Astronomers have made a significant discovery regarding the ancient white dwarf star LSPM J0207+3331, which continues to consume the remnants of its former planets billions of years after its stellar demise. Located 145 light-years away in the constellation Triangulum, this white dwarf, slightly larger than the Sun, was closely examined using the W. M. Keck telescopes in Hawaii.
A research team led by University of Montréal PhD student Érika Le Bourdais found that this aged stellar remnant remains active in absorbing planetary debris, providing valuable insights into the evolution of planetary systems and the fate of exoplanets surrounding dying stars. Le Bourdais noted that the continued accretion of planetary material three billion years post-white dwarf formation challenges existing understandings of stellar system evolution.
Discovered in 2019 during NASA”s Backyard Worlds: Planet 9 project, LSPM J0207+3331 was identified by a citizen scientist. Astronomers quickly recognized its unusually low temperature, a characteristic of aging white dwarfs. Previous research by John Debes of the Space Telescope Science Institute indicated the presence of an infrared flare, hinting at a surrounding debris disk.
Upon analyzing the star”s light spectrum, Le Bourdais and her team found compelling evidence of planetary material in the star”s atmosphere. According to co-author Patrick Dufour, a professor at the University of Montréal, studying the composition of exoplanets through white dwarfs is one of the few direct methods available. The gravitational pull of the star can tear apart nearby planet fragments, leaving behind chemical signatures.
In this case, despite the star”s dense atmosphere, which is primarily composed of hydrogen, the team identified thirteen elements, including magnesium, iron, nickel, and silicon. These elements suggest the existence of a rocky, Earth-like planet with a metallic core and rocky mantle in its past.
The origin of this ancient debris remains a mystery. Scientists propose that gravitational interactions with long-lived giant planets may have destabilized the system, or that a passing star could have disturbed the debris field. Future observations from the James Webb Space Telescope or data from the Gaia mission may help clarify which scenario is most plausible.
