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

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 microns to 36 mas at 13 microns. The MIDI spectrum and visibilities show a curvature which can arise from a weak silicate feature in which the object appears ~ 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 microns) and N-band visibilities. Because of the unknown nature for 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. At last, 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 to 250 x 10^-4 solar mass per year) and that of a protoplanetary nebula with an equatorial mass excretion rate (>~ 4 x 10^-5 solar mass per year). In both cases, taking the additional presence of an envelope or wind into account would result in lower mass flows.

arXiv comment9 pages, 8 figures, 4 tables, 1 SIMBAD object Accepted by Astronomy & Astrophysics (manuscript AA-2006-6026)

References in corpus (13)

• Spectral Energy Distributions of T Tauri Stars With Passive Circumstellar Disks
• Passive irradiated circumstellar disks with an inner hole
• A 10 micron spectroscopic survey of Herbig Ae star disks: grain growth and crystallization
• C2D Spitzer-IRS spectra of disks around T Tauri stars: I. Silicate emission and grain growth
• Spatially Resolved Circumstellar Structure of Herbig Ae/Be Stars in the Near-Infrared
• The near-infrared size-luminosity relations for Herbig Ae/Be disks
• Viscous Transonic Decretion in Disks of Be Stars
• X-ray Study of the Intermediate-Mass Young Stars Herbig Ae/Be Stars
• New insights on the AU-scale circumstellar structure of FU Orionis
• FU Orionis resolved by infrared long baseline interferometry at a 2-AU scale
• Kinematical structure of the circumstellar environments of galactic B[e]-type stars
• On the optical--infra-red continuum emission from equatorial discs of supergiant B[e] stars
• The vertical structure of T Tauri accretion discs III. Consistent interpretation of spectra and visibilities with a two-layer model

Cited by in corpus (6)

• Polycyclic Aromatic Hydrocarbon in Protoplanetary Disks around Herbig Ae/Be and T Tauri Stars
• Broadband ESO/VISIR-Spitzer infrared spectroscopy of the obscured supergiant X-ray Binary IGR J16318-4848
• Near Infrared polarimetry of a sample of YSOs
• Optical and infrared study of the obscured B[e] supergiant high-mass X-ray binary IGR J16318-4848
• Herschel observations of dust around the high-mass X-ray binary GX 301-2
• Interferometric science results on young stellar objects