The Small Magellanic Cloud star cluster NGC 458. A new <i>UBVI</i> photometric study

Alcaino, G.; Alvarado, F.; Borissova, J.; Kurtev, R.

doi:10.1051/0004-6361:20030069

Cited by 12 publications

(9 citation statements)

References 14 publications

(21 reference statements)

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“…(Noël et al 2007). They are also in good agreement with previous measurements on SMC intermediate-age clusters (e.g., Alcaino et al 2003;Hunter et al 2003;Rochau et al 2007). The reddening values found for Cluster A and B164 correspond to an extinction of A V % 0:1 mag and A V % 0:2 mag, respectively, assuming an extinction law Koornneef 1983).…”

Section: Interstellar Reddeningsupporting

confidence: 92%

The Initial Mass Function of the Stellar Association NGC 602 in the Small Magellanic Cloud withHubble Space TelescopeACS Observations

Schmalzl

Gouliermis

Dolphin

et al. 2008

ApJ

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We present our photometric study of the stellar association NGC 602 in the wing of the Small Magellanic Cloud (SMC). The data were taken in the filters F555W and F814W using the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope (HST ). Photometry was performed using the ACS module of the stellar photometry package DOLPHOT. We detected more than 5500 stars with a magnitude range of 14 P m 555 P 28 mag. Three prominent stellar concentrations are identified with star counts in the observed field, the association NGC 602 itself, and two clusters, one of them not being currently in any known catalog. The color-magnitude diagrams (CMDs) of both clusters show features typical for young open clusters, while that of the association reveals bright main-sequence (MS) and faint preYmain-sequence ( PMS) stars as the members of the system. We construct the initial mass spectrum (IMS) of the association by applying an age-independent method of counting the PMS stars within evolutionary tracks, while for the bright MS stars we transform their magnitudes to masses with the use of mass-luminosity relations. The IMS of NGC 602 is found to be well represented by a single power law, corresponding to an initial mass function (IMF) of slope À % À1:2 for 1 P M/M P 45. This indicates that the shape of the IMF of a star-forming system in the SMC for stars with masses higher than 1 M seems to be quite similar to the field IMF in the solar neighborhood.

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Section: Interstellar Reddeningsupporting

confidence: 92%

The Initial Mass Function of the Stellar Association NGC 602 in the Small Magellanic Cloud withHubble Space TelescopeACS Observations

Schmalzl

Gouliermis

Dolphin

et al. 2008

ApJ

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“…In view of the common occurrence of BSs in MC star clusters (e.g. Johnson et al 1999; Alcaino et al 2003), and given that our results for the comparatively rich MC clusters (at least, with respect to the Galactic OCs) are statistically robust, we have a reason to believe that the BS effect discussed in this paper for ESO 121‐SC03 may not be an exception. BS contributions (to the conventional SSPs) measured based on other MC star clusters are expected to be at a similar level as for ESO 121‐SC03, and likely follow the same trend as for our previous results based on Galactic OCs covering a wide age range (Deng et al 1999; XD05; XDH07): the clusters' age and/or metallicity estimates will be underestimated significantly, by a factor of 2–4, based on fits of SSPs to either spectra or broad‐band colours.…”

Section: Discussionmentioning

confidence: 61%

Simple stellar population models as probed by the Large Magellanic Cloud star cluster ESO 121-SC03

