An Etymological Dictionary of Astronomy and Astrophysics

An small → irregular galaxy undergoing → violent star formation activity. These objects appear blue by reason of containing clusters of hot, → massive stars
which ionize the surrounding interstellar gas. They are chemically unevolved since their → metallicity is only 1/3 to 1/30 of the solar value. Same as → H II galaxy.

See also: → blue; → compact; → dwarf; → galaxy.