A Comparison of the Chemical Composition of Main-sequence and Giant Stars in the Open Cluster NCC 752

• Published in: The Astrophysical journal Vol. 878; no. 2; pp. 99 - 119
• Main Authors: Lum, Michael G., Boesgaard, Ann Merchant
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 20.06.2019; IOP Publishing
• Subjects: Abundance; Aluminum; astronomical databases: miscellaneous; Astrophysics; Automatic pilots; Chemical composition; Chemical evolution; Giant stars; Heavy elements; Magnesium; Main sequence stars; nuclear reactions, nucleosynthesis, abundances; Open clusters; open clusters and associations: individual (NGC 752); Organic chemistry; Stars; stars: abundances; stars: evolution; Stellar evolution
• ISSN: 0004-637X; 1538-4357; 1538-4357
• DOI: 10.3847/1538-4357/ab1c4d

The chemical composition of stars in open clusters provides the best information on the chemical evolution of stars via comparison of main-sequence stars with 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 six giants. The mean cluster abundance of Fe is solar with [Fe/H] = −0.01 0.06 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.