Weekly Calendar of Events

NOVEMBER 3 - 7, 2014


Noon: Solar, Stellar, and Planetary Sciences Division Seminar. "Constraining Exoplanet Compositions via Host Star Abundances," Johanna Teske, Carnegie-DTM. Pratt Conference Room.

Abstract: It is an open and actively researched question how/to what extent the presence and chemical compositions of planets correlate with those of their host stars, beyond the well-known giant planet-metallicity correlation. Particularly interesting is the relative importance of elements like C, O, Mg, or Si in the formation and heavy element enrichment of giant planets. The C/O ratio can be indicative of planetary formation history and location, and these are currently the most promising elements for measurement in both star and exoplanet atmospheres. Giant planet formation may be (more strongly) regulated by the presence of more refractory elements, like Si and/or Mg, if cores are dominated by rocky rather than icy material. The formation of small planets does not seem to show the same overall dependence on host star metallicity, but studies of solar twins and analogs suggest the formation of small planets may still imprint a signature on their host star abundances. I will present results of ongoing high resolution, high S/N spectroscopic studies of host star abundances to investigate how/to what extent planet composition, atmospheric and interior, is dependent on host star composition. I will also highlight why binary host stars are a valuable opportunity for disentangling how an individual star's atmosphere may be affected by the formation of planets and its broader position in/motion through the Galaxy.


1:00 pm: Institute for Theory and Computation (ITC) Seminar. "Hot Jupiters from Coplanar High-eccentricity Migration," Cristobal Petrovich, Princeton University; and, "Why do Galaxies Stop Forming Stars? Evidence for Quenching of Central Galaxies via Black Hole Growth," Asa Bluck, University of Victoria. Pratt Conference Room.


11:00 am: Optical and Infrared Astronomy Division Seminar. "The Nature of Star Formation Quenching in Unlikely Sources," Dr. Katherine Alatalo, Infrared Processing and Analysis Center, California Institute of Technology. Pratt Conference Room.

4:30 pm: Joint ITAMP/HQOC Quantum Sciences Seminar. "Inducing Photonic Transitions for Enabling Next Generation Silicon Photonics," Michal Lipson, Cornell University. Tea served at 4:00 after short student talk. Jefferson 250, Department of Physics, Harvard University.

Abstract: We show that photonic transitions enables novel functionalities on-chip including: CMOS compatible isolators (critical for on-chip networks) , ultra-high speed modulators (critical for high bandwidth datacom) as well as effective magnetic field for photons.


11:00 am: Institute for Theory and Computation (ITC) Colloquium. Speaker: Prof. Eve Ostriker, Princeton University. Pratt Conference Room.

4:00 pm: Colloquium. Bok Prize Lecture: "New Insights into Astrophysical Turbulence," Dr. Brant Robertson, University of Arizona. Preceded by tea at 3:30 pm. Phillips Auditorium.

Abstract: Turbulence influences the properties of astrophysical fluids on a wide range of scales, from protoplanetary disks to the outskirts of galaxy clusters, and governs the critical process of star formation in galaxies like the Milky Way. While the theory of incompressible, subsonic turbulence benefits from a rich history spanning more than half a decade, the theory of supersonic turbulence in astrophysical contexts remains work in progress. Aided by large-scale numerical simulations, much of the theoretical success in modeling supersonic isothermal turbulence involves a coarse description of its statistical properties. After reviewing the theory of turbulence and its relevance for astronomical observations, I will present a fundamentally new framework for thinking about supersonic turbulence that focuses on describing the properties of shocked, dense regions. This new approach benefits from a direct connection with the astrophysics of star formation, and makes verifiable predictions for the structure of star forming clouds. I will conclude by discussing new computational methods engineered to tackle problems like supersonic turbulence in astrophysical contexts.


12:30 pm: Radio and Geoastronomy Division Lunch Talk. "Improving the Direction-Dependent Gain Calibration of Radio Telescopes," Andre Young. Room M-340, 160 Concord Avenue.

Abstract: Utilizing future radio telescopes, such as MeerKAT and the Square Kilometre Array (SKA) to their full potential will require calibrating for various direction-dependent effects, including the radiation pattern of each of the antennas in the array. This requires an accurate characterization at the time of an observation of these patterns, which due to manufacturing tolerances and changing environmental conditions exhibit both inter-element and time variation. Furthermore, fundamental limits in imaging as well as practical time constraints require this to be done with the minimal amount of measurement data. In this talk I will discuss an approach towards such accurate characterization based on using low-order parameterize beam models.

The Calendar is prepared by the Web Services Group. Entries may be submitted via email to weekly_cal@cfa.


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