The Most Massive White Dwarfs in the Solar Neighborhood

Abstract

We present an analysis of the most massive white dwarf candidates in the Montreal White Dwarf Database 100 pc sample. We identify 25 objects that would be more massive than $1.3M_{\odot }$ if they had pure H atmospheres and CO cores, including two outliers with unusually high photometric mass estimates near the Chandrasekhar limit. We provide follow-up spectroscopy of these two white dwarfs and show that they are indeed significantly below this limit. We expand our model calculations for CO core white dwarfs up to $M=1.334M_{\odot }$, which corresponds to the high-density limit of our equation-of-state tables, $\rho =10^9$ g cm${}^{-3}$. We find many objects close to this maximum mass of our CO core models. A significant fraction of ultramassive white dwarfs are predicted to form through binary mergers. Merger populations can reveal themselves through their kinematics, magnetism, or rapid rotation rates. We identify four outliers in transverse velocity, four likely magnetic white dwarfs (one of which is also an outlier in transverse velocity), and one with rapid rotation, indicating that at least 8 of the 25 ultramassive white dwarfs in our sample are likely merger products.

MNRAS, in press

References in corpus (13)

• On the Spectral Evolution of Hot White Dwarf Stars. I. A Detailed Model-Atmosphere Analysis of Hot White Dwarfs from SDSS DR12
• Binary Star Origin of High Field Magnetic White Dwarfs
• On the Spectral Evolution of Cool, Helium-Atmosphere White Dwarfs: Detailed Spectroscopic and Photometric Analysis of DZ Stars
• On the Measurement of Fundamental Parameters of White Dwarfs in the Gaia Era
• The 100 pc White Dwarf Sample in the SDSS Footprint
• $Gaia$ white dwarfs within 40 pc II: the volume-limited northern hemisphere sample
• Evolutionary Models for the Remnant of the Merger of Two Carbon-Oxygen Core White Dwarfs
• A New Generation of Cool White Dwarf Atmosphere Models. IV. Revisiting the Spectral Evolution of Cool White Dwarfs
• $\text{Gaia}$ white dwarfs within 40 pc I: spectroscopic observations of new candidates
• Merging Binary Stars and the magnetic white dwarfs
• An ultra-massive white dwarf with a mixed hydrogen-carbon atmosphere as a likely merger remnant
• Discovery of a hot ultramassive rapidly rotating DBA White Dwarf
• Intermediate-Mass Stars Become Magnetic White Dwarfs

Cited by in corpus (31)

• A catalogue of white dwarfs in Gaia EDR3
• Current challenges in the physics of white dwarf stars
• Triage of the Gaia DR3 astrometric orbits. I. A sample of binaries with probable compact companions
• An Isolated White Dwarf with a 70 second Spin Period
• The Merger Fraction of Ultramassive White Dwarfs
• White dwarf and subdwarf stars in the Sloan Digital Sky Survey Data Release 16
• Formation of ultra-massive carbon-oxygen white dwarfs from the merger of carbon-oxygen and helium white dwarf pairs
• Maximal Masses of White Dwarfs for Polytropes in $R^2$ Gravity and Theoretical Constraints
• The evolution of ultra-massive carbon oxygen white dwarfs
• Structure and evolution of ultra-massive white dwarfs in general relativity
• Near-Chandrasekhar-Mass Type Ia Supernovae from the Double-Degenerate Channel
• The Cooling of Massive White Dwarfs from Gaia EDR3
• Phase Separation in Ultramassive White Dwarfs
• The Ultramassive White Dwarfs of the Alpha Persei Cluster
• The Nearest Neutron Star Candidate in a Binary Revealed by Optical Time-domain Surveys
• WD J004917.14$-$252556.81, the Most Massive Pulsating White Dwarf
• Can we reveal the core-chemical composition of ultra-massive white dwarfs through their magnetic fields?
• Carbon-oxygen ultra-massive white dwarfs in general relativity
• The ubiquity of carbon dredge-up in hydrogen-deficient white dwarfs as revealed by GALEX
• Cooling Models for the Most Massive White Dwarfs
• The double white dwarf merger progenitors of SDSS J2211+1136 and ZTF J1901+1458
• A Crystallizing White Dwarf in a Sirius-Like Quadruple System
• FORECASTOR -- I. Finding Optics Requirements and Exposure times for the Cosmological Advanced Survey Telescope for Optical and UV Research mission
• Astrometric and photometric verification of faint blue white dwarfs in the Gaia catalogue of nearby stars
• The origin of ultramassive white dwarfs: hints from Gaia EDR3
• Merging White Dwarf Binaries Produce Type Ia Supernovae in Elliptical Galaxies
• General relativistic pulsations of ultra-massive ZZ Ceti stars
• A candidate giant planet companion to the massive, young white dwarf GALEX J071816.4+373139 informs the occurrence of giant planets orbiting B stars
• Search of nearby resolved neutron stars among optical sources
• A Lagrangian construction of rotating stars
• Charged anisotropic white dwarfs in $f\left(R,T\right)$ gravity