标题： 银河盘星的铷丰度 显示英文标题

标题： Rubidium abundances of galactic disk stars

摘要： 通过将光谱拟合法应用于铷（Rubidium）I原子的7800埃谱线，对属于银河盘星族的大约500颗晚型矮星以及巨星（包括毕宿五星团中的恒星）进行了铷丰度的光谱测定，旨在研究盘星族中[Rb/Fe]比值随金属丰度[-0.6<[Fe/H]<+0.3]的变化行为。 对毕宿五矮星的铷丰度结果进行检查后发现，在温度>5500K时它们显示出系统性的有效温度依赖性趋势；这意味着中G至F型恒星（包括太阳）的结果可能不可靠（即或多或少被高估），这可能是由于经典模型大气中表面对流处理不完善所致。 因此，决定仅限于有效温度Teff<5500K的晚G和K型恒星，并采用太阳系（陨石）的铷丰度作为参考值。 对于场星（field stars）中的矮星和巨星得出的[Rb/Fe]与[Fe/H]关系一致，显示随着[Fe/H]降低，[Rb/Fe]逐渐增加（在太阳金属丰度附近，其梯度约为~−0.4），这与化学演化模型的理论预测相吻合。 因此，本研究未能证实最近报道的M型矮星（-0.3<[Fe/H]<+0.3）中[Rb/Fe]比值的异常行为（趋向亚太阳但向超太阳金属丰度急剧上升）。 显示英文摘要

摘要： Spectroscopic determinations of Rubidium abundances were conducted by applying the spectrum fitting method to the Rb I 7800 line for an extensive sample of ~500 late-type dwarfs as well as giants (including Hyades cluster stars) belonging to the galactic disk population, with an aim of establishing the behaviour of [Rb/Fe] ratio for disk stars in the metallicity range of -0.6<[Fe/H]<+0.3. An inspection of the resulting Rb abundances for Hyades dwarfs revealed that they show a systematic Teff-dependent trend at >5500K; this means that the results for mid-G to F stars (including the Sun) are not reliable (i.e., more or less overestimated), which might be due to some imperfect treatment of surface convection in classical model atmospheres. As such, it was decided to confine only to late-G and K stars at Teff<5500K and adopt the solar-system (meteoritic) value as the reference Rb abundance. The [Rb/Fe] vs.[Fe/H] relations derived for field dwarfs and giants turned out to be consistent with each other, showing a gradual increase of [Rb/Fe] with a decrease in [Fe/H] (with d[Rb/Fe]/d[Fe/H] gradient of ~-0.4 around the solar metallicity), which is favourably compared with the theoretical prediction of chemical evolution models. Accordingly, this study could not confirm the anomalous behaviour of [Rb/Fe] ratio (tending to be subsolar but steeply increasing toward supersolar metallicity) recently reported for M dwarf stars of -0.3<[Fe/H]<+0.3.