The following document lists the file abstract/RWATERS_R71CRYS.abs
from catalogue VI/111.
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We propose to study the IR spectrum of the Luminous Blue Variable (LBV) R71 in the LMC. This object, the brightest stellar source in the LMC at 25 microns, consists of a hot B supergiant with strong mass loss, and a detached asymmetric dust shell, which was ejected during a period of very high mass loss rate in the recent past. Using an SWS AOT01 speed 3 scan we have tentatively detected crystalline silicates in the detached dust envelope of R71. This is the first such detection in an extragalactic system, and in such a low metallicity environment; however, the S/N of the SWS AOT01 spectrum is not high. In addition, we have discovered 7.7 micron emission using PHOT-S, suggesting the presence of carbon-rich material. This may imply that the central star has already evolved to a C-rich chemistry. However, the S/N of the PHOT-S spectrum is insufficient to confirm the presence of other UIR bands at 3.3, 6.2 and 8.6 microns. With this proposal we request follow-up observations (CAM-CVF and SWS-AOT06), in order to (1) detect the other UIR bands, thus confirming the C-rich nature of part of the environment, and (2) to validate our tentative detection of extragalactic crystalline silicates. ==================================================================== ==> This proposal ... ====================================================================