Dynamical evolution of planetary nebulae. I - Formation of shells in an accelerating wind in protoplanetary nebulae
Abstract
Evolutionary calculations of central stars of planetary nebulae show a time-dependent increase in surface temperature. The high-speed winds, which these stars emit, expand into a previously ejected 'superwind' and are most likely driven by radiation pressure. Hence a model explaining the dynamical evolution of the surrounding planetary nebulae must take into account that the wind speed increases and the mass-loss rate decreases with time. It is shown that at an early stage a shell will form and that the flow changes from momentum to energy driven, once the wind speed is in excess of 150 km/s. Radii and velocities of these shells are generally lower in an accelerating wind model than in the simple multiple-winds model. Another important difference is the occurrence of Rayleigh-Taylor instabilities in the shell when the flow is energy driven.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- February 1990
- DOI:
- 10.1093/mnras/242.3.505
- Bibcode:
- 1990MNRAS.242..505K
- Keywords:
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- Computational Astrophysics;
- Planetary Nebulae;
- Stellar Envelopes;
- Stellar Evolution;
- Stellar Winds;
- Abundance;
- Astronomical Models;
- Helium;
- Protoplanets;
- Taylor Instability;
- Astrophysics