@article{ac8fad022ace4340af7960c54fff81b4,
title = "Ultracool dwarfs identified using spectra in LAMOST DR7",
abstract = " In this work, we identify 734 ultracool dwarfs with a spectral type of M6 or later, including one L0. Of this sample, 625 were studied spectroscopically for the first time. All of these ultracool dwarfs are within 360~pc, with a \textit{Gaia} G magnitude brighter than ~19.2 mag. By studying the spectra and checking their stellar parameters (Teff, logg, and [FeH] derived with the LAMOST pipeline, we found their cool red nature and their metallicity to be consistent with the nature of Galactic thin-disk objects. Furthermore, 77 of them show lithium absorption lines at 6708A, further indicating their young ages and substellar nature. Kinematics obtained through LAMOST radial velocities, along with the proper motion and parallax data from Gaia EDR3, also suggest that the majority of our targets are thin-disk objects. Kinematic ages were estimated through the relationship between the velocity dispersion and the average age for a certain population. Moreover, we identified 35 binaries, with 6 of them reported as binaries for the first time. ",
keywords = "Binaries: visual, Brown dwarfs, Stars: late-type, Stars: low-mass, Surveys",
author = "You-Fen Wang and A-Li Luo and Wen-Ping Chen and Jones, {Hugh R. A.} and Bing Du and Yin-Bi Li and Shuo Zhang and Zhong-Rui Bai and Xiao Kong and Yan-Xin Guo",
note = "{\textcopyright} ESO 2022. This is the author{\textquoteright}s accepted version of the work, which was originally published at https://doi.org/10.1051/0004-6361/202142009 Funding Information: Acknowledgements. We thank Mr. Shih-Yun Tang for the idea of binarity study and help with Gaia data usage. We thank Dr. Richard L. Smart for a very useful discussion on the kinematic study of nearby cool objects. This work is supported by the National Key R&D Program of China (No. 2019YFA0405502), National Science Foundation of China (No. U1931209), Chinese Space Station Telescope (CSST) pre-research projects of Key Problems in Binaries and Chemical Evolution of the Milky Way and its Nearby Galaxies. W. P. C. acknowledges the financial support from the grant MOST 106-2112-M-008-005-MY3. H. R. A. J. acknowledges support from a CAS PIFI Grant No. 2020VMA0033 and UK STFC grant ST/R006598/1. Y. X. G. acknowledges the National Science Foundation of China (Nos. U2031137). Y. B. L. acknowledges the science research grants from the China Manned Space Project with NO.CMS-CSST-2021-A10, NO.CMS-CSST-2021-A08 and NO.CMS-CSST-2021-B05. Guoshoujing Telescope (the Large Sky Area Multi-Object Fiber Spectroscopic Telescope LAM-OST) is a National Major Scientific Project built by the Chinese Academy of Sciences. Funding for the project has been provided by the National Development and Reform Commission. LAMOST is operated and managed by the National Astronomical Observatories, Chinese Academy of Sciences. Funding Information: We thank Mr. Shih-Yun Tang for the idea of binarity study and help with Gaia data usage. We thank Dr. Richard L. Smart for a very useful discussion on the kinematic study of nearby cool objects. This work is supported by the National Key R&D Program of China (No. 2019YFA0405502), National Science Foundation of China (No. U1931209), Chinese Space Station Telescope (CSST) pre-research projects of Key Problems in Binaries and Chemical Evolution of the Milky Way and its Nearby Galaxies. W. P. C. acknowledges the financial support from the grant MOST 106-2112-M-008-005-MY3. H. R. A. J. acknowledges support from a CAS PIFI Grant No. 2020VMA0033 and UK STFC grant ST/R006598/1. Y. X. G. acknowledges the National Science Foundation of China (Nos. U2031137). Y. B. L. acknowledges the science research grants from the China Manned Space Project with NO.CMS-CSST-2021-A10, NO.CMS-CSST-2021-A08 and NO.CMS-CSST-2021-B05. Guoshoujing Telescope (the Large Sky Area Multi-Object Fiber Spectroscopic Telescope LAMOST) is a National Major Scientific Project built by the Chinese Academy of Sciences. Funding for the project has been provided by the National Development and Reform Commission. LAMOST is operated and managed by the National Astronomical Observatories, Chinese Academy of Sciences. Publisher Copyright: {\textcopyright} ESO 2022.",
year = "2022",
month = apr,
day = "5",
doi = "10.1051/0004-6361/202142009",
language = "English",
volume = "660",
journal = "Astronomy & Astrophysics",
issn = "0004-6361",
publisher = "EDP Sciences",
}