Chinese astronomers have calculated the "weight" of the Andromeda Galaxy. The reporter learned on the 5th that using the spectral data of the Guo Shoujing Telescope (LAMOST) and the existing observation results of the Andromeda Galaxy (M31), scientific researchers from Yunnan University and other units have constructed the largest catalog of Andromeda Galaxy objects in the world with radial velocity measurements.
Based on this, they successfully drew the rotation curve of the Andromeda Galaxy with the widest range of observations and the highest accuracy ever, and calculated that the mass of the Andromeda Galaxy is approximately 1.14 trillion times the mass of the sun. Relevant research results were published online in the British "Monthly Notices of the Royal Astronomical Society".
The Andromeda Galaxy is the closest large spiral galaxy to the Milky Way, about 2.5 million light-years from Earth. Among the Local Group of galaxies consisting of the Milky Way, Andromeda, etc., Andromeda is the only large dynamic system similar to the Milky Way that can be observed in complete detail. Therefore, the Andromeda Galaxy is an excellent example for studying the formation and evolution of galaxies.
"However, because the Andromeda Galaxy is far away from us, it is very difficult for astronomers to identify the celestial bodies within it. In addition, there is a lack of motion information of these celestial bodies. Therefore, accurately drawing the rotation curve of the Andromeda Galaxy is a very challenging task." Chen Bingqiu, co-corresponding author of the paper and professor at Yunnan University, told reporters.
This time, the research team collected 13,679 celestial objects in the Andromeda Galaxy with radial velocity measurements, and drew the rotation curve within 407,600 light-years from the center of the Andromeda Galaxy with an accuracy of 5%-20%. Research results show that the rotation curve of the Andromeda Galaxy maintains a constant value of about 220 kilometers per second on its galaxy disk, and gradually decreases outward to about 170 kilometers per second in the outer halo.
Mass is a fundamental physical property of a galaxy. Accurately measuring the mass of Andromeda is critical to understanding its material distribution, formation and evolution history, and role in the Local Group of galaxies. Based on this rotation curve, the research team constructed a mass model of Andromeda containing three components, gave the mass distribution of Andromeda, and calculated that the mass of Andromeda is approximately 1.14 trillion times the mass of the sun.
Chen Bingqiu said that this study provides a new understanding of the mass distribution of Andromeda and even general spiral galaxies, and is of great significance to further understanding the dynamic structure and formation evolution of spiral galaxies.