J/A+A/641/A57ivo://CDS.VizieR/J/A+A/641/A57doi:10.26093/cds/vizier.36410057CDSMassalkhi S.Agundez M.Cernicharo J.Velilla-Prieto L.2020-11-30T08:27:18Z2020-09-09T06:42:46ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frgiant-starsmolecular-physicsradio-spectroscopyWe aim to determine the abundances of SiO, CS, SiS, SO, and SO_2_ in a large sample of oxygen-rich asymptotic giant branch (AGB) envelopes covering a wide range of mass loss rates to investigate the potential role that these molecules could play in the formation of dust in these environments. We surveyed a sample of 30 oxygen-rich AGB stars in the {lambda} 2mm band using the IRAM 30m telescope. We performed excitation and radiative transfer calculations based on the large velocity gradient (LVG) method to model the observed lines of the molecules and to derive their fractional abundances in the observed envelopes. We detected SiO in all 30 targeted envelopes, as well as CS, SiS, SO, and SO 2 in 18, 13, 26, and 19 sources, respectively. Remarkably, SiS is not detected in any envelope with a mass loss rate below 10^-6^M_{sun}_/yr, whereas it is detected in all envelopes with mass loss rates above that threshold. From a comparison with a previous, similar study on C-rich sources, it becomes evident that the fractional abundances of CS and SiS show a marked differentiation between C-rich and O-rich sources, being two orders of magnitude and one order of magnitude more abundant in C-rich sources, respectively, while the fractional abundance of SiO turns out to be insensitive to the C/O ratio. The abundance of SiO in O-rich envelopes behaves similarly to C-rich sources, that is, the denser the envelope the lower its abundance. A similar trend, albeit less clear than for SiO, is observed for SO in O-rich sources. The marked dependence of CS and SiS abundances on the C/O ratio indicates that these two molecules form more efficiently in C- than O-rich envelopes. The decline in the abundance of SiO with increasing envelope density and the tentative one for SO indicate that SiO and possibly SO act as gas-phase precursors of dust in circumstellar envelopes around O-rich AGB stars.2020A&A...641A..57Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/641/A57CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+AS/97/729 : JHKL'M Observations of O-Rich late-type star (Le Bertre 1993)J/A+AS/107/445 : Envelopes of oxygen-rich AGB stars (Hashimoto, 1994)J/A+A/314/896 : IR fluxes & photometry of oxygen-rich stars (Le Sidaner+ 1996)J/A+AS/146/437 : IR spectra of oxygen-rich evolved stars (Speck+, 2000)J/A+A/572/A42 : SagDIG carbon and oxygen stars (Momany+, 2014)J/ApJ/794/81 : Oxygen-rich AGB stars maser & infrared studies (Yung+, 2014)J/A+A/626/A112 : Halo oxygen-rich AGB stars catalog (Mauron+, 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/641/A57https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/641/A57http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/641/A57https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/641/A57https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/641/A57http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/641/A57GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/641/A57/spectra (List of spectra available in oslines.fits file)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/641/A57/spectra?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/641/A57/spectra?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/641/A57/spectra?GETtext/xml+votable180.050000true58.370311.4060.005555555555555556Associated datahttps://cdsarc.cds.unistra.fr/assocdata/?obs_collection=J/A+A/641/A576/1889 1986 2732 3446 4355 5647 7152 8926 9074 9939 13813 16132 17716 18256 18364 18998 22434 23471 25246 26180 26327 26345 29963 30087 30244 31837 43890 44018 48038 48650https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/641/A57?format=asciiRadiodefaultJ/A+A/641/A57/spectraList of spectra available in oslines.fits filerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarStar namemeta.id;meta.maincharLineLinemeta.id;spect.linecharRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainspShow the spectrummeta.ref.urlchar