Astronomers measure exact distance to Milky Way’s most distant stars from Earth
An international team of astronomers have for the first time measured the exact distance to the Milky Way’s most distant stars from Earth and found that these stars are about a million light-years away from us, helping scientists clarify the position of the boundaries of the Galaxy, TASS reports
“This study has drastically changed our understanding of where the outer boundaries of our Galaxy lie. It turned out that both the Milky Way and its nearest neighbour, the Andromeda Galaxy, are so large that there is virtually no empty space between them,” said Prof. Raja GuhaThakurta, whose words were quoted by the press service of the University of California at Santa Cruz.
Our Galaxy is a spiral disk-like structure, which is surrounded by the so-called galactic halo. It is a diffuse cloud of gas, dust and luminaries ejected from the disk of the Milky Way or originated outside of it. Astronomers have long been interested in how large the halo is and how many stars are present in it, which is important for determining the size and boundaries of the Galaxy, as well as the mass of visible and dark matter present in it.
This task is one of the most difficult problems in astronomy, since the exact distance to distant stars is extremely difficult to determine without knowing their exact size and absolute luminosity. Scientists overcome the problem by observing certain classes of variable stars, whose luminosity changes smoothly over time as a result of complex physical processes in the depths of these stars.