Core to ultracompact HII region evolution in the W49A massive protocluster
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arXiv
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| Autori principali: | , , , , , , , , , , , , |
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| Natura: | Preprint |
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2024
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| author | Nony, T. Galván-Madrid, R. Brouillet, N. Suárez, G. Louvet, F. De Pree, C. G. Juárez-Gama, M. Ginsburg, A. Immer, K. Lin, Y. Liu, H. B. Román-Zúñiga, C. G. Zhang, Q. |
| author_facet | Nony, T. Galván-Madrid, R. Brouillet, N. Suárez, G. Louvet, F. De Pree, C. G. Juárez-Gama, M. Ginsburg, A. Immer, K. Lin, Y. Liu, H. B. Román-Zúñiga, C. G. Zhang, Q. |
| contents | We aim to identify and characterize cores in the high-mass proto-cluster W49, determine their evolutionary stages and measure the associated lifetimes. We built a catalog of 129 cores extracted from an ALMA 1.3 mm continuum image at 0.26" (2900 au) angular resolution. The association between cores and Hyper/Ultra Compact HII (H/UC HII) regions was established from the analysis of VLA 3.3 cm continuum and H30$α$ line observations. We also looked for emission of hot molecular cores (HMCs) using the methyl formate doublet at 218.29 GHz. We identified 40 cores associated with an H/UC HII region and 19 HMCs over the ALMA mosaic. The 52 cores with an H/UC HII region and/or a HMC are assumed to be high-mass protostellar cores, while the rest of the core population likely consists in prestellar cores and low-mass protostellar cores. We found a good agreement between the two tracers of ionized gas, with 23 common detections and only four cores detected at 3.3 cm and not in H30$α$. The spectral indexes from 3.3 cm to 1.3 mm range from 1, for the youngest cores with partially optically thick free-free emission, to about -0.1, that is optically thin free-free emission obtained for cores likely more evolved. Using as a reference the H/UC HII regions, we found the statistical lifetimes of the HMC and massive protostellar phases in W49N to be about $6\times10^4$ yr and $1.4\times10^5$ yr, respectively. We also showed that HMC can co-exist with H/UC HII regions during a short fraction of the core lifetime, about $2\times10^4$ yr. This indicates a rapid dispersal of the inner molecule envelope once the HC HII is formed. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2404_02250 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Core to ultracompact HII region evolution in the W49A massive protocluster Nony, T. Galván-Madrid, R. Brouillet, N. Suárez, G. Louvet, F. De Pree, C. G. Juárez-Gama, M. Ginsburg, A. Immer, K. Lin, Y. Liu, H. B. Román-Zúñiga, C. G. Zhang, Q. Astrophysics of Galaxies Solar and Stellar Astrophysics We aim to identify and characterize cores in the high-mass proto-cluster W49, determine their evolutionary stages and measure the associated lifetimes. We built a catalog of 129 cores extracted from an ALMA 1.3 mm continuum image at 0.26" (2900 au) angular resolution. The association between cores and Hyper/Ultra Compact HII (H/UC HII) regions was established from the analysis of VLA 3.3 cm continuum and H30$α$ line observations. We also looked for emission of hot molecular cores (HMCs) using the methyl formate doublet at 218.29 GHz. We identified 40 cores associated with an H/UC HII region and 19 HMCs over the ALMA mosaic. The 52 cores with an H/UC HII region and/or a HMC are assumed to be high-mass protostellar cores, while the rest of the core population likely consists in prestellar cores and low-mass protostellar cores. We found a good agreement between the two tracers of ionized gas, with 23 common detections and only four cores detected at 3.3 cm and not in H30$α$. The spectral indexes from 3.3 cm to 1.3 mm range from 1, for the youngest cores with partially optically thick free-free emission, to about -0.1, that is optically thin free-free emission obtained for cores likely more evolved. Using as a reference the H/UC HII regions, we found the statistical lifetimes of the HMC and massive protostellar phases in W49N to be about $6\times10^4$ yr and $1.4\times10^5$ yr, respectively. We also showed that HMC can co-exist with H/UC HII regions during a short fraction of the core lifetime, about $2\times10^4$ yr. This indicates a rapid dispersal of the inner molecule envelope once the HC HII is formed. |
| title | Core to ultracompact HII region evolution in the W49A massive protocluster |
| topic | Astrophysics of Galaxies Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2404.02250 |