论文标题
在毫米波长下，与频谱指数相关的晶粒尺寸分布与光谱指数
Relating grain size distributions in circumstellar discs to the spectral index at millimetre wavelengths
论文作者
论文摘要
在光谱能量分布（SED）中看到的过量发射通常用于推断原星盘和碎屑盘中发射偶尔灰尘的特性。最值得注意的是，灰尘尺寸的分布和碰撞物理的细节来自长波长的SED斜率。本文回顾了通常使用的近似值，并将它们与热发射的数值结果进行了对比。被推断的尺寸分布指数显示，对观察到的子（mm）光谱指数比以前考虑的更大，更敏感。这种作用是由于从具有体积吸收的小晶粒到较大的谷物的过渡而产生的，这些谷物被折射率的真实和想象中的部分所控制，这些谷物吸收并发出靠近其表面。较陡的尺寸分布表明材料强度或冲击速度的尺寸依赖性更强，或者是效率较低的运输或侵蚀过程。由于对长波长的材料组成，孔隙率和光学特性的了解不足，因此仍然存在强烈的不确定性。
The excess emission seen in spectral energy distributions (SEDs) is commonly used to infer the properties of the emitting circumstellar dust in protoplanetary and debris discs. Most notably, dust size distributions and details of the collision physics are derived from SED slopes at long wavelengths. This paper reviews the approximations that are commonly used and contrasts them with numerical results for the thermal emission. The inferred size distribution indexes are shown to be greater and more sensitive to the observed sub(mm) spectral indexes than previously considered. This effect results from aspects of the transition from small grains with volumetric absorption to bigger grains that absorb and emit near to their surface, controlled by both the real and the imaginary part of the refractive index. The steeper size distributions indicate stronger size-dependence of material strengths or impact velocities or, otherwise, less efficient transport or erosion processes. Strong uncertainties remain because of insufficient knowledge of the material composition, porosity, and optical properties at long wavelengths.
