Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the oxygen abundances of M 67 stars from the turn-off point through
  the red-giant branch   With an aim to examine whether the surface oxygen composition suffers any
appreciable change due to evolution-induced mixing of nuclear-processed
material in the envelope of red giants, abundance determinations for O/Fe/Ni
based on the synthetic spectrum-fitting method were performed by using the
moderate-dispersion spectra in the 7770-7792A region (comprising O I 7771-5, Fe
I 7780, and Ni I 7788 lines) for 16 stars of the old open cluster M 67 in
various evolutionary stages from the turn-off point through the red giant
branch. We could not find any meaningful difference in the oxygen abundances
between the non-giant group (T_eff > 5000 K) and the red-giant group (T_eff <
5000 K), which are almost consistent with each other on the average (despite
that both have rather large dispersions of a few tenths dex caused by
insufficient data quality), though only one giant star (S 1054) appears to show
an exceptionally low O abundance and thus needs a more detailed study. This
result may suggest that oxygen content in the stellar envelope is hardly
affected (or changes are insignificant) by the mixing of H-burning products in
the red-giant phase, as far as M 67 stars of low mass (~1.3 M_sun) are
concerned, which is consistent with the prediction from the conventional
stellar evolution theory of first dredge-up.

2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
24
The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
28
The categories of this paper are: alg-geom
21
The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
4
The categories of this paper are: cond-mat