Galaxy, star, and planet formation

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Professor Murray pursues quantitative studies of galaxy, star, and planet formation. Galaxies form stars at rates that vary as the universe ages. Currently, spiral galaxies form between one and ten Suns per year. It is surprising is that spiral galaxies, which contain somewhere between a billion and ten billion solar masses of gas, form stars so slowly. Professor Murray is exploring the idea that the light from young stars is what limits the rate of star formation. In contrast, five billion years ago, when the universe was roughly half its present age, most galaxies formed between ten and one hundred Suns per year. When first discovered, this increased rate of star formation seemed surprising, but in recent years it has been found that galaxies contained roughly ten times as much gas at that time. In the end, the fraction of gas turned into stars per orbital period is the same in these younger galaxies as it is in present day galaxies. Again, Murray is trying to determine if the higher luminosity associated with the higher star formation rate explains the rather slow rate at which gas is made into stars.