Analysis of the CN and CH molecular band strengths in stars of the open cluster NGC 6791

TL;DR

This study uses low-resolution spectra to analyze CN and CH molecular band strengths across various stellar evolutionary stages in NGC 6791, revealing a significant CN spread but limited CH variation.

Contribution

It provides the first detailed analysis of CN and CH band variations in an open cluster using SDSS/SEGUE data, highlighting differences from globular cluster patterns.

Findings

Significant CN band strength spread observed.

No clear bimodality in CN bands like in globular clusters.

Limited variation in CH band strengths among stars.

Abstract

Low resolution SDSS/SEGUE spectra have been used to study the behavior of the strengths of the CN and CH molecular bands in stars at different evolutionary stages of the open cluster NGC 6791. We find a significant spread in the strengths of the CN bands, more than twice that expected from the uncertainties, although the bimodalities observed in globular clusters are not clearly observed here. This behavior, is observed not only among red clump objects but also in unevolved stars such as those in the main sequence and lower red giant branch. In contrast, not all the stars studied show significant scatter in their CH strengths.