= > in this proposal, more time is being requested for skwok.ex_cstar = carbon stars have traditionally been identified by either optical spectroscopy or by infrared spectroscopy through the detection of the 11.3 micron sic emission feature. the latter group, which are called infrared carbon stars or sic carbon stars are undergoing significant mass loss and are likely to represent a more evolved stage of evolution than the former group. more recently, we have identified another group of carbon stars which we call extreme carbon stars. these are stars that have thick circumstellar envelopes with a featureless dust continuum in the 10-20 micron region. the derived mass loss rates of these extreme carbon stars are so high that they must be near the end of their asymptotic giant branch of evolution. however, the nature and composition of the dust grains in these extreme carbon stars are not certain. iso observations, with better spectral coverage and higher spectral resolutions than previously possible from ground-based observations, will yield important data to answer this question. we request sws and lws observations of two extreme carbon stars which are observable in the remaining lifetime of iso. one is a very bright object for which high quality spectra will be easily obtained. the other object appears to have a dust shell of higher optical depth than for any other extreme carbon star and it may also have a distinct dust composition (volk, kwok and langill 1992; apj, 391, 285). radiative transfer modeling of the observed spectra can then be carried out to derive the dust opacity properties and mass loss history of these objects.
Instrument
SWS01
Temporal Coverage
1997-10-26T05:08:30Z/1997-10-26T05:40:22Z
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.
