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arXiv · 1805.00479

Ionised gas kinematics in bipolar H II regions

Hannah S. Dalgleish·Steven N. Longmore·Thomas Peters·Jonathan D. Henshaw·Joshua L. Veitch-Michaelis·James S. Urquhart
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Abstract

Stellar feedback plays a fundamental role in shaping the evolution of galaxies. Here we explore the use of ionised gas kinematics in young, bipolar H II regions as a probe of early feedback in these star-forming environments. We have undertaken a multiwavelength study of a young, bipolar H II region in the Galactic disc, G$316.81-0.06$, which lies at the centre of a massive ($\sim10^3$ M$_{\odot}$) infrared-dark cloud filament. It is still accreting molecular gas as well as driving a $\sim 0.2$ pc ionised gas outflow perpendicular to the filament. Intriguingly, we observe a large velocity gradient ($47.81 \pm 3.21$ km s$^{-1}$ pc$^{-1}$) across the ionised gas in a direction perpendicular to the outflow. This kinematic signature of the ionised gas shows a reasonable correspondence with the simulations of young H II regions. Based on a qualitative comparison between our observations and these simulations, we put forward a possible explanation for the velocity gradients observed in G$316.81-0.06$. If the velocity gradient perpendicular to the outflow is caused by rotation of the ionised gas, then we infer that this rotation is a direct result of the initial net angular momentum in the natal molecular cloud. If this explanation is correct, this kinematic signature should be common in other young (bipolar) H II regions. We suggest that further quantitative analysis of the ionised gas kinematics of young H II regions, combined with additional simulations, should improve our understanding of feedback at these early stages.

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Hannah S. Dalgleish, Steven N. Longmore, Thomas Peters, Jonathan D. Henshaw, Joshua L. Veitch-Michaelis, James S. Urquhart. 2018-05-01. Ionised gas kinematics in bipolar H II regions. https://doi.org/10.1093/mnras%2Fsty1109

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