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Experts in: Extrasolar planetary systems

Bastien, Pierre

BASTIEN, Pierre

Professeur associé

My research deals mostly with star and planetary system formation. This is one of the priority research areas identified by the Canadian astronomical community. For this research, I mainly use light polarization as a means of gathering data.

Here are two examples of my ongoing research projects:

  1. Natural light vibrates in a plane that varies continuously and at random. When it vibrates in a preferential plane, we say that it is polarized. For measuring polarization from celestial objects, I am supervising a new polarimeter being built for the Mont Mégantic Observatory, POMM, that will be 100 times more precise than the one currently in use. Light from a young star is scattered and polarized by microscopic dust grains. By measuring this polarization, we can learn more about the properties of the grains and the distribution of matter around young stars or with disks of debris. Combining these data with other observations and with modelling, we learn about conditions in protoplanetary disks where planets are formed. I will also be observing stars with exoplanets to learn about the properties of the atmospheres of these planets and determine the inclination of their orbits.
  2. I also built a polarimeter, POL-2, for the James-Clerk-Maxwell radiotelescope on Mauna Kea in Hawaii. It will soon give us information about magnetic fields in dense molecular clouds and star formation processes. We want to find out if magnetic fields are more important than turbulence (or vice versa) in slowing star formation processes, because observations show us that they are slower than what our models predict.

Areas of expertise

  • Star formation
  • Polarimetry
  • Young stars
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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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Doyon, René

DOYON, René

Professeur titulaire

Professor René Doyon’s research activities are focussed on the development of state-of-the-art astronomical instrumentation for various ground- and space-based observatories. He is also actively involved in various observational programs for detecting and characterizing brown dwarfs, exoplanets and young low-mass stars. On the instrumentation front, he leads several infrared instrumentation projects (camera and spectrograph) for the Observatoire du Mont-Mégantic. He is co-investigator of the Gemini Planet Imager, which has been operational since 2013.

He is also co-principal investigator of SPIRou, a high-resolution infrared spectrograph for the Canada-France-Hawaii Telescope. Scheduled for operation in 2015, SPIRou is designed to detect terrestrial (Earth-like) planets within the “habitable zone” of low-mass stars in the solar neighborhood. He is also principal investigator of NIRISS, one of the four scientific instruments on the James Webb Space Telescope.

Professor Doyon is the Director of the Institute for Research on exoplanets.

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Fontaine, Gilles

FONTAINE, Gilles

Professeur titulaire

Professor Gilles Fontaine’s research in astroseismology and stellar evolution recently led him to look at the fascinating challenges involved in characterizing exoplanets, one of the most important issues in contemporary astrophysics. Most of the time, an exoplanet’s properties cannot be determined unless the fundamental characteristics of its host star are known.

The astroseismological method is an excellent tool for this purpose and, if properly used, can determine the structural parameters of a variable star with great precision, along with its internal stratification and its age. Gilles Fontaine has begun to explore this research approach, which has already proven its merits on several occasions when planets have been discovered orbiting variable stars.

An impressive and growing number of white dwarfs seem to bear signs of planetary debris, opening the possibility of determining the bulk composition of these debris, a unique tool in planetology. The potential in this case is huge and very promising. White dwarfs play the role of a “substrate,” in a way, on which heavy elements constituting planetary debris are deposited, but a permeable substrate that allows the elements to pass through at different rates.

The first step is to determine the current abundance of these heavy elements in a given white dwarf. This calls for sophisticated atmospheric models, a specialty of Gilles Fontaine young colleague Patrick Dufour. Second, these levels of abundance (which vary over time) have to be interpreted with the possible accretion rates, the effects of differential diffusion among the different elements, the presence of convection zones, thermohaline convection and other mechanisms that can partially mix external layers and ultimately extend back to the primordial composition. This is a considerable challenge, but Professor Fontaine has already begun addressing it with a major review of calculations of diffusion coefficients that he did in 1986 in co-operation with Georges Michaud at the Université de Montréal. He is counting on the collaboration of expert numerical analyst Pierre Brassard. He hopes to be soon able to effectively simulate accretion-diffusion episodes of planetary debris on white dwarfs.

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Lafrenière, David

LAFRENIÈRE, David

Professeur agrégé

The study of exoplanets aims at establishing the prevalence and diversity of planetary systems in our galaxy, understanding how these systems form and evolve, comprehending the physics involved in their atmosphere and interior and, ultimately, detecting traces of life elsewhere in the universe. This is the main interest of Professor Lafrenière's group. The group's work is primarily performed using infrared imaging techniques that allow them to detect the planets directly, and then measuring their physical properties. To successfully "see" these very faint planets located right next to their host star, which can be several million times brighter, it is necessary to continually develop new observation and image processing techniques and even to build new instruments. With current technology, it is possible to detect gas giant planets with orbits of the outer solar system's size or larger.

In addition to direct imaging of planets, Professor Lafrenière's research group is also interested in the characterization of "hot Jupiter" planets by using transit/eclipse spectrophotometry and transit timing. The group is also involved in studies of brown dwarfs, in stellar and substellar multiplicity studies, and in searching for new young low-mass stars in the solar neighborhood.

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