Astronomers Detect Potential ‘Second Generation’ Planet Around Dying Stellar White Dwarf

Potential ‘Second generation’ planet detection around a dying stellar white dwarf opens a whole new chapter of exoplanetary science. Identified as HS 0209+0832, this particular white dwarf’s unusual atmospheric makeup is what first prompted the University of Warwick-led team to reanalyze 25-year-old data from NASA’s Hubble Space Telescope.

Located some 270 light years away in the southern constellation of Cetus, HS 0209+0832 has an atmosphere that includes zinc, copper, aluminum, silicon, and titanium. K. -led team found at levels more than 1000 times that of our Sun.

The team noted in a paper appearing in the journal Nature Astronomy that they think the most likely explanation is that the white dwarf, HS 0209+0832, is feeding off a newly formed, second-generation giant planet --- one that condensed out of a new disc of material formed during.

We now know that elements like niobium can be used as signatures of accretion from second generation planets, Jamie Williams, the Nature Astronomy paper’s lead author and a doctoral candidate in physics at the University of Warwick in the U. K, told me via email. So, observing more hot white dwarfs with Hubble could discover more candidates, Williams told me.

Using archival data from Hubble and the FUSE (Far Ultraviolet Spectroscopic Explorer) telescope as well as NASA’s TESS (Transiting Exoplanet Survey Satellite), the researches found that the putative planet is orbiting HS 0209+0832 on the incredibly short orbit of only 4.4 days. For decades, astrophysicists have argued over whether it would be possible for a planet to form from the detritus of a stellar remnant, and this detection marks the first time that has happened.

But the amount Hubble found in the HS 0209+0832 system points to a planet forming not from a star’s birth, but from the material ejected as it dies, Williams notes.

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