Imaging the dust sublimation front of a circumbinary disk

M. Hillen , J. Kluska , J. -B. Le Bouquin (1) , H. van Winckel , J. -P. Berger , D. Kamath , V. Bujarrabal

1 IPAG - Institut de Planétologie et d'Astrophysique de Grenoble

Aims: We present the first near-IR milli-arcsecond-scale image of a post-AGB binary that is surrounded by hot circumbinary dust.
Methods: A very rich interferometric data set in six spectral channels was acquired of IRAS 08544-4431 with the new RAPID camera on the PIONIER beam combiner at the Very Large Telescope Interferometer (VLTI). A broadband image in the H-band was reconstructed by combining the data of all spectral channels using the SPARCO method.
Results: We spatially separate all the building blocks of the IRAS 08544-4431 system in our milliarcsecond-resolution image. Our dissection reveals a dust sublimation front that is strikingly similar to that expected in early-stage protoplanetary disks, as well as an unexpected flux signal of ~4% from the secondary star. The energy output from this companion indicates the presence of a compact circum-companion accretion disk, which is likely the origin of the fast outflow detected in Hα.
Conclusions: Our image provides the most detailed view into the heart of a dusty circumstellar disk to date. Our results demonstrate that binary evolution processes and circumstellar disk evolution can be studied in detail in space and over time.

Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under program ID 094.D-0865.

Mots clés: stars: AGB and post-AGB; binaries: spectroscopic; techniques: high angular resolution; infrared: stars; techniques: interferometric; circumstellar matter

Domaines: Planète et Univers [physics]; Astrophysique [astro-ph]

M. Hillen, J. Kluska, J. -B. Le Bouquin, H. van Winckel, J. -P. Berger, et al.. Imaging the dust sublimation front of a circumbinary disk. Astronomy and Astrophysics - A&A, 2016, 588, ⟨10.1051/0004-6361/201628125⟩. ⟨insu-03634273⟩