HE0144-4657: A Carbon-Enhanced Ultra Metal-Poor Star ([Fe/H] ~ -4.1) from the Helmi Stream Disrupted Dwarf Galaxy
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| Format: | Preprint |
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2026
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| _version_ | 1866915894388588544 |
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| author | Placco, Vinicius M. Limberg, Guilherme Kennedy, Catherine R. Christlieb, Norbert |
| author_facet | Placco, Vinicius M. Limberg, Guilherme Kennedy, Catherine R. Christlieb, Norbert |
| contents | We present the discovery of HE0144-4657, an ultra metal-poor, CNO-enhanced star dynamically associated with the Helmi Stream disrupted dwarf-galaxy remnant. This star was first identified as a carbon-enhanced, metal-poor star candidate from the Hamburg/ESO objective-prism survey, then followed up with medium- and high-resolution spectroscopy. At [Fe/H]=-4.11, HE0144-4657 is the lowest metallicity star found in a stellar stream to date. Its chemistry is consistent with field halo stars in the same metallicity regime, and the light-element (atomic number Z<=30) chemical abundance pattern suggests that HE0144-4657 is a bona-fide second-generation star with a possible Population III progenitor in the 50Msun mass range with low explosion energy. One possible scenario for the origin of HE0144-4657 is that it was formed in an ultra-faint dwarf galaxy accreted by the Helmi Stream progenitor system before merging with the Milky Way. This discovery provides further evidence for the extragalactic origin of carbon-enhanced ultra metal-poor stars in the Milky Way and for the specific environments conducive to their formation. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2601_15974 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | HE0144-4657: A Carbon-Enhanced Ultra Metal-Poor Star ([Fe/H] ~ -4.1) from the Helmi Stream Disrupted Dwarf Galaxy Placco, Vinicius M. Limberg, Guilherme Kennedy, Catherine R. Christlieb, Norbert Astrophysics of Galaxies Solar and Stellar Astrophysics We present the discovery of HE0144-4657, an ultra metal-poor, CNO-enhanced star dynamically associated with the Helmi Stream disrupted dwarf-galaxy remnant. This star was first identified as a carbon-enhanced, metal-poor star candidate from the Hamburg/ESO objective-prism survey, then followed up with medium- and high-resolution spectroscopy. At [Fe/H]=-4.11, HE0144-4657 is the lowest metallicity star found in a stellar stream to date. Its chemistry is consistent with field halo stars in the same metallicity regime, and the light-element (atomic number Z<=30) chemical abundance pattern suggests that HE0144-4657 is a bona-fide second-generation star with a possible Population III progenitor in the 50Msun mass range with low explosion energy. One possible scenario for the origin of HE0144-4657 is that it was formed in an ultra-faint dwarf galaxy accreted by the Helmi Stream progenitor system before merging with the Milky Way. This discovery provides further evidence for the extragalactic origin of carbon-enhanced ultra metal-poor stars in the Milky Way and for the specific environments conducive to their formation. |
| title | HE0144-4657: A Carbon-Enhanced Ultra Metal-Poor Star ([Fe/H] ~ -4.1) from the Helmi Stream Disrupted Dwarf Galaxy |
| topic | Astrophysics of Galaxies Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2601.15974 |