Astronomy Colloquia

Asteroseismology: A new Keplerian revolution

Speaker: 
Professor Donald Kurtz (Jeremiah Horrocks Institute, University of Central Lancashire)
Event Date and Time: 
Thu, 2017-08-10 12:30 - 13:45
Location: 
Hennings 318
Local Contact: 
Jaymie Matthews
Intended Audience: 
Graduate
In 1926 in the opening paragraph of his now-classic book, The Internal Constitution of the Stars, Sir Arthur Eddington lamented, “What appliance can pierce through the outer layers of a star and test the conditions within?” While he considered theory to be the proper answer to that question, there is now an observational answer: asteroseismology. We are in a time of a significant advance in our understanding of stellar astrophysics with data from the Kepler Mission. From its rich 4-year data set nearly 5000 exoplanet candidates have been discovered - the majority of all known.

Corralling a distant unseen planet with extreme resonant Kuiper Belt Objects

Speaker: 
Renu Malhotra (Lunar and Planetary Lab, University of Arizona)
Event Date and Time: 
Mon, 2017-04-24 15:30 - 16:45
Location: 
Hennings 318
Local Contact: 
Brett Gladman and Jaymie Matthews
Intended Audience: 
Graduate
Several recent studies have appealed to the clustering of the angular orbital elements of very distant, extreme Kuiper Belt Objects (eKBOs) to argue for the existence of a large planet in the distant Solar System. I will review these arguments, and also describe other properties of eKBOs that may support the existence of such an unseen planet. We observe that several eKBOs have orbital periods close to integer ratios with each other. These are not dynamically significant unless the eKBOs are in mean motion resonances (MMRs) with a massive planet.

Scaling laws for dark matter halos of late-type and dwarf spheroidal galaxies

Speaker: 
John Kormendy (University of Texas at Austin)
Event Date and Time: 
Thu, 2017-03-23 12:30 - 13:45
Location: 
Hennings 301 - NOTE DIFFERENT LOCATION
Local Contact: 
Jaymie Matthews and Philip Stamp
Intended Audience: 
Graduate
Dark matter (DM) halos of Sc-Im and dwarf spheroidal (dSph) galaxies satisfy scaling laws: halos in lower-luminosity galaxies have smaller core radii, higher central densities, and smaller velocity dispersions. These results are based on maximum-disk rotation curve decompositions for giant galaxies and Jeans equation analysis for dwarfs. (1) We show that spiral, Im, and Sph galaxies with absolute magnitudes M_V > -18 form a sequence of decreasing baryon-to-DM surface density with decreasing luminosity.

High redshift starburst galaxies revealed by the South Pole Telescope, ALMA, and gravitational lensing

Speaker: 
Scott Chapman (Dalhousie University)
Event Date and Time: 
Mon, 2017-02-27 15:30 - 16:45
Location: 
Hennings 318
Local Contact: 
Jaymie Matthews
Intended Audience: 
Graduate
Recent facilities such as the South Pole Telescope (SPT), the Herschel Space Observatory, and the Atacama Large Millimeter Array (ALMA) have opened a window to the millimeter (mm) sky and revealed a unique and unprecedented view of the Universe. In a 2500-square-degree cosmological survey, SPT has systematically identified a large number (200) of high-redshift strongly gravitationally lensed starburst galaxies.

Early modern multiverses from Digges to Milton

Speaker: 
Dennis Danielson (UBC Department of English)
Event Date and Time: 
Mon, 2017-01-30 15:30 - 16:45
Location: 
Hennings 318
Local Contact: 
Jaymie Matthews
Intended Audience: 
Undergraduate
Defying possible charges of anachronism, I will propose that the term "multiverse" – applied to the period from Copernicus to Newton – permits us to discern more clearly how cosmological thinkers occasionally embedded (rather than merely displacing or replacing) older models of our universe within newer versions of the whole shebang. It also saves us from the incoherence of applying "universe" to multiple entities of different scales, and of calling something that is perhaps mainly chaotic a "cosmos."

