(small galaxy with a few billion stars)
The term dwarf galaxy is used for galaxies much smaller
than the Milky Way, i.e.,
of a few billion stars at most, and as small as 100 parsecs
across. They can be any of the normal galaxy types, such as a
Often they are satellite galaxies.
Some more specific terms:
- blue compact dwarf galaxy - with young hot stars.
- ultra-compact dwarf galaxy - in the 100-parsec range.
- hobbit galaxy - small, faint dwarf galaxy.
Examples (in Local Group):
David Dunlap Observatory Catalog (DDO)
dwarf spheroidal galaxy (dSph)
hierarchical assembly of galaxies
I Zwicky 18 (I Zw 18)
Local Group (LG)
low-surface-brightness galaxy (LSB galaxy)
TiNy Titans (TNT)
Triangulum II (Tri II)
ultra-faint dwarf galaxy (UFD)