Explaining the variability of WD 1145+017 with simulations of asteroid tidal disruption

Abstract

Post-main-sequence planetary science has been galvanised by the striking variability, depth and shape of the photometric transit curves due to objects orbiting white dwarf WD 1145+017, a star which also hosts a dusty debris disc and circumstellar gas, and displays strong metal atmospheric pollution. However, the physical properties of the likely asteroid which is discharging disintegrating fragments remain largely unconstrained from the observations. This process has not yet been modelled numerically. Here, we use the N-body code PKDGRAV to compute dissipation properties for asteroids of different spins, densities, masses, and eccentricities. We simulate both homogeneous and differentiated asteroids, for up to two years, and find that the disruption timescale is strongly dependent on density and eccentricity, but weakly dependent on mass and spin. We find that primarily rocky differentiated bodies with moderate (~3-4 g/cm^3) bulk densities on near-circular (e <~ 0.1) orbits can remain intact while occasionally shedding mass from their mantles. These results suggest that the asteroid orbiting WD 1145+017 is differentiated, resides just outside of the Roche radius for bulk density but just inside the Roche radius for mantle density, and is more akin physically to an asteroid like Vesta instead of one like Itokawa.

Accepted in MNRAS. Movies here!: http://www.star.bris.ac.uk/pcarter/WD1145_asteroid_disruption/

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Cited by in corpus (39)

• A planetesimal orbiting within the debris disc around a white dwarf star
• Numerical Simulations of Collisional Cascades at the Roche Limits of White Dwarf Stars
• Tidal disruption of planetary bodies by white dwarfs I: A hybrid SPH-analytical approach
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• Planetary Systems Around White Dwarfs
• Numerical Simulations of Gaseous Disks Generated from Collisional Cascades at the Roche Limits of White Dwarf Stars
• Tidal distortion and disruption of rubble-pile bodies revisited -- Soft-sphere discrete element analyses
• Horizontal spreading of planetary debris accreted by white dwarfs
• A dearth of small particles in the transiting material around the white dwarf WD 1145+017
• Modeling of the Variable Circumstellar Absorption Features of WD 1145+017
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• The lifetimes of planetary debris discs around white dwarfs
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• WD 1145+017: Optical Activity During 2016-2017 and Limits on the X-Ray Flux
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• Orbital relaxation and excitation of planets tidally interacting with white dwarfs
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• The dynamical history of the evaporating or disrupted ice giant planet around white dwarf WD J0914+1914
• Asynchronous accretion can mimic diverse white dwarf pollutants I: core and mantle fragments
• Shallow Ultraviolet Transits of WD 1145+017
• Magnetospherically-trapped dust and a possible model for the unusual transits at WD 1145+017
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• Survivability of radio-loud planetary cores orbiting white dwarfs
• The critical binary star separation for a planetary system origin of white dwarf pollution
• The Influence of Tidal Heating on the Habitability of Planets Orbiting White Dwarfs
• The entry geometry and velocity of planetary debris into the Roche sphere of a white dwarf
• Constraining planet formation around 6$M_{\odot }$-8$M_{\odot }$ stars
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