Full spectral fitting of Milky Way and M 31 globular clusters: ages and metallicities

Cezario, E.; Coelho, P.; Alves-Brito, Alan; Forbes, Duncan A.; Brodie, Jean P.

doi:10.1051/0004-6361/201220336

Cited by 33 publications

(46 citation statements)

References 81 publications

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“…The other two clusters, B347-G154 and B083-G146, should be old clusters according to their red colours. In the third panel of the figure we compare our results with those from Chen et al (2016) and Cezario et al (2013), who use the full spectral fitting method. The ages of the young clusters from Chen et al (2016) are also estimated from the SED fittings.…”

Section: Resultsmentioning

confidence: 87%

“…Ma et al (2012) determined the age and mass of B514 by comparing its spectral energy distribution (SED) with theoretical stellar population synthesis models. Cezario et al (2013) obtained ages and metallicities of 38 M31 and 41 Galactic GCs by comparing their observed integrated spectra with the SSP model spectra on a pixelby-pixel basis. Fan et al (2016) derived ages and metallicities of 22 confirmed M31 GCs and concluded that using a combination of spectroscopic and photometric data resulted more reliable parameters than those from either spectroscopic data only or photometric data only.…”

Section: Introductionmentioning

confidence: 99%

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Estimating ages and metallicities of M31 star clusters from LAMOST DR6

Wang

Chen

2021

A&A

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Context. Determining the metallicities and ages of M31 clusters is fundamental to the study of the formation and evolution of M31 itself. The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) has carried out a systematic spectroscopic campaign of clusters and candidates in M31. Aims. We constructed a catalogue of 346 M31 clusters observed by LAMOST. By combining the information of the LAMOST spectra and the multi-band photometry, we developed a new algorithm to estimate the metallicities and ages of these clusters. Methods. We distinguish young clusters from old using random forest classifiers based on a empirical training data set selected from the literature. Ages of young clusters are derived from the spectral energy distribution (SED) fits of their multi-band photometric measurements. Their metallicities are estimated by fitting their observed spectral principal components extracted from the LAMOST spectra with those from the young metal-rich single stellar population (SSP) models. For old clusters we built non-parameter random forest models between the spectral principal components and/or multi-band colours and the parameters of the clusters based on a training data set constructed from the SSP models. The ages and metallicities of the old clusters are then estimated by fitting their observed spectral principal components extracted from the LAMOST spectra and multi-band colours from the photometric measurements with the resultant random forest models. Results. We derived parameters of 53 young and 293 old clusters in our catalogue. Our resultant parameters are in good agreement with those from the literature. The ages of ∼ 30 catalogued clusters and metallicities of ∼ 40 sources are derived for the first time.

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Section: Resultsmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Estimating ages and metallicities of M31 star clusters from LAMOST DR6

Wang

Chen

2021

A&A

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“…Studies of GCs have shown a variety of AMRs in the past, e.g., the Milky Way (Salaris & Weiss 2002;Mendel et al 2007;Leaman et al 2013;VandenBerg et al 2013;Roediger et al 2014), M31 (Jiang et al 2003;Fan et al 2006;Cezario et al 2013), the Large Magellanic Cloud (Carrera et al 2011), and NGC147, NGC185, and NGC205 (Sharina et al 2006). The AMRs found by these studies all share an anti-correlation between age and metallicity, which is expected, as the metallicity of GCs reflects the metallicity of the environment in which they have formed.…”

Section: Amr and The M/l Ratios Of Gcsmentioning

confidence: 99%

“…We take the age and metallicity data of a sample of 38 GCs in M31 from Cezario et al (2013) that has been obtained by using a spectral fitting technique to the observed integrated . The SSP curves in this plot do not include the effect of dynamical evolution.…”

Section: Amr and The M/l Ratios Of Gcsmentioning

confidence: 99%

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A Possible Solution for the M/L–[Fe/H] Relation of Globular Clusters in M31. II. The Age–Metallicity Relation

Haghi¹,

Khalaj²,

Zonoozi³

et al. 2017

ApJ

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This is the second paper in a series in which we present a new solution to reconcile the prediction of single stellar population (SSP) models with the observed stellar mass-to-light (M/L) ratios of globular clusters (GCs) in M31 and their trend with respect to [ ] Fe H . In the present work, our focus is on the empirical relation between age and metallicity for GCs and its effect on the M/L ratio. Assuming that there is an anti-correlation between the age of M31 GCs and their metallicity, we evolve dynamical SSP models of GCs to establish a relation between the M/L ratio (in the V and K band) and metallicity. We then demonstrate that the established M/L-[Fe/H] relation is in perfect agreement with that of M31 GCs. In our models, we consider both the canonical initial mass function (IMF) and the top-heavy IMF, depending on cluster birth density and metallicity as derived independently from Galactic GCs and ultra-compact dwarf galaxies by Marks et al. Our results signify that the combination of the density-and metallicity-dependent top-heavy IMF, the anti-correlation between age and metallicity, stellar evolution, and standard dynamical evolution yields the best possible agreement with the observed trend of M/L-[Fe/H] for M31 GCs.

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Spectroscopic and dynamic orbital analyses of metal‐poor and high proper‐motion stars: I. HD 8724 and HD 195633

Marışmak,

Şahin,

Güney

et al. 2024

Astron Nachr

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In this study, spectral, age, kinematic, and orbital dynamical analyses were conducted on metal‐poor and high proper‐motion (HPM) stars, HD 8724 and HD 195633, selected from the Solar neighborhood. This analysis combines detailed abundance measurements, kinematics, and orbital dynamics to determine their origin. Standard 1D local thermodynamic equilibrium analysis provides a fresh determination of the atmospheric parameters: Teff = 4700 ± 115 K, log g = 1.65 ± 0.32 cgs, [Fe/H] = −1.59 ± 0.04 dex, and a microturbulent velocity 1.58 ± 0.50 km s−1 for HD 8724 and Teff = 6100 ± 205 K, log g = 3.95 ± 0.35 cgs, [Fe/H] = −0.52 ± 0.05 dex, and 1.26 ± 0.50 km s−1 for HD 195633. The ages were estimated using a Bayesian approach (12.25 Gyr for HD 8724 and 8.15 Gyr for HD 195633). The escape scenarios of these stars from 170 candidate globular clusters (GCs) in the Galaxy were also investigated because of their chemical and physical differences (HPM and metal‐poor nature). Accordingly, the calculated probability of encounter (59%) for HD 8724 at a distance of five tidal radius suggests that star HD 8724 may have escaped from NGC 5139 ( Cen), supported by its highly flattened orbit and may belong to a subpopulation of this GC. Conversely, HD 195633's kinematics, age, and metal abundances point toward an escape from the bulge GC NGC 6356.

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Full spectral fitting of Milky Way and M 31 globular clusters: ages and metallicities

Cited by 33 publications

References 81 publications

Estimating ages and metallicities of M31 star clusters from LAMOST DR6

Estimating ages and metallicities of M31 star clusters from LAMOST DR6

A Possible Solution for the M/L–[Fe/H] Relation of Globular Clusters in M31. II. The Age–Metallicity Relation

Spectroscopic and dynamic orbital analyses of metal‐poor and high proper‐motion stars: I. HD 8724 and HD 195633

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