KICP Seminars & Colloquia, Winter 2011

Seminar schedule for Winter 2011
January 3, 2011
Astronomy Special Seminar
Michael Meyer
Institute for Astronomy, ETH, Zurich
Origins of Stars and Planets: 2020 Vision(s)   [Abstract]
January 5, 2011
Wednesday colloquium
Larry Widrow
Queen's University
Bars, Streams, and PAndAS: Galactic Dynamics and Hierarchical Clustering in the Nearby Universe   [Abstract]
January 7, 2011
Friday noon seminar
Bradford A Benson
University of Chicago
Observing the Evolution of the Universe through the CMB   [Abstract]
January 14, 2011
Friday noon seminar
Cynthia Chiang
Princeton University
Probing the Early Universe with CMB Polarization Measurements from SPIDER and Planck   [Abstract]
January 19, 2011
Astronomy Colloquium
Hui Li
AGNs, Small-Scale Dynamo and Magnetic Fields in Galaxy Clusters   [Abstract]
January 21, 2011
Friday noon seminar
Sam Waldman
Experimental Gravity with LIGO   [Abstract]
January 26, 2011
Wednesday colloquium
Akito Kusaka
The University of Chicago
First Result from QUIET   [Abstract]
January 27, 2011
Special seminar
Neelima Sehgal
Stanford University/SLAC
Cosmology from Sunyaev-Zel'dovich Galaxy Clusters Detected with the Atacama Cosmology Telescope   [Abstract]
January 27, 2011
Astronomy Special Seminar
Jacob Bean
Harvard University
The Small Star Opportunity to Find and Characterize Habitable Planets   [Abstract]
February 2, 2011
Open Group seminar
Charles Shapiro
Institute of Cosmology and Gravitation, Portsmouth
Connecting Probes of Dark Energy and Modified Gravity   [Abstract]
February 3, 2011
Astronomy Special Seminar
Diana Valencia
Observatoire de la Cote d'Azur
Characterizing Super-Earths   [Abstract]
February 4, 2011
Friday noon seminar
Keren Sharon
University of Chicago
Strong Lensing in Clusters of Galaxies: Using Nature's Largest Telescopes
February 9, 2011
Astronomy Colloquium
Juri Toomre
JILA, University of Colorado at Boulder
Joys of turbulent convection and dynamos in both stellar envelopes and cores   [Abstract]
February 10, 2011
Astronomy Special Seminar
Thayne Currie
NASA-Goddard Space Flight Center
Seeing Other Solar Systems in the Making: Direct Imaging and Spectroscopy of Planets and Planet-Forming Disks   [Abstract]
February 11, 2011
Friday noon seminar
Matt Kistler
New Constraints on the Highest-Energy Cosmic-Ray Electrons and Positrons   [Abstract]
February 16, 2011
Wednesday colloquium
Leonardo Senatore
Stanford University
Exploring the Beginning of the Universe.   [Abstract]
February 17, 2011
Astronomy Special Seminar
Lucas Cieza
Institute of Astronomy, University of Hawaii
Observing Planet Formation in Nearby Circumstellar Disks   [Abstract]
February 18, 2011
Friday noon seminar
Kohta Murase
Multi-Messenger Approach for Revealing Extragalactic High-Energy   [Abstract]
February 23, 2011
Astronomy Colloquium
Stanislav Boldyrev
University of Wisconsin - Madison
The physics of magnetohydrodynamics turbulence   [Abstract]
February 24, 2011
Astronomy Special Seminar
Dan Fabrycky
UCO/Lick Observatory
Planetary Systems from Kepler   [Abstract]
February 25, 2011
Friday noon seminar
Michael Cooper
UC Irvine
Understanding the Global Course of Galaxy Evolution at z < 1   [Abstract]
February 25, 2011
Astronomy Special Seminar
Martin Houde
University of Western Ontario
Characterizing Magnetized Turbulence in Molecular Clouds and Galaxies   [Abstract]
March 2, 2011
Astronomy Colloquium
Vikram Dwarkadas
University of Chicago
Blast from the Past: Hydrodynamic and X-ray Modeling of the Circumstellar Medium as Clues to Supernova Progenitors   [Abstract]
March 4, 2011
Friday noon seminar
Jeffrey M Kubo
Galaxy Clusters and Weak Lensing - a view from the Western Suburbs   [Abstract]
March 9, 2011
Wednesday colloquium
Dennis Zaritsky
University of Arizona
A New Twist on Galactic Structure   [Abstract]
March 16, 2011
Wednesday colloquium
Nir J. Shaviv
Racah Inst. of Physics, Hebrew University
Is the cosmic-ray positron excess evidence for Dark Matter Decay?   [Abstract]
March 18, 2011
Friday noon seminar
Jean-Christophe Hamilton
Laboratoire Astroparticule et Cosmologie
QUBIC: The QU Bolometric Interferometer for Cosmology   [Abstract]

