The weakest satellite of the Milky Way may not be what astronomers thought. “These results solve an important secret in astrophysics”
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Ursa Major III, a weak star cluster over 30,000 light years away, can be bound to hidden black holes instead of dark matter. | Credit: CFHT/Union/S.Gwyn
A ghostly object that circles the Milky Way has astronomer questioning its composition: Is it a dark matter dominated dwarf galaxy or a star cluster that is bound to a hidden swarm of black holes?
Ursa Major III/unions 1 (UMA3/U1), the weakest known satellite of our galaxy, circles the Milky Way at a distance of more than 30,000 light years. It is a compact star system that contains only 60 visible stars.
Ursa Major III was long considered dark Dwarf galaxy -a small galaxy with an unusually high mass-to-light ratio that indicates this dark matter – But new evidence suggests that instead it is a compact star cluster, the gravity of which is held together by a core of black holes and neutron stars a statement from the University of Bonn in Germany.
“Form dark star clusters Star cluster“Hosein Haghi, co-author of the study, which is examined at the University of Bonn, said in the explanation.
After repeated gravitational encounters with the Milky Way, only one dense, invisible core of Ursa Major III Remains. Since this dark core does not borrow light, the astronomers initially thought that the cluster was packed with dark matter.
With the help of computer simulations and observation data of the orbital movement and chemical composition of URSA Major III, astronomers calculated the gravitational changes of thousands of stars with great accuracy in order to reconstruct the structure of the object over time. The simulations show that a thick core of Black holes Could hold the remaining stars gravitarian without dark matter being necessary, according to the statement.
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“For the first time, our work shows that these objects are most likely normal star clusters,” said Pavel Kroupa, co -author of the study, in the explanation. “These results solve a big secret in astrophysics.”
Regardless of whether a dwarf galaxy or a star cluster, Ursa Major III provides important information on the formation and composition of the Milky Way.
Your results were Published on August 7th In the Astrophysical Journal Letters.