Scientists detect first 'second-generation' planet
Astronomers have identified what may be the first “second-generation” planet, formed from the remnants of a star after the end of its life and its transformation into a white dwarf, in a discovery that could open a new avenue for understanding planetary formation.
The planet, which remains only a candidate, is believed to be a gas giant orbiting the white dwarf HS 0209+0832, located approximately 270 light-years from Earth, according to a study published in the journal Nature Astronomy.
Researchers analyzed data from the Hubble Space Telescope and other observatories, finding unusual traces of heavy elements, notably niobium, on the surface of the white dwarf.
Scientists believe these elements originated from planetary material falling onto the white dwarf after the star’s radiation stripped the atmosphere of a nearby planet.
Jamie Williams, the study’s lead researcher from the University of Warwick in the UK, said that the detection of niobium for the first time in a white dwarf suggests that the material surrounding the star may have formed from “stellar ash” during the star’s death.
Data from NASA’s Transiting Exoplanet Survey Satellite (TESS) supported the planet hypothesis, revealing a faint, recurring dip in the system’s brightness every 4.4 days, consistent with a massive body orbiting the white dwarf.
However, researchers emphasize that this evidence is not yet sufficient to confirm the discovery of a planet.
Williams stated, “It is not a confirmed planet. It is merely a candidate at this stage.”
This hypothesis differs from planets that survived the death of their host stars; some planets that formed alongside the original star can remain if their orbits were distant enough from the star during its transition to a white dwarf.
In contrast, the potential planet in this case is believed to have formed after the star’s death from the material it left behind, classifying it as a “second-generation planet.”
When a Sun-like star approaches the end of its life, it expands into a red giant before shedding its outer layers, leaving behind a hot, dense core known as a white dwarf.
Researchers suggest that the dust and gas produced during this process may have formed a disk around the white dwarf, with its material gradually accumulating to form a new planet.
However, this process may require the presence of another celestial body, such as a small star or brown dwarf, interacting with the star during the red giant phase, which could help retain some of the material in a disk orbiting the remaining core.
