Astronomy & Astrophysics

Issue		A&A Volume 469, Number 2, July II 2007
Page(s)		587 - 593
Section		Interstellar and circumstellar matter
DOI		10.1051/0004-6361:20066206

A&A 469, 587-593 (2007)
DOI: 10.1051/0004-6361:20066206

Resolving the B[e] star Hen 3-1191 at 10 $\mathsf{\mu}$ m with VLTI/MIDI

R. Lachaume^{1, 2}, Th. Preibisch², Th. Driebe², and G. Weigelt²

¹ Centro de Radioastronomía y Astrofísica UNAM, Apartado Postal 3-72 (Xangari), Morelia, CP 58089 Michoacán, Mexico
e-mail: r.lachaume@astrosmo.unam.mx
² Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany

(Received 7 August 2006 / Accepted 28 March 2007 )

Abstract
We report spatially resolved, spectrally dispersed N-band observations of the B[e] star Hen 3-1191 with the MIDI instrument of the Very Large Telescope Interferometer. The object is resolved with a 40 m baseline and has an equivalent uniform disc diameter ranging from 24 mas at 8 ${\mu{\rm m}}$ to 36 mas at 13 ${\mu{\rm m}}$ . The MIDI spectrum and visibilities show a curvature which can arise from a weak silicate feature in which the object appears $\approx$ 15% larger than in the continuum, but this could result from a change in the object's geometry within the band.

We then model Hen's 3-1191 spectral energy distribution (.4-60 ${\mu{\rm m}}$ ) and N-band visibilities. Because of the unknown nature of the object, we use a wide variety of models for objects with IR excesses. We find the observations to be consistent with a disc featuring an unusually high mass accretion and a large central gap almost void of matter, an excretion disc, and a binary made of two IR sources. We are unable to find a circumstellar shell model consistent with the data.

We review the different hypotheses concerning the physical nature of the star and conclude that it is neither a Be supergiant nor a symbiotic star. However, we could not discriminate between the scenario of a young stellar object featuring an unusually strong FU Orionis-like outburst of mass accretion ( $4{-}250\times10^~\ensuremath{M_\odot} /\ensuremath{{\rm yr}}$ ) and that of a protoplanetary nebula with an equatorial mass excretion rate $\ga$ $4 \times 10^\,\ensuremath{M_\odot} /\ensuremath{{\rm yr}}$ . In both cases, taking the additional presence of an envelope or wind into account would result in lower mass flows.

Key words: stars: emission-line, Be -- stars: individual: Hen 3-1191 -- planetary systems: protoplanetary disks -- infrared: stars -- accretion, accretion disks -- technique: interferometric

What is OpenURL?

Resolving the B[e] star Hen 3-1191 at 10 m with VLTI/MIDI

Resolving the B[e] star Hen 3-1191 at 10 $\mathsf{\mu}$ m with VLTI/MIDI