Bulletin of the American Physical Society
2006 Texas Section of the APS Joint Fall Meeting
Thursday–Saturday, October 5–7, 2006; Arlington, Texas
Session AP1: Astrophysics I |
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Chair: Carlos Ordonez, University of Houston Room: UT Arlington, University Center Red River |
Friday, October 6, 2006 10:30AM - 10:42AM |
AP1.00001: Anomalously Blue Ellipticals in the Sloan Survey Michael Fanelli, Pamela Marcum, Chris Fuse Recently, we identified two isolated early-type galaxies with unusually blue optical colors (Marcum etal, AJ 127, 3213), indicating current or recent massive star formation. Merger-induced star formation is the most likely mechanism for the odd photometric properties of these systems, yet, interestingly, they do not show the strong morphological scars (tidal tails, shells) generally attributed to merger activity. We concluded that these systems are late stage mergers, in which those morphological scars have largely dissipated, but photometric anomalies remain. To further explore the evolutionary paths of elliptical galaxies, we are ``mining'' the Sloan Digital Sky Survey for anomalously blue ellipticals, which may represent local universe analogues to distant young galaxies. We will describe representative objects and outline their properties. [Preview Abstract] |
Friday, October 6, 2006 10:42AM - 10:54AM |
AP1.00002: Substructure in the Galactic Halo Kenneth Carrell, Ron Wilhelm New and exciting evidence for stellar substructure is being discovered in our Galactic halo. This presentation will highlight the development of a more rigorous and quantitative way to characterize some of these structures. The use of kinematic, spatial and chemical abundance data for a large sample of stars along with a novel clustering technique will be used to achieve this goal. [Preview Abstract] |
Friday, October 6, 2006 10:54AM - 11:06AM |
AP1.00003: DyFK-simulation-based formulaic representation of the effects of wave-driven ion heating and electron precipitation on ionospheric outflows James Horwitz, Wen Zeng There is great interest in the magnetospheric community in obtaining compact representations of the ionospheric outflow fluxes and their relationships to putative drivers. Recently, analyses of measurements by FAST and POLAR have led to best fit formulas for the measurement-based relationships of the outflows levels to parameterizations for electron precipitation and Poynting fluxes, which are expected to be among the principal drivers, or closely related to them, for the ionospheric outflows. In this presentation, we shall use the results of an extensive set of systematic simulation runs with our Dynamic Fluid Kinetic (DyFK) simulation code for ionospheric plasma field-aligned transport to obtain O$^{+}$ outflow flux levels versus precipitation electron energy flux levels and the peak spectral wave densities for BBELF waves which transversely heat ionospheric ions. We shall present spectrograms of the relationship of the ion outflow values to these electron energy flux and BBELF wave levels. A preliminary approximate formulaic representation at this time is: Flux$_{O+}$ = 5(3.0x10$^{9}$ + 0.02x10$^{13 }$f$_{e }^{1.4}$ tanh(8D$_{wave})$+0.2D$_{wave}^{0.6}$ ) where Flux$_{O+}$ is the O$^{+}$ number flux in m$^{-2}$s$^{-1}$ at 3R$_{E}$ mapped to 1000 km altitude, f$_{e}$ is the electron precipitation energy flux in ergs cm$^{-2}$s$^{-1}$, and D$_{wave}$ is the wave spectrum density at 6.5 Hz in mV$^{2}$m$^{-2}$ Hz$^{-1}$. This work was completed under financial support by NASA grant NNG05GF67G and NSF grant ATM-0505918 to the University of Texas at Arlington. [Preview Abstract] |
Friday, October 6, 2006 11:06AM - 11:18AM |
AP1.00004: Astrobiological Effects of Stellar Radiation in Circumstellar Environments Manfred Cuntz, Levent Gurdemir, Edward F. Guinan, Robert L. Kurucz The centerpiece of all life on Earth is carbon-based biochemistry. Previous scientific research has suggested that biochemistry based on carbon may also play a decisive role in extraterrestrial life forms, i.e., alien life outside of Earth, if existent. In the following, we explore if carbon-based macromolecules (such as DNA) in the environments of stars other than the Sun are able to survive the effects of energetic stellar radiation, such as UV-C in the wavelength band between 200 and 290 nm. We focus on main-sequence stars akin to the Sun, but of hotter (F-type stars) and cooler (K- and M-type stars) surface temperature. Emphasis is placed on investigating the radiative environment in stellar habitable zones (HZs). Stellar habitable zones have an important relevance in astrobiology because they constitute circumstellar regions in which a planet of suitable size can have surface temperatures for water to exist in liquid form. [Preview Abstract] |
Friday, October 6, 2006 11:18AM - 11:30AM |
