发表机构
Instituto de Astronomía, Universidad Nacional Autónoma de México（墨西哥国立自治大学天文学研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过VI波段CCD测光分析NGC 6426的色-星等图与变星，采用傅里叶分解、校准关系及贝叶斯方法，确定了该星团的金属丰度、距离、年龄等关键参数。
AI 中文摘要
我们给出了球状星团NGC 6426的新VI波段CCD测光结果。讨论了视场内所有点源，尤其是所有变星的成员资格状态，包括4颗新近探测到的变星。确认了变星V3和V9的双模式性质，并计算了它们的周期；报告了星团成员异常造父变星V17的存在。仅采用可能的成员星，我们生成了经过差分消光改正的去污染色-星等图（CMD），该图可与理论预测进行比较，并用于研究变星的分布。通过天琴座RR型变星V波段光曲线的傅里叶分解以及周期-星等-金属丰度关系的I波段校准，计算了星团的平均金属丰度和距离。此外，使用Dartmouth恒星演化数据库（DSED）的理论等时线与深场哈勃空间望远镜（HST）CMD进行贝叶斯方法比较，为我们提供了距离模数、金属丰度、色余和星团年龄的独立估计值。
英文摘要
We present new VI CCD photometry of the globular cluster NGC 6426. The membership status of all point sources and, in particular, of all the variables in the field of view is discussed, including four recently detected variables. The double mode nature of variables V3 and V9 is confirmed and their periods are calculated. The presence of a cluster member anomalous Cepheid (V17) is reported. Employing only likely members we produce a decontaminated colour-magnitude diagram (CMD) differentially dereddened, which enables us to compare it with theoretical predictions and to study the variable stars distribution. The mean cluster metallicity and distance were calculated via the RR Lyrae V-band light curve Fourier decomposition and an I-band calibration of the Period-Magnitude-Metallicity relation. Further, a comparison using a Bayesian approach between theoretical isochrones of Dartmouth Stellar Evolution Database (DSED), with a deep HST CMD, gave us independent estimates of distance modulus, metallicity, colour excess, and cluster age.
Comments16 pages, 8 Figures, 6 Tables. Accepted for publication by Revista Mexicana de Astronomia y Astrofisica
