White Dwarf J1328−1450 Discovered With Two Rings of Debris

Astronomers have spotted a unique white dwarf star with two distinct rings of planetary debris swirling around its dense core, a discovery that may offer a peek into one possible outcome for our solar system in the distant future. The star, named J1328−1450, is located in the Milky Way roughly 1,600 light-years from Earth in the constellation Virgo. Observations of the stellar remnant were made using the European Southern Observatory's Chile-based Very Large Telescope.

The dead core is similar to our sun, having expelled its outer layers at the end of its lifetime after previously hosting a planetary system that was vaporized to rubble. Prior to this finding, astronomers had identified 21 white dwarfs with debris surrounding them, all of which featured a single disc rather than the double-ring configuration revealed in the new observations published in the journal Nature Astronomy.

Complex Structure Around Stellar Remnants

According to astronomer Felipe Lagos-Vilches of Universidad Técnica Federico Santa María in Chile, one of the authors of the study, the finding demonstrates unexpected complexity. “It shows that the remnants of a planetary system can have a much more complex structure than we previously thought, and provides further support to the idea that planetary rocky bodies may survive the transformation of a star into a white dwarf,” Lagos-Vilches said.

The white dwarf possesses a mass about 47 percent that of the sun, packed into a diameter roughly the same as that of Earth. Researchers believe the disc may have been shaped by two planetary or smaller rocky bodies embedded in the rings after surviving the star's violent death throes. These surviving bodies may be remnants of larger, heavily disrupted planets, with one potentially around the size of the dwarf planet Pluto and another smaller than that.

The original star likely hosted a planetary system before expanding dramatically into a red giant, engulfing some innermost planets while more distant ones survived. Surviving rocky bodies may have been gravitationally perturbed onto eccentric orbits, bringing them close enough to the white dwarf to be disrupted by its gravitational force, spreading material into a gas and dust disc containing two relatively large rocky bodies.

Explaining the concentric gaseous rings, Lagos-Vilches noted that the outer ring is strongly depleted in magnesium compared with the inner ring. “This suggests that they may originate from different parent bodies, or possibly from different layers of a rocky body that was disrupted when it went too close to the white dwarf due to its strong gravitational field,” Lagos-Vilches said.

Looking ahead to our own cosmic neighborhood, Lagos-Vilches noted that in about 5 billion years, the sun will become a red giant before shedding its outer layers. While Mercury and Venus are expected to be engulfed and the fate of Earth remains uncertain, the outer planets like Jupiter and Saturn have a better chance of surviving. Eventually, surviving remnants, moons, and asteroids could be drawn close enough to be torn apart by gravitational forces, meaning “a debris disc like the one around J1328−1450 could therefore represent one possible stage in the very distant future of our own planetary system,” Lagos-Vilches said.