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| Autori principali: | , , , , , , , , , , , |
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| Natura: | Preprint |
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2025
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| Accesso online: | https://arxiv.org/abs/2510.16343 |
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| _version_ | 1866912657448108032 |
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| author | Gong, Yan Zhang, Zhi-yu Henkel, Christian Chen, C. -H. Rosie Yang, Wenjin Tang, Xindi Hunt, Leslie K. Weiss, Axel Wu, Gang Yan, Yaoting Grishunin, Konstantin Menten, Karl M. |
| author_facet | Gong, Yan Zhang, Zhi-yu Henkel, Christian Chen, C. -H. Rosie Yang, Wenjin Tang, Xindi Hunt, Leslie K. Weiss, Axel Wu, Gang Yan, Yaoting Grishunin, Konstantin Menten, Karl M. |
| contents | Oxygen isotope abundances and their ratios are fingerprints of stellar evolution and therefore provide a powerful tool in tracing the enrichment history of galaxies. However, their behavior in low-metallicity dwarf galaxies remains largely unexplored. The Small Magellanic Cloud (SMC), a nearby analog of young high-redshift galaxies, offers an ideal laboratory to investigate this regime. Using the Atacama Compact Array, we observed the $J=2\to 1$ transitions of $^{12}$CO, $^{13}$CO, C$^{18}$O, and C$^{17}$O from the massive star-forming region LIRS~36 (aka N12A), achieving the first detection of C$^{17}$O in the SMC. This detection enables the first direct measurement of the $^{18}$O/$^{17}$O abundance ratio of 0.87$\pm$0.26 in this galaxy, substantially lower than all values in the literature, including molecular clouds in the Milky Way and other galaxies. Such a low ratio of $^{18}$O/$^{17}$O, together with a high $^{13}$CO/C$^{18}$O ratio, indicates chemical enrichment dominated by low-mass stars, consistent with the observed paucity of high-mass stars in the SMC. We suggest that the SMC is governed by a top-light integrated galaxy-wide initial mass function, predicted by the SMC's persistently low star-formation activities. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2510_16343 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Oxygen isotopes reveal low-mass star dominance in the Small Magellanic Cloud Gong, Yan Zhang, Zhi-yu Henkel, Christian Chen, C. -H. Rosie Yang, Wenjin Tang, Xindi Hunt, Leslie K. Weiss, Axel Wu, Gang Yan, Yaoting Grishunin, Konstantin Menten, Karl M. Astrophysics of Galaxies Oxygen isotope abundances and their ratios are fingerprints of stellar evolution and therefore provide a powerful tool in tracing the enrichment history of galaxies. However, their behavior in low-metallicity dwarf galaxies remains largely unexplored. The Small Magellanic Cloud (SMC), a nearby analog of young high-redshift galaxies, offers an ideal laboratory to investigate this regime. Using the Atacama Compact Array, we observed the $J=2\to 1$ transitions of $^{12}$CO, $^{13}$CO, C$^{18}$O, and C$^{17}$O from the massive star-forming region LIRS~36 (aka N12A), achieving the first detection of C$^{17}$O in the SMC. This detection enables the first direct measurement of the $^{18}$O/$^{17}$O abundance ratio of 0.87$\pm$0.26 in this galaxy, substantially lower than all values in the literature, including molecular clouds in the Milky Way and other galaxies. Such a low ratio of $^{18}$O/$^{17}$O, together with a high $^{13}$CO/C$^{18}$O ratio, indicates chemical enrichment dominated by low-mass stars, consistent with the observed paucity of high-mass stars in the SMC. We suggest that the SMC is governed by a top-light integrated galaxy-wide initial mass function, predicted by the SMC's persistently low star-formation activities. |
| title | Oxygen isotopes reveal low-mass star dominance in the Small Magellanic Cloud |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2510.16343 |