NGC 2976

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NGC 2976 is a small, peculiar dwarf galaxy in the northern constellation Ursa Major. It belongs to the M81 Group and lies about 11.6 million light-years from Earth, roughly 190,000 light-years from the large galaxy M81. It was discovered by William Herschel in 1801.

Appearance and structure: The galaxy looks like a pure disk with no obvious bulge or clear spiral arms, though some classifications describe tightly wound or loosely wound arm features in the gas. It is tilted about 65 degrees to our line of sight. The inner disk may have a central bar with larger-scale gas patterns, and dark lanes and bright star clusters are visible.

Star formation and gas: There are two strong star-forming regions (H II regions) on opposite sides of the galaxy. The overall star formation rate is modest, about 0.2 solar masses per year. The outer disk has formed stars steadily over time, but the rate has declined over the last billion years, so the population now is dominated by older stars. Within roughly 3 kpc of the center, star formation has stayed steady.

Gas and environment: A cloud of neutral hydrogen about 27 kpc northeast of NGC 2976 (mass ~2.7×10^7 solar masses) may be pulling on the galaxy. There is evidence of tidal stripping, including an extended hydrogen tail, with the last significant interaction occurring about 1 billion years ago. The galaxy’s size is about 6 kiloparsecs across, and its apparent size is roughly 5.9 by 3.0 arcminutes.