Astronomers have identified an unusual structure surrounding the white dwarf J1328−1450, the remnant core of a star similar to the Sun. Observations conducted with the European Southern Observatory's Very Large Telescope (VLT) revealed two concentric debris discs separated by a distinct gap. This discovery, published this week in Nature Astronomy, provides new data on the destiny of planetary systems following the death of their host stars.
The configuration differs from other similar systems and appears to be maintained by two planetary bodies that survived the star's transformation. Researchers estimate that one object is comparable in size to an asteroid, while the other could reach the dimensions of Pluto or even the Moon. This system offers critical clues regarding what might happen to our own Solar System in the distant future.
Stars like the Sun undergo intense changes in their final stages, expanding and shedding outer layers that can engulf and destroy nearby planets. After this process, remaining rocky bodies may fragment to form a debris disc around the dead star. However, in the case of J1328−1450, researchers found an uncommon setup where material is distributed in two concentric rings rather than a single one. The team notes that the separation between these rings remains stable, a characteristic likely linked to the presence of two bodies in distinct orbits.
Nicola Gentile Fusillo, an astronomer at the University of Trieste in Italy and the study's lead author, stated that while there was prior evidence that planets could survive their stars' transformation, this is the first identified example of a complex system featuring a double debris disc and the possibility of two remaining planetesimals.
To investigate the structure, astronomers utilized the X-shooter instrument on the VLT in Chile's Atacama Desert. Measurements of the gas velocity orbiting the white dwarf identified two distinct movement patterns, confirming the presence of two separate discs. The observations also detected calcium, oxygen, magnesium, and iron in the material surrounding the star, indicating a composition similar to rocky planetary materials found in the Solar System.
Despite general similarities, the two rings exhibit chemical differences. The inner disc is rich in magnesium gas, whereas the outer disc has lost much of this element. Researchers suggest this could indicate that the bodies feeding the rings originated from planets with distinct compositions. Alternatively, the material may have come from different regions of a single celestial body, such as a planet's crust and core.
The study also offers a perspective on the future evolution of the Solar System. In the distant future, the Sun is expected to transform into a white dwarf, a process that could destroy Earth. Felipe Lagos-Vilches, a co-author of the research and astronomer at the University of Warwick in the UK and the Universidad Técnica Federico Santa María in Chile, highlighted that the observed system allows scientists to investigate how planetary structures can persist around stars after their transformation.
Sources: Olhar Digital.