January 25, 2005 Rob Kennicutt University of Arizona \Nearby Galaxies as Revealed by the Spitzer SINGS Legacy Project The Spitzer Infrared Nearby Galaxies Survey is a comprehensive multi-wavelength imaging and spectroscopic survey of 75 nearby galaxies. It is designed to provide definitive information on the large-scale star formation processes in galaxies and on the interaction of young stars with the surrounding interstellar medium. The early results from SINGS reveal the enormous diversity of infrared morphologies and spectral energy distributions (SEDs) along the Hubble sequence and as functions of galaxy mass and metallicity. Our current analyses are focused on detailed comparisons of UV, visible, infrared, and radio star formation rate indicators within individual galaxies, quantifying the differences in infrared SEDs and extinction properties within and between galaxies, and compiling a base set of reference image and spectral libraries for cosmological applications. |
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February 1, 2005 Lynn Jones Eaton University of Texas Active Learning Techniques "Active Learning" is, in short, anything that students do in a classroom other than merely passively listening to an instructor's lecture. Active learning techniques enhance lectures and actively engage students in the learning process. Techniques will be shared and demonstrated. |
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February 8, 2005 Frederick Chang University of Texas Information Security: What You Need to Know Today Unfortunately, viruses, worms, spyware, denial of service attacks and computer network compromises, in general, have become a way of life. As a result the industry has produced a blizzard of software and hardware tools to help protect our computers and networks from malicious attackers. Is the problem getting any better? This talk will provide some perspectives on the problem and challenges facing end-users today and will offer some practical recommendations. Additionally, the talk will introduce UT’s new Center for Information Assurance and Security and briefly describe its mission and objectives. |
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February 15, 2005 Michael Gaffey University of North Dakota Mineralogical and Compostional Characterizations of Asteroids: Why? How? What? Asteroids represent the surviving remnants of the planetesimal population which once filled the inner solar system and from which the terrestrial planets were accreted. Most of the chemical and geological evolution of the asteroid parent bodies occured within the first ten million years of solar system history. The properties of the planetesimals established the initial thermal properties of terrestial proto-planets Asteroids and their meteorite samples have recorded the chemical environment of the solar nebula, the early evolution of the Sun, and the collisional environment in the inner solar system. Sophisticated compositional and mineralogical characterizations of asteroids provide the basis for revealing these diverse perspectives on solar system history. Our research group has focused significant efforts on the development of observing protocols and data reduction procedures to optimize the quality of asteroid spectral data obtained with low-resolution near-infrared spectrographs. Such data is currently leading to significant improvements in our understanding of the formation epoch and the early solar system, of the relationships between asteroids and meteorites, and of the impact hazard by near-Earth objects. |
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February 22, 2005 Andrew Blain California Institute of Technology The Nature and Environments of Ultraluminous High-Redshift Galaxies Ground-based submillimeter-wave surveys have detected a significant population of very luminous distant galaxies. I will describe the search to uncover their properties, and their contribution to the complete picture of galaxy formation. In particular, I will describe the first steps to probing their spatial distribution, and the pospects for understanding the processes that lead to their very high luminosities, possibly biased into specific regions, and the prospects for using Spitzer and future facilities to study them in detail and compile larger samples. |
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March 1, 2005 Rosie Wyse Johns Hopkins University The Stellar Initial Mass Function Long Ago and Far Away The Stellar IMF at high redshift is of great importance for a wide range of astrophysical problems. There are two complimentary approaches to the determination of the IMF long ago and far away: one is to observe directly high redshift objects, and attempt inferences on the stellar IMF from the integrated spectrum and photometry, while the second approach analyses the fossil record in old stars at low redshift. The characterization of the stellar IMF in external galaxies, compared to that in the Milky Way, is a crucial step in deciphering the important physical processes that determine the distribution of stellar masses under a range of different physical conditions. The low mass stellar IMF at the high redshifts at which these stars formed is directly accessible through star counts, plus a mass-luminosty relation. The high-mass IMF at these high reshifts is constrained by the chemical signatures in the low mass stars that were enriched by the supernoave from the high mass stars. I will discuss both ends of the IMF at high redshift, in an external galaxy. I will also discuss a new survey for eclipsing low-mass binaries, to calibrate better the mass-luminosity relation. |
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March 8, 2005 Tsvi Prian California Institute of Technology Gamma-ray Bursts: An Enigma and a Tool |
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March 22, 2005 Steve Squyres Cornell University Science Results from the Mars Exploration Rover Mission |
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March 29, 2005 Andrea Ghez UCLA Unveiling a Supermassive Black Hole at the Center of our Galaxy The proximity of our Galaxy's center presents an opportunity to build a case for a supermassive black hole and to study the black hole's environment and its effects thereon with much higher spatial resolution than can be brought to bear on any other galaxy. After almost a decade of astrometry from diffraction- limited speckle imaging at the W.M. Keck 10m telescope, we have moved the case for a supermassive black hole at the galactic center from a possibility to a certainty; this is based on our recent ability to determine the orbits of individual stars, which confines the central dark mass of 3.7 million times the mass of the sun to within 45 AU (1 AU = the Earth-Sun distance), or equivalently, 600 Schwartzschild radii. With the advent of adaptive optics, which have significantly expanded out studies of the Galaxy's central black hole through the addition of diffraction-limited spectroscopy and deep imaging at wavelengths other than 2.2 microns. Spectroscopy has revealed that the stars orbiting in such close proximity are apparently massive and young; the origin of the stars is difficut to explain, given the strong tidal forces, and may provide key insight into the growth of the central black hole. Thermal infrared imaging (3.8 microns) has led to the direct detection of plasma associated with the black hole. This source is variable on timescales as short as 40 min, implying that the emission arises quite close to the black hole, within 5 AU, or 80 Schwartzschild radii. This provides a new, constantly accessible window into the physical conditions of the plasma in close proximity to the central black hole. |
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April 22, 2005
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April 26, 2005 Roger Davies Oxford University Galaxy Evolution Through the Eyes of SAURON The SAURON integral field spectrograph on the William Herschel Telescope has completed a survey of a representative sample of early-type galaxies over a range of luminosity, environment and Hubble type. I will present results on their stellar kinematics, make dynamical estimates of mass-to-light ratio, report on the distribution & kinematics of the ionized gas, and characterize the stellar population in terms of age, metallicity and mass-to-light ratio. I will discuss the implications of these results for dark matter in in galaxies, their star formation and assembly history. |
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May 3, 2005 Eiichiro Komatsu and Dan Jaffe University of Texas The Cosmic Inflation Probe Study We will discuss a concept for the Cosmic Inflation Probe (CIP)-a proposed space experiment with significant UT participation. The development of the concept of Inflation two decades ago was a critical event in the history of Big Bang cosmology. Inflation essentially saves the Big Bang by resolving the most important problems: the flatness problem, the smoothness problem, and the growth of structure. Inflation is what powers the Big Bang but yet we know very little about it: there are hundreds of inflation models that fit within the current observational constraints. The Universe in the matter-dominated era does, however, contain echoes of the inflation epoch which encode sufficient information about the inflaton potential to provide a much more detailed picture of inflation physics. CIP will precisely measure the power spectrum of the matter distribution at z=3-6.5 across a large range of spatial scales to produce the best observational constraints on the expansion history of the universe during inflation, thereby narrowing in on the underlying physics. We will describe the physical basis for our experiment, the instrument design, and the mission plan. |