My research is aimed mainly at understanding magnetic fields in stars: how they are structured, how they influence the stellar plasma in which they are embedded, how they evolve, and where they came from in the first place. My approach is primarily observational, and I exploit powerful telescopes and spectropolarimetric instrumentation at observatories around the world.

I am a member and Treasurer of the Canadian Astronomical Society (CASCA), and a member of the International Astronomical Union (IAU). I am also a co-editor of A Peculiar Newsletter, the official circular of the IAU Working Group on Ap and Related Stars. I am ajunct Professor of Physics at Queen's University and Université Laval.

My research relies on extensive collaborations with researchers around the world. My collaborators include Stefano Bagnulo at Armagh Observatory (Northern Ireland), John Landstreet at the University of Western Ontario (London, Canada), Michel Aurière, Jean-Francois Donati, Alain Hui-Bon-Hoa, Pascal Petit and Torsten Boehm at the Observatoire Midi-Pyrénées (Toulouse and Tarbes, France), Tanya Ryabchikova at the Astronomical Institute (Moscow, Russia), Francis LeBlanc at Université de Moncton (Moncton, Canada), and Claude Catala at LESIA (Paris, France). I am PI of the CFHT’s MiMeS Large Program, and co-PI of the MagIcS initiative, an international collaboration of over 100 stellar astrophysicists working together to study the magnetic fields of various classes of stars throughout the HR diagram.

Current Research:

My current research focuses on two main themes:

   1. The origin and evolution of magnetic fields in intermediate-mass and high-mass stars.

Intermediate-mass and high-mass stars are distinguished by strong, organised magnetic fields which appear to be primarily fossil in origin - remnants of field accumulated or generated during the process of star formation. Due to the relic nature of their magnetic fields, massive stars provide us with the unique capability to study how fields evolve throughout the various phases of stellar evolution, and to explore how fields are influenced by the large variety of structural changes that occur during the pre-main sequence, main sequence, and post-main sequence evolutionary phases. My main interests lie in investigating the mechanisms leading to the appearance of fossil magnetic fields at the pre-main sequence phase, providing a physical context for understanding the observed systematic properties of magnetic and non-magnetic stars on the main sequence, and characterising the evolution of magnetic fields, potentially providing insight into the origin of magnetic fields in white dwarfs and neutron stars. An important current incarnation of this work is the Magnetism in Massive Stars (MiMeS) Large Program at the CFHT, of which I am PI.

   2. Chemical separation and mixing processes in atmospheres of pre-main sequence, main sequence and post-main sequence A and B type stars.

The zoo of chemical abundance peculiarities observed in the

spectra of A and B stars results from competition between a host of poorly-understood chemical separation and mixing processes operating in their outer layers. These include gravitational settling, radiative levitation, convection and small-scale turbulent mixing, large-scale rotational circulation currents, mass loss and magnetic fields. My current interests involve modeling stratification of chemical elements in the atmospheres of magnetic Ap stars and Blue Horizontal Branch stars, characterising the development of chemical peculiarities in magnetic and non-magnetic pre-main sequence stars, and studying the evolution of chemical peculiarity in main sequence stars.

GRADUATE STUDENTS:

I currently supervise or co-supervise 1 MSc student and 3 PhD students, all of whom are civilians.

James Silvester (Queen's) is in the final year of his PhD, which is focused on Magnetic Doppler Imaging of a sample of Ap/Bp stars using data acquired with both the ESPaDOnS instrument at the Canada-France-Hawaii Telescope (CFHT), and the NARVAL instrument at the Pic du Midi observatory. The amazing new magnetic and chemical maps that James is producing will totally revolutionise our view of structures in the atmospheres of Ap stars. James also completed his MSc under my supervision, exploiting open clusters to explore the evolution and environmental dependence of chemical peculiarities and magnetic fields in Ap/Bp stars. For his MSc, James used data obtained with the MuSiCoS instrument at Pic du Midi observatory. James spent the fall term of 2006 in Chile in tenure of an ESO Short-Term Studentship, under the supervision of Stefano Bagnulo.

Jason Grunhut (Queen's) is in the third year of his PhD, which focuses on data analysis and interpretation in support of  the MiMeS Large Program. Jason joined us in 2006 from the David Dunlap Observatory at University of Toronto, where he was performing observational research into the properties of hot stars under the supervision of Prof. Tom Bolton. He also completed his MSc thesis under my supervision. For his MSc, Jason explored the potential of high-resolution ESPaDOnS spectra of Herbig Ae/Be stars to constrain the fundamental properties of those objects.

