The effect of 12C +12C rate uncertainties on the evolution and nucleosynthesis of massive stars

M. E. Bennett, R. Hirschi, M. Pignatari, S. Diehl, C. Fryer, F. Herwig, A. Hungerford, K. Nomoto, G. Rockefeller, Francis Timmes, M. Wiescher

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

Over the last 40 years, the 12C +12C fusion reaction has been the subject of considerable experimental efforts to constrain uncertainties at temperatures relevant for stellar nucleosynthesis. Recent studies have indicated that the reaction rate may be higher than that currently used in stellar models. In order to investigate the effect of an enhanced carbon-burning rate on massive star structure and nucleosynthesis, new stellar evolution models and their yields are presented exploring the impact of three different 12C +12C reaction rates. Non-rotating stellar models considering five different initial masses, 15, 20, 25, 32 and 60 M, at solar metallicity, were generated using the Geneva Stellar Evolution Code (genec) and were later post-processed with the NuGrid Multi-zone Post-Processing Network tool (mppnp). A dynamic nuclear reaction network of ~1100 isotopes was used to track the s-process nucleosynthesis. An enhanced 12C +12C reaction rate causes core carbon burning to be ignited more promptly and at lower temperature. This reduces the neutrino losses, which increases the core carbon-burning lifetime. An increased carbon-burning rate also increases the upper initial mass limit for which a star exhibits a convective carbon core (rather than a radiative one). Carbon-shell burning is also affected, with fewer convective-shell episodes and convection zones that tend to be larger in mass. Consequently, the chance of an overlap between the ashes of carbon-core burning and the following carbon shell convection zones is increased, which can cause a portion of the ashes of carbon-core burning to be included in the carbon shell. Therefore, during the supernova explosion, the ejecta will be enriched by s-process nuclides synthesized from the carbon-core s-process. The yields were used to estimate the weak s-process component in order to compare with the Solar system abundance distribution. The enhanced rate models were found to produce a significant proportion of Kr, Sr, Y, Zr, Mo, Ru, Pd and Cd in the weak component, which is primarily the signature of the carbon-core s-process. Consequently, it is shown that the production of isotopes in the Kr-Sr region can be used to constrain the 12C +12C rate using the current branching ratio for α- and p-exit channels.

Original languageEnglish (US)
Pages (from-to)3047-3070
Number of pages24
JournalMonthly Notices of the Royal Astronomical Society
Volume420
Issue number4
DOIs
StatePublished - Mar 2012

Fingerprint

massive stars
nuclear fusion
carbon
reaction rate
shell
burning rate
reaction kinetics
stellar models
stellar evolution
ashes
rate
effect
convection
ash
isotopes
isotope
causes
ejecta
nuclides
nuclear reactions

Keywords

  • Nuclear reactions, nucleosynthesis, abundances
  • Stars: abundances
  • Stars: evolution

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

The effect of 12C +12C rate uncertainties on the evolution and nucleosynthesis of massive stars. / Bennett, M. E.; Hirschi, R.; Pignatari, M.; Diehl, S.; Fryer, C.; Herwig, F.; Hungerford, A.; Nomoto, K.; Rockefeller, G.; Timmes, Francis; Wiescher, M.

In: Monthly Notices of the Royal Astronomical Society, Vol. 420, No. 4, 03.2012, p. 3047-3070.

