Poster: http://www.physics.uwo.ca/colloquia/Colloquia%20Notices/2011_2012/WRIGHT%20Colloquium.pdf

Western University
DEPARTMENT OF PHYSICS AND ASTRONOMY

PHYSICS & ASTRONOMY COLLOQUIUM

Date:          Thursday, 26^th April 2012
Time:          1:30 p.m.
Location:    Physics & Astronomy Seminar Room 22

Dr. Shelley Wright
Department of Astronomy & Astrophysics
and Dunlap Institute of Astronomy & Astrophysics
University of Toronto

“Studying Galaxies in the Early Universe with Innovative Astronomical Instrumentation”

ABSTRACT

Studies of galaxies in the early universe (z > 1) have greatly benefited from recent advances in diffraction-limited techniques on 8-10m telescopes using adaptive optics (AO) and integral field spectroscopy. These innovative spectrographs have led to significant scientific achievements and are stimulating the design of future instrumentation. My talk will focus on development and use of the latest near-infrared instruments behind Keck Observatory’s AO system. I will present OSIRIS and Keck AO observations of spatially resolved optical emission lines (e.g., Halpha, and [N II]) from high-redshift (1 < z < 3) star forming galaxies. These results are part of an ongoing survey to study the dynamics, chemical abundances, and active galactic nuclei (AGN) in early galaxies. The high spatial resolution and 2D capability of an integral field spectrograph has allowed the discovery of some of the lowest luminosity AGN known at this epoch, and I will discuss their potential impact on high-redshift metallicity studies and galaxy formation. Lastly, I will discuss future instrumentation upgrades for OSIRIS and development of new instrumentation on extremely large telescopes (30m), which will offer extraordinary potential to probe the dynamics, assembly, and abundances of galaxies in the early universe.

Coffee & cookies will be available, courtesy of PASA.

The University of Western Ontario
DEPARTMENT OF PHYSICS AND ASTRONOMY

Special Undergraduate LevelTalk

Date:          Tuesday, 17^th April 2012
Time:          10:30 a.m.
Location:    Physics & Astronomy Seminar Room 22

Dr. Nicolas Cowan
Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA)

Northwestern University, Illinois

“Tortured Climes: Infrared Observations of Hot Jupiters”

ABSTRACT

The discovery of gas giant planets in few-day orbits around their host stars posed serious challenges to theories of planet formation. In the last half-decade, our ability to probe the atmospheres of these hot Jupiters has likewise challenged our notions of climate. Many of these worlds have extremely eccentric orbits, leading to seasons that make Earth’s obliquity-driven seasons seem like a joke. For most Solar System planets, the dominant driver of heat transport is the equator-to-pole temperature gradient. On hot Jupiters, it is the huge day-night temperature contrast (from hundreds to thousands of degrees) that drives atmospheric circulation, potentially leading to transonic winds. Their atmospheres are slightly ionized, making magnetohydrodynamics relevant. Some of the shortest period gas giants have severely warped shapes due to tidal effects. In short, these planets are unlike anything climate scientists have thought much about.

I will present observational studies that can help constrain the mysterious workings of these planets. I will show how we can use time-resolved infrared photometry to learn about hot Jupiters.

Poster: http://www.physics.uwo.ca/colloquia/Colloquia%20Notices/2011_2012/METCHEV%20Research%20Talk.pdf

The University of Western Ontario
DEPARTMENT OF PHYSICS AND ASTRONOMY

PHYSICS & ASTRONOMY COLLOQUIUM

Date:          Monday, 23^rd April 2012
Time:          1:30 p.m.
Location:    Physics & Astronomy Seminar Room 22

Dr. Stanimir Metchev
Department of Physics and Astronomy

Stony Brook University, New York

“Exoplanetary Worlds: Atmospheres, Architectures, and Evolution”

ABSTRACT

The detection of global weather phenomena in irradiated extrasolar hot Jupiter planets has provided tremendous insights into their atmospheric structure. Non-irradiated substellar atmospheres probe weather in an entirely different regime, where global atmospheric flows result primarily from a combination of rapid rotation and internal convection—e.g., as in the atmosphere of Jupiter—rather than from external forcing. Isolated brown dwarfs are ideal targets for such investigations because they possess planet-like atmospheric dynamics, yet have greater intrinsic brightnesses and lack nearby bright stars to contaminate observations. I will overview recent results on non-irradiated brown dwarf and planetary atmospheres, and will present the prospects for the direct characterization of extrasolar planets with the coming generation of extreme-contrast imaging telescopes.

