Speckle-masking imaging polarimetry of η Carinae: Evidence for an equatorial disk

H. Falcke, Kris Davidson, K. H. Hofmann, G. Weigelt

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Abstract

With our new speckle imaging polarimeter we have obtained the first polarimetric images with sub-arcsecond resolution of the Luminous Blue Variable η Carinae in the Ha line. The polarization patterns at the 3" scale match well earlier conventional imaging photometry and can be interpreted as Mie scattering. In crosscorrelation-centered images we detected in polarized light a bar in the NE part of the equatorial plane of η Carinae. High-resolution 0.11" polarimetric speckle reconstructions reveal a compact structure elongated in the same direction which is consistent, in degree and position angle of the polarisation, with the presence of a circumstellar, equatorial disk. The degree of polarization of the previously discovered speckle objects and the Hα arm is relatively low (∼ 10%) and thus may indicate a position within the equatorial plane. We also discovered a highly polarized (20% - 40%) bipolar structure along the major axis of the Homunculus nebula which can be traced down to the sub-arcsecond scale. This is probably the inner part of a bipolar outflow into the Homunculus.

Original languageEnglish (US)
JournalAstronomy and Astrophysics
Volume306
Issue number1
StatePublished - Feb 1 1996

Keywords

  • Circumstellar matter
  • Stars: imaging
  • Stars: individual: Eta Carinae
  • Techniques: polarimetric

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    Falcke, H., Davidson, K., Hofmann, K. H., & Weigelt, G. (1996). Speckle-masking imaging polarimetry of η Carinae: Evidence for an equatorial disk. Astronomy and Astrophysics, 306(1).