The 11B/10B Ratio of Local Interstellar Diffuse Clouds
The 11B/10B Ratio of Local Interstellar Diffuse Clouds
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本地星际弥漫云的 11B/10B 比率
DOI：
10.1086/305235
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
D. Knauth
中科院分区：
文献类型：
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作者：
D. Lambert;Y. Sheffer;S. Federman;J. Cardelli;U. Sofia;D. Knauth
利用B II 1362 Å线的HST/Goddard高分辨率谱仪，测量了向ζ Oph、κ Ori和δ Sco方向扩散星际云中气体的同位素比值11B/10B。在测量误差范围内，三条视线的平均值为11B/10B = 3.4±0.7，与太阳系的比值4.05相当。这些结果表明，后者的值并不是高度反常的，而对于由高能宇宙射线控制的散裂反应产生的硼，其比值高于2.5，很可能需要一个一般的解释。观测到的比率与低能量（“猎户座”）宇宙射线的散裂或II型超新星中中微子引起的碳散裂产生的额外硼相一致。弥散云中B的总丰度比陨石值少5倍。B的耗尽与Cu和Ga的发现一致，这两种元素的冷凝温度与B相似。
The isotopic ratio 11B/10B of gas in diffuse interstellar clouds toward ζ Oph, κ Ori, and δ Sco is measured using HST/Goddard High Resolution Spectrograph echelle spectra of the B II 1362 Å line. To within the errors of measurement, the three lines of sight give identical results for a mean value of 11B/10B = 3.4 ± 0.7, a value quite similar to the solar system ratio of 4.05. These results show that the latter value is not highly anomalous and that a ratio higher than 2.5, as predicted for boron produced from spallation reactions controlled by high-energy cosmic rays, most probably requires a general explanation. The observed ratio is consistent with additional boron production either by spallation by low-energy ("Orion") cosmic rays or by neutrino-induced spallation of carbon in Type II supernovae. The total abundance of B in the diffuse clouds is a factor of 5 less than the meteoritic value. This depletion of B is consistent with that found for Cu and Ga, two elements with a condensation temperature similar to B.