Isochrone-cloud fitting of the extended Main-Sequence Turn-Off of young clusters

Abstract

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. 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. 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 NGC 1850 and NGC 884, 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 pulsation properties. 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 pulsation 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 vsini and a few pulsation frequencies show no correlation between these properties and the core masses of the stars that set the cluster age. 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.

11 pages, 8 figures, 1 table, NGC 1850, NGC 884, accepted for publication in A&A

References in corpus (33)

• Modules for Experiments in Stellar Astrophysics (MESA)
• Modules for Experiments in Stellar Astrophysics (MESA): Pulsating Variable Stars, Rotation, Convective Boundaries, and Energy Conservation
• Slowing the Spins of Stellar Cores
• Rotational mixing in massive binaries: detached short-period systems
• CLES, Code Liegeois d'Evolution Stellaire
• Asteroseismic measurement of surface-to-core rotation in a main sequence A star, KIC 11145123
• The interior rotation of a sample of gamma Doradus stars from ensemble modelling of their gravity mode period spacings
• Angular momentum transport by heat-driven g-modes in slowly pulsating B stars
• Multiple stellar populations in three rich Large Magellanic Cloud star clusters
• Asteroseismic measurement of slow, nearly-uniform surface-to-core rotation in the main sequence F star KIC 9244992
• Low-frequency gravity waves in blue supergiants revealed by high-precision space photometry
• Signatures of internal rotation discovered in the Kepler data of five slowly pulsating B stars
• An asteroseismic study of the beta Cephei star theta Ophiuchi: constraints on global stellar parameters and core overshooting
• Gravito-inertial and pressure modes detected in the B3 IV CoRoT target HD 43317
• Populations of rotating stars III. SYCLIST, the new Geneva Population Synthesis code
• Instability strips of SPB and beta Cephei stars: the effect of the updated OP opacities and of the metal mixture
• On the Chemical Mixing Induced by Internal Gravity Waves (IGW)
• Asteroseismic masses, ages, and core properties of $\gamma$ Doradus stars using gravito-inertial dipole modes and spectroscopy
• The dependence of convective core overshooting on stellar mass: reality check, and additional evidence
• The interior angular momentum of core hydrogen burning stars from gravity-mode oscillations
• NGC 1866: First Spectroscopic Detection of Fast Rotating Stars in a Young LMC Cluster
• A high fraction of Be stars in young massive clusters: evidence for a large population of near-critically rotating stars
• Period spacings of $\gamma$ Doradus pulsators in the \textit{Kepler} field: Rossby and gravity modes in 82 stars
• Stars caught in the braking stage in young Magellanic Clouds clusters
• The young massive SMC cluster NGC 330 seen by MUSE. I. Observations and stellar content
• Extended Main Sequence Turnoffs in Intermediate-Age Star Clusters: Stellar Rotation diminishes, but does not eliminate, Age Spreads
• Extended main-sequence turnoffs in the double cluster $h$ and $\chi$ Persei: The complex role of stellar rotation
• Discrepancies in the ages of young star clusters; evidence for mergers?
• Dissecting the Extended Main Sequence Turn-off of the Young Star Cluster NGC1850
• Disappearance of the extended main sequence turn-off in intermediate age clusters as a consequence of magnetic braking
• Critical angular velocity and anisotropic mass loss of rotating stars with radiation-driven winds
• The effects of the overshooting of the convective core on main-sequence turnoffs of young- and intermediate-age star clusters
• Metallicity estimates of young clusters in the Magellanic Clouds from Stromgren photometry of supergiant stars

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