论文标题
星际介质中HNC的第一个中红外检测:向猎户座热芯探测极端环境
The First Mid-Infrared Detection of HNC in the Interstellar Medium: Probing the Extreme Environment Towards the Orion Hot Core
论文作者
论文摘要
我们介绍了星际培养基中HNC和H13CN的第一个中型(miR)检测,以及许多已解决的HCN Rovbritation Transitions。我们的观测值跨越12.8至22.9微米,朝着热核Orion IRC2占用,该热核Orion IRC2在红外线天文学(Sofia)的平流层观测值(Sofia)上获得了梯形 - 交叉 - echelle光谱仪。异常,〜5 km/s,分辨率区分了HNC和HCN P,Q和R分支的单个Rovbibrational Transition;和H13CN R分支。这允许直接测量物种的激发温度,色谱柱密度和相对丰度。 HNC和H13CN表现出-7 km/s的局部标准休息速度,可能与附近无线电源I的流出相关,激发温度约为100 k。我们解决了HCN的两个速度组件,主要成分在-7 km/s的温度下也不是165K。迄今为止测量的热核心中心的组件。对于猎户座的半乳酸距离而言,派生的12c/13c = 13低于预期,但是对于这种极端环境,预期派生的HCN/HNC = 72。与以前的亚MM和MM观测值相比,我们对该区域的索非亚线调查表明,已解决的miR分子跃迁正在探测一个独特的物理成分,并隔离了最接近热核的化学性质。
We present the first mid-infrared (MIR) detections of HNC and H13CN in the interstellar medium, and numerous, resolved HCN rovibrational transitions. Our observations span 12.8 to 22.9 micron towards the hot core Orion IRc2, obtained with the Echelon-Cross-Echelle Spectrograph aboard the Stratospheric Observatory for Infrared Astronomy (SOFIA). Exceptional, ~5 km/s, resolution distinguishes individual rovibrational transitions of the HNC and HCN P, Q, and R branches; and the H13CN R branch. This allows direct measurement of the species' excitation temperatures, column densities, and relative abundances. HNC and H13CN exhibit a local standard rest velocity of -7 km/s that may be associated with an outflow from nearby radio source I and an excitation temperature of about 100 K. We resolve two velocity components for HCN, the primary component also being at -7 km/s with temperature 165 K. The hottest component, which had never before been observed, is at 1 km/s with temperature 309 K. This is the closest component to the hot core's centre measured to date. The derived 12C/13C=13 is below expectation for Orion's Galactocentric distance, but the derived HCN/HNC=72 is expected for this extreme environment. Compared to previous sub-mm and mm observations, our SOFIA line survey of this region shows that the resolved MIR molecular transitions are probing a distinct physical component and isolating the chemistry closest to the hot core.