论文标题
CA II三重三重度光度依赖性的全面校准
Panchromatic calibration of Ca II triplet luminosity dependence
论文作者
论文摘要
（删节）上下文。 Ca II三重态（CAT）线的线强度是测量来自亮红色巨星单个恒星光谱的金属性的代理。在将它们转换为金属率之前，从线的等效宽度（eW）中去除重力，温度和发光度的幅度（替代重力，温度和发光度）是强制性步骤。数十年来使用的工作经验程序是使用相对水平分支水平的相对幅度。目标。 v滤波器广泛地用作参考幅度，尽管其中一些作品使用了不同的过滤器（例如，i和ks）。在这项工作中，我们使用DECAM和GMOS的GRIZ过滤器，GAIA，MCPS的BVI过滤器，来自VIRCAM的YJKS滤波器的BVI过滤器研究了CAT校准的依赖性。我们用作样品原始分析中使用的参考fors2 V滤波器。方法。来自具有已知金属性和可用猫等效宽度的簇的红色巨星被用作参考。公共光度表目录取自Smash DR2，VMC，Gaia，MCPS调查以及Viscacha-GMOS数据，用于选择小型麦哲伦云簇。使用两条和三行拟合斜率，适用于大多数金属度尺度。结果。使用本工作中分析的任何过滤器的线性关系很好地描述了CAT EWS的幅度依赖性。斜率随滤波器的波长而增加。零点（又称等效宽度），即金属性指标，保持不变。结论。如果使用相同的线条函数与相同的带通和连续区域一起使用，并且总EW来自相同数量的线（2或3），则不管使用的过滤器所使用的过滤器，还原的EW是相同的。因此，任何过滤器可用于将猫等效宽度转换为给定猫校准的金属性。
(ABRIDGED) Context. The line strength of the Ca II triplet (CaT) lines are a proxy to measure metallicity from individual stellar spectra of bright red giant stars. It is a mandatory step to remove the magnitude (proxy for gravity, temperature and luminosity) dependence from the equivalent width (EW) of the lines before converting them into metallicities. The working empirical procedure used for decades is to use the relative magnitude with respect to the horizontal branch level. Aims. The V filter is broadly adopted as the reference magnitude, although a few works have used different filters (I and Ks, for example). In this work we investigate the dependence of the CaT calibration using griz filters from the DECam and the GMOS, G from Gaia, BVI filters from the MCPS, YJKs filters from VIRCAM. We use as a reference FORS2 V filter used in the original analysis of the sample. Methods. Red giant stars from clusters with known metallicity and available CaT equivalent widths are used as reference. Public photometric catalogues are taken from SMASH DR2, VMC, Gaia, MCPS surveys plus VISCACHA-GMOS data, for a selection of Small Magellanic Cloud clusters. The slopes are fitted using two and three lines to be applicable to most of the metallicity scales. Results. The magnitude dependence of the CaT EWs is well described by a linear relation using any filter analysed in this work. The slope increases with wavelength of the filters. The zero point (a.k.a. reduced equivalent width), that is the metallicity indicator, remains the same. Conclusions. If the same line profile function is used with the same bandpasses and continuum regions, and the total EW comes from the same number of lines (2 or 3), then the reduced EW is the same regardless the filter used. Therefore, any filter can be used to convert the CaT equivalent widths into metallicity for a given CaT calibration.
