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==> This proposal requests an upgrade from Priority 3 for some of the
==>   observations in MHAAS.EVOLSTAR
==> In addition, more time is being requested to complete and extend
==>   the work begun in the proposal MHAAS.EVOLSTAR
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The mass loss suffered by evolved stars controls their evolutionary fate and
provides a significant fraction of the total metal-enriched gas returned to the
ISM.  Stellar winds also represent a major birthing site for interstellar grains
-- both the wind acceleration mechanism and the dust formation process continue
to be of intense theoretical and observational interest.  We propose to study
these phenomena in nearby supergiants and other well-known, evolved stars by
observing the fine-structure lines of FeII(26,35um), SiII(35um), OI(63,146um),
and CII(158um).  These lines are believed to originate in the inner or trans-
ition regions of the circumstellar envelopes of evolved stars, in the very
region where molecules and dust are expected to form and the stellar winds are
presumably accelerated.  For the archetypal supergiant alpha Ori, we propose to
measure the brightest lines at high resolution (Fabry-Perot) to obtain dynamical
information about the outflowing gas.  This will help to establish the nature of
the emitting region and will also provide information on the gas-phase
abundances, temperature, and density of the gas, as well as the stellar mass-
loss rate and incident UV field.  The FeII(26), SiII(35), and OI(63) lines will
be observed in grating mode for an additional 18 evolved stars to determine
total masses of atomic gas, mass-loss rates, and the gas-phase abundances as a
function of spectral type, dust-to-gas ratio, and dust formation history.  Since
neither dust formation nor wind acceleration is well understood and effective
tracers of this warm, atomic gas are limited, these FIR observations are crucial
to our understanding of these enigmatic processes.