The Photo-Dissociation Region Surrounding HR 5171AB
Abstract
HR 5171AB is an example of how an extremely massive star, a hypergiant, and its hot companion play the dominant role in their local environment. Their effects are demonstrated by first creating and then shaping what is likely a large Photo-Dissociation Region (PDR, Radius ∼8 pc) out of the molecular cloud in which they formed. We present extremely sensitive Spitzer Space Telescope IRAC images, as well as MSX and IRAS/IRIS data, that show this region in the mid-IR with previously unseen detail. The PDR surrounding HR 5171 lies at the outermost limits of the RCW 80 HII region, and is spatially well correlated with a molecular cloud at the same kinematic distance. The mid-IR colors of the dust and gas surrounding HR 5171 show a definite lack of shocked material. When combined with the expected colors for dust in a uniform UV radiation field, the data make a strong case for a quiescent PDR. The origins of the PDR likely date to when HR 5171A was a main sequence O-type star (∼50 Mo), and the current sustaining ionization source is its companion HR 5171B (B0 Ibp).
This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Support for this work was provided by NASA.- Publication:
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American Astronomical Society Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AAS...209.8420S