591 high-velocity stars’ positions and orbits. Credit: NAOC’s Kong Xiao
A research team led by astronomers from the National Astronomical Observatories of Chinese Academy of Sciences (NAOC) has discovered 591 high-speed stars of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) and Gaia, and 43 of them may even escape from the Milky Way. After the first high-velocity star was discovered in 2005, a total of more than 550 high-velocity stars with multiple telescopes were found in 15 years. “The 591 high-velocity stars discovered this time have doubled the total number of high-velocity stars previously discovered, exceeding the total number more than 1,000,” said Dr. Yin-Bi Li, the lead author of the research, said.
High-velocity stars are fast-moving stars, and they can even escape from the Milky Way. ‘Although rare in the Milky Wayhigh stars with unique kinematics, can provide deep insight into a wide range of Galactic sciences, from the central supermassive black hole to a distant Galactic halo, ”said prof. You-Jun Lu of NAOC, co-author of this research, said.
As mentioned above, these high-velocity stars were discovered with LAMOST and Gaia. LAMOST is the largest optical telescope in China, with the highest spectrum acquisition rate in the world and can observe approximately 4,000 sky targets in a single exposure, and it started in 2012 with the regular surveys, which set up the largest spectrum database in the world. Gaia is a space-based mission in the European Space Agency’s (ESA) scientific program launched in 2013, providing astrometric parameters for more than 1.3 billion sources, which is the largest database of astrometric parameters. “The two massive databases offer us an unprecedented opportunity to find high-velocity stars, and we did,” said prof. A-Li Luo of NAOC, co-author of this research, said.
From the kinematics and chemicals, the research team found that the 591 high-velocity stars are inner rays. “Their low metallicity indicates that most of the star’s halo is formed due to the growth and tidal disturbance of dwarf systems,” said prof. Gang Zhao of NAOC, co-author of this research, said.
The discovery of these high-velocity stars tells us that the combination of multiple large-scale surveys in the future will help us discover more high-velocity stars and other rare stars, which will be used to study the unsolved mystery of our Milky Way.
This work was recently published online in The Series of Astrophysical Journal Supplements.
Reference: “591 High-velocity Stars in the Galactic Halo Selected from LAMOST DR7 and Gaia DR2” by Yin-Bi Li, A-Li Luo, You-Jun Lu, Xue-Sen Zhang, Jiao Li, Rui Wang, Fang Zuo, Maosheng Xiang, Yuan-Sen Ting, Tommaso Marchetti, Shuo Li, You-Fen Wang, Shuo Zhang, Kohei Hattori, Yong-Heng Zhao, Hua-Wei Zhang and Gang Zhao, December 17, 2020, The Astrophysical Journal.
DOI: 10.3847 / 1538-4365 / abc16e