Wolf-Rayet stars probed by AMBER/VLTI
Millour, Florentin; Chesneau, Olivier; Driebe, Thomas; Petrov, Romain; Bonneau, Daniel; Dessart, Luc; Hofmann, Karl-Heinz; Weigelt, Gerd
Proceedings of the SPIE conference "Astronomical Instrumentation"
held in Marseille, France from June 23-28, 2008
SPIE Proceedings, Volume 7013, pg.70130T (1-9) (2008)
Abstract
Massive stars deeply influence their surroundings by their luminosity and the injection of kinetic energy. So far, they have mostly been studied with spatially unresolved
observations, although evidence of geometrical complexity of their wind are numerous. Interferometry can provide spatially resolved observations of massive stars and their
immediate vicinity. Specific geometries (disks, jets, latitude-dependent winds) can be probed by this technique. The first observation of a Wolf-Rayet (WR) star (\gamma^2 Vel)
with the AMBER/VLTI instrument yielded to a re-evaluation of its distance and an improved characterization of the stellar components, from a very limited data-set. This
motivated our team to increase the number of WR targets observed with AMBER. We present here new preliminary results that encompass several spectral types, ranging from
early WN to evolved dusty WC. We present unpublished data on WR79a, a massive star probably at the boundary between the O and Wolf- Rayet type, evidencing some Wolf-Rayet
broad emission lines from an optically thin wind. We also present new data obtained on \gamma^2 Vel that can be compared to the up-to-date interferometry-based orbital
parameters from North et al. (2007). We discuss the presence of a wind-wind collision zone in the system and provide preliminary analysis suggesting the presence of such
a structure in the data. Then, we present data obtained on 2 dusty Wolf-Rayet stars: WR48a-b and WR118, the latter exhibiting some clues of a pinwheel-like structure from
the visibility variations.
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