Subdwarf studies. II - Abundances and kinematics from medium resolution spectra. III - The halo metallicity distribution
Subdwarf studies. II - Abundances and kinematics from medium resolution spectra. III - The halo metallicity distribution
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亚矮人研究。
DOI：
10.1086/115811
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
J. Norris
中科院分区：
文献类型：
--
作者：
S. Ryan;J. Norris
以前被发现有紫外线过剩的恒星在CaII K线区域以1-A的分辨率被观测到。将这些数据与其他样本进行比较，并与涉及单组分晕的蒙特卡罗模拟进行比较，得到了晕速度色散和自转速度的估计，并对样本中的运动学偏差进行了校正。有人认为，这些数据与一个模型不一致，在该模型中，晕是由消散的、塌陷的云中的恒星形成的；然而，它们与由众多独立演化的气体云形成的晕星是一致的。然后建立了372颗运动选择晕星样本的金属丰度分布，以期考虑数据中的选择效应。球状团簇的金属丰度分布与平均为10个元素/碎片的随机模型符合得很好。参考文献153。
Stars previously identified as having UV excesses are observed at 1-A resolution in the Ca II K-line region. Comparisons of these data with other samples and with Monte Carlo simulations involving a single component halo have yielded estimates of halo velocity dispersions and rotation velocity, corrected for the kinematic biases in the sample. It is suggested that the data are not consistent with a model in which the halo formed from star formation in a dissipating, collapsing cloud; they are, however, reconcilable with the formation of the halo stars by numerous, independently evolving gas clouds. The metallicity distribution of a sample of 372 kinematically selected halo stars is then constructed, with a view to selection effects in the data. Good agreement is noted between the globular cluster metallicity distribution and a stochastic model with a mean of 10 enrichments/fragment. 153 refs.