Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Shocks and Star Formation in Stephan's Quintet. I. Gemini Spectroscopy
  of H{\alpha}-bright knots   We present a Gemini-GMOS spectroscopic study of HST-selected
H{\alpha}-emitting regions in Stephan's Quintet (HCG 92), a nearby compact
galaxy group, with the aim of disentangling the processes of shock-induced
heating and star formation in its intra-group medium. The $\approx$40 sources
are distributed across the system, but most densely concentrated in the
$\sim$kpc-long shock region. Their spectra neatly divide them into narrow- and
and broad-line emitters, and we decompose the latter into three or more
emission peaks corresponding to spatial elements discernible in HST imaging.
The emission line ratios of the two populations of H{\alpha}-emitters confirm
their nature as H II regions (90% of the sample) or molecular gas heated by a
shock-front propagating at $\lesssim$300 km/s. Their redshift distribution
reveals interesting three-dimensional structure with respect to gas-phase
baryons, with no H II regions associated with shocked gas, no shocked regions
in the intruder galaxy NGC 7318B, and a sharp boundary between shocks and star
formation. We conclude that star formation is inhibited substantially, if not
entirely, in the shock region. Attributing those H II regions projected against
the shock to the intruder, we find a lopsided distribution of star formation in
this galaxy, reminiscent of pile-up regions in models of interacting galaxies.
The H{\alpha} luminosities imply mass outputs, star formation rates, and
efficiencies similar to nearby star-forming regions. Two large knots are an
exception to this, being comparable in stellar output to the prolific 30
Doradus region. We also examine Stephan's Quintet in the context of compact
galaxy group evolution, as a paradigm for intermittent star formation histories
in the presence of a rich, X-ray emitting intra-group medium.

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The categories of this paper are: funct-an
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The categories of this paper are: q-bio
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The categories of this paper are: supr-con
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The categories of this paper are: solv-int
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The categories of this paper are: eess
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The categories of this paper are: alg-geom
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The categories of this paper are: q-alg
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The categories of this paper are: hep-lat
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The categories of this paper are: cs
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The categories of this paper are: econ
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The categories of this paper are: hep-ex
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The categories of this paper are: nlin
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The categories of this paper are: gr-qc
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The categories of this paper are: chao-dyn
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The categories of this paper are: dg-ga
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The categories of this paper are: quant-ph