title: Revised spectroscopic parameters of SH(+) from ALMA and IRAM 30m observations.
abstract: Hydrides represent the first steps of interstellar chemistry. Sulfanylium (SH(+)), in particular, is a key tracer of energetic processes. We used ALMA and the IRAM 30 m telescope to search for the lowest frequency rotational lines of SH(+) toward the Orion Bar, the prototypical photo-dissociation region illuminated by a strong UV radiation field. On the basis of previous Herschel/HIFI observations of SH(+), we expected to detect emission of the two SH(+) hyperfine structure (HFS) components of the NJ = 10-01 fine structure (FS) component near 346 GHz. While we did not observe any lines at the frequencies predicted from laboratory data, we detected two emission lines, each ~15 MHz above the SH(+) predictions and with relative intensities and HFS splitting expected for SH(+). The rest frequencies of the two newly detected lines are more compatible with the remainder of the SH(+) laboratory data than the single line measured in the laboratory near 346 GHz and previously attributed to SH(+). Therefore, we assign these new features to the two SH(+) HFS components of the NJ = 10-01 FS component and re-determine its spectroscopic parameters, which will be useful for future observations of SH(+), in particular if its lowest frequency FS components are studied. Our observations demonstrate the suitability of these lines for SH(+) searches at frequencies easily accessible from the ground.
authors.affiliation: I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany, hspm@ph1.uni-koeln.de.
authors.forename: Holger S P
authors.initials: HS
authors.lastname: Müller
authors.affiliation: Instituto de Ciencias de Materiales de Madrid (CSIC), 28049 Cantoblanco, Madrid, Spain.
authors.forename: Javier R
authors.initials: JR
authors.lastname: Goicoechea
authors.affiliation: Instituto de Ciencias de Materiales de Madrid (CSIC), 28049 Cantoblanco, Madrid, Spain.
authors.forename: José
authors.initials: J
authors.lastname: Cernicharo
authors.affiliation: Instituto de Ciencias de Materiales de Madrid (CSIC), 28049 Cantoblanco, Madrid, Spain.
authors.forename: Marcelino
authors.initials: M
authors.lastname: Agúndez
authors.affiliation: IRAM, 300 rue de la Piscine, 38406 Saint Martin d'Hères, France ; CNRS UMR 8112, LERMA, Observatoire de Paris, École Normale Supérieure and Université Pierre et Marie Curie, 75014 Paris, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Pety
authors.affiliation: Instituto de Ciencias de Materiales de Madrid (CSIC), 28049 Cantoblanco, Madrid, Spain ; Centro de Astrobiología (CSIC-INTA), Carretera de Ajalvir km 4, 28850 Torrejón de Ardoz, Madrid, Spain.
authors.forename: Sara
authors.initials: S
authors.lastname: Cuadrado
authors.affiliation: CNRS UMR 8112, LERMA, Observatoire de Paris, École Normale Supérieure and Université Pierre et Marie Curie, 75014 Paris, France.
authors.forename: Maryvonne
authors.initials: M
authors.lastname: Gerin
authors.affiliation: IRAM, 300 rue de la Piscine, 38406 Saint Martin d'Hères, France.
authors.forename: Gaëlle
authors.initials: G
authors.lastname: Dumas
authors.affiliation: IRAM, 300 rue de la Piscine, 38406 Saint Martin d'Hères, France ; CNRS, LAB, UMR 5804, 33270 Floirac, France ; Université de Bordeaux, LAB, UMR 5804, 33270 Floirac, France.
authors.forename: Edwige
authors.initials: E
authors.lastname: Chapillon
keywords: ISM – ISM; Orion Bar; identification – ISM; individual objects; molecular data – line; molecules – radio lines