Circumstellar Envelopes of OH/IR Stars

• We present VLTI observations of the tip-AGB star IRAS 17020-5254 carried out with the AMBER and MIDI instruments using the 1.8-m Auxiliary Telescopes (ATs) with three different baselines. This star is an evolved oxygen-rich single star of the OH/IR type. We fit the resulting near-infrared visibilities with a model consisting of a Gaussian component plus a central uniform disk, obtaining apparent diameters of the dust shell, the central star, and their flux ratios. We also show the uniform disk diameter as a function of wavelength from both the AMBER and MIDI observations. The mid-infrared diameter is about two to three times larger than the near-infrared one. We plan to compare these data to hydrodynamic atmosphere and wind models.

Ämnesord

NATURVETENSKAP  -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)

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