I am an NSERC Postdoctoral FellowLink opens in a new window in the Astronomy and Astrophysics group at the University of Warwick, working within the white dwarf research groupLink opens in a new window with Pier-Emmanuel TremblayLink opens in a new window. I am interested in theoretical stellar astrophysics and its application to white dwarfs, with the aim of using these stellar remnants as probes of Galactic, stellar, and planetary evolution.

Research

White dwarfs are ubiquitous stellar remnants that cool continuously over billions of years and thereby act as "cosmic clocks". They thus provide a powerful way to study the formation and evolution of stars and planets over the history of the Galaxy. However, exploiting this potential requires a thorough understanding of their physical properties, in particular their cooling process.

My current research primarily focuses on the development of detailed models of the structure and evolution of white dwarfs, based on state-of-the-art physical theories and numerical techniques. I am especially interested in the phenomenon of core crystallisation (a phase transition that causes the stellar core to solidify into a crystal) and its influence on the cooling process. I also study the complex effects of chemical element transport in the stellar envelope (due to diffusion, convection, and winds) on the evolution of white dwarfs.

Furthermore, I am interested in the analysis of the hundreds of thousands of white dwarfs recently discovered by the Gaia satelliteLink opens in a new window in the local region of the Galaxy. I build and use atmospheric models to interpret photometric and spectroscopic observations of white dwarfs and thereby determine their fundamental stellar parameters (such as mass, temperature, composition, and age). I pay particular attention to white dwarf binary systems, which are sources of gravitational waves and supernovae and thus provide important clues about these phenomena.

