NGC 2915 [SEP] constellation
NGC 2915
NGC 2915 is a blue dwarf galaxy located 12 million light-years away in the southern constellation Chamaeleon, right on the edge of the Local Group. The optical galaxy corresponds to the core of a much larger spiral galaxy traced by radio observation of neutral hydrogen.
The galaxy has a short central bar, much like the Milky Way and very extended spiral arms.
The reason for the spiral arms and majority of the galaxy's disk to be still neutral hydrogen (as opposed to have formed stars)
periods, so the galaxies have time to cool and to build up matter to form new stars. As time passes, this star formation changes the shape of the galaxies.
Nearby examples include NGC 1705, NGC 2915, NGC 3353 and UGCA 281.
Ultra-compact dwarfs.
Ultra-compact dwarf galaxies (UCD) are a class of very compact galaxies with very high stellar densities,
discovered in the 2000s.
They are thought to be on the order of 200 light years across, containing about