Scientists have discovered 60 ultra-faint stars, the lightest satellite galaxy ever found – which could lead to a new galaxy we’ve never seen before.
Astronomers found the star system in the constellation Ursa Major, which sits around 30,000 light-years away from the sun. The Milky Way holds at least 50 satellite galaxies, with the smallest tending to be home to thousands or billions of stars.
But this new discovery only has 60.
It has 16 times the mass of our sun, which is minuscule compared to the Milky Way itself which is 1.5 trillion times.
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In a new study the strange discovery could be the start of understanding a new class of galaxies that have been travelling in space under the radar until now.
Simon Smith, graduate student at the University of Victoria in Canada, said: “This discovery may challenge our understanding of galaxy formation and perhaps even the definition of a ‘galaxy’.
“UMa3/U1 had escaped detection until now due to its extremely low luminosity.
The stars, stretching over 10 light years, were first seen using three telescopes based in Hawaii. Astronomers used data collected by the Ultraviolet Near Infrared Optical Northern Survey, and the WM Keck Observatory, to confirm the star system are bound gravitationally.
The study was published in The Astrophysical Journal in January.
But scientists can’t understand yet how the galaxy has remained unharmed for at least 10 billion years, as other observations in space reveal the Milky Way’s gravitational pull can tear apart dwarf galaxies if they get too close.
“The object is so puny that its long-term survival is very surprising,” Will Cerny, a graduate student in the Yale University Department of Astronomy and a co-author of the study, said.
“Either UMa3/U1 is a tiny galaxy stabilized by large amounts of dark matter, or it’s a star cluster we’ve observed at a very special time before its imminent demise.”
Another theory is that dark matter is to blame for holding the galaxy together, and if so, could lead to new discoveries about the behavior of dark matter.
“Whether future observations confirm or reject that this system contains a large amount of dark matter, we’re very excited by the possibility that this object could be the tip of the iceberg – that it could be the first example of a new class of extremely faint stellar systems that have eluded detection until now,” Cerny said.
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