When Does the Onset of Multiple Stellar Populations in Star Clusters Occur? Detection of Enriched Stellar Populations in NGC 2121

Li, Chengyuan; Grijs, Richard de

doi:10.3847/1538-4357/ab153b

Cited by 17 publications

(16 citation statements)

References 53 publications

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“…(iv) The oldest one with a modest population of C stars (just one) appears to be NGC 2121, for which HST data provides ages between 2.5 Gyr (Martocchia et al 2019) and 3.2 Gyr (Rich et al 2001;Li & de Grijs 2019), and hence a turn-off mass just slightly smaller than NGC 1978;…”

Section: And M Maxmentioning

confidence: 99%

Constraining the thermally pulsing asymptotic giant branch phase with resolved stellar populations in the Large Magellanic Cloud

Pastorelli

Marigo

Girardi

et al. 2020

Monthly Notices of the Royal Astronomical Society

129

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Reliable models of the thermally pulsing asymptotic giant branch (TP-AGB) phase are of critical importance across astrophysics, including our interpretation of the spectral energy distribution of galaxies, cosmic dust production, and enrichment of the interstellar medium. With the aim of improving sets of stellar isochrones that include a detailed description of the TP-AGB phase, we extend our recent calibration of the AGB population in the Small Magellanic Cloud (SMC) to the more metal rich Large Magellanic Cloud (LMC). We model the LMC stellar populations with the trilegal code, using the spatially-resolved star formation history derived from the VISTA survey. We characterize the efficiency of the third dredge-up by matching the star counts and the Ks-band luminosity functions of the AGB stars identified in the LMC. In line with previous findings, we confirm that, compared to the SMC, the third dredge-up in AGB stars of the LMC is somewhat less efficient, as a consequence of the higher metallicity. The predicted range of initial mass of C-rich stars is between ${M_{\rm i}}\approx 1.7 - 3~{\mathrm{M}_{\odot }}$ at ${Z_{\rm i}}= 0.008$. We show how the inclusion of new opacity data in the carbon star spectra will improve the performance of our models. We discuss the predicted lifetimes, integrated luminosities and mass-loss rate distributions of the calibrated models. The results of our calibration are included in updated stellar isochrones publicly available.

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Section: And M Maxmentioning

confidence: 99%

Constraining the thermally pulsing asymptotic giant branch phase with resolved stellar populations in the Large Magellanic Cloud

Pastorelli

Marigo

Girardi

et al. 2020

Monthly Notices of the Royal Astronomical Society

129

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“…However, these scenarios have a number of significant drawbacks that call into question their feasibility, the most important ones being: (i) the mass budget problem (e.g., Prantzos & Charbonnel 2006;Larsen et al 2012), (ii) the positive correlation between MPs and cluster mass (abundance spread and fraction of P2 stars - Carretta et al 2010;Schiavon et al 2013;Bastian & Lardo 2015;Milone et al 2017), (iii) the inability to reproduce some of the detailed observed chemical patterns (e.g., Lardo et al 2018;Cabrera-Ziri et al 2019), (iv) the lack of observational evidence for multiple episodes of star-formation within young massive clusters (e.g., Cabrera-Ziri et al 2014;Martocchia et al 2018b;Saracino et al 2020a) and (v) the observed trends of MP properties with cluster age (Martocchia et al 2019;Li & de Grijs 2019).…”

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confidence: 99%

Leveraging HST with MUSE: II. Na-abundance variations in intermediate age star clusters

Martocchia

Kamann

Saracino

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Ancient (>10 Gyr) globular clusters (GCs) show chemical abundance variations in the form of patterns among certain elements, e.g. N correlates with Na and anti-correlates with O. Recently, N abundance spreads have also been observed in massive star clusters that are significantly younger than old GCs, down to an age of ∼2 Gyr. However, so far N has been the only element found to vary in such young objects. We report here the presence of Na abundance variations in the intermediate age massive star clusters NGC 416 (∼6.5 Gyr old) and Lindsay 1 (∼7.5 Gyr old) in the Small Magellanic Cloud, by combining HST and ESO-VLT MUSE observations. Using HST photometry we were able to construct “chromosome maps” and separate sub-populations with different N content, in the red giant branch of each cluster. MUSE spectra of individual stars belonging to each population were combined, resulting in high signal-to-noise spectra representative of each population, which were compared to search for mean differences in Na. We find a mean abundance variation of Δ[Na/Fe]=0.18 ± 0.04 dex for NGC 416 and Δ[Na/Fe]=0.24 ± 0.05 dex for Lindsay 1. In both clusters we find that the population that is enhanced in N is also enhanced in Na, which is the same pattern to the one observed in ancient GCs. Furthermore, we detect a bimodal distribution of core-helium burning Red Clump (RC) giants in the UV colour magnitude diagram of NGC 416. A comparison of the stacked MUSE spectra of the two RCs shows the same mean Na abundance difference between the two populations. The results reported in this work are a crucial hint that star clusters of a large age range share the same origin: they are the same types of objects, but only separated in age.

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“…Massari et al (2019) placed Pal 13 into a group of GCs related to a dwarf galaxy, named Sequoia, which was likely accreted 9 Gyr ago (Myeong et al 2019). The existence of MPs in Pal 13 supports the statement that this phenomenon is not unique in Galactic GCs formed in − situ (e.g., Li & de Grijs 2019;Milone et al 2020). Besides its proposed accreted origin, Pal 13 is suggested to be experiencing tidal stripping (Yepez et al 2019;Piatti & Fernández-Trincado 2020).…”

Section: And N Abundancesmentioning

confidence: 58%

“…Zooming out from the four low mass GCs that we mentioned above, we further investigate the current picture of MPs in the age-mass parameter plane (Figure 7 Li & de Grijs (2019), where most of the data come from Krause et al (2016). We have updated the stellar masses of low mass, old GCs using Baumgardt & Hilker (2018).…”

Section: Implication On Mp Investigationsmentioning

confidence: 99%

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Multiple populations in low mass globular clusters: Palomar 13

Tang,

Wang,

Huang

et al. 2020

Preprint

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Since the discovery of chemically peculiar stars in globular clusters in the last century, the study of multiple populations has become increasingly important, given that chemical inhomogeneity is found in almost all globular clusters. Despite various proposed theories attempting to explain this phenomenon, fitting all the observational evidence in globular clusters with one single theory remains notoriously difficult and currently unsuccessful. In order to improve existing models and motivate new ones, we are observing globular clusters at critical conditions, e.g., metal-rich end, metal-poor end, and low mass end. In this paper, we present our first attempt to investigate multiple populations in low mass globular clusters. We obtained low-resolution spectra around 4000 Å of 30 members of the globular cluster Palomar 13 using OSIRIS/Multi-object spectrograph mounted at the Gran Telescopio Canarias. The membership of red giant branch stars is confirmed by the latest proper motions from Gaia DR2 and literature velocities. After comparing the measured CN and CH spectral indices with those of the stellar models, we found a clear sign of nitrogen variation among the red giant branch stars. Palomar 13 may be the lowest mass globular cluster showing multiple populations.

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When Does the Onset of Multiple Stellar Populations in Star Clusters Occur? Detection of Enriched Stellar Populations in NGC 2121

Cited by 17 publications

References 53 publications

Constraining the thermally pulsing asymptotic giant branch phase with resolved stellar populations in the Large Magellanic Cloud

Constraining the thermally pulsing asymptotic giant branch phase with resolved stellar populations in the Large Magellanic Cloud

Leveraging HST with MUSE: II. Na-abundance variations in intermediate age star clusters

Multiple populations in low mass globular clusters: Palomar 13

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