Starburst

Chile’s ALMA telescope makes galactic discovery

Astronomers in the Atacama observe a galaxy in such turmoil that it is close to blowing itself apart, providing a possible reason for the universe’s scarcity of massive galaxies.

Thursday, August 01, 2013 Category: Education
A three-dimensional view of the gas outflows from the Sculptor Galaxy. Photo by ESO. A three-dimensional view of the gas outflows from the Sculptor Galaxy. Photo by ESO.

 

The world’s biggest ground based observatory in Chile may have solved another long-standing cosmological mystery, after discovering a galaxy that is ejecting gas at such a rate it is heading for collapse.

At around 11.5 million light years from the Milky Way Galaxy, the Sculptor Galaxy is one of our closest neighbors. Aside from its proximity, Sculptor is of particular interest to astronomers as it is a “starburst” galaxy — one of intense star formation.

Sculptor has been the subject of study before, but only when the Atacama Large Millimeter/submillimeter Array’s (ALMA) radio telescopes were turned toward it was the galaxy’s most exciting feature uncovered. Huge streams of gas billow away from Sculptor at such a rate that the total amount of gas ejected would add up to more gas than actually went into forming the galaxy’s stars in the same time. If the the galaxy continues to do this, it will run out of gas in about 60 million years.

For decades, scientists have not been able to explain the scarcity of massive galaxies in the universe, and this new discovery goes a long way to explaining this mystery. Alberto Bolatto of the University of Maryland and head of the study, explains that ALMA’s cutting edge technology was the key to uncovering these new observations.

“With ALMA’s superb resolution and sensitivity, we can clearly see for the first time massive concentrations of cold gas being jettisoned by expanding shells of intense pressure created by young stars,” Bolatto said. “The amount of gas we measure gives us very good evidence that some growing galaxies spew out more gas than they take in. We may be seeing a present-day example of a very common occurrence in the early universe.”

Prior to ALMA’s discovery, computer models had predicted that older galaxies should be far more massive and contain many more stars than astronomers have actually viewed in the cosmos. Scientists have theorised beforehand that galactic winds must blow gas and material out of galaxies in periods of intense star formation, though have not observed evidence of this until now.

“For me, this is a prime example of how new instruments shape the future of astronomy,” Fabian Walter, lead investigator at the Max Planck Institute of Astronomy, said. “We have been studying the starburst region of NGC 253 (Sculptor) and other nearby starburst galaxies for almost ten years. But before ALMA, we had no chance to see such details. The study used an early configuration of ALMA with only 16 antennas. It’s exciting to think what the complete ALMA with 66 antennas will show for this kind of outflow.”

Due to its almost non-existent humidity and clear skies, the Atacama is the world’s premier location for astronomy. Chile is home to almost half the world’s telescope infrastructure, and this is set to increase to over two thirds in the next decade.

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