A sequence of nitrogen-rich very red giants in the globular cluster NGC 1851

Abstract

We present the abundances of N in a sample of 62 stars on the red giant branch (RGB) in the peculiar globular cluster NGC 1851. The values of [N/Fe] ratio were obtained by comparing the flux measured in the observed spectra with that from synthetic spectra for up to about 15 features of CN. This is the first time that N abundances are obtained for such a large sample of RGB stars from medium-resolution spectroscopy in this cluster. With these abundances we provide a chemical tagging of the split red giant branch found from several studies in NGC 1851. The secondary, reddest sequence on the RGB is populated almost exclusively by N-rich stars, confirming our previous suggestion based on Stromgren magnitudes and colours. These giants are also, on average, enriched in s-process elements such as Ba, and are likely the results of pollution from low mass stars that experienced episodes of third dredge-up in the asymptotic giant branch phase.

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Cited by in corpus (8)

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• A broad perspective on multiple abundance populations in the globular cluster NGC 1851
• Light and Heavy Element Abundance Variations in the Outer Halo Globular Cluster NGC 6229
• A Nitrogen-Enhanced Metal-Poor star discovered in the globular cluster ESO280-SC06
• Metallicity of the globular cluster NGC 6388 from high resolution spectra of more than 160 giant stars
• Multiple Populations in NGC 1851: Abundance Variations and UV Photometric Synthesis in the Washington and HST/WFC3 Systems