Identification of Blue Horizontal-branch Stars Using Synthetic SkyMapper Colors from Gaia XP Spectra
Blue horizontal-branch (BHB) stars are ideal tracers for mapping the structure of the Galactic stellar halo. Traditionally, BHB sample stars are built from large-scale spectroscopic surveys utilizing their spectral features; however, the resulting sample sizes have been quite limited. In this paper,...
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IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal Supplement Series |
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| Online Access: | https://doi.org/10.3847/1538-4365/add5f8 |
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| author | Guozhen Hu Yang Huang Wenyuan Cui Tao Wang Kai Xiao Ruifeng Shi Jie Ju Bowen Huang Chunyan Li Zhicun Liu Xiaolong Wang Changqing Luo |
| author_facet | Guozhen Hu Yang Huang Wenyuan Cui Tao Wang Kai Xiao Ruifeng Shi Jie Ju Bowen Huang Chunyan Li Zhicun Liu Xiaolong Wang Changqing Luo |
| author_sort | Guozhen Hu |
| collection | DOAJ |
| description | Blue horizontal-branch (BHB) stars are ideal tracers for mapping the structure of the Galactic stellar halo. Traditionally, BHB sample stars are built from large-scale spectroscopic surveys utilizing their spectral features; however, the resulting sample sizes have been quite limited. In this paper, we construct a catalog of BHB stars based on synthetic colors ( u − v ) _0 and ( g − i ) _0 in SkyMapper photometric systems, which are convolved from Gaia XP spectra. A total of 49,733 BHB stars are selected from nearly the entire sky (excluding regions of low Galactic latitudes ∣ b ∣ ≤ 8 ^∘ with heavy reddening), with a completeness and purity exceeding 90%. Using member stars of globular clusters with precise distance determinations, we carefully calibrate the relationship between the g -band absolute magnitude and ( g − i ) _0 , achieving a precision of 0.11 mag, which corresponds to a 5% uncertainty in distance. This relation is applied to derive distances for all BHB stars in the constructed sample. Given the current capabilities of Gaia XP observations, the constructed BHB sample is primarily located within 20 kpc, enabling detailed mapping of the inner stellar halo. To extend this depth to the outer halo or even the edge of our Galaxy, we explore the potential of the Chinese Space Station Telescope (CSST) and its broadband photometry for detecting BHB stars. Using mock data from synthetic spectra, we find that it is feasible to distinguish BHB stars from blue stragglers stars using CSST near-ultraviolet band ( u ) photometry. Thanks to the deep limiting magnitude of CSST, its data will provide a groundbreaking perspective on our Galaxy, particularly regarding the outer halo, in an unprecedented volume. |
| format | Article |
| id | doaj-art-3a4b7d8dd08145c6835a17d9f09afe8d |
| institution | Kabale University |
| issn | 0067-0049 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal Supplement Series |
| spelling | doaj-art-3a4b7d8dd08145c6835a17d9f09afe8d2025-08-20T03:44:51ZengIOP PublishingThe Astrophysical Journal Supplement Series0067-00492025-01-0127826210.3847/1538-4365/add5f8Identification of Blue Horizontal-branch Stars Using Synthetic SkyMapper Colors from Gaia XP SpectraGuozhen Hu0https://orcid.org/0000-0003-1828-5318Yang Huang1https://orcid.org/0000-0003-3250-2876Wenyuan Cui2https://orcid.org/0000-0003-1359-9908Tao Wang3Kai Xiao4https://orcid.org/0000-0001-8424-1079Ruifeng Shi5Jie Ju6Bowen Huang7https://orcid.org/0000-0002-1259-0517Chunyan Li8https://orcid.org/0000-0003-2021-4818Zhicun Liu9https://orcid.org/0000-0001-5314-2924Xiaolong Wang10https://orcid.org/0000-0003-2536-3142Changqing Luo11https://orcid.org/0000-0001-8799-480XDepartment of Physics, Hebei Normal University , Shijiazhuang 050024, People’s Republic of China ; cuiwenyuan@hebtu.edu.cn; Guo Shoujing Institute for Astronomy, Hebei Normal University , Shijiazhuang 050024, People’s Republic of China; Hebei Key Laboratory of Photophysics Research and Application , Shijiazhuang 050024, People’s Republic of ChinaSchool of Astronomy and Space Science, University of Chinese Academy of Sciences , Beijing 100049, People’s Republic of China ; huangyang@ucas.ac.cn; National Astronomical Observatories, Chinese Academy of Sciences , Beijing 100012, People’s Republic of China; Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University , Beijing, 102206, People’s Republic of ChinaDepartment of Physics, Hebei Normal University , Shijiazhuang 050024, People’s Republic of China ; cuiwenyuan@hebtu.edu.cn; Guo Shoujing Institute for Astronomy, Hebei Normal University , Shijiazhuang 050024, People’s Republic of ChinaSouth-Western Institute for Astronomy Research, Yunnan University , Kunming, 