Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evolved stars hint to an external origin of enhanced metallicity in
  planet-hosting stars   Exo-planets are preferentially found around high metallicity main sequence
stars. We aim at investigating whether evolved stars share this property, and
what this tells about planet formation. Statistical tools and the basic
concepts of stellar evolution theory are applied to published results as well
as our own radial velocity and chemical analyses of evolved stars. We show that
the metal distributions of planet-hosting (P-H) dwarfs and giants are
different, and that the latter do not favor metal-rich systems. Rather, these
stars follow the same age-metallicity relation as the giants without planets in
our sample. The straightforward explanation is to attribute the difference
between dwarfs and giants to the much larger masses of giants' convective
envelopes. If the metal excess on the main sequence is due to pollution, the
effects of dilution naturally explains why it is not observed among evolved
stars. Although we cannot exclude other explanations, the lack of any
preference for metal-rich systems among P-H giants could be a strong indication
of the accretion of metal-rich material. We discuss further tests, as well as
some predictions and consequences of this hypothesis.

32
The categories of this paper are: atom-ph
2
The categories of this paper are: math
25
The categories of this paper are: patt-sol
15
The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th
31
The categories of this paper are: ao-sci
28
The categories of this paper are: alg-geom
1
The categories of this paper are: cs
30
The categories of this paper are: q-alg
9
The categories of this paper are: nlin
27
The categories of this paper are: comp-gas
29
The categories of this paper are: funct-an
10
The categories of this paper are: q-bio
36
The categories of this paper are: cmp-lg
8
The categories of this paper are: hep-ex
13
The categories of this paper are: quant-ph