Chinese astronomers discover 591 stars at high speed – 43 of them may even escape the galaxy

A research team, led by astronomers from the Chinese Academy of Sciences (NAOC) National Astronomical Observatories, discovered 591 high-speed stars from the Large Sky Area Multi-Object Spectroscopic Fiber Telescope (LAMOST) and Gaia, and 43 of them can even escape. of the galaxy. After the discovery of the first high-speed star in 2005, there are a total of over 550 high-speed stars that have been found with multiple telescopes in 15 years. “The 591 high-speed stars discovered this time have doubled the total number of previously discovered high-speed stars, bringing the total number to over 1,000,” said Dr. Yin-Bi Li, the lead author of the research. .

High speed stars are sort of fast moving stars and can even escape from the galaxy. “Although rare in the Milky Way, high-speed stars, with unique kinematics, can provide in-depth insight into a wide range of galactic sciences, from the central supermassive black hole to the distant galactic halo, ”said Professor You-Jun Lu of NAOC, co-author of this research.

As mentioned above, these high speed stars were discovered with LAMOST and Gaia. LAMOST is China’s largest optical telescope, which has the highest spectral acquisition rate in the world and can observe around 4000 celestial targets in a single exposure, and it started the regular surveys in 2012, which established the most large spectra database in the world. Gaia is a space mission under the European Space Agency’s (ESA) science program launched in 2013, and it has provided astrometric parameters for more than 1.3 billion sources, which is the largest database of astrometric parameters. “The two massive databases give us an unprecedented opportunity to find more stars at high speed, and we did,” said NAOC Professor A-Li Luo, co-author of the research.

From kinematics and chemistry, the research team discovered that the 591 high-speed stars are internally halo stars. “Their low metallities indicate that most of the stellar halo formed as a result of accretion and disturbance of the tides of dwarf galaxies,” said Professor Gang Zhao of NAOC, co-author of this research.

The discovery of these high-speed stars tells us that the combination of several large surveys in the future will help us discover more high-speed stars and other rare stars, which will be used to investigate the unsolved mystery of our galaxy.

This work was recently published online in The Astrophysical Journal Supplement Series.

Reference: “591 high speed stars in the galactic halo selected from among 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