Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Infrared stellar populations in the central parts of the Milky Way
  galaxy   Near- and mid-IR survey data from DENIS and ISOGAL are used to investigate
the structure and formation history of the inner 10 degree (1.4 kpc) of the
Milky Way galaxy. Synthetic bolometric corrections and extinction coefficients
in the near- and mid-IR are derived for stars of different spectral types, to
allow the transformation of theoretical isochrones into observable
colour-magnitude diagrams. The observed IR colour-magnitude diagrams are used
to derive the extinction, metallicity and age for individual stars. The inner
galaxy is dominated by an old population (> 7 Gyr). In addition, an
intermediate-age population (200 Myr to 7 Gyr) is detected, which is consistent
with the presence of a few hundred Asymptotic Giant Branch stars with heavy
mass loss. Furthermore, young stars (< 200 Myr) are found across the inner
Bulge. The metallicities of these stellar population components are discussed.
These results can be interpreted in terms of an early epoch of intense star
formation and chemical enrichment which shaped the bulk of the Bulge and
nucleus, and a more continuous star formation history which gradually shaped
the disk from the accretion of sub-solar metallicity gas from the halo. A
possible increase in star formation about 200 Myr ago might have been triggered
by a minor merger. Ever since the formation of the first stars, mechanisms have
been at play that mix the populations from the nucleus, Bulge and disk.
Luminosity functions across the inner galactic plane indicate the presence of
an inclined (bar) structure at > 1 kpc from the galactic centre, near the inner
Lindblad resonance. The innermost part of the Bulge, within about 1 kpc from
the galactic centre, seems azimuthally symmetric.

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The categories of this paper are: bayes-an
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The categories of this paper are: chem-ph
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The categories of this paper are: q-fin
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The categories of this paper are: nucl-ex
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The categories of this paper are: stat
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The categories of this paper are: chao-dyn
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The categories of this paper are: gr-qc
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The categories of this paper are: econ
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-th
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The categories of this paper are: adap-org
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The categories of this paper are: supr-con
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The categories of this paper are: math
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The categories of this paper are: nlin
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The categories of this paper are: ao-sci
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The categories of this paper are: cond-mat