A deceased stellar core situated roughly 145 light-years from Earth is far from lying still. Astronomers have found that this white dwarf, the remnant of a medium-sized star that has depleted its nuclear fuel, has ingested a rocky planet from its previous system. Notably, this white dwarf has been lifeless for nearly 3 billion years. The stellar remnant, referred to as LSPM J0207+3331, indicates that even ancient planetary systems continue to be dynamic long after their parent stars have perished, challenging conventional beliefs about the concluding phases of a star, including those of our sun.
John Debes, a co-investigator of the research at the Space Telescope Science Institute in Baltimore, stated that a deceased star that is no longer undergoing fusion still affects its environment. As its temperature declines, its gravitational force persists. “White dwarfs are genuinely like the ember remnants after a blaze,” Debes remarked. “For billions of years, (the remnant) continues to emit light and radiation, which undoubtedly have an impact.”
In spite of the advanced age of the white dwarf, it harbors a debris disk filled with heavy elements. This substance implies that a rocky object, such as a dwarf planet, moon, or asteroid, was recently attracted and disintegrated, as per the study published in The Astrophysical Journal Letters. Utilizing the W. M. Keck Observatory in Hawaii, scientists identified 13 distinct chemical elements in the atmosphere of the white dwarf, including iron, nickel, silicon, and calcium, which are out of place. The chemical composition resembles that of Earth, albeit with a slightly higher concentration of iron and nickel. The results suggest that the star devoured a small entity approximately 120 miles across with a substantial metallic core, potentially larger relative to Earth’s.
The most plausible scenario is that a disturbance, possibly a gravitational pull from another planet, displaced the small entity from its orbit, compelling it to spiral towards the white dwarf. Patrick Dufour, a co-author from the Université de Montréal, noted that it is rare to find such a significant amount of rocky material surrounding an old white dwarf, particularly one with a hydrogen-rich atmosphere. Almost all white dwarfs displaying this type of contamination had helium-rich atmospheres, where heavy elements are more easily detected.
The latest findings suggest that even cool, hydrogen-rich white dwarfs, which comprise the majority of known white dwarfs, can accumulate and consume planetary debris for billions of years. Scientists suspect that concealed worlds the size of Jupiter may be orbiting the white dwarf, perturbing the system from a distance. These colossal exoplanets would be challenging to observe directly due to their cold and remote nature, but upcoming observations from telescopes such as the European Space Agency’s Gaia and NASA’s James Webb Space Telescope could aim to locate them.
Researchers are keen on LSPM J0207+3331 because it was once a star akin to our own. Investigating it may yield valuable information regarding the final chapter for our solar system, approximately 5 billion years following the sun’s demise. “We are undeniably witnessing that planetary systems remain active and have much to reveal to us at all life phases of a star,” Debes said. “It opens the intriguing prospect that our solar system could have a vibrant and engaging existence even after our sun transforms into a white dwarf.”