DDO Photometry of M71: Carbon and Nitrogen Patterns Among Evolving Giants

Abstract

We present V, B-V, and DDO C(41-42) and C(42-45) photometry for a sample of 75 red giants down to M_V = +2 in the relatively metal-rich Galactic globular cluster M71. The C(41-42) colors reveal a bimodal distribution of CN band strengths generally anticorrelated with CH band strength as measured by the C(42-45) color. Both DDO colors agree well with those found in 47 Tucanae -- a nearby globular cluster of similar metallicity -- and suggest nearly identical C and N abundance patterns among the giants of both clusters. A comparison with synthetic DDO colors demonstrates that little change in surface C or N abundance is required to match the colors of the M71 giants over the entire luminosity range observed. Apparently like 47 Tuc (a cluster of much greater mass and central concentration), M71 exhibits an abundance pattern which cannot be solely the result of internal mixing.

To appear in the Astronomical Journal, November 2001. 17 Pages, 5 Figures

References in corpus (2)

• Predictions for self-pollution in globular cluster stars
• Calibration of the CH and CN Variations Among Main Sequence Stars in M71 and in M13

Cited by in corpus (14)

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• C and N Abundances in Stars At the Base of the Red Giant Branch in M5
• On the C and N Abundances of 47 Tucanae Main Sequence Stars
• C and N Abundances in Stars At the Base of the Red Giant Branch in M15
• The Chemical Inhomogeneity of Faint M13 Stars: C and N Abundances
• Carbon abundances and 12C/13C from globular cluster giants
• Light-Element Abundances of Giant Stars in the Globular Cluster M71 (NGC 6838)
• Empirical estimates of the Na-O anti-correlation in 95 Galactic globular clusters
• The chemical composition of red giants in 47 Tucanae. II. Magnesium isotopes and pollution scenarios
• The RR Lyrae Star Period - K-band Luminosity Relation of the Globular Cluster M3
• Identifying Multiple Populations in M71 Using CN
• Abundance variations in the globular cluster M71 (NGC 6838)