标题： NGC 7023星际发射特征的斯皮策15-20微米光谱 显示英文标题

标题： The 15 - 20 Micron Spitzer Spectra of Interstellar Emission Features in NGC 7023

摘要： 我们展示了来自斯皮策望远镜红外光谱仪（IRS）的15至20微米长缝光谱，对象是NGC 7023。 我们在反射星云中观测到最近发现的星际发射特征，波长分别为15.9、16.4、17.0、17.4、17.8和18.9微米。 16.4微米发射特征在恒星西北部的光解前沿附近达到峰值，芳香族发射特征（AEFs）在3.3、6.2和11.3微米处也是如此。 因此，16.4微米发射特征很可能与AEFs有关，并通过非平衡发射辐射。 相比之下，新的18.9微米发射特征随着恒星距离单调减小。 我们考虑了18.9微米特征的候选物种，包括多环芳烃、富勒烯和金刚石。 我们描述了识别18.9微米特征载体所需的未来实验室和观测研究。 显示英文摘要

摘要： We present 15 - 20 micron long-slit spectra, from the Infrared Spectrograph (IRS) on Spitzer, of NGC 7023. We observe recently-discovered interstellar emission features, at 15.9, 16.4, 17.0, 17.4, 17.8, and 18.9 microns, throughout the reflection nebula. The 16.4 micron emission feature peaks near the photodissociation front northwest of the star, as do the aromatic emission features (AEFs) at 3.3, 6.2 and 11.3 microns. The 16.4 micron emission feature is thus likely related to the AEFs and radiates by non-equilibrium emission. The new 18.9 micron emission feature, by contrast, decreases monotonically with stellar distance. We consider candidate species for the 18.9 micron feature, including polycyclic aromatic hydrocarbons, fullerenes, and diamonds. We describe future laboratory and observational research needed to identify the 18.9 micron feature carrier.