J/A+A/617/A132ivo://CDS.VizieR/J/A+A/617/A132doi:10.26093/cds/vizier.36170132CDSDanilovich T.Ramstedt S.Gobrecht D.Decin L.De Beck E.Olofsson H.2018-12-03T15:07:49Z2018-10-01T09:16:39ZCDS support team

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

cds-question@unistra.frgiant-starsspectroscopySulphur has long been known to form different molecules depending on the chemical composition of its environment. More recently, the sulphur-bearing molecules SO and H2S have been shown to behave differently in oxygen-rich asymptotic giant branch (AGB) circumstellar envelopes of different densities. By surveying a diverse sample of AGB stars for CS and SiS emission, we aim to determine in which environments these sulphur-bearing molecules most readily occur. We include sources with a range of mass-loss rates and carbon-rich, oxygen-rich, and mixed S-type chemistries. Where these molecules are detected, we aim to determine their CS and SiS abundances. We surveyed 20 AGB stars of different chemical types using the APEX telescope, and combined this with an IRAM 30m and APEX survey of CS and SiS emission towards over 30 S-type stars. For those stars with detections, we performed radiative transfer modelling to determine abundances and abundance distributions. We detect CS towards all the surveyed carbon stars, some S-type stars, and the highest mass-loss rate oxygen-rich stars, (dM/dt>=5x10^-6^M_[sun}_/yr). SiS is detected towards the highest mass-loss rate sources of all chemical types (dM/dt>=8x10^-7^M_{sun}_/yr). We find CS peak fractional abundances ranging from ~4x10^-7^ to ~2x10^-5^ for the carbon stars, from ~3x10^-8^ to ~1x10^-7^ for the oxygen-rich stars, and from ~1x10^-7^ to ~8x10^-6^ for the S-type stars. We find SiS peak fractional abundances ranging from ~9x10^-6^ to ~2x10^-5^ for the carbon stars, from ~5x10^-7^ to ~2x10^-6^ for the oxygen-rich stars, and from ~2x10^-7^ to ~2x10^-^6 for the S-type stars. Overall, we find that wind density plays an important role in determining the chemical composition of AGB circumstellar envelopes. It is seen that for oxygen-rich AGB stars both CS and SiS are detected only in the highest density circumstellar envelopes and their abundances are generally lower than for carbon-rich AGB stars by around an order of magnitude. For carbon-rich and S-type stars SiS was also only detected in the highest density circumstellar envelopes, while CS was detected consistently in all surveyed carbon stars and sporadically among the S-type stars.2018A&A...617A.132Dhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/617/A132CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/617/A132https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/617/A132http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/617/A132https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/617/A132https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/617/A132http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/617/A132GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/617/A132/list (List of fits spectra)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/617/A132/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/617/A132/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/617/A132/list?GETtext/xml+votable180.050000true116.2600417-71.32941670.005555555555555556Associated datahttps://cdsarc.cds.unistra.fr/assocdata/?obs_collection=J/A+A/617/A1326/19112 21224 22434 23471 23606 26654 29877 29963 32062 37405 41204 41849https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/617/A132?format=asciidefaultJ/A+A/617/A132/listList of fits spectrarecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainNxNumber of pointsmeta.numberintbVelLower value of velocity intervalm/sspect.dopplerVelocdoubleBVelUpper value of velocity intervalm/sspect.dopplerVelocdoubledVelVelocity resolutionm/sspect.resolutiondoublesizeSize of FITS fileKibytephys.size;meta.fitsintStarStar namemeta.id;meta.maincharLineObserved linemeta.id;spect.linecharspShow the spectrummeta.ref.urlcharFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitscharAssocDataAssociated Data web pagemeta.bib.pagecharSimbadSimbad column added by the CDSmeta.ref.urlchar