Georges Michaud
- Professeur émérite
-
Faculté des arts et des sciences - Département de physique
Courriels
michaudg@astro.umontreal.ca (Travail)
Travail 2 : 514 369-5261
Travail 1 : 514 343-6672
Affiliations
Areas of Expertise
- Stellar
- Elementary Particles
- Atmosphere (Including Chemical Aspects)
- Chemical Composition
- Chemical Processes
- Modelization and Simulation
- Theory for calculus
We have introduced atomic diffusion into a stellar evolution code and obtain stellar models where particle transport is treated in the radiative zones. Radiative accelerations are calculated self consistently using the atomic data originally used by OPAL to obtain their opacity tables.
In Pop I stars it has been shown that an iron convection zone appears in all F, A and B stars where rotation and mass loss are negligible. By increasing the mass of the convective core, atomic diffusion modifies the morphology of the turnoff and the assumption of core overshoot in solar metallicity clusters such as M67 becomes unnecessary. We are currently investigating the role of mass loss as a competing process in particular for AmFm stars and the effect of the suggested change of solar metallicity on cluster morphology.
In Pop II stars, the evolution has been carried out successfully from the zero age main sequence to the middle of the horizontal branch. It has been shown that the assumption of core overshoot, which has always been made since suggested in 1970, is unnecessary since atomic diffusion of Carbon from the core is sufficient to insure convective neutrality at the helium burning core boundary causing a 50 % increase in the mass of the convective core. It has furthermore been shown that the overabundance of, for instance, iron by a factor of ~100 in the hot horizontal branch stars of M15 is explained by atomic diffusion driven by radiative accelerations. We are currently extending the calculations to the end of the horizontal branch and beyond and study the effect of varying the metallicity on the properties of the horizontal branch of clusters where abundance anomalies have been observed. These calculations will also be compared to observations of field sdB stars. A complete grill of models is being generated for Pop II stars and they will be used to interpret the implications of WMAP for the Li abundance, taking into account the latest developments.
Student supervision Expand all Collapse all
Research projects Expand all Collapse all
CALCUL QUEBEC Projet de recherche au Canada / 2015 - 2023
Centre de recherche en astrophysique du Québec (CRAQ) Projet de recherche au Canada / 2016 - 2018
CENTRE DE RECHERCHE EN ASTROPHYSIQUE DU QUEBEC Projet de recherche au Canada / 2008 - 2017
EVOLUTION STELLAIRE ET PROCESSUS HYDRODYNAMIQUES DE TRANSPORT Projet de recherche au Canada / 1994 - 2017
ÉVOLUTION STELLAIRE ET PROCESSUS HYDRODYNAMIQUES DE TRANSPORT Projet de recherche au Canada / 2011 - 2015
Recognition and Awards
- Prix Marcel-Vincent, Association francophone pour le savoir (Acfas), 1979.
- Bourse Killam, Conseil des arts du Canada, 1987.
- Société royale du Canada : Les Académies des arts, des lettres et des sciences du Canada, Société royale du Canada, 1992.
Additional Information
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