A team of UK-based researchers says it has found the first evidence of a planet that may have formed not at a star’s birth, like Earth did, but from the wreckage of a star’s death.
The findings, published last week in Nature Astronomy, center on a white dwarf called HS 0209+0832, located roughly 270 light years from Earth in the constellation Cetus. Scientists re-examined data pulled from NASA’s Hubble Telescope back in 1999 and found about 100 unidentified chemical features surrounding the dead star.
Among those signatures were heavy elements like niobium, substances that are not found in ordinary star systems. Researchers say elements like these can only form under the extreme conditions present briefly inside a dying star — meaning something out there appears to have formed from the star’s own death throes, and the star has been feeding off it.
“These heavy elements can only be synthesized in the exotic conditions that briefly emerge inside dying stars,” said Dr. Nicholas Stone, a theoretical astrophysicist at the University of Wisconsin-Madison and co-author of the study, in remarks to Sci.News.
The team also detected a brightness cycle repeating roughly every 4.4 days — consistent with day-and-night temperature swings on a large planet orbiting extremely close to its star, at just 0.04 Astronomical Units. That’s about 25 times closer than Earth sits to the sun.
If such a planet exists, it appears to be losing atmosphere to its dying host star. But researchers are not writing it off.
“If the second-generation planet is there, I think it is likely to survive,” said Jamie Williams, an astronomer at the University of Warwick and study co-author.
Williams said that once the white dwarf finishes cooling, it will settle into a stable temperature — potentially keeping a close-orbiting rocky planet in a habitable zone for millions of years. He told Universe Today that steady heat output could allow such a world to remain habitable for tens of billions of years, dwarfing Earth’s own timeline. Earth is expected to be destroyed or engulfed when the sun dies in roughly 5 billion years.
No second-generation planet has ever been confirmed before. Researchers say the HS 0209+0832 findings still require verification, and more study is needed before anyone can say for certain that a planet formed there at all.
