On April 20th, it was reported that Chinese scientists calculated the weight of the Milky Way galaxy, according to the National Astronomical Observatories of China (NAOC), part of the Chinese Academy of Sciences.
Based on the observation data from China’s Guo Shoujing Telescope (LAMOST) and the American APOGEE survey, Chinese astronomers have accurately measured the motion speeds of stars within a range of 16,000 to 81,000 light-years from the center of the Milky Way galaxy.
They estimated that the weight of the galaxy is about 805 billion times that of the sun. The related research results were published online in Astronomy and Astrophysics.
Measuring the mass of the Milky Way is a challenging problem, as there is no ready-made scale that can weigh this galaxy-sized “big guy”.
Measuring the rotation curve of the Milky Way, which is the velocity of stars at different distances from its center, is currently one of the commonly used methods for astronomers to measure its mass.
However, estimating the mass of the Milky Way using its rotation curve is not an easy task. It requires obtaining information on a group of iconic celestial bodies that are far from the center of the Milky Way, such as their precise distance from the center, proper motion and radial velocity,” said Huang Yang, corresponding author of the paper and associate professor at University of Chinese Academy of Sciences.
This time, researchers collected spectral data from over 250,000 bright red giants in the Milky Way galaxy from LAMOST and APOGEE sky survey data.
“These spectral data provide precise information on stellar atmospheric parameters, motion velocity, chemical element abundance and other parameters, providing good conditions for accurately measuring the rotation curve of the Milky Way,” Huang Yang stated.
Afterwards, the researchers selected about 54,000 thin disk stars in the Milky Way from these more than 250,000 bright red giants. They have information on radial velocity, proper motion and spectroscopic distance.
“On this basis, we constructed the Milky Way rotation curve within a range of 16,000 to 81,000 light-years from the center of the galaxy,” Huang said. Based on this rotation curve, researchers further constructed a mass model of the Milky Way and estimated its mass to be about 805 billion solar masses.
The research holds great significance and has received high praise from reviewers who stated, “This is presently the most accurate measurement of our galaxy’s rotation curve.”