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Experts in: Fundamental aspects of astrophysics

BENNEKE, Björn

Professeur adjoint

The next five years present a truly unique opportunity in the history of planetary astrophysics. For the first time, the observational techniques, the theoretical models, and a sufficient number of known exoplanets orbiting nearby stars are available to spectroscopically characterize a wide diversity of planets. Planets ranging from blazingly hot giant planets to temperate Earth-sized planets in the habitable zone of their host stars.

Many unanswered questions remain: How and where do planets form? What materials make up their interiors? What gases are in their atmospheres? What role do clouds and hazes play? How big can a terrestrial planet be? How small can a gaseous planet be? And finally, what planets are capable of hosting life?

Professor Benneke’s team is currently in an exceptional position to address many of the questions above because they are currently conducting several unprecedented large observational programs using the Hubble Space Telescope, the Spitzer Space Telescope, and the 10-meter Keck observatories. They have developed powerful analysis and modeling framework to interpret these unique data sets. The main areas that Professor Benneke’s group is working on are:

  • Exploring the diversity of planetary atmospheres on super-Earths and exo-Neptunes using Hubble Space Telescope transit spectroscopy. Professor Benneke is the principal investigator of the largest Hubble Space Program in the world to characterize small exoplanets.
  • Probing the formation of giant planets using high-resolution near-infrared spectroscopy from 10-meter Keck telescopes
  • Atmospheric characterization and mapping of exoplanets using the upcoming James Webb Space Telescope (JWST)
  • Understanding the exotic cloud types on exoplanets
  • Discovery and initial characterization of prime targets for future JWST characterization using K2, TESS, and ground-based follow-up
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CHARBONNEAU, Paul

Professeur titulaire

The solar magnetic cycle is both the driver and energy source of all of solar eruptive phenomena with impacts on Earth, whether it has to do with space weather, damage to technological infrastructures or perhaps even impacts on Earth's long-term climate. The work of my research group aims in part at better understanding the physical mechanisms driving the solar magnetic cycle, including the significant fluctuations observed in the duration and amplitude of individual cycles. The unifying physical principle underlying all the phenomena that we model lies in the complex nonlinear interactions between the solar magnetic field and internal plasma flows in its outer layers.

We recently achieved a world first: a global magnetohydrodynamical convective dynamo simulation producing a large-scale magnetic field showing a very solar-like spatiotemporal evolution, including, in particular, regular polarity reversals taking place on a multi-decadal timescale. We are also developing novel computational approaches to modelling the photospheric impacts of the solar magnetic field, which allows us to couple solar-cycle models to reconstruction schemes for describing variations in spectral irradiance and solar luminosity during the activity cycle, a key step in better quantifying possible influences of solar activity on climate change.

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Hlavacek-Larrondo, Julie

HLAVACEK-LARRONDO, Julie

Professeure agrégée

I am an expert in the study of big black holes – those that lie at the centres of massive galaxies. I use a combination of X-ray (e.g. Chandra, XMM-Newton, Rosat), radio (e.g. JVLA, GMRT, ATCA) and optical observations (e.g. HST, VLT) for my work. The ultimate goal of my research is to provide a detailed view on the role black hole feedback plays in the formation and evolution of galaxies, from heating to metal entrainment, as well as black hole growth. Other topics I work on include observational signatures of radio halos in cluster mergers, hyper-luminours infrared galaxies, numerical simulations of jets, and compact objects in general.

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St-Louis, Nicole

ST-LOUIS, Nicole

Professeure titulaire

My research is mainly on the wind from the most massive stars. In view of their great luminosity - reaching one million times that of the Sun - these stars lose a large proportion of their mass over their lifetimes. This stellar wind is not symmetrical or homogenous. Not only does it contain small-scale inhomogeneities relating to turbulence, but in some cases also large-scale structures. These structures are particularly intriguing, since they are created by an as-yet unidentified mechanism occurring at the surface of the star.

The possible mechanisms include magnetic fields and pulses, two important physical processes in the evolution of massive stars, but about which we still have very little information.

The consequences of these large-scale structures for observable data (spectrum, photometry, polarization rate) can also help us to determine a fundamental parameter of these stars: their rotation velocity. This important detail is usually impossible to measure for the massive stars I am studying, since their surface is completely concealed behind the very dense wind. Because the large-scale structures are attached to the surface, identifying a period in the star's spectral or luminous variations lets us deduce the rotation velocity.

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