Contents of: VI/111/./abstract/TTSUJI_REDSTAR1.abs

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SCIENTIFIC ABSTRACT
   Mass-loss from intermediate mass stars is the major ingredient in our
understanding  not only of stellar evolution but also of the Galactic chemical 
evolution as a whole. It is known that the large mass-loss takes place at the
latest stage of stellar evolution represented by red (super)giants and AGB 
stars, but the origin of the mass-loss in these stages is poorly understood. 
For clarifying the origin of mass-loss, the first step should be to understand
the physical structure of the upper atmosphere-inner circumstellar envelope
(or outer atmosphere) where mass-loss outflow originates in these stars. This 
outer atmosphere can best be probed directly by the rich spectra due to atoms
(including f-f continuum), gaseous molecules (vib-rot and pure rot) and dusts
in the thermal infrared region to be observed by the ISO SWS. 
   The infrared radiation in the thermal infrared region between 2.4 and 45
micron includes the contributions from the upper photosphere, stellar
chromosphere, and inner circumstellar envelopes. To better interpret these
complicated spectra, we think it useful to do systematic survey of infrared
spectra of cool evolved stars with different characteristics, and we propose
to observe red supergiants including bright OH/IR sources in LMC, red giants 
and Mira variables, carbon stars of different characteristics (N-,J-,CS-,CH-
types), and some peculiar carbon stars including transition objects to PNe.

OBSERVATION SUMMARY
   We use the low resolution mode of SWS (SWS01-1) to see the global structure
of the infrared radiation. This mode is ideal to map the thermal structure of
the gas/dust envelopes. We apply this mode to observe some 30 objects that may
sample the major objects in the temperature - luminosity - O/C ratio -
metallicity - peculiarity space of cool evolved stars. For 10 representative 
objects in the parameter space, we use the normal grating mode of SWS (SWS06)
to observe the full SWS range with the expected resolution of about 2,000,
which will be necessary to resolve the molecular bands. The results of these
observations will provide the basic data to model the physical structure of the
photosphere and outer atmospheres of cool evolved stars.
   We also apply the normal grating mode (SWS06) to the restricted spectral
region for some additional objects, and we further try the high resolution 
observation by the FP mode (SWS07).  Here, we explore some possibilities to 
observe the molecular lines of the circumstellar origin.  For carbon-rich 
objects, the major interests are the HCN nu2 (14.0 micron) and C2H2 nu5 (13.7
micron) bands whose strong Q-branch complex can be identified by the medium 
resolution of the grating scan (SWS06). For oxygen-rich stars, OH pure rotation
lines are the major possibility, but high resolution of the FP mode is needed
to resolve these lines. We focus our attention to the quartets at 14.6micron
and 16.8 micron (SWS07). We can expect to observe the photospheric
component if thermal emission is not strong, but otherwise we expect to observe
those originating in the circumstellar envelopes, either as emission or as
absorption against the continuum due to the dust thermal emission. We also hope
to measure radial velocity and to clarify the kinematics of inner circumstellar
envelopes, which may be difficult to probe by the millimeter spectroscopy. This
observation is restricted to a few very bright objects.  

© UDS/CNRS

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