April 26, 2019

02.05.10- Star-birth in the Early Universe.

Astronomers are shedding new light across the spectrum on an old cosmological mystery. It’s well documented that the rate of star formation today is much less than what it was early on in the history of the universe; what isn’t completely understood is why. Was there simply an abundance of star forming material available, or was the process of star formation more efficient? Either trend may have a huge significance as to how the current and future evolution of the universe plays out; stars such as our Sun are metal rich and formed as a result of the recycling of cosmic material from that first primeval generation of stars. Even non-fusion sustaining bodies such as the Earth, Sandra Bullock, and your IPad owe their elemental composition largely to those original stars.  Now, a team led by Michael Cooper of the University of Arizona’s Steward Observatory is tackling the dilemma from a fresh angle. The galaxies in question are about 4 billion years old; the universe is an estimated 13.7 billion years of age. In that tender young era, the rate of observed star formation was about 10 times what we see today. Traditional surveys have looked at larger, brighter, and more easily observable galaxies in the energetic throes of star formation. But is that the best approach? This method largely ignores the vast population of fainter, harder to spot galaxies. “It is a little like studying only individuals who are seven feet tall instead of those who fall in a more common range of height,” stated Cooper. Their unique approach has been to examine a selection of average galaxies culled from 50,000 objects to study across a range of wavelengths. Instruments called into action included the Hubble and Spitzer Space telescopes as well as an array of ground-based radio telescopes. Analysis across the spectrum shows that a much greater concentration of gas and dust was available to fuel star formation than what we see today; these galaxies also really light up in the radio and infrared, as pictured above… could we be looking at snapshots resembling our galaxies’ grandparents?