VLTI/AMBER unveils a possible dusty pinwheel nebula in WR118

F. Millour, T. Driebe, O. Chesneau, J. H. Groh, K. H. Hofmann, K. Murakawa, K. Ohnaka, D. Schertl, G. Weigelt

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)

Abstract

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-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.

Original languageEnglish
Pages (from-to)L49-L52
JournalAstronomy and Astrophysics
Volume506
Issue number3
DOIs
Publication statusPublished - 2 Nov 2009
Externally publishedYes

Keywords

  • Stars: circumstellar matter
  • Stars: individual: WR 118
  • Stars: winds, outflows
  • Stars: Wolf-Rayet
  • Techniques: interferometric
  • Techniques: spectroscopic

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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