Context: Ogata et al. (2009, Progr. Theor. Phys., 122, 1055) presented a theoretical determination of the ^4He(αα,γ)12C, or triple-α, nuclear reaction rate. Their rate differs from the NACRE rate by many orders of magnitude at temperatures relevant for low mass stars.
Aims: We explore the evolutionary implications of adopting the OKK triple-α reaction rate in low mass stars and compare the results with those obtained using the NACRE rate.
Methods: The triple-α reaction rates are compared by following the evolution of stellar models at 1 and 1.5 M⊙ with Z = 0.0002 and Z = 0.02.
Results: Results show that the OKK rate has severe consequences for the late stages of stellar evolution in low mass stars. Most notable is the shortening-or disappearance-of the red giant phase.
Conclusions: The OKK triple-α reaction rate is incompatible with observations of extended red giant branches and He burning stars in old stellar systems.
Astronomy and Astrophysics
- Pub Date:
- December 2009
- nuclear reactions;
- stars: evolution;
- stars: Hertsprung-Russell (HR) and C-M diagrams;
- Astrophysics - Solar and Stellar Astrophysics
- Prepared as an A&