Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: The iron abundance in hot central stars of planetary nebulae derived
  from IUE spectra
29
The categories of this paper are: funct-an
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
5
The categories of this paper are: gr-qc
17
The categories of this paper are: q-fin
7
The categories of this paper are: hep-th
0
The categories of this paper are: hep-ph
20
The categories of this paper are: acc-phys
25
The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
26
The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
31
The categories of this paper are: ao-sci
28
The categories of this paper are: alg-geom
3
The categories of this paper are: physics