Astronomers believe that the outer arm of this spiral stars and the gas could provide a river-like flow of gas fueling star formation in the stellar nursery, called NGC 346, seen in the new image taken by the Hubble Space Telescope. The discovery could provide important clues about how stars were born when the 13.8 billion year old galaxy it was only a few billion years old and was going through a stellar baby boom of intense star formation. “Stars are the engines that sculpt the universe. We wouldn’t have life without stars, and yet we don’t fully understand how they form,” study leader Elena Shabi and an astronomer at the Space Telescope Science Institute in Baltimore, which manages Hubble, told the a statement.
Young stars swirl in the heart of the Small Magellanic Cloud. (Image credit: NASA, ESA, A. James (STScI)) “We have several models making predictions and some of those predictions are contradictory,” he added. “We want to determine what regulates the star formation process because these are the laws we need to also understand what we see in the early universe.” NGC 346 is just 150 light–years in diameter and contains stellar material with a mass equivalent to 50,000 suns. The region has puzzled astronomers with its intense rate of star formation. The Small Magellanic Cloud that hosts NGC 346 is just 200,000 light-years from Earth, meaning astronomers are seeing younger light than from more distant galaxies that can reveal the early universe. However, the dwarf galaxy is analogous to early galaxies in other ways. The Small Magellanic Cloud has a simpler chemical composition than the Galaxy, just as early galaxies that had not yet been enriched with heavier elements by successive generations of stars that went supernova explode and litter space with elements forged during their lifetimes. Because of this chemical simplicity, stars in the Small Magellanic Cloud are hotter and burn through fuel faster than stars in our Milky Way, meaning they age faster than stars in our galaxy. However, despite these differences, the researchers found that star formation in the Small Magellanic Cloud proceeds similarly to our Milky Way.
The red spiral above the stellar nursery NGC 346 shows the movement of gas and stars in its heart as it fuels star formation. (Image credit: NASA, ESA, A. James (STScI))
Watching a spiral of stars
To study star formation in the Small Magellanic Cloud, astronomers turned to the Hubble Space Telescope and Very large telescope (VLT) in northern Chile to examine the motion of stars in two different ways. Sabbi and her team used Hubble to measure changes in the positions of stars in the galaxy over 11 years. The stars move at about 2,000 mph (3,200 km/h), which means that in 11 years they travel about 200 billion miles (320 billion kilometers), or a little more than twice the distance between Earth and the Sun. But that’s still a short distance when viewed from our perch 150 light-years away, meaning it took the power of Hubble to detect and resolve these tiny shifts in the stars’ position. Meanwhile, a second crew of astronomers led by European Space Agency (ESA) researcher Peter Zeidler used the VLT’s Multi Unit Spectroscopic Explorer (MUSE) instrument to measure the stars’ radial velocity, how fast a star is moving towards or away by the observer. . Both observational methods revealed a spiral of stars feeding into the heart of NGC 346, carrying star-forming gas with them. “What was really surprising is that we used two completely different methods with different facilities and basically came to the same conclusion independently,” Zeidler said in the same statement. “With Hubble, you can see the stars, but with MUSE we can also see the movement of gas in the third dimension, and it confirms the theory that everything spirals inward.” Seidler also explained the importance of spiral formation in the birth of stars. “A spiral is a very good, natural way to fuel star formation from the outside to the center of the cluster,” he explained. “It’s the most efficient way that the stars and gas that fuel more star formation can move toward the center.” The team’s research was published on Thursday (September 8) in the The Astrophysical Journal. Follow us on Twitter @Spacedotcom and up Facebook.
