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T. B. O'Hara, M. Meixner, A. K. Speck, T. Ueta (Univ. of Illinois, Urbana-Champaign), M. Bobrowsky (Challenger Center)
We present infrared observations and model calculations of the dust shell surrounding HD 168625 (IRAS 18184-1623). This object is a candidate Luminous Blue Variable due to its photometric variations and the presence of a detached dust shell indicating a major mass-loss episode several hundred years ago. We have conducted a multi-wavelength infrared study of HD 168625, and present here high-resolution near-infrared imaging from NICMOS on HST, which shows substructure in a shell that is clearly detached from the star. We also present temperature and optical depth maps derived from mid-infrared images, which illustrate the toroidal geometry of the dust shell.
In addition the these observations, we have modelled the dust shell of HD 168625 using the radiative transfer code 2-Dust, using observationally determined stellar parameters and geometric dust shell parameters as a starting point. We present here a comparison of the model spectral energy distribution to infrared photometry data, and compare model and data images of the dust shell. The shell can be modelled by a dust distribution that is largely disk-like (equator-to-pole density ratio ~30) but with an elliptical midshell, as would be formed from the interaction of a fast wind with a pre-existing density constrast.
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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.