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 ..
Instrument
CAM01 , CAM04 , SWS06
Temporal Coverage
1998-03-14T20:15:23Z/1998-03-15T00:11:07Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the world's first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