  • January 5, 2011 | 3:30 PM | RI 480
    Bars, Streams, and PAndAS: Galactic Dynamics and Hierarchical Clustering in the Nearby Universe
    Larry Widrow, Queen's University

    The Local Group is a dynamic environment. Its two main constituents, M31 and the Milky Way, are continually accreting smaller galaxies. This process is beautifully captured in the Pan-Andromeda Archeological Survey, which is providing, in unprecedented detail, the structure and content of M31 and M33. Moreover, both M31 and the Milky Way are barred, which suggests that these galaxies are undergoing secular evolution. I will describe simulations that are designed to explore these and other phenomena. A numerical toolbox for generating flexible, equilibrium models of disk galaxies will also be presented.
  • January 26, 2011 | 3:30 PM | RI 480
    First Result from QUIET
    Akito Kusaka, The University of Chicago

    Cosmic microwave background (CMB) polarization is the ultimate probe of primordial gravity waves in the early universe, via the B-mode (or parity odd) signal on degree angular scales. A detection of such a signal would be strong evidence of the inflation scenario and represent indirect observation of a fundamentally new phenomenon near the grand unification energy scale. With its unique HEMT radiometer technology, QUIET is among the most competitive experiments aiming to detect such a signature in the CMB. QUIET has just completed its observation from October 2008 through December 2010, first with 43GHz receiver and then with 95GHz one, collecting over 10000 hours of data in total. In this talk, I will review the QUIET experiment and report the first result from QUIET using 3458 hours of data taken with the 43GHz receiver. The result is supported by analysis techniques such as cross correlation of the maps with different pointings and the blind analysis. Thoroughly estimated systematic errors, being the least of those reported to date, demonstrate systematic cleanness of QUIET and represent a good prospect for a future project.
  • February 16, 2011 | 3:30 PM | RI 480
    Exploring the Beginning of the Universe.
    Leonardo Senatore, Stanford University

    In the past few decades Cosmological observations have allowed us to explore the history of our universe and the nature of the Big Bang with greater and greater precision. They strongly suggest that our Universe started with a period of cosmic acceleration that we call Inflation. I will describe what we currently know about this initial epoch and how, thanks to the upcoming experiments, our knowledge about it might improve drastically, revealing us the dynamics that lead to it and making us extremely confident about the existence of such an epoch at the beginning of our Universe.
  • March 9, 2011 | 3:30 PM | RI 480
    A New Twist on Galactic Structure
    Dennis Zaritsky, University of Arizona

    Unlike the theory of stellar structure, which has a simple and intuitive outline, that of galactic structure is piecemeal and ad hoc. In fact, it has been difficult even to determine whether or not one should expect there to be such an analog. Numerical modeling of the problem grows ever more sophisticated and detailed in its efforts to match observations, suggesting that perhaps the problem is beyond any simple description. However, I will, using simple and general arguments, demonstrate that the global structure of galaxies of all sizes, masses, and morphological types can be described to a high degree using only two observational parameters. I will then explore the nature of those two parameters.
  • March 16, 2011 | 3:30 PM | RI 480
    Is the cosmic-ray positron excess evidence for Dark Matter Decay?
    Nir J. Shaviv, Racah Inst. of Physics, Hebrew University

    Recent measurements of the positron/electron ratio in the cosmic ray (CR) flux exhibits an apparent anomaly, whereby this ratio increases between 10 and 100 GeV. This has triggered significant excitement as it can be interpreted as evidence for dark matter decay. I will show instead that the standard source for cosmic rays, that of supernova remnants, explains this ''anomaly'' once one considers the actual inhomogeneous distribution of SNe in the disk. This also explains other cosmic ray characteristics, such as the energy dependence of the Boron to Carbon ratio.


