标题： RR Lyrae变星距离尺度 显示英文标题

标题： The RR Lyrae Distance Scale

摘要： 我们回顾了七种在依巴谷任务及其他近期发展背景下测量RR天琴座变星的绝对星等M_V的方法。 我们着重于识别可能的系统误差，并根据这些方法对系统误差的免疫程度进行排序。 对于三种最可靠的方法，统计视差、三角视差和星团运动学，我们发现M_V（在[Fe/H] = -1.6时）分别为0.77 +/- 0.13、0.71 +/- 0.15、0.67 +/- 0.10。 这些方法一致地聚集在0.71 +/- 0.07附近。 我们发现，Baade-Wesselink方法和理论模型都由于温度尺度和输入物理参数的系统不确定性而给出一个较宽的可能值范围（0.45-0.70和0.45-0.65）。 主序线拟合给出一个更亮的M_V = 0.45 +/- 0.04，但这可能是由于星团巨星和校准亚矮星金属丰度尺度之间的差异。 白矮星冷却序列拟合给出0.67 +/- 0.13，这在理论上非常可靠，但目前仍太新，无法完全测试其系统误差。 如果将三种最可靠的方法与Walker对6个LMC星团的平均测量结果相结合，V_{0,LMC} = 18.98 +/- 0.03在[Fe/H] = -1.9时，那么mu_{LMC} = 18.33 +/- 0.08。 显示英文摘要

摘要： We review seven methods of measuring the absolute magnitude M_V of RR Lyrae stars in light of the Hipparcos mission and other recent developments. We focus on identifying possible systematic errors and rank the methods by relative immunity to such errors. For the three most robust methods, statistical parallax, trigonometric parallax, and cluster kinematics, we find M_V (at [Fe/H] = -1.6) of 0.77 +/- 0.13, 0.71 +/- 0.15, 0.67 +/- 0.10. These methods cluster consistently around 0.71 +/- 0.07. We find that Baade-Wesselink and theoretical models both yield a broad range of possible values (0.45-0.70 and 0.45-0.65) due to systematic uncertainties in the temperature scale and input physics. Main-sequence fitting gives a much brighter M_V = 0.45 +/- 0.04 but this may be due to a difference in the metallicity scales of the cluster giants and the calibrating subdwarfs. White-dwarf cooling-sequence fitting gives 0.67 +/- 0.13 and is potentially very robust, but at present is too new to be fully tested for systematics. If the three most robust methods are combined with Walker's mean measurement for 6 LMC clusters, V_{0,LMC} = 18.98 +/- 0.03 at [Fe/H] = -1.9, then mu_{LMC} = 18.33 +/- 0.08.