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首页> 外文期刊>The Astrophysical journal >DIRECT MEASUREMENT OF THE INNER RADIUS OF THE DUST SHELL AROUND THE COOL SUPERGIANT STAR α SCORPII
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DIRECT MEASUREMENT OF THE INNER RADIUS OF THE DUST SHELL AROUND THE COOL SUPERGIANT STAR α SCORPII

机译：直接测量酷星αSCORPII周围粉尘内部半径的直接测量

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摘要

We have measured high-precision 10 μm image profiles of the supergiant star a Scorpii using a scanned linear array on a 3 m telescope. These image profiles have high signal-to-noise ratio and so can be used to study circumstellar structure with spatial resolution at and slightly finer than the diffraction limit of the telescope, FWHM ～0.7″. We find the inner radius of the dust shell to be about 0.6″, or 110 AU. At this circumstellar radius, the temperature of the dust is very low compared to the temperature at which silicate grains evaporate, indicating that grain condensation is impeded compared to equilibrium conditions if the dust shell morphology is constant in time. In this picture, grains may grow to a relatively large size soon after condensation. Alternatively, this large temperature discrepancy may suggest that dust formation is episodic, and the shell that we observed was originally formed closer to the star but has moved outward with the general circumstellar outflow of gas. In either case, for most published values of the mass-loss rate, our data can be used to argue that circumstellar dust grains around α Sco are predominantly large in size, so the size distribution seen in the general interstellar medium is not present at the time of grain formation.
机译：我们已经使用3 m望远镜上的扫描线性阵列测量了超大恒星Scorpii的高精度10μm图像轮廓。这些图像轮廓具有很高的信噪比，因此可用于研究空间分辨率为或略小于望远镜的衍射极限FWHM〜0.7“的星际结构。我们发现防尘壳的内半径约为0.6英寸，即110 AU。在此星际半径处，粉尘的温度与硅酸盐颗粒蒸发的温度相比非常低，这表明如果尘埃壳形态在时间上恒定，则与平衡条件相比，粉尘凝结会受到阻碍。在这张照片中，凝结后不久晶粒可能会长大。或者，这种较大的温度差异可能表明尘埃形成是偶发的，而我们观察到的壳最初形成时更靠近恒星，但随着气体的整体绕星外流而向外移动。无论哪种情况，对于大多数公布的质量损失率值，我们的数据都可以用来论证αSco周围的星际尘埃颗粒尺寸很大，因此在普通星际介质中看不到尺寸分布晶粒形成的时间。

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