NGC 7538 IRS2 in NeII : Shell and Cavity Kinematics of a Compact HII Region by Dan Beilis et al. on Wednesday 30 November

NGC 7538 IRS2 is a compact HII region and recent star formation source, with

a shell morphology, lying on the border of the visible HII region NGC 7538. We

present a spectral cube of the [NeII] 12.8 micron emission line obtained with

the TEXES spectrometer on Gemini North with velocity resolution approximately 4

km/s and angular resolution 0.3". The kinematics of the data cube show ionized

gas flowing along multiple cavity walls. We have simulated the kinematics and

structure of IRS2 with a model of superimposed cavities created by outflows

from embedded stars in a cloud with density gradients. Most of the cavities,

including the largest that dominates IRS2 structure, are associated with B-type

stars; the outflow of the bright ionizing O star binary IRS2a/b is small in

extent and lies in a high-density clump. The IRS2 model shows that the behavior

of an HII region is not a matter of only the most massive star present; cloud

clumpiness and activity of lower mass stars may determine the structure and

kinematics.

arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.16861v1