Chemical element transport in stellar evolution models

Salaris, Maurizio; Cassisi, S.

doi:10.1098/rsos.170192

Cited by 101 publications

(92 citation statements)

References 214 publications

(458 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We assume this to be the case in our models, such that the REM is only of macroscopic origin. Unfortunately, the overall profile of neither the CBM nor the REM is well understood, as it cannot be derived from first principles (e.g., Salaris & Cassisi 2017, for a review). Recently, however, asteroseismic modelling of intermediate-mass stars has been able to probe the level of this CMB+REM mixing profile from g-mode period-spacing patterns and their deviations from uniformity (e.g., Moravveji et al 2015Moravveji et al , 2016Schmid & Aerts 2016;Mombarg et al 2019).…”

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

View full text Add to dashboard Cite

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.

show abstract

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

View full text Add to dashboard Cite

show abstract

“…From a physical standpoint, it is important to highlight that regions of partial ionisation of chemical elements are regions of large variations of ionic charges and that electric charges are among the main ingredients of the generation of magnetic fields. It is known that the effect of internal magnetic fields is tightly related to the redistribution of angular momentum in the stellar interiors, which in turn, cannot be separated from the internal chemical element transport (e.g., Salaris & Cassisi 2017). Among the physical processes that act to redistribute angular momentum throughout the interior of the star are several hydrodynamical instabilities (e.g., Palacios 2013), such as, for example, the Tayler-Spruit magneto-rotational instability (Tayler 1973;Spruit 2002).…”

Section: Discussionmentioning

confidence: 99%

The partial ionization zone of heavy elements in F-stars: a study on how it correlates with rotation

Brito

Lopes

2019

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We study the relation between the internal structures of 10 benchmark main-sequence F-stars and their rotational properties. Stellar rotation of main-sequence F-type stars can be characterised by two distinct rotational regimes. Early-type F-stars are usually rapid rotators with periods typically below 10 days, whereas later-type F-stars have longer rotation periods. Specifically, and since the two rotational regimes are tightly connected to the effective temperatures of the stars, we investigate in detail the characteristics of the partial ionisation zones in the outer convective envelopes of these stars, which in turn, depend on the internal temperature profiles.Our study shows that the two rotational regimes might be distinguished by the relative locations of the partial ionisation region of heavy elements and the base of the convective zone. Since in all these stars is expected a dynamo-driven magnetic field where the shear layer between convective and radiative zones (tachocline) plays an important role, this result suggests that the magnetic field may be related to the combined properties of convection and ionisation.

show abstract

“…Finally, the diffusive effect process is not taken into account in our analysis on the He abundance because the hot massive stars are characterized by a strong mass loss and rotational mixing, which tend to limit or completely erase the effect of diffusion (Salaris & Cassisi 2017).…”

Section: Nlte Effectmentioning

confidence: 99%

MUSE Observations of NGC330 in the Small Magellanic Cloud: Helium Abundance of Bright Main-sequence Stars*

Carini

Biazzo

Brocato

et al. 2020

View full text Add to dashboard Cite

We present observations of the most bright main sequence stars in the Small Magellanic Cloud stellar cluster NGC 330 obtained with the integral field spectrograph MUSE@VLT. The use of this valuable instrument allows us to study both photometric and spectroscopic properties of stellar populations of this young star cluster.The photometric data provide us a precise color magnitude diagram, which seems to support the presence of two stellar populations of ages of ≈ 18 Myr and ≈ 30 Myr assuming a metallicity of Z = 0.002.Thanks to the spectroscopic data, we derive helium abundance of 10 main sequence stars within the effective radius R eff = 20 of NGC 330, thus leading to an estimation of (He) = 10.93 ± 0.05 (1σ).The helium elemental abundances of stars likely belonging to the two possible stellar populations, do not show differences or dichotomy within the uncertainties. Thus, our results suggest that the two stellar populations of NGC 330, if they exist, share similar original He abundances.If we consider stellar rotation velocity in our analysis, a coeval (30 Myr) stellar population, experiencing different values of rotation, cannot be excluded. In this case, the mean helium abundance < (He) > rot obtained in our analysis is 11.00 ± 0.05 dex. We also verified that possible NLTE effects cannot be identified with our analysis because of the spectral resolution and they are within our derived abundance He uncertainties.Moreover, the analysis of the He abundance as a function of the distance from the cluster center of the observed stars do not show any correlation.

show abstract

Chemical element transport in stellar evolution models

Cited by 101 publications

References 214 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

The partial ionization zone of heavy elements in F-stars: a study on how it correlates with rotation

MUSE Observations of NGC330 in the Small Magellanic Cloud: Helium Abundance of Bright Main-sequence Stars*

Contact Info

Product

Resources

About