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

Manser, C. J.; Gänsicke, Boris T.; Eggl, Siegfried; Hollands, Mark; Izquierdo, P.; Koester, Detlev; Landstreet, John D.; Lyra, Wladimir; Marsh, Thomas R.; Meru, Farzana et al.
Bibliographical reference

Science, Volume 364, Issue 6435, pp. 66-69 (2019).

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Many white dwarf stars show signs of having accreted smaller bodies, implying that they may host planetary systems. A small number of these systems contain gaseous debris discs, visible through emission lines. We report a stable 123.4-minute periodic variation in the strength and shape of the Ca II emission line profiles originating from the debris disc around the white dwarf SDSS J122859.93+104032.9. We interpret this short-period signal as the signature of a solid-body planetesimal held together by its internal strength.