Interstellar dust in the Local Cloud surrounding the Sun
Interstellar dust in the Local Cloud surrounding the Sun
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太阳周围本地云中的星际尘埃
DOI：
10.1093/mnras/stv427
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发表时间：
2015
影响因子：
4.8
通讯作者：
Hiroshi Kimura
中科院分区：
文献类型：
--
作者：
Ricci;C.;Ueda;Y. et al.;Hiroshi Kimura
基于最近关于由单个连续云（称为本地云）组成的本地星际介质的观点，我们研究了本地云中冲击波传播对星际尘埃的破坏。我们调查气相柱密度的尘埃形成的元素在文献中，以确定如何尘埃破坏分数随角度从云的短轴。我们的研究结果表明，激波的传播摧毁了大约20%的星际尘埃，这些尘埃指向云的短轴，指向运动的反顶点附近，激波小于100 km s−1，比以前预期的要弱。在云运动的顶点，当地云的气尘比约为120，有机形成元素占尘埃阶段质量的40%。我们发现，硅和镁之间的气相丰度的相关性是一致的硅酸盐颗粒的破坏顽火辉石化学计量。我们还从尘埃相元素丰度和尘埃形成元素之间的相关性得出了星际尘埃最合理的组成。我们认为，星际尘埃的主要成分是有机物质，镁硅酸盐和铁合金，而次要的尖晶石和硫化铁。由于在进入太阳系的颗粒中没有检测到有机物质，我们认为星际尘埃的成分在进入内太阳系的途中可能不会保持完整。
On the basis of the most recent view on the local interstellar medium consisting of a single continuous cloud, termed the Local Cloud, we study the destruction of interstellar dust by the propagation of a shock wave in the Local Cloud. We survey gas-phase column densities of dust-forming elements in the literature to determine how the dust destruction fraction varies with the angle from the minor axis of the cloud. Our results indicate that the propagation of a shock wave destroyed approximately 20 per cent of interstellar dust towards the minor axis of the cloud pointing near the anti-apex of motion with a shock of <100 km s−1, weaker than previously expected. The gas-to-dust ratio of the Local Cloud is approximately 120 towards the apex of cloud motion and organic-forming elements occupy 40 per cent of the mass in the dust phase. We find that a correlation in the gas-phase abundances between silicon and magnesium is consistent with the destruction of silicate grains with enstatite stoichiometry. We also derive the most plausible composition of interstellar dust from the dust-phase elemental abundances and the correlations between the dust-forming elements. We suggest that the major constituents of interstellar dust are organic materials, magnesium silicates and iron alloys, while the minor ones are spinels and iron sulphides. Since no organic materials have been detected in the grains that penetrate into the Solar system, we claim that the composition of interstellar dust may not remain intact en route to the inner Solar system.