# A Comparison of the Chemical Composition of Main Sequence and Giant Stars in the Open Cluster NCC 752

## TL;DR

This study compares the chemical compositions of main sequence and giant stars in open cluster NGC 752, revealing minimal abundance differences and evidence of stellar processing, while also testing automated abundance analysis methods.

## Contribution

It provides the first detailed abundance comparison between dwarfs and giants in NGC 752 and introduces a pilot program for automated stellar abundance determination.

## Key findings

- Cluster Fe abundance is solar with no difference between dwarfs and giants.
- Evidence of CNO processing and Na enhancement in giants.
- No s-process enhancement observed in giants.

## Abstract

The chemical composition of stars in open clusters provides the best information on the chemical evolution of stars via comparison of the main sequence stars with the evolved giants. This is a case study of the abundances in the dwarfs and giants in the old, open cluster, NGC 752. It is also a pilot program for automated abundance determinations, including equivalent width measurements, stellar parameter determinations, and abundance analysis. We have found abundances of 31 element-ion combinations in 23 dwarfs and 6 giants. The mean cluster abundance of Fe is solar with [Fe/H]$=-0.01\pm0.06$ with no significant difference between the dwarfs and giants. We find that the cluster abundances of other elements, including alpha-elements, to be at, or slightly above solar levels. We find some evidence for CNO processing in the spectra of the giants. The enhancement of Na in giants indicates that the NeNa cycle has occurred. The abundances of Mg and Al are similar in the dwarfs and giants indicating that the hotter MgAl cycle has not occurred. We find no evidence of s-process enhancements in the abundances of heavy elements in the giants.