The most luminous galaxies in the universe are over a thousand times more powerful than our Milky Way...yet they are not especially bright at optical wavelengths! They were instead discovered in the infrared. It seems they are powered by bursts of massive star formation: clusters of massive stars, each star thousands or even tens of thousands of times more luminous than our Sun, and all of them buried in dusty natal clouds of material that block their visible light. Massive stars, however, are also very short-lived, lasting perhaps only tens of millions of years before exploding in as supernovae (compared with our Sun's current age of 5 billion years). Hence these luminous galaxies are called starburst galaxies, and they are indeed lit up in short bursts of star forming activity. Messier 82 in the constellation of Ursa Major is a nearby example of a luminous starburst galaxy, and the multi-wavelength image at the left reveals the dramatic disruptive power of the strong winds produced by all of those massive young stars.
Why? What causes a galaxy to go wild and suddenly produce massive new stars? Is this a normal phase that every galaxy must undergo? Did the Milky Way itself have a starburst...or will it perhaps erupt in the future? Massive stars produce and disperse most of the chemical elements essential to life ... did the carbon, oxygen, and iron on Earth come originally from a starburst? Because starburst galaxies are so bright (at least in the infrared) they can be seen to almost the edges of the known Universe -- what can these fantastically remote objects tell us about stars, galaxies, and the physics at cosmological distances, when the universe was in its infancy?
These are some of the questions which CfA scientists are trying to answer in their studies of Starburst Galaxies.
Matthew Ashby, Howard Smith, Zhong Wang, Steve Willner, Andreas Zezas