Friday, October 17 - PM |
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1:15-5:00 |
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Session 2: Formation and Evolution of Planets GEO 2.216 Neal Evans Session Chair |
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1:15 |
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Planet Embryos in Vortex Wombs GEO 2.216 Joseph Barranco One of the enduring puzzles in the formation of planetary systems is how millimeter-sized dust grains agglomerate to become kilometer-sized, self gravitating planetesimals, the "building blocks" of planets. One theory is that the dust grains settle into the mid-plane of the protoplanetary disk (thin, cool disk of gas and dust in orbit around a newly forming protostar) until they reach a critical density that triggers a gravitational instability to clumping. However, turbulence within the disk is likely to stir up the dust grains and prevent them from reaching this critical density. A competing theory is that dust grains grow by pair-wise collisions, forming fractal structures. It is unclear, however, how robust such structures would be to successive collisions. A new and exciting theory is that vortices in a protoplanetary disk may capture dust grains at their centers, "seeding" the formation of planetesimals. We are investigating the dynamics of 3D vortices in protoplanetary disks with a parallel spectral code on the Blue Horizon supercomputer. Some of the lingering questions we address are: What is the structure of 3D vortices in a protoplanetary disk? Are they columns that extend vertically through the disk, through many scale heights of pressure and density? Or are they more "pancake-like" and confined to the mid-plane? Are the vortices stable to small perturbations, such as vertical shear? Are 3D vortices robust and long-lived coherent structures? Do small vortices merge to form larger vortices the way vortices on Jupiter do? |
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2:00 |
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Circumstellar Disks: Past, Present, and Future GEO 2.216 Michael Liu Circumstellar disks are thought to play a central role in the formation of stars. We review our current observational understanding of the physical properties and evolution of disks, as well as the connections with the formation of extrasolar planets and brown dwarfs. We also describe a few of the imminent new instrumental capabilities which should produce substantial advances in our knowledge of disks. |
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2:45-3:10 |
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Coffee |
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3:10 |
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The Future of Extrasolar Planet Detection and
Characterization GEO 2.216 Gabriela Mallen-Ornelas The discovery of giant extrasolar planets in the mid-1990's using radial velocity techniques heralded a new era in the study of planet formation. To date, more than 100 planetary systems have been detected around sun-like stars, and the surprising variety in the characteristics of these systems has shown that planetary systems can be radically different from our own. A dramatic step forward in the characterization of individual extrasolar planets took place in 1999 with the discovery of transits of the extrasolar planet HD209458b, the measurement of its unexpectedly-large radius, and the subsequent detections of sodium in its atmosphere and the presence of an exosphere. The upcoming decade promises to bring many exciting discoveries as a result of improvements in instrumentation, the refinement of new techniques (such as the transit search technique), and the launch of several space observatories (such as Kepler, Corot, Eddington, and SIM) dedicated to the study of extrasolar planets. |
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3:55-4:20 |
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Panel Discussion GEO 2.216 UT Panel Members: Nairn Baliber Thomas Greathouse Jacqueline Silacci Ted von Hippel |
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4:20 |
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Guest of Honor Colloquium: The Future of Ground-Based Optical and Infrared Astronomy: Some Observations and Some Ironies GEO 2.216 David Lambert Director, McDonald Observatory Frank Bash Frank N. Edmonds Regents Professor and Outgoing Director of McDonald Observatory The future of ground-based optical and infrared astronomy involves larger and larger telescopes, the development of challenging technologies like active and adaptive optics, instruments for the giant telescopes, an evolving role for the federal government in what has previously been an activity of the independent observatories and an attempt to complement but not compete with NASA's plans. I will attempt to gaze through these murky waters. |
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7:00 |
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(Public Talk) AAS 2nd Century Lecture: Einstein's Biggest Blunder? The Case for Cosmic "Antigravity" WEL 2.224 Alex Filippenko In 1998, observations of very distant exploding stars provided intriguing evidence that the expansion of the Universe is speeding up with time, rather than slowing down as expected. New, completely independent data greatly support this conclusion, which resurrects the idea of a long-range "antigravity" effect first proposed by Albert Einstein and later renounced as his "biggest blunder." The vacuum appears to be filled with "dark energy," perhaps consisting of quantum fluctuations out of nothing, whose overall effect is repulsive! The discovery of the accelerating universe was voted the top "Science Breakthrough of 1998" by Science magazine, and was the cover story in the 25 June 2001 issue of TIME magazine. |
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