Publications

Full list in NASA ADSLink opens in a new window

• Tremblay, P.-E., Bédard, A., O'Brien, M. W., Munday, J., Elms, A. K., Gentillo Fusillo, N. P., Sahu, S., 2024, NewAR, 99, 101705. The Gaia white dwarf revolutionLink opens in a new window
• Munday, J., Pelisoli, I., Tremblay, P. -E., Marsh, T. R., Nelemans, G., Bédard, A., Toonen, S., Breedt, E., Cunningham, T., O'Brien, M., & Dawson, H., 2024, MNRAS, 532, 2534. The DBL Survey I: discovery of 34 double-lined double white dwarf binariesLink opens in a new window
• Bédard, A., 2024, Ap&SS, 369, 43. The spectral evolution of white dwarfs: where do we stand?Link opens in a new window
• Bédard, A., Blouin, S., & Cheng, S., 2024, Nature, 627, 286. Buoyant crystals halt the cooling of white dwarf starsLink opens in a new window (Press release: Astrophysicists unveil new phenomenon challenging textbook definition of white dwarf starsLink opens in a new window)
• Werner, K., Reindl, N., Rauch, T., El-Badry, K., & Bédard, A., 2024, A&A, 682, A42. The photospheres of the hottest fastest stars in the GalaxyLink opens in a new window
• O'Brien, M. W., & Tremblay, P.-E., Klein, B. L., Koester, D., Melis, C., Bédard, A., Cukanovaite, E., Cunningham, T., Doyle, A. E., Gänsicke, B. T., Gentile Fusillo, N. P., Hollands, M. A., McCleery, J., Pelisoli, I., Toonen, S., Weinberger, A. J., & Zuckerman, B., 2024, MNRAS, 527, 8687. The 40 pc sample of white dwarfs from GaiaLink opens in a new window
• Blouin, S., Kilic, M., Bédard, A., & Tremblay, P.-E., 2023, MNRAS, 525, L112. The ubiquity of carbon dredge-up in hydrogen-deficient white dwarfs as revealed by GALEXLink opens in a new window
• Elms, A. K., Tremblay, P.-E., Gänsicke, B. T., Swan, A., Melis, C., Bédard, A., Manser, C. J., Munday, J., Hermes, J. J., Dennihy, E., Nitta, A., & Zuckerman, B., 2023, MNRAS, 524, 4996. An emerging and enigmatic spectral class of isolated DAe white dwarfsLink opens in a new window
• Venner, A., Blouin, S., Bédard, A., & Vanderburg, A., 2023, MNRAS, 523, 4624. A crystallizing white dwarf in a Sirius-like quadruple systemLink opens in a new window
• Blouin, S., Bédard, A., & Tremblay, P.-E., 2023, MNRAS, 523, 3363. Carbon dredge-up required to explain the Gaia white dwarf colour-magnitude bifurcationLink opens in a new window
• Kosakowski, A., Brown, W. R., Kilic, M., Kupfer, T., Bédard, A., Gianninas, A., Agüeros, M. A., & Barrientos, M., 2023, ApJ, 950, 141. The ELM Survey South. II. Two Dozen New Low-mass White Dwarf BinariesLink opens in a new window
• Bédard, A., Bergeron, P., & Brassard, P., 2023, ApJ, 946, 24. On the Spectral Evolution of Hot White Dwarf Stars. IV. The Diffusion and Mixing of Residual Hydrogen in Helium-rich White DwarfsLink opens in a new window
• Bergeron, P., Kilic, M., Blouin, S., Bédard, A., Leggett, S. K., & Brown, W. R., 2022, ApJ, 934, 36. On the Nature of Ultracool White Dwarfs: Not so Cool after AllLink opens in a new window
• Bédard, A., Bergeron, P., & Brassard, P., 2022, ApJ, 930, 8. On the Spectral Evolution of Hot White Dwarf Stars. III. The PG 1159-DO-DB-DQ Evolutionary Channel RevisitedLink opens in a new window
• Bédard, A., Brassard, P., Bergeron, P., & Blouin, S., 2022, ApJ, 927, 128. On the Spectral Evolution of Hot White Dwarf Stars. II. Time-dependent Simulations of Element Transport in Evolving White Dwarfs with STELUMLink opens in a new window
• Bergeron, P., Wesemael, F., Fontaine, G., Lamontagne, R., Demers, S., Bédard, A., Gingras, M.-J., Blouin, S., Irwin, M. J., & Kepler, S. O., 2021, AJ, 162, 188. Hot Degenerates in the MCT Survey. III. A Sample of White Dwarf Stars in the Southern HemisphereLink opens in a new window
• Barnett, J. W., Williams, K. A., Bédard, A., & Bolte, M., 2021, AJ, 162, 162. The Initial-Final Mass Relation for Hydrogen-deficient White DwarfsLink opens in a new window
• Kilic, M., Brown, W. R., Bédard, A., & Kosakowski, A., 2021, ApJL, 918, L14. The Discovery of Two LISA Sources within 0.5 kpcLink opens in a new window
• Kilic, M., Bergeron, P., Blouin, S., & Bédard, A., 2021, MNRAS, 503, 5397. The most massive white dwarfs in the solar neighbourhoodLink opens in a new window
• Kilic, M., Bédard, A., & Bergeron, P., 2021, MNRAS, 502, 4972. Hidden in plain sight: a double-lined white dwarf binary 26 pc away and a distant cousinLink opens in a new window
• Kaiser, B. C., Clemens, J. C., Blouin, S., Dufour, P., Hegedus, R. J., Reding, J. S., & Bédard, A., 2021, Science, 371, 168. Lithium pollution of a white dwarf records the accretion of an extrasolar planetesimalLink opens in a new window
• Gagné, J., David, T. J., Mamajek, E. E., Mann, A. W., Faherty, J. K., & Bédard, A., 2020, ApJ, 903, 96. The mu Tau Association: A 60 Myr Old Coeval Group at 150 pc from the SunLink opens in a new window
• Bédard, A., Bergeron, P., Brassard, P., & Fontaine, G., 2020, ApJ, 901, 93. On the Spectral Evolution of Hot White Dwarf Stars. I. A Detailed Model Atmosphere Analysis of Hot White Dwarfs from SDSS DR12Link opens in a new window
• Klein, B., Blouin, S., Romani, D., Zuckerman, B., Melis, C., Xu, S., Dufour, P., Genest-Beaulieu, C., Bédard, A., & Jura, M., 2020, ApJ, 900, 2. Atmospheric Temperature Inversions and He I 5876 Core Profile Structure in White DwarfsLink opens in a new window
• Blouin, S., Daligault, J., Saumon, D., Bédard, A., & Brassard, P., 2020, A&A, 640, L11. Toward precision cosmochronology. A new C/O phase diagram for white dwarfsLink opens in a new window
• Brown, W. R., Kilic, M., Bédard, A., Kosakowski, A., & Bergeron, P., 2020, ApJL, 892, L35. A 1201 s Orbital Period Detached Binary: The First Double Helium Core White Dwarf LISA Verification BinaryLink opens in a new window
• Kilic, M., Bédard, A., Bergeron, P., & Kosakowski, A., 2020, MNRAS, 493, 2805. Two new double-lined spectroscopic binary white dwarfsLink opens in a new window
• Bergeron, P., Dufour, P., Fontaine, G., Coutu, S., Blouin, S., Genest-Beaulieu, C., Bédard, A., & Rolland, B, 2019, ApJ, 876, 67. On the Measurement of Fundamental Parameters of White Dwarfs in the Gaia EraLink opens in a new window
• Bond, H. E., Bergeron, P., & Bédard, A., 2017, ApJ, 848, 16. Astrophysical Implications of a New Dynamical Mass for the Nearby White Dwarf 40 Eridani BLink opens in a new window
• Bédard, A., Bergeron, P., & Fontaine, G., 2017, ApJ, 848, 11. Measurements of Physical Parameters of White Dwarfs: A Test of the Mass-Radius RelationLink opens in a new window

