Bulletin of the American Physical Society
2007 Annual Meeting of the Division of Nuclear Physics
Volume 52, Number 10
Wednesday–Saturday, October 10–13, 2007; Newport News, Virginia
Session CA: New Nucleosynthesis Processes |
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Chair: H. Schatz, Michigan State University Room: Newport News Marriott at City Center Grand Salon I |
Friday, October 12, 2007 9:00AM - 9:36AM |
CA.00001: Nucleosynthesis in the early Galaxy Invited Speaker: Recent observations of the abundances in metal-poor stars suggest that an additional mechanism besides the r-process is responsable for the production of material in the region Z$\le$47. Mixing of a light element primary process (LEPP) and the r-process pattern found in r-II metal-poor stars explain the apparent non-uniformity in their abundances. The LEPP abundance pattern based on those observations is used to explore the astrophysical conditions that would create it within a site-independant approach. In addition, a solar LEPP contribution is obtained by subtracting the contributions of other nucleosynthesis processes and it can be used to obtained information in the important A=130 abundance peak. The likely nature of the LEPP and its potential relevance for the s-process will be discussed. [Preview Abstract] |
Friday, October 12, 2007 9:36AM - 10:12AM |
CA.00002: Exposing the Nuclear Burning Ashes of Radius Expansion Type I X-Ray Bursts Invited Speaker: Type I X-ray bursts are powered by thermonuclear burning of freshly accreted H and He on the surface of a neutron star in a low-mass X-ray binary. The ashes of this burning are ordinarily hidden from view, buried well below the overlying photosphere. We show, however, that some of the ashes become exposed during especially bright X-ray bursts, known as photospheric radius expansion bursts. During such bursts, a radiation-driven wind forms, which our calculations show ejects as much as 1\% of the recently forged ashes of burning. The spectral signature of these ejected ashes should be detectable with current high-resolution X-ray telescopes. A detection would help constrain the nuclear burning processes and might enable a measurement of the gravitational redshift of the neutron star. [Preview Abstract] |
Friday, October 12, 2007 10:12AM - 10:48AM |
CA.00003: The Neutrino p-Process Invited Speaker: I will review the astrophysical conditions necessary for the $\nu p$-process, the relevant nuclear physics input, and its impact on our understanding of the origin of the elements. [Preview Abstract] |
Friday, October 12, 2007 10:48AM - 11:24AM |
CA.00004: New Regimes for Thermonuclear Supernovae Invited Speaker: Powering celestial events with radioactive decays of freshly minted elements has been understood for over 30 years now, with the Type Ia supernovae being the most observed event. I will start by reviewing the diversity of the presently known Type Ia supernovae population and its dependence on the type of host galaxy. However, most of my talk will present our (Bildsten, Shen, Weinberg and Nelemans 2007, ApJ, 662, L95) work on a new kind of thermonuclear supernovae from AM Canum Venaticorum binaries. Helium that accretes onto the C/O white dwarf in these binaries undergoes one large flash that is violent enough to create (and eject) 0.02-0.1 solar masses of radioactive 56Ni, 52Fe and 48Cr. This powers a faint and rapidly rising (few days) thermonuclear supernova every 5,000-15,000 years in a typical elliptical galaxy (about 2-6 \% of the Type Ia supernovae rate). These ``.Ia'' supernovae (one-tenth as bright for one-tenth the time as a Type Ia supernovae) are excellent targets for all upcoming celestial survey, yielding between 1 (Pan-STARRS-1) and 30 (LSST) .Ia supernovae per month. Finding and studying these events would allow for the first concrete link between a binary scenario and a thermonuclear supernova. [Preview Abstract] |
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