What is a starburst galaxy?

Answer: Despite the name, a starburst galaxy has nothing to do with fruit-flavored candy. A starburst galaxy is one which is undergoing a high rate of star formation, often ten times what is seen in our own Milky Way galaxy. Many astronomers suspect that these galaxies have collided with other galaxies. The disruption of two vast collections of stars interacting with each other triggers shock waves that compress gas clouds enough to form new stars. These hot young stars often have violent winds, and the ensemble of such winds produces a “superwind” that blasts material out of these galaxies. This superwind also triggers even more star formation.

The starburst phase of a galaxy is short-lived in astronomical terms, perhaps only tens of millions of years. The rapid star formation uses up so much of the interstellar gas in the galaxy that little is left to form more stars. During this wild outburst, however, these starburst galaxies provide a chance for astronomers to study stellar evolution in action.

The Hubble Space Telescope NASA and ESA teams recently released a dramatic new picture of a famous starburst galaxy, M82, sometimes called the Cigar Galaxy. You can see it at:
http://www.esa.int/esaCP/SEMEQ8OFGLE_index_0.html

Starburst galaxies are also bright X-ray and infrared sources. Here are links for more information about these powerful sources:
http://chandra.harvard.edu/xray_sources/starburst.html

http://coolcosmos.ipac.caltech.edu//cosmic_classroom/
multiwavelength_astronomy/multiwavelength_museum/m82.html

This week's question comes from Dr. Dave Thompson. Dr. Thompson is an astrophysicist who studies gamma rays in the Exploration of the Universe Division. He helped build, test, and analyze data from EGRET on the Compton Gamma Ray Observatory, and he is now helping build part of the Gamma Ray Large Area Space Telescope (GLAST), scheduled for launch in 2007. His particular scientific interest is gamma-ray pulsars.