Spectroscopic Characterization and Detection of Ethyl Mercaptan in Orion

New laboratory data of ethyl mercaptan, CH₃CH₂SH, in the millimeter- and submillimeter-wave domains (up to 880 GHz) provided very precise values of the spectroscopic constants that allowed the detection of gauche-CH₃CH₂SH toward Orion KL. This identification is supported by 77 unblended or slightly blended lines plus no missing transitions in the range 80-280 GHz. A detection of methyl mercaptan, CH₃SH, in the spectral survey of Orion KL is reported as well. Our column density results indicate that methyl mercaptan is sime 5 times more abundant than ethyl mercaptan in the hot core of Orion KL.

This work was based on observations carried out with the IRAM 30 m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).