Computer Science
Scientific paper
Sep 1997
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1997phdt........11d&link_type=abstract
Thesis (PHD). UNIVERSITY OF VIRGINIA , Source DAI-B 58/03, p. 1329, Sep 1997, 189 pages.
Computer Science
2
Planetary Nebulae, Numerical Simulations
Scientific paper
This thesis, in three parts, explores salient aspects of the interaction of stars and supernova remnants (SNRs) with the surrounding medium. Part I investigates asphericity in planetary nebulae (PNe). PNe shapes are computed semi-analytically, assuming self-similar evolution in the framework of the interacting stellar winds model, with an equatorially enhanced density in the ambient wind. Hydrodynamic simulations substantiate our semi-analytical results, while providing some idea of their range of validity. The nebular morphology is shown to depend on the pole-to-equator density contrast, steepness of the density profile and velocity of the ambient medium. Part II considers Type Ia SNe, whose progenitors are thought to be white dwarfs which do not appreciably modify their environments. The interaction of the SN shock with a uniform ambient medium is investigated. An exponential ejecta density profile is used. Dimensionless results are presented for the evolution of the shock radii, velocities and expansion parameters. Profiles of the density, pressure and velocity in the interaction region are obtained, and their role in emission from the remnant considered. The results are applied to SN 1006 and SN 1572. An exponential ejecta density profile appears to work well for the former, but is not a good approximation for the latter. Part III addresses circumstellar interaction in high mass stars (M~> 8Msolar). Stellar mass-loss may result in the formation of circumstellar bubbles surrounding the star, bordered by a dense shell of swept up gas. When the star explodes as a SN, the shock wave interacts with the dense shell. The initial shock-shell interaction can be explored analytically (Chevalier & Liang 1989, ApJ, 344, 332), but the subsequent evolution must be studied numerically, as we do here. Our simulations differ from previous work in using a different density profile for the SN ejecta, and higher resolution. Analytical approximations are derived whenever possible. Shock-shell interaction is expected to occur in SN 1987A. We theorize that the presence of an HII region immediately interior to the bright equatorial ring can account for many of the puzzling properties inferred from radio and X-ray data on SN87A.
No associations
LandOfFree
Supernova and Stellar Wind Interaction with the Ambient Medium does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Supernova and Stellar Wind Interaction with the Ambient Medium, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Supernova and Stellar Wind Interaction with the Ambient Medium will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1294758