Filamentary condensations in a young cluster
  New models are presented for star-forming condensations in clusters. In each
model, the condensation mass increases linearly with radius on small scales,
and more rapidly on large scales, as in "thermal-nonthermal" models. Spherical
condensations with this structure form protostars which match the IMF if their
infall is subject to equally likely stopping. However such spherical models do
not match the filamentary nature of cluster gas, and they are too extended to
form protostars having high mass and short spacing. Two hybrid models are
presented, which are spherical on small scales and filamentary on large scales.
In and around clusters, cores embedded in linear filaments match the elongation
of cluster gas, and the central concentration of low-mass stars. In cluster
centers, condensations require a low volume filling factor to produce massive
stars with short spacing. These may have stellate shape, where cores are nodes
of filamentary networks, as seen in some simulations of colliding flows and of
collapsing turbulent clumps. A dense configuration of such stellate
condensations may be indistinguishable from a clump forming multiple protostars
via filamentary flow paths.
