Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Characterizing the velocity field in hydrodynamical simulations of
  low-mass star formation using spectral line profiles   When low-mass stars form, the collapsing cloud of gas and dust goes through
several stages which are usually characterized by the shape of their spectral
energy distributions. Such classification is based on the cloud morphology only
and does not address the dynamical state of the object. In this paper we
investigate the initial cloud collapse and subsequent disk formation through
the dynamical behavior as reflected in the sub-millimeter spectral emission
line profiles. If a young stellar object is to be characterized by its
dynamical structure it is important to know how accurately information about
the velocity field can be extracted and which observables provide the best
description of the kinematics. Of particular interest is the transition from
infalling envelope to rotating disk, because this provides the initial
conditions for the protoplanetary disk, such as mass and size. We use a
hydrodynamical model, describing the collapse of a core and formation of a
disk, to produce synthetic observables which we compare to calculated line
profiles of a simple parameterized model. Because we know the velocity field
from the hydrodynamical simulation we can determine in a quantitative way how
well our best-fit parameterized velocity field reproduces the original. We use
a molecular line excitation and radiation transfer code to produce spectra of
both our hydro dynamical simulation as well as our parameterized model. We find
that information about the velocity field can reasonably well be derived by
fitting a simple model to either single-dish lines or interferometric data, but
preferentially by using a combination of the two. Our result shows that it is
possible to establish relative ages of a sample of young stellar objects using
this method, independently of the details of the hydrodynamical model.

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The categories of this paper are: hep-ex
18
The categories of this paper are: econ
1
The categories of this paper are: cs
17
The categories of this paper are: q-fin
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The categories of this paper are: adap-org
27
The categories of this paper are: comp-gas
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The categories of this paper are: alg-geom
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The categories of this paper are: dg-ga
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The categories of this paper are: math-ph
3
The categories of this paper are: physics
31
The categories of this paper are: ao-sci
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The categories of this paper are: hep-lat
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The categories of this paper are: cmp-lg
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The categories of this paper are: quant-ph
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The categories of this paper are: funct-an
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The categories of this paper are: chem-ph