The spectrum of Orion-KL at 2 millimeters (150-160 GHz)

L. M. Ziurys, Douglas Mcgonagle

Research output: Contribution to journalArticle

53 Scopus citations

Abstract

A spectral survey of Orion-KL has been carried out in the 2 mm atmospheric window in the frequency range 149.6-159.6 GHz, using the FCRAO 14 m telescope. Typical sensitivities achieved were TA* ∼ 0.03-0.1 K, peak-to-peak. Over 180 spectral lines were detected, including ∼45 unidentified features. The spectra were measured with a single-sideband receiver and, even at levels of TA* ∼ 30 mK, are far from being confusion-limited. Fifteen known species were conclusively identified in Orion in this spectral region, with the largest numbers of lines arising from methyl formate, ethyl cyanide, methanol, and dimethyl ether. These species have beam-averaged column densities of Ntot ∼ 0.5-8 × 1015 cm-2. Several other species have been tentatively observed, including acetaldehyde, C2S, and possibly EtOH. The large organic species, however, appear to arise from different regions. For example, CH3CCH and (CH3)2O come primarily from the extended ridge, while EtCN and VyCN exclusively arise in the hot core. This survey clearly demonstrates that the 2 mm window is rich in spectral lines. It also suggests there is much chemical selectivity in the formation of large organic interstellar molecules.

Original languageEnglish (US)
Pages (from-to)155-187
Number of pages33
JournalAstrophysical Journal, Supplement Series
Volume89
Issue number1
DOIs
StatePublished - Jan 1 1993
Externally publishedYes

Keywords

  • ISM: individual (Orion-KL)
  • ISM: molecules
  • Line: identification
  • Radio line: molecular: interstellar

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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