  • January 7, 2011 | 12:00 PM | LASR Conference Room
    Observing the Evolution of the Universe through the CMB
    Bradford A Benson, University of Chicago

    Encoded within the polarization and fine-scale temperature anisotropy of the cosmic microwave background (CMB) are potential answers to fundamental questions about the nature of dark energy, the energy scale of Inflation, the evolution of the first stars and galaxies, and their effect on the growth of cosmic structures. Only recently have detector and focal plane sensitivities improved to a level to make these measurements possible. This has been evidenced by recent measurements from the South Pole Telescope (SPT), which reported two notable firsts: 1) the first detection of secondary CMB anisotropy, and 2) the first galaxy cluster catalog selected by their spectral distortion of the CMB, also known as the Sunyaev-Zel'dovich (SZ) effect. I will review recent cosmological constraints from the SPT, preview future results from the SPT survey and its polarization sensitive camera, SPTpol, and finally discuss the experimental challenges and scientific goals for the next generation of CMB experiments.
  • January 14, 2011 | 12:00 PM | LASR Conference Room
    Probing the Early Universe with CMB Polarization Measurements from SPIDER and Planck
    Cynthia Chiang, Princeton University

    The polarization of the cosmic microwave background (CMB) is a powerful tool for cosmology, encoding the history of the universe from inflation up to the era of structure formation. I will describe two experiments, SPIDER and Planck, that employ complementary strategies to measure CMB polarization with high precision over a wide range of angular scales. SPIDER is a balloon-borne multifrequency telescope with 0.5 degree resolution that is designed to map CMB polarization with high fidelity over ~10% of the sky. Planck is a satellite mission that has been operating since August 2009, and the High Frequency Instrument will yield four all-sky surveys at six frequency bands (100-857 GHz) with 4-10 arcminute resolution. SPIDER is optimized to constrain the amplitude of inflationary gravitational waves by searching for a B-mode polarization signature in a multipole range where the signal is expected to peak. Planck, in contrast, will effectively target the largest angular scales, which are sensitive to reionization history, and will produce cosmic variance limited measurements of E-mode polarization up to ell~1000. Together, the combination of SPIDER and Planck will produce a rich data set that will provide numerous insights into the history of the universe.
  • January 21, 2011 | 12:00 PM | LASR
    Experimental Gravity with LIGO
    Sam Waldman, MIT

    The direct detection of gravitational waves (GWs) offers a revolutionary new probe of the most energetic processes in the universe and a precision test of general relativity. The 4 km long LIGO interferometers have demonstrated the sub-attometer displacement sensitivity (< 10^{-18} m/ Hz^{1/2}) and continuous operation (> 75\% duty factor) needed to detect GWs out to the Virgo cluster, but none have yet been seen. Starting in 2008, we began construction of a 2nd generation of interferometers, Advanced LIGO, to increase the detector sensitivity and bandwidth by more than an order of magnitude. In this talk I will review the next five years of physics challenges and experiments involved in building and commissioning Advanced LIGO. We will discuss our plans to commission active seismic isolation systems with picometer displacement noise, low-loss passive isolation systems with mechanical quality factors >10^7, and Michelson interferometers with 750 kW of stored power. Together, these systems form a detector capable of detecting the 2x10^{-20} m GW signal from two black holes coalescing 6 billion light years away. We expect Advanced LIGO to detect the most powerful sources -- the merger of two compact objects such as neutron stars and black holes -- with rates from a few to many per year. The GW waveform, together with electromagnetic observations, will allow tests of the physics of black holes and general relativity. As the Advanced LIGO program continues, we will continue to improve the interferometer sensitivity using advanced integrated photonics, novel materials, and advanced quantum measurement techniques. I will conclude with a brief discussion of the Fermilab Holometer, an experiment that uses technology from LIGO to search for hypothetical two dimensional fluctuations in space-time coordinates known as holographic noise. The Fermilab Holometer uses two independent, 40 m long Michelson interferometers to measure correlated fluctuations in the positions of their beam splitters. The experiment is designed to have 5-sigma sensitivity to the Planck scale with a 30 minute integration time and could have results in late 2011.
  • February 4, 2011 | 12:00 PM | LASR Conference Room
    Strong Lensing in Clusters of Galaxies: Using Nature's Largest Telescopes
    Keren Sharon, University of Chicago
  • February 11, 2011 | 12:00 PM | LASR Conference Room
    New Constraints on the Highest-Energy Cosmic-Ray Electrons and Positrons
    Matt Kistler, Caltech

