Low-temperature triple-alpha rate in a full three-body nuclear model

Area of Science:

• Nuclear Astrophysics
• Stellar Evolution
• Computational Physics

Background:

• The triple-alpha capture reaction is the primary source of carbon-12 (12C) in stars.
• Accurate reaction rates are essential for understanding stellar nucleosynthesis and evolution.
• Previous calculations involved approximations that may affect low-temperature rate predictions.

Purpose of the Study:

• To compute the triple-alpha capture reaction rate using a novel three-body method.
• To investigate the impact of pairwise Coulomb interactions on the reaction continuum.
• To compare the new rate with existing compilations and assess its effect on stellar models.

Main Methods:

• Developed a new three-body method combining Faddeev hyperspherical harmonics and the R-matrix method.
• Obtained a full solution for the three-body alpha+alpha+alpha continuum.
• Specifically addressed long-range effects from pairwise Coulomb interactions.

Main Results:

• The new triple-alpha reaction rate agrees with existing compilations for temperatures above 0.07 GK.
• A significant enhancement (≈10^12) of the reaction rate was found at lower temperatures (0.02 GK).
• The updated rate does not substantially alter the evolution of one-solar-mass stars, including their red-giant phase and white dwarf remnants.

Conclusions:

• The novel three-body method provides a more accurate triple-alpha reaction rate, especially at low temperatures.
• Despite the low-temperature enhancement, the overall evolution of Sun-like stars remains consistent with observations.
• The study validates current understanding of red-giant phases and white dwarf formation in solar-mass stars.