A binary engine fuelling HD87643’s complex circumstellar environment, using AMBER/VLTI imaging

by F. Millour, O. Chesneau, M. Borges Fernandes, A. Meilland et al. 2009, A&A, 507, 317

The star HD 87643, exhibiting the “B[e] phenomenon”, has one of the most extreme infrared excesses for this object class. It harbours a large amount of both hot and cold dust, and is surrounded by an extended reflection nebula.

One of our major goals was to investigate the presence of a companion in HD87643. In addition, the presence of close dusty
material was tested through a combination of multi-wavelength high spatial resolution observations.

We observed HD 87643 with high spatial resolution techniques, using the near-IR AMBER/VLTI interferometer with
baselines ranging from 60 m to 130 m and the mid-IR MIDI/VLTI interferometer with baselines ranging from 25 m to 65 m. These observations are complemented by NACO/VLT adaptive-optics-corrected images in the K and L-bands, ESO-2.2m optical Wide-Field Imager large-scale images in the B, V and R-bands,

We report the direct detection of a companion to HD 87643 by means of image synthesis using the AMBER/VLTI instrument. The presence of the companion is confirmed by the MIDI and NACO
data, although with a lower confidence. The companion is separated by 34 mas with a roughly north-south orientation. The period must be large (several tens of years) and hence the orbital parameters are not determined yet. Binarity with high eccentricity might be the key to interpreting the extreme characteristics of this system, namely a dusty circumstellar envelope around the primary, a compact dust nebulosity around the binary system and a complex extended nebula witnessing past violent ejections.

The star HD 87643 is at the center of the extended nebula of dust and gas on the first image, obtained with the Wide Field Imager on the ESO MPG 2.2-metre telescope on La Silla. The central panel is a zoom on the star obtained with NACO on ESO's VLT on Paranal. The last panel zooms further , showing an image obtained with the AMBER instrument making use of three telescopes of the VLTI. The field of view of this last panel is less than one pixel of the first image.

See the ESO press release HERE