Digital Commons Network^™

Momentum-Space Engineering Of Gaseous Bose-Einstein Condensates, Mark Edwards, Brandon Benton, Jeffrey Heward, Charles W. Clark

Department of Physics and Astronomy Faculty Publications

We show how the momentum distribution of gaseous Bose-Einstein condensates can be shaped by applying a sequence of standing-wave laser pulses. We present a theory, whose validity was demonstrated in an earlier experiment [L. Denget al., Phys. Rev. Lett. 83, 5407 (1999)], of the effect of a two-pulse sequence on the condensate wavefunction in momentum space. We generalize the previous result to the case of N pulses of arbitrary intensity separated by arbitrary intervals and show how these parameters can be engineered to produce a desired final momentum distribution. We find that several momentum distributions, important in …

Vlt Observations Of Ngc 1097'S “Dog-Leg” Tidal Stream: Dwarf Spheroidals And Tidal Streams, P. Galianni, F. Patat, James L. Higdon, S. Mieske, P. Kroupa

Department of Physics and Astronomy Faculty Publications

Aims. We investigate the structure and stellar population of two large stellar condensations (knots A & B) along one of the faint optical “jet-like” tidal streams associated with the spiral NGC 1097, with the goal of establishing their physical association with the galaxy and their origin.

Methods. We use the VLT/FORS2 to get deep V-band imaging and low-resolution optical spectra of two knots along NGC 1097's northeast “dog-leg” tidal stream. With this data, we explore their morphology and stellar populations.

Results. Spectra were obtained for eleven sources in the field surrounding the tidal stream. The great …

The Energetics Of Molecular Gas In Ngc 891 From H2 And Far-Infrared Spectroscopy, G. J. Stacey, Vassilis Charmandaris, F. Boulanger, Yanling Wu, F. Combes, S. J. U. Higdon, J. D. T. Smith, T. Nikola

Department of Physics and Astronomy Faculty Publications

We have studied the molecular hydrogen energetics of the edge-on spiral galaxy NGC?891, using a 34 position map in the lowest three pure rotational H2 lines observed with the Spitzer Infrared Spectrograph. The S(0), S(1), and S(2) lines are bright with an extinction-corrected total luminosity of ~2.8 × 107 L ?, or 0.09% of the total-infrared luminosity of NGC?891. The H2 line ratios are nearly constant along the plane of the galaxy?we do not observe the previously reported strong drop-off in the S(1)/S(0) line intensity ratio in the outer regions of the galaxy, so …

Dark Matter Halos And Evolution Of Bars In Disk Galaxies: Varying Gas Fraction And Gas Spatial Resolution, Jorge Villa-Vargas, Isaac Shlosman, Clayton Heller

Department of Physics and Astronomy Faculty Publications

We conduct numerical experiments by evolving gaseous/stellar disks embedded in live dark matter halos aiming at quantifying the effect of gas spatial resolution and gas content on the bar evolution. Three model sequences have been constructed using different resolutions, and the gas fraction has been varied along each sequence within the range of f g = 0%-50%, but keeping the disk and halo properties unchanged. We find that the spatial resolution becomes important with an increase in the gas content. For the higher resolution model sequences, we observe a bimodal behavior in the bar evolution with respect to the gas …

Restructuring Introductory Physics By Adapting An Active Learning Studio Model, Delena Bell Gatch

Department of Physics and Astronomy Faculty Publications

Despite efforts to engage students in the traditional lecture environment, faculty in Georgia Southern University’s Physics Department became dissatisfied with lecture as the primary means of instruction. During the fall semester of 2006, our department began adapting the studio model to suit the needs of introductory calculus-based physics students at our institution. A studio course seamlessly integrates the lecture and laboratory courses into a single course, devoting much of the class time to active, collaborative, student-centered learning. An emphasis was placed on replacing traditional lectures with interactive, technology enriched class periods designed around the various learning styles. New teaching materials …

Why Are Ring Galaxies Interesting?, James L. Higdon, Sarah J.U. Higdon

Department of Physics and Astronomy Faculty Publications

Compared with ordinary spirals, the ISM in ring galaxies experiences markedly different physical conditions and evolution. As a result, ring galaxies provide interesting perspectives on the triggering/quenching of large scale star formation and the destructive effects of massive stars on molecular cloud complexes. We use high resolution radio, sub-millimeter, infrared, and optical data to investigate the role of gravitational stability in star formation regulation, factors influencing the ISM's molecular fraction, and evidence of peculiar star formation laws and efficiencies in two highly evolved ring galaxies: Cartwheel and the Lindsay-Shapley ring.

Restructuring Introductory Physics By Adapting An Active Learning Studio Model, Delena Bell Gatch

Department of Physics and Astronomy Faculty Publications

Despite efforts to engage students in the traditional lecture environment, faculty in Georgia Southern University’s Physics Department became dissatisfied with lecture as the primary means of instruction. During the fall semester of 2006, our department began adapting the studio model to suit the needs of introductory calculus-based physics students at our institution. A studio course seamlessly integrates the lecture and laboratory courses into a single course, devoting much of the class time to active, collaborative, student-centered learning. An emphasis was placed on replacing traditional lectures with interactive, technology enriched class periods designed around the various learning styles. New teaching materials …