New estimate shows the Milky Way weighs half as much as previously thought

Researchers from the Chinese Academy of Sciences used data from the APOGEE and LAMOST sky surveys.

ground-based telescopes, and GAIA, collectedspace observatory of the European Space Agency, to assess key parameters of the Milky Way. The analysis showed that the mass of our Galaxy is approximately 805 billion solar masses. This is almost two times less than the previous estimate.

Scientists collected data from 254,882 bright redsgiants - large stars with high luminosity, formed in the process of evolution from stars of medium mass. Astrophysicists used a large dataset to use machine learning to accurately measure the Milky Way's rotation curve from 16,000 to 81,000 light-years from the center of the Galaxy. The rotation curve is a function that describes the dependence of the orbital velocity of stars and gas in a galaxy on the distance to its center.

Based on astrophysics rotation curve estimationcreated a model for the mass of the Milky Way. The analysis showed that the mass of the Galaxy is approximately 805 billion times greater than the mass of the Sun, and the density of dark matter in the vicinity of our star is approximately 0.39 GeV/cm³.

In 2019, a group of American scientists fromThe Space Telescope Science Institute (STScI) used data on the three-dimensional motion of the Milky Way's globular clusters to estimate its mass. Calculations carried out in this study gave an estimate of 1.5 trillion solar masses.

For their assessment, Chinese astrophysicistsused the largest set of stellar data for such studies. However, the 250,000 stars are still a relatively small part of the Galaxy, which is estimated to contain at least 100 billion stars of various masses. Further research will help improve the accuracy of the measurements.

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On the cover: an artistic illustration of the Milky Way. Image: NASA/JPL-Caltech