Reversed radial distribution trend of subpopulations in the globular clusters NGC 362 and NGC 6723

Abstract

Most globular clusters (GCs) are now known to host multiple stellar populations with different light element abundances. Here we use narrow-band photometry and low-resolution spectroscopy for NGC 362 and NGC 6723 to investigate their chemical properties and radial distributions of subpopulations. We confirm that NGC 362 and NGC 6723 are among the GCs with multiple populations showing bimodal CN distribution and CN-CH anti-correlation without a significant spread in calcium abundance. These two GCs show more centrally concentrated CN-weak earlier generation stars compared to the later generation CN-strong stars. These trends are reversed with respect to those found in previous studies for many other GCs. Our findings, therefore, seem contradictory to the current scenario for the formation of multiple stellar populations, but mass segregation acting on the two subpopulations might be a possible solution to explain this reversed radial trend.

12 pages, 8 figures, 2 tables, accepted for publication in ApJ

References in corpus (15)

• Fast rotating massive stars and the origin of the abundance patterns in galactic globular clusters
• Formation and Dynamical Evolution of Multiple Stellar Generations in Globular Clusters
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. I. Overview of the Project and Detection of Multiple Stellar Populations
• Spectroscopic and Photometric evidence of two stellar populations in the Galactic Globular Cluster NGC6121 (M4)
• Origin of the abundance patterns in Galactic globular clusters: constraints on dynamical and chemical properties of globular clusters
• Comparing CN and CH Line Strengths in a Homogeneous Spectroscopic Sample of 8 Galactic Globular Clusters
• First evidence of fully spatially mixed first and second generations in globular clusters: the case of NGC 6362
• Radial distributions of sub-populations in the globular cluster M15: a more centrally concentrated primordial population
• Probing the IGM/Galaxy Connection Toward PKS0405-123 III: The Galaxy Survey and Correlations with OVI Absorbers
• Multiple Stellar Populations of Globular Clusters from Homogenous Ca by Photometry I. M22 (NGC 6656)
• Low-resolution Spectroscopy for the Globular Clusters with Signs of Supernova Enrichment: M22, NGC 1851 and NGC 288
• Evolution of Binary Stars in Multiple-Population Globular Clusters
• The Na-O anticorrelation in horizontal branch stars. V. NGC 6723
• Multiple Populations in Globular Clusters and the Origin of the Oosterhoff Period Groups
• Light Element Chemistry and the Double Red Giant Branch in the Galactic Globular Cluster NGC 288

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• The dynamical origin of multiple populations in intermediate-age clusters in the Magellanic Clouds
• Chemical abundances in the metal-intermediate GC NGC 6723
• The radial distributions of the two main-sequence components in the young massive star cluster NGC 1856
• The CN-CH positive correlation in the globular cluster NGC 5286
• Peeking beneath the precision floor I: metallicity spreads and multiple elemental dispersions in the globular clusters NGC 288 and NGC 362
• New sub-grouping of multiple stellar populations in NGC 2808 based on low-resolution spectroscopy
• Structure of our Galactic Bulge from CN Measurements
• Re-examining the Radial Distributions of M13 Multiple Populations