Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Major Substructure in the M31 Outer Halo: Distances and Metallicities
  along the Giant Stellar Stream   We present a renewed look at M31's Giant Stellar Stream along with the nearby
structures Stream C and Stream D, exploiting a new algorithm capable of fitting
to the red giant branch (RGB) of a structure in both colour and magnitude
space. Using this algorithm, we are able to generate probability distributions
in distance, metallicity and RGB width for a series of subfields spanning these
structures. Specifically, we confirm a distance gradient of approximately 20
kpc per degree along a 6 degree extension of the Giant Stellar Stream, with the
farthest subfields from M31 lying ~ 120 kpc more distant than the inner-most
subfields. Further, we find a metallicity that steadily increases from
-0.7^{+0.1}_{-0.1} dex to -0.2^{+0.2}_{-0.1} dex along the inner half of the
stream before steadily dropping to a value of -1.0^{+0.2}_{-0.2} dex at the
farthest reaches of our coverage. The RGB width is found to increase rapidly
from 0.4^{+0.1}_{-0.1} dex to 1.1^{+0.2}_{-0.1} dex in the inner portion of the
stream before plateauing and decreasing marginally in the outer subfields of
the stream. In addition, we estimate Stream C to lie at a distance between 794
and 862 kpc and Stream D between 758 kpc and 868 kpc. We estimate the median
metallicity of Stream C to lie in the range -0.7 to -1.6 dex and a metallicity
of -1.1^{+0.3}_{-0.2} dex for Stream D. RGB widths for the two structures are
estimated to lie in the range 0.4 to 1.2 dex and 0.3 to 0.7 dex respectively.
In total, measurements are obtained for 19 subfields along the Giant Stellar
Stream, 4 along Stream C, 5 along Stream D and 3 general M31 spheroid fields
for comparison. We thus provide a higher resolution coverage of the structures
in these parameters than has previously been available in the literature.

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The categories of this paper are: mtrl-th
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The categories of this paper are: math-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: funct-an
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The categories of this paper are: adap-org
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The categories of this paper are: nucl-th
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The categories of this paper are: cond-mat
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The categories of this paper are: econ
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The categories of this paper are: q-alg
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The categories of this paper are: atom-ph
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The categories of this paper are: cs
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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: hep-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: quant-ph