Research Matters

Research Matters

How Stars Form


Greg Rudnick is observing one the earliest known clusters of galaxies, which is 10 billion light years away. Because of a “trick” of nature, he is getting a snapshot of the Universe when it was 10 billion years younger than it is today.

Episode #112



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Transcript


A researcher peers into the universe’s ancient past to better know how stars form. From the University of Kansas, this is Research Matters. I’m Brendan Lynch.

Light that leaves stars in distant galaxies takes billions of years to reach our planet. Greg Rudnick, assistant professor of physics at KU, is observing one the earliest known clusters of galaxies, which is 10 billion light years away.  Because of this “trick” of nature, he is getting a snapshot of the Universe when it was 10 billion years younger than it is today.

Rudnick: If we look at galaxies that are 9 or 10 billion light years away, we’re seeing them when the universe was only 20 or 30 percent of its current age. We’re literally looking back in time. So we can look at galaxies back then and measure how many stars were in each of them &mdash and see that galaxies back then were forming stars at a much higher rate.”

Rudnick uses the Expanded Very Large Array &mdash a vast radio astronomy observatory in New Mexico consisting of 27 huge antennas. It will allow him to gauge the abundance of molecular gasses present in a cluster of seven galaxies.  

Rudnick: Stars form from clouds of molecular gas.  So measuring how much molecular gas there is tells us what the fuel supply for star formation was in young galaxies. We want to measure how long that fuel supply will last given the rate in which it’s forming new stars. Is the gas enough to supply it for a long time, or is about to shut off? By looking at the motion of these gas molecules, we can figure how fast the gas in the galaxy is moving around, and that in turn will tell us how much total mass there is in the galaxy.

The observation of the distant galaxy cluster will break new ground in understanding in the fueling of star formation.

Rudnick: The prediction of galaxy formation models is that the gas supply of galaxies is cut off when they fall into these clusters.  These observations will give us the first test of this in the distant Universe.

For more about how stars form, log on to Research Matters dot KU dot EDU. For the University of Kansas, I’m Brendan Lynch.

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Researcher peers into universe's ancient past to better know how stars form


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