论文标题
球状簇NGC 7006中可变星人群的详细分析
Detailed analysis of the variable star population in the globular cluster NGC 7006
论文作者
论文摘要
NGC 7006的五年CCD光度\ EMPH {VI}时间序列用于对已知可变星人群进行详细分析。在此过程中，我们纠正了不一致的分类，天空坐标并发现了十个新的群集成员变量。具有$ e（b-v）= 0.08 \ pm0.05 $的独立红色估计。使用RR Lyrae光曲线和良好校准的傅立叶分解，群集平均金属性和距离[Fe/H] $ _ {\ rm zw} = -1.53 \ pm0.15 $和$ 41.2 \ $ 41.2 \ pm1.4 $ kpc估计，基于cluster成员Rrrab Sarts的扩展样品。使用$ GAIA $ -DR3数据，我们进行了广泛的成员资格分析，该分析可导致干净的颜色 - 磁性图，从而识别可能是现场恒星的变量，并考虑了水平分支（HB）中变量分布的考虑。讨论了双重模式RR Lyre和三CW星。争论了Hb蓝色尾巴的前体的CW恒星的起源（$ \ sim 0.06 \ pm 0.01 m _ {\ odot} $）信封是有争议的。我们的模型表明，RR Lyrae恒星的主要序列前身的质量为0.82-0.85 $ M _ {\ odot} $，在红色巨型分支事件中损失了约25-35％的质量，然后在HB中安顿下来，后来大约12-13.5 Gyrs。
A five year CCD photometric \emph{VI} time-series of NGC 7006 is employed to perform a detailed analysis of the known population of variable stars. In the process we have corrected inconsistent classifications, sky coordinates and found ten new cluster member variables. An independent reddening estimate with a value $E(B-V)=0.08\pm0.05$ is made. Using Fourier decompositions of RR Lyrae light curves and well established calibrations, the cluster mean metallicity and distance [Fe/H]$_{\rm ZW}= -1.53\pm0.15$ and $41.2\pm1.4$ kpc are estimated based on an extended sample of cluster member RRab stars. Using the $Gaia$-DR3 data we performed an extensive membership analysis which leads to a clean Colour-Magnitude diagram, and hence to the identification of variables that are likely field stars, and to considerations on the variables distribution in the Horizontal Branch (HB). A double mode RR Lyrae and three CW star are discussed. The origin of CW stars from precursors in the blue tail of the HB with very thin ($\sim 0.06 \pm 0.01 M_{\odot}$) envelopes is argued. Our models indicate that the Main Sequence predecessor of RR Lyrae stars had a mass of 0.82-0.85 $M_{\odot}$ and lost about 25-35\% of its mass during the red giant branch events before settling in the HB some 12-13.5 Gyrs later.
