Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The R Stars: Carbon Stars of a Different Kind   After 16 years of radial-velocity observations of a sample of 22 R-type
carbon stars, no evidence for binary motion has been detected in any of them.
This is surprising considering that approximately 20% of normal late-type
giants are spectroscopic binaries, and the fraction is close to 100% in barium,
CH, and subgiant/dwarf CH and barium stars. It is suggested, therefore, that a
process that has caused the mixing of carbon to the surface of these stars
cannot act in a wide binary system. Possibly, the R stars were once all
binaries, but with separations that would not allow them to evolve completely
up the giant and asymptotic giant branchs without coalescing. This coalescence
may be the agent which causes carbon produced in the helium-core flash to be
mixed outwards to a region where convection zones can bring it to the surface
of the star.

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The categories of this paper are: q-alg
21
The categories of this paper are: adap-org
3
The categories of this paper are: physics
24
The categories of this paper are: dg-ga
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The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: mtrl-th
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The categories of this paper are: gr-qc
1
The categories of this paper are: cs
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The categories of this paper are: math-ph
2
The categories of this paper are: math
13
The categories of this paper are: quant-ph
0
The categories of this paper are: hep-ph
20
The categories of this paper are: acc-phys