Magnetic dynamos in white dwarfs -- II. Relating magnetism and pollution

Abstract

We investigate whether the recently suggested rotation and crystallization driven dynamo can explain the apparent increase of magnetism in old metal polluted white dwarfs. We find that the effective temperature distribution of polluted magnetic white dwarfs is in agreement with most/all of them having a crystallizing core and increased rotational velocities are expected due to accretion of planetary material which is evidenced by the metal absorption lines. We conclude that a rotation and crystallization driven dynamo offers not only an explanation for the different occurrence rates of strongly magnetic white dwarfs in close binaries, but also for the high incidence of weaker magnetic fields in old metal polluted white dwarfs.

Accepted for publication in MNRAS Letters

References in corpus (22)

• The frequency of planetary debris around young white dwarfs
• A gaseous metal disk around a white dwarf
• On the Spectral Evolution of Hot White Dwarf Stars. I. A Detailed Model-Atmosphere Analysis of Hot White Dwarfs from SDSS DR12
• White Dwarf Rotation as a Function of Mass and a Dichotomy of Mode Linewidths: Kepler Observations of 27 Pulsating DA White Dwarfs Through K2 Campaign 8
• A planetesimal orbiting within the debris disc around a white dwarf star
• Accretion of a giant planet onto a white dwarf
• $Gaia$ white dwarfs within 40 pc II: the volume-limited northern hemisphere sample
• Detectable close-in planets around white dwarfs through late unpacking
• A common origin of magnetism from planets to white dwarfs
• Cool DZ white dwarfs I: Identification and spectral analysis
• $\text{Gaia}$ white dwarfs within 40 pc I: spectroscopic observations of new candidates
• Magnetic Prandtl number dependence of kinetic to magnetic dissipation ratio
• The Solar Neighborhood. XXXIX. Parallax Results from the CTIOPI and NOFS Programs: 50 New Members of the 25 Parsec White Dwarf Sample
• The incidence of magnetic fields in cool DZ white dwarfs
• WD 1856 b: a close giant planet around a white dwarf that could have survived a common-envelope phase
• Toward Precision Cosmochronology: A New C/O Phase Diagram for White Dwarfs
• Magnetism, X-rays, and Accretion Rates in WD 1145+017 and other Polluted White Dwarf Systems
• Do instabilities in high-multiplicity systems explain the existence of close-in white dwarf planets?
• How Jupiters save or destroy inner Neptunes around evolved stars
• Single magnetic white dwarfs with Balmer emission lines: A small class with consistent physical characteristics as possible signposts for close-in planetary companions
• A test of the planet-star unipolar inductor for magnetic white dwarfs
• The nearby magnetic cool DZ white dwarf PM J08186-3110

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