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A major problem in astrophysics is how stars form in clusters of ~100 or
more members, in a region extending over ~1 pc, in a time period of ~1 Myr,
and with a mass distribution following the initial mass function. One of
the fundamental questions in astrophysics is how do the initial conditions
for star formation differ from isolated cores to cluster forming regions.
Observations at high spectral and spatial resolution are needed, and only
interferometers operating at millimeter and submillimeter wavelengths are
able to provide the necessary data.
With the SMA and single-dish mm/submm telescopes, we have begun a program
to determine the internal structures of staress cores in nearby
cluster-forming regions, such as Ophiuchus and NGC 1333. We have focused
on observations of N2H+ and N2D+ as molecules which probe densities 3 x
105 cm-3, and suffer negligible depletion due to freeze-out onto dust
grains. These observations allow us to measure their degree of
deuteration, column density, volume density, size, line widths, and
velocity gradients, and to compare these properties to those of the more
isolated cores, which have been observed extensively in these lines.
Currently only 1-2 cores in each cluster-forming region to be studied at
this level of detail, due to limited sensitivity. This program is thus a
path-finder for observations with ALMA, which will enable tens of cores in
each region to be probe internally.
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