Article by: Andacs Robert Eugen, on 25 June 2022, at 11:23 am Los Angeles time

The Hubble Space Telescope observed a white dwarf star devouring rock and ice from its own planetary system. This suggests that water and other volatiles may be common in the outer areas of planetary systems.

Astronomers used archival data from the Hubble Space Telescope and other observatories to analyze the spectral properties of the white dwarf star G238-44. Detected elements show that the dead star swallows debris from both the inside and the outside of its system. It is a case of "cosmic cannibalism," say the study's authors, published on the Hubble Telescope website.

"I've never seen both types of objects come together on a white dwarf at the same time," said Ted Johnson, lead researcher and graduate of the University of California, Los Angeles, in a statement.

"By studying these white dwarf stars, we hope to better understand the planetary systems that are still intact," he explained.

G238-44 was a Sun-like star that lost its outer layers and no longer burned fuel through nuclear fusion. The discovery that stellar debris simultaneously captures matter from its asteroid belt and Kuiper belt-like regions at the edge of the solar system, including ice bodies, is significant because it suggests that a "water tank" may be a common feature in outer areas. of planetary systems.

"Life, as we know it, needs a rocky planet covered with a variety of elements, such as carbon, nitrogen, and oxygen," said Benjamin Zuckerman, a professor emeritus at UCLA's Astronomy and Astrophysics Division and co-author of research.

"The abundance of elements we see on this white dwarf star seem to require both a rocky body and one rich in volatile substances. It is the first example I found studying hundreds of white dwarf stars, "he explained.

When a star like the Sun expands and becomes a red giant, at the end of its life, it loses mass by releasing its outer layers. A consequence of this may be the gravitational scattering of small objects, such as asteroids, comets and satellites, to the large planets in the system. Hit in this way, surviving objects can be thrown into very eccentric orbits.

"After the phase of the red giant, the remaining white dwarf star is compact - no bigger than Earth. The planets get very close to the star and experience strong forces of attraction that break them to pieces, creating a disk of gas and dust that eventually falls on the surface of the white dwarf star, "said Johnson.