论文标题
Galah调查的主要序列关闭星年的年龄
Ages of Main-Sequence Turn-Off Stars from the GALAH Survey
论文作者
论文摘要
主序列关闭（MSTO）恒星是银河系种群的良好示踪剂，因为可以从大气参数可靠地估计它们的年龄。根据GALAH调查，我们使用耶鲁旋转演化代码来确定2926 MSTO恒星的年龄，平均年龄不确定性$ \ sim $ 10 \％，考虑到C和O丰度的变化。由于C和O的丰度，与使用太阳金属混合的结果相比，由于c和o的丰度，由于c和o的丰度，与$ \ sim $ 10 \％的年龄相比，全球转移到$ \ sim $ 0.5 Gyr。 \ mbox {[Fe/h] $ \ sim $ 0.3-0.5}或\ mbox {[o/fe]〜$ \ leq $〜-0.25}的星星中，许多人的年龄差异〜$ \ geq $ 〜20 \％，甚至达到36 \％。年龄金属关系似乎可能存在两个不同的序列：年轻的恒星序列，年龄大多是$ <$ 7的gyr，以及一个相对较老的恒星序列，年龄大部分$> $ 7 gyr，重叠为5 gyr $ \ leq $ \ leq $〜$〜$〜$ \ $ \ $ \ $ \ leq $ 7 gyr。此外，丰度与年龄比的趋势显示了两个相应的序列，尤其是在[O/Fe]年龄平面中。我们还发现[Y/mg]是磁盘种群中的一个很好的化学时钟。年轻的序列和旧序列无法根据化学或运动学分离，因此恒星年龄是区分我们样品中这两个序列的重要参数。
Main sequence turn-off (MSTO) stars are good tracers of Galactic populations since their ages can be reliably estimated from atmospheric parameters. Based on the GALAH survey, we use the Yale Rotation Evolution Code to determine ages of 2926 MSTO stars with mean age uncertainty $\sim$10\% considering the variation of C and O abundances. Ages of CO-poor stars are systematically affected by $\sim$10\% due to the C and O abundances, globally shifting to $\sim$0.5 Gyr older compared to the results using solar metal-mixture. Of the stars with \mbox{[Fe/H] $\sim$0.3-0.5} or \mbox{[O/Fe]~$\leq$~-0.25}, many have fractional age differences~$\geq$~20\%, and even reach up to 36\%. The age-metallicity relation appears to possibly exist two distinct sequences: a young sequence of stars with age mostly $<$ 7 Gyr, and a relatively older sequence of stars with age mostly $>$ 7 Gyr, overlapping at 5 Gyr $\leq$~age~$\leq$ 7 Gyr. Moreover, the trends of abundances to age ratios show two corresponding sequences, especially in [O/Fe]-age plane. We also find that [Y/Mg] is a good chemical clock in disk populations. The young sequence and the old sequence can not be separated based on chemistry or kinematics, therefore stellar age is an important parameter to distinguish these two sequences in our sample.