Matt Schulz (Queen's) is in the second year of his MSc, which also  focuses on data analysis and interpretation in support of the MiMeS Large Program.  Matt’s thesis is a component of the international “Rigel-thon”: a multi-site, multi-instrument study of the late-B supergiant Rigel, with the aim of studying this star’s magnetic field, pulsations, and wind structure and variability.

James, Jason and Matt are all co-supervised by Dave Hanes at Queen's University. Véronique is co-supervised by Laurent Drissen at Laval University.

Research STAFF:

Poonam Chandra joined us in October 2008. Poonam is an expert in the physics of supernovae and gamma-ray bursts, which she studies using X-ray and radio telescopes. She is co-supervised by Prof. Kristine Spekkens of RMC. Poonom is an ajunct assistant professor at RMC, and was recently awarded the IUPAP Young Scientist prize in astrophysics for her work on radio detections of distant gamma-ray bursts and supernovae.

FORMER GRADUATE sTUDENTS:

Véronique Petit: Véronique is a a postdoctoral research er at West Chester University. She is also the recipient of an FQRNT Postdoctoral Fellowship from the province of Québec. Her PhD thesis focusesed on the magnetic fields of massive stars, in particular the magnetic properties of the massive stars of the Orion Nebula Cluster.

Katherine Likuski: Katherine completed her MSc characterising the spectral, physical and magnetic properties of the SB2 binary system HD 98088 in May 2009. Katherine is an officer in the Canadian Forces who completed her undergraduate studies at RMC.

Jason Grunhut: Jason completed his thesis “Using high-resolution spectroscopy to improve the determination of effective temperatures of Herbig Ae/Be stars” under my supervision in December 2008. He is now a PhD student with me.

Mouhamadou Thiam: Ameth Thiam Completed his MSc thesis entitled “Abondances et stratification des éléments dans les atmosphères des étoiles mercure-manganèse” under my co-supervision in 2008. He subsequently completed a degree in education at l’Université de Moncton.

Jenny Power: Jenny completed her MSc thesis "A volume-limited sample of magnetic Ap/Bp stars" under my co-supervision in August 2007. Jenny is now an observing assistant at the Kitt Peak National Observatories in Arizona, USA.

Colin Folsom: Colin completed his MSc thesis "Magnetic, chemical and rotational properties of the Herbig Ae/Be binary system HD 72106" under my co-supervision in August 2007. He is now a PhD student at Armagh Observatory, Northern Ireland.

James Silvester: James completed his MSc thesis "Where have all the Ap stars gone?" under my co-supervision in May 2007. He is now a PhD student with me.

Dominic Drouin: Dominic completed his MSc thesis "Seeking the progenitors of the magnetic Ap/Bp stars" under my supervision in April 2005. Dominic is now a Captain and Hercules pilot in the Canadian Forces.

Noemie Johnson: Noemie completed her MSc thesis "Why are there so few cool Ap stars?" under my supervision in April 2004. Noemie is now a Captain in the Canadian Forces, and attending medical school at Sherbrooke University.

FORMER RESEARCH STAFF:

Véronique Petit: From September 2009-June 2010, while editing her PhD thesis in preparation for submission, Véronique Petit held the position of Research Associate and Lecturer at RMC. During this time she taught PHF 352 (Astronomie) and the first-year introductor physics laboratory. Véronique is now FQRNT Fellow and teaching staff at Westchester University in Philadephia, USA.

Evelyne Alécian: Evelyne was a Marie Curie International postdoctoral fellow at RMC from February 2007 - February 2009. She currently holds an ESO postdoctoral fellowship at Observatoire de Grenoble. In January, she will begin a new permanent position as CNRS Chargé de Recherche at Observatoire de Paris (Meudon), at the LESIA lab.

Viktor Khalack: I co-supervised Viktor’s research in cooperation with Francis LeBlanc from 2005-2006. Viktor’s work focused on diffusion and stratification in the atmospheres of Blue Horizontal Branch stars. Viktor currently teaches and pursues research in and around Moncton, New Brunswick.

Dmitry Monin: I co-supervised Dmitry’s research in cooperation with John Landstreet from 2003-2004. Dmitry’s work focused on magnetic fields in main sequence and white dwarf stars. Dmitry is now a permanent Technical Officer at the Dominion Astrophysical Observatory in Victoria, British Columbia.