Possible Solution to the Triple Alpha Fine-Tuning Problem: Spallation Reactions during Planet Formation

Abstract

Carbon is produced during the helium burning phase of sufficiently massive stars through the triple alpha process. The $0^{+}$ energy level of the carbon nucleus allows for resonant nuclear reactions, which act to greatly increase the carbon yields compared to the non-resonant case. Many authors have argued that small changes to the energy level of this resonance would lead to a significantly lower carbon abundance in the universe, and this sensitivity is often considered an example of fine-tuning. By considering spallation reactions occuring during the process of planet formation, this paper presents a partial solution to this triple alpha fine-tuning problem. Young stellar objects generate substantial luminosities of particle radiation (cosmic rays) that can drive nuclear reactions through spallation. If the standard triple alpha process is inoperative, stars tend to synthesize oxygen (and other alpha elements) rather than carbon. Cosmic rays can interact with oxygen nuclei to produce carbon while planets are forming. The resulting carbon abundances are significant, but much smaller than those observed in our universe. However, for a range of conditions -- as delineated herein -- spallation reactions can result in carbon-to-oxygen ratios roughly comparable to those found on Earth and thereby obviate the triple alpha fine-tuning problem.

arXiv comment25 pages, 2 figures, accepted for publication in Astroparticle Physics

References in corpus (21)

• Interstellar Dust Grains
• The origins and concentrations of water, carbon, nitrogen and noble gases on Earth
• The Origin of T Tauri X-ray Emission: New Insights from the Chandra Orion Ultradeep Project
• Spitzer Space Telescope study of disks in the young $\sigma$ Orionis cluster
• Ab initio calculation of the Hoyle state
• Dimensionless constants, cosmology and other dark matters
• The Magnetic Fields of Classical T Tauri Stars
• Why the Universe is Just So
• Global X-ray properties of the Orion Nebula region
• Close-in planetesimal formation by pile-up of drifting pebbles
• Protostars: Forges of cosmic rays?
• Persistence of Flare-Driven Atmospheric Chemistry on Rocky Habitable Zone Worlds
• Life at the Interface of Particle Physics and String Theory
• Stellar production rates of carbon and its abundance in the universe
• Atmospheric effects of stellar cosmic rays on Earth-like exoplanets orbiting M-dwarfs
• A Critical Examination of the X-Wind Model for Chondrule and Calcium-rich, Aluminum-rich Inclusion Formation and Radionuclide Production
• Dependence of the triple-alpha process on the fundamental constants of nature
• The Degree of Fine-Tuning in our Universe -- and Others
• The Multiverse and Particle Physics
• Sensitivity of Carbon and Oxygen Yields to the Triple-Alpha Resonance in Massive Stars
• Stellar Helium Burning in Other Universes: A solution to the triple alpha fine-tuning problem