Astronomers find a planet reborn from its star's ashes

Amazing stuff!

"A team of astronomers ... have identified the first second-generation planet ever found around a white dwarf. While similar 'reborn' worlds have been suspected to exist around pulsars, this discovery shows that a second generation of planets can form around this much more common stellar remnant. ...

"Second-generation planets are worlds that form out of the material a star casts off as it dies. They're incredibly rare ...

white dwarf HS 0209+0832, whose atmosphere contains an unusual chemical signature. It showed unusually heavy elements including zinc, copper, and, most notably, niobium found at levels over 1,000 times higher than the Sun's. These are all elements created during the death of a star and notably the first-time niobium has been found in a white dwarf. ..."

From the abstract:

"Many white dwarfs accrete the debris of disrupted planetary bodies, detected in the form of metal enrichment in their atmospheres, dusty or gaseous circumstellar discs, and photometric transits from debris. The composition of accreted debris has been shown to be diverse yet overall closely resembles Solar System bodies.

Here we report the discovery of a white dwarf accreting material that is unlike any Solar System object. The atmosphere of HS 0209+0832 is strongly enriched in trans-iron elements including zinc, copper and niobium but depleted in the canonical rock-forming elements silicon and iron.

The composition of the accreted object is consistent with a candidate second-generation planet, formed from the stellar material ejected during the giant phase. The key abundance signature that differentiates it from a first-generation planet is the high enrichment of s-process elements. Photospheric helium and the absence of terrestrial rock-forming elements implies that the white dwarf is accreting from the escaped atmosphere of a photo-evaporating giant planet candidate.

This is further supported by the detection of a sinusoidal photometric period of 4.399 ± 0.026 days at an amplitude of 0.120% ± 0.018%, which we attribute to thermal emission phase variability from a planetary day–night cycle or a transiting cometary tail of an evaporating gas giant.

The discovery of this second-generation planet that is chemically distinct from first-generation material demonstrates that close-in planets around white dwarfs can form after the main sequence."

Astronomers find a world reborn from its star's ashes "University of Warwick astronomers have discovered the first example of a second-generation planet orbiting a white dwarf, a world that appears to have formed from the remains of the dead star it now orbits."

Discovery of a second-generation planet candidate accreting onto a white dwarf