591 high speed stars’ positions and orbits. Credit: Kong Xiao of NAOC
A research study group, led by astronomers from National Astronomical Observatories of Chinese Academy of Sciences (NAOC), has actually found 591 high speed stars from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) and Gaia, and 43 of them can even get away from the Galaxy. After the very first high speed star was found in 2005, there remain in overall of over 550 high speed stars have actually been discovered with numerous telescopes in 15 years. “The 591 high velocity stars discovered this time doubled the total number of high velocity stars previously discovered, bringing the total number exceeding 1000,” stated Dr. Yin-Bi Li, the lead author of the research study.
High speed stars are type of fast-moving stars, and they can even get away from the Galaxy. “Though unusual in the Milky Way, high speed stars, with special kinematics, can offer deep insight into a vast array of Galactic science, from the main supermassive great void to far-off Galactic halo,” stated Prof. You-Jun Lu from NAOC, co-author of this research study.
As pointed out above, these high speed stars were found with LAMOST and Gaia. LAMOST is the biggest optical telescope in China, which has the greatest spectral acquisition rate on the planet and can observe about 4,000 celestial targets in one single direct exposure, and it started the routine studies in 2012, which developed the biggest spectra database on the planet. Gaia is a space-based objective in the science program of the European Space Agency (ESA) released in 2013, and it supplied astrometric criteria for over 1.3 billion sources, which is the biggest database of astrometric criteria. “The two massive databases provide us unprecedented opportunity to find more high velocity stars, and we did it,” stated Prof. A-Li Luo from NAOC, co-author of this research study.
From the kinematics and chemistries, research study group discovered that the 591 high speed stars are inner halo stars. “Their low metallicities indicate that the bulk of the stellar halo formed as a consequence of the accretion and tidal disruption of dwarf galaxies,” stated Prof. Gang Zhao from NAOC, co-author of this research study.
The discovery of these high speed stars informs us that the mix of numerous big studies in the future will assist us to find more high speed stars and other unusual stars, which will be utilized to study the unsolved secret about our Galaxy.
This work has actually been just recently released online in The Astrophysical Journal Supplement Series.
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, 17 December 2020, The Astrophysical Journal.
DOI: 10.3847/1538-4365/abc16e
