Investigating the Consistency of Stellar Evolution Models with Globular Cluster Observations via the Red Giant Branch Bump

TL;DR

This study compares synthetic red giant branch bump magnitudes from the Dartmouth stellar evolution models with observational data from 72 globular clusters, assessing model accuracy across different metallicities.

Contribution

It evaluates the consistency of recent stellar evolution models with observed globular cluster data, highlighting areas of agreement and discrepancy.

Findings

Models agree with observations for [Fe/H] from 0 to -1.5.

Discrepancies appear at metallicities below -1.5.

Enhanced alpha-element models improve fit at certain metallicities.

Abstract

Synthetic RGBB magnitudes are generated with the most recent theoretical stellar evolution models computed with the Dartmouth Stellar Evolution Program (DSEP) code. They are compared to the observational work of Nataf et al., who present RGBB magnitudes for 72 globular clusters. A DSEP model using a chemical composition with enhanced $\alpha$ capture [$\alpha$/Fe] $ =+0.4$ and an age of 13 Gyr shows agreement with observations over metallicities ranging from [Fe/H] = $0$ to [Fe/H] $\approx-1.5$, with discrepancy emerging at lower metallicities.