Companion galaxies
Galaxy photometry
Elliptical galaxies
Primordial galaxies
High-redshift galaxies
Compact galaxies
Emission line galaxies
Giant galaxies
Post-starburst galaxies
Low surface brightness galaxies
Lyman-alpha galaxies
Quenched galaxies
Dwarf galaxies
Late-type galaxies
Protogalaxies
Quasar-galaxy pairs
Active galaxies
Early-type galaxies
Radio jets
Irregular galaxies
Double galaxies
Infrared excess galaxies
Lyman-break galaxies
Interacting galaxies
Disk galaxies
Starburst galaxies
High-velocity stars
Field galaxies
Galaxy classification systems
Galaxy spectroscopy
Galaxies
Generally, a large body of gas, dust, and stars held together by their mutual gravitational attraction and ranging in mass from about 10^6 to 10^13 M_sun. If a galaxy also contains dark matter its mass will be much larger. Galaxies are grouped into three main categories: spiral galaxies, elliptical galaxies, and irregular galaxies.
Galactic and extragalactic astronomy