Astronomers Find Evidence of 'Second-Generation' Planet Forming Around Dying Star

Astronomers have discovered the first potential evidence of a "second-generation" planet forming from the remnants of a dying star. The possible exoplanet, estimated to be roughly the size of Jupiter, appears to have coalesced from gases cast off by the white dwarf star HS 0209+0832, located approximately 270 light-years from Earth in the constellation Cetus.

Researchers re-examined data originally collected by NASA's Hubble Telescope in 1999. They identified about 100 unidentified chemical features around the dense, dead star. According to a study published in Nature Astronomy, the abundance of certain elements heavier than iron, such as niobium, suggests that a planet had formed and was interacting with the star's ejected material.

Unlike planets in our solar system, which form from the initial disk of gas and dust surrounding a young star, this potential planet appears to have formed from stellar debris shed by the white dwarf as it aged. "These heavy elements can only be synthesized in the exotic conditions that briefly emerge inside dying stars," Dr. Nicholas Stone, a theoretical astrophysicist at the University of Wisconsin – Madison and a co-author of the study, told Sci.News.

The team also observed a repeating brightness cycle of approximately 4.4 days. This variation could be attributed to the day and night temperature differences on a massive planet orbiting extremely close to its star, at a distance of about 0.04 Astronomical Units—25 times closer than Earth is to the Sun.

If the planet exists, it is currently losing atmosphere. However, researchers are optimistic about its long-term prospects. "If the second-generation planet is there, I think it is likely to survive," said University of Warwick astronomer Jamie Williams, a co-author of the study, as quoted by Universe Today. "Eventually the white dwarf will cool and then maintain a consistent temperature, with the planet in its stable habitable zone for millions of years."

Williams noted that a planet in such a stable, long-term habitable zone could potentially remain viable for tens of billions of years, far exceeding the estimated lifespan of Earth before it is engulfed by the Sun in approximately 5 billion years.

This discovery, if officially verified, would mark the first observation of a second-generation planet. Further research is needed to confirm its existence.