Astronomers reexamining 1999 Hubble observations of the white dwarf HS 0209+0832 have found an unusual chemical signature. A study published in Nature Astronomy reports high levels of niobium, an element heavier than iron that can only form in the exotic conditions of dying stars. Lead author Jamie Williams of the University of Warwick identified the signature after returning to the archival data with an updated chemical database, resolving features that had gone unexplained for decades.
The team proposes that the niobium traces material expelled when the star died, and that some of this enriched matter later assembled into a gas giant. NASA's TESS mission adds supporting evidence: four months of brightness monitoring revealed repeating variations consistent with a Jupiter-sized planet orbiting about 3.7 million miles from the star, far closer than Mercury is to the Sun. Because the white dwarf is still extremely hot, it may be stripping the planet's atmosphere, creating a comet-like tail and feeding material back onto the star.
Co-author Nicholas Stone of the University of Wisconsin–Madison notes that heavy elements like niobium are not produced by thermonuclear fusion in stellar cores, but only during stellar death throes. Co-author Boris Gaensicke, also at Warwick, said niobium had not been reported in any other white dwarf analyzed to date. Williams added that if the planet exists, it is likely to survive as the white dwarf cools, potentially remaining in a stable habitable zone for millions of years.