Bulletin of the American Physical Society
2007 Ohio Section APS/SOS/AAPT Joint Fall Meeting
Volume 52, Number 15
Friday–Saturday, October 19–20, 2007; Oxford, Ohio
Session D2: Astrophysics and Gravitation |
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Chair: Stephen Alexander, Miami University Room: Culler Hall 134 |
Saturday, October 20, 2007 9:06AM - 9:18AM |
D2.00001: Ten Minutes in the Dark James Beichler Both Dark Matter (DM) and Dark Energy (DE) can be explained using a single extended model of the space-time continuum. The Cold Dark Matter halo around spiral galaxies emerges as a natural consequence of the geometry after adding a macroscopic fourth dimension of space to normal four-dimensional space-time. Once DM is explained, the DE that is increasing the rate of expansion of the universe follows. No changes to General Relativity are required beyond the realization that curvature is an extrinsic property of the four-dimensional space-time continuum. Kaluza's five-dimensional unification of General Relativity and electromagnetic theory is completely explained by this model. [Preview Abstract] |
Saturday, October 20, 2007 9:18AM - 9:30AM |
D2.00002: The Formation and Evolution of Solar Systems Lori Beerman, Michael Sitko It is not known whether all solar systems form in a similar manner, or even from the same ingredients. By viewing other solar systems within our galaxy that are still in their infancy, we can better understand where we came from as well as the possibility that we may not be alone in the universe. We have chosen to observe a number of ``baby'' solar systems and analyze their mechanics and chemistry in order to make these correlations. After spectroscopic analysis, we have found that it is likely that the planet formation process has already begun in at least one of the the disks. Furthermore, the silicate and carbon-rich composition of this disk is comparable to the composition of our early solar system, which provides evidence that solar systems that are forming today are doing so in a similar manner to ours, and the precursors to life are common in the universe. [Preview Abstract] |
Saturday, October 20, 2007 9:30AM - 9:42AM |
D2.00003: Optical and Multiwavelength Variability Studies of Active Galaxies Markus Boettcher Highlights of recent results of observational and theoretical research on a class of active galaxies termed blazars, at Ohio University are presented. Specifically, we use the MDM observatory on Kitt Peak, AZ, to study the long- and short-term variability of blazars in the optical, and correlate such observations with simultaneous studies at radio, near-infrared, X-ray, and gamma-rays in intensive multiwavelength observing campaigns. I will focus on the role of undergraduate and graduate students in the observations, data collection and reduction, and theoretical interpretation. [Preview Abstract] |
Saturday, October 20, 2007 9:42AM - 9:54AM |
D2.00004: Survivability of Planetary Satellites During the Uranus/Neptune Ejection N.H. Selan, S.G. Alexander, N.P. Abel Recent work has proposed that the ice giant planets, Uranus and Neptune, did not form where they are located today in the Solar System. Instead, they originated in the present region of the gas giants, Jupiter and Saturn, and then were later gravitationally scattered into highly eccentric orbits that took them out into the Kuiper belt. Interactions with the Kuiper belt objects would slowly circularize their orbits to their present semi-major axes and eccentricities. It is unclear if the ejection process has any effect on systems of planetary satellites that may have existed at this time. We investigate this possibility through a series of simulations that include satellite systems around both the gas giants and the ice giants. For initial conditions, we chose to duplicate those of Tsiganis et al. (2005) where the ejection is caused by a Jupiter/Saturn resonance crossing. Preliminary results of several simulations are presented. [Preview Abstract] |
Saturday, October 20, 2007 9:54AM - 10:06AM |
D2.00005: N-Body Simulation and Visualization of Stellar Clusters Jeremy D. Hohertz, S.G. Alexander We have constructed a gravitational N-body simulation to study the evolution of stellar clusters. Our integration is based on the Hermite Individual Timestep Scheme (HITS) which accurately follows close interactions and collisions, and conserves energy to within acceptable limits. We discuss preliminary results of simulations that include a stellar mass distribution based on a three power law initial mass function. We also present a visualization technique that can be used as a tool in analyzing simulations and discuss plans for future studies. [Preview Abstract] |
Saturday, October 20, 2007 10:06AM - 10:18AM |
D2.00006: SH+ in the Diffuse ISM Nicholas Abel SH+ is a simple diatomic molecule which should be observed in many astrophysical environments by Hershel. Attempts of chemical models to form SH+ in the diffuse ISM are problematic, owing to the fact that S+ + H2 is highly endoergic. Recent work suggests SH+ can form as a result of x-ray induced chemistry in protoplanetary disks and in the molecular gas around an AGN. In this talk, I explore the effects of x-rays on the formation of SH+ in diffuse clouds, along with its trickle-down effects on our understanding of sulfur chemistry in these environments. [Preview Abstract] |
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