论文标题
关于IC 63的照明区域和阴影区域中灰尘晶粒的碰撞污染。
On the collisional disalignment of dust grains in illuminated and shaded regions of IC 63
论文作者
论文摘要
星际灰尘晶粒对齐会导致从紫外线到MM波长的极化，从而研究了磁场的几何形状和强度。在过去的几十年中，观察和理论导致建立了辐射比对扭矩（大鼠）机制，作为解释效果的主要候选人。通过定量良好的理论，极化不仅可以用于研究星际磁场，还可用于研究灰尘和其他环境参数。光线解离区（PDRS）及其强烈的各向异性辐射场，随之而来的快速$ \ rm h_ {2} $形成和高空间密度对比度为此类研究提供了丰富的环境。在这里，我们讨论了IC \ 63个星云的一项扩展的光学，NIR和MM波研究，显示出强大的$ \ rm h_ {2} $形式增强的对准，以及由于使用高分辨率$ \ rm hco^rm hco^{+rm hco^{+rm hco^{+} $（j = 1-1-1-1-1-1-0）而导致气体污垢碰撞引起的第一个直接经验证据。我们发现，相对量的极化量与$ \ rm hco^{+} $的色谱柱密度略有反对。但是，将光学仪表的视线分离到后面或前面的那些视线中，从$γ$ CAS可以看出，分布分为两个定义明确的集合，数据对应于\ shuquote {shaded}气体，具有较浅的斜坡。如果碰撞差异率与r $ _c \ propto n \ sqrt {t} $成正比，则预期的是，这是预期的。 \ enquote {Inlumined}和\ Esquote {shaded}视线样本的最佳拟合斜率在不确定性中同意，而两位温度h $ _2 $的正方形是Thi等人在Nebula中看到的。 （2009）。
Interstellar dust grain alignment causes polarization from UV to mm wavelengths, allowing the study of the geometry and strength of the magnetic field. Over last couple of decades observations and theory have led to the establishment of the Radiative Alignment Torque (RAT) mechanism as leading candidate to explain the effect. With a quantitatively well constrained theory, polarization can be used not only to study the interstellar magnetic field, but also the dust and other environmental parameters. Photo-dissociation Regions (PDRs), with their intense, anisotropic radiation fields, consequent rapid $\rm H_{2}$ formation, and high spatial density-contrast provide a rich environment for such studies. Here we discuss an expanded optical, NIR, and mm-wave study of the IC\,63 nebula, showing strong $\rm H_{2}$ formation-enhanced alignment and the first direct empirical evidence for disalignment due to gas-grain collisions using high-resolution $\rm HCO^{+}$(J=1-0) observations. We find that relative amount of polarization is marginally anti-correlated with column density of $\rm HCO^{+}$. However, separating the lines of sight of optical polarimetry into those behind, or in front of, a dense clump as seen from $γ$ Cas, the distribution separates into two well defined sets, with data corresponding to \enquote{shaded} gas having a shallower slope. This is expected if the decrease in polarization is caused by collisions since collisional disalignment rate is proportional to R$_C\propto n\sqrt{T}$. Ratios of the best-fit slopes for the \enquote{illuminated} and \enquote{shaded} samples of lines of sight agrees, within the uncertainties, with the square-root of the two-temperature H$_2$ excitation in the nebula seen by Thi et al. (2009).
