Astronomers draw that conclusion based on observations from the Hubble space telescope and the Gaia satellite. Their findings can be read here.
It is not the first time that researchers try to estimate the mass of the Milky Way. Earlier estimates, however, varied greatly, from 500 billion to no less than 3 trillion solar masses. The fact that there are such big differences between previous estimates can be explained by the fact that researchers do not know how dark matter – responsible for about 90% of the mass of a galaxy – is distributed. “We can not directly observe dark matter,” says researcher Laura Watkins.
“This leads to the uncertainty that currently exists
the mass of the Milky Way is: you can not accurately measure something you can not see. “
Globular star clusters
But Watkins and colleagues have devised something on this. They studied the speed at which spherical star clusters move around the disk of our Milky Way. “The heavier a galaxy, the faster the clusters move under the influence of the gravity of that galaxy,” says researcher N. Wyn Evans.
“Most of the previous measurements only determined at what speed a globular cluster of stars moves towards us or away from us (…) But we were also able to measure the lateral movement of clusters and thus the complete speed and thus the mass of the galaxy. “
As mentioned, researchers used two data sets during this study: data collected by Gaia and data collected by Hubble. The former satellite was designed to accurately capture the movements of countless objects to the starry sky and studied tens of thousands of spherical star clusters that were cut off from the earth by up to 65,000 light-years. From the Hubble dataset, researchers fished data from spherical star clusters that were further removed from the earth. “By combining Gaia’s measurements of 34 spherical star clusters with measurements taken by Hubble of 12 globally-spaced spherical star clusters, we were able to determine the mass of the Milky Way in a way that would not have been possible without these two space telescopes,” says researcher Roeland P van der Marel.