 300 DPI: 33 * 22 cm

The M81 galaxy is about 12 million light-years away. The spiral arms, which wind all the way down into the nucleus, are made up of young, bluish, hot stars formed in the past few million years. They also host a population of stars formed in an episode of star formation that started about 600 million years ago. The galaxy's central bulge contains much older, redder stars. It is significantly larger than the Milky Way's bulge. A black hole of 70 million solar masses resides at the center of M81. The black hole is about 15 times the mass of the Milky Way's black hole.

Keywords for this photo:

2005 - ASTRONOMY - BLACK HOLE - GALAXY - M81 - NGC 3031 - Sb - SPIRAL GALAXY - STAR - STAR FORMATION - URSA MAJOR -