In our closest stellar neighborhood, a burned-out star is devouring a fragment of an object similar to Pluto. Thanks to its unique ultraviolet capabilities, only NASA’s Hubble Space Telescope was able to detect this meal taking place.
Detected cosmic absorption
A stellar remnant is a white dwarf, which has about half the mass of our Sun but is tightly packed into a body about the size of Earth. Scientists believe that the dwarf’s enormous gravity attracted and tore apart Pluto’s icy counterpart from its own version of the Kuiper Belt, an icy ring of debris surrounding our Solar System.
Researchers were able to determine this destruction by analyzing the chemical composition of the doomed object as its debris fell onto the white dwarf. In particular, they discovered “volatile substances” — substances with low boiling points, including carbon, sulfur, nitrogen, and high oxygen content, indicating a significant presence of water.
The scientists were surprised because they did not expect to find such icy substances. It is believed that they are ejected from their planetary systems too early, when stars evolve into white dwarfs. However, it was precisely this type of material, rich in volatile substances, that was discovered.
What did the Hubble spectrograph show?
Using the Hubble spectrograph to study cosmic origins, the team discovered that the fragments consisted of 64% water ice. The fact that they found so much ice meant that these fragments were part of a very massive object that formed far away in the icy analogue of a star system’s Kuiper belt. Using data from Hubble, scientists calculated that the object was larger than typical comets and could be a fragment of exo-Pluto.
They also discovered a large proportion of nitrogen — the largest ever found in white dwarf debris systems. The accumulation of these objects, rich in volatile substances, white dwarfs, is very difficult to detect in visible light. These volatile elements can only be detected using the Hubble telescope’s unique sensitivity to ultraviolet light. In optical light, the white dwarf would appear normal.
Located approximately 260 light-years away, the white dwarf is a relatively close cosmic neighbor. In the past, when it was a star similar to the Sun, one would expect it to have planets and an analogue of our Kuiper belt.
How to see our Sun in the future
Billions of years from now, when our Sun burns out and becomes a white dwarf, objects in the Kuiper Belt will be drawn in by the immense gravity of the star’s remains. “These planetesimals will be destroyed and accreted,” said Snehalata Sahu of the University of Warwick in the UK, lead author of the study. If an alien observer looks at our Solar System in the distant future, they may see the same remnants that we see today around this white dwarf.
The team hopes to use NASA’s James Webb Space Telescope to detect molecular features of volatile substances such as water vapor and carbonates by observing this white dwarf in infrared light. By studying white dwarfs further, scientists will be able to better understand the frequency and composition of these volatile-rich accretion processes.
Sahu is also monitoring the recent discovery of interstellar comet 3I/ATLAS. She is really interested in learning about its chemical composition, especially its water content. “Such studies will help us learn more about how planets form. They will also help us understand how water gets onto rocky planets,” said Sahu.
According to phys.org
