EDP Sciences
Free access
Volume 480, Number 2, March III 2008
Page(s) L29 - L32
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20079190

A&A 480, L29-L32 (2008)
DOI: 10.1051/0004-6361:20079190


High-resolution thermal infrared imaging of MWC300

VLT/VISIR observations in BURST mode
A. Domiciano de Souza1, P. Kervella2, P. Bendjoya1, and G. Niccolini1

1  Lab. H. Fizeau, CNRS UMR 6525, Univ. de Nice-Sophia Antipolis, Observatoire de la Côte d'Azur, 06108 Nice Cedex 2, France
    e-mail: Armando.Domiciano@unice.fr
2  LESIA, Observatoire de Paris, CNRS UMR 8109, UPMC, Université Paris Diderot, 5 place Jules Janssen, 92195 Meudon, France

(Received 4 December 2007 / Accepted 24 January 2008)

Context.B[e] stars are expected to possess dusty circumstellar environments, which are responsible for a strong infrared (IR) excess.
Aims.Using single-dish diffraction-limited imaging in the thermal infrared domain, we aim at measuring the angular extension of the dusty environment of the galactic B[e] MWC 300.
Methods.We obtained diffraction-limited images of MWC 300 at 11.25 $\mu$m using the BURST mode of the VLT/VISIR instrument.
Results.MWC 300 is partially, but statistically significantly, resolved by VISIR so that we could measure the size of its dusty envelope for the first time. By assuming a 2D circular Gaussian intensity distribution and using different image analysis methods we measured a FWHM angular size of 69 $\pm$ 10 mas. For a distance of 1.8 kpc, we obtain a linear size of 125$\pm$18 AU = (1.87$\pm$0.26) $\times$ 1013 m for the circumstellar dust emitting in the mid-IR. This measured size is shown to agree with a model that was calculated with our radiative radiative transfer code and constrained by previously reported SED data. Additionally, the flux of MWC 300 at 11.25 $\mu$m is estimated as 84.5$\pm$1.4 Jy = (20.0$\pm$0.3) $\times$ 10-13 W/m2/$\mu$m.
Conclusions.The VLT/VISIR now offers the possibility of obtaining mid-IR diffraction-limited images with a high signal-to-noise ratio. The MWC 300's size as directly measured in this work is compatible with the theoretical size of a nearly edge-on dusty disc estimated in previous works. Interferometric data at milliarcsec angular resolution are required to reveal details on this dusty envelope.

Key words: stars: individual: MWC300 -- methods: observational -- techniques: high angular resolution -- stars: emission-line, Be

© ESO 2008