J/A+A/470/191ivo://CDS.VizieR/J/A+A/470/191doi:10.26093/cds/vizier.34700191CDSWittkowski M.Boboltz D.A.Ohnaka K.Driebe T.Scholz M.2017-06-12T08:24:37Z2007-10-28T08:38:09ZCDS support team

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

cds-question@unistra.frinterferometryastrophysical-masersradio-astronomyinfrared-astronomyspectroscopyWe present the first multi-epoch study that includes concurrent mid-infrared and radio interferometry of an oxygen-rich Mira star. We obtained mid-infrared interferometry of S Ori with VLTI/MIDI at four epochs in December 2004, February/March 2005, November 2005, and December 2005. We concurrently observed v=1, J=1-0 (43.1GHz) and v=2, J=1-0 (42.8GHz) SiO maser emission toward S Ori with the VLBA in January, February, and November 2005. The MIDI data are analyzed using self-excited dynamic model atmospheres including molecular layers, complemented by a radiative transfer model of the circumstellar dust shell. The VLBA data are reduced to the spatial structure and kinematics of the maser spots. The modeling of our MIDI data results in phase-dependent continuum photospheric angular diameters of 9.0+/-0.3mas (phase 0.42), 7.9+/-0.1mas (0.55), 9.7+/-0.1mas (1.16), and 9.5+/-0.4mas (1.27). The dust shell can best be modeled with Al2O3 grains alone using phase-dependent inner boundary radii between 1.8 and 2.4 photospheric radii. The dust shell appears to be more compact with larger optical depth near visual minimum (tau_V_~2.5), and more extended with lower optical depth after visual maximum (tau_V_~1.5). The ratios of the 43.1GHz/42.8GHz SiO maser ring radii to the photospheric radii are 2.2+/-0.3/2.1+/-0.2 (phase 0.44), 2.4+/-0.3/2.3+/-0.4 (0.55), and 2.1+/-0.3/1.9+/-0.2 (1.15). The maser spots mark the region of the molecular atmospheric layers shortly outward of the steepest decrease of the mid-infrared model intensity profile. Their velocity structure indicates a radial gas expansion. S Ori shows significant phase-dependences of photospheric radii and dust shell parameters. Al2O3 dust grains and SiO maser spots form at relatively small radii of ~1.8-2.4 photospheric radii. Our results suggest increased mass-loss and dust formation close to the surface near minimum visual phase, when Al2O3 dust grains are co-located with the molecular gas and the SiO maser shells, and a more expanded dust shell after visual maximum. Silicon does not appear to be bound in dust, as our data shows no sign of silicate grains.2007A&A...470..191Whttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/470/191CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/470/191https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/470/191http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/470/191https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/470/191https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/470/191http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/470/191GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapInfraredRadiodefaultJ/A+A/470/191/tablea1Calibrated MIDI visibility and flux data from 4 epochsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEpoch[A-D] Epoch of observationtime.epoch;obscharObsDate of observationstime.epochnullablelambdaCentral Wavelengthumem.wl.centralfloatuSpatial frequency uarcsec**-1obs.paramfloatvSpatial frequency varcsec**-1obs.paramfloatVampVisibility Amplitude Vobs.paramfloate_VampError of Vampstat.errorfloatfnuTotal flux at lambdaJyphot.flux.density;em.IRfloate_fnuError of fnuJystat.errorfloatJ/A+A/470/191/SiOSiO maser characteristics derived from the VLBA data at 3 different epochsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEpSimbad column added by the CDSmeta.notecharv[v=12] Maser transition (1)phys.atmol.qncharvLSRLSR velocitykm/sphys.veloc;pos.lsrfloatSnuFlux (in Jy/beam)Jyphot.flux.density;em.mm.30-50GHzfloate_SnuError of Snu (in Jy/beam)Jystat.errorfloatoRAOffset in Right ascensionmaspos.eq.ra;arith.difffloate_oRAError of ORAmasstat.errorfloatoDEOffset in Declinationmaspos.eq.dec;arith.difffloate_oDEError of ODEmasstat.errorfloat