AMBER/VLTI and MIDI/VLTI spectro-interferometric observations of the B[e] supergiant CPD-57\deg2874. Size and geometry of the circumstellar envelope in the near- and mid-IR
Domiciano de Souza, A; Driebe, T; Chesneau, O; et al.Hofmann, K-H; Kraus, S; Miroshnichenko, AS; Ohnaka, K; Petrov, RG; Preisbisch, T; Stee, P; Weigelt, G; Lisi, F; Malbet, F; Richichi, A
Date: 20 February 2007
Journal
Astronomy and Astrophysics
Publisher
EDP Sciences
Publisher DOI
Abstract
We present the first high spatial and spectral resolution 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 ...
We present the first high spatial and spectral resolution 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 1.8 × 3.4 mas or 4.5 × 8.5 AU (adopting
a distance of 2.5 kpc) at 2.2 µm, and 12 × 15 mas or 30 × 38 AU at 12 µm. The size of the region emitting the Brγ flux is
2.8 × 5.2 mas or 7.0 × 13.0 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.
Physics and Astronomy
Faculty of Environment, Science and Economy
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