Metallicity estimates for old star clusters in M 33

Ma, Jun; Zhou, Xu; Chen, Jiansheng

doi:10.1051/0004-6361:20031556

Cited by 18 publications

(14 citation statements)

References 45 publications

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“…Chandar et al (2002) also estimated the ages of these clusters by comparing their integrated photometry with the SSP model in the color-color diagram. Ma et al (2004) showed that the ages estimated by Ma et al (2002) are in good agreement with those estimated by Chandar et al (2002;see Table 1 of Ma et al 2004 for details). Park et al (2009) estimated the ages and metallicities of 100 star clusters in M33, including four sample star clusters, by fitting the theoretical isochrones to the observational colormagnitude diagrams.…”

Section: Halo Gc Sample In M33supporting

confidence: 56%

“…In general, the ages obtained by Park et al (2009) are younger than those in Chandar et al (2002) and Ma et al (2002). Some works determined the metallicities of the sample star clusters (Cohen et al 1984;Christian & Schommer 1988;Brodie & Huchra 1991;Sarajedini et al 1998Sarajedini et al , 2000Ma et al 2004). Using two reddening-independent techniques, Cohen et al (1984) determined the metallicities of four sample clusters.…”

Section: Halo Gc Sample In M33mentioning

confidence: 98%

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Structural Parameters for 10 Halo Globular Clusters in M33

2015

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In this paper, we present the properties of 10 halo globular clusters (GCs) with luminosities L ; 5-7 × 10 5 L e in the Local Group galaxy M33 using images from the Hubble Space Telescope WFPC2 in the F555W and F814W bands. We obtained the ellipticities, position angles, and surface brightness profiles for each GC. In general, the ellipticities of the M33 sample clusters are similar to those of the M31 clusters. The structural and dynamical parameters are derived by fitting the profiles to three different models combined with mass-to-light ratios (M/L values) from population-synthesis models. The structural parameters include core radii, concentration, half-light radii, and central surface brightness. The dynamical parameters include the integrated cluster mass, integrated binding energy, central surface mass density, and predicted line of sight velocity dispersion at the cluster center. The velocity dispersions of the four clusters predicted here agree well with the observed dispersions by Larsen et al. The results here showed that the majority of the sample halo GCs are better fitted by both the King model and the Wilson model than the Sérsic model. In general, the properties of the clusters in M33, M31, and the Milky Way fall in the same regions of parameter spaces. The tight correlations of cluster properties indicate a "fundamental plane" for clusters, which reflects some universal physical conditions and processes operating at the epoch of cluster formation.

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Section: Halo Gc Sample In M33supporting

confidence: 56%

Section: Halo Gc Sample In M33mentioning

confidence: 98%

Structural Parameters for 10 Halo Globular Clusters in M33

2015

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“…Ferguson et al (2007) identified a break in the surface brightness profile of M33 at ∼8 kpc that nicely corresponds with the change in the slope of the AGB gradient, suggesting the existence of two components. The analysis of stellar clusters (Sarajedini et al 2000, Ma et al 2004) and RR Lyrae stars ) support this scenario. Some clusters de-project onto the inner disc gradient while others do agree, within the errors, with an outer disc/halo metallicity.…”

Section: M33mentioning

confidence: 72%

The metallicity gradient as a tracer of history and structure: the Magellanic Clouds and M33 galaxies

Cioni¹

2009

A&A

134

154

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Context. The stellar metallicity and its gradient place constraints on the formation and evolution of galaxies. Aims. This is a study of the metallicity gradient of the LMC, SMC and M33 galaxies derived from their asymptotic giant branch (AGB) stars. Methods. The [Fe/H] abundance was derived from the ratio between C-and M-type AGB stars and its variation analysed as a function of galactocentric distance. Galaxy structure parameters were adopted from the literature.Results. The metallicity of the LMC decreases linearly as −0.047± 0.003 dex kpc −1 out to ∼8 kpc from the centre. In the SMC, [Fe/H] has a constant value of ∼−1.25 ± 0.01 dex up to ∼12 kpc. The gradient of the M33 disc, until ∼9 kpc, is −0.078 ± 0.003 dex kpc −1 while the outer disc/halo, out to ∼25 kpc, has [Fe/H] ∼ −1.7 dex. Conclusions. The metallicity of the LMC, as traced by different populations, bears the signature of two major star forming episodes: the first one constituting a thick disc/halo population and the second one a thin disc and bar due to a close encounter with the Milky Way and SMC. The [Fe/H] of the recent episode supports an LMC origin for the Stream. The metallicity of the SMC supports star formation, ∼3 Gyr ago, as triggered by LMC interaction and sustained by the bar in the outer region of the galaxy. The SMC [Fe/H] agrees with the present-day abundance in the Bridge and shows no significant gradient. The metallicity of M33 supports an "insideout" disc formation via accretion of metal poor gas from the interstellar medium.

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“…For MKKSS12, we find log 10 (t/yr) = 10.0 and log 10 (M/M ) = 5.65 while San Roman et al (2009) give log 10 (t/yr) = 8.6 and log 10 (M/M ) = 4.54. Chandar et al (2002) give log 10 (t/yr) = 9.4 using SSP models, and Ma et al (2004) give log 10 (t/yr) = 9.63 and log 10 (M/M ) = 5.47 using their BATC spectrophotometric system composed of 13 narrow passbands, also compared to SSP models. For young clusters, the age given by San Roman et al (2009) is often older than in our values.…”

Section: Derived Physical Parameters Of Clustersmentioning

confidence: 99%

Deriving physical parameters of unresolved star clusters

Meulenaer

Narbutis

Mineikis

et al. 2015

A&A

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Context. When trying to derive the star cluster physical parameters of the M 33 galaxy using broad-band unresolved ground-based photometry, previous studies mainly made use of simple stellar population models, shown in the recent years to be oversimplified. Aims. In this study, we aim to derive the star cluster physical parameters (age, mass, and extinction; metallicity is assumed to be LMC-like for clusters with age below 1 Gyr and left free for older clusters) of this galaxy using models that take stochastic dispersion of cluster integrated colors into account. Methods. We use three recently published M 33 catalogs of cluster optical broad-band photometry in standard UBVRI and in CFHT/MegaCam u * g r i z photometric systems. We also use near-infrared JHK photometry that we derive from deep 2MASS images. We derive the cluster parameters using a method that takes into account the stochasticity problem, presented in previous papers of this series. Results. The derived differential age distribution of the M 33 cluster population is composed of a two-slope profile indicating that the number of clusters decreases when age gets older. The first slope is interpreted as the evolutionary fading phase of the cluster magnitudes, and the second slope as the cluster disruption. The threshold between these two phases occurs at ∼300 Myr, comparable to what is observed in the M 31 galaxy. We also model by use of artificial clusters the ability of the cluster physical parameter derivation method to correctly derive the two-slope profile for different photometric systems tested.

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Metallicity estimates for old star clusters in M 33

Cited by 18 publications

References 45 publications

Structural Parameters for 10 Halo Globular Clusters in M33

Structural Parameters for 10 Halo Globular Clusters in M33

The metallicity gradient as a tracer of history and structure: the Magellanic Clouds and M33 galaxies

Deriving physical parameters of unresolved star clusters

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