A planetesimal orbiting within the debris disc around a white dwarf star

<jats:title>A low-mass planet around a white dwarf</jats:title>
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Numerous exoplanets have been detected around Sun-like stars. These stars end their lives as white dwarfs, which should inherit any surviving planetary systems. Manser
<jats:italic>et al.</jats:italic>
found periodic shifts in emission lines from a disc of gas orbiting around a white dwarf (see the Perspective by Fossati). They used numerical simulations to show that the most likely explanation for the spectral shifts is a low-mass planet orbiting within the disc. The planet must be unusually small and dense to avoid being ripped apart by tidal forces. The authors speculate that it may be the leftover core of a planet whose outer layers have been removed.
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<jats:italic>Science</jats:italic>
, this issue p.
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; see also p.
<jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6435" page="25" related-article-type="in-this-issue" vol="364" xlink:href="10.1126/science.aax0051">25</jats:related-article>
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