Astronomers re-examining archived Hubble Space Telescope data from the white dwarf HS 0209+0832 report a possible second-generation planet, a world that would have formed from material cast off by a dying star rather than from the leftovers of its birth. The study was published Monday in Nature Astronomy, according to NASA.

Hubble first observed the star in 1999, when the data contained roughly 100 unidentified chemical features. Lead author Jamie Williams of the University of Warwick returned to those records with an updated chemical database and found that niobium matched many of the mystery features. The team confirmed the finding with data from NASA's retired FUSE mission; TESS observed the white dwarf for four months and detected periodic brightness variations indicating a planet orbits at about 3.7 million miles (6 million kilometers), much closer than Mercury orbits the Sun.

The team estimates the candidate is a gas giant about the size of Jupiter that is rapidly losing atmosphere to the hot white dwarf. Co-author Boris Gaensicke said niobium had not been reported in any other white dwarf analyzed to date. Williams said further Hubble work is planned over the next several years to study how such planets form and evolve.