We propose an observation of the high-velocity outflow of evolved
objects with mid- and far-infrared atomic / ionic lines by SWS and LWS.
   The high-velocity outflows in the circumstellar envelope of evolved
stars have been discovered mostly by radio molecular line observations.
The velocity of the wind often exceeds 100km/s. Many of the objects
are so called "proto-planetary nebulae" which lie between the AGB and
planetary nebula phase. The mechanism of acceleration of the
high-velocity wind has still not been understood.
   The purpose of the present observation is to clarify the physical
conditions of the high-velocity flow and contiguous region in the
envelope. The region is thought to be near the central star and the gas
temperature is high. Atomic and ionic lines in mid- and far-infrared
are good tracers of such warm gas. In addition, shocks between the
high-velocity wind and the surrounding slowly expanding envelope play
an important role to determine the physical conditions in the region,
such as excitation or destruction of the molecules. These lines will
provide us important information about this phenomenon. Our goal is to
construct an unique model of the circumstellar envelope including the
high-velocity outflow.
   Two spectrometers, SWS and LWS with Fabry-Perot are used in the
observations. A total observation time of 23422sec is requested for
the autumn launch and 24089sec for the spring launch.