Astronomers recently made a groundbreaking discovery by identifying the dimmest satellite of the Milky Way known to date. Referred to as Ursa Major III/Unions 1 (UMA3/U1), this object not only emits the least amount of light, but also possesses the smallest mass compared to other well-known satellites of our galaxy. Additionally, UMA3/U1 is considered to be one of the most dark matter-rich systems.
With a mass equivalent to only 16 times that of the Sun, UMA3/U1 is comprised of around 60 luminous stars scattered across a 20-light-year space. The satellite is believed to have formed in the early stages of the Universe given that its stars are over 10 billion years old.
Situated in the constellation Big Dipper, UMA3/U1 lies approximately 30,000 light years away from the Sun. Its extremely low luminosity had previously kept it hidden from observation, making it either the faintest among known ancient star clusters or the dimmest and closest dwarf galaxy ever detected.
The discovery of this diminutive system was made possible due to the high-quality data collected during the research. Initially, data from the Ultraviolet Near Infrared Optical North Survey (Unions) conducted with the CFHT and Pan-STARRS telescope led to the detection of UMA3/U1. Subsequently, the Deimos spectrograph at the KEK Observatory was utilized for a more thorough investigation of the star system.
Further analysis revealed that all stars within UMA3/U1 exhibit similar velocities in space and share a comparable chemical composition, ruling out the possibility of a chance grouping of stars. This finding paves the way for future observations to affirm the prevalence of dark matter within the satellite.
This groundbreaking discovery serves as a crucial validation of the theory regarding the Universe’s origins, which suggests that gravitational forces draw numerous satellite star systems together to form galaxies like the Milky Way. The significant amount of dark matter present likely aided UMA3/U1 in surviving the intense tidal forces exerted by the Milky Way.
Astronomers are eager to delve deeper into their study of UMA3/U1 to gain a more precise understanding of its dark matter composition, which could lead to greater insights into the universe’s structure.