Optical line profiles of the Helix planetary nebula (NGC 7293) to large radii
Abstract
New, very long (25 arcmin), cuts of spatially resolved profiles of the Hα and [NII] optical emission lines have been obtained over the face of the Helix planetary nebula, NGC 7293. These directions were chosen to supplement previous similar, though shorter, cuts as well as crossing interesting phenomena in this nebular envelope. In particular, one new cut crosses the extremes of the proposed CO J = 2-1 emitting outer `torus' shown by Huggins and his coworkers to be nearly orthogonal to its inner counterpart. The second new cut crosses the extensive outer filamentary arcs on either side of the bright nebular core. It is shown that NGC 7293 is composed of multiple bipolar outflows along different axes. Hubble-type outflows over a dynamical time-scale of 11000 yr are shown to be occurring for all of the phenomena from the smallest HeII emitting core out to the largest outer filamentary structure. All must then have been ejected over a short time-scale but with a range of ejection velocities.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- February 2008
- DOI:
- 10.1111/j.1365-2966.2007.12710.x
- arXiv:
- arXiv:0711.3667
- Bibcode:
- 2008MNRAS.384..497M
- Keywords:
-
- planetary nebulae: individual: Helix nebula (NGC 7293);
- Astrophysics
- E-Print:
- 14 pages, 7 figures, MNRAS in press