Program: GS-2009A-Q-6

Last year Smith et al. (2007) reported the discovery of a new equatorial ring nebula, called SBW1, around a blue supergiant seen in the Carina Nebula. It has morphology and physical dimensions almost identical to the ring around SN1987A and it surrounds an early B supergiant that is a virtual twin ofthe progenitor of SN1987A. However, it is more than 20 times closer than SN1987A, and therefore shows the detailed structure of this unusual type of ring nebula in much greater detail, before the star explodes. Resolving the structure in this nebula will inform our understanding of non-spherical mass loss from supernova progenitor stars in general, and will constrain models of SN1987A as its blast wave continues to interact with its circumstellar ring. This proposal aims to obtain mid-IR images and spectroscopy of SBW1 with T-ReCS on Gemini South in order to determine the dust properties in the nebula, such as its physical location, temperature, mass, and composition, for comparison with the dust properties of SN1987A's ring and also with the circumstellar dust properties of other blue supergiants like B[e] stars. These IR data are also needed to understand the relationship between warm dust and the ionized gas structures that will be resolved in our accepted program to obtain WFC3 and STIS data with HST.