J/MNRAS/466/2948ivo://CDS.VizieR/J/MNRAS/466/2948doi:10.26093/cds/vizier.74662948CDSAkras S.Ramirez Velez J.C.Nanouris N.Ramos-larios G.Lopez J.M.,Hiriart D.Panoglou D.2024-08-17T20:17:49Z2019-11-27T14:50:14ZCDS support team

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

cds-question@unistra.frgiant-starspolarimetryWe present new optical broad-band (UBVRI) aperture polarimetric observations of 53 post-asymptotic giant branch (AGB) stars selected to exhibit a large near-infrared excess. 24 out of the 53 stars (45% of our sample) are presented for the first time. A statistical analysis shows four distinctive groups of polarized post-AGB stars: unpolarized or very lowly polarized (degree of polarization or DoP<1%), lowly polarized (1%<DoP<4%), moderately polarized (4%<DoP<8%) and highly polarized (DoP>8%). 23 out of the 53 (66%) belong to the first group, 10 (19%) to the second, five ( %) to the third and only three (6%) to the last group. Approximately 34%of our sample was found to be unpolarized objects, which is close to the percentage of round planetary nebulae. On average, the low and moderate groups show a wavelength-dependent polarization that increases towards shorter wavelengths, implying an intrinsic origin of the polarization, which signifies a Rayleigh-like scattering spectrum typical for non-symmetrical envelopes composed principally of small dust grains. The moderately polarized stars exhibit higher K-W3 and W1-W3 colour indices compared with the group of lowly polarized stars, suggesting a possible relation between DoP and mass-loss rate. Moreover, they are found to be systematically colder (redder in B-V), which may be associated with the condensation process close to these stars that results in a higher degree of polarization. We also provide evidence that multiple scattering in optically thin polar outflows is the mechanism that gives high DoP in post-AGB stars with bipolar or multi-polar envelopes.2017MNRAS.466.2948Ahttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/466/2948CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/469/799 : Torun catalog of post-AGB and related objects (Szczerba+, 2007)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/466/2948https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/466/2948http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/466/2948https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/466/2948https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/466/2948http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/466/2948GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/466/2948/table1 (Log file of the observations)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/466/2948/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/466/2948/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/466/2948/table1?GETtext/xml+votable180.050000true36.6737562.3561110.0055555555555555566/1096 1229 1352 1813 3333 3649 4361 5966 7064 9713 12851 12948 13046 13187 13729 13917 14040 14248 14253 14256 14425 14440 14450 14453 14480 14918 14929 18436 20921 21090 21326 21931 22392 22425 22450 23660 23707 24079 24394 25501 25993 29869 30127 30297 30498 30591 31766 31889 32181 32543 32562 40555 48822https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/466/2948?format=asciidefaultJ/MNRAS/466/2948/table1Log file of the observationsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintPolindicates polarization measurements in table B1meta.ref.urlcharNameName (mainly IRAS name)meta.id;meta.maincharprimaryONameOther namemeta.idcharGLONGalactic longitudedegpos.galactic.lonGLATGalactic latitudedegpos.galactic.latfloatRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainTypeTypesrc.classcharBinNote on binaritymeta.notecharRefReference (1)meta.ref;pos.framecharSimbadSimbad column added by the CDSmeta.ref.urlcharJ/MNRAS/466/2948/tableb1Intrinsic degree of polarization, PA of the polarization vectors, total degree of polarization and ISP of all the stars in our samplerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameNamemeta.id;meta.maincharPAISPIntrinsic degree of polarizationdegpos.posAng;phys.polarizationfloate_PAISPrms uncertainty on PAISPdegstat.errorfloatJDJulian date (JD-2450000)dtime.epochdoubleFiltFiltermeta.id;instr.filtercharDoP? Polarization degree corrected for the ISM and bias noise%phys.polarizationfloatnullablee_DoP? rms uncertainty on DoP%stat.errorfloatnullablePA? Position angle corrected for the ISM and bias noisedegpos.posAng;phys.polarizationfloatnullablee_PA? rms uncertainty on PAdegstat.errorfloatnullablePMASObserved polarization degree measurements after correction for the bias noise%phys.polarizationfloate_PMASrms uncertainty on PMAS%stat.errorfloatPobsObserved polarization degree measurements before correction for the bias noise%arith.factor;phys.polarizationfloate_Pobsrms uncertainty on Pobs%stat.errorfloatPAobsObserved position angledegpos.posAng;phys.polarizationfloate_PAobsrms uncertainty on PAobsdegstat.errorfloatISPInterstellar degree of polarization%phys.polarizationfloate_ISPrms uncertainty on ISP%stat.errorfloat