Origin of olivine particles in comets

（1）在7 μ m至200 μ m的波长范围内测量橄榄石颗粒的光学常数（Mukai和Koike 1990，Icarus 87，180）。这些结果证实了假设，橄榄石是一个载体的双峰结构中观察到的几个彗星在10妈妈区域。（2）橄榄石颗粒一般在高温（>1500 K）下凝结。解释橄榄石与彗星核内的冰粒子共存的一种可能性是，太阳附近的粒子向彗星形成的区域进行径向运输。我们已经检查了多孔聚集体上的辐射压力，以研究橄榄石蓬松颗粒的运动（Mukai等人，1992年，宇航员Astrophys。出版中）。结果表明，蓬松粒子与致密球体上的辐射力存在显著差异。(3)We已经表明（Mukai 1991，IAU Col. 126，Kluwer，第371页），由于不规则形状颗粒上的电荷引起的静电力，蓬松尘埃颗粒的碎裂在P/Halley彗星彗发中检测到的非常小的颗粒的产生中起着重要的作用。(4)It Mukai and Mukai 1990，Icarus 86，257，Mukai et al.1991，IAU Col.126，Kluwer，p.249）发现，这些蓬松聚集体的尘埃模型可以解释彗星中观测到的日冕测量数据。

(1)The optical constants of olivine particles were measure in the wavelengths from 7 mum to 200 mum(Mukai and Koike 1990, Icarus 87, 180). These results have confirmed the hypothesis that olivine is a carrier of a twin-peaked structure in the 10 mum region observed in several-comets.(2)Olivine particles, in general, are condenced at high temperatures(>1500 K). One possibility to explain the coexistence of olivine with icy particles inside the cometary nucleus is a radial transportation of particles near the sun to the region where the comet will be formed. We have examined the radiation pressure forces on porous aggragates to study a motion of olivine fluffy particles(Mukai et al. 1992, Astron. Astrophys. in press). It is found a significant difference of radiation forces on fluffy particles compared with those on compact spheres.(3)We have shown(Mukai 1991, IAU Col. 126, Kluwer, p. 371)that a fragmentation of fluffy dust particles due to electrostatic forces caused by electric charges on irregularly shaped particle plays an important role in the production of very small particles detected in the cometary coma of Comet P/Halley.(4)It is found(Mukai and Mukai 1990, Icarus 86, 257, Mukai et al. 1991, IAU Col. 126, Kluwer, p. 249)that these dust modelsfor fluffy aggregates can explain the photopolarimetric data observed in comets.