The CNO Isotopes: Deep Circulation in Red Giants and First and Second Dredge-up

@article{Boothroyd1995TheCI,
  title={The CNO Isotopes: Deep Circulation in Red Giants and First and Second Dredge-up},
  author={Arnold I. Boothroyd and I. Juliana Sackmann},
  journal={The Astrophysical Journal},
  year={1995},
  volume={510},
  pages={232-250}
}
It is demonstrated that deep circulation mixing below the base of the standard convective envelope, and the consequent "cool bottom processing" (CBP) of the CNO isotopes, can reproduce the trend with stellar mass of the 12C/13C observations in low-mass red giants. (This trend is opposite to what is expected from standard first dredge-up.) Our models assume that extra mixing always reaches to the same distance in temperature from the H-burning shell and that CBP begins when the H-burning shell… 
ON THE NEED FOR DEEP-MIXING IN ASYMPTOTIC GIANT BRANCH STARS OF LOW MASS
The photospheres of low-mass red giants show CNO isotopic abundances that are not satisfactorily accounted for by canonical stellar models. The same is true for the measurements of these isotopes and
Nucleosynthesis and Mixing on the Asymptotic Giant Branch. III. Predicted and Observed s-Process Abundances
We present the results of s-process nucleosynthesis calculations for asymptotic giant branch (AGB) stars of different metallicities and different initial stellar masses (1.5 and 3 M☉), and we present
Understanding AGB Carbon Star Nucleosynthesis from Observations
Abstract Recent advances in the knowledge of the evolutionary status of asymptotic giant branch (AGB) stars and of the nucleosynthesis processes occurring in them are discussed, and used to interpret
Nucleosynthesis of Low and Intermediate-mass Stars
The asymptotic giant branch (AGB) is the last nuclear-burning phase for low and intermediate-mass stars with initial masses between about 0.8 to 8 solar masses. The AGB phase of evolution is very
Oxygen isotopic ratios in intermediate-mass red giants
Context. The abundances of the three main isotopes of oxygen are altered in the course of the CNO-cycle. When the first dredge-up mixes the burning products to the surface, the nucleosynthesis
Thermohaline mixing: a physical mechanism governing the photospheric composition of low-mass giants
Aims. Numerous spectroscopic observations provide compelling evidence for a non-canonical mixing process that modifies the surface abundances of Li, C and N of low-mass red giants when they reach the
Nucleosynthesis, Mixing Processes, and Gas Pollution from AGB Stars
We discuss the evolution of stars through the asymptotic giant branch, focusing on the physical mechanisms potentially able to alter the surface chemical composition and on how changes in the
Cool Bottom Processes on the Thermally Pulsing Asymptotic Giant Branch and the Isotopic Composition of Circumstellar Dust Grains
We examine the effects of cool bottom processing (CBP) on the isotopic ratios ^(18)O/^(16)O, ^(17)O/^(16)O, ^(14)N/^(15)N, ^(26)Al/^(27)Al, C/O, and N/O in the convective envelope during the
Which physics determines the location of the mean molecular weight minimum in red giants
Stars ascending the red giant branch develop an inversion in mean molecular weight (mu) owing to the burning of He-3 in the region immediately above their hydrogen-burning shells. This inversion may
The Dawes Review 2: Nucleosynthesis and Stellar Yields of Low- and Intermediate-Mass Single Stars
Abstract The chemical evolution of the Universe is governed by the chemical yields from stars, which in turn are determined primarily by the initial stellar mass. Even stars as low as 0.9 M⊙ can, at
...
1
2
3
4
5
...

References

SHOWING 1-10 OF 72 REFERENCES
Deep Circulation in Red Giant Stars: A Solution to the Carbon and Oxygen Isotope Puzzles?
The long-standing puzzle of low ^(12)C/^(13)C in low-mass red giant branch (RGB) stars, and the more recent puzzle of low ^(18)O/^(16)O ratios in asymptotic giant branch (AGB) stars and in
CNO abundances in Cepheids and supergiants: theoretical implications
Models of a 9 M/sub sun/ star have been evolved to see if the observed nitrogen enhancement and the carbon and oxygen depletions in yellow supergiants and Cepheids can be explained. In the standard
Meridional circulation and CNO anomalies in red giant stars
The possibility that meridional circulation due to internal rotation might lead to the mixing of CNO-processed material from the vicinity of the hydrogen shell into the envelope of a red giant star
PREDICTIONS OF OXYGEN ISOTOPE RATIOS IN STARS AND OF OXYGEN-RICH INTERSTELLAR GRAINS IN METEORITES
We carried out detailed, self-consistent calculations for stars from 1 to 9 M_☉ over a wide range of metallicities, following the evolution and nucleosynthesis from the pre-main sequence to the
Carbon isotope ratios along the giant branch of M67
The carbon isotope ratio in the giant branch stars of the open cluster M67 was studied in order to determine at what stage in the evolutionary sequence a star departs from standard evolution and
Sodium-oxygen abundance anticorrelations and deep-mixing scenarios for globular-cluster giants
We explore and extend the suggstion that 23Na might be produced in the interior of an evolving low-mass globular cluster giant and mixed to the surface (Kudryashov & Tutukov 1988, Denisenkov &
On the origin and evolution of isotopes of carbon, nitrogen, and oxygen
New calculations of CNO processing in stellar envelopes and other results from nucleosynthesis theory have been used as input to models for chemical evolution in the solar neighborhood. In contrast
Nucleosynthesis in massive stars and the 12C(α, γ)16O reaction rate
Oxygen isotopic abundances in evolved stars. IV. Five K giants
Oxygen isotopic ratios have been measured in the atmospheres of Alpha UMa, Beta Gem, Beta UMi, Alpha Ari, and Alpha Ser. It is shown that some of the stars in this and previous samples have probably
Carbon isotope ratios in field Population II giant stars
Carbon isotope ratios have been derived from high-resolution spectra of the CH G-band in 15 very metal-poor Population II giant stars and two similar dwarf stars. Many of the giants possess very low
...
1
2
3
4
5
...