Apparent age spreads in clusters and the role of stellar rotation

Niederhofer, Florian; Georgy, Cyril; Bastian, N.; Ekström, Sylvia

doi:10.1093/mnras/stv1791

Cited by 91 publications

(134 citation statements)

References 49 publications

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“…Brandt & Huang (2015a) used the rotating isochrones from the Geneva models (Ekström et al 2012;Georgy et al 2014) and showed that indeed stellar rotation can reproduce the eMSTOs observed in intermediate-age clusters. Niederhofer et al (2015a) used the same models and found that they predicted a relation between an apparent age spread and cluster age that matches the observations well. D 'Antona et al (2015) modelled the colour magnitude diagram (CMD) of NGC 1856 (∼300 Myr, ∼10…”

Section: Introductionmentioning

confidence: 79%

“…Milone et al 2015;Correnti et al 2015;Milone et al 2016); Bastian et al 2016. It is now clear that the extended main sequence turn-off (eMSTO) phenomenon is a common feature of massive young (Bastian & Silva-Villa 2013;Niederhofer et al 2015a;Milone et al 2016); Bastian et al 2016 andintermediate-age clusters (e.g. Milone et al 2009;Goudfrooij et al 2011;Piatti et al 2014b).…”

Section: Introductionmentioning

confidence: 99%

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Extended main sequence turn-offs in low mass intermediate-age clusters

Piatti

Bastian

2016

A&A

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We present an imaging analysis of four low mass stellar clusters ( < ∼ 5000 M ) in the outer regions of the LMC in order to shed light on the extended main sequence turn-off (eMSTO) phenomenon observed in high mass clusters. The four clusters have ages between 1−2 Gyr and two of them appear to host eMTSOs. The discovery of eMSTOs in such low mass clusters -more than 5 times less massive than the eMSTO clusters previously studied -suggests that mass is not the controlling factor in whether clusters host eMSTOs. Additionally, the narrow extent of the eMSTO in the two older clusters (∼2 Gyr) is in agreement with predictions of the stellar rotation scenario, as lower mass stars are expected to be magnetically braked, meaning that their colour magnitude diagrams should be better reproduced by canonical simple stellar populations. We also performed a structural analysis on all the clusters and found that a large core radius is not a requisite for a cluster to exhibit an eMSTO.

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Section: Introductionmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Extended main sequence turn-offs in low mass intermediate-age clusters

Piatti

Bastian

2016

A&A

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“…Then the extent of the MSTO decreases again. Such a behavior is to be expected if stellar rotation causes the spread in the MSTO (Brandt & Huang 2015a;Niederhofer et al 2015b). However, there are two outliers to this relation, NGC 1795 at 1.4 Gyr and IC 2146 at 1.9 Gyr, which both have a compact MSTO structure.…”

Section: Correlations With Agementioning

confidence: 87%

“…Bastian & Silva-Villa (2013) and Niederhofer et al (2015a) found no evidence for age spreads comparable in duration to that suggested for the intermediate-age clusters in a sample of 14 young massive LMC clusters. There could be some spreads present in the young clusters (the case of NGC 1856 will be discussed in more detail below), however these spreads would be much smaller that those inferred for the intermediate-age clusters, and the spread is a function of cluster age (Niederhofer et al 2015b).…”

Section: Other Considerations On Age Spreads Within Clustersmentioning

confidence: 99%

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Controversial age spreads from the main sequence turn-off and red clump in intermediate-age clusters in the LMC

Niederhofer

Bastian

Kozhurina-Platais

et al. 2016

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Most star clusters at an intermediate age (1−2 Gyr) in the Large and Small Magellanic Clouds show a puzzling feature in their color−magnitude diagrams (CMD) that is not in agreement with a simple stellar population. The main sequence turn-off of these clusters is much broader than expected from photometric uncertainties. One interpretation of this feature is that age spreads of the order of 200−500 Myr exist within individual clusters, although this interpretation is highly debated. Such large age spreads should affect other parts of the CMD, which are sensitive to age, as well. In this study, we analyze the CMDs of a sample of 12 intermediateage clusters in the Large Magellanic Cloud that all show an extended turn-off using archival optical data taken with the Hubble Space Telescope. We fit the star formation history of the turn-off region and the red clump region independently. We find that in most cases, the age spreads inferred from the red clumps are smaller than those that result from the turn-off region. However, the age ranges that result from the red clump region are broader than expected for a single age. Only two out of 12 clusters in our sample show a red clump which seems to be consistent with a single age. As our results are ambiguous, by fitting the star formation histories to the red clump regions, we cannot ultimately tell if the extended main sequence turn-off feature is the result of an age spread or not. However, we do find that the width of the extended main sequence turn-off feature is correlated with the age of the clusters in a way which would be unexplained in the so-called age spread interpretation, but which may be expected if stellar rotation is the cause of the spread at the turn-off.

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Impact of rotation on stellar models

et al. 2016

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After a brief recall of the main impacts of stellar rotation on the structure and the evolution of stars, four topics are addressed: 1) the links between magnetic fields and rotation; 2) the impact of rotation on the age determination of clusters; 3) the exchanges of angular momentum between the orbit of a planet and the star due to tides; 4) the impact of rotation on the early chemical evolution of the Milky Way and the origin of the Carbon-Enhanced-Metal-Poor stars.Comment: 5 pages, 2 figures, To appear in Astronomische Nachrichten, special issue "Reconstruction the Milky Way's History: Spectroscopic surveys, Asteroseismology and Chemo-dynamical models", Guest Editors C. Chiappini, J. Montalban, and M. Steffen, AN 2016 (in press

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Apparent age spreads in clusters and the role of stellar rotation

Cited by 91 publications

References 49 publications

Extended main sequence turn-offs in low mass intermediate-age clusters

Extended main sequence turn-offs in low mass intermediate-age clusters

Controversial age spreads from the main sequence turn-off and red clump in intermediate-age clusters in the LMC

Impact of rotation on stellar models

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