    The measured spectrum of cosmic-ray electrons/positrons can provide insight into the rich history of high-energy astrophysical processes near Earth. However, until quite recently, knowledge of this quantity could be called, at best, uncertain. Fortunately, needed clarity has been brought in the range of energies from ~10 GeV up to a few TeV by Fermi, PAMELA, and HESS, though for higher energies no measurements yet exist. I will address how we can extend our knowledge of the cosmic-ray electron population beyond the current high-energy frontier in order to improve our understanding of high-energy sources throughout the Galaxy.
  • February 18, 2011 | 12:00 PM | LASR Conference Room
    Multi-Messenger Approach for Revealing Extragalactic High-Energy
    Kohta Murase, CCAPP, OSU

    The origin of high-energy cosmic rays, especially ultra-high-energy cosmic rays (UHECRs), has been one of the biggest mysteries in physics and astronomy. The multi-messenger approach, using neutrinos and gamma rays as well as cosmic rays, is necessary in order to reveal the sources. Recently a Gton neutrino detector, IceCube, has been completed, and several Cherenkov gamma-ray telescopes as well as the gamma-ray satellite Fermi are now operating, so that the era of the multi-messenger observations is coming. The importance the multi-messenger approach is even greater if cosmic rays are transiently produced by bursts or flares and/or they are heavy nuclei rather protons, since cosmic rays experience long time delays and/or large deflections due to the cosmic magnetic fields. In this talk, we discuss characteristic signals from extragalactic astrophysical sources, which could be crucial for identifying the accelerators of UHECRs.
  • February 25, 2011 | 12:00 PM | LASR
    Understanding the Global Course of Galaxy Evolution at z < 1
    Michael Cooper, UC Irvine

    Evolution in the global galaxy population over the past 7 Gyr has been dominated by two principal trends: a dramatic decline in the average level of star-formation activity combined with a substantial growth in the stellar mass density within the red galaxy population. While both of these evolutionary trends are well measured at z < 1, the physical mechanisms responsible remain somewhat poorly understood. Using data from the DEEP2 Galaxy Redshift Survey in concert with complementary observations spanning UV to radio wavelengths, I will present recent results that directly constrain the physical processes driving the global transformation in galaxy properties at z < 1. In particular, I will discuss ongoing work to probe the cold gas component of star-forming galaxies at high redshift, which is providing direct constraints on the fuel supply for star formation when the Universe was less than half its current age. Finally, I will conclude by outlining the limitations of the current data sets and how they might be overcome with future ground- and space-based facilities.
  • March 4, 2011 | 12:00 PM | LASR Conference Room
    Galaxy Clusters and Weak Lensing - a view from the Western Suburbs
    Jeffrey M Kubo, Fermilab

    I will present results involving galaxy clusters and weak lensing using three different optical imaging surveys: the Deep Lens Survey, the Sloan Digital Sky Survey, and the SDSS Coadd. I will also present an update of this topic in the forthcoming Dark Energy Survey.
  • March 18, 2011 | 12:00 PM | LASR Conference Room
    QUBIC: The QU Bolometric Interferometer for Cosmology
    Jean-Christophe Hamilton, Laboratoire Astroparticule et Cosmologie

    One of the major challenges of modern cosmology is the detection of B-mode polarization anisotropies in the Cosmic Microwave Background. These originate from tensor fluctuations of the metric produced during the inflationary phase. Their detection would therefore constitute a major step towards understanding the primordial Universe. The expected level of these anisotropies is however so small that it requires a new generation of instruments with high sensitivity and extremely good control of systematic effects. We propose the QUBIC instrument based on the novel concept of bolometric interferometry, bringing together the sensitivity advantages of bolometric detectors with the systematics effects advantages of interferometry. The instrument will directly observe the sky through an array of entry horns whose signals will be combined together using an optical combiner. The whole set-up is located inside a cryostat. Polarization modulation will be achieved using a rotating half-wave plate and the images of the interference fringes will be formed on two focal planes (separated by a polarizing grid) tiled with bolometers. We show that QUBIC can be considered as a synthetic imager, exactly similar to a usual imager but with a synthesized beam formed by the array of entry horns. Scanning the sky provides an additional modulation of the signal and improve the sky coverage shape. The usual techniques of map-making and power spectrum estimation can then be applied. We show that the sensitivity of such an instrument is comparable with that of an imager with the same number of horns. We anticipate a low level of beam-related systematics thanks to the fact that the synthesized beam is determined by the location of the primary horns. Other systematics should be under good control thanks to an autocalibration technique, specific to our concept, that will permit the accurate determination of most of the instrumental parameters that would otherwise lead to systematics.


