论文标题
关于RR Lyrae和II型头孢虫之间的分离及其对距离确定的重要性：$ω$ CEN的情况
On the separation between RR Lyrae and Type II Cepheids and their importance for distance determination: the case of $ω$ Cen
论文作者
论文摘要
基于其周期的RR Lyrae（RRL）和II型头孢菌（T2C）变量之间的分离是有争议的。两种类型的可变恒星都是距离指标，我们旨在促进将T2C作为与RRL协同作用的距离指标的使用。我们采用了\ wcen〜的新的和现有的光学和近红外（NIR）光度法，以研究几个诊断（颜色 - 磁性图，贝利图，光曲线的傅立叶分解，振幅比率），以进行经验分离。我们发现，1天的经典阈值不是通用的，也不决定进化阶段：V92的周期为1.3天，但可能仍处于其核心氦气燃烧阶段，这是典型的RRLS。我们还得出了NIR时期luminosity的关系，并发现距离模量为13.65 $ \ pm $ 0.07（err。）$ \ pm $ 0.01（$σ$）mag，与最近的文献一致。我们还发现，RRL和T2C在NIR中遵守相同的PL关系。这种等效性使有机会采用RRLS+T2C作为替代经典头孢虫的替代品来校准外乳缘距离尺度。
The separation between RR Lyrae (RRLs) and Type II Cepheid (T2Cs) variables based on their period is debated. Both types of variable stars are distance indicators and we aim to promote the use of T2Cs as distance indicators in synergy with RRLs. We adopted new and existing optical and Near-Infrared (NIR) photometry of \wcen~to investigate several diagnostics (colour-magnitude diagram, Bailey diagram, Fourier decomposition of the light curve, amplitude ratios) for their empirical separation. We found that the classical period threshold at 1 day is not universal and does not dictate the evolutionary stage: V92 has a period of 1.3 days but is likely to be still in its core Helium-burning phase, typical of RRLs. We also derived NIR Period-Luminosity relations and found a distance modulus of 13.65$\pm$0.07 (err.)$\pm$0.01 ($σ$) mag, in agreement with the recent literature. We also found that RRLs and T2Cs obey the same PL relations in the NIR. This equivalence gives the opportunity to adopt RRLs+T2Cs as an alternative to classical Cepheids to calibrate the extragalactic distance scale.
