Using data from NASA’s Hubble Space Telescope and the European Space Agency’s Gaia satellite, astronomers have come up with one of the most accurate measurements of mass of the Milky Way galaxy.
While previous research dating back several decades provided estimates for our galaxy’s mass, ranging between 500 billion to three trillion solar masses, according to the latest measurements, Milky Way weighs about 1.5 trillion solar masses (one solar mass is the mass of our Sun).
The measurement includes all the stars and planets, dust and gas, as well as the four-million-solar-mass supermassive black hole at the center.
“We want to know the mass of the Milky Way more accurately so that we can put it into a cosmological context and compare it to simulations of galaxies in the evolving universe,” said Roeland van der Marel of the Space Telescope Science Institute (STScI) in Baltimore, Maryland.
To weigh the galaxy, the team augmented Gaia measurements for 34 globular clusters out to 65,000 light-years, with Hubble measurements of 12 clusters out to 130,000 light-years that were obtained from images taken over a 10-year period.
They also measured the three-dimensional movement of globular star clusters – isolated spherical islands each containing hundreds of thousands of stars each that orbit the center of our galaxy.
The more massive a galaxy, the faster its globular clusters move under the pull of gravity, according to a forthcoming paper in The Astrophysical Journal.
The new mass estimate puts our galaxy on the beefier side, compared to other galaxies in the universe. The lightest galaxies are around a billion solar masses, while the heaviest are 30 trillion, or 30,000 times more massive.
The Milky Way, the galaxy which contains Earth’s solar system, is home to up to 400 billion stars and an estimated 100 billion planets.