Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Detection of the 205 um [NII] Line from the Carina Nebula   We report the first detection of the 205 um 3P1 - 3P0 [NII] line from a
ground-based observatory using a direct detection spectrometer. The line was
detected from the Carina star formation region using the South Pole Imaging
Fabry-Perot Interferometer (SPIFI) on the Antarctic Submillimeter Telescope and
Remote Observatory (AST/RO) at South Pole. The [NII] 205 um line strength
indicates a low-density (n ~ 32 cm^-3 ionized medium, similar to the
low-density ionized halo reported previously in its [OIII] 52 and 88 um line
emission. When compared with the ISO [CII] observations of this region, we find
that ~27% of the [CII] line emission arises from this low-density ionized gas,
but the large majority ~ 73% of the observed [CII] line emission arises from
the neutral interstellar medium. This result supports and underpins prior
conclusions that most of the observed [CII] 158 um line emission from Galactic
and extragalactic sources arises from the warm, dense photodissociated surfaces
of molecular clouds. The detection of the [NII] line demonstrates the utility
of Antarctic sites for THz spectroscopy.

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The categories of this paper are: acc-phys
3
The categories of this paper are: physics
23
The categories of this paper are: solv-int
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
13
The categories of this paper are: quant-ph
32
The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
27
The categories of this paper are: comp-gas
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-th
34
The categories of this paper are: chem-ph