Can tidal evolution lead to close-in planetary bodies around white dwarfs II: volcanism and transits

TL;DR

This paper explores how tidal interactions can induce volcanism in planetesimals around white dwarfs, potentially explaining observed transits and dust production, and highlights a mechanism for close-in planetary bodies formation.

Contribution

It introduces a new model linking tidal interactions to volcanism and dust production in planetesimals near white dwarfs, explaining observed transits and debris.

Findings

Tidal interactions can induce volcanism in planetesimals within specific orbital parameters.

Volcanic ejecta may be responsible for observed optical transits around white dwarfs.

Tidal-induced volcanism occurs over a wide range of orbital configurations.

Abstract

Planetary material accreted by white dwarfs provides unique insights regarding exoplanetary composition. The evolutionary pathways of planetary bodies around white dwarfs are crucial to understanding the presence of close-in planetary material, observed in the form of pollutants in the atmospheres of white dwarfs and planetary material transiting white dwarfs. Periodic transits around white dwarfs potentially reveal the existence of close-in planetary bodies undergoing dust production. Tidal interactions can bring planetesimals that have been gravitationally perturbed onto long-period highly eccentric orbits around white dwarfs towards shorter orbital periods and smaller eccentricities. Tidal interactions may also induce melting and volcanism in these planetesimals, potentially being a mechanism for dust and debris production, the result of which may be seen in transit. Tidally induced volcanism may be triggered in a wide parameter space: for a 100km-sized rocky planetesimals perturbed to a pericentre distance $\lesssim$ 0.01AU ($\gtrsim$ twice its Roche limit), both on long-period (~ 100day) highly eccentric orbits and short-period (~ 10hr) near circular orbits. We comment on the potential link between the resultant volcanic ejecta and observed optical transits.