Warwick astronomers identify a possible planet formed from a dead star’s remains
A University of Warwick-led team says the white dwarf HS 0209+0832 may be orbited by the first second-generation planet identified around a white dwarf. Its atmosphere contains niobium at more than 1,000 times the Sun’s level, and TESS data show a faint signal repeating every 4.4 days. If confirmed, the candidate would show that planets may form from material shed as stars die.
Bottom line — Confirmation would give astronomers a new chemical signature to search for around other white dwarfs.
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The team’s paper in Nature Astronomy describes the object as a planet candidate; the interpretation is not yet confirmed.
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Researchers say the star’s atmosphere also contains unusually high levels of zinc and copper, alongside niobium.
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Nicholas Stone of the University of Wisconsin–Madison links the elements to the s-process, which builds heavy elements inside dying stars.
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Jamie Williams and colleagues say a companion star may have pulled ejected material into a disc where a new planet could form.
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The 4.4-day signal is consistent with a Jupiter-sized gas giant in a close orbit, according to the team.
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The researchers expect radiation from the white dwarf to strip the planet’s outer atmosphere, with material falling onto the star.