The massive expanding molecular torus in the planetary nebula NGC 6302

Free access article

Issue		A&A Volume 473, Number 1, October I 2007


Page(s)		207 - 217
Section		Stellar structure and evolution
DOI		http://dx.doi.org/10.1051/0004-6361:20066973

A&A 473, 207-217 (2007)
DOI: 10.1051/0004-6361:20066973

The massive expanding molecular torus in the planetary nebula NGC 6302

N. Peretto¹, G. Fuller¹, A. Zijlstra¹, and N. Patel²

¹ School of Physics and Astronomy, University of Manchester, Sackville Street, PO Box 88, Manchester M60 1QD, UK
e-mail: nicolas.peretto@manchester.ac.uk
² Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS78, Cambridge, Massachusetts 02138, USA

(Received 19 December 2006 / Accepted 26 June 2007)

Abstract
Aims.We measure the mass and kinematics of the massive molecular torus in the the proto-typical butterfly planetary nebula NGC 6302. Determining the mass-loss history of the source is an important step in understanding the origin and formation of the wing-like morphology.
Methods. Using the SMA interferometer we have imaged both the continuum emission and the J=2-1 transitions of ¹²CO and ¹³CO at arcsecond resolution. These data are analysed in combination with observations of both the J=2-1 and J=3-2 transitions of ¹²CO and ¹³CO made with JCMT.
Results. The ¹²CO and ¹³CO emission match the dark lane seen in absorption in the H ${\alpha}$ image of the object and trace an expanding torus of material. The CO indicates a mass of the torus of ~2 $M_\odot \pm 1$ $M_\odot$ . The torus is expanding with a velocity of ~8 km s^-1, centred at $V_{\rm lsr}=-31.5\rm\,km\,s^{-1}$ . The size and expansion velocity of the torus indicates that it was ejected from ~7500 yr to 2900 yr ago, with a mass-loss rate of $5\times10^{-4}\,M_\odot\,\rm yr^{-1}$ . In addition we detect a ballistic component in the CO images which has a velocity gradient of 140 km s^-1 pc^-1.
Conclusions.The derived mass-loss history of the torus favours binary interaction as the cause of the ejection of the torus and we predict the existence of a companion with an orbital period $P\lesssim 1\,$ month.

Key words: stars: AGB and post-AGB -- planetary nebulae: general -- planetary nebulae: individual: NGC 6302

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.