Extended Main-sequence Turn-offs in Intermediate-age Star Clusters: Stellar Rotation Diminishes, but Does Not Eliminate, Age Spreads

Goudfrooij, Paul; Girardi, L.; Correnti, Matteo

doi:10.3847/1538-4357/aa7fb7

Cited by 59 publications

(51 citation statements)

References 53 publications

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“…The interpretation of the eMSTO is still debated and it is not clear whether an age variation, together with a range of stellar rotation, is needed to reproduce the observations (e.g. Goudfrooij et al 2017).…”

Section: The Split Ms and The Extended Mstomentioning

confidence: 99%

Multiple stellar populations in Magellanic Cloud clusters – VI. A survey of multiple sequences and Be stars in young clusters

Milone

Marino

Criscienzo

et al. 2018

Monthly Notices of the Royal Astronomical Society

109

184

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The split main sequences (MSs) and extended MS turnoffs (eMSTOs) detected in a few young clusters have demonstrated that these stellar systems host multiple populations differing in a number of properties such as rotation and, possibly, age.We analyze Hubble Space Telescope photometry for thirteen clusters with ages between ∼40 and ∼1000 Myrs and of different masses. Our goal is to investigate for the first time the occurrence of multiple populations in a large sample of young clusters.We find that all the clusters exhibit the eMSTO phenomenon and that MS stars more massive than ∼1.6 M ⊙ define a blue and red MS, with the latter hosting the majority of MS stars. The comparison between the observations and isochrones suggests that the blue MSs are made of slow-rotating stars, while the red MSs host stars with rotational velocities close to the breakup value.About half of the bright MS stars in the youngest clusters are H-alpha emitters. These Be stars populate the red MS and the reddest part of the eMSTO thus supporting the idea that the red MS is made of fast rotators.We conclude that the split MS and the eMSTO are a common feature of young clusters in both Magellanic Clouds. The phenomena of a split MS and an eMSTO occur for stars that are more massive than a specific threshold which is independent of the host-cluster mass.As a by-product, we report the serendipitous discovery of a young SMC cluster, GAL-FOR1.

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Section: The Split Ms and The Extended Mstomentioning

confidence: 99%

Multiple stellar populations in Magellanic Cloud clusters – VI. A survey of multiple sequences and Be stars in young clusters

Milone

Marino

Criscienzo

et al. 2018

Monthly Notices of the Royal Astronomical Society

109

184

View full text Add to dashboard Cite

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“…Vertical black dashed lines indicate ages cited from literature in Section 2; transparent cyan solid lines indicate the best-fit age found by the Ω-model for the respective cluster. The black solid curves are pseudo-age distributions from Goudfrooij et al (2014) and Goudfrooij et al (2017) for NGC 2203 and 2249 (respectively) for comparison.…”

Section: Mock Testsmentioning

confidence: 99%

Combined Effects of Rotation and Age Spreads on Extended Main-Sequence Turn Offs

Gossage¹,

Conroy²,

Dotter³

et al. 2019

ApJ

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The extended main sequence turn offs (eMSTOs) of several young to intermediate age clusters are examined in the Magellanic Clouds and the Milky Way. We explore the effects of extended star formation (eSF) and a range of stellar rotation rates on the behavior of the color-magnitude diagram (CMD), paying particular attention to the MSTO. We create synthetic stellar populations based on MESA stellar models to simulate observed Hubble Space Telescope and Gaia star cluster data. We model the effect of rotation as a non-parametric distribution, allowing for maximum flexibility. In our models the slow rotators comprise the blueward, and fast rotators the redward portion of the eMSTO. We simulate data under three scenarios: non-rotating eSF, a range of rotation rates with a single age, and a combination of age and rotation effects. We find that two of the five clusters (the youngest and oldest) favor an age spread, but these also achieve the overall worst fits of all clusters. The other three clusters show comparable statistical evidence between rotation and an age spread. In all five cases, a rotation rate distribution alone is capable of qualitatively matching the observed eMSTO structure. In future work, we aim to compare our predicted V sin i with observations in order to better constrain the physics related to stellar rotation.

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“…D' Antona et al 2015;Li et al 2017;Cordoni et al 2018;Marino et al 2018c;Marino et al 2018a;Milone et al 2018a), rather than to chemical variations, and are possibly associated with age spreads (e.g. Goudfrooij et al 2011Goudfrooij et al , 2017. These observations have prompted the idea that MPs may have formed exclusively at high redshift.…”

Section: Introductionmentioning

confidence: 98%

Multiple populations in globular clusters and their parent galaxies

Milone

Marino²,

Costa

et al. 2019

Monthly Notices of the Royal Astronomical Society

101

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The 'chromosome map' diagram (ChM) proved a successful tool to identify and characterize multiple populations (MPs) in 59 Galactic Globular Clusters (GCs). Here, we construct ChMs for 11 GCs of both Magellanic Clouds (MCs) and with different ages to compare MPs in Galactic and extra-Galactic environments, and explore whether this phenomenon is universal through 'place' and 'time'. MPs are detected in five clusters. The fractions of 1G stars, ranging from ∼50% to >80%, are significantly higher than those observed in Galactic GCs with similar present-day masses. By considering both Galactic and MC clusters, the fraction of 1G stars exhibits: (i) a strong anti-correlation with the present-day mass, and (ii) with the present-day mass of 2G stars; (iii) a mild anti-correlation with 1G present-day mass. All Galactic clusters without MPs have initial masses smaller than ∼ 1.5 · 10 5 M but a mass threshold governing the occurrence of MPs seems challenged by massive simple-population MC GCs; (iv) Milky Way clusters with large perigalactic distances typically host larger fractions of 1G stars, but the difference disappears when we use initial cluster masses. These facts are consistent with a scenario where the stars lost by GCs mostly belong to the 1G. By exploiting recent work based on Gaia, half of the known Type II GCs appear clustered in a distinct region of the integral of motions space, thus suggesting a common progenitor galaxy. Except for these Type II GCs, we do not find any significant difference in the MPs between clusters associated with different progenitors.

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Extended Main-sequence Turn-offs in Intermediate-age Star Clusters: Stellar Rotation Diminishes, but Does Not Eliminate, Age Spreads

Cited by 59 publications

References 53 publications

Multiple stellar populations in Magellanic Cloud clusters – VI. A survey of multiple sequences and Be stars in young clusters

Multiple stellar populations in Magellanic Cloud clusters – VI. A survey of multiple sequences and Be stars in young clusters

Combined Effects of Rotation and Age Spreads on Extended Main-Sequence Turn Offs

Multiple populations in globular clusters and their parent galaxies

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