A new method for estimating the masses of galaxies promises more reliable results, especially when applied to extensive data sets that give modern sky surveys. In this study, conducted by a group of astronomers led by Ekta Patel of the University of Arizona, USA, the first observed movements of the Milky Way galaxies in three dimensions in combination with powerful computer models give a more accurate estimate of the mass of the Milky Way, compared with previous studies.
Since we are inside our Galaxy, the estimation of its mass can not be carried out by its own movements, and instead scientists use to estimate the mass of the Milky Way the motion of small cosmic objects surrounding our Galaxy-galaxies-satellites and stellar streams. The motion of such objects depends heavily on the mass of the Milky Way, so by studying its parameters, scientists can estimate the mass of the Galaxy. According to estimates obtained from previous studies, the mass of the Milky Way ranges from 700 billion to 2 trillion solar masses.
Patel and her team improve this method of estimating the mass of the Galaxy, changing from position measurements in the sky and the motion of small objects of the Milky Way to their angular moments, which do not depend on the distance to the object. The application of this method allowed researchers to refine the mass of our Galaxy, which, according to new estimates, is 960 billion solar masses. These results also agree with the notion that the mass of the Milky Way is slightly smaller than the mass of the neighboring Andromeda galaxy.
The study was presented at the annual annual meeting of the American Astronomical Society, held recently in Denver, Colorado.