Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Galaxy mapping with the SAURON integral-field spectrograph: The star
  formation history of NGC 4365   We report the first wide-field mapping of the kinematics and stellar
populations in the E3 galaxy NGC 4365. The velocity maps extend previous
long-slit work. They show two independent kinematic subsystems: the central 300
x 700 pc rotates about the projected minor axis, and the main body of the
galaxy, 3 x 4 kpc, rotates almost at right angles to this. The line-strength
maps show that the metallicity of the stellar population decreases from a
central value greater than solar, to one-half solar at a radius of 2 kpc. The
decoupled core and main body of the galaxy have the same luminosity-weighted
age, of ~14 Gyr, and the same elevated magnesium-to-iron ratio. The two
kinematically distinct components have thus shared a common star formation
history. We infer that the galaxy underwent a sequence of mergers associated
with dissipative star formation that ended >12 Gyr ago. The misalignment
between the photometric and kinematic axes of the main body is unambiguous
evidence of triaxiality. The similarity of the stellar populations in the two
components suggests that the observed kinematic structure has not changed
substantially in 12 Gyr.

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The categories of this paper are: acc-phys
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The categories of this paper are: eess
27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
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The categories of this paper are: nucl-ex
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The categories of this paper are: patt-sol
3
The categories of this paper are: physics
13
The categories of this paper are: quant-ph
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The categories of this paper are: q-fin
1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph
12
The categories of this paper are: nucl-th
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The categories of this paper are: alg-geom
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The categories of this paper are: solv-int
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The categories of this paper are: q-bio
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The categories of this paper are: plasm-ph