An Old, Low-mass, Metal-poor Hypervelocity Star Candidate Consistent with a Galactic Center Origin
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| Autores principales: | , , , , , , |
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| Formato: | Preprint |
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2026
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| _version_ | 1866918499330293760 |
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| author | Deng, Shunhong Huang, Yang Fu, Haozhu Sun, Yongkang Feng, Qikang Chen, Guoyang Zhang, Huawei |
| author_facet | Deng, Shunhong Huang, Yang Fu, Haozhu Sun, Yongkang Feng, Qikang Chen, Guoyang Zhang, Huawei |
| contents | We report the discovery of DESI-HVS1, a hypervelocity star (HVS) candidate identified from DESI DR1 spectroscopy and Gaia DR3 astrometry. DESI-HVS1 is an old, low-mass, metal-poor F-type star with a mass of $0.8\,M_\odot$, an age of $\sim14.1$~Gyr, and $\mathrm{[Fe/H]}=-1.6$. It is located at a heliocentric distance of $3.77^{+0.39}_{-0.36}$~kpc and has a Galactocentric total velocity of $523^{+46}_{-47}\,\mathrm{km\,s^{-1}}$, marginally exceeding the local escape speed, corresponding to an unbound probability of $P_{\rm ub} \sim 50\%$. Backward orbit integrations show that DESI-HVS1 had a closest approach to the Galactic center (GC) of $0.40^{+0.23}_{-0.11}\,\mathrm{kpc}$, with a velocity of $682^{+22}_{-35}\,\mathrm{km\,s^{-1}}$ and a flight time of $12.89^{+0.92}_{-0.74}\,\mathrm{Myr}$. The reconstructed orbit exhibits a clear perigalactic turning point and only a single crossing of the Galactic midplane ($P_{\rm cross} > 0.95$). These properties suggest that DESI-HVS1 is most naturally explained by the Hills mechanism, although alternative scenarios cannot be entirely ruled out. Its discovery provides the first strong evidence for an old, low-mass HVS candidate consistent with a GC origin, indicating that the apparent dominance of young, massive GC-origin HVSs is likely a consequence of observational selection effects. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2604_21646 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | An Old, Low-mass, Metal-poor Hypervelocity Star Candidate Consistent with a Galactic Center Origin Deng, Shunhong Huang, Yang Fu, Haozhu Sun, Yongkang Feng, Qikang Chen, Guoyang Zhang, Huawei Astrophysics of Galaxies Solar and Stellar Astrophysics We report the discovery of DESI-HVS1, a hypervelocity star (HVS) candidate identified from DESI DR1 spectroscopy and Gaia DR3 astrometry. DESI-HVS1 is an old, low-mass, metal-poor F-type star with a mass of $0.8\,M_\odot$, an age of $\sim14.1$~Gyr, and $\mathrm{[Fe/H]}=-1.6$. It is located at a heliocentric distance of $3.77^{+0.39}_{-0.36}$~kpc and has a Galactocentric total velocity of $523^{+46}_{-47}\,\mathrm{km\,s^{-1}}$, marginally exceeding the local escape speed, corresponding to an unbound probability of $P_{\rm ub} \sim 50\%$. Backward orbit integrations show that DESI-HVS1 had a closest approach to the Galactic center (GC) of $0.40^{+0.23}_{-0.11}\,\mathrm{kpc}$, with a velocity of $682^{+22}_{-35}\,\mathrm{km\,s^{-1}}$ and a flight time of $12.89^{+0.92}_{-0.74}\,\mathrm{Myr}$. The reconstructed orbit exhibits a clear perigalactic turning point and only a single crossing of the Galactic midplane ($P_{\rm cross} > 0.95$). These properties suggest that DESI-HVS1 is most naturally explained by the Hills mechanism, although alternative scenarios cannot be entirely ruled out. Its discovery provides the first strong evidence for an old, low-mass HVS candidate consistent with a GC origin, indicating that the apparent dominance of young, massive GC-origin HVSs is likely a consequence of observational selection effects. |
| title | An Old, Low-mass, Metal-poor Hypervelocity Star Candidate Consistent with a Galactic Center Origin |
| topic | Astrophysics of Galaxies Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2604.21646 |