* Astronomy

Blobrana · L

HD 87643

Blobrana · L

RE: HD87643

Blobrana · L

Double Engine for a Nebula
ESO has just released a stunning new image of a field of stars towards the constellation of Carina (the Keel). This striking view is ablaze with a flurry of stars of all colours and brightnesses, some of which are seen against a backdrop of clouds of dust and gas. One unusual star in the middle, HD 87643, has been extensively studied with several ESO telescopes, including the Very Large Telescope Interferometer (VLTI). Surrounded by a complex, extended nebula that is the result of previous violent ejections, the star has been shown to have a companion. Interactions in this double system, surrounded by a dusty disc, may be the engine fuelling the stars remarkable nebula.
The new image, showing a very rich field of stars towards the Carina arm of the Milky Way, is centred on the star HD 87643, a member of the exotic class of B[e] stars. It is part of a set of observations that provide astronomers with the best ever picture of a B[e] star.

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Blobrana · L

Title: A binary engine fuelling HD87643' s complex circumstellar environment, using AMBER/VLTI
Authors: Florentin Millour (MPIFR), Olivier Chesneau (FIZEAU), Marcelo Borges Fernandes (FIZEAU), Anthony Meilland (MPIFR), Gilbert Mars (FRESNEL), C. Benoist (CASSIOPEE), E. Thiébaut (CRAL), Philippe Stee (FIZEAU), K.-H. Hofmann (MPIFR), Fabien Baron, John R. Young, Philippe Bendjoya (FIZEAU), A. C. Carciofi, Armando Domiciano De Souza (FIZEAU), Thomas Driebe (MPIFR), Slobodan Jankov (FIZEAU), Pierre Kervella (LESIA), R. G. Petrov (FIZEAU), Sylvie Robbe-Dubois (FIZEAU), Farrokh Vakili (FIZEAU), L. B. F. M. Waters (AI PANNEKOEK), Gerd Weigelt (MPIFR)

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 refection 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.

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