University of Toronto Astronomy Colloquia



	ASTRONOMY COLLOQUIA

Spring 2010

Jan 22	Prof. Greg Laughlin (UC Santa Cruz) *Major Updates to the Galactic Planetary Census* The past year has seen enormous advances in our understanding of extrasolar planets. In this talk, I'll focus on some of the most exciting recent highlights. These include (i) the discovery and characterization of remarkable new transiting planets, (ii) a complete upending of the conventional wisdom regarding the statistics of the galactic planetary census, and (iii) a new method for actually looking inside certain transiting planets.
Jan 29 Cody Hall	Dr. Jonathan Sievers (CITA) *Recent Results from the Atacama Cosmology Telescope* The Atacama Cosmology Telescope (ACT) is a 6-metre diameter telescope observing at millimeter wavelengths from the Chilean Andes. We have recently released a measurement of the CMB power spectrum to an ell of 8000. I will present these results and discuss them in the context of recent South Pole Telescope and WMAP 7-year results, with particular attention on an evolving understanding of the Sunyaev-Zeldovich effect from galaxy clusters.
Feb 05	Ivan Semeniuk (DI) *News of the Universe: The Art, Science & Business of Astronomical Reporting in a Changing Media Landscape* Over the past 15 years, the evolution of online media has created unprecedented public access to astronomy news in a multitude of styles and formats. Yet, it has also completely overturned the business models that formerly supported astronomy-oriented journalists in various traditional media. This talk offers a snapshot of the forces at work on the profession and considers how news of astronomical discoveries and research will be communicated to the public (and by whom) in the future.
Feb 12 Cody Hall	Prof. Jerry Sellwood (Rutgers University) *New Developments in Spiral Structure Theory* Over 150 years after their discovery, astronomers still lack a complete theory for the origin of the beautiful spiral patterns in disk galaxies. I will review the various ideas that have been proposed and describe some recent observational data that appear to support a recurrent instability mechanism.
Feb 26 Cody Hall	Prof. Pawel Artymowicz (U of T) *Migrations: bodies in disks, computing platforms...*
Mar 05	Prof. Duncan Brown (Syracuse University) *Gravitational-Wave Astronomy with LIGO* The Laser Interferometer Gravitational Wave Observatory (LIGO) and its international partners Virgo and GEO are currently searching for gravitational-waves from astrophysical sources. The Initial LIGO detectors completed a two-year observing run in 2005-2007 at design sensitivity and the Enhanced LIGO detectors are presently searching for the first gravitational-wave signals to be seen. The Advanced LIGO detectors, currently under construction, will increase the volume of the Universe surveyed by a thousandfold or more. One of the remarkable aspects of the search for gravitational waves is that detection of these waves will bring new knowledge of both fundamental physics and astrophysics. To exploit this potential, it is vital that gravitational-wave astrophysicists work closely with the source modeling and astronomical communities. In this talk, I will review the status of the search for gravitational waves with LIGO. I will also describe how information from numerical modeling of binary black holes is being used to improve current and future gravitational-wave searches.
Mar 12	Dr. Mariska Kriek (Princeton) *A Deep View on the Early Universe: Extreme Makeovers & Overweight Galaxies* Recent studies have demonstrated that the galaxy population at z=2-3 shares characteristics with today's galaxies: massive galaxies are predominantly red, a color-density relation was already in place, and massive quiescent galaxies form a red sequence in color-mass space. However, the high-redshift universe far from resembles the local universe. Massive galaxies at z~2.5 do not seem to represent a Hubble sequence as their structures and morphologies are different from their local analogs. Furthermore, the space density of massive galaxies still has to grow significantly, implying that many local early-type galaxies assemble or form at later times. In my talk I will discuss these similarities and differences, and their implications for our understanding of the physical processes that govern galaxy formation and evolution.
Mar 19 Cody Hall	Prof. Alex Wolszczan (Penn State University - Center for Exoplanets and Habitable Worlds) *Planets around evolved stars* Discoveries of planets around Sun-like stars have taught us much about the nature of extrasolar planetary systems. However, issues such as planet formation around higher mass stars and long-term evolution of planetary systems have been left out from the mainstream exoplanet research, because the radial velocity method of planet detection becomes inefficient for spectral types earlier than F6-F8. An attractive way to remove this deficiency is to search for planets around giant stars, which have cool atmospheres and their spectra are rich in absorption lines that can be used for planet detection. In addition, planets have been discovered around neutron stars, a post-red-giant star and, possibly, around at least one white dwarf, all of which demonstrates the spectacular robustness of the planet formation process. In this talk, I will review the development of this relatively new field in the exoplanet research and present the Penn State - Torun Centre for Astronomy search for planets around GK-giants and other stars with the 9.2-m Hobby-Eberly Telescope.
