Novae: An Important Source of Lithium in the Galaxy

TL;DR

This study uses advanced stellar simulations to show that novae are a major source of lithium in the galaxy, significantly improving previous abundance predictions and aligning with observations.

Contribution

The paper introduces a new model incorporating element diffusion and increased 3He to better predict lithium production in novae, aligning theory with observations.

Findings

Novae produce about 73% of galactic lithium.

Approximately 110 million lithium units are ejected by novae.

Novae occur roughly every 130 years in the galaxy.

Abstract

The source of the Galactic Lithium (Li) has long been a puzzle. With the discovery of Li in novae, extensive research has been conducted. However, there still exists a significant disparity between the observed abundance of lithium in novae and the existing theoretical predictions. Using the Modules for Experiments in Stellar Astrophysics (MESA), we simulate the evolution of nova with element diffusion and appropriately increased the amount of 3^He in the mixtures. Element diffusion enhances the transport efficiency between the nuclear reaction zone and the convective region on the surface of the white dwarf during nova eruptions, which results in more 7^Be to be transmitted to the white dwarf surface and ultimately ejected. Compared to the previous predictions, the abundance of 7^Be in novae simulated in our model significantly increases. And the result is able to explain almost all observed novae. Using the method of population synthesis, we calculate Li yield in the Galaxy. We find that the Galactic occurrence rate of nova is about 130 yr^{-1}, and about 110M Li produced by nova eruption is ejected into the interstellar medium (ISM). About 73\% of Li in the Galactic ISM originates from novae, and approximately 15\%-20\% of the entire Galaxy. It means that novae are the important source of Li in the Galactic.