650500, People’s Republic of ChinaSchool of Astronomy and Space Science, University of Chinese Academy of Sciences , Beijing 100049, People’s Republic of China ; huangyang@ucas.ac.cnSchool of Astronomy and Space Science, University of Chinese Academy of Sciences , Beijing 100049, People’s Republic of China ; huangyang@ucas.ac.cnDepartment of Physics, Hebei Normal University , Shijiazhuang 050024, People’s Republic of China ; cuiwenyuan@hebtu.edu.cn; School of Sciences, Hebei University of Science and Technology , Shijiazhuang 050018, People’s Republic of ChinaInstitute for Frontiers in Astronomy and Astrophysics, Beijing Normal University , Beijing, 102206, People’s Republic of China; School of Physics and Astronomy, Beijing Normal University , No. 19 Xinjiekouwai Street, Haidian District, Beijing, 100875, People’s Republic of ChinaSchool of Physics and Astronomy, China West Normal University , No. 1 Shida Road, Nanchong 637002, People’s Republic of ChinaDepartment of Physics, Hebei Normal University , Shijiazhuang 050024, People’s Republic of China ; cuiwenyuan@hebtu.edu.cn; Guo Shoujing Institute for Astronomy, Hebei Normal University , Shijiazhuang 050024, People’s Republic of China; Hebei Key Laboratory of Photophysics Research and Application , Shijiazhuang 050024, People’s Republic of ChinaDepartment of Physics, Hebei Normal University , Shijiazhuang 050024, People’s Republic of China ; cuiwenyuan@hebtu.edu.cn; Guo Shoujing Institute for Astronomy, Hebei Normal University , Shijiazhuang 050024, People’s Republic of China; Hebei Advanced Thin Films Laboratory , Shijiazhuang 050024, People’s Republic of ChinaNational Astronomical Observatories, Chinese Academy of Sciences , Beijing 100012, People’s Republic of ChinaBlue horizontal-branch (BHB) stars are ideal tracers for mapping the structure of the Galactic stellar halo. Traditionally, BHB sample stars are built from large-scale spectroscopic surveys utilizing their spectral features; however, the resulting sample sizes have been quite limited. In this paper, we construct a catalog of BHB stars based on synthetic colors ( u − v ) _0 and ( g − i ) _0 in SkyMapper photometric systems, which are convolved from Gaia XP spectra. A total of 49,733 BHB stars are selected from nearly the entire sky (excluding regions of low Galactic latitudes ∣ b ∣ ≤ 8 ^∘ with heavy reddening), with a completeness and purity exceeding 90%. Using member stars of globular clusters with precise distance determinations, we carefully calibrate the relationship between the g -band absolute magnitude and ( g − i ) _0 , achieving a precision of 0.11 mag, which corresponds to a 5% uncertainty in distance. This relation is applied to derive distances for all BHB stars in the constructed sample. Given the current capabilities of Gaia XP observations, the constructed BHB sample is primarily located within 20 kpc, enabling detailed mapping of the inner stellar halo. To extend this depth to the outer halo or even the edge of our Galaxy, we explore the potential of the Chinese Space Station Telescope (CSST) and its broadband photometry for detecting BHB stars. Using mock data from synthetic spectra, we find that it is feasible to distinguish BHB stars from blue stragglers stars using CSST near-ultraviolet band ( u ) photometry. Thanks to the deep limiting magnitude of CSST, its data will provide a groundbreaking perspective on our Galaxy, particularly regarding the outer halo, in an unprecedented volume.https://doi.org/10.3847/1538-4365/add5f8Milky Way stellar haloHorizontal branch stars |
| spellingShingle | Guozhen Hu Yang Huang Wenyuan Cui Tao Wang Kai Xiao Ruifeng Shi Jie Ju Bowen Huang Chunyan Li Zhicun Liu Xiaolong Wang Changqing Luo Identification of Blue Horizontal-branch Stars Using Synthetic SkyMapper Colors from Gaia XP Spectra The Astrophysical Journal Supplement Series Milky Way stellar halo Horizontal branch stars |
| title | Identification of Blue Horizontal-branch Stars Using Synthetic SkyMapper Colors from Gaia XP Spectra |
| title_full | Identification of Blue Horizontal-branch Stars Using Synthetic SkyMapper Colors from Gaia XP Spectra |
| title_fullStr | Identification of Blue Horizontal-branch Stars Using Synthetic SkyMapper Colors from Gaia XP Spectra |
| title_full_unstemmed | Identification of Blue Horizontal-branch Stars Using Synthetic SkyMapper Colors from Gaia XP Spectra |
| title_short | Identification of Blue Horizontal-branch Stars Using Synthetic SkyMapper Colors from Gaia XP Spectra |
| title_sort | identification of blue horizontal branch stars using synthetic skymapper colors from gaia xp spectra |
| topic | Milky Way stellar halo Horizontal branch stars |
| url | https://doi.org/10.3847/1538-4365/add5f8 |
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