title: Discovery of SiCSi in IRC +10216: A missing link between gas and dust carriers of Si-C bonds.
abstract: We report the discovery in space of a disilicon species, SiCSi, from observations between 80 and 350 GHz with the IRAM 30m radio telescope. Owing to the close coordination between laboratory experiments and astrophysics, 112 lines have now been detected in the carbon-rich star CW Leo. The derived frequencies yield improved rotational and centrifugal distortion constants up to sixth order. From the line profiles and interferometric maps with the Submillimeter Array, the bulk of the SiCSi emission arises from a region of 6″ in radius. The derived abundance is comparable to that of SiC2. As expected from chemical equilibrium calculations, SiCSi and SiC2are the most abundant species harboring a Si-C bond in the dust formation zone and certainly both play a key role in the formation of SiC dust grains.
authors.affiliation: Group of Molecular Astrophysics. ICMM. CSIC. C/Sor Juana Inés de La Cruz N3. E-28049, Madrid. Spain.
authors.forename: J
authors.initials: J
authors.lastname: Cernicharo
authors.affiliation: Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, and School of Engineering & Applied Sciences, Harvard University, Cambridge, MA 02138.
authors.forename: M C
authors.initials: MC
authors.lastname: McCarthy
authors.affiliation: Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, and School of Engineering & Applied Sciences, Harvard University, Cambridge, MA 02138.
authors.forename: C A
authors.initials: CA
authors.lastname: Gottlieb
authors.affiliation: Group of Molecular Astrophysics. ICMM. CSIC. C/Sor Juana Inés de La Cruz N3. E-28049, Madrid. Spain.
authors.forename: M
authors.initials: M
authors.lastname: Agúndez
authors.affiliation: Group of Molecular Astrophysics. ICMM. CSIC. C/Sor Juana Inés de La Cruz N3. E-28049, Madrid. Spain.
authors.forename: L
authors.initials: L
authors.lastname: Velilla Prieto
authors.affiliation: Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309.
authors.forename: J H
authors.initials: JH
authors.lastname: Baraban
authors.affiliation: JILA, National Institute of Standards and Technology and University of Colorado, and Department of Physics, University of Colorado, Boulder, CO 80309.
authors.forename: P B
authors.initials: PB
authors.lastname: Changala
authors.affiliation: Institut de Radioastronomie Millimétrique, 300 rue de la Piscine, F-38406, St-Martin d'Hères, France.
authors.forename: M
authors.initials: M
authors.lastname: Guélin
authors.affiliation: Universit Grenoble Alpes, IPAG, F-38000 Grenoble, France; CNRS, IPAG, F-38000 Grenoble, France.
authors.forename: C
authors.initials: C
authors.lastname: Kahane
authors.affiliation: Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, and School of Engineering & Applied Sciences, Harvard University, Cambridge, MA 02138.
authors.forename: M A
authors.initials: MA
authors.lastname: Martin-Drumel
authors.affiliation: Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, and School of Engineering & Applied Sciences, Harvard University, Cambridge, MA 02138.
authors.forename: N A
authors.initials: NA
authors.lastname: Patel
authors.affiliation: Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, and School of Engineering & Applied Sciences, Harvard University, Cambridge, MA 02138.
authors.forename: N J
authors.initials: NJ
authors.lastname: Reilly
authors.affiliation: Institute for Theoretical Chemistry, Department of Chemistry, The University of Texas at Austin, Austin, TX 78712.
authors.forename: J F
authors.initials: JF
authors.lastname: Stanton
authors.affiliation: Group of Molecular Astrophysics. ICMM. CSIC. C/Sor Juana Inés de La Cruz N3. E-28049, Madrid. Spain.
authors.forename: G
authors.initials: G
authors.lastname: Quintana-Lacaci
authors.affiliation: I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Thorwirth
authors.affiliation: Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, and School of Engineering & Applied Sciences, Harvard University, Cambridge, MA 02138.
authors.forename: K H
authors.initials: KH
authors.lastname: Young
keywords: Stars: individual (IRC+10216); astrochemistry; stars: AGB and post-AGB; stars: carbon