Session AB - Astronomy and Space Physics.
MIXED session, Friday morning, October 05
SWR L1, Sid W. Richardson Building

[AB.001] Coupled Ion-Neutral Motions in the Upper Atmosphere

In the upper atmosphere charged and neutral particles interact with each other and affect the dynamics and density distributions of each species. The charged particles are highly magnetized with motions perpendicular to the magnetic field dominated by electric fields and motions along the magnetic field influenced by pressure gradients and collisions with neutral gas. The neutral gas motion is dominated by heat sources from the Sun and the magnetosphere, and modified by collisions with ions. Large changes in the charged particle distributions occur from day to night leading to a charged particle layer in the ionosphere that is unstable to gravitational over-turning. The resulting instabilities are detrimental to the performance of space-ground radio communications. We will describe how a new observation program will increase our understanding of coupled ion-neutral motions in the upper atmosphere and thus our ability to specify and predict when and where plasma instabilities will occur.

[AB.002] HI Properties of Loose Groups

We present results from single-dish 21-cm HI line observations of 15 spiral-dominated loose groups of galaxies, made at the Nançay radio observatory. The galaxy groups have been selected to represent 2 different categories: groups showing optical evidence of galaxy interaction (``interacting'' sample), and groups showing no obvious morphological disturbances among their members (``control'' sample). We find statistically significant differences in some of the global HI properties (mass, rotation curves, presence of intragroup gas) between the 2 samples. These results possibly implicate a more advanced stage of dynamical evolution for the interacting sample.

[AB.003] Surface Brightness Profiles and Fine Structure of Isolated Elliptical Galaxies

Elliptical galaxies are thought to be the result of merger processes and are found predominantly in high-density regions of the universe. Because galaxy collisions are commonplace in the dense environment of clusters, distinguishing which characteristics of elliptical morphology in cluster members are caused by environment vs initial conditions is difficult, as is establishing the timescales over which merger-induced fine structure persists. These limitations make isolated elliptical galaxies particularly valuable for answering the above questions. In our study, we have defined isolated elliptical galaxies as separated by at least 2.5 Mpc from any other galaxy with M_V < -16.5. This separation precludes interaction with galaxies of similar luminosity known to be in the isolated elliptical’s environment over a Hubble time. We have verified this level of isolation for 6 elliptical galaxies in the northern hemisphere of the sky. We have performed isophotal analysis and unsharp masking on these objects to search for the presence of fine structure. We compare our results to those published for elliptical galaxies in more clustered environments.

[AB.004] Structure, Kinematics, Spectra, and Polarization of Parsec-scale Jets in Lobe-dominated Quasars

We report on recent centimeter-wavelength VLBI observations of parsec-scale jets in the nuclei of lobe-dominated quasars (LDQs). Our complete sample of 25 LDQs is drawn from the revised 3CR survey. Space VLBI observations of 3C263 at very high resolution show a transverse-resolved jet. Phase-referenced VLBA images of the extremely faint nuclei in 3C9, 3C14, 3C432, and 4C16.49 all exhibit one-sided parsec-scale jets that are well-aligned with kiloparsec-scale jets. Multiple-epoch VLBI images of 3C207, 3C208, 3C212, 3C245, 3C249.1, and 3C263 reveal superluminal motion in all these objects; in some objects, the jet trajectory is clearly non-linear and different jet components have different speeds. Spectral VLBA images of 3C207, 3C212, 3C263, and 3C334 show flat-spectrum cores and steep-spectrum jets. Polarization VLBA images of 3C207 and 3C275.1 show ordered magnetic field structures in the innermost jet regions. These results are generally consistent with relativistic jet models and active galaxy unification scenarios.

[AB.005] Have Event Horizons Been Detected?

The detection of event horizons has recently been claimed, based upon a comparison of the quiescent x-ray luminosities of neutron stars (NS) and galactic black hole candidates (GBHC) in low mass x-ray binaries. The lower quiescent luminosities of GBHC were attributed to an advective accretion flow (ADAF) through an event horizon. Since there are difficulties with the ADAF model and the similar quiescent emissions of NS appear to be at least partially magnetospheric in origin, the possibility that GBHC may possess magnetic fields needs to be considered. The existing observational data appear to be consistent with magnetospheric models. This possibility needs to be rejected before accepting a model dependent detection of event horizons.

[AB.006] A SCALING LAW FOR ORGANIZED MATTER IN THE UNIVERSE

The field of astrophysics has undergone some recent exciting developments and debates. Some such debates involve the interpretation of redshift data demonstrating the acceleration of the Universe. Also the highly geometric walls of superclusters (1) -- of lumpy Universe remain unexplained where quasars and galaxies seem to be spread unevenly from red shift surveys. We demonstrate a scaling law from the rotating Schwartzschild solution using the Kruskal-Szekerer coordinates for cosmological, galactic and smaller black holes. The key to this technique is a conformal transformation of space-time which brings the infinity into a finite radius converging to a point. Argument is made for the relation of the Schwartzchild metric as compared to other metrical forms such as the Robinson-Walker, Kerr-Newman geometries etc.(2) Horizons are generated in non-terminating null geodesics. Some recent observations by the Wide Field Planetary Camera 2 of the Hubble Space Telescope of Supernova SN1987A and Nebula MyCn18 display certain structures that relate to the plasma state field. (3) We will demonstrate our new scaling law and discuss possible explanations of the missing mass of the Universe in terms of vacuum state, polarizable, nonlinear structures. Some speculations on solar dynamics will be made.

1. Battaner, The Fractal Octahedron Network of the Large Scale Structure, Astrophysics abstract, Astro-ph/9801276, January 28, 1998, http://xxx.lanl.gov/abs/astro-ph/9801276.

2. E.A. Rauscher, A Unifying Theory of Fundamental Processes, UCB-LBNL Press, UCRL-20808, July, 1971

3. NASA, Press release no. STScI-PR 94-22, 1994 and no. STScI-PRC96-1996

Part A of program listing