Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Open clusters in the Third Galactic Quadrant. II. The intermediate age
  open clusters NGC 2425 and NGC 2635   We analyse CCD broad band (UBV(RI)c) photometric data obtained in the fields
of the poorly studied open clusters NGC 2425 and NGC 2635. Both clusters are
found to be of intermediate age thus increasing the population of open clusters
known to be of the age of, or older than, the Hyades. More explicitly, we find
that NGC 2425 is a 2.2 Gyr old cluster, probably of solar metallicity, located
at 3.5 kpc from the Sun. NGC 2635 is a Hyades age (600 Myr) cluster located at
a distance of 4.0 kpc from the Sun. Its Colour Magnitude Diagram reveals that
it is extremely metal poor for its age and position, thus making it a very
interesting object in the context of Galactic Disk chemical evolution models.

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The categories of this paper are: cs
23
The categories of this paper are: solv-int
22
The categories of this paper are: chao-dyn
10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
25
The categories of this paper are: patt-sol
34
The categories of this paper are: chem-ph
12
The categories of this paper are: nucl-th
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat
5
The categories of this paper are: gr-qc
36
The categories of this paper are: cmp-lg