In a distant star system, scientists studying a white dwarf named “WD 1647+375” have found strong evidence that this star is swallowing debris from a planet or icy asteroid rich in volatiles such as water and nitrogen.

White dwarfs represent the final stage in the life of most stars, including our sun in the future. When a star exhausts its nuclear fuel and hydrogen and helium fusion in its core stops, it loses balance and expands into a massive red giant, then ejects its outer layers as a colorful planetary nebula, leaving only the star’s core, known as a “white dwarf.”

Usually, white dwarf envelopes consist of hydrogen or helium after nuclear fuel is depleted, so the presence of elements like carbon, oxygen, sulfur, and a large amount of nitrogen in the star’s atmosphere is evidence that the star is accumulating material from a nearby disrupted body.

Using the Hubble Observatory

By using ultraviolet light via the Hubble Space Telescope, researchers analyzed the chemical spectrum of the star’s atmosphere. They found that the nitrogen content in the material absorbed from the swallowed planet approximates 5% of the mass, the highest nitrogen level ever observed in debris absorbed from a celestial body around a white dwarf star.

The oxygen amount also exceeds what would be expected if the debris were only rocky, confirming its icy nature and volatile content, according to the study published in the “Monthly Notices” journal of the Royal Astronomical Society in the UK.

Calculations estimate that the icy body supplied the star with material at a rate of about 200,000 kilograms per second over the last 13 years of observation.

Significance of the Discovery

This scientific discovery is significant for several reasons. First, it provides clear evidence of the existence of icy bodies and water resources in planetary systems outside our solar system, supporting the idea that water and compounds essential for life may be common in the universe, not limited to our system alone.

Second, detecting nitrogen-rich bodies helps us understand the volatile components that make up small planets or comets in distant celestial bodies, contributing to mapping the diversity of small planets among different stars.

Finally, white dwarf stars act as a “cosmic crime scene,” when they swallow nearby objects, leaving their chemical residues in their atmosphere, allowing scientists to “reconstruct” the nature of those bodies containing water or volatile gases.

Remaining Questions

However, important questions remain: Was this icy body part of a previous planetary system of the star? Or did it come from outside the system, like an interstellar comet captured by the star’s gravity? What was the process of its destruction and absorption that led to the spread of these materials in the star’s atmosphere?

Researchers from the University of Warwick, which led the study, added in an official press release that continued monitoring and spectroscopic imaging are necessary to discover more similar cases, whether around other white dwarf stars or stars in other evolutionary stages.