Some Systematics of Galactic Globular Clusters

Abstract

The global properties of all known Galactic globular clusters are examined. The relationship between the luminosities and the metallicities of Galactic globular clusters is found to be complex. Among luminous clusters there is a correlation in the sense that the oldest clusters are slightly more metal deficient than are younger clusters. However, no such clear-cut relationship is found among the faintest globular clusters. The central concentration index C of globular clusters is seen to be independent of metallicity. The dependence of the half-light radii of globular clusters on their Galactocentric distances can be approximated by the relation $R_h\alpha R_{gc}^{2/3}$. Clusters with collapsed cores are mostly situated close to the Galactic nucleus. For $R_{gc}<10$ kpc the luminosities and the radii of clusters appear to be uncorrelated. The Galaxy differs from the LMC and the SMC in that it appears to lack highly flattened luminous clusters. Galactic globular clusters with ages $\ge$ 13.0 Gyr are all of Oosterhoff type II, whereas almost all of those with ages $<$ 13.0 Gyr have been assigned to Oosterhoff type I. Globular clusters with ages $<$11.5 Gyr are all located in the outer Galactic halo, have below-average luminosities and above-average radii. On the other hand the very old globular cluster NGC 6522 is situated close to the Galactic nucleus.

PASP, in press

References in corpus (3)

• The life cycle of star cluster in a tidal field
• RR Lyrae Stars, Metal-Poor Stars, and the Galaxy
• A New Look at the Old Star Cluster NGC 6791

Cited by in corpus (16)

• The Ages of 55 Globular Clusters as Determined Using an Improved delta V_TO^HB Method Along with Color-Magnitude Diagram Constraints, and Their Implications for Broader Issues
• Star count density profiles and structural parameters of 26 Galactic globular clusters
• Globular cluster number density profiles using Gaia DR2
• A new Milky Way halo star cluster in the Southern Galactic Sky
• Unmixing the Galactic Halo with RR Lyrae tagging
• Multiple stellar populations and their evolution in globular clusters: A nucleosynthesis perspective
• Constraints on the distance moduli, helium and metal abundances, and ages of globular clusters from their RR Lyrae and non-variable horizontal-branch stars. II. Multiple stellar populations in 47Tuc, M3, and M13
• The accretion history of the Milky Way. I. How it shapes globular clusters and dwarf galaxies
• The STREGA survey. II. Globular Cluster Palomar 12
• An analysis of the most distant catalogued open clusters -- Re-assessing fundamental parameters with Gaia EDR3 and $\text{ASteCA}$
• Dynamical evolution of Milky Way globular clusters on the cosmological timescale I. Mass loss and interaction with the nuclear star cluster
• Metallicity field and selection effects in spatial distribution of the Galactic globular cluster system
• Variable stars in the globular cluster M28 (NGC 6626)
• Sizes of Galactic Globular Clusters
• Model for common growth of supermassive black holes, bulges and globular star clusters: ripping off Jeans clusters
• Statistical analysis of Galactic globular cluster type properties