Publications of the MPIfR
Optical & Infrared
Interferometry Group
A. Domiciano de Souza, T. Driebe, O.
Chesneau, K.-H. Hofmann, S. Kraus, A.S. Miroshnichenko, K. Ohnaka, R.G.
Petrov,
Th. Preibisch, P. Stee, G. Weigelt
The vicinity of the galactic supergiant B[e]
star CPD-57° 2874 from near- and mid-IR long baseline
spectro-interferometry with
the VLTI (AMBER and MIDI)
Workshop on "Stars with the B[e] phenomenon"
July 10-16, 2005 in Vlieland, the Netherlands
ASP Conference Series, Vol.355, pg.155-161 (2006)
Abstract
We present the first spectro-interferometric observations of the cir-
cumstellar envelope (CSE) of a B[e] supergiant (CPD°57± 2874),
performed with
the Very Large Telescope Interferometer (VLTI) using the beam-combiner
in-
struments AMBER (near-IR interferometry with three 8.3 m Unit
Telescopes or
UTs) and MIDI (mid-IR interferometry with two UTs). Our observations of
the
CSE are well fitted by an elliptical Gaussian model with FWHM diameters
vary-
ing linearly with wavelength. Typical diameters measured are ≅1.8
x 3.4 mas
or ≅4.5
x 8.5 AU (adopting a distance of 2.5 kpc) at 2.2 µm, and ≅12
x 15 mas
or ≅30
x 38 AU at 12 µm. We show that a spherical dust model reproduces
the SED but it underestimates the MIDI visibilities, suggesting that a
dense
equatorial disk is required to account for the compact dust-emitting
region ob-
served. Moreover, the derived major-axis position angle in the mid-IR (
≅144°)
agrees well with previous polarimetric data, hinting that the hot-dust
emission
originates in a disk-like structure. Our results support the
non-spherical CSE
paradigm for B[e] supergiants.
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