Ice Bodies in Exoplanetary Systems: A New Discovery

In our solar system, comets and icy planetary bodies are believed to have been responsible for delivering water to Earth. The presence of these icy bodies is considered essential for the development of life on other worlds. However, identifying them outside our solar system is extremely challenging due to their small size and faint brightness, necessitating precise chemical analysis.

Recent Evidence of Icy Bodies

In a study published in the journal MRNAS, astronomers from the University of Warwick in Europe and the United States found strong evidence of volatile-rich bodies, which could provide water and life components, in planetary systems beyond our solar system.

The team used ultraviolet spectroscopy from the Hubble Space Telescope to study the chemical composition of distant stars. A particular star, named WD 1647+375, stood out for having volatiles on its surface.

Discovery of Unique Chemical Materials

White dwarf atmospheres typically consist of hydrogen and helium, but this star showed elements like carbon, nitrogen, sulfur, and oxygen, indicating the ingestion of an icy body by the star.

The study’s lead author, Snehilata Sahu, explained that white dwarfs often show signs of calcium, iron, and other metals from absorbed materials. However, the presence of volatile-rich substances is exceedingly rare.

The Significance of Nitrogen as a Chemical Indicator

Nitrogen is a crucial chemical element in identifying icy worlds. Spectroscopic analysis revealed that the materials absorbed by the star contained a high nitrogen content, the highest detected so far in white dwarf debris.

Additionally, data showed that the debris had been feeding the star for at least 13 years at a rate of 200,000 kg per second, suggesting that the icy body was at least the size of a comet.

Comparison with Kuiper Belt Objects

The volatile-rich composition of star WD 1647+375 resembles Kuiper Belt objects in our solar system, which are located beyond Neptune’s orbit. It is believed that the absorbed objects might be part of a dwarf planet like Pluto.

This belief is based on the nitrogen-rich composition, high expected mass, and the ice-to-rock ratio, suggesting they could be from the crust or mantle of a Pluto-like planet.

Conclusion

This discovery is the first of its kind to prove the absorption of an icy planetary body by a hydrogen-atmosphere white dwarf. Whether this body formed in the planetary system around the original star or is an interstellar comet captured from deep space, the finding provides compelling evidence of volatile-rich bodies in planetary systems beyond our solar system.

The discovery also highlights the unique role of ultraviolet spectroscopy in exploring the compositions of rare volatile-rich bodies outside our solar system, which will be a significant part of future attempts to search for life components around other stars.