Astronomers using the Multi Unit Spectroscopic Explorer (MUSE) instrument on ESO’s Very Large Telescope (VLT) and the NASA/ESA Hubble Space Telescope have spotted young stars that are spiraling into the center of NGC 346, a massive star cluster in the Small Magellanic Cloud.
NGC 346 is an open star cluster located about 210,000 light-years away in the constellation of Tucana.
It resides in the Small Magellanic Cloud, a dwarf galaxy that is a satellite of our Milky Way Galaxy.
Also known as ESO 51-10, Kron 39 or Lindsay 60, it was discovered on August 1, 1826 by the Scottish astronomer James Dunlop.
NGC 346 has a diameter of 150 light-years and a mass of 50,000 solar masses.
Its intriguing shape and rapid star formation rate have puzzled astronomers for years.
“Stars are the machines that sculpt the Universe. We would not have life without stars, and yet we don’t fully understand how they form,” said Dr. Elena Sabbi, an astronomer at the Space Telescope Science Institute.
“We have several models that make predictions, and some of these predictions are contradictory.”
“We want to determine what is regulating the process of star formation, because these are the laws that we need to also understand what we see in the early Universe.”
In their new study, Dr. Sabbi and her colleagues aimed to study the motion of NGC 346’s stars.
Using the data from Hubble, they measured the changes of the stars’ positions over 11 years.
The stars in this region are moving at an average velocity of 3,219 km/h (2,000 mph), which means that in 11 years they move 322 million km (200 million miles).
But NGC 346 is relatively far away. This means the amount of observed motion is very small and therefore difficult to measure.
These extraordinarily precise observations were possible only because of Hubble’s exquisite resolution and high sensitivity.
Using the VLT/MUSE data, the astronomers measured the radial velocities of stars in the central region of NGC 346.
“What was really amazing is that we used two completely different methods with different facilities and basically came to the same conclusion, independent of each other,” said Dr. Peter Zeidler, an astronomer with the AURA for the European Space Agency and the Space Telescope Science Institute.
“With Hubble, you can see the stars, but with MUSE we can also see the gas motion in the third dimension, and it confirms the theory that everything is spiraling inwards.”
“A spiral is really the good, natural way to feed star formation from the outside toward the center of the cluster,” he added.
“It’s the most efficient way that stars and gas fueling more star formation can move towards the center.”
The results were published in the Astrophysical Journal.
Peter Zeidler et al. 2022. The Internal Line-of-Sight Kinematics of NGC 346: The Rotation of the Core Region. ApJ 936, 136; doi: 10.3847/1538-4357/ac8004
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