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.
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