EDP Sciences
Free access
Issue
A&A
Volume 493, Number 2, January II 2009
Page(s) L17 - L20
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:200811173
Published online 04 December 2008


A&A 493, L17-L20 (2009)
DOI: 10.1051/0004-6361:200811173

Letter

A dense disk of dust around the born-again Sakurai's object

O. Chesneau1, G. C. Clayton2, F. Lykou3, O. De Marco4, C. A. Hummel5, F. Kerber5, E. Lagadec3, J. Nordhaus6, A. A. Zijlstra3, and A. Evans7

1  UMR 6525 H. Fizeau, Univ. Nice Sophia Antipolis, CNRS, Observatoire de la Côte d'Azur, Av. Copernic, 06130 Grasse, France
    e-mail: olivier.chesneau@ob-azur.fr
2  Department of Physics & Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA
3  Jodrell Bank Centre for Astrophysics, The A. Turing Building, The Univ. of Manchester, Oxford Rd, Manchester M13 9PL, UK
4  Department of Astrophysics, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, USA
5  European Southern Observatory, Karl-Schwarzschild-Strasse 2 85748 Garching bei München, Germany
6  Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA
7  Astrophysics Group, Lennard-Jones Laboratories, Keele University, Staffordshire ST5 5BG, UK

Received 17 October 2008 / Accepted 18 November 2008

Abstract
Context. In 1996, Sakurai's object (V4334 Sgr) suddenly brightened in the center of a faint Planetary Nebula (PN). This very rare event was interpreted as being the reignition of a hot white dwarf that caused a rapid evolution back to the cool giant phase. From 1998 on, a copious amount of dust has formed continuously, screening out the star that remained embedded in this expanding high optical-depth envelope.
Aims. We present observations that we use to study the morphology of the circumstellar dust to investigate the hypothesis that Sakurai's Object is surrounded by a thick spherical envelope of dust.
Methods. We acquired unprecedented, high angular-resolution, spectro-interferometric observations, with the mid-IR interferometer MIDI/VLTI, which resolved the dust envelope of Sakurai's object.
Results. We report the discovery of a unexpectedly compact ( $30 \times 40$ milliarcsec, $105 \times 140$ AU assuming a distance of 3.5 kpc), highly inclined, dust disk. We used Monte Carlo radiative-transfer simulations of a stratified disk to constrain its geometric and physical parameters, although such a model is only a rough approximation of the rapidly evolving dust structure. Even though the fits are not fully satisfactory, some useful and robust constraints can be inferred. The disk inclination is estimated to be 75° $\pm$ 3° with a large scale height of 47 $\pm$ 7 AU. The dust mass of the disk is estimated to be $6 \times 10^{-5}~M_{\odot}$. The major axis of the disk (132° $\pm$ 3°) is aligned with an asymmetry seen in the old PN which was re-investigated as part of this study. This implies that the mechanism responsible for shaping the dust envelope surrounding Sakurai's object was already at work when the old PN formed.


Key words: ISM: planetary nebulae: individual: Sakurai's object -- stars: AGB and post-AGB -- stars: circumstellar matter -- stars: mass-loss -- techniques: high angular resolution -- techniques: interferometric



© ESO 2009

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access.

An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account.
    In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.