The following document lists the file abstract/NTRAMS_LMCSPECT.abs
from catalogue VI/111.
A plain copy of the file
(without headers/trailers) may be downloaded.
This proposal is intended as a follow up to the Guaranteed time proposal by N. Trams et al (NTRAMS, LMCAGB1 and LMCAGB2). In that proposal photometry was obtained of a group of AGB stars in the LMC. The observations were limited to 12, 25 and 60 microns, and for some object PHOT-S spectra were obtained. Unfortunately the quality of the spectra, as well as the quality of the 60 micron photometry was insufficient. The spectra are important to be able to see the effect of different chemistry on the infrared colours of AGB stars in the Magellanic Clouds. In our own galaxy it is known that oxygen rich and carbon rich AGB stars have different IR colours (the O-rich stars being brighter at 12 micron due to the silicate feature). We therefore propose to obtain spectra for a subsample of the objects observed in the guaranteed time with higher S/N using the ISOCAM instrument. We have also included 10 SMC AGB stars from the GT programme of J. Blommaert (JBLOMMAE, SMC_AGB) in the target list. The 60 micron photometry is especially important for the mass loss rate, since at this wavelength we observe the Rayleigh-Jeans end of the dust energy distribution. The ISOPHOT observations done in the guaranteed time were severely hampered by the reduction of the sensitivity of the instrument. In this proposal we therefore propose to observe a subsample of the stars observed in the guaranteed time, using ISOPHOT in raster mapping mode, in order to get a much better background and flatfield determination, to increase the detection rate of these (faint objects).