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Heger_A

Research Abstracts Online
January 2009 - March 2010

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University of Minnesota Twin Cities
Institute of Technology
School of Physics and Astronomy
Department of Physics

PI: Alexander Heger

Stellar Explosions and the Origin of the Elements

This research comprises three individual projects.

The first involves two- and three-dimensional simulations of pair-instability supernova explosions, probably the most powerful thermonuclear explosions in the universe. Such explosions come from some of the most massive stars in the universe, stars that are at least 150 times as massive as our sun. Such massive stars may have been common among the first generation of stars to ever form, however, recent astronomical observations suggest that such explosions still occur today. These simulations are among the first of this kind. This study intends to determine the energy generated, the mixing processes, and genesis of heavy elements made in these supernovae.

The second project is simulations of Type I x-ray bursts. Specifically the researchers intend to produce an extended grid of models as a function of neutron star accretion rate, accretion compositions, and neutron star properties such as radius, mass, and luminosity. This will yield for the first time an extended model library that can be used by observational astronomers to compare with their data and help to place constrained neutron star properties such as mass radius, and as a consequence, on the neutron star equation of state. Conversely, the results from these grids will allow researchers to improve the models themselves from determining which are excluded by observations.

The final project involves an extended grid of stellar evolution models including complete nucleosynthesis. Hundreds of stars will be simulated, plus some 10 supernovae for each star. This will be done for different initial stellar metallicities and different initial stellar rotation rates to reproduce the galactochemical evolution of the universe.

Group Members

Ke-Jung (Ken) Chen, Graduate Student
Laurens Keek, Research Associate