Bulletin of the American Physical Society
2008 Joint Fall Meeting of the Texas and Four Corners Sections of APS, AAPT, and Zones 13 and 16 of SPS, and the Societies of Hispanic & Black Physicists
Volume 53, Number 11
Friday–Saturday, October 17–18, 2008; El Paso, Texas
Session H4: Astrophysics and Astronomy I |
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Chair: Verne Smith, National Optical Astronomy Observatory Room: Union East, 3rd Floor Smiley |
Saturday, October 18, 2008 10:30AM - 10:42AM |
H4.00001: Big and Bright: Two Discoveries from the Texas Supernova Search Robert Quimby Supernovae, the cosmic fireworks accompanying the catastrophic ends of some stars, have been the highly scrutinized subjects of multiple research consortia for decades. It is therefore initially surprising to learn that the most luminous and, in some sense, most obvious supernovae have only recently been found--and they were done so by one of the smallest telescopes competing in the field. In this talk I will review the Texas Supernova Search and our two most famous discoveries: SNe 2006gy and 2005ap. I will present the remarkable observations and a few of the theoretical models formulated to offer explanation. SN 2006gy is most likely an explosion from an exceptionally massive star and it is the first observed supernova for which a pair instability trigger must be considered. 2005ap, the most luminous supernova yet identified, may be a distinctly different phenomena, one perhaps related to gamma-ray bursts. I discuss possible reasons as to why such supernovae have yet to be found by other surveys. [Preview Abstract] |
Saturday, October 18, 2008 10:42AM - 10:54AM |
H4.00002: Orbits of selected stars in a barred Galactic potential Hector Noriega-Mendoza, Christine Allen, Edmundo Moreno Stellar orbits were numerically integrated in the barred Galactic potential of Pichardo, Martos and Moreno (2004). The stellar sample was taken from the catalog of low-metallicity stars of Beers et al. (2000) with known kinematic information. We present a preliminary comparison of orbital parameters in both axisymmetric and barred potentials, emphasizing the dispersive effects introduced by the central Galactic bar. [Preview Abstract] |
Saturday, October 18, 2008 10:54AM - 11:06AM |
H4.00003: Observations of Mrk 421 with VERITAS Kerianna Butler Markarian 421, a BL Lacertae object, is a variable source and can flare to many times that of the Crab Nebula. This source is observed by VERITAS, the Very Energetic Radiation Imaging Telescope Array System, which consists of four imaging atmospheric Cherenkov telescopes and is located in southern Arizona. During the 2007/2008 observing season we observed the source for over 30 hours and report the statistical significance to be 235 standard deviations. We compare our results to other years of data and summarize the mechanisms which are thought to cause the gamma ray emission. [Preview Abstract] |
Saturday, October 18, 2008 11:06AM - 11:18AM |
H4.00004: VERITAS observation of the Intermediate BL-Lac W Comae Michael Newbold The VERITAS imaging air-Cherenkov gamma-ray telescopes, located in southern Arizona at the Fred Lawrence Whipple Observatory observed the intermediate Bl Lacertae object W Comae (z= 0.102) from late 2007 to June of 2008 for 43 hours of data. In the course of this observation a flare was recorded in the TeV spectrum in March 2008. In my talk I will discuss this observation of W Comae and the analysis of the data using the standard GrISU analysis package, I will also briefly discuss the significance of the discovery of this new TeV source. [Preview Abstract] |
Saturday, October 18, 2008 11:18AM - 11:30AM |
H4.00005: ABSTRACT WITHDRAWN |
Saturday, October 18, 2008 11:30AM - 11:42AM |
H4.00006: Magnetic Fields in Quasar Jets and their Environments Christopher Walker, David Hough We observed radio jets in the cores of 15 lobe-dominated quasars at parsec-scale resolution using the NRAO VLBA. Measurements of fractional polarization (m) and rotation measure (RM) were used to explore four models of the magnetic field (B) in the jets and the surrounding medium. (1) We used the model of Wardle et al. (1994, ApJ, 437, 122), with shocks in a parallel-B flow to explain m variations along the jet, to find a shock-frame flow speed of $\sim$0.6c and a ratio of ordered to random B of $\sim$1 in the quasar 3C245. (2) A cylindrical jet model, with a parallel-B sheath of fractional thickness $\sim$0.1, reproduces observed m edge enhancements. (3) We used the model of Taylor (2000, ApJ, 533, 95), with a ``Faraday screen'' around the inner jet, for two trial B configurations: simple dipole and turbulent cells. Both can explain the observed rapid RM declines along the jets. (4) A conical jet model, with helical B causing internal Faraday rotation, reproduces observed m edge enhancements, but predicts an unobserved central peak in m. Finally, a comparative analysis of core-dominated quasars (Lister \& Homan, 2005, AJ, 130, 1389) suggests that parallel-B structures occur in all quasar jets. [Preview Abstract] |
Saturday, October 18, 2008 11:42AM - 11:54AM |
H4.00007: Computational Astrophysics Software for the Study of Near by Planetary Systems Ryan Haynes, John Armstrong In an effort to bring computational Astrophysics to the undergraduate level, a simplified analysis tool for simulating gravitational interaction of planets orbiting stars is needed. Many tools to integrate planetary systems and study their behavior have been developed. This project focuses on combining a well-developed N-body planetary integrator (Mercury) with a web application (Rails) to automate the simulation process, making studies of Extra Solar Planetary systems much easier. Ultimately this application will have the ability to simulate any system including objects such as test particles and planets, and then store this data for later scientific inquiry. One instance of this software has already been implemented on Weber State Universities computing cluster (Workhouse). Much work is still needed to perfect and distribute this software. [Preview Abstract] |
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