Scientists determine more accurate weight of Milky Way

James Marshall
March 11, 2019

Using NASA's Hubble Space Telescope and the European Space Agency's Gaia satellite, a team of worldwide scientists determined the Milky Way (the galaxy that contains our solar system) weighs in at about 1.5 trillion solar masses.

That number is 1.5 trillion solar masses (within 129,000 light-years of the galactic center, to be specific).

Rather, most of its mass is locked up in dark matter, an invisible substance that, according to the space administration, "acts like scaffolding throughout the universe and keeps the stars in their galaxies".

Pervious estimates put the mass of the Milky Way ranging between 500 billion and three trillion times the mass of the Sun.

NASA used data from Hubble and Gaia to measure the three-dimensional movement of globular star clusters that each contain hundreds of thousands of stars.

"We were surprised that our value fell in the middle of the extensive range of previous estimates", Watkins explained. "So this value was on the high end of the most recent work".

Dark matter represented an issue, but researchers used a particular technique.

That tiny portion of weight also includes the big 4-million-solar-mass supermassive black hole at the center of the Milky Way.

The new mass estimate puts our galaxy on the beefier side, compared to other galaxies in the universe.

"One reason it's important to measure the Milky Way is that we live here, it's the closest galaxy we have", Watkins says in a report from The Guardian. NASA notes that the estimate of 1.5 trillion solar masses is typical of galaxies of the Milky Way's brightness.

The mass of the Milky Way is one of the most fundamental measurements astronomers can make about our galactic home.

"The more massive a galaxy, the faster its clusters move under the pull of its gravity", explains astrophysicist Wyn Evans of the University of Cambridge in Britain in the ESA statement. "However, we were able to also measure the sideways motion of the clusters, from which the total velocity, and consequently the galactic mass, can be calculated", Evans said.

In the ESA press release, study co-author Roeland van der Marel, an astronomer at the Space Telescope Science Institute in Baltimore, Maryland, said his team was able to "pin down the Milky Way's mass in a way that would be impossible without these two space telescopes", so this is a good example of scientists pooling their resources to produce research that wouldn't otherwise be achievable. Those clusters orbit near the center of our galaxy.

Data from the Gaia mission is key with measurements of these globular clusters extending up to 65,000 light-years away from Earth, while the observations from Hubble added data from globular clusters as far as 130,000 light-years from the planet.

If we compare the Milky Way to another galaxy, we can see that it is a bit heavier than a lot of them.

Other reports by Click Lancashire

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