How heavy is the Milky Way?

How much mass does the Milky Way have? To answer this question, a team from the University of Arizona in Tucson combined data about the orbits of several small satellite galaxies of the Milky Way with extensive computer simulations. For these, 20,000 large galaxies and their satellites were simulated in order to determine from the comparison which value is the most probable for the Milky Way.

The result published in “The Astrophysical Journal” amounts to 960 billion times the mass of our Sun. It is thus in the range of earlier projections, which had come to values between 700 billion and two billion solar masses.

Ekta Patel’s team measured the angular momentum of nine of the Milky Way’s roughly 50 satellite galaxies. Without external action, the angular momentum does not change – unlike the speed of these galaxies, because they move around the Milky Way on elliptical orbits.

Since most large galaxies are orbited by smaller satellite galaxies, the method is also suitable for “weighing” other large star islands. So the investigation also supports earlier assumptions, according to which our large neighbor, the Andromeda galaxy, has more mass than our home galaxy.

Andrei Santov

Andrei, a sociologist by profession, born in Russia but currently located in UK, covers mostly European and Russia-related news for The Talking Democrat.