Characterisation of FG-type stars with an improved transport of chemical elements
arxiv(2024)
摘要
Context. The modelling of chemical transport mechanisms is crucial for
accurate stellar characterizations. Atomic diffusion is one of these processes
and it is commonly included in stellar models. However, it is usually neglected
for F-type or more massive stars because it produces surface abundance
variations that are unrealistic. Additional mechanisms to counteract atomic
diffusion must therefore be considered. It has been demonstrated that turbulent
mixing can prevent the surface abundance over-variations, and can also be
calibrated to mimic the effects of radiative accelerations on iron. Aims. We
aim to evaluate the effect of a calibrated turbulent mixing on the
characterisation of a sample of F-type stars, and how the estimates compare
with those obtained when the chemical transport mechanisms are neglected.
Methods. We selected stars from two samples - one from the Kepler LEGACY sample
and the other from a sample of Kepler planet-hosting stars. We inferred their
stellar properties using two grids. The first grid considers atomic diffusion
only in models that do not show chemical over-variations at the stellar
surface. The second grid includes atomic diffusion in all the stellar models
and the calibrated turbulent mixing to avoid unrealistic surface abundances.
Results. Comparing the derived results from the two grids, we found that the
results for the more massive stars in our sample will have higher dispersion in
the inferred values of mass, radius and age, due to the absence of atomic
diffusion in one of the grids. This can lead to relative uncertainties for
individual stars of up to 5
Conclusions. This work shows that a proper modelling of the microscopic
transport processes is key for an accurate estimation of their fundamental
properties not only for G-type stars, but also for F-type stars.
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