Ionized gas kinematics in bipolar HII regions

作者：Dalgleish Hannah S^*; Longmore Steven N; Peters Thomas; Henshaw Jonathan D; Veitch Michaelis Joshua L; Urquhart James S

来源：Monthly Notices of the Royal Astronomical Society, 2018, 478(3): 3530-3543.

DOI：10.1093/mnras/sty1109

• stars: kinematics and dynamics
• stars: massive
• stars: protostars
• H II regions

Stellar feedback plays a fundamental role in shaping the evolution of galaxies. Here, we explore the use of the ionized gas kinematics in young, bipolar HII regions as a probe of early feedback in these star-forming environments. We have undertaken a multiwavelength study of a young, bipolar HII region in the Galactic disc, G316.81-0.06, which lies at the centre of a massive (similar to 10(3) M-circle dot) infrared dark cloud filament. It is still accreting molecular gas as well as driving a similar to 0.2 pc ionized gas outflow perpendicular to the filament. Intriguingly, we observe a large velocity gradient (47.81 +/- 3.21 km s(-1) pc(-1)) across the ionized gas in a direction perpendicular to the outflow. This kinematic signature of the ionized gas shows a reasonable correspondence with the simulations of young HII regions. Based on a qualitative comparison between our observations and these simulations, we put forward a possible explanation for the velocity gradients observed in G316.81-0.06. If the velocity gradient perpendicular to the outflow is caused by the rotation of the ionized 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) HII regions. We suggest that further quantitative analysis of the ionized gas kinematics of young HII regions, combined with additional simulations, should improve our understanding of feedback at these early stages.

• 出版日期2018-8