Ionized gas kinematics in bipolar H ii regions

Abstract

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 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, G316.81–0.06, which lies at the centre of a massive (∼103 M⊙) infrared dark cloud filament. It is still accreting molecular gas as well as driving a ∼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 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 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) H II regions. We suggest that further quantitative analysis of the ionized gas kinematics of young H II regions, combined with additional simulations, should improve our understanding of feedback at these early stages.

More information

Identifiers

ORCID for Hannah S. Dalgleish: orcid.org/0000-0002-8970-3065

Catalogue record

Export record

Altmetrics