转捩盘的毫米光谱指数及其与腔半径的关系
Millimetre spectral indices of transition disks and their relation to the cavity radius
摘要：
过渡盘是内部尘埃空腔耗尽的原行星盘，是研究压力冲击存在下尘埃演化的绝佳候选者。空腔外边缘的一个压力隆起使来自外部区域的尘埃颗粒停止向恒星的快速向内迁移，并有效地增长到毫米大小。与行星的动力学相互作用一直是解释内盘清理的最令人兴奋的理论之一。我们寻找证据的毫米尘埃粒子在过渡盘的存在，通过测量他们的光谱指数与新的和可用的光度数据。本文研究了尘埃耗尽腔的大小对圆盘积分毫米光谱指数的影响。本文介绍了用PdBI对LkHa 330、UXTauA、LRLL 31和LRLL 67四个过渡盘进行的3mm测光观测。我们使用它们在345GHz的通量的可用值来计算它们的光谱指数，以及20个过渡盘的样本的光谱指数。我们比较了两种模型的观测结果。在第一组模型中，我们考虑凝聚和破碎的尘埃盘中的空腔是由一个大质量的行星位于不同的位置。第二组模型假设磁盘截断内部在不同的半径和幂律粉尘粒度分布，其中颗粒的最大尺寸的计算考虑湍流的破坏性碰撞的来源。我们表明，过渡盘的综合光谱指数高于常规的原行星盘。对于转捩盘，测得的光谱指数与腔半径正相关的概率为95%。需要过渡盘的高角分辨率成像来区分尘埃捕获情况和截断盘情况。
英文摘要：
Transition disks are protoplanetary disks with inner depleted dust cavities and excellent candidates to investigate the dust evolution under the existence of a pressure bump. A pressure bump at the outer edge of the cavity allows dust grains from the outer regions to stop their rapid inward migration towards the star and efficiently grow to millimetre sizes. Dynamical interactions with planet(s) have been one of the most exciting theories to explain the clearing of the inner disk. We look for evidence of the presence of millimetre dust particles in transition disks by measuring their spectral index with new and available photometric data. We investigate the influence of the size of the dust depleted cavity on the disk integrated millimetre spectral index. We present the 3mm photometric observations carried out with PdBI of four transition disks: LkHa330, UXTauA, LRLL31, and LRLL67. We use available values of their fluxes at 345GHz to calculate their spectral index, as well as the spectral index for a sample of twenty transition disks. We compare the observations with two kind of models. In the first set of models, we consider coagulation and fragmentation of dust in a disk in which a cavity is formed by a massive planet located at different positions. The second set of models assumes disks with truncated inner parts at different radius and with power-law dust size distributions, where the maximum size of grains is calculated considering turbulence as the source of destructive collisions. We show that the integrated spectral index is higher for transition disks than for regular protoplanetary disks. For transition disks, the probability that the measured spectral index is positively correlated with the cavity radius is 95%. High angular resolution imaging of transition disks is needed to distinguish between the dust trapping scenario and the truncated disk case.
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