<i>UBVI</i>CCD Photometry of the Old Open Cluster Berkeley 17

Krusberg, Zosia A. C.; Chaboyer, Brian

doi:10.1086/500258

Cited by 18 publications

(16 citation statements)

References 55 publications

(101 reference statements)

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“…6(a) we compare the value of [Fe/H] found with our method and the one from Schiavon et al (2005); the standard deviation between the two series of determinations is 0.17 dex. The reference ages are taken mainly from Salaris & Weiss 2002; Santos & Piatti 2004; Krusberg & Chaboyer 2006, for the clusters for which we did not find age reference we adopted values of 10 Gyr.…”

Section: Analysis Of Galactic Clustersmentioning

confidence: 99%

Spectroscopic ages and metallicities of stellar populations: validation of full spectrum fitting

Koleva¹,

Prugniel²,

Ocvirk³

et al. 2008

Monthly Notices RAS

188

251

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Fitting whole spectra at intermediate spectral resolution (R = 1000-3000), to derive physical properties of stellar populations, appears as an optimized alternative to methods based on spectrophotometric indices: it uses all the redundant information contained in the signal. This paper addresses the validation of the method and it investigates the quality of the population models together with the reliability of the fitting procedures. Our method compares observed optical spectra with models to derive the age, metallicity and line broadening due to the internal kinematics. It is insensitive to the shape of the continuum and the results are consistent with Lick indices but three times more precise. We are using two algorithms: STECKMAP, a nonparametric regularized program and NBURSTS a parametric non-linear minimization.We compare three spectral synthesis models for single stellar populations (SSPs): Pegase-HR, Galaxev and Vazdekis/Miles, and we analyse spectra of Galactic clusters whose populations are known from studies of colour-magnitude diagrams (CMD) and spectroscopy of individual stars.We find the following.(1) The quality of the models critically depends on the stellar library they use, and in particular on its coverage in age, metallicity and surface gravity of the stars. Pegase-HR and Vazdekis/Miles are consistent, while the comparison between Pegase-HR and Bruzual & Charlot shows some systematics reflecting the limitations of the stellar library (STELIB) used to generate the latter models. (2) The two fitting programs are consistent. (3) For globular clusters and M67 spectra, the method restitutes metallicities in agreement with spectroscopy of stars with a precision of 0.14 dex. (4) The spectroscopic ages are very sensitive to the presence of a blue horizontal branch (BHB) or of blue stragglers. A BHB morphology results in a young SSP-equivalent age. Fitting a free amount of blue stars in addition to the SSP model to mimic the BHB improves and stabilizes the fit and restores ages in agreement with CMDs studies. This method is potentially able to disentangle age or BHB effects in extragalactic clusters. Full spectrum fitting is reliable method to derive the parameters of a stellar population.

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Section: Analysis Of Galactic Clustersmentioning

confidence: 99%

Spectroscopic ages and metallicities of stellar populations: validation of full spectrum fitting

Koleva¹,

Prugniel²,

Ocvirk³

et al. 2008

Monthly Notices RAS

188

251

View full text Add to dashboard Cite

show abstract

“…Previous photometric analyses are present in the literature for all the clusters analysed in this work. Our photometry has been compared with the photometric catalogue already published (Krusberg & Chaboyer 2006 for NGC 188; Kassis et al 1997 for NGC 2204; Bonifazi et al 1990 for NGC 2243; Sharma et al 2006 for NGC 2420 and Jeffries et al 2001 for NGC 2516). The mean magnitude differences found are always smaller than 0.02 mag in both passbands, consistent with no systematic offset.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

The fraction of binary systems in the core of five Galactic open clusters

Sollima¹,

Carballo‐Bello²,

Beccari³

et al. 2010

Monthly Notices of the Royal Astronomical Society

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We used deep wide-field photometric observations to derive the fraction of binary systems in a sample of five high-latitude Galactic open clusters. By analysing the colour distribution of main-sequence stars, we derived the minimum fraction of binary systems required to reproduce the observed colour-magnitude diagram morphologies. We found that all the analysed clusters contain a minimum binary fraction larger than 11 per cent within the core radius. The estimated global fractions of binary systems range from 35 to 70 per cent depending on the cluster. The comparison with homogeneous estimates performed in globular clusters indicates that open clusters hold a significantly higher fraction of binary systems, as predicted by theoretical models and N-body simulations. A dependence of the relative fraction of binary systems on the cluster mass has been detected, suggesting that the binary disruption within the cluster core is the dominant process that drives the fraction of binaries in stellar systems.

