Reaction rates for O-18(alpha, gamma)Ne-22, Ne-22(alpha, gamma)Mg-26, and Ne-22(alpha, n)Mg-25 in stellar helium burning and s-process nucleosynthesis in massive stars

Abstract

view Abstract Citations (135) References (50) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Reaction Rates for 18O( alpha , gamma ) 22Ne, 22Ne( alpha , gamma ) 26Mg, and 22Ne( alpha , n) 25Mg in Stellar Helium Burning and s-Process Nucleosynthesis in Massive Stars Kaeppeler, F. ; Wiescher, M. ; Giesen, U. ; Goerres, J. ; Baraffe, I. ; El Eid, M. ; Raiteri, C. M. ; Busso, M. ; Gallino, R. ; Limongi, M. ; Chieffi, A. Abstract New experimental results in O-18(Li-6, d) and Ne-22(Li-6, d) alpha transfer reaction studies have been utilized to calculate the resonance strength of low-energy resonances in the alpha-capture on O-18 and Ne-22. The present results imply a significant increase of the reaction rates for O-18(alpha, gamma)Ne-22 and Ne-22(alpha, gamma)Mg-26. The Ne-22(alpha, n)Mg-25 rate might be strongly enhanced by a possible resonance at 633 keV. The respective uncertainties are presented as a function of temperature. The influence of the proposed reaction rates on the s-process nucleosynthesis during core helium burning has been investigated in the range 15 less than M/solar mass less than 30. The resulting uncertainties are compared to those related to the modeling of core helium burning in massive stars. This comparison indicates that the s-process may be a useful constraint for the evolution and convection in massive stars, provided the persistent problem of the 633 keV resonance in the Ne-22(alpha, n)Mg-25 channel can be solved. Publication: The Astrophysical Journal Pub Date: December 1994 DOI: 10.1086/175004 Bibcode: 1994ApJ...437..396K Keywords: Early Stars; Massive Stars; Nuclear Fusion; Reaction Kinetics; Stellar Evolution; Stellar Interiors; Stellar Models; Stellar Physics; Convective Flow; Helium; Mathematical Models; Astrophysics; NUCLEAR REACTIONS; NUCLEOSYNTHESIS; ABUNDANCES; STARS: EARLY-TYPE; STARS: INTERIORS full text sources ADS |