NGC 1866: First Spectroscopic Detection of Fast-rotating Stars in a Young LMC Cluster

Dupree, A. K.; Dotter, Aaron; Johnson, Christian I.; Marino, A. F.; Milone, A. P.; Bailey, John I.; Crane, Jeffrey D.; Mateo, Mario; Olszewski, Edward W.

doi:10.3847/2041-8213/aa85dd

Cited by 84 publications

(81 citation statements)

References 42 publications

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“…The observed eMSTOs have been associated with fast surface rotation as revealed by spectroscopy (e.g., Dupree et al 2017;Kamann et al 2018;Marino et al 2018b;Bastian et al 2018). While some clusters with high-mass stars at the eMSTO show a correlation between Hα emission and location in the CMD (Bodensteiner et al, submitted), others such as the double cluster h and χ Persei reveal no relation between colour and rotational velocities (Li et al 2019a).…”

Section: Introductionmentioning

confidence: 99%

Isochrone-cloud fitting of the extended main-sequence turn-off of young clusters

Johnston

Aerts

Pedersen

et al. 2019

A&A

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Context. Extended main-sequence turn-offs (eMSTO) are a commonly observed property of young clusters. A global theoretical interpretation for the eMSTOs is still lacking, but stellar rotation is considered a necessary ingredient to explain the eMSTO. Aims. We aim to assess the importance of core-boundary and envelope mixing in stellar interiors for the interpretation of eMSTOs in terms of one coeval population. Methods. We construct isochrone-clouds based on interior mixing profiles of stars with a convective core calibrated from asteroseismology of isolated galactic field stars. We fit these isochrone-clouds to the measured eMSTO to estimate the age and core mass of the stars in the two young clusters NGC1850 and NGC884, assuming one coeval population and fixing the metallicity to the one measured from spectroscopy. We assess the correlations between the interior mixing properties of the cluster members and their rotational and pulsational properties. Results. We find that stellar models based on asteroseismically-calibrated interior mixing profiles lead to enhanced core masses of eMSTO stars and can explain a good fraction of the observed eMSTOs of the two considered clusters in terms of one coeval population of stars, with similar ages to those in the literature, given the large uncertainties. The rotational and pulsational properties of the stars in NGC 884 are not sufficiently well known to perform asteroseismic modelling, as it is achieved for field stars from space photometry. The stars in NGC 884 for which we have v sin i and a few pulsation frequencies show no correlation between these properties and the core masses of the stars that set the cluster age. Conclusions. Future cluster space asteroseismology may allow to interpret the values of the core masses in terms of the physical processes that cause them, based on the modelling of the interior mixing profiles for the individual member stars with suitable identified modes.

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Section: Introductionmentioning

confidence: 99%

Isochrone-cloud fitting of the extended main-sequence turn-off of young clusters

Johnston

Aerts

Pedersen

et al. 2019

A&A

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“…However, recent observations have directly linked the position of stars in the CMDs to their projected rotational velocity (v sin i) values (e.g. Dupree et al 2017;Kamann et al 2018b;Bastian et al 2018;Marino et al 2018).…”

Section: Introductionmentioning

confidence: 99%

How stellar rotation shapes the colour−magnitude diagram of the massive intermediate-age star cluster NGC 1846

Kamann

Bastian

Gossage

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We present a detailed study of stellar rotation in the massive 1.5 Gyr old cluster NGC 1846 in the Large Magellanic Cloud. Similar to other clusters at this age, NGC 1846 shows an extended main sequence turn-off (eMSTO), and previous photometric studies have suggested it could be bimodal. In this study, we use MUSE integral-field spectroscopy to measure the projected rotational velocities (v sin i) of around 1 400 stars across the eMSTO and along the upper main sequence of NGC 1846. We measure v sin i values up to ∼ 250 km s −1 and find a clear relation between the v sin i of a star and its location across the eMSTO. Closer inspection of the distribution of rotation rates reveals evidence for a bimodal distribution, with the fast rotators centred around v sin i = 140 km s −1 and the slow rotators centred around v sin i = 60 km s −1 . We further observe a lack of fast rotating stars along the photometric binary sequence of NGC 1846, confirming results from the field that suggest that tidal interactions in binary systems can spin down stars. However, we do not detect a significant difference in the binary fractions of the fast and slowly rotating sub-populations. Finally, we report on the serendipitous discovery of a planetary nebula associated with NGC 1846.

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“…The first spectroscopy (Dupree et al 2017) of turn-off stars in a young (200 Myr) LMC cluster, NGC 1866, revealed that rapidly rotating stars are indeed present (Figure 1). The Hα line appears in emission centered on the stellar radial velocity, and is typical of that found in Be stars.…”

Section: The Color-magnitude Diagrammentioning

confidence: 99%

“…Two stars exhibiting substantial Hα variability. (Identifications inDupree et al 2017). The broken lines mark the full width at half power of the response of the F656N filter on HST/WFC3.…”

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confidence: 99%

Spectroscopy of LMC cluster stars

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NGC 1866: First Spectroscopic Detection of Fast-rotating Stars in a Young LMC Cluster

Cited by 84 publications

References 42 publications

Isochrone-cloud fitting of the extended main-sequence turn-off of young clusters

Isochrone-cloud fitting of the extended main-sequence turn-off of young clusters

How stellar rotation shapes the colour−magnitude diagram of the massive intermediate-age star cluster NGC 1846

Spectroscopy of LMC cluster stars

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