恒星年龄的不确定性分析

The Uncertainties of Stellar Ages

选取已确定恒星年龄和化学丰度的3个观测样本,统一用Yonsei-Yale等年龄线确定了恒星年龄,分析了恒星的绝对星等MV、有效温度Teff、金属丰度[Fe/H]和α元素相对丰度[α/Fe]等4个输入参数的误差对恒星年龄的影响,最后利用误差理论分析和估算了各种因素对恒星年龄不确定性的综合影响.结果表明,Teff,[Fe/H],[α/Fe]对恒星年龄的影响是系统性的,而且其影响程度依次递减;而MV对恒星年龄的影响是随机的,其影响程度是最弱的.误差分析表明,如果取Teff,MV,[Fe/H],[α/Fe]的典型观测误差分别为100 K,0.1 mag,0.1 dex,0.1 dex,则由此造成的恒星年龄的平均标准偏差为3.2 Ga.

Three observational samples selected in which the stellar ages and chemical abundances have been presented in detail. The ages of these sample stars were recomputed, using Yonsei-Yale isochrones. Then the uncetainties of stellar ages resulted from stellar absolute magnitude My, effective temperature Telf, metallicity [ Fe/ H] and the a-elements relative abundances [α/Fe] were analysed,respectively. Using error analysis theory,a total uncertainty of stellar ages was estimated, considering all the influence of indivadual factors. The results show that the influences from Telf, [Fe/H] and [α/Fe] to stellar ages are systematic,and their influence extent is gradually decreasing correspondingly. However the influence from Mv to stellar age is random and its influence extent is the weakest among the four input parameters. It is showed that an average standard deviation of 3.2 Ga for stellar ages corresponding to the typical errors △Teff = 100 K, Mv = 0.1 mag, [ Fe/H] = 0.1 dex and [ α/Fe] = 0.1 dex.