IK Tau and HIP 20188 visible polarimetric imaging Virtual Observatory Resource

Authors
  1. Adam C.
  2. Ohnaka K.
  3. Published by
    CDS
Abstract

We 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.

Keywords
  1. Supergiant stars
  2. Late-type stars
  3. Astronomical models
  4. Stellar atmospheres
  5. Stellar mass loss
  6. Polarimetry
  7. Interferometry
Bibliographic source Bibcode
2019A&A...628A.132A
See also HTML
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/628/A132
IVOA Identifier IVOID
ivo://CDS.VizieR/J/A+A/628/A132
Document Object Identifer DOI
doi:10.26093/cds/vizier.36280132

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History

2019-08-26T08:21:19Z
Resource record created
2019-08-26T08:21:19Z
Created
2019-11-27T13:20:29Z
Updated

Contact

Name
CDS support team
Postal Address
CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France
E-Mail
cds-question@unistra.fr