Poster: http://www.physics.uwo.ca/colloquia/Colloquia%20Notices/2011_2012/COWAN%20Research%20Talk.pdf

The University of Western Ontario
DEPARTMENT OF PHYSICS AND ASTRONOMY

PHYSICS & ASTRONOMY COLLOQUIUM

Date:           MONDAY, 16^th April 2012
Time:          1:30 p.m.
Location:    Physics & Astronomy Seminar Room 22

Dr. Nicolas Cowan
Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA)

Northwestern University, Illinois

“Divining the Climate of a Pale Blue Dot”

ABSTRACT

Temperate rocky planets are being discovered around nearby stars but we know precious little about them aside from mass, incident stellar flux, and sometimes bulk density. To understand what these worlds are like we will need to know their climate. This will most likely require one or more expensive space missions, and it is worth studying which measurement suites best constrain simple climate models. I will describe how the changing colour and brightness of an exoplanet—at both optical and thermal wavelengths—can be used to constrain its surface conditions and climate.

TODAY @ 1:30

JOINT SEMINAR—the Department of Physics and Astronomy and the Centre for Planetary Science and Exploration (CPSX)

Date:           Thursday, 5^th April 2012
Time:          1:30 p.m.
Location:    Physics & Astronomy Seminar Room 22

Dr. Nikku Madhusudhan
Yale Center for Astronomy and Astrophysics
Yale University

“Chemical Characterization of Exoplanetary Atmospheres”

ABSTRACT

Recent advances in exoplanetary science are leading to unprecedented constraints on chemical compositions of exoplanetary atmospheres. Molecular and elemental abundances derived from exoplanetary spectra provide critical clues on the chemical and dynamical processes in exoplanetary atmospheres, on the compositions of their interiors and formation environments, and on the potential habitability of rocky exoplanets. In this talk, I will present emerging constraints on chemical abundances for an ensemble of exoplanetary atmospheres, and their implications for atmospheric processes, interiors, and formation conditions of exoplanets. Strong constraints are emerging on mixing ratios of carbon and oxygen based molecules and on the elemental C/H, O/H, and C/O ratios in giant exoplanetary atmospheres. In particular, the C/O ratio critically influences the H₂O abundance, with major repercussions on atmospheric chemistry and thermal inversions, and on the compositions of ices and rocks in planetary interiors and protoplanetary formation zones. Some of the first constraints span C/O ratios of unity or higher, opening the exotic possibility of carbon-rich planets (CRPs). The properties and formation scenarios of CRPs will be discussed in this talk. Such compositional estimates of extrasolar planets open new research avenues at the intersections of geosciences, planetary science, and astronomy. I will discuss some frontier areas in this direction, along with an overview of observational campaigns, from ground and space, and theoretical and experimental efforts.

Coffee & cookies will be available, courtesy of PASA.

TODAY @ 2:00 p.m.

Department of Physics and Astronomy

MSc Public Lecture

Mykhaylo (Misha) Chavarha

Supervisor: Dr. Lyudmila Goncharova

“Defects and magnetism in SrTiO3 single crystals and ultra-thin films on Si”

DATE:      WEDNESDAY, 4^th April 2012

TIME:  1:30 p.m.2:00 p.m.

PLACE:   Physics & Astronomy Room 22

All are welcome to attend.

Department of Physics and Astronomy

MSc Public Lecture

Mykhaylo (Misha) Chavarha

Supervisor: Dr. Lyudmila Goncharova

“Defects and magnetism in SrTiO3 single crystals and ultra-thin films on Si”

DATE:      WEDNESDAY, 4^th April 2012

TIME:       1:30 p.m.

PLACE:   Physics & Astronomy Room 22

All are welcome to attend.