Mar 26	Dr. Linda Smith (STScI) *The Starburst Galaxy M82* The M81 group of galaxies provides an excellent laboratory for studying galaxy-galaxy interactions and the ensuing violent episodes of star formation. The starburst galaxy M82 is believed to have suffered a close encounter with M81 some 250 Myr ago which triggered the current nuclear starburst. I will present HST imaging and Gemini-North spectroscopy of massive star clusters distributed across the disk and central regions of M82. These data represent the largest spectroscopic dataset to date for extragalactic young clusters. I will discuss the cluster formation history of M82 and the last interaction with M81. I will also present Gemini-North Integral Field Unit spectroscopy of the galactic-scale wind and discuss what these data reveal about the complex multi-phase wind of M82.
Apr 09	Prof. Chuck Steidel (Caltech) *Exploration of the Circum-Galactic Medium at High Redshifts* During the peak epoch of galaxy formation, the intergalactic medium is both the source of gas fueling star formation in forming galaxies, as well as the waste dump for the products of star formation and black hole accretion that are not retained by galaxies. y studying the "Circum-Galactic Medium", the region within a few hundred physical kpc of forming galaxies, one can begin to constrain the flow of baryons into and out of galaxies. At present, there is a puzzling discrepancy between observations and theoretical expectations whose resolution may be the key to unraveling the aspects of galaxy formation that are least well-understood.
Apr 16	Dr. Pawel Pietrukowicz (Nicolaus Copernicus Astronomical Center) *Galactic Bulge in 3D. The VVV project.* The VVV survey (VISTA Variables in the Via Lactea) is one of six ESO Public Surveys on the new 4.0-meter VISTA telescope. It will target the Galactic bulge and a piece of the adjacent plane in near-IR to detect a large number of variable objects. These will be used to create a 3-D map of the bulge from well-understood distance indicators such as RR Lyrae stars. Other science drivers include the ages of stellar populations, globular cluster evolution, as well as the stellar initial mass function.
Apr 23	Dr. Jim Hesser (DAO - HIA) *Beyond The International Year Of Astronomy 2009* Thanks to thousands of people, mostly volunteers, from diverse elements of society, IYA2009 was an extraordinary global education and public outreach success. The momentum generated now nourishes efforts to achieve IYA's desired legacies in improved education and public understanding of astronomy and its societal benefits. In Canada we substantially strengthened our partnerships between professional and amateur astronomers, while forming many new partnerships and linkages reaching beyond our traditional partners. This presentation strives to provide an overview of IYA2009 globally and nationally, as well as of Canadian opportunities being pursued during Beyond IYA, and raises issues of interest to those who care about the future of Canadian astronomy.
Apr 30 11AM Cody Hall	Dr. Andrej Prsa (Villanova University) *Artificial intelligence approaches to modeling eclipsing binary stars* Eclipsing binary stars are among the most important celestial objects in astrophysics because they provide a unique way to unbiasly determine absolute parameters of stars (their masses, radii,temperatures) in the universe. Since eclipsing binaries can host any type of stars, be it main sequence, instability strip, giants or dwarfs, pulsars or black holes, they are essential astrophysical laboratories for our stellar studies. Eclipsing binaries are also extremely important for measuring distances in the universe and calibrating other standard candles. Obtaining geometrical and physical parameters of eclipsing binaries involves solving the inverse problem: finding a set of parameters that produce synthetic data curves that best match observations. A promised scientific yield gave rise to early computer programs, such as the well-known Wilson-Devinney code, that have been gaining on accuracy and complexity over the past 4 decades. Yet a dawn of a new era is upon us, where robotic telescopes and dedicated surveys are acquiring massive amounts of data and tools devised for manual reduction and analysis are no longer adequate. New approaches that are able to handle hundreds of thousands of data curves in a fully automatic way are thus needed. The EBAI project (Eclipsing Binaries with Artificial Intelligence) explores one such approach - the use of back-propagating neural networks to determine principal parameters of eclipsing binaries. I will present the scheme, benchmarks and the results of the EBAI approach.

Last modified: 07 Sep 2011, 10:42:27

Marten van Kerkwijk (mhvk@astro)

Colloquia are Fridays, at 2 PM, in Cody Hall. They are followed by refreshments in the lounge, AB 201.

Instructions for speakers

Schedule with abstracts

Schedule without abstracts

Student seminars

Physics colloquia

Past colloquia: 2003A, 2003B, 2004A, 2004B, 2005A, 2005B, 2006A, 2006B, 2007A, 2007B, 2008A, 2008B, 2009A, 2009B, 2010A, 2010B, 2011A

Current colloquia: 2011B