  • January 27, 2011 | 12:00 PM | LASR Conference Room
    Cosmology from Sunyaev-Zel'dovich Galaxy Clusters Detected with the Atacama Cosmology Telescope
    Neelima Sehgal, Stanford University/SLAC

    For the first time microwave surveys such as the Atacama Cosmology Telescope (ACT) and the South Pole Telescope (SPT) are detecting galaxy clusters through the Sunyaev-Zel'dovich (SZ) effect. Counts of galaxy clusters as a function of mass and redshift provide a powerful probe of structure growth and cosmology. I will discuss constraints on the matter power spectrum amplitude, sigma_8, and dark energy equation of state, w, from SZ cluster counts detected with ACT.


  • February 2, 2011 | 11:00 AM | LASR Conference Room
    Connecting Probes of Dark Energy and Modified Gravity
    Charles Shapiro, Institute of Cosmology and Gravitation, Portsmouth

    A battery of cosmological probes is needed to test Lambda-CDM or distinguish dark energy from modified gravity models. Probes made possible by surveys like DES and SDSS include type Ia supernovae, cosmic shear, galaxy cluster counting, baryon acoustic oscillations, the integrated Sachs-Wolfe effect (ISW), and redshift-space distortions (RSD). By breaking cosmological parameter degeneracies, these probes provide much tighter constraints together than they can separately. Also, when diverse probes with different systematics yield consistent results on a given measurement, that is strong evidence that we understand our experiments. The increasing precision and volume of cosmological data compels us to treat these probes as interconnected systems. For instance, galaxy clusters contribute to gravitational lensing, so we expect cluster counts and cosmic shear to be correlated within a single survey. Standard candles (detected optically or in gravitational waves) are randomly magnified by gravitational lensing, which weakens distance measurements. ISW and RSD measurements are also highly correlated since they probe the same underlying gravitational potential. I will discuss the implications of these probe connections. I will also introduce a "Multi-dimensional Consistency Test" which was developed to quantify the agreement (or disagreement) among DES probes measuring a common set of cosmological parameters.


  • January 19, 2011 | 3:30 PM | RI 480
    AGNs, Small-Scale Dynamo and Magnetic Fields in Galaxy Clusters
    Hui Li, LANL

    Galaxy clusters are important laboratories for cosmology and astrophysics. X-ray and radio observations of galaxy clusters have revealed a wealth of structures in association with extragalactic radio sources. Structures in the form of large-scale cavities and weak shocks provide a reliable gauge of the energy output of extragalactic radio jets launched by AGNs. Furthermore, they place interesting constraints on the nature of AGN outflows, especially on large scales. We will present 3-D MHD simulations of jets/lobes in the ICM and compare them with ~70 X-ray cavities as well as individual jet/lobe sources. In addition, we will present cosmological MHD simulations of galaxy cluster formation with AGN jets/lobes feedback and its implications for the origin and energetics of the cluster-wide magnetic fields. We demonstrate that the ICM turbulence is excited and sustained by the frequent mergers during the cluster formation. We quantify the available turbulent kinetic energy and nonlinear cascade rates. This turbulence excites a small-scale dynamo process that transports and amplifies the fields originated from the radio jet/lobe system. This process could be the primary process of populating the whole cluster with magnetic fields. We describe the properties of magnetic fields, including their strength, spatial distribution, power spectra and saturation mechanism. These simulations can be compared with observations made by VLA, LOFAR, and E-VLA.
  • February 9, 2011 | 3:30 PM | RI 480
    Joys of turbulent convection and dynamos in both stellar envelopes and cores
    Juri Toomre, JILA, University of Colorado at Boulder

    Stellar convection zones in most settings should be able to build magnetic fields through dynamo action, especially if the flows are turbulent and the stars rotate. There is much more subtlety as to whether the resulting magnetic fields also exhibit large-scale structure and possible temporal flips and even cycles. We have been studying through 3-D global simulations the nature of both differential rotation and dynamo action that can be achieved in G-type stars like the sun by turbulent convection in their outer envelopes, and also by core convection in more massive A-type stars. The richness of structures realized will be discussed.
  • February 23, 2011 | 3:30 PM | RI 480
    The physics of magnetohydrodynamics turbulence
    Stanislav Boldyrev, University of Wisconsin - Madison

