Lithium in white dwarfs from the Big Bang

IF 12.9 1区物理与天体物理 Q1 ASTRONOMY & ASTROPHYSICS

Nature Astronomy Pub Date : 2025-02-14 DOI:10.1038/s41550-025-02496-9

Bokyoung Kim

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Abstract

Some white dwarfs (WDs) show unique metallic features in their spectra, which are considered to originate from recently accreted planetesimals. Among these ‘metal-polluted’ WDs, only a few have lithium (Li) in their photosphere. Benjamin Kaiser and colleagues investigated five known Li-enhanced WDs and evaluated the physical parameters of the sample under different hypotheses for the Li enhancement. They concluded that the most likely scenario for three WDs is the accretion of primitive planetesimals containing Li from the Big Bang and Galactic nucleosynthesis (BBN).

The authors analysed the sample using consistent WD model atmospheres to estimate total ages of WDs and elemental abundances of accreted materials. Using these constraints, they ruled out another possible origin of the Li excess: accretion of icy exomoons containing light elements formed by high-energy proton bombardment. The low probability of exomoon accretion on WDs makes this hypothesis also highly unlikely to explain the Li enhancement in the other WDs. Instead, BBN seems the most plausible explanation for the Li enhancement in three WDs, as the abundances of accreted materials are compatible with those of primitive planetesimals expected from BBN evolution. For the remaining Li-enhanced WDs, stricter abundance measurements are required to confirm the origin of Li in SDSS J1330+6435, while no current hypotheses can explain the Li enhancement in the other (LHS 2534).

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来源期刊

Nature Astronomy Physics and Astronomy-Astronomy and Astrophysics

CiteScore

19.50

自引率

2.80%

发文量

252

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