Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Discovery of technetium- and niobium-rich S stars: the case for
  bitrinsic stars   S stars are late-type giants with overabundances of s-process elements. They
come in two flavours depending on the presence or not of technetium (Tc), an
element without stable isotopes. Intrinsic S stars are Tc-rich and genuine
asymptotic giant branch (AGB)stars while extrinsic S stars owe their s-process
overabundances to the pollution from a former AGB companion, now a white
dwarf(WD). In addition to Tc, another distinctive feature between intrinsic and
extrinsic S stars is the overabundance of niobium (Nb) in the latter class. We
discuss the case of the S stars BD+79 156 and o1Ori whose specificity is to
share the distinctive features of both intrinsic and extrinsic S stars, namely
the presence of Tc along with a Nb overabundance. BD+79 156 is the first clear
case of a bitrinsic star, i.e. a doubly s-process-enriched object, first
through mass transfer in a binary system, and then through internal
nucleosynthesis (responsible for the Tc-enrichment in BD+79 156 which must
therefore have reached the AGB phase of its evolution). This hybrid nature of
the s-process pattern in BD+79 156 is supported by its binary nature and its
location in the HR diagram just beyond the onset of the third dredge-up on the
AGB. The Tc-rich, binary S-star o1Ori with a WD companion was another
long-standing candidate for a similar hybrid s-process enrichment. However the
marginal overabundance of Nb derived ino1Ori does not allow to trace
unambiguously the evidence of a large pollution coming from the AGB progenitor
of its current WD companion. As a side product, the current study offers a new
way of detecting binary AGB stars with WD companions by identifying their
Tc-rich nature along with a Nb overabundance.

22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
4
The categories of this paper are: cond-mat
31
The categories of this paper are: ao-sci
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
36
The categories of this paper are: cmp-lg
10
The categories of this paper are: q-bio
14
The categories of this paper are: math-ph
13
The categories of this paper are: quant-ph
23
The categories of this paper are: solv-int
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an