J/A+A/628/A132ivo://CDS.VizieR/J/A+A/628/A132doi:10.26093/cds/vizier.36280132CDSAdam C.Ohnaka K.2019-11-27T13:20:29Z2019-08-26T08:21:19ZCDS support team

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

cds-question@unistra.frsupergiant-starslate-type-starsastronomical-modelsstellar-atmospheresstellar-mass-losspolarimetryinterferometryWe present visible polarimetric imaging observations of the oxygen-rich AGB star IK Tau obtained with SPHERE-ZIMPOL (phase 0.27) as well as interferometric observations with AMBER. The polarimetric imaging capabilities of SPHERE-ZIMPOL have allowed us to spatially resolve clumpy dust clouds at 20-50mas from the central star, which corresponds to 2-5R* when combined with a central star's angular diameter of 20.7+/-1.53 mas measured with AMBER. The diffuse, asymmetric dust emission extends out to ~73R*. We find that the TiO emission extends to 150 mas (15R*). The AMBER data in the CO lines also suggest a molecular outer atmosphere extending to ~1.5R*. The results of our 2-D Monte Carlo radiative transfer modelling of dust clumps suggest that the polarized intensity and degree of linear polarization can be reasonably explained by small-sized (0.1{mu}m) grains of Al_2_O_3, MgSiO_3, or Mg_2_SiO_4 in an optically thin shell ({tau}_550 nm=0.5+/-0.1) with an inner boundary radius of 3.5*. IK Tau's mass-loss rate is 20 to 50 times higher than the previously studied AGB stars W Hya, R Dor, and o Cet. Nevertheless, our observations of IK Tau revealed that clumpy dust formation occurs close to the star as seen in those low mass-rate AGB stars.2019A&A...628A.132Ahttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/628/A132CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/597/A25 : IK Tau millimeter IRAM-30m line survey (Velilla Prieto+, 2017)J/A+A/624/A107 : IK Tau + IRC+10011 interferometric obs. (Verbena+, 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/628/A132https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/628/A132http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/628/A132https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/628/A132https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/628/A132http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/628/A132GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/628/A132/list (List of FITS files)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/628/A132/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/628/A132/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/628/A132/list?GETtext/xml+votable180.050000true64.90583310.1213890.0055555555555555566/23452 23471https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/628/A132?format=asciidefaultJ/A+A/628/A132/listList of FITS filesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination sign (J2000)pos.eq.dec;meta.mainscaleScale of the imagearcsec/pixinstr.scaledoubleNxNumber of pixels along X-axismeta.numberintNyNumber of pixels along Y-axismeta.numberintlambda[0.645/0.820] ZIMPOL filter (wavelength)umem.wlfloatFilterName of ZIMPOL filtermeta.id;instr.filtercharDIT[2/80] Detector integration timestime.epoch;instr.detintObsModeObservation mode (1)instr.setup;obscharsizeSize of FITS fileKibytephys.size;meta.fitsintFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitscharTitleTitle of the filemeta.title;meta.filecharJ/A+A/628/A132/visiktauObserved visibilities and closure phases for IK Tau observed with VLT/AMBERrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelengthumem.wldoubleF1Flux measured at baseline 1 (1)phot.fluxdoubleVis1Visibility at baseline 1meta.notedoublee_Vis1Visibility uncertainty at baseline 1stat.errordoubleDP1Differential phase at baseline 1degtime.phase;arith.diffdoublee_DP1Differential phase uncertainty at baseline 1degstat.errordoubleVis2Visibility at baseline 2meta.notedoublee_Vis2Visibility uncertainty at baseline 2stat.errordoubleDP2Differential phase at baseline 2degtime.phase;arith.diffdoublee_DP2Differential phase uncertainty at baseline 2degstat.errordoubleVis3Visibility at baseline 3meta.notedoublee_Vis3Visibility uncertainty at baseline 3stat.errordoubleDP3Differential phase at baseline 3degtime.phase;arith.diffdoublee_DP3Differential phase uncertainty at baseline 3degstat.errordoubleCPClosure phasedegtime.phasedoublee_CPClosure phase uncertaintydegstat.errordouble