591 high-speed stars were discovered by Chinese astronomers – 43 of them can even escape the galaxy

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With the Wide Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) and Gaia, a research team led by astronomers from the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) has found 591 high-speed stars, 43 of which can even escape from the galaxy.

Following the observation of the first high-speed star in 2005, the cumulative number of high-speed stars observed in 15 years by various telescopes is over 550. “The 591 high-speed stars discovered this time double the total number of high-speed stars discovered so far, bringing the total number to more than 1000,” said Dr. Yin-Bi Li, lead author of the report.

High-speed stars are a type of fast-moving star, and the galaxy may even avoid them. “Although rare in the Milky Way, high-speed stars with their unique kinematics can provide deep insights into a wide range of galactic science, from the central supermassive black hole to the distant galactic halo,” said NAOC co-author Prof. You-Jun Lu.

As described previously, with LAMOST and Gaia, these high-speed stars were discovered. LAMOST is China’s largest optical telescope, which has the highest spectral acquisition rate in the world and can observe approximately 4,000 single exposure celestial targets, and started daily surveys in 2012, establishing the world’s largest spectral database. Gaia is a space-based mission within the research program of the European Space Agency (ESA) that was launched in 2013, offering astrometric parameters for more than 1.3 billion sources, making it the largest database of astrometric parameters. “The two massive databases provide us with an unprecedented opportunity to find more high-speed stars, and we have succeeded,” said Prof.

A-Li Luo, co-author of this review, from NAOC.

The research team discovered, using kinematics and chemistry, that the 591 high-speed stars are inner halo stars. Their low metallicities imply that much of the stellar halo was produced as a result of dwarf galaxies’ accretion and tidal disturbance,”Their low metallicities suggest that most of the stellar halo formed as a result of accretion and tidal perturbation of dwarf galaxies,”

The detection of these high-speed stars informs us that, in the future, the combination of many large surveys will help to find more high-speed stars and other unusual stars that we can use to research our galaxy’s unresolved mystery.

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

Reference: 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, The Astrophysical Journal, 17 December 2020, ‘591 High-Velocity Stars in the Galactic Halo Selected from LAMOST DR7 and Gaia DR2.’ 10.3847/1538-4365/abc16ee DOI:

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