J/ApJ/728/149ivo://CDS.VizieR/J/ApJ/728/149doi:10.26093/cds/vizier.17280149CDSVlemmings W.H.T.Humphreys E.M.L.Franco-Hernandez R.2012-11-07T21:46:17Z2012-10-22T13:08:48ZCDS support team

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

cds-question@unistra.frastrophysical-masersradio-astronomypolarimetrylate-type-starsWe present Submillimeter Array observations of high-frequency SiO masers around the supergiant VX Sgr and the semi-regular variable star W Hya. The J=5-4, v=1^28^SiO and v=0^29^SiO masers of VX Sgr are shown to be highly linearly polarized with a polarization from ~5% to 60%. Assuming the continuum emission peaks at the stellar position, the masers are found within ~60mas of the star, corresponding to ~100AU at a distance of 1.57kpc. The linear polarization vectors are consistent with a large-scale magnetic field, with position and inclination angles similar to that of the dipole magnetic field inferred in the H_2_O and OH maser regions at much larger distances from the star. We thus show for the first time that the magnetic field structure in a circumstellar envelope can remain stable from a few stellar radii out to ~1400AU. This provides further evidence supporting the existence of large-scale and dynamically important magnetic fields around evolved stars. Due to a lack of parallactic angle coverage, the linear polarization of masers around W Hya could not be determined. For both stars, we observed the ^28^SiO and ^29^SiO isotopologues and find that they have a markedly different distributions and that they appear to avoid each other. Additionally, emission from the SO 5_5_-4_4_ line was imaged for both sources. Around W Hya, we find a clear offset between the red- and blueshifted SO emission. This indicates that W Hya is likely host to a slow bipolar outflow or a rotating disk-like structure.2011ApJ...728..149Vhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/728/149CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toV/68 : Stellar Maser Observations (Benson+ 1990)V/18 : Catalogue of Late-type Stars with Maser Emission (Engels, 1979)J/A+A/524/A99 : Polarisation of S Per and VX Sgr in OH (Szymczak+, 2010)J/ApJ/640/982 : 43GHz SiO maser features around VX Sgr (Chen+, 2006)J/A+A/434/201 : The 35um absorption line towards 1612MHz masers (He+, 2005)J/AJ/123/2772 : OH-selected AGB and post-AGB objects. I. (Sevenster+, 2002)J/PASJ/53/517 : Water maser survey of late-type stars (Takaba+, 2001)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/728/149https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/728/149http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/728/149https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/728/149https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/728/149http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/728/149GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/728/149/table1 (Polarized SiO masers of VX Sgr)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/728/149/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/728/149/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/728/149/table1?GETtext/xml+votable180.050000true272.01693667-22.224567220.0055555555555555566/28917https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/728/149?format=asciiRadiodefaultJ/ApJ/728/149/table1Polarized SiO masers of VX SgrrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObs[1/2] SiO maser observation type (1)meta.noteintVLSRLocal Standard of Rest velocitykm/sphys.veloc;pos.lsrfloatoRAOffset in Right Ascension (2)maspos.eq.ra;arith.difffloate_oRAUncertainty in oRAmasstat.errorfloatoDEOffset in Declination (2)maspos.eq.dec;arith.difffloate_oDEUncertainty in oDEmasstat.errorfloatS0Average brightness; Jy/beamJyphot.flux.density;em.radiofloatE_S0Upper limit uncertainty in S0Jystat.error;stat.maxfloate_S0Lower limit uncertainty in S0Jystat.errorfloatSpPolarized brightness; Jy/beamJyphot.flux.densityfloatE_SpUpper limit uncertainty in SpJystat.error;stat.maxfloate_SpLimit limit uncertainty in SpJystat.error;src.spTypefloatchiElectric-vector position angledegpos.posAngintE_chiUpper limit uncertainty in chidegstat.error;stat.maxinte_chiLower limit uncertainty in chidegstat.errorintPlFractional linear polarization%phys.polarization.linearint_RAPosition computed from offsets oRA, oDE, with center at 18:08:04.068-22:13:28.416 (right ascension part)degpos.eq.ra;meta.main_DEPosition computed from offsets oRA, oDE, with center at 18:08:04.068-22:13:28.416 (declination part)degpos.eq.dec;meta.main