title: Detection of a noble gas molecular ion, 36ArH+, in the Crab Nebula.
abstract: Noble gas molecules have not hitherto been detected in space. From spectra obtained with the Herschel Space Observatory, we report the detection of emission in the 617.5- and 1234.6-gigahertz J = 1-0 and 2-1 rotational lines of (36)ArH(+) at several positions in the Crab Nebula, a supernova remnant known to contain both molecular hydrogen and regions of enhanced ionized argon emission. Argon-36 is believed to have originated from explosive nucleosynthesis in massive stars during core-collapse supernova events. Its detection in the Crab Nebula, the product of such a supernova event, confirms this expectation. The likely excitation mechanism for the observed (36)ArH(+) emission lines is electron collisions in partially ionized regions with electron densities of a few hundred per centimeter cubed.
authors: Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK.
authors: M J
authors: MJ
authors: Barlow
authors: B M
authors: BM
authors: Swinyard
authors: P J
authors: PJ
authors: Owen
authors: J
authors: J
authors: Cernicharo
authors: H L
authors: HL
authors: Gomez
authors: R J
authors: RJ
authors: Ivison
authors: O
authors: O
authors: Krause
authors: T L
authors: TL
authors: Lim
authors: M
authors: M
authors: Matsuura
authors: S
authors: S
authors: Miller
authors: G
authors: G
authors: Olofsson
authors: E T
authors: ET
authors: Polehampton