Why Starburst Galaxies Birth More Baby Stars in Less Time Than Ellipticals (VIDEO)

Why do starburst galaxies "burst?" While some galaxies transmute gas into new stars at a dizzying pace, other galaxies never experience this unprecedented growth. Now, scientists may have found out why by dissecting a cluster of star-forming clouds at the heart of NGC 253, a starburst galaxy close to the Milky Way.

"All stars form in dense clouds of dust and gas," said Adam Leroy, one of the researchers, in a news release. "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, is a disk-shaped galaxy that's currently undergoing intense starburst. Located just 11.5 million light-years from Earth, the galaxy is perfect for detailed study. In order to understand this burst of star formation, the researchers pulled apart the region layer by layer.

The scientists used ALMA to first identify ten distinct stellar nurseries inside the heart of Sculptor. Then, the researchers mapped the distribution of about 40 millimeter-wavelength "signatures" from different molecules inside the center of the galaxy. This was particularly important since different molecules correspond to different conditions in and around star-forming clouds. For example, carbon monoxide corresponds to massive envelopes of less dense gas that surround stellar nurseries.

The researchers then compared the concentration, distribution and motion of these molecules to peel apart the star-forming clouds in Sculptor. In the end, they found these clouds are more massive, ten times denser and more turbulent than similar clouds in normal spiral galaxies.

The findings reveal that it matters what kind of stellar nurseries are present for star formation.

"These differences have wide-ranging implications for how galaxies grow and evolve," said Leroy. "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."

The findings are published in the Astrophysical Journal.

Want to learn more? Check out the video below, courtesy of Vimeo.

For more great science stories and general news, please visit our sister site, Headlines and Global News (HNGN).

NGC253 -- Why Starburst Galaxies "Burst" from NRAO Outreach on Vimeo.