Research output: Contribution to journalArticle

Bennett, ME, Hirschi, R, Pignatari, M, Diehl, S, Fryer, C, Herwig, F, Hungerford, A, Nomoto, K, Rockefeller, G, Timmes, F & Wiescher, M 2012, 'The effect of 12C +12C rate uncertainties on the evolution and nucleosynthesis of massive stars', Monthly Notices of the Royal Astronomical Society, vol. 420, no. 4, pp. 3047-3070. https://doi.org/10.1111/j.1365-2966.2012.20193.x
Bennett, M. E. ; Hirschi, R. ; Pignatari, M. ; Diehl, S. ; Fryer, C. ; Herwig, F. ; Hungerford, A. ; Nomoto, K. ; Rockefeller, G. ; Timmes, Francis ; Wiescher, M. / The effect of 12C +12C rate uncertainties on the evolution and nucleosynthesis of massive stars. In: Monthly Notices of the Royal Astronomical Society. 2012 ; Vol. 420, No. 4. pp. 3047-3070.
@article{ee601b3c4d634b56897952580497dbf1,
title = "The effect of 12C +12C rate uncertainties on the evolution and nucleosynthesis of massive stars",
abstract = "Over the last 40 years, the 12C +12C fusion reaction has been the subject of considerable experimental efforts to constrain uncertainties at temperatures relevant for stellar nucleosynthesis. Recent studies have indicated that the reaction rate may be higher than that currently used in stellar models. In order to investigate the effect of an enhanced carbon-burning rate on massive star structure and nucleosynthesis, new stellar evolution models and their yields are presented exploring the impact of three different 12C +12C reaction rates. Non-rotating stellar models considering five different initial masses, 15, 20, 25, 32 and 60 M⊙, at solar metallicity, were generated using the Geneva Stellar Evolution Code (genec) and were later post-processed with the NuGrid Multi-zone Post-Processing Network tool (mppnp). A dynamic nuclear reaction network of ~1100 isotopes was used to track the s-process nucleosynthesis. An enhanced 12C +12C reaction rate causes core carbon burning to be ignited more promptly and at lower temperature. This reduces the neutrino losses, which increases the core carbon-burning lifetime. An increased carbon-burning rate also increases the upper initial mass limit for which a star exhibits a convective carbon core (rather than a radiative one). Carbon-shell burning is also affected, with fewer convective-shell episodes and convection zones that tend to be larger in mass. Consequently, the chance of an overlap between the ashes of carbon-core burning and the following carbon shell convection zones is increased, which can cause a portion of the ashes of carbon-core burning to be included in the carbon shell. Therefore, during the supernova explosion, the ejecta will be enriched by s-process nuclides synthesized from the carbon-core s-process. The yields were used to estimate the weak s-process component in order to compare with the Solar system abundance distribution. The enhanced rate models were found to produce a significant proportion of Kr, Sr, Y, Zr, Mo, Ru, Pd and Cd in the weak component, which is primarily the signature of the carbon-core s-process. Consequently, it is shown that the production of isotopes in the Kr-Sr region can be used to constrain the 12C +12C rate using the current branching ratio for α- and p-exit channels.",
keywords = "Nuclear reactions, nucleosynthesis, abundances, Stars: abundances, Stars: evolution",
author = "Bennett, {M. E.} and R. Hirschi and M. Pignatari and S. Diehl and C. Fryer and F. Herwig and A. Hungerford and K. Nomoto and G. Rockefeller and Francis Timmes and M. Wiescher",
year = "2012",
month = "3",
doi = "10.1111/j.1365-2966.2012.20193.x",
language = "English (US)",
volume = "420",
pages = "3047--3070",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "4",

}

TY - JOUR

T1 - The effect of 12C +12C rate uncertainties on the evolution and nucleosynthesis of massive stars

AU - Bennett, M. E.

AU - Hirschi, R.

AU - Pignatari, M.

AU - Diehl, S.

AU - Fryer, C.

AU - Herwig, F.

AU - Hungerford, A.

AU - Nomoto, K.

AU - Rockefeller, G.

AU - Timmes, Francis

AU - Wiescher, M.

