Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Evolution of the Multiplicity of Embedded Protostars II: Binary
  Separation Distribution & Analysis   We present the Class I protostellar binary separation distribution based on
the data tabulated in the companion paper. We verify the excess of Class I
binary stars over solar-type main-sequence stars, especially at separations
beyond 500 AU. Although our sources are in nearby star forming regions
distributed across the entire sky (including Orion), none of our objects are in
a high stellar density environment. The binary separation distribution changes
significantly during the Class I phase, and the binary frequency at separations
greater than 1000 AU declines steadily with respect to spectral index. Despite
these changes, the binary frequency remains constant until the end of the Class
I phase, when it drops sharply. We propose a scenario to account for the
changes in the Class I binary separation distribution. This scenario postulates
that companions with a separation greater than ~1000 AU were ejected during the
Class 0 phase, but remain gravitationally bound due to the mass of the
envelope. As the envelope dissipates, these companions become unbound and the
binary frequency at wide separations declines. This scenario predicts that a
large number of Class 0 objects should be non-hierarchical multiple systems,
and that many Class I YSOs with a widely separated companion should also have a
very close companion. We also find that Class I protostars are not dynamically
pristine, and have experienced dynamical evolution before they are visible as
Class I objects. For the first time, evidence is presented showing that the
Class I binary frequency and the binary separation distribution strongly depend
on the star forming environment. The reason for this dependence remains
unclear.

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The categories of this paper are: nucl-th
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-lat
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The categories of this paper are: econ
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The categories of this paper are: chem-ph
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The categories of this paper are: cs
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The categories of this paper are: atom-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: stat
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The categories of this paper are: cond-mat
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The categories of this paper are: math-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-bio
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The categories of this paper are: q-fin
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The categories of this paper are: cmp-lg