THE FORMATION OF GRAPHITE WHISKERS IN THE PRIMITIVE SOLAR NEBULA
THE FORMATION OF GRAPHITE WHISKERS IN THE PRIMITIVE SOLAR NEBULA
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DOI：
10.1088/2041-8205/710/1/l98
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发表时间：
2010-02
期刊：
影响因子：
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通讯作者：
J. Nuth;Y. Kimura;C. Lucas;F. Ferguson;N. Johnson
中科院分区：
文献类型：
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作者：
J. Nuth;Y. Kimura;C. Lucas;F. Ferguson;N. Johnson
有人认为，碳质晶粒在星际介质中被有效地破坏，必须在极低的压力和温度下原位重组，或者在更有利于晶粒生长的替代环境中重组。石墨晶须在钙铝包裹体和球粒等陨石中发现了与高温相相关的石墨晶须，这表明这种物质从原恒星星云中喷出可能会显著影响平均星际颗粒群的光学性质。我们通过实验研究了在原恒星系统中，由丰富的H2、CO和N2在可用的硅酸盐颗粒表面反应产生有机物质的费舍尔-托普施和哈伯-博世型反应的潜力。当石墨晶粒在875 K下反复暴露于H2、CO和N2中时，观察到石墨晶粒表面或表面形成了大量的石墨晶须。在致密的湍流星云中，这种延伸的晶须很可能被折断，碎片可能在极性喷流中被喷射出来，也可能在光子压力的作用下被输送到星云的外围。
It has been suggested that carbonaceous grains are efficiently destroyed in the interstellar medium and must either reform in situ at very low pressures and temperatures or in an alternative environment more conducive to grain growth. Graphite whiskers have been discovered associated with high-temperature phases in meteorites such as calcium aluminum inclusions and chondrules, and it has been suggested that the expulsion of such material from protostellar nebulae could significantly affect the optical properties of the average interstellar grain population. We have experimentally studied the potential for Fischer–Tropsch and Haber–Bosch type reactions to produce organic materials in protostellar systems from the abundant H2, CO, and N2 reacting on the surfaces of available silicate grains. When graphite grains are repeatedly exposed to H2, CO, and N2 at 875 K abundant graphite whiskers are observed to form on or from the surfaces of the graphite grains. In a dense, turbulent nebula, such extended whiskers are very likely to be broken off, and fragments could be ejected either in polar jets or by photon pressure after transport to the outer reaches of the nebula.