The Kinematics and Metallicity of the M31 Globular Cluster System

Perrett, K.; Bridges, Terry J.; Hanes, David A.; Irwin, M. J.; Brodie, Jean P.; Carter, D.; Huchra, J. P.; Watson, Fred

doi:10.1086/340186

Cited by 155 publications

(431 citation statements)

References 51 publications

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“…By convention, the metal-poor GCs are often called the blue sequence while the metal-richer ones are the red sequence. The translation from GC colour to metallicity (which is monotonic, but may be nonlinear) is ultimately established from spectroscopic abundance measurements, which have now been done in several galaxies (see the work by Brodie & Huchra 1990;Cohen et al 1998Cohen et al , 2003Kissler-Patig et al 1998;Barmby et al 2000;Perrett et al 2002;Puzia et al 2005;Cenarro et al 2007;Strader et al 2007;Woodley et al 2010; and the fundamental data for the Milky Way clusters).…”

Section: Metallicity Distributionsmentioning

confidence: 99%

Massive star clusters in galaxies

Harris

2010

Phil. Trans. R. Soc. A.

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The ensemble of all star clusters in a galaxy constitutes its star cluster system. In this review, the focus of the discussion is on the ability of star clusters, particularly the systems of old massive globular clusters (GCs), to mark the early evolutionary history of galaxies. I review current themes and key findings in GC research, and highlight some of the outstanding questions that are emerging from recent work.

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Section: Metallicity Distributionsmentioning

confidence: 99%

Massive star clusters in galaxies

Harris

2010

Phil. Trans. R. Soc. A.

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“…Similar to the Milky Way, M 31 appears to have at least two GC subpopulations, a metal-rich, spatially concentrated subpopulation of GCs and a more metal-poor, spatially extended GC subpopulation (Huchra et al 1991;Barmby et al 2000). Also, again similar to the Milky Way GCs, the metal-rich GCs in M 31 rotate and show "bulge-like" kinematics (Perrett et al 2002). However, unlike the case in the Milky Way, the metal-poor GCs also show significant rotation (Huchra et al 1991;Perrett et al 2002;Lee et al 2008).…”

Section: Introductionmentioning

confidence: 99%

An HST/WFPC2 survey of bright young clusters in M 31

Perina

Cohen²,

Barmby

et al. 2010

A&A

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Aims. We present the main results of an imaging survey of possible young massive clusters (YMC) in M 31 performed with the Wide Field and Planetary Camera 2 (WFPC2) on the Hubble Space Telescope (HST), with the aim of estimating their age and their mass. We obtained shallow (to B ∼ 25) photometry of individual stars in 19 clusters (of the 20 targets of the survey). We present the images and color magnitude diagrams (CMDs) of all of our targets. Methods. Point spread function fitting photometry of individual stars was obtained for all the WFPC2 images of the target clusters, and the completeness of the final samples was estimated using extensive sets of artificial stars experiments. The reddening, age, and metallicity of the clusters were estimated by comparing the observed CMDs and luminosity functions (LFs) with theoretical models. Stellar masses were estimated by comparison with theoretical models in the log(Age) vs. absolute integrated magnitude plane, using ages estimated from our CMDs and integrated J, H, K magnitudes from 2MASS-6X. Results. Nineteen of the twenty surveyed candidates were confirmed to be real star clusters, while one turned out to be a bright star. Three of the clusters were found not to be good YMC candidates from newly available integrated spectroscopy and were in fact found to be old from their CMD. Of the remaining sixteen clusters, fourteen have ages between 25 Myr and 280 Myr, two have older ages than 500 Myr (lower limits). By including ten other YMC with HST photometry from the literature, we assembled a sample of 25 clusters younger than 1 Gyr, with mass ranging from 0.6 × 10 4 M to 6 × 10 4 M , with an average of ∼3 × 10 4 M . Our estimates of ages and masses well agree with recent independent studies based on integrated spectra. Conclusions. The clusters considered here are confirmed to have masses significantly higher than Galactic open clusters (OC) in the same age range. Our analysis indicates that YMCs are relatively common in all the largest star-forming galaxies of the Local Group, while the lack of known YMC older than 20 Myr in the Milky Way may stem from selection effects.

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“…Figure 7 shows the metallicities versus ages of the GCs. The metallicities are from the literature (Huchra et al, 1991;Barmby et al, 2000;Perrett et al, 2002;Galleti et al, 2009;Caldwell et al, 2011), Paper I as well as this work and the ages are from the Fan et al (2010), Paper I and this work. We would like to see if there is any relationship between the ages and metallicities for these GCs.…”

Section: Nomentioning

confidence: 99%

“…Figure 8 shows the metallicity distributions of the GCs and the HGCs, respectively. In the Left panel, the sample includes all the GCs which have spectroscopic metallicity from the literature (Huchra et al, 1991;Barmby et al, 2000;Perrett et al, 2002;Galleti et al, 2009;Caldwell et al, 2011) and Paper I as well as this work. In total, there are 386 GCs with spectroscopic metallicity in the distribution.…”

Section: Nomentioning

confidence: 99%

Spectroscopic study of globular clusters in the halo of M31 with the Xinglong 2.16 m telescope II: dynamics, metallicity and age

Zhang¹,

Huang²,

Li³

et al. 2012

Res. Astron. Astrophys.

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In our Paper I, we performed the spectroscopic observations of 11 confirmed GCs in M31 with the Xinglong 2.16m telescope and we mainly focus on the fits method and the metallicity gradient for the M31 GC sample. In this paper, we analyzed and discussed more about the dynamics, metallicity and age, and their distributions as well as the relationships between these parameters. In our work, eight more confirmed GCs in the halo of M31 were observed, most of which lack the spectroscopic information before. These star clusters are located far from the galactic center at a projected radius of ∼ 14 to ∼ 117 kpc, which are more spatially extended than that in the previous work. The Lick absorption-line indices and the radial velocities have been measured primarily. Then the ages, metallicities [Fe/H] and [α/Fe] have been fitted by comparing the observed spectral feature indices and the SSP model of Thomas et al. in the Cassisi and Padova stellar evolutionary tracks, respectively. Our results show that most of the star clusters of our sample are older than 10 Gyr except B290∼ 5.5 Gyr, and most of them are metal-poor with the metallicity [Fe/H] < −1, suggesting that these clusters were born at the early stage of the galaxy's formation. We find that the metallicity gradient for the outer halo clusters with r p > 25 kpc may not exist with a slope of −0.005 ± 0.005 dex kpc −1 and if the outliers G001 and H11 are excluded, the slope dose not change significantly with a value of −0.002 ± 0.003 dex kpc −1 . We also find that the metallicity is not a function of age for the GCs with age < 7 Gyr while for the old GCs with age > 7 Gyr there seems to be a trend that the older ones have lower metallicity. Besides, We plot metallicity distributions with the largest sample of M31 GCs so far and it shows the bimodality is not significant and the number of the metal-poor and metal-rich groups becomes comparable. The spatial distributions shows that the metal-rich group is more centrally concentrated while the metal-poor group is occupy a more extended halo and the young population is centrally concentrated while the old populaiton is more extended spatially to the outer halo.

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The Kinematics and Metallicity of the M31 Globular Cluster System

Cited by 155 publications

References 51 publications

Massive star clusters in galaxies

Massive star clusters in galaxies

An HST/WFPC2 survey of bright young clusters in M 31

Spectroscopic study of globular clusters in the halo of M31 with the Xinglong 2.16 m telescope II: dynamics, metallicity and age

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