Pier-Emmanuel Tremblay receives the 2012 Plaskett Medal

The Canadian Astronomical Society (CASCA) and the Royal Astronomical Society of Canada (RASC) awarded the J.S Plaskett Medal 2012 to Pier-Emmanuel Tremblay for the best 2012 Canadian PhD thesis in astrophysics.

Pier-Emmanuel Tremblay finished his PhD thesis in 2011 at the physics department at the Université de Montréal, under the supervision of Professor Pierre Bergeron. Dr. Tremblay’s thesis consisted in the study on white dwarf stars with hydrogen-rich atmospheres, also referred to as DA spectral type white dwarfs. More specifically, Pier-Emmanuel Tremblay improved the models of theoretical spectra of these stellar remnants, by including both a new implementation of non-ideal gas theory and Stark-broadening unified theory. By comparing the generated grid of models to the observed spectra of these DA white dwarfs (from the Sloan Digital Sky Survey), Dr. Tremblay significantly improved the determination of their atmospheric parameters (temperature and surface gravity). He also addressed a long-persisting problem in this field of research, the abnormally-high surface gravity that is measured in cold DA white dwarfs. By making use of high resolution spectra of white dwarfs obtained at the 10-m Keck telescopes (Hawaii), he demonstrated that the widely-accepted explanation for this phenomenon — Helium contamination of external layers of the atmosphere — is not supported by spectroscopic observations. Instead, Dr. Tremblay showed that the surface gravity anomalies can be solved by using hydrodynamic atmospheric models in three dimensions. Altogether, the results presented in the PhD thesis of Pier-Emmanuel Tremblay represent an important step in our understanding of white dwarfs with hydrogen-rich atmospheres.

Dr. Tremblay now works as a post-doctoral researcher with Professor Hans Ludwig at the University of Heidelberg (Germany), with whom he developed the first 3-dimensional atmospheric models for hydrogen rich white dwarfs. The prestigious Alexander von Humboldt postdoctoral fellowship he received in 2011 allowed him to make important progress in the understanding of these stars.

Several former student members of the Centre de Recherche en Astrophysique du Québec (CRAQ) have received the Plaskett Medal, including Pierre Bergeron (UdeM, 1990), Paul Charbonneau (UdeM, 1991), Pierre Brassard (UdeM, 1993), Alain Beauchamp (UdeM, 1997), Stéphane Charpinet (UdeM, 1999), Christian Marois (UdeM, 2005), Frédéric Grandmont (ULaval, 2007). The CRAQ is proud to say that its members (and former members) have received 8 out of the 25 annual Plaskett Medals.

The CRAQ congratulates Pier-Emmanuel Tremblay for the prestigious award.

About the Plaskett Medal
The Canadian Astronomical Society (CASCA) and the Royal Astronomical Society of Canada (RASC) inaugurated a price, the Plaskett Medal, in recognition of the important role played by John Stanley Plaskett (1865-1941) in the development of astrophysical research in Canada. The price, consisting of a gold medal, is awarded each year to the PhD graduate from a Canadian university with the most remarkable PhD thesis in astrophysics in the preceding two years. The laureate is then invited to give a conference lecture at the CASCA annual meeting.

Olivier Hernandez
Centre de recherche en astrophysique du Québec
Phone : (514) 343 6111 est 4681

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