AP1.00005: Expansion Rates of Planetary Nebulae and Supernova Remnants Aimee Solis, Kristen Allen, Ashley Marshall This presentation describes a research project in which archive photos and current images of specific nebulae were compared. The relative size of each nebula in relation to its background stars was examined for images taken over a fifty year time span. This data was used to determine the rates on expansion for the nebulae in question. [Preview Abstract] |
Friday, October 6, 2006 11:30AM - 11:42AM |
AP1.00006: Cutoff-Free Propagation of Torsional Waves Along Solar Magnetic Flux Tubes Swati Routh, Zdzislaw Musielak, Reiner Hammer Solar magnetic flux tubes support three fundamental modes, namely, longitudinal, transverse and torsional tube waves. Previous studies showed that cutoff frequencies exist for both longitudinal and transverse tube waves, however, for torsional tube waves contradictory results regarding the existence of a cutoff frequency were obtained. The main purpose of this paper is to show that the propagation of torsional waves along thin magnetic flux tubes embedded in the solar atmosphere is not affected by any cutoff frequency and that this result is independent of coordinate systems used in the previous studies. Implications of this cutoff-free torsional tube wave propagation on the heating of different parts of the solar atmosphere will also be discussed. [Preview Abstract] |
Friday, October 6, 2006 11:42AM - 11:54AM |
AP1.00007: Fractal Geometry in One Dimensional Models of the Expanding Universe Bruce Miller, Jean-Louis Rouet Concentrations of matter in the universe, such as galaxies and galactic clusters, originated as very mall density fluctuations in the early universe. The fluctuation spectrum is revealed by studies of the angular correlation of CBM across the sky with WMAP. The existence of galaxy clusters and super-clusters suggests that a natural scale for the matter distribution may not exist. A point of controversy is whether the distribution is fractal and, if so, over what range of scales. The assumed source of fractal behavior is the lack of a length scale in the two body gravitational interaction. However, even with new, larger, sample sizes from recent surveys, it is difficult to extract information concerning fractal properties with confidence. Similarly, simulations with a billion particles only provide a thousand particles per dimension, far too small for accurate conclusions. With one dimensional ``toy models'' we can overcome these limitations by carrying out simulations with on the order of a quarter of a million particles. Here we present the recent results of our ongoing investigation of the fractal geometry of one dimensional models of the expanding universe. [Preview Abstract] |
Friday, October 6, 2006 11:54AM - 12:06PM |
AP1.00008: Extremely Isolated Early-Type Galaxies Christopher Fuse, Pamela Marcum, Michael Fanelli Isolated galaxies provide a unique means of assessing the evolution of galactic systems. Extremely isolated galaxies define the zero-interaction baseline for comparative studies of galaxy evolution. Here we present results for a sample of isolated early-type galaxies (IEGs) in the local universe. Candidate IEGs were identified using the optical imaging data from Release 1-5 of the Sloan Digital Sky Survey (SDSS). Objects are selected according to strict isolation criteria: IEGs must be separated by at least 2.5 Mpc from any neighboring non-dwarf companion galaxy (M$_{V} \quad > \quad -$16.5 mag). These criteria insure that the IEGs have never\textbf{\textit{ }}interacted with another existing galaxy since formation. We have combined SDSS images in the u,g,r filters to improve the signal-to-noise ratio. The stacked images permit a more robust determination of the morphology and photometric structure of the candidate galaxies. The images are interpreted using annular surface photometry and a bulge/disk decomposition technique. Our sample defines a complete volume-limited population of extremely isolated early-type galaxies within a distance of 72Mpc. [Preview Abstract] |
Friday, October 6, 2006 12:06PM - 12:18PM |
AP1.00009: A Photometric Investigation and Examination of Superhumps of V795 Her Daniel Malutich, Richard Olenick, Irina Voloshina We present new photometric data, taken at the Crimean Laboratory of Sternberg Astronomical Institute and University of Dallas, on the suspected intermediate polar V795 Her. Photometry reveals a period of 0.1155 days. This period, when compared with past observations, shows a slight modulation and even a complete disappearance in mid-1990. Light curves of V795 Her are also shown to demonstrate some superhump activity. Superhumps as the possible result of accretion disk precession are discussed. [Preview Abstract] |
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