The latest "weight" of the galaxy is here! On the 20th, the reporter learned from the National Astronomical Observatory of the Chinese Academy of Sciences that based on the observation data of China's Guo Shoujing Telescope (LAMOST) and the American APOGEE Sky Survey, Chinese astronomers accurately measured the speed of star motion within 1,6 light to 8,1 light years from the center of the Milky Way, and estimated that the "weight" of the Milky Way is about 8050 billion solar masses. The research results were published online in the Journal of Astrophysics.
Measuring the mass of the Milky Way is a challenging problem, and there is no ready-made scale that can weigh this galaxy-level "big fat man". Measuring the rotation curve of the Milky Way, that is, the speed of stars at different distances from the center of the Milky Way, is one of the common methods astronomers use to measure the mass of the Milky Way.
"However, estimating the mass of the Milky Way using the rotation curve of the Milky Way is not an easy task, and it is necessary to obtain information on a number of iconic objects farther from the center of the Milky Way, such as the precise distance, proper propulsion speed and apparent velocity of the celestial objects from the center of the Milky Way." Huang Zang, the corresponding author of the paper and associate professor at the University of Chinese Academy of Sciences, said.
This time, the researchers collected spectral data from more than 25,<> bright red giants in the Milky Way from LAMOST and APOGEE sky survey data. "These spectral data provide accurate parameter information such as stellar atmospheric parameters, motion speeds, and abundances of chemical elements, providing good conditions for accurate measurement of the rotation curve of the Milky Way." Huang said.
Later, the researchers selected about 25,54000 thin-disk stars of the Milky Way from these more than 1,6 bright red giants, which have information on apparent velocity, proper motion speed and spectral distance. "On this basis, we constructed the rotation curve of the Milky Way within 8,1 light-years to 8050,<> light-years from the center of the Milky Way." Based on this rotation curve, the researchers further built a mass model of the Milky Way, estimating that the mass of the Milky Way is about <> billion solar masses, Huang said.
Huang said that this study has drawn the most accurate rotation curve of the Milky Way, which provides a crucial constraint for measuring basic physical quantities such as the total mass of the Milky Way and the density of dark matter near the sun, which is of great significance for searching for dark matter particles and understanding the distribution of dark matter in the Milky Way. The paper's reviewers also spoke highly of the results: "This is the best measurement of the rotation curve of the Milky Way so far." ”
◎ Science and Technology Daily reporter Lu Chengkuan