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Je donne

Rechercher

Natural Sciences and Engineering; Engineering

Patrick Dufour

Study of the atmosphere of white dwarf stars

Professeur agrégé

Faculté des arts et des sciences - Département de physique

Roger-Gaudry, room D-440

514 343-7355

patrick.dufour@umontreal.ca

Secondary email: dufourpa@astro.umontreal.ca (Travail)

Media

Pourquoi a-t-on la voix aiguë lorsqu'on inhale de l'hélium ?

Patrick Dufour, professeur au Département de physique de l'Université de Montréal, nous explique comment l'hélium influence le son de notre voix.

Profile

Research expertise

My research is oriented mainly toward the study of white dwarf atmospheres, from both the theoretical (detailed model atmosphere calculations) and observational (spectroscopic and photometric observations) viewpoints. White dwarfs are the remnants of low-mass stars that have used up their reserves of nuclear fuel. A typical white dwarf consists of a nucleus of carbon and oxygen representing over 99% of its mass, surrounded by a thin layer of helium that is itself surrounded, in about 80% of cases, by another thin layer of hydrogen. These layers, although thin, are optically opaque and regulate the rate at which the star loses energy (i.e. its cooling rate). To properly understand the evolution of white dwarfs, it is essential to understand the physical properties of these surface layers. The spectroscopic analysis of light from white dwarfs' atmospheres is the main technique used to gather information on the external parts of white dwarfs. My work is focussed on analyzing stars with traces of heavy elements (DZ and DQ spectral types) and stars with a carbon atmosphere.

Awards and recognitions

  • 10 découvertes de l'année 2016 de la revue Québec Science

Affiliations and responsabilities

University service and activities

Activities within organizations or entities of the institution

Teaching and supervision

Student supervision

Theses and dissertation supervision (Papyrus Institutional Repository)

2019

Modélisation des effets de haute densité à la photosphère des naines blanches froides

Graduate : Blouin, Simon
Cycle : Doctoral
Grade : Ph. D.
2017

Modélisation d'étoiles naines blanches magnétiques éléments lourds

Graduate : Hardy, François
Cycle : Master's
Grade : M. Sc.

Projects

Research projects

2020 - 2026

Detailed bulk composition analysis of extrasolar objects accreted at the surface of white dwarf stars

Lead researcher : Patrick Dufour
Funding sources: CRSNG/Conseil de recherches en sciences naturelles et génie du Canada (CRSNG)
Grant programs: PVX20965-(RGP) Programme de subvention à la découverte individuelle ou de groupe
2017 - 2024

Centre de recherche en astrophysique du Québec (CRAQ)

Lead researcher : Pierre Bergeron
Funding sources: FRQNT/Fonds de recherche du Québec - Nature et technologies (FQRNT)
Grant programs: PVXXXXXX-(RS) Programme de regroupements stratégiques
2013 - 2021

ANALYSE DE NAINES BLANCHES A ATMOSPHERE DOMINEE PAR LE CARBONE

Lead researcher : Patrick Dufour
Funding sources: CRSNG/Conseil de recherches en sciences naturelles et génie du Canada (CRSNG)
Grant programs: PVX20965-(RGP) Programme de subvention à la découverte individuelle ou de groupe
2016 - 2018

Centre de recherche en astrophysique du Québec (CRAQ)

Lead researcher : Pierre Bergeron
Funding sources: FRQNT/Fonds de recherche du Québec - Nature et technologies (FQRNT)
Grant programs: PVXXXXXX-(RS) Programme de regroupements stratégiques
2015 - 2018

Modélisation des étoiles naines blanches froides dans un régime à très grande densité

Lead researcher : Patrick Dufour
Funding sources: FRQNT/Fonds de recherche du Québec - Nature et technologies (FQRNT)
Grant programs: PVXXXXXX-(NC) Établissement de la relève professorale
2014 - 2018

AUTOPSIES D'ANCIENS SYSTEMES PLANETAIRES À PARTIR DES ETOILES NAINES BLANCHES

Lead researcher : Patrick Dufour
Co-researchers : Pierre Bergeron , Gilles Fontaine
Funding sources: FRQNT/Fonds de recherche du Québec - Nature et technologies (FQRNT)
Grant programs: PV113724-(PR) Projets de recherche en équipe (et possibilité d'équipement la première année)
2008 - 2017

