Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: ALMA detection of dark chromospheric holes in the quiet Sun   We present Atacama Large Millimeter/submillimeter Array (ALMA) observations
of a quiet-Sun region at a wavelength of 3 mm, obtained during the first solar
ALMA cycle on April 27, 2017, and compare them with available chromospheric
observations in the UV and visible as well as with photospheric magnetograms.
ALMA images clearly reveal the presence of distinct particularly dark/cool
areas in the millimeter maps having temperatures as low as 60% of the normal
quiet Sun at 3 mm, which are not seen in the other data. We speculate that ALMA
is sensing cool chromospheric gas, whose presence had earlier been inferred
from infrared CO spectra.

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The categories of this paper are: math
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The categories of this paper are: econ
29
The categories of this paper are: funct-an
12
The categories of this paper are: nucl-th
35
The categories of this paper are: mtrl-th
36
The categories of this paper are: cmp-lg
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The categories of this paper are: hep-th
28
The categories of this paper are: alg-geom
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The categories of this paper are: nlin
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The categories of this paper are: hep-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: hep-ex
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The categories of this paper are: q-bio
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The categories of this paper are: dg-ga
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The categories of this paper are: cs
32
The categories of this paper are: atom-ph