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Heating of Dust Particles and Chondrule Formation Induced by Shock-Waves in Upper Layer of Protoplanetary Disks Generated by X-Ray Flares

X射线耀斑产生的原行星盘上层冲击波引起的尘埃颗粒加热和球粒形成

基本信息

批准号：
17540211
负责人：
NAKAMOTO Taishi
金额：
$ 1.95万
依托单位：
Tokyo Institute of Technology (2006-2007)University of Tsukuba (2005)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

项目摘要

We studied the phenomen that a magnetic bubble caused by X-Ray flare of the central star generates the shock waves at the surface of protoplanetary disks around the central star. And we looked at the characteristics of shock waves to examine if they can heat dust particles in the disk enough to melt them and form chondrules based on the shock-wave heating model for chondrule formation. Especially, we focused on following three points : (1) if such an phenomen may take place, (2) if it occurs what kind of effects they may bring to materials in the disk, and (3) if we can know the presence of the phenomen by making observation astronomically and meteoritically. To approach these problems, we have conducted Magneto-Hydrodynamics (MHD) numerical simulations, radiative transfer numerical simulations, analytic investigations, and so forth.Our MHD simulations have revealed that shock waves can be formed by the magnetic bubbles associated with X-Ray flares. And some of those shock waves turned … More out to be appropriate for chondrule formation and crystallization of dust particles. Namely, (a) dust particles in the disk region closer than 3 AU from the central star can be heated enough, and (b) it is unlikely that dust particle in a region further than about 5 AU are heated by the shock waves because the bubble would not reach that region due to the collimation.On the other hand, thanks to the detailed simulations, we can now discuss places where dust particles are heated to form chondrules and/or crystallize precisely. And we can discuss the possibility that heated and crystallized dust particles may be incorporated in comets. This discussion implies that crystallized dust particles in observed comets should be transferred from the inner region of the solar system, because the shock wave heating can only take place in a region closer than 5 AU.Some possible transfer mechanisms of dust particles have been proposed so far, but we need to investigate those mechanisms in detail in the future. Less

我们研究了中心恒星X射线耀斑产生的磁泡在中心恒星周围原行星盘表面产生激波的现象。我们观察了冲击波的特征，以检验它们是否能加热圆盘中的尘埃颗粒，使其融化，并基于冲击波加热模型形成球粒。我们着重研究了以下三点：(1)如果可能发生这种现象，(2)如果发生这种现象，会给盘中的物质带来什么样的影响，以及(3)是否可以通过天文和流星观测来知道这种现象的存在。为了解决这些问题，我们进行了磁流体力学(MHD)数值模拟、辐射传输数值模拟、解析研究等。我们的MHD模拟表明，激波可以由与X射线耀斑相关的磁泡形成。其中一些冲击波变成了…更适合球粒的形成和尘埃颗粒的结晶。也就是说，(A)距离中心恒星更近3AU的盘状区域中的尘埃粒子可以被足够的加热，以及(B)比约5AU更远的区域中的尘埃粒子不太可能被激波加热，因为由于准直，气泡不会到达该区域。另一方面，由于详细的模拟，我们现在可以讨论尘埃粒子被加热以形成球粒和/或精确结晶的地方。我们还可以讨论被加热和结晶的尘埃颗粒可能合并到彗星中的可能性。这一讨论表明，观测到的彗星中的结晶尘埃粒子应该从太阳系的内部区域转移，因为激波加热只能发生在接近5AU的区域。到目前为止，已经提出了一些可能的尘埃粒子转移机制，但我们需要在未来详细地研究这些机制。较少