Bulletin of the American Physical Society
Joint Spring 2010 Meeting of the Texas Sections of the APS, AAPT, and SPS
Volume 55, Number 3
Thursday–Saturday, March 18–20, 2010; Austin, Texas
Session J3: Astrophysics, Space Physics, Astronomy, Cosmology |
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Chair: James Friedrichsen, Austin Community College Room: Robert Lee Moore Hall 5.112 |
Saturday, March 20, 2010 10:15AM - 10:27AM |
J3.00001: Quantifying Chaos in the Three Body Problem Billy Quarles, Zdzislaw Musielak The Circular Restricted 3-Body Problem (CR3BP) has been studied for many years. Classically it has been shown to potentially lead to chaos. However, instability and chaos are not synonymous. In exploring numerically the orbits in the CR3BP, we seek to establish criteria by determining which initial conditions will produce stable or chaotic orbits. By using the method of Lyapunov exponents we can quantify which orbits are chaotic. This project looks to explore this area by using student developed Java programs to perform the numerical integrations of the orbits as well as Lyapunov exponent determination. Additionally, we have developed software to visually show the orbit of the 3rd smaller from different reference points. By finding long term stable orbits in the CR3BP, we may be able to predict more exotic extra-solar planetary orbital configurations than what has already been observationally established. [Preview Abstract] |
Saturday, March 20, 2010 10:27AM - 10:39AM |
J3.00002: Radiation from Accelerating Electric Charges: The Third Derivative of Position Edward Butterworth While some textbooks appear to suggest that acceleration of an electric charge is both a necessary and sufficient cause for the generation of electromagnetic radiation, the question has in fact had an intricate and involved history. In particular, the acceleration of a charge in hyperbolic motion, the behavior of a charge supported against a gravitational force (and its implications for the Equivalence Principle), and a charge accelerated by a workless constraint have been the subject of repeated investigation. The present paper examines specifically the manner in which the third derivative of position enters into the equations of motion, and the implications this has for the emission of radiation. Plass opens his review article with the statement that ``A fundamental property of all charged particles is that electromagnetic energy is radiated whenever they are accelerated'' (Plass 1961; emphasis mine). His treatment of the equations of motion, however, emphasizes the importance of the occurrence of the third derivative of position therein, present in linear motion only when the rate of acceleration is increasing or decreasing. There appears to be general agreement that the presence of a nonzero third derivative indicates that this charge is radiating; but does its absence preclude radiation? This question leads back to the issues of charges accelerated by a uniform gravitational field. We will examine the equations of motion as presented in Fulton {\&} Rohrlich (1960), Plass (1961), Barut (1964), Teitelboim (1970) and Mo {\&} Papas (1971) in the light of more recent literature in an attempt to clarify this question. [Preview Abstract] |
Saturday, March 20, 2010 10:39AM - 10:51AM |
J3.00003: Treating Boundary Terms in the Hamiltonian Formulation of Gauge Theories Jerry Schirmer, Richard Matzner In this paper, the behavior of boundary terms in the Hamiltonians derived from gauge theories is investigated. While the typical treatment of these boundary terms is to omit them, declaring that the rules for the variation leaves these variables fixed on the boundary, a few simple examples shows that this is, in fact, an unsatisfactory approach for even simple examples in gauge theory. Using examples derived from Maxwell theory and from General Relativity, we show that it is in fact necessary to modify the original Hamiltonian by adding terms that normalize the values of these boundary terms. [Preview Abstract] |
Saturday, March 20, 2010 10:51AM - 11:03AM |
J3.00004: Measurements of Extrasolar Planetary Transits Kyle Meziere, Nicolas Wiseman, Jared Rovny, Elise Dinehart, Blaise Dufrain, Andrew Bechter, Eric Bechter, Richard Olenick, Arthur Sweeney A campaign to measure properties of extrasolar planets using the transit method was undertaken at the University of Dallas using a C-14 telescope and SBIG 2000XM CCD camera. We successfully recorded transits of TrES-1b, Wasp-3, and HatP1. The C-14 exposure and tracking data (on WASP-3) indicate that we can probably effectively monitor stars to 13.5 or 14 magnitude with the C-14. We present the transit data, modeling, and determined planetary characteristics. The equipment used in this research was comparatively inexpensive and widely available and can be implemented at other small universities. [Preview Abstract] |
Saturday, March 20, 2010 11:03AM - 11:15AM |
J3.00005: Rediscovering Kepler's laws using Newton's gravitation law and NASA data Paul Springsteen, Jason Keith Kepler's three laws of planetary motion were originally discovered by using data acquired from Tycho Brache's naked eye observations of the planets. We show how Kepler's third law can be reproduced using planetary data from NASA. We will also be using Newton's Gravitational law to explain why Kepler's three laws exist as they do. [Preview Abstract] |
Saturday, March 20, 2010 11:15AM - 11:27AM |
J3.00006: Simulation Studies of Muon Induced Neutron Background for a Homestake Dark Matter Experiment Riznia Jasim, Anton Empl, Ed Hungerford Fast neutrons from cosmic-ray muons, are an important background for dark matter experiments. Hence, to predict the sensitivity of a Homestake dark matter experiment, the background from neutrons must be precisely characterized. A detailed analysis of muon induced neutron background at the Homestake Mine is performed using the most recent version of the particle transport code, FLUKA. The results of the muon induced neutron flux, energy distribution, angular distribution and multiplicity at 4850 level in Homestake Mine is reported. The profile of the neutrons at the rock/laboratory boundary obtained from the simulation can be used as an input to study neutron shielding and to design a veto system for a Homestake dark matter experiment. [Preview Abstract] |
Saturday, March 20, 2010 11:27AM - 11:39AM |
J3.00007: The nuclear symmetry energy dependence of the nuclear `pasta' phases in the inner crust of neutron stars Michael Gearheart Neutron stars are the end point of the evolution of a star with between about 8 and 25 solar masses. The star's core collapses to form an object with about 1.5 times the mass of our Sun and a radius of only 10km. The average density of matter in a neutron star is comparable with that of the nuclei of atoms, making them interesting probes of nuclear physics in a regime inaccessible to terrestrial experiments. We present a study of the inner crust of neutron stars, a region of the star between 0.5km and 1km in depth where super-heavy neutron rich nuclei arranged in a lattice co-exist with a gas of neutrons. Near the transition from the inner crust to the core of the star, the nuclei are expected to assume exotic shapes such as cylinders and slabs, referred to collectively as nuclear `pasta'. Using a compressible liquid drop model and a variety of different descriptions of the nucleon-nucleon interaction, we examine the composition and shape of nuclei at different depths in the inner crust up to the point where the nuclei dissolve into a uniform fluid of neutrons, protons and electrons. We examine the dependence of the densities at which nuclear shape transitions occur on experimentally measurable properties of nuclear matter such as the nuclear symmetry energy. [Preview Abstract] |
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