Low-Metallicity Star Formation Survey in Sh2-284 (LZ-STAR). I. Ordered massive star formation in the outer Galaxy
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arXiv
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| Auteurs principaux: | , , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866908387587915776 |
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| author | Cheng, Yu Tan, Jonathan C. Andersen, Morten Fedriani, Rubén Zhang, Yichen Robberto, Massimo Li, Zhi-Yun Tanaka, Kei E. I. |
| author_facet | Cheng, Yu Tan, Jonathan C. Andersen, Morten Fedriani, Rubén Zhang, Yichen Robberto, Massimo Li, Zhi-Yun Tanaka, Kei E. I. |
| contents | Star formation is a fundamental, yet poorly understood, process of the Universe. It is important to study how star formation occurs in different galactic environments. Thus, here, in the first of a series of papers, we introduce the Low-Metallicity Star Formation (LZ-STAR) survey of the Sh2-284 (hereafter S284) region, which, at $Z\sim 0.3-0.5Z_\odot$, is one of the lowest-metallicity star-forming regions of our Galaxy. LZ-STAR is a multi-facility survey, including observations with {\it JWST}, {\it ALMA}, {\it HST}, {\it Chandra} and {\it Gemini}. As a starting point, we report {\it JWST} and {\it ALMA} observations of one of the most massive protostars in the region, S284p1. The observations of shock-excited molecular hydrogen reveal a symmetric, bipolar outflow originating from the protostar, spanning several parsecs, and fully covered by the {\it JWST} field of view and the {\it ALMA} observations of CO(2-1) emission. This allows us to infer that the protostar has maintained a relatively stable orientation of disk accretion over its formation history. The {\it JWST} near-IR continuum observations detect a centrally illuminated bipolar outflow cavity around the protostar, as well as a surrounding cluster of low-mass young stars. We develop new radiative transfer models of massive protostars designed for the low metallicity of S284. Fitting these models to the protostar's spectral energy distribution implies a current protostellar mass of $\sim10\:M_\odot$ has formed from an initially $\sim100\:M_\odot$ core over the last $\sim3\times10^5$ years. Overall, these results indicate that massive stars can form in an ordered manner in low-metallicity, protocluster environments. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2503_14460 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Low-Metallicity Star Formation Survey in Sh2-284 (LZ-STAR). I. Ordered massive star formation in the outer Galaxy Cheng, Yu Tan, Jonathan C. Andersen, Morten Fedriani, Rubén Zhang, Yichen Robberto, Massimo Li, Zhi-Yun Tanaka, Kei E. I. Astrophysics of Galaxies Star formation is a fundamental, yet poorly understood, process of the Universe. It is important to study how star formation occurs in different galactic environments. Thus, here, in the first of a series of papers, we introduce the Low-Metallicity Star Formation (LZ-STAR) survey of the Sh2-284 (hereafter S284) region, which, at $Z\sim 0.3-0.5Z_\odot$, is one of the lowest-metallicity star-forming regions of our Galaxy. LZ-STAR is a multi-facility survey, including observations with {\it JWST}, {\it ALMA}, {\it HST}, {\it Chandra} and {\it Gemini}. As a starting point, we report {\it JWST} and {\it ALMA} observations of one of the most massive protostars in the region, S284p1. The observations of shock-excited molecular hydrogen reveal a symmetric, bipolar outflow originating from the protostar, spanning several parsecs, and fully covered by the {\it JWST} field of view and the {\it ALMA} observations of CO(2-1) emission. This allows us to infer that the protostar has maintained a relatively stable orientation of disk accretion over its formation history. The {\it JWST} near-IR continuum observations detect a centrally illuminated bipolar outflow cavity around the protostar, as well as a surrounding cluster of low-mass young stars. We develop new radiative transfer models of massive protostars designed for the low metallicity of S284. Fitting these models to the protostar's spectral energy distribution implies a current protostellar mass of $\sim10\:M_\odot$ has formed from an initially $\sim100\:M_\odot$ core over the last $\sim3\times10^5$ years. Overall, these results indicate that massive stars can form in an ordered manner in low-metallicity, protocluster environments. |
| title | Low-Metallicity Star Formation Survey in Sh2-284 (LZ-STAR). I. Ordered massive star formation in the outer Galaxy |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2503.14460 |