| Autor: |
Zhang, C., Zhu, Feng-Yao, Liu, Tie, Ren, Z. -Y., Liu, H. -L., Wang, Ke, Wu, J. -W., Zhang, Y., Zhou, J. -W., Tatematsu, K., Garay, Guido, Tej, Anandmayee, Li, Shanghuo, Xu, W. F., Lee, Chang Won, Bronfman, Leonardo, Soam, Archana, Li, D. |
| Rok vydání: |
2023 |
| Předmět: |
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| Druh dokumentu: |
Working Paper |
| DOI: |
10.1093/mnras/stad190 |
| Popis: |
Hydrogen recombination lines (RRLs) are one of the major diagnostics of the physical properties of H{\sc ii} regions. We use RRL H40$\alpha$, He40$\alpha$ and 3 mm continuum emission to investigate the properties of a large sample of resolved UC H{\sc ii} regions identified in the ATOMS survey. In total, we identify 94 UC H{\sc ii} regions from H40$\alpha$ emission. The basic parameters for these UC H{\sc ii} regions such as electron density, emission measure, electron temperature, ionic abundance ratio (n$_{\rm He^+}$/n$_{\rm H^+}$), and line width are derived. The median electron density and the median n$_{\rm He^+}$/n$_{\rm H^+}$ ratio of these UC H{\sc ii} regions derived from RRLs are $\sim$9000 cm$^{-3}$ and 0.11, respectively. Within UC H{\sc ii} regions, the n$_{\rm He^+}$/n$_{\rm H^+}$ ratios derived from the intensity ratio of the He40$\alpha$ and H40$\alpha$ lines seems to be higher in the boundary region than in the center. The H40$\alpha$ line width is mainly broadened by thermal motion and microturbulence. The electron temperature of these UC H{\sc ii} regions has a median value of $\sim$6700 K, and its dependence on galactocentric distance is weak. |
| Databáze: |
arXiv |
| Externí odkaz: |
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