Bulletin of the American Physical Society
76th Annual Meeting of the Southeastern Section of APS
Volume 54, Number 16
Wednesday–Saturday, November 11–14, 2009; Atlanta, Georgia
Session CA: Nuclear Physics in the Cosmos |
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Chair: Jorge Piekarewicz, Florida State University Room: Amsterdam |
Thursday, November 12, 2009 10:45AM - 11:15AM |
CA.00001: Massive Stars: Input Nuclear Physics and Stellar Models Invited Speaker: Stars with masses greater than about twelve times the mass of our Sun play a crucial role in astrophysics, especially in the evolution of galaxies and the growth of the abundances of the chemical elements. I present a general overview of the structure and evolution of such stars, particularly during their pre-supernova stages. I discuss some of the many physical uncertainties still encountered in modeling massive star evolution. These uncertainties include the effects of mass loss, convection, rotation, and initial metallicity. I pay particular attention to the role of some key nuclear reactions and the effects of uncertainties in the rates for these reactions. Finally, I discuss some details of the massive-star nucleosynthesis of the s-process and of two key nuclei observable by gamma-ray telescopes, namely, aluminum-26 and iron-60. [Preview Abstract] |
Thursday, November 12, 2009 11:15AM - 11:45AM |
CA.00002: Neutrinos and nucleosynthesis from Supernovae and Gamma Ray Bursts Invited Speaker: We discuss the way in which neutrinos together with ambient conditions impact the nucleosynthesis in extreme astrophysical environments such as supernovae and gamma ray bursts. Hot dense material near the center of these objects will be composed of free nucleons. As this material flows outward, it cools and combines into nuclei and creates some of the elements we find on earth today. Neutrinos are an important aspect of this process for many reasons, one of which is that since they are emitted in great numbers, through the charged current interactions, they determine the relative numbers of neutrons and protons in the material. We examine several effects of neutrinos on the nucleosynthesis in both environments. [Preview Abstract] |
Thursday, November 12, 2009 11:45AM - 12:15PM |
CA.00003: TBD Invited Speaker: |
Thursday, November 12, 2009 12:15PM - 12:45PM |
CA.00004: Challenges and recent results on the structure of r-process nuclei Invited Speaker: The astrophysical rapid neutron-capture process (r-process) has been recognized for a long time as the scenario responsible for the synthesis of approximately half of the nuclear species in nature, which are more massive than Fe. It requires environments with a high neutron density, where neutron captures are faster than beta decays even for neutron-rich unstable nuclei up to 15 to 30 units from stability. Unfortunately, almost nothing is known about the structure of the majority of the extremely neutron-rich nuclei involved in the reaction flow. The evolution of shell structure away from stability can have dramatics effects on the produced r-process abundances. Furthermore during freezeout, individual reactions near neutron closed-shell nuclei can also significantly affect the final abudances. Now with the development of exotic beam facilities such as the Holifield Radioactive Ion Beam Facility (HRIBF), measurements with accelerated beams of fission fragments are providing some of the first spectroscopic information on many r-process nuclei. I will review the measurements made at the HRIBF as well as describe future opportunities to greatly advance these studies. [Preview Abstract] |
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