Xin

Deng

Grijs

et al. 2008

Monthly Notices RAS

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The presence of blue straggler stars (BSs) in star clusters has proven a challenge to conventional simple stellar population (SSP) models. Conventional SSP models are based on the evolution theory of single stars. Meanwhile, the typical locations of BSs in the colour-magnitude diagram of a cluster are brighter and bluer than the main-sequence turn-off point. Such loci cannot be predicted by single-star evolution theory. However, stars with such properties contribute significantly to the integrated light of the cluster. In this paper, we reconstruct the integrated properties of the Large Magellanic Cloud cluster European Southern Observatory (ESO) 121-SC03, the only cluster populating the well-known age gap in the cluster age distribution, based on a detailed exploration of the individual cluster stars, and with particular emphasis on the cluster's BSs. We find that the integrated light properties of ESO 121-SC03 are dramatically modified by its BS component. The integrated spectral energy distribution (ISED) flux level is significantly enhanced towards shorter wavelengths, and all broad-band colours become bluer. When fitting the fully integrated ISED of this cluster based on conventional SSP models, the best-fitting values of age and metallicity are significantly underestimated compared to the true cluster parameters. The age underestimate is ∼40 per cent if we only include the BSs within the cluster's half-light radius and ∼60 per cent if all BSs are included. The corresponding underestimates of the cluster's metallicity are ∼30 and ∼60 per cent, respectively. The populous star clusters in the Magellanic Clouds are ideal objects to explore the potential importance of BSs for the integrated light properties of more distant unresolved star clusters in a statistically robust manner, since they cover a large range in age and metallicity.Even using improved observational technologies, the number of galaxies with resolved stellar contents is limited. Comparison of the observed integrated spectral properties with models of 'simple' stellar populations (SSPs; single age, single-metallicity stellar populations), i.e. using the so-called population synthesis technique, is therefore a practical approach to studying the formation and the evolution processes in unresolved galaxies and their components. As the basic building blocks of the evolutionary population synthesis (EPS) method, conventional SSP models are generally constructed based on the evolution theory of single stars. (We specify the con-E-mail: y.xin@sheffield.ac.uk ventional SSP models throughout this paper as the theoretical SSP models based on single-star evolution theory.) Thus far, accuracy assessments of the existing suites of conventional SSP models have not yet adequately considered a potentially significant problem revealed by observations of star clusters.By assuming that all the original member stars within a cluster are born at the same time from the same progenitor molecular cloud, so that they have the same age and metallicity, star clusters are g...

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“…Of the more recent determinations, Alcaino et al (2003), Glatt et al (2008c), andCignoni et al (2009) base their distance estimates on star clusters located well outside the SMC's main body, with the exception of NGC 416 studied by Glatt et al (2008c), for which they determine (m − M ) 0 = 18.90 ± 0.07 mag. Pietrzyński et al (2003) and Sabbi et al (2009) focus on field regions and find, respectively, (m − M ) 0 = 18.93 ± 0.03 mag (which is affected by lingering systematic uncertainties in the K band) versus (m − M ) 0 = 18.89 ± 0.45 mag (field SFH1) and (m − M ) 0 = 18.97 ± 0.27 mag (field SFH4).…”

Section: Stellar Population Tracersmentioning

confidence: 99%

Clustering of Local Group Distances: Publication Bias or Correlated Measurements? Iii. The Small Magellanic Cloud

Grijs

Bono

2015

110

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Aiming at providing a firm mean distance estimate to the Small Magellanic Cloud (SMC), and thus to place it within the internally consistent Local Group distance framework we recently established, we compiled the current-largest database of published distance estimates to the galaxy. Based on careful statistical analysis, we derive mean distance estimates to the SMC using eclipsing binary systems, variable stars, stellar population tracers, and star cluster properties. Their weighted mean leads to a final recommendation for the mean SMC distance of (m − M ) SMC 0 = 18.96 ± 0.02 mag, where the uncertainty represents the formal error. Systematic effects related to lingering uncertainties in extinction corrections, our physical understanding of the stellar tracers used, and the SMC's complex geometry-including its significant line-of-sight depth, its irregular appearance which renders definition of the galaxy's center uncertain, as well as its high inclination and possibly warped disk-may contribute additional uncertainties possibly exceeding 0.15-0.20 mag.

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The Small Magellanic Cloud star cluster NGC 458. A new UBVI photometric study

Cited by 12 publications

References 14 publications

The Initial Mass Function of the Stellar Association NGC 602 in the Small Magellanic Cloud withHubble Space TelescopeACS Observations

The Initial Mass Function of the Stellar Association NGC 602 in the Small Magellanic Cloud withHubble Space TelescopeACS Observations

Simple stellar population models as probed by the Large Magellanic Cloud star cluster ESO 121-SC03

Clustering of Local Group Distances: Publication Bias or Correlated Measurements? Iii. The Small Magellanic Cloud

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