Knots in the Outer Shells of the Planetary Nebulae IC 2553 and NGC 5882
Abstract
We present images and high-resolution spectra of the planetary nebulae IC 2553 and NGC 5882. Spatiokinematic modeling of the nebulae shows that they are composed of a markedly elongated inner shell and of a less aspherical outer shell expanding at a considerably higher velocity than the inner one. Embedded in the outer shells of both nebulae are found several low-ionization knots. In IC 2553, the knots show a point-symmetric distribution with respect to the central star: one possible explanation for their formation is that they are the survivors of preexisting point-symmetric condensations in the asymptotic giant branch wind, a fact that would imply a quite peculiar mass-loss geometry from the giant progenitor. In the case of NGC 5882, the lack of symmetry in the distribution of the observed low-ionization structures makes it possible that they are the result of in situ instabilities. Based on observations obtained at the 3.5 m New Technology Telescope (NTT) of the European Southern Observatory and with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA for NASA under contract NAS5-26555.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 2000
- DOI:
- 10.1086/317041
- arXiv:
- arXiv:astro-ph/0003238
- Bibcode:
- 2000ApJ...542..861C
- Keywords:
-
- ISM: Jets and Outflows;
- ISM: Kinematics and Dynamics;
- ISM: Planetary Nebulae: Individual: Alphanumeric: IC 2553;
- ISM: Planetary Nebulae: Individual: NGC Number: NGC 5882;
- Astrophysics
- E-Print:
- 20 pages including 1 table and 6 figures. ApJ accepted. Also available at http://andromeda.roque.ing.iac.es/~sanchez/ingpub/index2000.html