This artist’s illustration shows a 3-billion-year-old white dwarf star accreting material from the remnants of its former planetary system. Gravitational instabilities caused a surviving planet to spiral inward and disintegrate under intense tidal forces, forming a debris disk. Spectroscopic analysis of the white dwarf’s atmosphere revealed the presence of this planetary debris. Credits/Artwork: NASA, ESA, Joseph Olmsted (STScI)
Astronomers have identified a rare, ancient planetary system still being actively consumed by its central white dwarf star, LSPM J0207+3331, which is located 145 light-years from Earth. This system hosts the oldest and most metal-rich debris disk ever observed around a hydrogen-rich white dwarf, raising new questions about the long-term stability of planetary systems billions of years after stellar death.
“This discovery challenges our understanding of planetary system evolution,” said lead author Érika Le Bourdais of the Trottier Institute for Research on Exoplanets at Université de Montréal. “Ongoing accretion at this stage suggests white dwarfs may also retain planetary remnants still undergoing dynamical changes.”
Spectroscopic data from the W. M. Keck Observatory on Maunakea in Hawaiʻi revealed the white dwarf’s atmosphere is polluted with 13 chemical elements, an evidence of a rocky body at least 120 miles (200 kilometers) wide that was torn apart by the star’s gravity. “The amount of rocky material is unusually high for a white dwarf of this age,” noted co-author Patrick Dufour, also of Université de Montréal.
Hydrogen-rich atmospheres around white dwarfs typically mask such elemental signatures, making this detection especially significant. “Something clearly disturbed this system long after the star’s death,” said co-investigator John Debes of the Space Telescope Science Institute in Baltimore, Maryland. “There’s still a reservoir of material capable of polluting the white dwarf, even after billions of years.”
Astronomers have identified a rare, ancient planetary system still being actively consumed by its central white dwarf star, LSPM J0207+3331, which is located 145 light-years from Earth. This system hosts the oldest and most metal-rich debris disk ever observed around a hydrogen-rich white dwarf, raising new questions about the long-term stability of planetary systems billions of years after stellar death.
“This discovery challenges our understanding of planetary system evolution,” said lead author Érika Le Bourdais of the Trottier Institute for Research on Exoplanets at Université de Montréal. “Ongoing accretion at this stage suggests white dwarfs may also retain planetary remnants still undergoing dynamical changes.”
Spectroscopic data from the W. M. Keck Observatory on Maunakea in Hawaiʻi revealed the white dwarf’s atmosphere is polluted with 13 chemical elements, an evidence of a rocky body at least 120 miles (200 kilometers) wide that was torn apart by the star’s gravity. “The amount of rocky material is unusually high for a white dwarf of this age,” noted co-author Patrick Dufour, also of Université de Montréal.
Hydrogen-rich atmospheres around white dwarfs typically mask such elemental signatures, making this detection especially significant. “Something clearly disturbed this system long after the star’s death,” said co-investigator John Debes of the Space Telescope Science Institute in Baltimore, Maryland. “There’s still a reservoir of material capable of polluting the white dwarf, even after billions of years.”
Delayed planetary instability
Nearly half of all polluted white dwarfs show signs of accreting heavy elements, indicating their planetary systems have been dynamically disturbed. In the case of LSPM J0207+3331, a recent perturbation— within the last few million years—probably sent a rocky planet spiraling inward. “This suggests tidal disruption and accretion mechanisms remain active long after the main-sequence phase of a star’s life,” said Debes. “Mass loss during stellar evolution can destabilize orbits, affecting planets, comets, and asteroids.”
The system may exemplify delayed instability, where multi-planet interactions gradually destabilize orbits over billions of years. “This could point to long-term dynamical processes we don’t yet fully understand,” Debes added.
The system may exemplify delayed instability, where multi-planet interactions gradually destabilize orbits over billions of years. “This could point to long-term dynamical processes we don’t yet fully understand,” Debes added.
Searching for Outer Planets
Astronomers are now investigating what may have triggered the disruption. Surviving Jupiter-sized planets could be responsible but are difficult to detect due to their separation from the white dwarf and low temperatures. Data from ESA’s Gaia space telescope may be sensitive enough to detect such planets through their gravitational influence on the white dwarf.
NASA’s James Webb Space Telescope could also provide insights by taking infrared observations of the system for signs of outer planets. “Future observations may help distinguish between a planetary shakeup or the gravitational effect of a stellar close encounter with the white dwarf,” said Debes.
NASA’s James Webb Space Telescope could also provide insights by taking infrared observations of the system for signs of outer planets. “Future observations may help distinguish between a planetary shakeup or the gravitational effect of a stellar close encounter with the white dwarf,” said Debes.
These results published today in The Astrophysical Journal Letters.
The Space Telescope Science Institute is expanding the frontiers of space astronomy by hosting the science operations center of the Hubble Space Telescope, the science and mission operations centers for the James Webb Space Telescope, and the science operations center for the Nancy Grace Roman Space Telescope. STScI also houses the Barbara A. Mikulski Archive for Space Telescopes (MAST) which is a NASA-funded project to support and provide to the astronomical community a variety of astronomical data archives, and is the data repository for the Hubble, Webb, Roman, Kepler, K2, TESS missions and more. STScI is operated by the Association of Universities for Research in Astronomy in Washington, D.C.
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