Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: HCO+ and radio continuum emission from the star forming region
  G75.78+0.34   We present 1.3 and 3.6cm radio continuum images and a HCO+ spectrum of the
massive star forming region G75.78+0.34 obtained with the Very Large Array
(VLA) and with the Berkley Illinois Maryland Association (BIMA) interferometer.
Three structures were detected in the continuum emission: one associated to the
well known cometary HII region, plus two more compact structures located at 6"
east and at 2" south of cometary HII region. Using the total flux and intensity
peak we estimated an electron density of ~1.5x10^4 cm^{-3}, an emission measure
of ~6x10^{7} cm^{-6} pc, a mass of ionized gas of ~3 M_Sun and a diameter of
0.05 pc for the cometary HII region, being typical values for an ultracompact
HII region. The HCO^+ emission is probably originated from the molecular
outflows previously observed in HCN and CO.

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The categories of this paper are: hep-ex
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The categories of this paper are: q-fin
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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: acc-phys
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The categories of this paper are: atom-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: solv-int
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The categories of this paper are: ao-sci
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The categories of this paper are: supr-con
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The categories of this paper are: cs
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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: comp-gas
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The categories of this paper are: eess
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The categories of this paper are: stat