A New Model for the Evolution of Light Elements in an Inhomogeneous Galactic Halo
A New Model for the Evolution of Light Elements in an Inhomogeneous Galactic Halo
复制标题
非均匀银河晕中轻元素演化的新模型
DOI：
10.1086/319049
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
Y. Yoshii
中科院分区：
文献类型：
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作者：
T. Suzuki;Y. Yoshii
我们利用最近由Tsujimoto等人提出的基于超新星(SNE)和宇宙射线(CRS)贡献的超新星诱导的化学演化模型，对银晕早期轻元素Li、Be和B的演化进行了预测。和铃木等人。这个模型有很大的优势，可以自洽地处理各种元素，即使在不均匀的条件下也是如此，因为它可能是由SN爆炸引发的随机恒星形成过程引起的。从我们的模型中最重要的预测是，在晕群演化的非常早期阶段，极贫金属星中的轻元素丰度可能被用作年龄指标，此时大多数恒星中的重元素丰度(“金属度”)主要是由于附近SN事件而导致的局部金属丰度，并且与年龄的相关性很差。年龄-元素丰度图中恒星的预期频率分布曲线图表明，最好的“宇宙钟”是~6Li丰度。我们导出了各种宇宙线参数之间的关系，如SNE输入CRS的能量、CRS的光谱形状和CRS的化学成分，并发现我们可以很好地再现最近在贫金属星上对6Li、Be和B的观测。虽然我们的模型对某些宇宙线参数是成功的，但每个SN的高能粒子应该会吸收比目前银盘所需的更大的能量。我们讨论了早期星系活动星系核活动的另一种假说，作为CRS的另一种可能的加速器。
We present predictions of the evolution of the light elements, Li, Be, and B, in the early epochs of the Galactic halo, using a model of supernova-induced chemical evolution based on contributions from supernovae (SNe) and cosmic rays (CRs), as recently proposed by Tsujimoto et al. and Suzuki et al. This model has the great advantage of treating various elements self-consistently, even under inhomogeneous conditions, as might arise from stochastic star formation processes triggered by SN explosions. The most important prediction from our model is that the abundances of light elements in extremely metal-poor stars might be used as age indicators in the very early stages of an evolving halo population, at times when the abundances of heavy elements ("metallicity") in most stars are dominated by local metal enrichment due to nearby SN events, and is poorly correlated with age. Plots of the expected frequency distribution of stars in the age versus elemental abundance diagram show that the best "cosmic clock" is the 6Li abundance. We have derived relationships among various cosmic-ray parameters such as energy input to CRs by SNe, the spectral shape of the CRs, and the chemical composition in CRs, and find that we can reproduce very well recent observations of 6Li, Be, and B in metal-poor stars. Although our model is successful for certain sets of cosmic-ray parameters, larger energy should be absorbed by energetic particles from each SN than required to the current situation of Galactic disk. We discuss an alternative hypothesis of active galactic nuclei activity in the early Galaxy as another possible accelerator of CRs.
DOI：
10.1086/301409
发表时间：
2000-03
期刊：
The Astronomical Journal
影响因子：
--
作者：
M. Chiba;T. Beers
通讯作者：
M. Chiba;T. Beers