Radio cosmology in South Africa

Speaker: 
Yin-Zhe Ma ( University of KwaZulu-Natal)
Event Date and Time: 
Mon, 2017-01-23 15:30 - 16:45
Location: 
Hennings 318
Local Contact: 
Douglas Scott and Jaymie Matthews
Intended Audience: 
Graduate

My talk will be in two parts. PART 1: Mapping the integrated emission from redshifted neutral hydrogen is an emerging and completely independent way of optical surveys to measure Baryonic Acoustic Oscillations (BAOs) at low redshifts. The observations of the HI signal will be contaminated by instrumental noise, atmospheric noise and diffuse emissions coming from our Galaxy, which are expected to be at least four orders of magnitude brighter than the HI signal we wish to detect.

Stellar flares from Proxima Centauri and TRAPPIST-1 with MOST and Kepler

Speaker: 
James Davenport (Western Washington University)
Event Date and Time: 
Mon, 2017-03-27 15:30 - 16:45
Location: 
Hennings 318
Local Contact: 
Jaymie Matthews
Intended Audience: 
Graduate
The MOST and Kepler space telescopes have pioneered the detection of extrasolar planets using high precision brightness monitoring of stars. With data spanning months to years for each star, these light curves also provide the best census of stellar phenomena including cool starspots and explosive flares. I will present results from studies of flares on active stars observed with Kepler and MOST, including the recently discovered exoplanet host stars TRAPPIST-1 and Proxima Centauri.

The Outer Solar System

Speaker: 
Matthew Payne (Harvard-Smithsonian Center for Astrophysics)
Event Date and Time: 
Mon, 2017-04-03 15:30 - 16:45
Location: 
Hennings 318
Local Contact: 
Aaron Boley and Jaymie Matthews
Intended Audience: 
Graduate
I will discuss recent discoveries arising from our detailed search of the Pan-STARRS Outer Solar System survey data. These include the discovery of several hundred Kuiper-Belt and Scattered-Disk Objects, as well as Neptune Trojans and a possible population of Centaurs that appear to occupy a common plane. In addition I will discuss the heliocentric linking methodology that has facilitated these discoveries. I will go on to discuss issues related to the putative "Planet-9", a ~10 Earth-Mass planet hypothesized to lurk unseen in a distant orbit at the edge of the Solar System.

Galaxy Fertility: Nature vs. Nurture

Speaker: 
Gary Mamon (Institut d'Astrophysique de Paris)
Event Date and Time: 
Thu, 2017-01-12 12:30 - 14:00
Location: 
Hennings 301 - NOTE DIFFERENT ROOM
Local Contact: 
Ludo van Waerbeke and Jaymie Matthews
Galaxies grow by gas infall and mergers, but their growth is constrained by mechanisms that limit the supply of gas to the molecular clouds where stars are observed to form. These mechanisms can be internal feedback processes from supernova explosions and outflows from active galactic nuclei around the central supermassive black hole. But the environment of galaxies can also affect the rate of star formation in galaxies, through physical processes such as tidal stripping and ram pressure stripping that starve the galaxy from its gas supply, as well as galaxy encounters.

Measuring the geometry of the Universe with Euclid

Speaker: 
Alina Kiessling (NASA Jet Propulsion Laboratory)
Event Date and Time: 
Mon, 2017-01-16 15:30 - 16:45
Location: 
Hennings 318
Local Contact: 
Jaymie Matthews
Intended Audience: 
Graduate
The Euclid mission is a European Space Agency (ESA) led space telescope with significant contributions from NASA (and now Canada!). Euclid will use two complementary probes to study the dark sector of the Universe. The concordance model of cosmology holds that 95% percent of the Universe is made up of dark matter and dark energy, yet we understand very little about these phenomena.
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