A Family Picture: Tracing the Dynamical Path of the Structural Properties of Multiple Populations in Globular Clusters

Dalessandro, E.; Cadelano, Mario; Vesperini, Enrico; Martocchia, S.; Ferraro, F. R.; Lanzoni, B.; Bastian, N.

doi:10.3847/2041-8213/ab45f7

Cited by 50 publications

(57 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The comparison between their radial distributions, performed via a 2-sided Kolmogorov-Smirnov test, reveals P2 stars to be more centrally concentrated than P1 stars, at a 3-sigma level. This result is in agreement with the findings of Dalessandro et al (2019), who adopted A + (i.e. the area within the cumulative distribution functions of P1 and P2) as a parameter to classify concentration differences between the multiple populations within a cluster.…”

Section: A2 the Impact Of Interstellar Absorption On Nad Linessupporting

confidence: 92%

Leveraging HST with MUSE – I. Sodium abundance variations within the 2-Gyr-old cluster NGC 1978

Saracino

Kamann

Usher

et al. 2020

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

Nearly all of the well studied ancient globular clusters (GCs), in the Milky Way and in nearby galaxies, show star-to-star variations in specific elements (e.g., He, C, N, O, Na, Al), known as “multiple populations” (MPs). However, MPs are not restricted to ancient clusters, with massive clusters down to ∼2 Gyr showing signs of chemical variations. This suggests that young and old clusters share the same formation mechanism but most of the work to date on younger clusters has focused on N-variations. Initial studies even suggested that younger clusters may not host spreads in other elements beyond N (e.g., Na), calling into question whether these abundance variations share the same origin as in the older GCs. In this work, we combine HST photometry with VLT/MUSE spectroscopy of a large sample of RGB stars (338) in the Large Magellanic Cloud cluster NGC 1978, the youngest globular to date with reported MPs in the form of N-spreads. By combining the spectra of individual RGB stars into N-normal and N-enhanced samples, based on the “chromosome map” derived from HST, we search for mean abundance variations. Based on the NaD line, we find a Na-difference of Δ[Na/Fe]=0.07 ± 0.01 between the populations. While this difference is smaller than typically found in ancient GCs (which may suggest a correlation with age), this result further confirms that the MP phenomenon is the same, regardless of cluster age and host galaxy. As such, these young clusters offer some of the strictest tests for theories on the origin of MPs.

show abstract

Section: A2 the Impact Of Interstellar Absorption On Nad Linessupporting

confidence: 92%

Leveraging HST with MUSE – I. Sodium abundance variations within the 2-Gyr-old cluster NGC 1978

Saracino

Kamann

Usher

et al. 2020

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…An initially more concentrated P2 is a common feature of essentially all scenarios put forward to explain multiple populations and appears to be in agreement with the observed density profiles and kinematics of the populations in most Galactic globular clusters today (e.g. Lardo et al 2011;Richer et al 2013;Bellini et al 2015;Dalessandro et al 2019).…”

Section: Introductionsupporting

confidence: 78%

The binary content of multiple populations in NGC 3201

Kamann

Giesers

Bastian

et al. 2020

A&A

Self Cite

View full text Add to dashboard Cite

We investigate the binary content of the two stellar populations that coexist in the globular cluster NGC 3201. Previous studies of binary stars in globular clusters have reported higher binary fractions in their first populations (P1, having field-like abundances) compared to their second populations (P2, having anomalous abundances). This is interpreted as evidence for the latter forming more centrally concentrated. In contrast to previous studies, our analysis focuses on the cluster centre, where comparable binary fractions between the populations are predicted because of the short relaxation times. However, we find that even in the centre of NGC 3201, the observed binary fraction of P1 is higher, (23.1 ± 6.2)% compared to (8.2 ± 3.5)% in P2. Our results are difficult to reconcile with a scenario where the populations only differ in their initial concentrations, but instead suggests that the populations also formed with different fractions of binary stars.

show abstract

“…Columns report the following information: name of the cluster, mask number, exposure times, total number of stars targeted, mean SNR with 1 dispersion, age of the cluster, mass of the cluster, metallicity of the cluster [Fe/H], distance modulus ( − ), extinction coefficient , stellar mass of a typical RGB star of the cluster ★ , half light radius ℎ . Goudfrooĳ et al (2014), 2 Westerlund (1997), 3 Dalessandro et al (2019).…”

Section: Observations and Data Reductionmentioning

confidence: 99%

“…Nardiello et al 2015;Martocchia et al 2018b;Saracino et al 2020a), (v) commonly the anomalous population is more centrally concentrated than the "normal", field-like population, although this seems to depend on the dynamical age of the clusters (e.g. Dalessandro et al 2019). These are just a few of the peculiarities that a MP formation/evolution model has to satisfy.…”

Section: Introductionmentioning

confidence: 97%

On the Nitrogen variation in ∼2 Gyr old massive star clusters in the large Magellanic Cloud

Martocchia

Lardo

Rejkuba

et al. 2021

Monthly Notices of the Royal Astronomical Society

Self Cite

View full text Add to dashboard Cite

We present ESO/VLT FORS2 low resolution spectroscopy of red giant branch stars in three massive, intermediate age (∼1.7 − 2.3 Gyr) star clusters in the Large Magellanic Cloud. We measure CH and CN index bands at 4300Å and 3883Å, as well as [C/Fe] and [N/Fe] abundance ratios for 24, 21 and 12 member stars of NGC 1978, NGC 1651, NGC 1783, respectively. We find a significant intrinsic spread in CN in NGC 1978 and NGC 1651, a signal of multiple stellar populations (MPs) within the clusters. On the contrary, we report a null CN spread in NGC 1783 within our measurement precision. For NGC 1978, we separated the two populations in the CN distribution and we translated the CN spread into an internal N variation Δ[N/Fe]=0.63 ± 0.49 dex. For NGC 1651 and NGC 1783, we put upper limits on the N abundance variations of Δ[N/Fe]≤0.2, 0.4 dex, respectively. The spectroscopic analysis confirms previous results from HST photometry, where NGC 1978 was found to host MPs in the form of N spreads, while slightly younger clusters (e.g. NGC 1783, < 2 Gyr old) were not, within the limits of the uncertainties. It also confirms that intermediate age massive clusters show lower N abundance variations with respect to the ancient globular clusters, although this is in part due to the effect of the first dredge up at these stellar masses, as recently reported in the literature. We stress the importance of future studies to estimate the initial N abundance variations, free of stellar evolutionary mixing processes, by observing unevolved stars in young clusters.

show abstract

A Family Picture: Tracing the Dynamical Path of the Structural Properties of Multiple Populations in Globular Clusters

Cited by 50 publications

References 54 publications

Leveraging HST with MUSE – I. Sodium abundance variations within the 2-Gyr-old cluster NGC 1978

Leveraging HST with MUSE – I. Sodium abundance variations within the 2-Gyr-old cluster NGC 1978

The binary content of multiple populations in NGC 3201

On the Nitrogen variation in ∼2 Gyr old massive star clusters in the large Magellanic Cloud

Contact Info

Product

Resources

About