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“…4) in brackets of column (11). The last column is the references for the data (note that the values of N 2 and N BS in all clusters come from AL07): (1) AL07; (2) Vallenari, Carraro & Richichi 2000; (3) Manteiga et al 1995; (4) Bragaglia et al 2000; (5) Claria et al 2003; (6) Hebb, Wyse & Gilmore 2004; (7) van Leeuwen 1999; (8) Krusberg & Chaboyer 2006; (9) Kharchenko et al 2005; (10) Loktin & Marktin 1994; (11) Dias et al 2002; (12) Marshall et al 2005; (13) Lapasset, Claria & Mermilliod 2000; (14) VandenBerg & Stetson 2004; (15) Eggen 1981; (16) Sarajedini et al 2004; (17) Luck 1994; (18) Paunzen & Maitzen 2001; (19) Prosser, Randich & Stauffer 1996; (20) Sagar, Munari & de Boer 2001; (21) Surendiranath et al 1990; (22) Carraro & Patat 2001; (23) Balona & Laney 1995; (24) Ahumada 2005; (25) Andreuzzi et al 2004.…”

Section: The Role Of Pbe For Producing Bss In Galactic Open Clustersmentioning

confidence: 99%

Primordial binary evolution and blue stragglers

Chen

Han

2009

Monthly Notices of the Royal Astronomical Society

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Blue stragglers can significantly enhance the spectral energy towards short wavelengths, especially in ultraviolet and blue bands. Much evidence shows that blue stragglers are relevant to primordial binaries. In this paper, we systematically studied blue stragglers produced from primordial binary evolution via a binary population synthesis approach, and examined their contribution to the integrated spectral energy distributions of the host clusters. The mass transfer efficiency, β, is an important parameter for the final products (then blue stragglers) after mass transfer, and it is set to be 0.5 except for case A binary evolution. The study shows that primordial binary evolution may produce blue stragglers at any given times, and that different evolutionary channels correspond to blue stragglers in different visual magnitude regions (in V band) on the colour-magnitude diagram (CMD) of clusters. The specific frequency of blue stragglers obtained from primordial binary evolution decreases with time first, and then increases again when the age is larger than 10 Gyr, while that from angular momentum loss induced by magnetic braking in low-mass binaries increases with time and exceeds that of primordial binary evolution in a population older than 3 Gyr. Meanwhile, blue stragglers resulting from primordial binary evolution are dominant contributors to the integrated spectral energy distributions (ISEDs) in ultraviolet and blue bands in a population between 0.3 and 2.0 Gyr. The value of β significantly affects the final results, e.g. the specific frequency of blue stragglers decreasing with β, blue stragglers produced from a high value of β being more massive, then contributing more to the ISEDs of the host clusters. For old open clusters, the assumption of β = 1 when the primary is in HG at the onset of mass transfer matches the observations better than that of β = 0.5 from the locations of blue stragglers on the CMDs. Our study also shows that, for most Galactic open clusters, the specific frequency of blue stragglers obtained from our simulations is lower than that of observations, which is puzzling. Nevertheless, primordial binary evolution cannot account for all blue stragglers observed in old clusters.

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UBVICCD Photometry of the Old Open Cluster Berkeley 17

Cited by 18 publications

References 55 publications

Spectroscopic ages and metallicities of stellar populations: validation of full spectrum fitting

Spectroscopic ages and metallicities of stellar populations: validation of full spectrum fitting

The fraction of binary systems in the core of five Galactic open clusters

Primordial binary evolution and blue stragglers

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