Astronomy Colloquia

The Young and the Restless Stars

Speaker: 
Lynne Hillenbrand
Event Date and Time: 
Mon, 2015-03-30 15:30 - 16:30
Location: 
Hennings 318

Young stars associated with regions of recent and ongoing star formation are amenable to study across almost the entire electromagnetic spectrum.  Furthermore, they are enigmatically variable over much of this range -- due to processes occurring in the inner circumstellar disk, the disk-to-star accretion zone, and perhaps the outflow regions.  The talk will give an overview of the relevant phenomena and present several types of state-of-the-art multiwavelength time domain data sets along with their physical interpretation.

A calibration of the stellar-mass fundamental plane at <z> = 0.5 using the micro-lensing induced flux ratio anomalies of macro-lensed quasars

Speaker: 
Paul Schechter (MIT)
Event Date and Time: 
Mon, 2015-03-23 15:30 - 16:30
Location: 
Hennings 318
We measure the stellar mass surface densities of early type galaxies
by observing the micro-lensing of macro-lensed quasars caused by
individual stars, including stellar remnants, brown dwarfs and red
dwarfs too faint to produce photometric or spectroscopic signatures.
Instead of observing multiple micro-lensing events in a single system,
we combine single epoch X-ray snapshots of ten quadruple systems, and
compare the measured relative magnifications for the images with those
computed from macro-models.

Circumstellar disks and planet formation with ALMA

Speaker: 
Meredith Hughes (Wesleyan)
Event Date and Time: 
Mon, 2015-03-16 15:30 - 16:30
Location: 
Hennings 318

Circumstellar disks provide the raw material and initial conditions for planet formation.  Millimeter-wavelength interferometry is a powerful tool for studying gas and dust in planet-forming regions, and it is undergoing an immense leap in sophistication with the advent of the ALMA interferometer.  I will discuss some ways in which we are using millimeter-wavelength interferometry to study the process of planet formation in circumstellar disks, with particular emphasis on the kinematics of turbulence in protoplanet

Alternative Lifestyles in Old Open Star Clusters: At the Interface of Stellar Evolution and Stellar Dynamics

Speaker: 
Robert Mathieu (U Wisc-Madison)
Event Date and Time: 
Mon, 2015-02-23 15:30 - 16:30
Location: 
Hennings 318

Nearly one quarter of all stars in old open star clusters do not follow classical single-star evolution paths. These non-standard evolutionary paths are closely associated with the large binary-star populations in these clusters.

Meteoritic and Planetary Constraints on Our Protoplanetary Disk

Speaker: 
Steve Desch (ASU)
Event Date and Time: 
Mon, 2015-02-02 15:30 - 16:30
Location: 
Hennings 318

Planets form from protoplanetary disks, and our own solar nebula was one example. To understand how planets form, we must first constrain the surface density of gas and dust in such disks, and how the surface density evolves over time.

The Origin of Stellar Masses

Speaker: 
Mark Krumholz (UCSC)
Event Date and Time: 
Mon, 2015-01-26 15:30 - 16:30
Location: 
Hennings 318

The mass distribution of newborn stars, known as the initial mass function (IMF), has a distinct peak at a mass slightly less than that of the Sun. This characteristic stellar mass appears to be nearly invariant across a huge range of star-forming environments, and over most of cosmic time. Explaining its origin and universality is one of the oldest problems in theoretical astrophysics, and a fully successful theory eludes us even today. In this talk, however, I describe recent progress toward an explanation for the mass scale of stars.

The HTRU All-Sky Radio Pulsar Survey

Speaker: 
Cherry Ng (UBC)
Event Date and Time: 
Mon, 2015-03-09 15:30 - 16:30
Location: 
Hennings 318

The extreme conditions found in and around pulsars make them fantastic natural laboratories, providing insights to a rich variety of aspects of fundamental physics and astronomy. To discover more pulsars we have begun the High Time Resolution Universe (HTRU) survey. The HTRU-South low-latitude survey employs the 64-m Parkes radio telescope in Australia and this project promises to provide the deepest large-scale search ever for the Galactic plane region.

Probing small exoplanets from above and below (Earth's atmosphere)

Speaker: 
Diana Dragomir (UCSB)
Event Date and Time: 
Mon, 2015-01-12 15:30 - 16:30
Location: 
Hennings 318

The number of known transiting planets has increased by a factor of a few in the years since Kepler was launched, mainly thanks to the abundant harvest delivered by the mission itself. Statistical analyses of these and the significantly more numerous Kepler planet candidates indicate that smaller planets are more common than large ones. Super-Earths and mini-Neptunes (planets with radii between 1 and 4 R_Earth) are of particular interest because they constitute a class of objects which are not represented in our Solar System.

The Cosmic Microwave Background and the future of Observational Cosmology

Speaker: 
Graeme Addison
Event Date and Time: 
Mon, 2014-11-10 15:30 - 16:30
Location: 
Hennings 318

In the decades following the detection of fluctuations in the cosmic microwave background (CMB) an enormous observational effort has been made to measure and characterize these fluctuations in ever-increasing detail. Why is the CMB such a powerful cosmological probe? Why are we still building new instruments to study it? What new physics is it going to tell us?

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.

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