Observations of extreme horizontal branch stars in the globular cluster M13

我们将使用卡拉阿尔托天文台的3.5米望远镜对球状星团M13中的极端水平分支(EHB)恒星进行光谱观测。光谱对于得出大气参数是最重要的，而大气参数反过来又允许描述水平分支(HB)种群的特征并将其与其他星系团的属性相关联。尽管M13中的EHB恒星相对亮度较高，但它们从未在光谱学中被观测到。我们的观测将使我们能够第一眼看到它们的光谱性质，并将它们与其他球状星团中类似恒星的光谱性质进行比较。

We will conduct spectroscopic observations of extreme horizontal branch (EHB) stars in the globular cluster M13 using the 3.5m telescope at the Calar Alto Observatory. Optical spectra are most important for deriving atmospheric parameters which in turn allows to characterize the horizontal branch (HB) population and relate it to the other cluster's properties. Despite their relative brightness, EHB stars in M13 have never been observed in spectroscopy. Our observations will allow us to have a first glance at their spectroscopic properties and compare them to that of similar stars in other globular clusters.