Six White Dwarfs with Circumstellar Silicates

TL;DR

This study uses Spitzer spectra to identify silicate dust around six white dwarfs, suggesting asteroid disruption as the dust source and indicating rocky planet formation from carbon-poor materials.

Contribution

It provides new observational evidence linking circumstellar silicates to asteroid disruption around white dwarfs, highlighting the composition of exoplanetary debris.

Findings

Silicate emission detected around six white dwarfs.

Dust likely produced by tidal disruption of asteroids.

Absence of PAH features suggests carbon-poor rocky planet formation.

Abstract

Spitzer Space Telescope spectra reveal 10 micron silicate emission from circumstellar dust orbiting six externally-polluted white dwarfs. Micron-size glasses with an olivine stoichiometry can account for the distinctively broad wings that extend to 12 microns; these particles likely are produced by tidal-disruption of asteroids. The absence of infrared PAH features is consistent with a scenario where extrasolar rocky planets are assembled from carbon-poor solids.