标题： 蓝发光与星际介质中小型PAH的存在 显示英文标题

标题： Blue Luminescence and the Presence of Small PAHs in the ISM

摘要： 蓝发光（BL）最初是在一颗原行星状星云——围绕后渐近巨星分支（post-AGB）恒星HD 44179的红矩形（RR）区域中被发现。 BL 被归因于由小的、含3到4个环的中性多环芳烃（PAH）分子的荧光现象，并被认为仅限于红矩形环境，在这种环境中，这些小分子正在被积极地产生并受到稠密的恒星盘的屏蔽，从而免受恶劣的星际辐射的影响。 本文介绍了在几个由温度介于10,000至23,000开尔文之间的恒星照亮的普通反射星云中检测到的BL光谱。所有这些星云都被知悉还表现出被称为芳香发射特征（AEFs）的红外发射特征，这些特征与大PAH分子有关。 我们展示了这些星云中BL的空间分布情况。对于Ced 112来说，BL的空间分布与归因于AEFs的中红外发射结构相关联。 这些观测结果提供了颗粒物加工以及可能的小颗粒和大分子从较大团块中原位形成的证据。 最重要的是，在这些普通的反射星云中检测到BL表明BL载体是星际介质（ISM）中的普遍成分，并且并不局限于红矩形的独特环境。 显示英文摘要

摘要： Blue Luminescence (BL) was first discovered in a proto-planetary nebula, the Red Rectangle (RR) surrounding the post-AGB star HD 44179. BL has been attributed to fluorescence by small, 3-4 ringed neutral polycyclic aromatic hydrocarbon (PAH) molecules, and was thought to be unique to the RR environment where such small molecules are actively being produced and shielded from the harsh interstellar radiation by a dense circumstellar disk. In this paper we present the BL spectrum detected in several ordinary reflection nebulae illuminated by stars having temperatures between 10,000 -- 23,000 K. All these nebulae are known to also exhibit the infrared emission features called aromatic emission features (AEFs) attributed to large PAHs. We present the spatial distribution of the BL in these nebulae. In the case of Ced~112, the BL is spatially correlated with mid-IR emission structures attributed to AEFs. These observations provide evidence for grain processing and possibly for in-situ formation of small grains and large molecules from larger aggregates. Most importantly, the detection of BL in these ordinary reflection nebulae suggests that the BL carrier is an ubiquitous component of the ISM and is not restricted to the particular environment of the RR.