The effect of diffusion on the red giant luminosity function ‘bump’
The effect of diffusion on the red giant luminosity function ‘bump’
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DOI：
10.1093/mnras/290.3.515
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发表时间：
1997-06
影响因子：
4.8
通讯作者：
S. Cassisi;S. Degl'innocenti;M. Salaris
中科院分区：
文献类型：
--
作者：
S. Cassisi;S. Degl'innocenti;M. Salaris
本文研究了在粒子数II恒星模型中，氦和重元素的微观扩散对红巨星分支光度函数凸起位置的影响。为此，计算了最新的演化模型，该模型考虑了从主序列到零年代水平分支的扩散。对一个银河系球状星团样本所收集的RGB凸起和ZAHB之间的观测光度差，与采用正则模型和扩散模型得到的相应理论值进行了比较。我们发现，扩散的影响，即使稍微改善了观测和理论之间的一致性，对于观测的不确定性来说是可以忽略不计的。在任何情况下，在有扩散和无扩散的模型中的理论预测似乎与观测结果在估计误差范围内是一致的。因此，规范模型仍然可以安全地被采用，至少在获得更准确的观测数据之前是这样。
This paper investigates the effect of microscopic diffusion of helium and heavy elements on the location of the Red Giant Branch Luminosity Function Bump in Population II stellar models. To this aim updated evolutionary models taking into account diffusion from the Main Sequence until the Zero Age Horizontal Branch have been computed. The observational luminosity difference between the RGB bump and the ZAHB, as collected for a sample of galactic globular clusters, has been compared with the corresponding theoretical values obtained by adopting both canonical and diffusive models. We find that the effect of diffusion, even if slightly improving the agreement between observations and theory, is negligible with respect to the observational uncertainties. In any case the theoretical predictions in models with and without diffusion appear in agreement with the observational results within the estimated errors. Thus canonical models can be still safely adopted, at least until much more accurate observational data will be available.