Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Limits on the HI content of the dwarf galaxy Hydra II   Sensitive 21cm HI observations have been made with the Green Bank Telescope
toward the newly-discovered Local Group dwarf galaxy Hydra II, which may lie
within the leading arm of the Magellanic Stream. No neutral hydrogen was
detected. Our 5-sigma limit of MHI < 210 solar masses for a 15 km/s linewidth
gives a gas-to-luminosity ratio MHI/L_V < 2.6 x 10^{-2} Mo / Lo. The limits on
HI mass and MHI/L_V are typical of dwarf galaxies found within a few hundred
kpc of the Milky Way. Whatever the origin of Hydra II, its neutral gas
properties are not unusual.

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The categories of this paper are: econ
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The categories of this paper are: bayes-an
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The categories of this paper are: q-fin
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The categories of this paper are: supr-con
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The categories of this paper are: nucl-ex
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The categories of this paper are: alg-geom
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The categories of this paper are: math
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The categories of this paper are: q-alg
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The categories of this paper are: solv-int
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The categories of this paper are: plasm-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: cs
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The categories of this paper are: hep-lat
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The categories of this paper are: patt-sol
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-th