Colloquia Schedule Spring 2016
Colloquia are on Tuesdays (unless otherwise indicated) at 3:30 pm in RLM 15.216B
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"Spirals, Gaps, and Cavities: Signposts of Planets in Protoplanetary Disks?" LBNL/Berkeley host: Adam Kraus |
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"The Key Influence of AGB Stars on the Evolution and Global Properties of Galaxies" NASA Goddard host: Kristen McQuinn |
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"CAMPARE and Cal-Bridge: Two Synergistic Programs Forming a Successful New Model for Promoting Participation of Women and Underrepresented Minority Students in Astronomy" California State Polytechnic University, Pomona host: William Cochran |
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"Exoplanet Atmospheres in High Resolution" Harvard-Smithsonian Center for Astrophysics host: Daniel Jaffe |
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"The Dynamical Evolution of Young Stellar Complexes in the Milky Way" McMaster University, Hamilton, ON host: Natalie Gosnell |
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"The Evolution of Galaxy Structural Properties" Rutgers University, Downsbrough Chair in Astrophysics host: Shardha Jogee |
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"A PHAT New Measurement of the High-Mass Stellar IMF" The initial mass function (IMF) for stars above ~1 Msun is essential to testing and validating theories of star formation, constraining chemical enrichment models, the frequency of core-collapse supernovae, and interpreting the stellar populations of galaxies across cosmic time. Yet, despite more than 60 years of research, observational constraints on the high-mass IMF remain remarkably uncertain. Widely used high-mass IMFs (e.g., Kroupa) have associated uncertainties approaching an order-of-magnitude, making it virtually impossible to determine if the high-mass IMF varies with respect to environment (e.g., metallicity or star formation intensity) or is "Universal". In this talk, I will present the most precise measurement of the high-mass IMF to date. Using ~100 young, resolved star clusters in M31 imaged as part of the Panchromatic Hubble Andromeda Treasury (PHAT) survey, we find the high-mass IMF slope to be Gamma=1.45+/-0.03. Compared to the canonical Kroupa IMF (Gamma=1.3+/-0.7), the high-mass IMF in M31 is 0.15 dex steeper (i.e., fewer massive stars) and represents a factor of ~20 improvement in precision. There are no significant trends between the cluster IMF slopes and their ages, masses, and sizes, indicating that the IMF is remarkably "Universal" in this sample of ~100 clusters. I will illustrate some of the broader implications of a steeper IMF slope (e.g., on star formation rate indicators, core-collapse supernovae rates) and will conclude by discussing the prospects for precision IMF measurements in other environments. UC Berkeley/University of Washington host: Michael Boylan-Kolchin |
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"The Role of Dwarf-Dwarf Galaxy Interactions in Galaxy Assembly" NRAO/University of Virginia host: Kristen McQuinn |
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No colloquium scheduled. (Spring Break) |
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"Exploring the z~2.3 Cosmic Web with 3D Lyman-Alpha Forest Tomography" UC Berkeley/LBNL host: Caitlin Casey |
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"Understanding Galaxy Evolution with Massive Starburst Galaxies" University of Iowa host: Caitlin Casey |
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"Implications from the Detection of the Binary Black Hole Inspiral GW150914" University of Texas Rio Grande Valley host: J. Craig Wheeler |
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Stellar Seminar talk Date/Time: Wed., 12 Noon: "Title: TBA" David Yong (Stellar Tinsley Scholar) Mt. Stromlo Observatory, Australia host: Fritz Benedict |
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"The Calm Before the Storm: Exploring the Post Accretionary Doldrums Prior to the Late Heavy Bombardment" William F. Bottke (Planetary Tinsley Scholar) Southwest Research Instutite, Boulder, Colorado host: Mike Endl/Judit Ries |
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"Disk Galaxy Assembly Across Cosmic Time: Combining Magnitude-limited Survey with Gravitational Lensing" Tiantian Yuan (Exgal Tinsley Scholar) Australia National University host: Chao-Ling Hung |
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"The Discovery and Characterization of the Y Dwarfs" University of Toledo host: Brendan Bowler |
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"What can Binaries tell us about Planet Formation?" Kaitlin M. Kratter (ISM Tinsley Scholar) Steward Observatory, University of Arizona host: Adam Kraus |
Visitors to the Department of Astronomy can find detailed information and maps on our Visiting Austin Page.
Please report omissions/corrections to: G. Orris at argus@astro.as.utexas.edu.
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15 April 2016
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