论文标题
AMFM恒星中扫描量的演变的建模
Modelling of the scandium abundance evolution in AmFm stars
论文作者
论文摘要
Scandium是AM星现象的关键要素，因为其表面不足是表征此类恒星的标准之一。得益于该元素的一组足够完整的理论原子数据的可用性，现在可以计算出可靠的辐射加速度，从而可以对其在原子扩散的作用下进行建模。我们在混合过程或质量损失方面探讨了所需的条件，以使我们的模型重现AM恒星中SC的表面丰度。使用Toulouse-Geneva Evolution代码计算模型，该代码使用参数单值参数方法来计算辐射加速度。使用来自3D流体动力学模拟的处方，包括指法混合。还考虑了其他参数依赖性的湍流混合过程。还实施了全球群众损失。当不考虑质量损失时，观察到的SC的丰富性会支持其浅层层完全混合到铁累积区的模型，尽管其他混合处方也能够重现此处介绍的最大模型的观测值（$ 2.0 M_ \ odot $）。包括质量损失的模型在$ [10^{ - 13}; 10^{ - 14}] M_ \ odot $/yr的范围内与某些观察值兼容，而其他观察结果表明质量损失率可能较低。 SC建模带来的约束与使用其他化学元素得出的限制是一致的。
Scandium is a key element of the Am star phenomenon since its surface under-abundance is one of the criteria that characterise such stars. Thanks to the availability of a sufficiently complete set of theoretical atomic data for this element, reliable radiative accelerations for Sc can now be computed, which allows its behaviour under the action of atomic diffusion to be modelled. We explore the required conditions, in terms of mixing processes or mass loss, for our models to reproduce the observed surface abundances of Sc in Am stars. The models are computed with the Toulouse-Geneva evolution code, which uses the parametric single-valued parameter method for the calculation of radiative accelerations. Fingering mixing is included, using a prescription that comes from 3D hydrodynamical simulations. Other parameter-dependent turbulent mixing processes are also considered. A global mass loss is also implemented. When no mass loss is considered, the observed abundances of Sc are rather in favour of the models whose superficial layers are fully mixed down to the iron accumulation zone, although other mixing prescriptions are also able to reproduce the observations for the most massive model presented here ($2.0 M_\odot$). The models including mass loss with rates in the range of $[10^{-13};10^{-14}] M_\odot$/yr are compatible with some of the observations, while other observations suggest that the mass-loss rate could be lower. The constraints brought by the modelling of Sc are consistent with those derived using other chemical elements.
