Accretion of a Terrestrial-Like Minor Planet by a White Dwarf

TL;DR

This paper characterizes a white dwarf with a dusty debris disk, revealing it has accreted a differentiated, Earth-like parent body, providing insights into planetary material around evolved stars.

Contribution

It presents detailed optical and infrared observations of a polluted white dwarf, identifying new elements and suggesting the accretion of an Earth-like planetary body.

Findings

Detection of chromium and manganese in the white dwarf's atmosphere.

The accreted material's composition resembles Earth's crust and mantle.

Evidence for processes like irradiation and stellar wind interaction affecting planetary bodies.

Abstract

We present optical and infrared characterization of the polluted DAZ white dwarf GALEX J193156.8+011745. Imaging and spectroscopy from the ultraviolet to the thermal infrared indicates that the white dwarf hosts excess infrared emission consistent with the presence of an orbiting dusty debris disk. In addition to the five elements previously identified, our optical echelle spectroscopy reveals chromium and manganese and enables restrictive upper limits on several other elements. Synthesis of all detections and upper limits suggests that the white dwarf has accreted a differentiated parent body. We compare the inferred bulk elemental composition of the accreted parent body to expectations for the bulk composition of an Earth-like planet stripped of its crust and mantle and find relatively good agreement. At least two processes could be important in shaping the final bulk elemental composition of rocky bodies during the late phases of stellar evolution: irradiation and interaction with the dense stellar wind.