Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Modelling submillimetre spectra of the protostellar infall candidates
  NGC1333-IRAS2 and Serpens SMM4   We present a radiative transfer model, which is applicable to the study of
submillimetre spectral line observations of protostellar envelopes. The model
uses an exact, non-LTE, spherically symmetric radiative transfer `Stenholm'
method, which numerically solves the radiative transfer problem by the process
of `Lambda-iteration'. We also present submillimetre spectral line data of the
Class 0 protostars NGC1333-IRAS2 and Serpens SMM4. We examine the physical
constraints which can be used to limit the number and range of parameters used
in protostellar envelope models, and identify the turbulent velocity and tracer
molecule abundance as the principle sources of uncertainty in the radiative
transfer modelling. We explore the trends in the appearance of the predicted
line profiles as key parameters in the models are varied.
  We find that the separation of the two peaks of a typical infall profile is
dependent not on the evolutionary status of the collapsing protostar, but on
the turbulent velocity dispersion in the envelope. We also find that the line
shapes can be significantly altered by rotation.
  Fits are found for the observed line profiles of IRAS2 and SMM4 using
plausible infall model parameters. The density and velocity profiles in our
best fit models are inconsistent with a singular isothermal sphere model. We
find better agreement with a form of collapse which assumes non-static initial
conditions. We also find some evidence that the infall velocities are retarded
from free-fall towards the centre of the cloud, probably by rotation, and that
the envelope of SMM4 is rotationally flattened.

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The categories of this paper are: gr-qc
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The categories of this paper are: q-bio
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The categories of this paper are: dg-ga
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The categories of this paper are: bayes-an
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The categories of this paper are: adap-org
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The categories of this paper are: cond-mat
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-ex
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The categories of this paper are: cmp-lg
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The categories of this paper are: comp-gas
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The categories of this paper are: supr-con
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The categories of this paper are: ao-sci
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The categories of this paper are: q-fin
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The categories of this paper are: alg-geom
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The categories of this paper are: nlin
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The categories of this paper are: hep-lat