The massive star cluster NGC 346, located in the Small Magellanic Cloud, has long puzzled astronomers with its unusual shape. Now, researchers using two separate methods have determined that this shape is partly due to stars and gas spiraling through the center of this cluster in a river-like motion. The red spiral superimposed on NGC 346 traces the movement of stars and gas toward the center. Scientists say this spiral motion is the most efficient way to fuel star formation from the outside to the center of the cluster. Credit: NASA, ESA, Andi James (STScI)
Stars are the machines that sculpt the universe, but researchers still don’t know exactly how they form. Scientists turned to the Small Magellanic Cloud, a satellite galaxy of the
” data-gt-translate-attributes=”[{” attribute=””>Milky Way, to understand the frenzied “baby boom” of star birth that occurred early in the universe’s history. This nearby galaxy has a simpler chemical composition than the Milky Way, which makes it similar to the galaxies found in the younger universe, when heavier elements were less abundant. As a result, it can serve as a proxy for the early universe.
Two separate research studies – the first with the
The massive star cluster NGC 346, located in the Small Magellanic Cloud, has long intrigued astronomers with its unusual shape. Now researchers using two separate methods have determined that this shape is partly due to stars and gas spiraling into the center of this cluster in a river-like motion. Credit: NASA, ESA, Andi James (STScI)
NASA’s Hubble Finds Spiraling Stars, Providing Window into Early Universe
Spirals are prevalent in nature — from the whirlpool of a hurricane, to pinwheel-shaped protoplanetary disks around newborn stars, to the vast realms of spiral galaxies across our universe.
Now astronomers are bemused to discover young stars that are spiraling into the center of a massive cluster of stars in the Small Magellanic Cloud, a satellite galaxy of the Milky Way.
The outer arm of the spiral in this massive, oddly shaped stellar nursery called NGC 346 may be feeding star formation in a river-like motion of gas and stars. Scientists say that this is an efficient way to fuel star birth.
The Small Magellanic Cloud has a simpler chemical composition than the Milky Way. This makes it similar to the galaxies found in the younger universe when heavier elements were more scarce. Because of this, the stars in the Small Magellanic Cloud burn hotter and therefore run out of their fuel faster than in our Milky Way.
Even though it can serve as a proxy for the early universe, the Small Magellanic Cloud is also one of our closest galactic neighbors, at just 200,000 light-years away.
Discovering how stars form in the Small Magellanic Cloud offers a new twist on how a firestorm of star birth may have occurred early in the universe’s history, when it was undergoing a “baby boom” about 2 to 3 billion years after the big bang (the universe is now 13.8 billion years old).
According to the new findings, the process of star formation there is similar to that in our own Milky Way.
NGC 346 boasts the mass of 50,000 Suns, despite being only 150 light-years in diameter. Its intriguing shape and rapid star-formation rate have baffled astronomers. It required the combined power of
However, this cluster is relatively far away, inside a neighboring galaxy. This means the amount of observed motion from our vantage point is very small and therefore difficult to measure. These extraordinarily precise observations were possible only because of Hubble’s outstanding resolution and high sensitivity. Additionally, Hubble’s three-decade-long history of observations provides a baseline for astronomers to follow minute celestial motions over time.
The second team, led by Peter Zeidler of AURA/STScI for the European Space Agency (ESA), used the ground-based VLT’s Multi Unit Spectroscopic Explorer (
Half of the Hubble data for this study of NGC 346 is archival, with the first observations taken 11 years ago. These observations were recently repeated to trace the motion of the stars over time. Given the telescope’s longevity, more than 32 years of astronomical data are now contained in the Hubble data archive, which can power unprecedented, long-term studies.
“The Hubble archive is really a gold mine,” said Sabbi. “There are so many interesting star-forming regions that Hubble has observed over the years. Given that Hubble is performing so well, we can actually repeat these observations. This can really advance our understanding of star formation.”
The teams’ findings appear today (September 8) in The Astrophysical Journal.
Reference: “The Internal Line-of-Sight Kinematics of NGC 346: The Rotation of the Core Region” by Peter Zeidler, Elena Sabbi and Antonella Nota, 8 September 2022, The Astrophysical Journal.
DOI: 10.3847/1538-4357/ac8004
Observations with NASA’s
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