The Effects of Changes in Reaction Rates on Simulations of Nova Explosions

TL;DR

This paper investigates how variations in nuclear reaction rates influence nova explosion models and their role in enriching the galaxy with heavy elements, emphasizing the importance of including specific reactions like the pep reaction.

Contribution

It provides new insights into the impact of reaction rate changes on nova outburst properties and highlights the need to incorporate the pep reaction in nova simulations.

Findings

Reaction rate variations significantly alter nova outburst predictions.

Including the pep reaction affects the modeling of thermonuclear runaways.

Novae contribute substantially to galactic isotopic abundances.

Abstract

Classical novae participate in the cycle of Galactic chemical evolution in which grains and metal enriched gas in their ejecta, supplementing those of supernovae, AGB stars, and Wolf-Rayet stars, are a source of heavy elements for the ISM. Once in the diffuse gas, this material is mixed with the existing gases and then incorporated into young stars and planetary systems during star formation. Infrared observations have confirmed the presence of carbon, SiC, hydrocarbons, and oxygen-rich silicate grains in nova ejecta, suggesting that some fraction of the pre-solar grains identified in meteoritic material come from novae. The mean mass returned by a nova outburst to the ISM probably exceeds ~2 x 10^{-4} Solar Masses. Using the observed nova rate of 35 per year in our Galaxy, it follows that novae introduce more than ~7 x 10^{-3} Solar Masses per year of processed matter into the ISM. Novae are expected to be the major source of 15N and 17O in the Galaxy and to contribute to the abundances of other isotopes in this atomic mass range. Here, we report on how changes in the nuclear reaction rates affect the properties of the outburst and alter the predictions of the contributions of novae to Galactic chemical evolution. We also discuss the necessity of including the pep reaction in studies of thermonuclear runaways in material accreted onto white dwarfs.