    The talk will discuss what is currently known about the properties of incompressible magnetohydrodynamic (MHD) turbulence. The talk will start with a general introduction, and then will review recent analytic developments, numerical simulations, and where possible, observations and experiments. The discussion will include the role of the guide field and the ideal conservation laws, the inherent anisotropies of the turbulent energy cascade, the physics of the "imbalance" or the Alfvenization phenomenon, and the processes of self-organization.
  • March 2, 2011 | 3:30 PM | RI 480
    Blast from the Past: Hydrodynamic and X-ray Modeling of the Circumstellar Medium as Clues to Supernova Progenitors
    Vikram Dwarkadas, University of Chicago

    Supernovae (SNe) are divided into many types and sub-types,but the precise progenitor of each (sub)type of SN still remains unknown. Core-collapse supernovae (SNe) arise from the explosion of massive stars. The resultant shock wave expands in the circumstellar medium formed by mass-loss from the massive star. The interaction of the shock wave with this medium gives rise to X-ray and radio emission. In this talk we will discuss how circumstellar interaction can be used to constrain the SN progenitor. As a specific example, we will consider SN1996cr, one of the five closest SNe to explode in the past 30 years, yet which lay undiscovered for many years. Our team was awarded a 500,000 sec Chandra HETG observation of the SN, which was completed in early 2009. In order to interpret this data, we have carried out hydrodynamic simulations, followed by computations of simulated X-ray spectra under non-equilibrium ionization conditions, that can be directly compared with the observations. These calculations allow us to infer the evolution of the SN shock wave, the density structure, and the abundances of the ejecta and surrounding medium, to reasonable accuracy. We will show how the data allow us to constrain the progenitor properties. The deep spectra even allow us to investigate the 3D morphology of this point source by studying the detailed line shapes. We will discuss the implications for massive star mass-loss and SN evolution.


  • January 3, 2011 | 1:30 PM | LASR-E Conference Room
    Origins of Stars and Planets: 2020 Vision(s)
    Michael Meyer, Institute for Astronomy, ETH, Zurich

    Despite recent setbacks, the next decade should still see the realization of two revolutionary capabilities in astrophysics: the launch of the James Webb Space Telescope and (hopefully) first light for at least one Extremely Large Telescope (such as the GMT or the E-ELT). Both of these will make fundamental contributions towards understanding the origins of stars (like our Sun) and planetary systems (like our own), and thus our place in the Universe. I will compare and contrast these facilities from the perspective of star and planet formation, with a focus on the direct detection of extra-solar planets as a critical test for theories of planet formation and evolution (based on extrapolation from current work).
  • January 27, 2011 | 3:00 PM | RI 480
    The Small Star Opportunity to Find and Characterize Habitable Planets
    Jacob Bean, Harvard University

    One of the most exciting aspects of the field of exoplanets is the push towards the detailed study of habitable planets. Although most attention in this area is focused on Sun-like stars and has a time-horizon of decades, low-mass stars offer a real opportunity for the detection and atmospheric characterization of such planets in the near-future. I will describe work to overcome the technical challenges to making these kinds of observations for planetary systems around low-mass stars. I will also present results from two studies that utilize the power of low-mass stars: a planet search sensitive to potentially habitable planets and the first atmospheric characterization of a "super-earth" type planet. I will conclude with a look ahead at how similar observations with future instruments could yield the detection of biologically relevant molecules in the atmosphere of a potentially habitable planet around a low-mass star by the end of the decade.
  • February 3, 2011 | 3:00 PM | Room 101, Hinds
    Characterizing Super-Earths
    Diana Valencia, Observatoire de la Cote d'Azur

