Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Broad-Band Imaging of a Large Sample of Irregular Galaxies   We present the results of UBV imaging of a large sample of irregular
galaxies: 94 Im systems, 24 Blue Compact Dwarfs (BCDs), and 18 Sm galaxies. We
also include JHK imaging of 41 of these galaxies. The sample spans a large
range in galactic parameters. Ellipse fit axial ratios, inclinations, and
position angles are derived, integrated photometry and azimuthally-averaged
surface photometry profiles are determined, and exponential fits give the
central surface brightnesses, scale lengths, and isophotal and half-power
radii. These data are used to address the shapes of Im galaxies, look for clues
to past interactions in large-scale peculiarities, examine the nature and
consequences of bars, study color gradients and large-scale color variations,
and compare the exponential disk profiles of the young and old stellar
components. For example, color gradients exhibit a great variety and not all
passbands are correlated. Bars are associated with higher star formation rates.
Many irregulars show a double exponential radial light profile that is steeper
in the outer parts, and these are reproduced by a new model of star formation
that is discussed in a companion paper. Some galaxies, primarily BCDs, have
double exponentials that are steeper (and bluer) in the inner parts, presumably
from centralized star formation. Im-types have thicker, less-prominent dust
layers than spiral galaxies because of their lower average surface densities
and midplane extinctions.

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The categories of this paper are: ao-sci
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The categories of this paper are: mtrl-th
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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: bayes-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: gr-qc
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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: math-ph
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The categories of this paper are: stat
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The categories of this paper are: physics
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The categories of this paper are: comp-gas
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The categories of this paper are: nucl-th
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The categories of this paper are: cond-mat