zyntrax

HS 0209+0832 is a white dwarf: a burned-out star, 35,000 K, five million years dead. Its air should be clean hydrogen. Instead it carries trans-iron metals, zinc, copper and niobium, and almost no silicon or iron.

The mix matches nothing in the Solar System. The team's read: the star is eating the remains of a second-generation planet, condensed from its own shed envelope, now boiled back off by ultraviolet light.

The fingerprint is niobium, an s-process element dying AGB stars forge, so material from their ejecta should be niobium-rich. The team pinned it from 57 Nb IV lines and five Nb III lines; 33 other metal-rich white dwarfs showed none.

No image, no transit depth, no radial-velocity detection. The planet is the interpretation. The chemistry is what's in hand.

TESS adds a 4.399 +/– 0.026 day signal, 0.120 +/– 0.018 percent deep: a hot planet's day-night glow, or a comet-like tail of escaping gas crossing the star. Both fit.

Caveats: a candidate, not a detected planet; the period is ambiguous; and AGB models, which predict strontium above niobium, don't fit either.

Williams, Gansicke, Stone et al., arXiv 2610.07161. Accepted by Nature Astronomy.