标题： 近红外表面亮度涨落与麦哲伦星团的光学颜色 显示英文标题

标题： Near-IR Surface Brightness Fluctuations and Optical Colours of Magellanic Star Clusters

摘要： 这项工作继续了我们通过与麦哲伦云星团数据的比较来校准模型表面亮度流量以研究未分辨恒星群体的努力。 我们在此提出了绝对 K_s 带涨落星等与 (V - I) 积分颜色之间的关系，使用来自 2MASS 和 DENIS 巡天以及文献中的数据。 我们将星团样本与刘等人（2002年）研究的早期型星系和螺旋星系核球样本进行了比较。 我们发现中间年龄到老年星团沿着一条线性相关曲线分布，误差范围内与由棒M_{K_s}与 (V - I) 图中星系定义的相关曲线具有相同的斜率。 虽然刘等人（2002年）的校准是在颜色范围 1.05 < (V - I_c)_0 < 1.25 内确定的，我们的校准适用于区间 -5 >= barM_{K_s} >= -9，0.3 <= (V - I) <= 1.25。 这表明，根据 Bruzual & Charlot (2003) 和 Mouhcine & Lancon (2003) 模型，星团和星系及核球中的最近一次恒星爆发形成事件构成了一个年龄序列。 同时，星系和星团之间存在轻微偏移 [在给定 (V - I) 值时，后者比前者暗约 0.7 等]，这是由于金属丰度差异约为两倍。 模型与星系数据的对比还表明，对于那些比预期更亮的 K_s 涨落星等的星系，部分可以用热脉冲 AGB 星更高的寿命来解释。 （简略版。） 显示英文摘要

摘要： This work continues our efforts to calibrate model surface brightness luminosities for the study of unresolved stellar populations, through the comparison with data of Magellanic Cloud star clusters. We present here the relation between absolute K_s-band fluctuation magnitude and (V - I) integrated colour, using data from the 2MASS and DENIS surveys, and from the literature. We compare the star cluster sample with the sample of early-type galaxies and spiral bulges studied by Liu et al. (2002). We find that intermediate-age to old clusters lie along a linear correlation with the same slope, within the errors, of that defined by the galaxies in the barM_{K_s} vs. (V - I) diagram. While the calibration by Liu et al. was determined in the colour range 1.05 < (V - I_c)_0 < 1.25, ours holds in the interval -5 >= barM_{K_s} >= -9, 0.3 <= (V - I) <= 1.25. This implies, according to Bruzual & Charlot (2003) and Mouhcine & Lancon (2003) models, that the star clusters and the latest star formation bursts in the galaxies and bulges constitute an age sequence. At the same time, there is a slight offset between the galaxies and the star clusters [the latter are ~ 0.7 mag fainter than the former at a given value of (V - I)], caused by the difference in metallicity of roughly a factor of two. The confrontation between models and galaxy data also suggests that galaxies with K_s fluctuation magnitudes that are brighter than predicted, given their (V - I) colour, might be explained in part by longer lifetimes of TP-AGB stars. (Abridged version.)