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==> In this proposal, more time is being requested for DLIS.GCDRIDGE
==> This proposal requests an upgrade from Priority 3 for DLIS.GCDRIDGE
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An unbiased submillimeter continuum survey of the central region of the Milky
Way performed at the CSO revealed a number of unique compact GMC cores forming
an elongated ridge connected to the Galactic center radio arc. These massive
GMC cores appear distinctly different from previously studied galactic center
sources in terms of their continuum spectral energy distributions and
star-formation properties.  In particular, no compact FIR sources or HII
regions associated with these dust condensations are found in the existing
surveys.  The detection of MASSIVE and COLD GMC cores in the nuclear disk,
apparently WITHOUT ONGOING HIGH-MASS STAR FORMATION, would be of great
importance, allowing a new assessment of various effects that have been invoked
to explain the low rate of high-mass star formation in the central region.
We propose observations of the FIR continuum emission from the compact GMC
cores detected in the CSO survey ridge using ISO to address two important
outstanding questions. First, these observations will allow a sensitive search
for compact FIR sources that may be embedded in the cores and thus provide
definitive information on the current state of star formation in this region.
Second, they will yield estimates of the dust temperature and thus allow to
constrain grain properties and improve mass estimates. Existing
multi-wavelength submillimeter observations predict observable 100 micron
emission from extended portions of the ridge for all plausible values of the
dust temperature and grain emissivity. With the KAO de-commissioned, ISO is the
only instrument capable of performing these observations in the predictable
future.