Lithium pollution of a white dwarf records the accretion of an extrasolar planetesimal

Abstract

Tidal disruption and subsequent accretion of planetesimals by white dwarfs can reveal the elemental abundances of rocky bodies in exoplanetary systems. Those abundances provide information on the composition of the nebula from which the systems formed, analogous to how meteorite abundances inform our understanding of the early Solar System. We report the detection of Li, Na, K and Ca in the atmosphere of the white dwarf Gaia DR2 4353607450860305024, which we ascribe to accretion of a planetesimal. Using model atmospheres, we determine abundance ratios of these elements, and with the exception of Li, they are consistent with meteoritic values in the Solar System. We compare the measured Li abundance to measurements in old stars and to expectations from Big Bang nucleosynthesis.

Sub 30Jun2020;acc 4Dec; pub 17Dec2020; This manuscript has been accepted for publication in Science. This version has not undergone final editing. Please refer to the complete version of record at http://www.sciencemag.org/. The manuscript may not be reproduced or used in any manner that does not fall within the fair use provisions of the Copyright Act without the prior, written permission of AAAS

References in corpus (17)

• The Gaia mission
• The frequency of planetary debris around young white dwarfs
• Stellar Abundances in the Solar Neighborhood: The Hypatia Catalog
• On the Spectral Evolution of Cool, Helium-Atmosphere White Dwarfs: Detailed Spectroscopic and Photometric Analysis of DZ Stars
• Standard big bang nucleosynthesis and primordial CNO Abundances after Planck
• The 100 pc White Dwarf Sample in the SDSS Footprint
• The Elemental Abundances (with Uncertainties) of the Most Earth-like Planet
• Flux calibration of medium-resolution spectra from 300 nm to 2500 nm: Model reference spectra and telluric correction
• Cool DZ white dwarfs I: Identification and spectral analysis
• Compositions of Planetary Debris around Dusty White Dwarfs
• Are exoplanetesimals differentiated?
• Characterizing the High-Velocity Stars of RAVE: The Discovery of a Metal-Rich Halo Star Born in the Galactic Disk
• Random Forest identification of the thin disk, thick disk and halo Gaia-DR2 white dwarf population
• Ultracool white dwarfs and the age of the Galactic disc
• Pressure Distortion of the H${}_2$-He Collision-Induced Absorption at the Photosphere of Cool White Dwarf Stars
• A New Generation of Cool White Dwarf Atmosphere Models. III. WD J2356$-$209: Accretion of a Planetesimal with an Unusual Composition
• Line Profiles of the Calcium I Resonance Line in Cool Metal-polluted White Dwarfs

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