Stars are the machines that shape the universe, but scientists don’t quite know how they form. To understand the frenzied “baby boom” of star birth that occurred early in the history of the universe, researchers turned to the Small Magellanic Cloud, a satellite galaxy of the Milky Way. This nearby galaxy has a simpler chemical makeup than the Milky Way, making it similar to the galaxies in the younger Universe, when heavier elements were scarcer. This allows it to serve as a proxy for the early universe.
Two separate studies – the first with the Hubble Space Telescope and the second with the European Southern Observatory’s Very Large Telescope – recently came to the same conclusion. Using different methods, the independent teams found young stars spiraling toward the center of a massive star cluster NGC 346 in the Small Magellanic Cloud. This river-like movement of gas and stars is an efficient way to fuel star birth, researchers say. The results of the teams show that the process of star formation in the Small Magellanic Cloud is similar to that in our own Milky Way.
Nature loves spirals — from the vortex of a hurricane, to pinwheel-shaped protoplanetary disks around newborn stars, to the vast realms of spiral galaxies in our universe.
Now astronomers are baffled to find young stars spiraling toward the center of a huge cluster in the Small Magellanic Cloud, a satellite galaxy of the Milky Way.
The outermost arm of the spiral in this huge, oddly shaped stellar nursery, called NGC 346, may be fueling star formation in a river-like movement of gas and stars. This is an efficient way to fuel star birth, researchers say.
The Small Magellanic Cloud has a simpler chemical makeup than the Milky Way, making it similar to the galaxies in the younger Universe, when heavier elements were scarcer. As a result, the stars in the Small Magellanic Cloud burn hotter and run out of fuel faster than in our Milky Way.
While the Small Magellanic Cloud is a proxy for the early Universe, it is also one of our closest galactic neighbors at 200,000 light-years away.
Learning how stars form in the Small Magellanic Cloud offers a new look at how a star-birth firestorm may have occurred early in the universe’s history, when it underwent a “baby boom” about 2 to 3 billion years after the Big Bang ( the universe is now 13.8 billion years old).
The new results show that the process of star formation there is similar to that in our own Milky Way.
NGC 346 is only 150 light-years across and has a mass of 50,000 suns. Its intriguing shape and rapid star-forming rate have puzzled astronomers. The combined power of NASA’s Hubble Space Telescope and the European Southern Observatory’s Very Large Telescope (VLT) was needed to unravel the behavior of this mysterious-looking stellar breeding ground.
“Stars are the machines that shape the universe. We wouldn’t have life without stars, and yet we don’t fully understand how they form,” explains study leader Elena Sabbi of the Space Telescope Science Institute in Baltimore. “We have several models that make predictions, and some of these predictions are contradictory. We want to determine what regulates the process of star formation because these are the laws we also need to understand what we see in the early universe.”
Researchers determined the motion of the stars in NGC 346 in two different ways. Using Hubble, Sabi and her team measured the changes in the positions of the stars over 11 years. The stars in this area move at an average speed of 2,000 miles per hour, meaning they move 200 million miles in 11 years. This is about 2 times the distance between the sun and the earth.
But this cluster is relatively distant, in a neighboring galaxy. This means that the amount of observed movement is very small and therefore difficult to measure. These extraordinarily accurate observations were only possible thanks to Hubble’s superb resolution and high sensitivity. Also, Hubble’s three-decade long history of observations provides a baseline for astronomers to track minute celestial movements over time.
The second team, led by Peter Zeidler of AURA/STScI for the European Space Agency, used the ground-based VLT’s Multi Unit Spectroscopic Explorer (MUSE) instrument to measure radial velocity, which determines whether an object is an observer. approaching or departing.
“What was really great is that we used two completely different methods with different facilities and basically came to the same conclusion, independently of each other,” said Zeidler. “With Hubble you can see the stars, but with MUSE we can also see the gas movement in the third dimension, and it confirms the theory that everything turns inward.”
But why a spiral?
“A spiral is really the good, natural way to feed star formation from the outside to the center of the cluster,” explains Zeidler. “It’s the most efficient way for stars and gas that fuels more star formation to move toward the center.”
Half of the Hubble data for this study of NGC 346 has been archived. The first observations were made 11 years ago. They were recently repeated to track the movement of the stars over time. Given the telescope’s longevity, the Hubble data archive now contains more than 32 years of astronomical data enabling unprecedented, long-term studies.
“The Hubble archive really is a gold mine,” says Sabbi. “There are so many interesting star-forming regions that Hubble has observed over the years. Since Hubble is doing so well, we can replicate these observations. This could greatly expand our understanding of star formation.”