Observing multiple stellar populations with VLT/FORS2

Nardiello, D.; Milone, A. P.; Piotto, G.; Marino, A. F.; Bellini, Andrea; Cassisi, S.

doi:10.1051/0004-6361/201424117

Cited by 89 publications

(122 citation statements)

References 68 publications

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“…It clearly reveals that SG stars are significantly more centrally concentrated than the FG sub-population, as assessed by means of a Kolmogorov-Smirnov test. This is in agreement with what observed in most Galactic GCs studied so far, apart from NGC 6362 (Dalessandro et al 2014a), NGC 6752 and NGC 6121 (Nardiello et al 2015), where FG and SG are totally spatially mixed, and M 15 (Larsen et al 2015), where FG have been suggested to be more segregated than SG stars.…”

Section: Results From the Photometric Data-setsupporting

confidence: 92%

Multiple Populations in the Old and Massive Small Magellanic Cloud Globular Cluster NGC 121*

Dalessandro

Lapenna

Mucciarelli

et al. 2016

ApJ

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We used a combination of optical and near-UV Hubble Space Telescope photometry and FLAMES/ESO-VLT high-resolution spectroscopy to characterize the stellar content of the old and massive globular cluster (GC) NGC 121 in the Small Magellanic Cloud (SMC). We report on the detection of multiple stellar populations, the first case in the SMC stellar cluster system. This result enforces the emerging scenario in which the presence of multiple stellar populations is a distinctive-feature of old and massive GCs regardless of the environment, as far as the light element distribution is concerned. We find that second population (SG) stars are more centrally concentrated than first (FG) ones. More interestingly, at odds with what typically observed in Galactic GCs, we find that NGC 121 is the only cluster so far to be dominated by FG stars that account for more than 65% of the total cluster mass. In the framework where GCs were born with a 90 − 95% of FG stars, this observational finding would suggest that either NGC 121 experienced a milder stellar mass-loss with respect to Galactic GCs or it formed a smaller fraction of SG stars.

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Section: Results From the Photometric Data-setsupporting

confidence: 92%

Multiple Populations in the Old and Massive Small Magellanic Cloud Globular Cluster NGC 121*

Dalessandro

Lapenna

Mucciarelli

et al. 2016

ApJ

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“…Again we see that the higher alpha enrichment requires a slightly lower [Fe/H] and higher helium for both populations. As with NGC 5272, we find a difference in helium abundances of the populations in the cluster to be slightly greater than that suggested by recent studies (Nardiello et al 2015). Nardiello et al (2015) and this study examine both MS and RGB stars, making for a more direct comparison than with NGC 5272.…”

Section: Ngc 6352contrasting

confidence: 47%

“…As with NGC 5272, we find a difference in helium abundances of the populations in the cluster to be slightly greater than that suggested by recent studies (Nardiello et al 2015). Nardiello et al (2015) and this study examine both MS and RGB stars, making for a more direct comparison than with NGC 5272. Nardiello et al (2015) assume a metallicity and helium for the first population in order to determine the best helium value for the second population, examining the needed increase in helium in steps to find the best fit to the data.…”

Section: Ngc 6352contrasting

confidence: 47%

“…Shortly thereafter, Bedin et al (2004) observed ω Cen with deep, high-precision HST images, exposing a variety of intricacies never seen before in a globular cluster. More recent studies Milone et al 2009Milone et al , 2012aMilone et al , 2012bMilone et al , 2013Nardiello et al 2015;Piotto et al 2015) demonstrate that many globular clusters have undergone more than one epoch of star formation, a conclusion in dramatic contrast with the classical "simple stellar population" hypothesis.…”

Section: Introductionmentioning

confidence: 92%

“…Metal-rich clusters ([Fe/ H]>-1.0) are often difficult to model, and hence fit, with A recent study by Nardiello et al (2015), also using photometry from the UVIS treasury, finds that the two populations in NGC 6352 differ by ∼0.03 in helium abundance through examination of RGB fiducials.…”

Section: Ngc 6352mentioning

confidence: 99%

See 2 more Smart Citations

Bayesian Analysis of Two Stellar Populations in Galactic Globular Clusters. Ii. NGC 5024, NGC 5272, and NGC 6352

Wagner-Kaiser

Stenning

Robinson

et al. 2016

ApJ

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We use Cycle 21 Hubble Space Telescope (HST) observations and HST archival Advanced Camera for Surveys Treasury observations of Galactic Globular Clusters to find and characterize two stellar populations in NGC 5024 (M53), NGC 5272 (M3), and NGC 6352. For these three clusters, both single and double-population analyses are used to determine a best fit isochrone(s). We employ a sophisticated Bayesian analysis technique to simultaneously fit the cluster parameters (age, distance, absorption, and metallicity) that characterize each cluster. For the twopopulation analysis, unique population level helium values are also fit to each distinct population of the cluster and the relative proportions of the populations are determined. We find differences in helium ranging from ∼0.05 to 0.11 for these three clusters. Model grids with solar α-element abundances ([α/Fe]=0.0) and enhanced α-elements ([α/Fe]=0.4) are adopted.

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The HST Large Programme on NGC 6752 ‐ V. Differences in luminosity and mass function among stellar populations

Scalco,

Gerasimov,

Bedin

et al. 2024

Astron Nachr

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We exploit the astro‐photometric dataset of the multi‐epoch infrared parallel field of a Hubble Space Telescope Large Programme aimed at studying the faintest stars of the globular cluster NGC 6752 to determine the luminosity and mass functions of the multiple stellar populations of this cluster. Thanks to the measurement of proper motions and deeper completeness, the results presented in this paper represent a significant improvement over those of previous studies. We successfully derived membership probabilities reaching stars as faint as , allowing us to reliably distinguish the three main stellar populations detected within this cluster. We employed a new set of model isochrones that have been individually fit to the colour–magnitude diagram of each population. We present a comprehensive analysis of the luminosity and mass functions for three stellar populations within NGC 6752. Notably, our findings reveal differences in the present‐day luminosity and mass functions of first‐generation and second‐generation stars; these differences are consistent with the manifestation of the effects of dynamical processes acting on populations with different initial spatial distributions. Finally, we publicly release the catalogues with positions, photometry, proper motions and memberships probabilities, as well as the stacked‐image atlases and all newly calculated stellar models.

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Observing multiple stellar populations with VLT/FORS2

Cited by 89 publications

References 68 publications

Multiple Populations in the Old and Massive Small Magellanic Cloud Globular Cluster NGC 121*

Multiple Populations in the Old and Massive Small Magellanic Cloud Globular Cluster NGC 121*

Bayesian Analysis of Two Stellar Populations in Galactic Globular Clusters. Ii. NGC 5024, NGC 5272, and NGC 6352

The HST Large Programme on NGC 6752 ‐ V. Differences in luminosity and mass function among stellar populations

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