A neighboring galaxy has astronomers seeing stars.
A spiral galaxy like the Milky Way can't quite keep up with a starburst galaxy like NGC 253, which was analyzed by Atacama Large Millimeter/Submillimeter Array (ALMA) in Chile.
"All stars form in dense clouds of dust and gas," said Ohio State University's Adam Leroy, an astronomer formerly with the National Radio Astronomy Observatory (NRAO), according to a press release from NRAO. "Until now, however, scientists struggled to see exactly what was going on inside starburst galaxies that distinguished them from other star-forming regions."
NGC 253, also known as the Sculptor Galaxy, was mapped out by Leroy and his teammates. Sculptor Galaxy is a disk-shaped galaxy that is going through a bit of phase - an intense starburst phase. At 11.5 million light-years from Earth, Sculptor is pretty close to the Milky Way, which makes it a prime subject of study.
"There is a class of galaxies and parts of galaxies, we call them starbursts, where we know that gas is just plain better at forming stars," said Leroy, according to the press release. "To understand why, we took one of the nearest such regions and pulled it apart - layer by layer - to see what makes the gas in these places so much more efficient at star formation."
ALMA was able to identify 10 distinct stellar nurseries inside Sculptor, something that other telescopes lacking the high resolution and sensitivity of ALMA couldn't have done without blurring the nurseries together.
There are about 40 millimeter-wavelength signatures from different molecules inside the center of the galaxy, like carbon monoxide (large gatherings of less dense gas), hydrogen cyanide (found in dense areas of active star birth) and rare molecules like H13CN and H13CO+ (indicating even denser regions). The astronomers identified and mapped each area of molecules in order to take a peek inside the star-forming clouds in Sculptor. They found that the clouds in a starburst galaxy are 10 times denser, more massive and more chaotic that normal spiral galaxies.
"These differences have wide-ranging implications for how galaxies grow and evolve," said Leroy, according to the press release. "What we would ultimately like to know is whether a starburst like Sculptor produces not just more stars, but different types of stars than a galaxy like the Milky Way. ALMA is bringing us much closer to that goal."
These results have been accepted for publication in the Astrophysical Journal and were presented on Sunday at a news conference at the American Association for the Advancement of Science (AAAS) meeting in San Jose, Calif.
From the press release:
The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.
The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).
ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.
