We present a high-sensitivity spectral line survey of the high-mass star-forming region Orion KL in the 325-360 GHz frequency band. The survey was conducted at the Caltech Submillimeter Observatory on Mauna Kea, Hawaii. The sensitivity achieved is typically 0.1-0.5 K and is limited mostly by the sideband separation method utilized. We find 717 resolvable features consisting of 1004 lines, among which 60 are unidentified. The identified lines are due to 34 species and various isotopomers. Most of the unidentified lines are weak, and many of them most likely due to isotopomers or vibrationally or torsionally excited states of known species with unknown line frequencies, but a few reach the 2-5 K level. No new species have been identified, but we were able to strengthen evidence for the identification of ethanol in Orion and found the first nitrogen sulfide line in this source. The molecule dominating the integrated line emission is S02, which emits twice the intensity of CO, followed by SO, which is only slightly stronger than CO. In contrast, the largest number of lines is emitted from heavy organic rotors like HCOOCH3, CH3CH2CN, and CH3OCH3, but their contribution to the total flux is unimportant. CH3OH is also very prominent, both in the number of lines and in integrated flux. An interesting detail of this survey is the first detection of vibrationally excited HCN in the v2 = 2 state, 2000 K above ground. Clearly this is a glimpse into the very inner part of the Orion hot core.

中文翻译：

---

Orion KL在325至360 GHz范围内的线路测量。

我们提出了在325-360 GHz频带内高质量恒星形成区Orion KL的高灵敏度谱线调查。这项调查是在夏威夷茂纳基亚的Caltech亚毫米观测站进行的。达到的灵敏度通常为0.1-0.5 K，并且主要受所用边带分离方法的限制。我们发现717个可分辨特征由1004条线组成，其中60条未被识别。所确定的品系归因于34种和各种同功异构体。大多数无法识别的谱系都很弱，其中许多很可能是由于已知物种的同位素异构体或振动或扭转激发态，而谱系频率未知，但有一些达到2-5 K的水平。没有发现新物种，但是我们能够加强在Orion中鉴定乙醇的证据，并在该来源中找到了第一条硫化氮系。占主导地位的整体分子是S02，其发射强度是CO的两倍，其次是SO，其强度仅比CO稍强。相反，最大数量的线是从重型有机转子（如HCOOCH3，CH3CH2CN和CH3OCH3，但它们对总通量的贡献并不重要。CH3OH在生产线数和总通量方面也非常突出。这项调查的一个有趣的细节是首次检测到在高于地面2000 K的v2 = 2状态下的振动激发的HCN。显然，这是Orion热核内部的一瞥。它发出的光强度是CO的两倍，其次是SO，强度仅稍强于CO。相比之下，重金属转子（例如HCOOCH3，CH3CH2CN和CH3OCH3）发出的线数最多，但它们对总通量的贡献是不重要。CH3OH在生产线数和总通量方面也非常突出。这项调查的一个有趣的细节是首次检测到在高于地面2000 K的v2 = 2状态下的振动激发的HCN。显然，这是Orion热核内部的一瞥。它发出的光强度是CO的两倍，其次是SO，强度仅稍强于CO。相比之下，重金属转子（例如HCOOCH3，CH3CH2CN和CH3OCH3）发出的线数最多，但它们对总通量的贡献是不重要。CH3OH在生产线数和总通量方面也非常突出。这项调查的一个有趣的细节是首次检测到在高于地面2000 K的v2 = 2状态下的振动激发的HCN。显然，这是Orion热核内部的一瞥。行数和积分通量都一样。这项调查的一个有趣的细节是首次检测到在高于地面2000 K的v2 = 2状态下的振动激发的HCN。显然，这是Orion热核内部的一瞥。行数和积分通量都一样。这项调查的一个有趣的细节是首次检测到在高于地面2000 K的v2 = 2状态下的振动激发的HCN。显然，这是Orion热核内部的一瞥。