Astronomy Colloquia

A Tour of the Atacama Cosmology Telescope

Speaker: 
Adam Hincks (UBC)
Event Date and Time: 
Mon, 2014-09-29 15:30 - 16:30
Location: 
Hennings 318

The Atacama Cosmology Telescope (ACT) is an instrument dedicated to producing polarised maps of the cosmic microwave background (CMB). With a six-metre primary mirror, it has significantly higher resolution than most other CMB survey instruments, making it more sensitive to important small-scale features in the CMB, such as distortions from gravitational lensing, the imprint of galaxy clusters by the Sunyaev-Zeldovich effect and emission from dusty, star-forming galaxies.

Mercury’s Magnetic Field

Speaker: 
Catherine Johnson (UBC)
Event Date and Time: 
Mon, 2014-11-24 15:30 - 16:30
Location: 
Hennings 318
Mercury is the only inner solar system body other than Earth to possess an active core dynamo-driven magnetic field, and the only planet with a highly dynamic, small magnetosphere. Measurements made by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft have provided a wealth of data on Mercury’s magnetic field environment.

A mass map of the Universe with CMB lensing

Speaker: 
Duncan Hanson
Event Date and Time: 
Mon, 2014-12-08 15:30 - 16:30
Location: 
Hennings 318

The anisotropies of the Cosmic Microwave Background subtly distorted by gravitational lensing. This is both a nuisance, and a unique source of information about the distribution of mass in our Universe. I will present the most powerful measurement of this lensing effect to date, using temperature and polarization data from the Planck 2014 data release last week.

Tracing mass accretion in star forming filaments

Speaker: 
Rachel Friesen (Dunlap Institute)
Event Date and Time: 
Mon, 2014-12-01 15:30 - 16:30
Location: 
Hennings 318

Most stars in our galaxy do not form in isolation. Instead, stars are
born in groups and clusters embedded within dense filaments and clumps
in molecular clouds. Many clustered star-forming regions share similar
morphologies, where the greatest star formation rates are found within a
central ‘hub’ of dense molecular gas, that is connected to streams or
filaments of additional material. To understand how stars form in
clusters, we need to understand how these filaments accrete mass from

Rethinking Galactic Architecture: Clues from Satellites and Destroyed Dwarfs

Speaker: 
Alis Deason (UCSC, Hubble Fellow)
Event Date and Time: 
Mon, 2014-11-17 15:30 - 16:30
Location: 
Hennings 318
The cannibalistic nature of the Milky Way galaxy leads to the continuous capture and destruction of lower-mass, dwarf galaxies. The remains of destroyed dwarfs are splayed out in a diffuse stellar halo, while the "survivors" comprise the satellite population that orbits the Milky Way. These halo populations provide a unique opportunity to decipher the accretion history of the Milky Way with a level of detail that cannot be achieved in any other galaxy. I will discuss current and future projects aiming to decipher the nature of the halo's building blocks.

X-rays from Rapidly Rotating Neutron Stars as a Diagnostic of their Interiors

Speaker: 
Sharon Morsink (University of Alberta)
Event Date and Time: 
Mon, 2014-11-03 15:30 - 16:30
Location: 
Hennings 318
Neutron stars are tiny stars with ultra-strong magnetic and gravitational fields and densities larger than nuclear. Their small size and large  average densities allow them to spin at very rapid rates, with surface velocities that are a large fraction of the speed of light. X-rays emitted by rapidly rotating neutron stars accreting matter from a companion can be used to constrain the unknown properties of supra-nuclear density matter  found in their cores.

The Sad Story of the Cosmic EUV Background

Speaker: 
Matt McQuinn (University of Washington)
Event Date and Time: 
Mon, 2014-10-27 15:30 - 16:30
Location: 
Hennings 318

After reionization, a largely uniform ~1 Rydberg background pervaded the
Universe, keeping the intergalactic hydrogen extremely ionized. The
characteristics of this background depend on the properties of the sources
(quasars and galaxies) and the absorbers (Lyman-limit systems). Modeling the
sources is difficult, but I will argue that the absorbers seem to be
captured in cosmological simulations, at least at high redshifts. Quick
evolution (on a time < 0.1 H(z)^-1) in the ionizing background is observed

Cometary Impact Rates at Jupiter and Beyond

Speaker: 
Luke Dones (SwRI)
Event Date and Time: 
Mon, 2014-10-20 15:30 - 16:30
Location: 
Hennings 318

Most impact craters on the Moon and terrestrial planets are created by
asteroids - bodies whose orbits lie within Jupiter's orbit. Impacts on
the giant planets and their satellites, by contrast, are thought to be
dominated by "comets" - bodies from the Kuiper Belt/Scattered Disk
beyond Neptune. Cometary impact rates are uncertain because small
bodies in the Kuiper Belt are still invisible to us, and because
comets - unruly by nature - sometimes break up for reasons of their

3D model atmospheres of white dwarfs

Speaker: 
Pier-Emmanuel Tremblay (Hubble Fellow, Space Telescope Science Institute, Baltimore)
Event Date and Time: 
Mon, 2014-10-06 15:30 - 16:30
Location: 
Hennings 318

Most stars become white dwarfs at the end of the stellar life cycle.
The study of these old degenerate remnants in clusters and the
galactic halo provides essential information about the first stellar
populations in our galaxy. We have recently computed the first grid
of 3D model atmospheres for hydrogen-atmosphere white dwarfs.
These time-resolved radiation-hydrodynamics simulations, unlike the
commonly used 1D calculations, do not rely on the mixing-length theory

Mapping the Deep: First Discoveries from the Outer Solar System Origins Survey

Speaker: 
Michele Bannister
Event Date and Time: 
Mon, 2014-09-22 15:30 - 16:30
Location: 
Hennings 318

The exploration of the outer Solar System has reached an exciting point: we are now beginning to understand its dynamical structure, sculpted into existence by giant planet migration in the early history of the Solar System. We have designed a survey using 560 hours of CFHT time over four years to provide hundreds of new trans-Neptunian objects with exquisitely characterised, high-precision orbits.

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