Talks and seminars

• Distillation as the explanation for the Gaia Q branch, 23^rd European Workshop on White Dwarfs (July 2024, Barcelona, Spain)
• The spectral evolution of white dwarf stars: a journey at the crossroads of physics and astronomy, annual meeting of the Canadian Astronomical Society (June 2024, Toronto, Canada)
• The physics of white dwarf interiors, Current Challenges in the Physics of White Dwarf Stars (March 2024, Santa Fe, USA)
• The transport of chemical elements in white dwarfs as revealed by Gaia, seminar, University of Victoria (March 2024, Victoria, Canada)
• The transport of chemical elements in white dwarfs as revealed by Gaia, seminar, Laboratoire d'Astrophysique de Bordeaux (December 2023, Bordeaux, France)
• A detailed modeling of the DO-to-DA spectral evolution, 22^nd European Workshop on White Dwarfs (August 2022, Tübingen, Germany)
• The spectral evolution of white dwarf stars: a unique window on element transport in stars, seminar, Université de Montréal (March 2022, Montréal, Canada)
  
• Element transport in evolutionary models: a new look at the spectral evolution of white dwarfs, Online Meetings on Evolved Stars and Systems (April 2021, remote)
• The spectral evolution of hot white dwarfs, 357^th Symposium of the International Astronomical Union: White Dwarfs as Probes of Fundamental Physics and Tracers of Planetary, Stellar, and Galactic Evolution (October 2019, Hilo, USA)
• The spectral evolution of hot white dwarf stars, annual meeting of the Canadian Astronomical Society (June 2019, Montréal, Canada)
• The spectral evolution of hot white dwarf stars, annual meeting of the Centre de Recherche en Astrophysique du Québec (May 2019, Saint-Alexis-des-Monts, Canada)
• A non-LTE model-atmosphere analysis of hot hydrogen-deficient white dwarfs, Hydrogen-Deficient Stars 2018 (September 2018, Armagh, UK)
• Testing the theoretical mass-radius relation of white dwarf stars, annual meeting of the Centre de Recherche en Astrophysique du Québec (May 2018, Saint-Alexis-des-Monts, Canada)