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

Florentin Millour (1) , Olivier Chesneau (2) , Marcelo Borges Fernandes (2) , Anthony Meilland (1) , Gilbert Mars (3) , C. Benoist (4) , Éric Thiébaut (5) , Philippe Stee (2) , K.-H. Hofmann (1) , Fabien Baron (6) , John R. Young (6) , Philippe Bendjoya (2) , A. C. Carciofi (7) , Armando Domiciano de Souza (2) , Thomas Driebe (1) , Slobodan Jankov (2) , Pierre Kervella (8) , R. G. Petrov (2) , Sylvie Robbe-Dubois (2) , Farrokh Vakili (2) , L. B. F. M. Waters (9) , Gerd Weigelt (1)

1 MPIFR - Max-Planck-Institut für Radioastronomie
2 FIZEAU - Laboratoire Hippolyte Fizeau
3 FRESNEL - Département Fresnel
4 CASSIOPEE - Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides
5 CRAL - Centre de Recherche Astrophysique de Lyon
6 Cavendish Laboratory
7 IAG - Instituto de Astronomia, Geofísica e Ciências Atmosféricas [São Paulo]
8 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique
9 AI PANNEKOEK - Astronomical Institute Anton Pannekoek

Context. 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. Aims. 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. Methods. 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, Results. 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.

Domaines: Astrophysique stellaire et solaire [astro-ph.SR]; Astrophysique stellaire et solaire [astro-ph.SR]

Florentin Millour, Olivier Chesneau, Marcelo Borges Fernandes, Anthony Meilland, Gilbert Mars, et al.. A binary engine fuelling HD87643' s complex circumstellar environment, using AMBER/VLTI. Astronomy and Astrophysics - A&A, 2009. ⟨hal-00408751v2⟩