Contents of: VI/111/./abstract/HIZUMIUR_REDSTAR2.abs

The following document lists the file abstract/HIZUMIUR_REDSTAR2.abs from catalogue VI/111.
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SCIENTIFIC ABSTRACT
   We propose to obtain deep images of dust shells around bright AGB stars in
the solar neighbourhood at far-infrared wavelengths with ISOPHOT in order to
investigate mass-loss history in the AGB evolution by determining geometrical
structure of the circumstellar dust shells.
   With the results we will be able to examine the mass-loss history on time
scales from a few thousand to a hundred thousand years.  They will open a new
way for investigating non-steady mass-loss which is now drawing increasing
attention.  Modulation in the rates of mass-loss, which may be caused by
thermal pulses, will be observed if they are really present.  The issues posed
by IRAS will be elucidated by ISO.

OBSERVATION SUMMARY
   For most sources rectangular maps of 6.5'x30' and of 7.5'x30' will be
obtained with C_90 and C_160 filters, respectively, using the AOT PHT32.
One or two of the most extended sources will be observed with the wider
spatial coverage of 6.5'x45' and 7.5'x45' in order to obtain their full
brightness profiles.  In addition, an area of 30'x30' will be mapped with
the staring raster mode with C_160.
   The positions of map center for the observation numbers 7-10 and 23-26
in the autumn launch target list and 5-8 and 24-27 in the spring launch list
are for the case that the space craft y-axis is aligned to the direction of
either Right Ascension or Declination.  Since the direction of raster scans
will be chosen parallel to the space craft Y-axis in our observations,
those positions will be rotated on the sky about the positions of the central
stars according to the orientation of the space craft, and unpredictable now.
   The observation times given in the target lists are calculated using the
observer's manual for ISOPHOT.  Observation modes for each AGB object are
briefly summarized in the following tables.  We choose integration time per
each raster point of 16sec for all the observations having consulted an ESA
astronomer.  This is appropriate since our observations are concentrated on
regions having rather low and smooth brightness distribution.


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