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==> In this proposal, more time is being requested for SVWB.1YSOSED
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Observations of the spectral energy distributions (SEDs) and
higher resolution spectra of circumstellar disks will be taken to
investigate the physical properties of the disks.  The principal
goals of the proposal are:
1. To determine if current theories of disk structure and heating
properly describe the spectral energy distributions between 5
and 200 microns.
2. To search for evolutionary changes in the disk properties
brought about by the formation of planetary systems,
gaps and holes in the disks, for example, and the dissipation
of the disks.
3. To resolve five outstanding questions about disk properties
which can only be assessed through high resolution observations:
a. how are the disks heated,
b. are the vertical temperature gradients in the disks positive
(heating from above) or negative (heating from within by
accretion),
c. what are the sizes of the disks,
d. what are the far infrared optical depths of the disks, and
e. are there gaps in the disk structure which can be identified
through the SEDs?
The current proposal is an extension of an ongoing ISO
investigation targetting the same questions.  The ongoing
investigation derives its source sample entirely from the
Chameleon dark cloud, the one available from the fall launch.
This proposal extends the investigation to the better studied
Taurus dark cloud.