Like a Mythical Phoenix, This Planet May Have Risen From the Ashes of a Dead Star

In 1999, the Hubble Space Telescope turned its gaze upon a white dwarf—a dense remnant of a star—and detected around 100 mysterious chemical features in its atmosphere. More than two decades later, astronomers have now taken another look at the enigmatic data and realized that it points to the presence of a very unusual cosmic body. In a study published this week in Nature Astronomy, researchers reveal the possibility that a “second-generation” planet is orbiting the white dwarf.

In other words, this world might have been born from the scraps of the dead star. If these findings are confirmed, the planet would be the first of its kind known to researchers and could provide insight into a potential future for our own solar system. After a small star runs out of nuclear fuel, it sheds its wrapping of gas and dust, leaving behind a core known as a white dwarf.

The team suggests that a planet orbiting the white dwarf HS 0209+0832 came together from the accretion of its lost gas and dust, like a sort of astronomical phoenix. White dwarfs consist of very tightly packed matter. Just one teaspoon of this ultra-dense material would, on Earth, weigh as much as an elephant.

When Williams returned to Hubble’s 1999 data, he noticed that many of the mysterious chemical features could be niobium, a kind of metal used in jewelry and medical imaging devices. As opposed to many common elements, niobium is too heavy to be created by the fusion reactions that happen within a star. Instead, niobium forms “in the exotic conditions that briefly emerge inside dying stars,” study co-author Nicholas Stone, a theoretical astrophysicist at the University of Wisconsin–Madison, says in a NASA statement.

As such, niobium is a marker for stellar death. And while this star’s death throes ejected material, including niobium, out to space, part of it formed into a gas giant planet, the researchers hypothesize. It’s hard for planets to come together in these conditions, however, which partly explains why second-generation planets are exceptionally rare, Williams adds in a university statement.

The gravity of another star was probably necessary to shape the expelled material into a planet-birthing disk. Using NASA’s TESS satellite, the team recognized periodic changes in HS 0209+0832’s brightness that point to an orbiting planet passing in front of it. According to their estimations, this candidate planet—it’s not yet confirmed—is a gas giant with a close orbit of around 3.7 million miles.