Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A New Challenge: Bar Formation and Secular Evolution in Lenticular
  Galaxies   To further enhance our understanding on the formation and evolution of bars
in lenticular (S0) galaxies, we are undertaking a detailed photometric and
spectroscopic study on a sample of 22 objects. Here we report the results of a
2D structural analysis on two barred face-on S0's, which indicate that
presently these galaxies do not possess disks. We discuss two possibilities to
explain these surprising results, namely strong secular evolution and bar
formation without disks.

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The categories of this paper are: q-bio
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The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
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The categories of this paper are: dg-ga
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: atom-ph
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The categories of this paper are: econ
4
The categories of this paper are: cond-mat
8
The categories of this paper are: hep-ex
16
The categories of this paper are: stat
3
The categories of this paper are: physics
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The categories of this paper are: eess