Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Modeling the submillimeter emission from the Cepheus A young stellar
  cluster: Evidence for large scale collapse   Evidence for a large scale flow of low density gas onto the Cepheus A young
stellar cluster is presented. Observations of K-band near-infrared and
multi-transition CS and N2H+ millimeter line emission are shown in relation to
a sub-millimeter map of the cool dust around the most embedded stars. The
near-infrared emission is offset from the dust peak suggesting a shift in the
location of star formation over the history of the core. The CS emission is
concentrated toward the core center but N2H+ peaks in two main cores offset
from the center, opposite to the chemistry observed in low mass cores. A
starless core with strong CS but weak N2H+ emission is found toward the western
edge of the region. The average CS(2-1) spectrum over the cluster forming core
is asymmetrically self-absorbed suggesting infall. We analyze the large scale
dynamics by applying a one-dimensional radiative transfer code to a model
spherical core with constant temperature and linewidth, and a density profile
measured from an archival 850 micron map of the region. The best fit model that
matches the three CS profiles requires a low CS abundance in the core and an
outer, infalling envelope with a low density and undepleted CS abundance. The
integrated intensities of the two N2H+ lines is well matched with a constant
N2H+ abundance. The envelope infall velocity is tightly constrained by the
CS(2-1) asymmetry and is sub-sonic but the size of the infalling region is
poorly determined. The picture of a high density center with depleted CS slowly
accreting a low density outer envelope with normal CS abundance suggests that
core growth occurs at least partially by the dissipation of turbulent support
on large scales.

31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
7
The categories of this paper are: hep-th
29
The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
19
The categories of this paper are: eess
23
The categories of this paper are: solv-int
0
The categories of this paper are: hep-ph
30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
14
The categories of this paper are: math-ph
2
The categories of this paper are: math