2MASS photometry and age estimate of globular clusters in the outer halo of M31

Abstract

We present the first photometric results in J, H, and K_s from 2MASS imaging of 10 classical globular clusters in the far outer regions of M31. Combined with the V and I photometric data from previous literature, we constructed the color-color diagram between J-K_s and V-I. By comparing the integrated photometric measurements with evolutionary models, we estimate the ages of these clusters. The results showed that, all of these clusters are older than $3\times 10^9$ yrs, of which 4 are older than 10 Gyrs and the other 6 are in intermediate ages between 3-8 Gyrs. The masses for these outer halo GCs are from $7.0\times 10^4{M}_{s}un$ to $1.02\times 10^6{M}_{s}un$. We argued that, GC2 and GC3, the ages, metallicities and the distance moduli of which are nearly the same, were accreted from the same satellite galaxy, if they did not form {\it in situ}. The statistical results show that, ages and metallicities for these 10 M31 outer halo GCs do not vary with projected radial position, and the relationship between age and metallicity doest not exit.

Accepted for Publication in RAA, 14 pages, 8 figures and 3 tables

References in corpus (13)

• The ACS Survey of Galactic Globular Clusters. I. Overview and Clusters Without Previous HST Photometry
• Evidence for an accretion origin for the outer halo globular cluster system of M31
• An updated survey of globular clusters in M31. II Newly discovered bright and remote clusters
• ACS photometry of extended, luminous globular clusters in the outskirts of M31
• Globular clusters in the outer halo of M31: the survey
• Reddening, Colour and Metallicity of the M31 Globular Cluster System
• ACS photometry of newly-discovered globular clusters in the outer halo of M31
• Spectral Energy Distributions and Age Estimates of 39 Globular Clusters in M31
• A "super" star cluster grown old: the most massive star cluster in the Local Group
• New age estimates of M31 globular clusters from multi-colour photometry
• Determination of fundamental properties of an M31 globular cluster from main-sequence photometry
• Age and mass constraints for a young massive cluster in M31 based on spectral-energy-distribution fitting
• Detailed study of B037 based on {\sl HST} images

Cited by in corpus (4)

• The outer halo globular cluster system of M31 - I. The final PAndAS catalogue
• The LAMOST spectroscopic survey of star clusters in M31. II. Metallicities, ages and masses
• The Role of Dust in Models of Population Synthesis
• Modeling and analysis of medium-resolution integrated-light spectra of globular clusters in dwarf galaxies