Volume 506, Number 3, November II 2009
|Page(s)||L49 - L52|
|Published online||24 September 2009|
Letter to the Editor
VLTI/AMBER unveils a possible dusty pinwheel nebula in WR118 *
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany e-mail: email@example.com
2 Observatoire de la Côte d'Azur/CNRS, UMR 6525 H. Fizeau, Univ. Nice Sophia Antipolis, Avenue Copernic, 06130 Grasse, France
Accepted: 23 September 2009
Context. Most Wolf-Rayet stars (WR) of the WC9 subtype exhibit a dusty circumstellar envelope, but it is still a matter of debate how dust can form in their harsh environment. In a few cases, a pinwheel-like structure of the dusty envelope has been detected; therefore, it has been suggested that dust formation in all dusty WR stars might be linked to colliding winds in a binary system.
Aims. We probed the innermost region of the circumstellar dust shell of the deeply embedded WR star WR 118.
Methods. We carried out spectro-interferometric observations using the AMBER instrument of ESO's Very Large Telescope Interferometer in low-spectral resolution mode (). The K-band observations were obtained with three 1.8 m telescopes spanning projected baselines between 9.2 and 40.1 m.
Results. At high spatial frequencies, the AMBER visibilities exhibit a prominent lobe, indicating that the envelope contains one or several zones with a large local intensity gradient. The strong closure phase signal clearly shows that the circumstellar envelope of WR 118 can only be described by an asymmetric intensity distribution. We show that a pinwheel nebula seen at low inclination is consistent with the AMBER data. Its size was determined to be mas.
Conclusions. WR 118 possibly harbors a pinwheel nebula, which suggests a binary nature of the system. According to our best model, the period of the system would be ≈60 days (for kpc), making WR 118 the shortest-period pinwheel nebula known so far.
Key words: stars: individual: WR 118 / stars: Wolf-Rayet / stars: winds, outflows / stars: circumstellar matter / techniques: interferometric / techniques: spectroscopic
© ESO, 2009
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.