Astronomers Discover White Dwarf Snacking on Icy Planet Fragment

A team of astronomers using the Hubble Space Telescope has made an intriguing discovery involving a white dwarf, the remnant of a dying star, which has been consuming material from a fragment identified as originating from a Pluto-like object. This finding, detailed in a paper published on September 18, 2023, in the Monthly Notices of the Royal Astronomical Society, highlights a remarkable cosmic event that offers insights into both the past and future of celestial bodies.

Researchers observed the white dwarf, designated WD 1647+375, and noted its unusual composition, which deviates from the typical atmosphere of white dwarfs that mainly consist of hydrogen and helium. Notably, WD 1647+375 exhibited an unexpected abundance of volatile elements like carbon, sulfur, nitrogen, and oxygen. This unusual chemical makeup suggests that the fragment it consumed may have once housed water, indicating it was an icy planetesimal.

Unraveling the Cosmic Mystery

According to lead author Snehalata Sahu, the phenomenon can be likened to a “cosmic crime scene.” The intense gravitational pull of the white dwarf likely captured the icy planet from its original orbit, providing a rare glimpse into the processes that occur when celestial bodies collide or merge. The elemental composition of the accreted material leaves behind chemical fingerprints that allow scientists to infer the characteristics of the consumed object.

The team noted that the nitrogen present in WD 1647+375 serves as a significant indicator of the icy nature of the victim. Furthermore, the dwarf’s elevated oxygen levels pointed to the fact that the object it consumed was not rocky but rather icy, similar to the surface of Pluto, which is known for its nitrogen ices. Sahu remarked, “We think that the white dwarf accreted fragments of the crust and mantle of a dwarf planet.”

Analysis of Hubble’s ultraviolet data indicates that the white dwarf has been feasting on this object for at least the last 13 years, consuming material at a staggering rate of approximately 440,925 pounds (200,000 kilograms) per second. This suggests that the original icy body had a minimum diameter of about 3 miles (5 kilometers).

Implications for Cosmic Evolution

The implications of this discovery extend beyond just the observation of a white dwarf’s diet. The research provides valuable insights into the dynamic nature of cosmic systems and the potential for icy planetesimals to deliver essential resources, such as water, to terrestrial planets in different solar systems. According to the study, these processes are crucial for the development of life elsewhere in the universe.

This finding also opens up avenues for further exploration of similar icy objects, including the recently observed interstellar comet 3I/ATLAS. Understanding these celestial bodies can help researchers piece together the history and evolution of planetary systems.

Looking ahead, the study offers a glimpse into the fate of our own solar system. As our Sun eventually exhausts its nuclear fuel and transitions into a white dwarf like WD 1647+375, the planets of our solar system may face a similar destiny to the icy planetesimal consumed by this star. Sahu concluded, “If an alien observer looks into our solar system in the far future, they might see the same kind of remains we see today around this white dwarf.”

This remarkable discovery not only enriches our understanding of stellar evolution but also emphasizes the interconnectedness of cosmic events across the universe.