    Within the rapidly evolving field of exoplanets, super-Earths stand out as exceptional objects. They do not exist in our solar system, but they bear a relation to the terrestrial planets and icy satellites and thus constitute a new laboratory to test ideas. Remarkably, a subset of them may be habitable, making them interesting planets to characterize. In addition, the recent detections of the first three transiting low-mass planets mark the beginning of a prosperous field. The first generation of data arriving now is masses and radii, and in this context I will present results, challenges and future venues for inferring the composition and early evolution of these planets. Looking into the future, within the next decade we expect to have measurements of a coarse spectrum, which may provide a window into the understanding of the dynamics of the interior and thermal evolution of these potentially habitable planets.
  • February 10, 2011 | 3:00 PM | RI 480
    Seeing Other Solar Systems in the Making: Direct Imaging and Spectroscopy of Planets and Planet-Forming Disks
    Thayne Currie, NASA-Goddard Space Flight Center

    In this talk, I will describe new results on direct imaging and spectroscopy of young planets and planet-forming disks around other stars that provide a context for the evolution of the solar system's planets. First, I will discuss why direct imaging is both essential for characterizing planets around other stars and will explain the observing and image processing techniques that have proven successful for direct imaging. Second, I will present new science results from directly imaging gas giant planets around nearby, young stars, in particular the multi-planet system HR 8799. My data reveal a newly-detected, 4th planet orbiting at ~15 AU; my analysis shows that the HR 8799 planets have unique atmospheric properties, specifically thicker/denser clouds not found in other substellar objects and not predicted from standard atmosphere models. I will also present new detections of other young planets and images of planet-forming disks showing strong evidence for hitherto unseen planets. Starting next year, the Gemini Planet Imager instrument, with which I'm involved, will spatially resolve numerous planet-forming disks, provide a sensitive probe of the atmospheric evolution of over 100 soon-to-be imaged massive gas giants, and require facilities like Magellan for follow up. Finally, by the end of this decade, the University of Chicago-supported Giant Magellan Telescope will image and probe the atmospheric evolution of even lower-mass planets, potentially including young Earths.
  • February 17, 2011 | 3:00 PM | RI 480
    Observing Planet Formation in Nearby Circumstellar Disks
    Lucas Cieza, Institute of Astronomy, University of Hawaii

    Circumstellar disks are an integral part of the star formation process and the sites where planets are formed. Understanding their evolution is crucial for planet formation theory. Disks evolve through various physical processes, including accretion onto the star, grain growth and dust settling, dynamical interactions, and photoevaporation. In this talk, I will review our current understanding of the evolution of protoplanetary disks and the constraints they provide on planet formation processes. I will present results from our work on the so-called "transition" circumstellar disks, aiming to identify the sites of ongoing giant planet formation (i.e., the ultimate planet formation laboratories!). I will also discuss the prospects for detailed studies of these fascinating objects with the Atacama Large Millimeter Array (ALMA) as well as for the direct detection of forming planets with current and future instrumentation.
  • February 24, 2011 | 3:00 PM | RI 480
    Planetary Systems from Kepler
    Dan Fabrycky, UCO/Lick Observatory

    On Feb. 2, the Kepler space mission released its first 4 months of data on all targets, as well as a series of papers on statistical results on transiting exoplanets. Perhaps the biggest surprise is the great abundance of candidate multiple-planet systems; out of 997 targets with a candidate transiting exoplanet, 170 of them hosted multiple candidates. I describe the dynamics (stability, transit timing variations) and architecture (resonances, inclinations) of these new planetary systems. Dynamics allows us to confirm that some of these systems are indeed planetary (Kepler-9, Kepler-11), and continued monitoring of these and other systems (the ultra-compact KOI-500, the coorbital KOI-730) will challenge and refine theories of the formation of planetary systems.
  • February 25, 2011 | 3:00 PM | RI 180
    Characterizing Magnetized Turbulence in Molecular Clouds and Galaxies
    Martin Houde, University of Western Ontario

    While Submillimetre polarimetry of dust emission is arguably the most common observational tool to probe magnetic fields in molecular clouds, it has mainly been used to provide a measure of their geometry and their strength through the so-called Chandrasekhar-Fermi technique. The usefulness and accuracy of this technique are however hampered by observational biases, such as the signal integration along the line of sight and across the telescope beam. I will show how it is possible to account and correct for this effect, and significantly improve results obtained with the Chandrasekhar-Fermi equation. I will also discuss how an extension of this analysis can lead to a complete characterization of the magnetized turbulence power spectrum in molecular clouds and Galaxies (using polarization of synchrotron emission). I will present examples showing measurements of the turbulent energy dissipation scale due to ambipolar diffusion,and of the anisotropy of the magnetized turbulent power spectrum