Photophoretic transport of hot minerals in the solar nebula
Photophoretic transport of hot minerals in the solar nebula
复制标题
太阳星云中热矿物的光泳传输
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
S. Charnoz
中科院分区：
文献类型：
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作者：
A. Moudens;O. Mousis;J. Petit;G. Wurm;D. Cordier;S. Charnoz
上下文在大量彗星中发现了高温矿物，在星尘使命任务返回的怀尔德2号彗星的样本中也发现了高温矿物。与此同时，对年轻恒星系统中热矿物质分布的观测表明，这些物质产生于原始星云的内部，并在彗星形成区向外输送。目标。我们调查的可能性，电泳提供了一个可行的机制，从太阳系内部的彗星形成的地区的高温材料。方法.我们使用太阳星云的时间依赖盘模型的网格来量化热矿物可以从盘的内部向其外部区域传输的距离范围，作为它们的大小（10 - 5到10 - 1 m）和密度（500和1000 kg m-3）的函数。这些模型还将产生关于盘属性的信息（内部间隙的半径、初始质量和盘的寿命）。这里考虑的粒子是以聚集体的形式存在的，它们可能是由热矿物单个颗粒组装而成的，这些颗粒的尺寸可以小到亚微米级，并在太阳星云最热的部分凝结形成。我们的粒子传输模型包括光泳、辐射压力和气体阻力。结果根据假设的盘参数和粒子密度，10 −2到10 −1 m的聚集体可以在很短的时间尺度（不超过几十万年）内到达原始星云中的日心距离高达135 Au。10 −3 m的粒子与较大的粒子遵循相同的轨迹，但它们的最大迁移距离不超过10 26 Au，并且在盘中的较晚时期达到。另一方面，10 −5到10 −4 m的聚集体在太阳星云的演化过程中不断向外推。根据所采用的盘参数，这些粒子可以在星云消散之前很好地到达星云的外缘。结论.我们的模拟表明，无论采用太阳星云模型，电泳是一种机制，可以解释热温度矿物在彗星的形成区域的存在。彗星可能有时间捕获从太阳系内部输送来的尘埃，无论是在吸积过程中，还是在粒子到达形成位置之前结束生长的情况下，彗星都有时间将这些尘埃捕获在其内部，或者以壳的形式围绕其表面。
Context. Hot temperature minerals have been detected in a large number of comets and were also identified in the samples of Comet Wild 2 that were returned by the Stardust mission. Meanwhile, observations of the distribution of hot minerals in young stellar systems suggest that these materials were produced in the inner part of the primordial nebula and have been transported outward in the formation zone of comets. Aims. We investigate the possibility that photophoresis provides a viable mechanism to transport high-temperature materials from the inner solar system to the regions in which the comets were forming. Methods. We use a grid of time-dependent disk models of the solar nebula to quantify the distance range at which hot minerals can be transported from the inner part of the disk toward its outer regions as a function of their size (10 −5 to 10 −1 m) and density (500 and 1000 kg m −3 ). These models will also yield information on the disk properties (radius of the inner gap, initial mass, and lifetime of the disk). The particles considered here are in the form of aggregates that presumably were assembled from hot mineral individual grains ranging down to submicron sizes and formed by condensation within the hottest portion of the solar nebula. Our particle-transport model includes the photophoresis, radiation pressure, and gas drag. Results. Depending on the postulated disk parameters and the density of particles, 10 −2 to 10 −1 m aggregates can reach heliocentric distances up to ∼35 AU in the primordial nebula over very short timescales (no more than a few hundred thousand years). 10 −3 m particles follow the same trajectory as the larger ones but their maximum migration distance does not exceed ∼26 AU and is reached at later epochs in the disks. On the other hand, 10 −5 to 10 −4 m aggregates are continuously pushed outward during the evolution of the solar nebula. Depending on the adopted disk parameters, these particles can reach the outer edge of the nebula well before its dissipation. Conclusions. Our simulations suggest that irrespective of the employed solar nebula model, photophoresis is a mechanism that can explain the presence of hot temperature minerals in the formation region of comets. Comets probably had the time to trap the dust transported from the inner solar system either in their interior during accretion or in the form of shells surrounding their surface if they ended their growth before the particles reached their formation location.