An Analysis of the Red Giant Bump

Abstract

The red giant branch bump is a phenomenon that consists of a decrease in luminosity for a given time during the red giant branch phase. Discrepancies between models and observations show that it is not yet fully understood. It is therefore interesting to try to understand the influence of various parameters that are part of the structure of the star on the bump. We have used the stellar evolution code called Clés to study the influence of the total mass of the star, its overshooting and undershooting parameters, its metallicity, and the microscopic and turbulent diffusion. To study the effects of changing these parameters, the attention was given to the track of the star in the Hertzsprung-Russell diagram during its evolution and on the hydrogen abundance profile of the star, the discontinuity in the latter being the key element for the appearance of the bump. Effects can be seen on the bump for each of the parameters studied, which can be summarized in two categories: a change in the luminosity at which the bump occurs and a change in the size of the bump, thus the importance of the observed decrease in luminosity.