Universität zu Köln

Mackey, Jonathan ORCID: 0000-0002-5449-6131, Haworth, Thomas J., Gvaramadze, Vasilii V., Mohamed, Shazrene ORCID: 0000-0002-1856-9225, Langer, Norbert and Harries, Tim J. (2016). Detecting stellar-wind bubbles through infrared arcs in H II regions. Astron. Astrophys., 586. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 1432-0746

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Abstract

Mid-infrared arcs of dust emission are often seen near ionizing stars within H II regions. A possible explanations for these arcs is that they could show the outer edges of asymmetric stellar wind bubbles. We use two-dimensional, radiation-hydrodynamics simulations of wind bubbles within H II regions around individual stars to predict the infrared emission properties of the dust within the H II region. We assume that dust and gas are dynamically well-coupled and that dust properties (composition, size distribution) are the same in the H II region as outside it, and that the wind bubble contains no dust. We post-process the simulations to make synthetic intensity maps at infrared wavebands using the torus code. We find that the outer edge of a wind bubble emits brightly at 24 mu m through starlight absorbed by dust grains and re-radiated thermally in the infrared. This produces a bright arc of emission for slowly moving stars that have asymmetric wind bubbles, even for cases where there is no bow shock or any corresponding feature in tracers of gas emission. The 24 mu m intensity decreases exponentially from the arc with increasing distance from the star because the dust temperature decreases with distance. The size distribution and composition of the dust grains has quantitative but not qualitative effects on our results. Despite the simplifications of our model, we find good qualitative agreement with observations of the H II region RCW120, and can provide physical explanations for any quantitative differences. Our model produces an infrared arc with the same shape and size as the arc around CD -38 degrees 11636 in RCW120, and with comparable brightness. This suggests that infrared arcs around O stars in H II regions may be revealing the extent of stellar wind bubbles, although we have not excluded other explanations.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Mackey, Jonathan UNSPECIFIED orcid.org/0000-0002-5449-6131 UNSPECIFIED Haworth, Thomas J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Gvaramadze, Vasilii V. UNSPECIFIED UNSPECIFIED UNSPECIFIED Mohamed, Shazrene UNSPECIFIED orcid.org/0000-0002-1856-9225 UNSPECIFIED Langer, Norbert UNSPECIFIED UNSPECIFIED UNSPECIFIED Harries, Tim J. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-286091
DOI:	10.1051/0004-6361/201527569
Journal or Publication Title:	Astron. Astrophys.
Volume:	586
Date:	2016
Publisher:	EDP SCIENCES S A
Place of Publication:	LES ULIS CEDEX A
ISSN:	1432-0746
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language X-RAY-EMISSION; TRIGGERED STAR-FORMATION; MASSIVE RUNAWAY STARS; MILKY-WAY PROJECT; BOW SHOCKS; RADIATION-PRESSURE; INTERSTELLAR BUBBLES; OB STARS; CIRCUMSTELLAR MEDIUM; PHYSICAL-PROPERTIES Multiple languages Astronomy & Astrophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/28609