Cooling Models for the Most Massive White Dwarfs

Abstract

We present a set of ultramassive white dwarf models, focused on masses above $1.3M_{\odot }$. Given the uncertainties about the formation and compositions of such objects, we construct parameterized model sequences, guided by evolutionary calculations including both single star and double white dwarf merger formation channels. We demonstrate that the cooling of objects with central densities in excess of $10^9\mathrm{g}\mathrm{c}{\mathrm{m}}^{-3}$ is dominated by neutrino cooling via the Urca process in the first $\approx 100$ Myr after formation. Our models indicate that the recently discovered ultramassive white dwarf ZTF J190132.9+145808.7 is likely to have experienced this Urca-dominated cooling regime. We also show that the high densities imply that diffusion is unlikely to significantly alter the core compositions of these objects before they crystallize.

9 pages, 6 figures; Accepted to ApJ

References in corpus (15)

• Modules for Experiments in Stellar Astrophysics (MESA)
• Modules for Experiments in Stellar Astrophysics (MESA): Pulsating Variable Stars, Rotation, Convective Boundaries, and Energy Conservation
• Updated Electron-Conduction Opacities: The Impact on Low-Mass Stellar Models
• On the Spectral Evolution of Hot White Dwarf Stars. I. A Detailed Model-Atmosphere Analysis of Hot White Dwarfs from SDSS DR12
• Fusion reactions in multicomponent dense matter
• A highly magnetised and rapidly rotating white dwarf as small as the Moon
• Evolutionary Models for the Remnant of the Merger of Two Carbon-Oxygen Core White Dwarfs
• New Conductive Opacities for White Dwarf Envelopes
• ${}^{22}$Ne Phase Separation As A Solution To The Ultramassive White Dwarf Cooling Anomaly
• Diffusion of Neon in White Dwarf Stars
• The formation of ultra-massive carbon-oxygen core white dwarfs and their evolutionary and pulsational properties
• The Most Massive White Dwarfs in the Solar Neighborhood
• The Importance of Urca-process Cooling in Accreting ONe White Dwarfs
• The neutrino emission due to plasmon decay and neutrino luminosity of white dwarfs
• Discovery of a hot ultramassive rapidly rotating DBA White Dwarf

Cited by in corpus (3)

• The evolution of ultra-massive carbon oxygen white dwarfs
• Phase Separation in Ultramassive White Dwarfs
• Accurate Diffusion Coefficients for Dense White Dwarf Plasma Mixtures