Young stars and star formation in normal irregular galaxies.

Star formation in irregular galaxies is examined. The characteristics of some individual stars in the irregular galaxies are described. A range of sizes of star-forming regions are detected in irregular galaxies; the factors which limit the size of a star-forming region and the cloud formation processes are analyzed. Young and old star are observed in the star-forming regions of irregulars and the major star formation centers in irregulars move around the galaxy with time in a stochastic manner. The star formation rates for irregulars range from 5 x 10 to the -9th to 3 x 10 to the -10th solar mass/yr per sq pc for high surface brightness irregulars to 10 to the -11th solar mass/yr per sq pc for dwarf irregulars. It is noted that the gas supply, color, total stellar mass and luminosity, metallicity, and infrared luminosity data correlate with constant star formation rates and normal initial mass functions.