Department of Physics and Astronomy


University of Wyoming Physics & Astronomy Colloquium Series

Fridays -- 4:10 PM -- Prowse Room 234

Pre-Colloquium tea served at 3:45 in the Cinnamon Room, PS 237

Tentative Spring 2004 Schedule

Jan 30 Jonathan Tan (Princeton)
Star Formation in Disk Galaxies: from GMCs to Star Clusters

What sets the star formation rate in disk galaxies? What are the initial conditions of regions of giant molecular clouds (GMCs) that will form star clusters and how do they arise? Massive stars form in these regions, but is the mechanism similar to that of isolated, low-mass star formation, or do dynamical interactions between stars make this picture obsolete? How do hundreds of O and B stars, producing strong feedback, form together in Super Star Clusters in a volume of just a few cubic parsecs? I shall present theoretical models that attempt to address these questions and review observations that test them.

February 6 Matthias Schoeck (Caltech)
Atmospheric turbulence characterization with the Keck and Palomar adaptive optics systems

Adaptive optics (AO) systems are used at astronomical observatories to correct for the distortions introduced to the incoming light by atmospheric turbulence. Ideally, the full diffraction-limited capabilities of the telescopes are thus restored. In reality, the performance of the AO system depends on the turbulence conditions at the given time. Real-time measurements of turbulence conditions are therefore highly desirable for performance analyses and improvements of AO systems. In this talk, I present the methods we have developed at the Keck and Palomar observatories to measure atmospheric turbulence parameters using the wavefront sensors of the AO systems themselves.

February 27 Paul Johnson (Wyoming)
Real-Time Biodetection of Pathogenic Microorganisms with CCD Imaging

Infections from foodborne and waterborne pathogens constitute a major world health problem. Foodborne microbial pathogens account for approximately 7 million illnesses and 9,000 deaths in the U.S. annually, with an estimated economic loss of at least $6 billion per annum. A research program to develop an innovative solution to real-time detection of pathogens in food and water will be presented. This technique is based on CCD imaging of a flowing food/water matrix in which pathogenic cells have been labelled with fluorescent molecules. These molecules are excited with a laser and the resulting fluorescence is imaged with a CCD camera.

March 26 Jessica Rosenberg (Colorado)
The Topology of Gas in the Universe

In recent years simulations have been able to show the evolution of the large-scale structure of gas and dark matter in the Universe. The simulations indicate that there is a web of lower density gas strung between the galaxies and galaxy clusters. To understand the evolution of galaxies and the large-scale structure, we must understand how these higher density regions are connected with the lower density intergalactic gas. Merging, accretion, and outflows are all important processes in this gas exchange. I will discuss our observations of gas in galaxies and in the cosmic filaments. In addition I will talk about what we know about the links between the galaxies and the intergalactic medium.

April 23 Lisa Kewley (CfA)
Star Formation Rate Discrepancies & the Madau Plot

I present results from our investigation into the H-alpha, infrared, and [OII] as star formation rate (SFR) indicators for local and high-z samples. In local samples, correction of the SFR(H-alpha) for extinction using the Balmer decrement and a classical reddening curve both reduces the scatter in the SFR(IR)-SFR(H-alpha) correlation and results in a much closer agreement between the two SFR indicators: within 10% for all Hubble types in the Nearby Field Galaxy Survey. This result suggests that the IR emission in these objects (including early types) results from a young stellar population. Comparisons between the Kennicutt [OII] and H-alpha SFR calibrations show that there are two significant effects which produce strong disagreement between SFR([OII]) and SFR(H-alpha): reddening and metallicity. Such a disagreement can appear as a function of redshift, contaminating cosmic star formation history studies (Madau plot). I present a new SFR([OII]) calibration which does not contain a reddening assumption, and includes an optional correction for metallicity. This new SFR([OII]) removes the previously observed discrepancy between the star formation history based on [OII] and the star formation history based on H-alpha.

April 30 Lakshmi Mohan (U. Colorado)
Tests of Lorentz Invariance with Atomic clocks

Lorentz Invariance has been the cornerstone of special relativity. Recently thoeries have been proposed suggesting violations of Lorentz invariance and experiments have come up that provide the strictest limits on these violations.We will discuss theories that incorporate Lorentz violations and possible experimental tests of these violations using atomic clocks.

May 7 Jason Verley (Sandia National Laboratories)

Previous colloquia series: Fall 2002 Spring 2003 Fall 2003
Contact for program information: Daniel Dale (ddale @

Updated on Jul 25, 2003