CENTRE DE RECHERCHE EN ASTROPHYSIQUE DU QUEBEC

Lead researcher : Pierre Bergeron
Funding sources: FRQNT/Fonds de recherche du Québec - Nature et technologies (FQRNT)
Grant programs: PVXXXXXX-(RS) Programme de regroupements stratégiques

Outreach

Publications and presentations

Publications

Chapitre de livre
Stars with Unusual Compositions: Carbon and Oxygen in Cool White Dwarfs
P. Dufour (Chap. 3) “White Dwarf Atmosphere and Circumstellar Environments”, D. W. Hoard (Ed.), Wiley-VCH, ISBN 978-3-527-41031-6 (Amazon)

Articles avec comité de lecture (2013 à 2011)

44-SDSS J074511.56+194926.5: Discovery of a Metal-Rich and Tidally Distorted Extremely Low Mass White Dwarf
Gianninas, A.; Hermes, J. J.; Brown, Warren R.; Dufour, P.; Barber, Sara D.; Kilic, Mukremin; Kenyon, Scott J.; Harrold, Samuel T.
accepted for publication in ApJ  (ADS)

43-Accretion and activity on the post-common-envelope binary RR Caeli
Ribeiro, T.; Baptista, R.; Kafka, S.; Dufour, P.; Gianninas, A.; Fontaine, G.
Astronomy & Astrophysics, Volume 556, 2013.  (ADS)

42-SDSS J000555.90-100213.5: a hot, magnetic carbon-dominated atmosphere WD rotating with a 2.1 d period
Lawrie, K. A.; Burleigh, M. R.; Dufour, P.; Hodgkin, S. T.
Monthly Notices of the Royal Astronomical Society, Advance Access. 8 pp., 2013 (ADS)

41-Hubble Space Telescope Imaging of the Binary Nucleus of the Planetary Nebula EGB 6
Liebert, James; Bond, Howard E.; Dufour, P.; Ciardullo, Robin; Meakes, Michael G.; Renzini, Alvio; Gianninas, A.
The Astrophysical Journal, Volume 769, Issue 1, 2013. (ADS)

40-Photometric variability in a warm, strongly magnetic DQ white dwarf, SDSS J103655.39+652252.2
Williams, Kurtis A.; Winget, D. E.; Montgomery, M. H.; Dufour, Patrick; Kepler, S. O.; Hermes, J. J.; Falcon, Ross E.; Winget, K. I.; Bolte, Michael; Rubin, K. H. R.
The Astrophysical Journal, Volume 769, Issue 2, 2013 (ADS)

39-Orbital and Evolutionary Constraints on the Planet Hosting Binary GJ 86 from the Hubble Space Telescope
Farihi, J.; Bond, Howard E.; Dufour, P.; Haghighipour, N.; Schaefer, G. H.; Holberg, J. B.; Barstow, M. A.; Burleigh, M. R.
Monthly Notices of the Royal Astronomical Society, Volume 430, 2013. (ADS)

38-SDSS DR7 White Dwarf Catalog
Kleinman, S. J.; Kepler, S. O.; Koester, D.; Pelisoli, Ingrid; Peçanha, Viviane; Nitta, A.; Costa, J. E. S.; Krzesinski, J.; Dufour, P.; Lachapelle, F.-R.; Bergeron, P.; Yip, Ching-Wa; Harris, Hugh C.; Eisenstein, Daniel; Althaus, L.; Córsico, A.
The Astrophysical Journal Supplement, Volume 204, Issue 1, 2013. (ADS)

37-The Frequency of Debris Disks at White Dwarfs
Barber, Sara D.; Patterson, Adam J.; Kilic, Mukremin; Leggett, S. K.; Dufour, P.; Bloom, J. S.; Starr, D. L.
The Astrophysical Journal, Volume 760, Issue 1, 2012. (ADS)

36-Gaseous Material Orbiting the Polluted, Dusty White Dwarf HE1349-2305
Melis, Carl; Dufour, P.; Farihi, J.; Bochanski, J.; Burgasser, Adam J.; Parsons, S.; Gaensicke, B.; Koester, D.; Swift, Brandon
The Astrophysical Journal Letters, Volume 751, Issue 1, 2012. (ADS)

35-A Multi-survey Approach to White Dwarf Discovery
Sayres, Conor; Subasavage, John P.; Bergeron, P.; Dufour, P.; Davenport, James R. A.; AlSayyad, Yusra; Tofflemire, Benjamin M.
The Astronomical Journal, Volume 143, Issue 4, 2012. (ADS)

