Galaxy, star, and planet formation

默里教授致力于星系、恒星和行星形成的定量研究。星系形成恒星的速度随着宇宙年龄的变化而变化。目前，螺旋星系每年形成一到十个太阳。令人惊讶的是，包含10亿到100亿太阳质量气体的螺旋星系形成恒星的速度如此之慢。默里教授正在探索这样一种观点，即年轻恒星的光线限制了恒星形成的速度。相比之下，50亿年前，当宇宙大约是现在年龄的一半时，大多数星系形成于每年10到100个太阳之间。当第一次被发现时，恒星形成速度的增加似乎令人惊讶，但近年来人们发现，星系中含有的气体大约是当时的十倍。最后，在这些较年轻的星系中，每个轨道周期内转化为恒星的气体比例与现在的星系中的比例是相同的。默里再次试图确定，与较高的恒星形成率相关的较高光度是否解释了气体形成恒星的速度较慢的原因。

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.