Systematic Search for Blue Hypervelocity Stars from LAMOST Survey

Hypervelocity stars (HVSs) represent a unique class of objects capable of escaping the gravitational pull of the Milky Way due to extreme acceleration events, such as close encounters with the supermassive black hole at the Galactic center (GC), supernova explosions in binary systems, or multibody d...

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Main Authors: Yongkang Sun, Yang Huang, Jifeng Liu, Haozhu Fu, Huawei Zhang, Yinbi Li, Cuihua Du, Jianrong Shi, Xiao Kong
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/adcebe
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author Yongkang Sun
Yang Huang
Jifeng Liu
Haozhu Fu
Huawei Zhang
Yinbi Li
Cuihua Du
Jianrong Shi
Xiao Kong
author_facet Yongkang Sun
Yang Huang
Jifeng Liu
Haozhu Fu
Huawei Zhang
Yinbi Li
Cuihua Du
Jianrong Shi
Xiao Kong
author_sort Yongkang Sun
collection DOAJ
description Hypervelocity stars (HVSs) represent a unique class of objects capable of escaping the gravitational pull of the Milky Way due to extreme acceleration events, such as close encounters with the supermassive black hole at the Galactic center (GC), supernova explosions in binary systems, or multibody dynamical interactions. Finding and studying HVSs are crucial to exploring these ejection mechanisms, characterizing central black holes, probing the GC environment, and revealing the distribution of dark matter in our Galaxy. The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) spectroscopic surveys have so far identified four B-type unbound HVSs. To expand this sample with the second-phase LAMOST survey that started in 2018, we conducted a systematic search for early-type HVSs using the LAMOST Data Release 10. We identified 125 early-type high-velocity candidates with total velocities exceeding 300 km s ^−1 . Among them, we report 10 new unbound B- and A-type HVS candidates (designated LAMOST-HVS 5 through LAMOST-HVS 14), tripling the number of unbound HVSs previously identified by LAMOST. Kinematic analyses suggest that these newly discovered HVS candidates likely originated either from the GC or via dynamical interactions. Future high-resolution follow-up observations promise to refine the stellar parameters, distances, and elemental abundances of these candidates, thereby providing deeper insights into their origins and broadening their potential applications across astrophysics.
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spelling doaj-art-914bbf7a88614a4eabf40b608548b87c2025-08-20T03:26:00ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0198612210.3847/1538-4357/adcebeSystematic Search for Blue Hypervelocity Stars from LAMOST SurveyYongkang Sun0https://orcid.org/0000-0002-3935-2666Yang Huang1https://orcid.org/0000-0003-3250-2876Jifeng Liu2https://orcid.org/0000-0002-2874-2706Haozhu Fu3https://orcid.org/0009-0002-4542-8046Huawei Zhang4https://orcid.org/0000-0002-7727-1699Yinbi Li5https://orcid.org/0000-0001-7607-2666Cuihua Du6https://orcid.org/0000-0002-3954-617XJianrong Shi7https://orcid.org/0000-0002-0349-7839Xiao Kong8https://orcid.org/0000-0001-8011-8401National Astronomical Observatories, Chinese Academy of Sciences , Beijing 100101, People’s Republic of China ; huangyang@ucas.ac.cn; School of Astronomy and Space Science, University of Chinese Academy of Sciences , Beijing 100049, People’s Republic of ChinaNational Astronomical Observatories, Chinese Academy of Sciences , Beijing 100101, People’s Republic of China ; huangyang@ucas.ac.cn; School of Astronomy and Space Science, University of Chinese Academy of Sciences , Beijing 100049, People’s Republic of ChinaNational Astronomical Observatories, Chinese Academy of Sciences , Beijing 100101, People’s Republic of China ; huangyang@ucas.ac.cn; School of Astronomy and Space Science, University of Chinese Academy of Sciences , Beijing 100049, People’s Republic of ChinaDepartment of Astronomy, Peking University , Beijing, 100871, People’s Republic of China; Kavli Institute for Astronomy and Astrophysics, Peking University , Beijing, 100871, People’s Republic of ChinaDepartment of Astronomy, Peking University , Beijing, 100871, People’s Republic of China; Kavli Institute for Astronomy and Astrophysics, Peking University , Beijing, 100871, People’s Republic of ChinaNational Astronomical Observatories, Chinese Academy of Sciences , Beijing 100101, People’s Republic of China ; huangyang@ucas.ac.cn; School of Astronomy and Space Science, University of Chinese Academy of Sciences , Beijing 100049, People’s Republic of ChinaSchool of Astronomy and Space Science, University of Chinese Academy of Sciences , Beijing 100049, People’s Republic of ChinaNational Astronomical Observatories, Chinese Academy of Sciences , Beijing 100101, People’s Republic of China ; huangyang@ucas.ac.cn; School of Astronomy and Space Science, University of Chinese Academy of Sciences , Beijing 100049, People’s Republic of ChinaNational Astronomical Observatories, Chinese Academy of Sciences , Beijing 100101, People’s Republic of China ; huangyang@ucas.ac.cnHypervelocity stars (HVSs) represent a unique class of objects capable of escaping the gravitational pull of the Milky Way due to extreme acceleration events, such as close encounters with the supermassive black hole at the Galactic center (GC), supernova explosions in binary systems, or multibody dynamical interactions. Finding and studying HVSs are crucial to exploring these ejection mechanisms, characterizing central black holes, probing the GC environment, and revealing the distribution of dark matter in our Galaxy. The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) spectroscopic surveys have so far identified four B-type unbound HVSs. To expand this sample with the second-phase LAMOST survey that started in 2018, we conducted a systematic search for early-type HVSs using the LAMOST Data Release 10. We identified 125 early-type high-velocity candidates with total velocities exceeding 300 km s ^−1 . Among them, we report 10 new unbound B- and A-type HVS candidates (designated LAMOST-HVS 5 through LAMOST-HVS 14), tripling the number of unbound HVSs previously identified by LAMOST. Kinematic analyses suggest that these newly discovered HVS candidates likely originated either from the GC or via dynamical interactions. Future high-resolution follow-up observations promise to refine the stellar parameters, distances, and elemental abundances of these candidates, thereby providing deeper insights into their origins and broadening their potential applications across astrophysics.https://doi.org/10.3847/1538-4357/adcebeHypervelocity starsEarly-type starsSky surveysRadial velocity
spellingShingle Yongkang Sun
Yang Huang
Jifeng Liu
Haozhu Fu
Huawei Zhang
Yinbi Li
Cuihua Du
Jianrong Shi
Xiao Kong
Systematic Search for Blue Hypervelocity Stars from LAMOST Survey
The Astrophysical Journal
Hypervelocity stars
Early-type stars
Sky surveys
Radial velocity
title Systematic Search for Blue Hypervelocity Stars from LAMOST Survey
title_full Systematic Search for Blue Hypervelocity Stars from LAMOST Survey
title_fullStr Systematic Search for Blue Hypervelocity Stars from LAMOST Survey
title_full_unstemmed Systematic Search for Blue Hypervelocity Stars from LAMOST Survey
title_short Systematic Search for Blue Hypervelocity Stars from LAMOST Survey
title_sort systematic search for blue hypervelocity stars from lamost survey
topic Hypervelocity stars
Early-type stars
Sky surveys
Radial velocity
url https://doi.org/10.3847/1538-4357/adcebe
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