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Classification and parameterisation of a large Gaia sample of white dwarfs using XP spectra
O. Vincent, M. A. Barstow, S. Jordan +3
The latest Gaia data release in July 2022, DR3, added a number of important data products to those available in earlier releases, including radial velocity data, information on ste…
Measurement of stellar and substellar winds using white dwarf hosts
N. Walters, J. Farihi, P. Dufour +2
White dwarfs stars are known to be polluted by their active planetary systems, but little attention has been paid to the accretion of wind from low-mass companions. The capture of…
Disk or Companion: Characterizing Excess Infrared Flux in Seven White Dwarf Systems with Near-Infrared Spectroscopy
Dylan Owens, Siyi Xu, Elena Manjavacas +7
Excess infrared flux from white dwarf stars is likely to arise from a dusty debris disk or a cool companion. In this work, we present near-infrared spectroscopic observations with…
New chondritic bodies identified in eight oxygen-bearing white dwarfs
Alexandra E. Doyle, Beth L. Klein, Patrick Dufour +8
We present observations and analyses of eight white dwarf stars that have accreted rocky material from their surrounding planetary systems. The spectra of these helium-atmosphere w…
Spectrophotometric analysis of magnetic white dwarf II: Helium-rich compositions
François Hardy, Patrick Dufour, Stefan Jordan
We present an analysis of all single white dwarf stars known to exhibit spectroscopic signatures of neutral helium line splitting due to the presence of a strong magnetic field. Us…
Spectrophotometric analysis of magnetic white dwarf I: Hydrogen-rich compositions
François Hardy, Patrick Dufour, Stefan Jordan
We present an homogeneous analysis of all DA stars labeled as magnetic in the Montreal White Dwarf Database (MWDD). Our sample is restricted to almost all known magnetic white dwar…
Data-Driven Selection and Spectral Classification of White Dwarf Stars
Olivier Vincent, Pierre Bergeron, Patrick Dufour
The next generation of spectroscopic surveys is expected to provide spectra for hundreds of thousands of white dwarf (WD) candidates in the upcoming years. Currently, spectroscopic…
The Merger Fraction of Ultramassive White Dwarfs
Mukremin Kilic, Adam G. Moss, Alekzander Kosakowski +6
We search for merger products among the 25 most massive white dwarfs in the Montreal White Dwarf Database 100 pc sample through follow-up spectroscopy and high-cadence photometry.…
Missing Metals in DQ Stars; a Compelling Clue to their Origin
J. Farihi, P. Dufour, T. G. Wilson
White dwarf stars frequently experience external pollution by heavy elements, and yet the intrinsically carbon-enriched DQ spectral class members fail to exhibit this phenomenon, r…
First semi-empirical test of the white dwarf mass-radius relationship using a single white dwarf via astrometric microlensing
Peter McGill, Jay Anderson, Stefano Casertano +15
In November 2019, the nearby single, isolated DQ-type white dwarf LAWD 37 (WD 1142-645) aligned closely with a distant background source and caused an astrometric microlensing even…
Discovery of Beryllium in White Dwarfs Polluted by Planetesimal Accretion
Beth Klein, Alexandra E. Doyle, B. Zuckerman +5
The element beryllium is detected for the first time in white dwarf stars. This discovery in the spectra of two helium-atmosphere white dwarfs was made possible only because of the…
Serendipitous Discovery of Nine White Dwarfs With Gaseous Debris Disks
Carl Melis, B. Klein, A. E. Doyle +3
Optical spectroscopic observations of white dwarf stars selected from catalogs based on the Gaia DR2 database reveal nine new gaseous debris disks that orbit single white dwarf sta…
Compositions of Planetary Debris around Dusty White Dwarfs
Siyi Xu, Patrick Dufour, Beth Klein +5
The photospheres of some white dwarfs are "polluted" by accretion of material from their surrounding planetary debris. White dwarfs with dust disks are often heavily polluted and h…
The evolution of carbon-polluted white dwarfs at low effective temperatures
S. Blouin, P. Dufour
Taking advantage of the Gaia Data Release 2, recent studies have revisited the evolution of carbon-polluted white dwarfs (DQs) across a large range of effective temperatures. These…
A Massive Magnetic Helium Atmosphere White Dwarf Binary in a Young Star Cluster
Harvey B. Richer, Ronan M. Kerr, Jeremy Heyl +4
We have searched the Gaia DR2 catalogue for previously unknown hot white dwarfs in the direction of young open star clusters. The aim of this experiment was to try and extend the i…
On the Measurement of Fundamental Parameters of White Dwarfs in the Gaia Era
P. Bergeron, P. Dufour, G. Fontaine +5
We present a critical review of the determination of fundamental parameters of white dwarfs discovered by the Gaia mission. We first reinterpret color-magnitude and color-color dia…
Line Profiles of the Calcium I Resonance Line in Cool Metal-polluted White Dwarfs
S. Blouin, N. F. Allard, T. Leininger +2
Metal-polluted white dwarfs (DZ stars) are characterized by a helium-rich atmosphere contaminated by heavy elements traces originating from accreted rocky planetesimals. As a detai…
A New Generation of Cool White Dwarf Atmosphere Models. II. A DZ Star with Collision-Induced Absorption
Simon Blouin, Patrick Dufour, Nicole F. Allard +1
In the first paper of this series (Blouin et al. 2018), we presented our upgraded cool white dwarf atmosphere code. In this second paper, we use our new models to analyze SDSS J080…
Line shapes of the magnesium resonance lines in cool DZ white dwarf atmospheres
N. F. Allard, J. F. Kielkopf, S. Blouin +4
Line shapes of the magnesium resonance lines in white dwarf spectra are determined by the properties of magnesium atoms and the structure of the white dwarf atmosphere. Through the…
A New Generation of Cool White Dwarf Atmosphere Models. I. Theoretical Framework and Applications to DZ Stars
Simon Blouin, Patrick Dufour, Nicole F. Allard
The photospheres of the coolest helium-atmosphere white dwarfs are characterized by fluid-like densities. Under those conditions, standard approximations used in model atmosphere c…
Periodic optical variability and debris accretion in white dwarfs: a test for a causal connection
Na'ama Hallakoun, Dan Maoz, Eric Agol +9
Recent Kepler photometry has revealed that about half of white dwarfs (WDs) have periodic, low-level (~ 1e-4 - 1e-3), optical variations. Hubble Space Telescope (HST) ultraviolet s…
Pressure Distortion of the H-He Collision-Induced Absorption at the Photosphere of Cool White Dwarf Stars
Simon Blouin, Piotr M. Kowalski, Patrick Dufour
Collision-induced absorption (CIA) from molecular hydrogen is a dominant opacity source in the atmosphere of cool white dwarfs. It results in a significant flux depletion in the ne…
Magnetic White Dwarfs with Heavy Elements
François Hardy, Patrick Dufour, Stefan Jordan
Using our newly developed model atmosphere code appropriate for magnetic white dwarfs with metal lines in the Paschen-Back regime, we study various magnetic white dwarfs and explor…
A New Generation of Cool White Dwarf Atmosphere Models Using Ab Initio Calculations
Simon Blouin, Patrick Dufour, Piotr M. Kowalski
Due to their high photospheric density, cool helium-rich white dwarfs (particularly DZ, DQpec and ultracool) are often poorly described by current atmosphere models. As part of our…