Misc,
On the nature of supersonic turbulence in Giant HII Regions
(2019)cite arxiv:1912.03543Comment: 9 pages, 11 figures, submitted for publication in A&A.
Abstract
New FLAMES/GIRAFFE public data allows to revisit the issue of the origin of
the supersonic turbulence inferred in the ionized gas of Giant HII Regions
using the prototypical 30~Doradus nebula in the LMC as a guide. We find that
the velocity width of the integrated H$\alpha$ line-profile of 30~Doradus can
only be explained by the motion of macroscopic parcels of gas driven by the
gravitational potential of the stars and gas with a significant contribution of
stellar winds. At all positions within the nebula we find that an additional
very broad ($\sigma=40-50$~\kms) unresolved component is required to fit the
extended wings of the profiles. We find that fitting two Gaussian components to
the integrated emission-line profiles provides a robust way of separating the
contributions of stellar winds and gravity. Assuming an effective radius of
10pc for the nebula we thus infer a dynamical mass of $\sim10^6$~\msun~ for
30Dor. Our analysis of published observations of the second largest Giant HII
Region in the Local Group, NGC~604, shows that our results for 30~Doradus apply
to GHR as a class.