34-Know Your Neighborhood: A Detailed Model Atmosphere Analysis of Nearby White Dwarfs
Giammichele, N.; Bergeron, P.; Dufour, P.
The Astrophysical Journal Supplement, Volume 199, Issue 2, 2012. (ADS)

33-Detailed compositional analysis of the heavily polluted DBZ white dwarf SDSS J073842.56+183509.06: A window on planet formation?
Dufour, P.; Kilic, M.; Fontaine, G.; Bergeron, P.; Melis, C.; Bochanski, J.
The Astrophysical Journal, Volume 749, Issue 1, 2012. (ADS)

32-The Discovery of a Debris Disk Around the DAV White Dwarf PG 1541+651
Kilic, Mukremin; Patterson, Adam J.; Barber, Sara; Leggett, S. K.; Dufour, P.
Monthly Notices of the Royal Astronomical Society: Letters, Volume 419, Issue 1, pp. L59-L63, 2012. (ADS)

31-Stark Broadening of Carbon and Oxygen Lines in Hot DQ White Dwarf Stars: Recent Results and Applications
Dufour, P.; Ben Nessib, N.; Sahal-Bréchot, S.; Dimitrijević, M. S.
Baltic Astronomy, Vol. 20, p. 511-515 (ADS)

30-An aluminum/calcium-rich, iron-poor, white dwarf star: evidence for an extrasolar planetary lithosphere?
Zuckerman, B.; Koester, D.; Dufour, P.; Melis, Carl; Klein, B.; Jura, M.
The Astrophysical Journal, Volume 739, Issue 2, 2011. (ADS)

29-A Comprehensive Spectroscopic Analysis of DB White Dwarfs
Bergeron, P.; Wesemael, F.; Dufour, Pierre; Beauchamp, A.; Hunter, C.; Saffer, Rex A.; Gianninas, A.; Ruiz, M. T.; Limoges, M. -M.; Dufour, Patrick; Fontaine, G.; Liebert, James
The Astrophysical Journal, Volume 737, Issue 1, 2011. (ADS)

28-Cool DZ white dwarfs in the SDSS
Koester, D.; Girven, J.; Gänsicke, B. T.; Dufour, P.
Astronomy & Astrophysics, Volume 530, 2011. (ADS)

27-Taking Advantage of the COS Time-Tag Capability: Observations of Pulsating Hot DQ White Dwarfs and Discovery of a New One
Dufour, P.; Béland, S.; Fontaine, G.; Chayer, P.; Bergeron, P.
The Astrophysical Journal Letters, Volume 733, Issue 2, 2011. (ADS)

26-Accretion of a Terrestrial-Like Minor Planet by a White Dwarf
Melis, Carl; Farihi, J.; Dufour, P.; Zuckerman, B.; Burgasser, Adam J.; Bergeron, P.; Bochanski, J.; Simcoe, R.
The Astrophysical Journal, Volume 732, Issue 2, 2011. (ADS)

25-The Magnetic and Metallic Degenerate G77-50
Farihi, J.; Dufour, P.; Napiwotzki, R.; Koester, D.
Monthly Notices of the Royal Astronomical Society, 2011  (ADS)

24-Discovery of a new AM CVn system with the Kepler satellite
Fontaine, G.;Brassad, P.; Green, E.M.; Charpinet, S.; Dufour, P.; Hubeny, I.; Steeghs, D.; Aerts, C.; Randall, S.K.; Bergeron, P.; Guvenen, B.; O'Malley, C.J.; Van Grootel, V.; Ostensen, R.H.; Bloemen, S.; Silvotti, R.; Howell, S.B.; Baran, A.; Kepler, S.O.; Marsh, T.R.; Montgomery, M.H.; Oreiro, R.; Provencal, J.; Telting, J.; Winget, D.E.; Zima, W.; Christensen-Dalsgaard, J.; Kjeldsen, H.
The Astrophysical Journal, Volume 726, Issue 2, 2011. (ADS)

Disciplines

  • Physics
  • Astronomy and Astrophysics

Areas of expertise

  • Fundamental astronomy
  • Photography and photometry
  • Spectroscopy and spectrophotometry
  • Pulsations, oscillations, and stellar seismology
  • Stellar characteristics and properties
  • Stellar atmospheres
  • Radiative transfer
  • Opacity and line formation
  • Abundance, chemical composition
  • Stellar structure, interiors, evolution, nucleosynthesis, ages
  • Faint blue stars, White dwarfs, degenerate stars, nuclei of planetary nebulae