Poster: http://www.physics.uwo.ca/colloquia/Colloquia%20Notices/2011_2012/MADHUSUDHAN%20Joint%20Colloquium.pdf

JOINT SEMINAR—the Department of Physics and Astronomy and the Centre for Planetary Science and Exploration (CPSX)

Date:           Thursday, 5^th April 2012
Time:          1:30 p.m.
Location:    Physics & Astronomy Seminar Room 22

Dr. Nikku Madhusudhan
Yale Center for Astronomy and Astrophysics
Yale University

“Chemical Characterization of Exoplanetary Atmospheres”

ABSTRACT

Recent advances in exoplanetary science are leading to unprecedented constraints on chemical compositions of exoplanetary atmospheres. Molecular and elemental abundances derived from exoplanetary spectra provide critical clues on the chemical and dynamical processes in exoplanetary atmospheres, on the compositions of their interiors and formation environments, and on the potential habitability of rocky exoplanets. In this talk, I will present emerging constraints on chemical abundances for an ensemble of exoplanetary atmospheres, and their implications for atmospheric processes, interiors, and formation conditions of exoplanets. Strong constraints are emerging on mixing ratios of carbon and oxygen based molecules and on the elemental C/H, O/H, and C/O ratios in giant exoplanetary atmospheres. In particular, the C/O ratio critically influences the H₂O abundance, with major repercussions on atmospheric chemistry and thermal inversions, and on the compositions of ices and rocks in planetary interiors and protoplanetary formation zones. Some of the first constraints span C/O ratios of unity or higher, opening the exotic possibility of carbon-rich planets (CRPs). The properties and formation scenarios of CRPs will be discussed in this talk. Such compositional estimates of extrasolar planets open new research avenues at the intersections of geosciences, planetary science, and astronomy. I will discuss some frontier areas in this direction, along with an overview of observational campaigns, from ground and space, and theoretical and experimental efforts.

Coffee & cookies will be available, courtesy of PASA.

Department of Physics and Astronomy

ASTRONOMY SEMINAR

Dr. Hua-bai Li

Dr. Hua-bai Li

Max-Planck-Institut für Astronomie

Heidelberg, Germany

Confronting Star-formation Models with Magnetic-field Observations

ABSTRACT

Self-gravity, turbulence and magnetic fields (B-fields) certainly all play a role in the star-formation process, which transforms just a small fraction of the mass of molecular clouds into stars. How exactly these forces interact with each other to regulate star formation is, however, still highly controversial. I will report recent sub-mm/optical observations of B-fields, which can put constraints on the competing models of cloud formation, cloud fragmentation, cloud core formation, and ambipolar diffusion.

Date:          THURSDAY, 29^th March 2012

Time:          10:30 a.m.

Location:    Physics & Astronomy Room 22

Poster: http://www.physics.uwo.ca/colloquia/Colloquia%20Notices/2011_2012/CURIEL%20Colloquium.pdf

Western University
DEPARTMENT OF PHYSICS AND ASTRONOMY

PHYSICS & ASTRONOMY COLLOQUIUM

Date:          Thursday, 29^th March 2012
Time:          1:30 p.m.
Location:    Physics & Astronomy Seminar Room 22

Dr. Erik Curiel
Rotman Institute of Philosophy
Department of Philosophy
Western University

“Are Black Holes Hot or Cold?”

ABSTRACT

In the early 1970s it was realized that there is a striking formal analogy between the so-called laws of black-hole mechanics and the laws of classical thermodynamics. Before the discovery of Hawking radiation, however, it was generally thought that the analogy was only formal, and did not reflect a deep connection between gravitational and thermodynamical phenomena. In particular, it is still commonly held that the surface gravity of a stationary black hole can be construed as a true physical temperature only when quantum effects are taken into account; in the context of classical general relativity alone, one cannot cogently construe it so. Does the use of quantum field theory in curved spacetime offer the only hope for taking the analogy seriously? I think the answer is ‘no.’ To attempt to justify that answer, I shall begin by arguing that the standard argument to the contrary begs the question. Looking at the various ways that the idea of “temperature” enters classical thermodynamics then will suggest arguments that, I claim, show the analogy between classical black-hole mechanics and classical thermodynamics should be taken more seriously, at least so far as temperature goes, without the need to rely on or invoke quantum mechanics. If this is correct, then there may be a deep connection between classical general relativity and classical thermodynamics on their own, independent of quantum mechanics.

Coffee & cookies will be available, courtesy of PASA.