Variations in the Na-O anticorrelation in globular clusters: Evidence for a deep mixing episode in red giant branch stars

Abstract

The Na-O anticorrelation seen in almost all globular clusters ever studied using high-resolution spectroscopy is now generally explained by the primordial pollution from the first generation of the intermediate-mass asymptotic giant branch stars to the proto-stellar clouds of the second generation of stars. However, the primordial pollution scenario may not tell the whole story for the observed Na-O anticorrelations in globular clusters. Using the recent data by Carretta and his collaborators, the different shapes of the Na-O anticorrelations for red giant branch stars brighter than and fainter than the red giant branch bump can be clearly seen. If the elemental abundance measurements by Carretta and his collaborators are not greatly in error, this variation in the Na-O anticorrelation against luminosity indicates an internal deep mixing episode during the ascent of the low-mass red giant branch in globular clusters. Our result implies that the multiple stellar population division scheme solely based on [O/Fe] and [Na/Fe] ratios of a globular cluster, which is becoming popular, is not reliable for stars brighter than the red giant branch bump. Our result also suggests that sodium supplied by the deep mixing may alleviate the sodium under-production problem within the primordial asymptotic giant branch pollution scenario.

Accepted for publication in MNRAS. 5 pages, 4 figures and 2 tables.

References in corpus (7)

• Na-O Anticorrelation and HB. VII. The chemical composition of first and second-generation stars in 15 globular clusters from GIRAFFE spectra
• Origin of the abundance patterns in Galactic globular clusters: constraints on dynamical and chemical properties of globular clusters
• Enrichment by supernovae in globular clusters with multiple populations
• Na-O Anticorrelation and HB. II. The Na-O anticorrelation in the globular cluster NGC 6752
• The self-enrichment scenario in intermediate metallicity globular clusters
• Na-O Anticorrelation and HB. IV. Detection of He-rich and He-poor stellar populations in the globular cluster NGC 6218
• Angular Diameters and Effective Temperatures of Twenty-five K Giant Stars from the CHARA Array

Cited by in corpus (26)

• Chemical Abundances for 855 Giants in the Globular Cluster Omega Centauri (NGC 5139)
• Abundances for a large sample of red giants in NGC 1851: hints for a merger of two clusters?
• X-shooter observations of main sequence stars in the globular cluster NGC 2808: first chemical tagging of a He-normal and a He-rich dwarf
• A Non-radial Oscillation Mode in an Accreting Millisecond Pulsar?
• Multiple Stellar Populations of Globular Clusters from Homogenous Ca by Photometry I. M22 (NGC 6656)
• Excitation of a nonradial mode in a millisecond X-ray pulsar XTE J1751-305
• Multiple stellar populations of globular clusters from homogeneous Ca-Cn photometry. II. M5 (NGC 5904) and a new filter system
• Low-resolution Spectroscopy for the Globular Clusters with Signs of Supernova Enrichment: M22, NGC 1851 and NGC 288
• On the metallicity distribution of the peculiar globular cluster M22
• Mass loss of different stellar populations in Globular Clusters: the case of M4
• First inverse kinematics study of the ${}^{22}$Ne$(p,\gamma {)}^{23}$Na reaction and its role in AGB star and classical nova nucleosynthesis
• Multiple stellar populations of globular clusters from homogeneous Ca--CN photometry. III. NGC 6752
• Multiple stellar populations of globular clusters from homogeneous Ca--CN photometry. IV. Toward precision populational tagging
• Investigating multi-frequency pulse profiles of PSRs B0329+54 and B1642-03 in an inverse Compton scattering (ICS) model
• Magnetic Pair Creation Transparency in Gamma-Ray Pulsars
• Multiple Stellar Populations of Globular Clusters From Homogeneous Ca-CN-CH-NH Photometry. VII. Metal-Poor Populations in 47 Tucanae (NGC 104)
• Stellar populations in star clusters
• Multiple Stellar Populations of Globular Clusters from Homogeneous Ca--CN--CH Photometry. V. $c{n}_{\mathrm{JWL}}^{\prime }$ as a Surrogate $c{n}_{\mathrm{JWL}}$ Index and NGC 6723
• First inverse kinematics measurement of key resonances in the ${}^{22}\text{Ne}(p,\gamma {)}^{23}\text{Na}$ reaction at stellar temperatures
• Formation of Multiple Populations of M5 (NGC 5904)
• A high-resolution spectroscopic study of two new Na- and Al-rich field giants -- likely globular cluster escapees in the Galactic halo
• Non-axisymmetric magnetic modes of neutron stars with purely poloidal magnetic fields
• Light curves from rapidly rotating neutron stars
• Frequency resolved radio and high-energy emission of pulsars
• Searching for resonance states in ${}^{22}$Ne($p,\gamma$)${}^{23}$Na
• Axisymmetric magnetic modes of neutron stars having mixed poloidal and toroidal magnetic fields