Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetic Fields and Infall Motions in NGC 1333 IRAS 4   We present single-dish 350 micron dust continuum polarimetry as well as HCN
and HCO+ J=4-3 rotational emission spectra obtained on NGC 1333 IRAS 4. The
polarimetry indicates a uniform field morphology over a 20" radius from the
peak continuum flux of IRAS 4A, in agreement with models of magnetically
supported cloud collapse. The field morphology around IRAS 4B appears to be
quite distinct however, with indications of depolarization observed towards the
peak flux of this source. Inverse P-Cygni profiles are observed in the HCN
J=4-3 line spectra towards IRAS 4A, providing a clear indication of infall gas
motions. Taken together, the evidence gathered here appears to support the
scenario that IRAS 4A is a cloud core in a critical state of support against
gravitational collapse.

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The categories of this paper are: mtrl-th
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The categories of this paper are: patt-sol
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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: hep-lat
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The categories of this paper are: math-ph
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The categories of this paper are: chem-ph
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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: comp-gas
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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: hep-th
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The categories of this paper are: nucl-th
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The categories of this paper are: cs
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The categories of this paper are: cmp-lg