VLTI/AMBER and VLTI/MIDI spectro-interferometric observations of
the B[e] supergiant CPD-57 2874
A. Domiciano de Souza1,
T. Driebe1,
O. Chesneau2,
K.-H. Hofmann1,
S. Kraus1,
A. S. Miroshnichenko1,3,
K. Ohnaka1,
R. G. Petrov1,
Th. Preibisch1,
P. Stee2,
G. Weigelt1,
F. Lisi5,
F. Malbet6, and
A. Richichi7
1
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
2
Observatoire de la Côte d'Azur, Gemini, CNRS UMR 6203, Avenue
Copernic, 06130 Grasse, France
3
Dept. of Physics and Astronomy, P.O. Box 26170, University of
North Carolina at Greensboro, Greensboro, NC 27402-6170, USA
4
Laboratoire Universitaire d'Astrophysique de Nice (LUAN),
CNRS UMR 6525, UNSA, Parc Valrose, 06108 Nice, France
5
INAF-Osservatorio Astrofisico di Arcetri, Istituto Nazionale di
Astrofisica, Largo E. Fermi 5, I-50125 Firenze, Italy
6
Laboratoire d'Astrophysique de Grenoble, UMR 5571 Université
Joseph Fourier/CNRS, BP 53, 38041 Grenoble Cedex 9, France
7
European Southern Observatory, Karl Schwarzschild Strasse 2,
85748 Garching, Germany
We present the first high spatial and
spectral observations of the circumstellar envelope (CSE) of a
B[e] supergiant (CPD-57 2874), performed with the Very Large
Telescope Interferometer (VLTI). Spectra, visibilities, and
closure phase, were obtained using the beam-combiner instruments
AMBER (near-IR interferometry with three 8.3 m Unit Telescopes or
UTs) and MIDI (mid-IR interferometry with two UTs). The
interferometric observations of the CSE are well fitted by an
elliptical Gaussian model with FWHM diameters varying linearly
with wavelength. Typical diameters measured are
 1.8x3.4 mas or
4.5x8.5 AU
(adopting a distance of 2.5 kpc) at 2.2µm, and
12x15 mas or
30x38 AU at 12µm.
The size of the region
emitting the Br flux is
2.8x5.2 mas or
7.0x13.0 AU. The major-axis position angle of the
elongated CSE in the mid-IR ( 144°) agrees well with
previous polarimetric data, hinting that the hot-dust emission
originates in a disk-like structure. In addition to the
interferometric observations we also present new optical
(UBVRcIc) and near-IR (JHKL) broadband photometric
observations of CPD-57 2874. Our spectro-interferometric VLTI
observations and data analysis support the non-spherical CSE
paradigm for B[e] supergiants.
Accepted by A&A
Preprints from
Armando.Domiciano@unice.fr
or on the web at
http://arxiv.org/abs/astro-ph/0510735
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