论文标题
OMC-1对OMC-3的成像线调查
An imaging line survey of OMC-1 to OMC-3
论文作者
论文摘要
目的：我们的目的是在猎户座北部的分子云的北部不同区域的1.3 mm窗口中确定主要的分子冷却线和特征发射特征。通过定义和分析模板区域，我们还打算帮助解释来自更遥远的来源的观测值，而这些观察结果无法轻易地在空间上解决。 方法：我们分析了一项成像线调查，该调查涵盖了OMC-1至OMC-3的面积，从200.2到281.8 GHz在Apex望远镜上使用PI230接收器获得。蒙版用于定义具有不同特性（例如柱密度或温度范围）的区域，从中获得平均光谱。为每个区域拟合29种分子种（55个同位素）的线，以获得相应的总强度。 结果：我们发现诸如Orion KL之类的强大来源对较大尺度上的发射有明显的影响。尽管没有在空间上扩展，但它们的线排放量对大型区域的平均光谱产生了显着贡献。相反，密集的，像OMC-2和OMC-3（例如增强的n $ _ {2} $ h $^{+} $发射和低HCN/HNC比率）的发射签名似乎很难在较大的尺度上被较大的尺度上拾取，在较大的尺度上，它们被强源的签名而被赋予。在所有地区，HCO $^{+} $似乎对总强度贡献了3％至6％，这是所有明亮物种的最稳定值。 n $ _ {2} $ h $^{+} $显示与列密度最强的相关性，但与典型的高密度示踪剂（如HCN，HCO $^{+} $，h $ _ {2} $ co或HNC）没有典型的高密度示踪剂。与紫外线照明，CN/HNC和CN/HCO $^{+} $相关的常见线比在较大尺度上显示模棱两可的结果，这表明识别紫外线照明材料可能更具挑战性。 HCN/HNC比可能与不同尺度上的温度有关。
Aims: Our aim is to identify the dominant molecular cooling lines and characteristic emission features in the 1.3 mm window of distinct regions in the northern part of the Orion A molecular cloud. By defining and analysing template regions, we also intend to help with the interpretation of observations from more distant sources which cannot be easily spatially resolved. Methods: We analyse an imaging line survey covering the area of OMC-1 to OMC-3 from 200.2 to 281.8 GHz obtained with the PI230 receiver at the APEX telescope. Masks are used to define regions with distinct properties (e.g. column density or temperature ranges) from which we obtain averaged spectra. Lines of 29 molecular species (55 isotopologues) are fitted for each region to obtain the respective total intensity. Results: We find that strong sources like Orion KL have a clear impact on the emission on larger scales. Although not spatially extended, their line emission contributes substantially to spectra averaged over large regions. Conversely, the emission signatures of dense, cold regions like OMC-2 and OMC-3 (e.g. enhanced N$_{2}$H$^{+}$ emission and low HCN/HNC ratio) seem to be difficult to pick up on larger scales, where they are eclipsed by signatures of stronger sources. In all regions, HCO$^{+}$ appears to contribute between 3% and 6% to the total intensity, the most stable value for all bright species. N$_{2}$H$^{+}$ shows the strongest correlation with column density, but not with typical high-density tracers like HCN, HCO$^{+}$, H$_{2}$CO, or HNC. Common line ratios associated with UV illumination, CN/HNC and CN/HCO$^{+}$, show ambiguous results on larger scales, suggesting that the identification of UV illuminated material may be more challenging. The HCN/HNC ratio may be related to temperature over varying scales.
