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

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.

26 pages, 9 figures, accepted for publication in ApJ

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• The OCCASO survey: Presentation and radial velocities of twelve Milky Way Open Clusters
• Some Stars are Totally Metal: A New Mechanism Driving Dust Across Star-Forming Clouds, and Consequences for Planets, Stars, and Galaxies
• Detailed chemical composition and orbit of the new globular cluster FSR1758: Implications for the accretion of the Sequoia dwarf galaxy onto the Milky Way
• NGC 6791: a probable bulge cluster without multiple populations
• Searching for chemical inhomogeneities in Open Clusters: Analysis of the CN and CH Molecular Band Strengths in NGC 2158, NGC 2420, NGC 2682, NGC 7789 and Berkeley 29
• OCCASO IV. Radial Velocities and Open Cluster Kinematics
• Updated properties of the old open cluster Melotte 66: Searching for multiple stellar populations