PY - 2012/3

Y1 - 2012/3

N2 - Over the last 40 years, the 12C +12C fusion reaction has been the subject of considerable experimental efforts to constrain uncertainties at temperatures relevant for stellar nucleosynthesis. Recent studies have indicated that the reaction rate may be higher than that currently used in stellar models. In order to investigate the effect of an enhanced carbon-burning rate on massive star structure and nucleosynthesis, new stellar evolution models and their yields are presented exploring the impact of three different 12C +12C reaction rates. Non-rotating stellar models considering five different initial masses, 15, 20, 25, 32 and 60 M⊙, at solar metallicity, were generated using the Geneva Stellar Evolution Code (genec) and were later post-processed with the NuGrid Multi-zone Post-Processing Network tool (mppnp). A dynamic nuclear reaction network of ~1100 isotopes was used to track the s-process nucleosynthesis. An enhanced 12C +12C reaction rate causes core carbon burning to be ignited more promptly and at lower temperature. This reduces the neutrino losses, which increases the core carbon-burning lifetime. An increased carbon-burning rate also increases the upper initial mass limit for which a star exhibits a convective carbon core (rather than a radiative one). Carbon-shell burning is also affected, with fewer convective-shell episodes and convection zones that tend to be larger in mass. Consequently, the chance of an overlap between the ashes of carbon-core burning and the following carbon shell convection zones is increased, which can cause a portion of the ashes of carbon-core burning to be included in the carbon shell. Therefore, during the supernova explosion, the ejecta will be enriched by s-process nuclides synthesized from the carbon-core s-process. The yields were used to estimate the weak s-process component in order to compare with the Solar system abundance distribution. The enhanced rate models were found to produce a significant proportion of Kr, Sr, Y, Zr, Mo, Ru, Pd and Cd in the weak component, which is primarily the signature of the carbon-core s-process. Consequently, it is shown that the production of isotopes in the Kr-Sr region can be used to constrain the 12C +12C rate using the current branching ratio for α- and p-exit channels.

AB - Over the last 40 years, the 12C +12C fusion reaction has been the subject of considerable experimental efforts to constrain uncertainties at temperatures relevant for stellar nucleosynthesis. Recent studies have indicated that the reaction rate may be higher than that currently used in stellar models. In order to investigate the effect of an enhanced carbon-burning rate on massive star structure and nucleosynthesis, new stellar evolution models and their yields are presented exploring the impact of three different 12C +12C reaction rates. Non-rotating stellar models considering five different initial masses, 15, 20, 25, 32 and 60 M⊙, at solar metallicity, were generated using the Geneva Stellar Evolution Code (genec) and were later post-processed with the NuGrid Multi-zone Post-Processing Network tool (mppnp). A dynamic nuclear reaction network of ~1100 isotopes was used to track the s-process nucleosynthesis. An enhanced 12C +12C reaction rate causes core carbon burning to be ignited more promptly and at lower temperature. This reduces the neutrino losses, which increases the core carbon-burning lifetime. An increased carbon-burning rate also increases the upper initial mass limit for which a star exhibits a convective carbon core (rather than a radiative one). Carbon-shell burning is also affected, with fewer convective-shell episodes and convection zones that tend to be larger in mass. Consequently, the chance of an overlap between the ashes of carbon-core burning and the following carbon shell convection zones is increased, which can cause a portion of the ashes of carbon-core burning to be included in the carbon shell. Therefore, during the supernova explosion, the ejecta will be enriched by s-process nuclides synthesized from the carbon-core s-process. The yields were used to estimate the weak s-process component in order to compare with the Solar system abundance distribution. The enhanced rate models were found to produce a significant proportion of Kr, Sr, Y, Zr, Mo, Ru, Pd and Cd in the weak component, which is primarily the signature of the carbon-core s-process. Consequently, it is shown that the production of isotopes in the Kr-Sr region can be used to constrain the 12C +12C rate using the current branching ratio for α- and p-exit channels.

KW - Nuclear reactions, nucleosynthesis, abundances

KW - Stars: abundances

KW - Stars: evolution

UR - http://www.scopus.com/inward/record.url?scp=84857647065&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84857647065&partnerID=8YFLogxK

U2 - 10.1111/j.1365-2966.2012.20193.x

DO - 10.1111/j.1365-2966.2012.20193.x

M3 - Article

AN - SCOPUS:84857647065

VL - 420

SP - 3047

EP - 3070

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 4

ER -