Astronomers from the University of Victoria and Yale University have made a groundbreaking discovery of an ancient star system called Ursa Major III / UNIONS 1 (UMa3/U1) that is orbiting our galaxy. This star system is the faintest and lowest-mass Milky Way satellite ever found, and it may be one of the most dark matter-dominated systems known.
Located in the Ursa Major (Great Bear) constellation, UMa3/U1 is relatively close to us, about 30,000 light-years from the sun. It had remained undetected due to its extremely low luminosity,” says Simon Smith, an astronomy graduate student at the University of Victoria and lead author of the study.
Observations have revealed that UMa3/U1 is a small stellar system with around 60 stars that are over 10 billion years old, spanning just 10 light-years across. It has an extremely low mass, making it 15 times less massive than the faintest suspected dwarf galaxy.
UMa3/U1 was initially discovered using data from the Ultraviolet Near Infrared Optical Northern Survey (UNIONS) at CFHT and Pan-STARRS. Further study using Keck Observatory’s Deep Imaging Multi-Object Spectrograph (DEIMOS) confirmed that UMa3/U1 is a gravitationally-bound system, either a dwarf galaxy or a star cluster.
2024-03-28 15:00:04
Post from phys.org