Growing Stars Are Tidying the Universe

NASA/JPL-Caltech/L. Cieza (University of Texas at Austin) via Wikimedia Commons // Public Domain
NASA/JPL-Caltech/L. Cieza (University of Texas at Austin) via Wikimedia Commons // Public Domain / NASA/JPL-Caltech/L. Cieza (University of Texas at Austin) via Wikimedia Commons // Public Domain

The world is kind of a mess these days, but at least our universe is cleaning itself up.* Astronomers say rapidly forming stars are gobbling up more cosmic debris than ever before, effectively cleaning up outer space. They presented their findings at the 2016 National Astronomy Meeting in Nottingham, UK.

This discovery was made possible by the European Space Agency’s Herschel Astrophysical Terahertz Large Area Survey (Herschel ATLAS) project. For four years, the Herschel Space Observatory drifted through the black, bearing the largest and most powerful infrared telescope ever flown in space. Through Herschel ATLAS, astronomers gained access to the observatory’s astonishingly detailed images and insights. 

We are so far away from other objects in space that looking into the universe is also literally looking back in time. To find out if and how the process of star formation has changed, a team of researchers used Herschel data to look 12 billion years into the past.

Cosmic dust is exactly what it sounds like: solid particles hanging in the space between the stars. This dust is the raw material of galaxies. A burgeoning star sucks in nearby debris, growing and absorbing, even as it empties the space around it. While star-gobbled cosmic dust shines, free-floating dust absorbs light, which renders it nearly impossible to see from Earth. Fortunately, Herschel’s telescope could see it.

Project co-leader Steve Eales researches physics and astronomy at Cardiff University. “We were surprised to find that we didn't need to look far in the past to see signs of galaxy evolution,” he said in a press statement. “Our results show that the reason for this evolution is that galaxies used to contain more dust and gas in the past, and the universe is gradually becoming cleaner as the dust is used up." 

Loretta Dunne is another of the project co-leaders from Cardiff University. "Before Herschel, we only knew of a few hundred such dusty sources in the distant universe, and we could only effectively 'see' them in black and white,” she said.

“Herschel, with its five filters, has given us the equivalent of technicolour, and the colour of the galaxy tell us about their distances and temperatures," Dunne said. "So we now have half a million galaxies we can use to map out the hidden star formation in the universe."

*We realize this may be small consolation.

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