Past Colloquia
Direct imaging of extrasolar planets and the Gemini Planet Imager
Cody Hall
Bruce Macintosh (Stanford)
March 11, 2016
14:00 - 15:00
Abstract: While thousands of extrasolar planets and candidates have now been detected, but almost all through indirect methods such as transit photometry or radial velocity. Though statistically powerful, these techniques provide in most cases just a basic measurement of an object’s size and orbital parameters,…
Convection in Cool Stars, as Revealed through Stellar Brightness Variations
Cody Hall
Fabienne Bastien (Penn State)
March 04, 2016
14:00 - 15:00
Abstract: As a result of the high precision and cadence of surveys like MOST, CoRoT, and Kepler, we may now directly observe the very low-level light variations arising from stellar granulation in cool stars. Here, we discuss how this enables us to more accurately determine…
Ilse Cleeves (Harvard)
Cody Hall
Ilse Cleeves (Harvard)
February 26, 2016
14:00 - 15:00
details to follow
Clustering Redshifts: A New Era of Distance Measurement
Cody Hall
Mubdi Rahman, John Hopkins University
February 19, 2016
14:00 - 15:00
Measuring the true distance of objects seen on the celestial sphere is a challenge that has plagued astronomy from its earliest days. The classical solution to this problem for extragalactic systems has been measuring the regression velocity through spectroscopy to determine a redshift-related distance. However…
Toward a Holistic View of Star Formation
Cody Hall
Rob Gutermuth (UMASS Amherst)
February 12, 2016
14:00 - 15:00
Abstract: Our general picture of the process of forming stars from molecular clouds has held together quite well for the past few decades, but a detailed, predictive theory of star formation remains frustratingly out of reach. What determines the clustering of newborn stars? What sets…
An Astronomical Time Machine: Light Echoes from Historic Supernovae and Eruptions
Cody Hall
Armin Rest (Space Telescope Science Institute)
February 05, 2016
14:00 - 15:00
Tycho Brahe’s observations of a supernova (SN) in 1572 challenged the teachings of Aristotle that the celestial realm was unchanging. We have discovered a way to see the same light that Tycho saw 440 years ago by observing SN light that only now reaches Earth…
Stellar Magnetic Fields and Stellar Evolution
Cody Hall
Gregg Wade (RMC/Queens University)
January 29, 2016
14:00 - 15:00
All stars are natural magnets, thanks to the dynamic, electrically conductive gases that compose them. And because the magnetic fields of stars can be very strong, they represent a basic physical ingredient in the theory of stellar structure and evolution. In recently years it has…
Satellite galaxies and the baryon cycle
Cody Hall
Michael Balogh, University of Waterloo
January 22, 2016
14:00 - 15:00
Abstract: Late-time galaxy evolution is driven by a variety of non-linear processes such as radiative cooling, supernova feedback and AGN accretion, which together act to largely decouple baryonic structure growth from that of the dark matter. It remains a formidable challenge to untangle these processes…
Probing Gravity: Galaxies, CMB Lensing, and Intensity Mapping
Cody Hall
Anthony Pullen (Carnegie Mellon)
January 15, 2016
14:00 - 15:00
We discuss recent work exploring the use of large-scale structure to probe gravity. We first consider using CMB lensing and galaxy surveys to probe E_G, the ratio between curvature and velocity perturbations. This quantity is independent of galaxy clustering bias and is distinct for various…
Sean McGee (Birmingham)
Cody Hall
Sean McGee (University of Birmingham)
December 18, 2015
14:00 - 15:00
details to follow