Millimetre and submillimetre spectroscopy of isobutene and its detection in the molecular cloud G+0.693
arXiv:2309.17236 · doi:10.1051/0004-6361/202347112
Abstract
Isobutene ((CH)C=CH) is one of the four isomers of butene (CH). Given the detection of propene (CHCH=CH) toward TMC-1, and also in the warmer environment of the solar-type protostellar system IRAS 162932422, one of the next alkenes, isobutene, is a promising candidate to be searched for in space. We aim to extend the limited line lists of the main isotopologue of isobutene from the microwave to the millimetre region in order to obtain a highly precise set of rest frequencies and to facilitate its detection in the interstellar medium. We investigated the rotational spectrum of isobutene in the 35370 GHz range using absorption spectroscopy at room temperature. Quantum-chemical calculations were carried out to evaluate vibrational frequencies. We determined new or improved spectroscopic parameters for isobutene up to a sixth-order distortion constant. These new results enabled its detection in the G+0.693 molecular cloud for the first time, where propene was also recently found. The propene to isobutene column density ratio was determined to be about 3:1. The observed spectroscopic parameters for isobutene are sufficiently accurate that calculated transition frequencies should be reliable up to 700 GHz. This will further help in observing this alkene in other, warmer regions of the ISM.
11 pages including figures, tables, references, and appendix; Accepted for publication in Astronomy and Astrophysics
References in corpus (26)
- 2021 Census of Interstellar, Circumstellar, Extragalactic, Protoplanetary Disk, and Exoplanetary Molecules
- Detection of a branched alkyl molecule in the interstellar medium: iso-propyl cyanide
- The largest oxigen bearing organic molecule repository
- Discovery of Interstellar Propylene (CH_2CHCH_3): Missing Links in Interstellar Gas-Phase Chemistry
- Tracing shocks and photodissociation in the Galactic center region
- Spectral Line Identification and Modelling (SLIM) in the MAdrid Data CUBe Analysis (MADCUBA) package: An interactive software for data cube analysis
- Discovery in space of ethanolamine, the simplest phospholipid head group
- A New Reference Chemical Composition for TMC-1
- Thiols in the ISM: first detection of HC(O)SH and confirmation of CHSH
- Prebiotic precursors of the primordial RNA world in space: Detection of NHOH
- Cloud-cloud collision as drivers of the chemical complexity in Galactic Centre molecular clouds
- Discovery of CH2CHCCH and detection of HCCN, HC4N, CH3CH2CN, and, tentatively, CH3CH2CCH in TMC-1
- Probing the chemical complexity of amines in the ISM: detection of vinylamine (CHNH) and tentative detection of ethylamine (CHNH)
- Precursors of fatty alcohols in the ISM: Discovery of n-propanol
- Propargylimine in the laboratory and in space: millimetre-wave spectroscopy and first detection in the ISM
- The ALMA-PILS survey: First detection of the unsaturated 3-carbon molecules Propenal (CHCHO) and Propylene (CH) towards IRAS 162932422 B
- First detection of CHNCO in the ISM and search of other isocyanates towards the G+0.693-0.027 molecular cloud
- Detection of Interstellar HCO in TMC-1 with the Green Bank Telescope
- Detection of the cyanomidyl radical (HNCN): a new interstellar species with the NCN backbone
- Space and laboratory observation of the deuterated cyanomethyl radical HDCCN
- Interstellar detection and chemical modeling of iso-propanol and its normal isomer
- Toward the limits of complexity of interstellar chemistry: Rotational spectroscopy and astronomical search for n- and i-butanal
- CH3-Terminated Carbon Chains in the GOTHAM Survey of TMC-1: Evidence of Interstellar CH3C7N
- Discovery of five cyano derivatives of propene with the QUIJOTE line survey
- LLWP -- A new Loomis-Wood Software at the Example of Acetone-13C1
- Rotational spectroscopy of isotopic oxirane, -CHO