Colloquia
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.
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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.
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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.
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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.
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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.
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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)
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Previous colloquia series: Fall 2002 Spring 2003 Fall 2003
Contact for program information:
Daniel Dale (ddale @ uwyo.edu)
Updated on Jul 25, 2003
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