A spectral survey of the Star Forming Core of the Orion Nebula from 455 -- 507 GHz

TL;DR

This spectral survey of the Orion-KL hot core in the 455-507 GHz range detected 254 lines from 30 molecular species, revealing complex organic molecules and physical conditions, advancing understanding of star-forming regions.

Contribution

First comprehensive submillimetre spectral line survey of Orion-KL in this frequency range, identifying molecular composition and physical parameters of the core.

Findings

Detected 254 spectral lines from 30 molecules.

Dominance of complex organic molecules like CH3CN and HCOOCH3.

Rotational temperatures range from 70 to 300 K.

Abstract

The results of a submillimetre wavelength spectral line survey between 455.1 -- 507.4 GHz of the Orion-KL hot cloud core are reported. A total of 254 lines were detected to a main beam brightness temperature sensitivity ~ 1 - 3 K. The detected lines are identified as being associated with 30 different molecular species or their isotopomeric variants. The strongest line detected was the J = 4-3 transition of the CO molecule. Apart from abundant diatomic rotors such as CO and CS, the spectrum is dominated by SO, SO_2 and CH_3OH and large organic molecules such as (CH_3)_2O, CH$_3CN, C_2H_3CN, C_2H_5CN and HCOOCH_3 which make up ~ 72% of the total number of lines; unidentified lines ~ 13%; and other lines the remaining ~ 15% of the total. Rotational temperatures and column densities derived using standard rotation diagram analysis techniques were found to range from 70 - 300 K, and 10^14 - 10^17 cm^2 respectively. Accepted by Astronomy & Astrophysics 22 May 2003