An Ammonia Spectral Map of the L1495-B218 Filaments in the Taurus
  Molecular Cloud : I. Physical Properties of Filaments and Dense cores
  We present deep NH$_3$ observations of the L1495-B218 filaments in the Taurus
molecular cloud covering over a 3 degree angular range using the K-band focal
plane array on the 100m Green Bank Telescope. The L1495-B218 filaments form an
interconnected, nearby, large complex extending over 8 pc. We observed NH$_3$
(1,1) and (2,2) with a spectral resolution of 0.038 km/s and a spatial
resolution of 31$"$. Most of the ammonia peaks coincide with intensity peaks in
dust continuum maps at 350 $\mu$m and 500 $\mu$m. We deduced physical
properties by fitting a model to the observed spectra. We find gas kinetic
temperatures of 8 $-$ 15 K, velocity dispersions of 0.05 $-$ 0.25 km/s, and
NH$_3$ column densities of 5$\times$10$^{12}$ $-$ 1$\times$10$^{14}$ cm$^{-2}$.
The CSAR algorithm, which is a hybrid of seeded-watershed and binary dendrogram
algorithms, identifies a total of 55 NH$_3$ structures including 39 leaves and
16 branches. The masses of the NH$_3$ sources range from 0.05 M$_\odot$ to 9.5
M$_\odot$. The masses of NH$_3$ leaves are mostly smaller than their
corresponding virial mass estimated from their internal and gravitational
energies, which suggests these leaves are gravitationally unbound structures. 9
out of 39 NH$_3$ leaves are gravitationally bound and 7 out of 9
gravitationally bound NH$_3$ leaves are associated with star formation. We also
found that 12 out of 30 gravitationally unbound leaves are pressure-confined.
Our data suggest that a dense core may form as a pressure-confined structure,
evolve to a gravitationally bound core, and undergo collapse to form a
protostar.
