Tue. Jul 5th, 2022

The Sun is the source of all energy in our solar system, but what happens when this star dies – havoc. Astronomers have observed a similar development in deep space as a dead star leads to cosmic cannibalism in its own planetary system.

The dead star is siphoning off debris from both the system’s inner and outer reaches, consuming both rocky-metallic and icy material, the ingredients of planets. The event was noticed in the archival data from the Hubble space telescope and other observatories.

Astronomers are hopeful that the findings will help describe the violent nature of evolved planetary systems and can tell about the makeup of newly forming systems. The star observed is G238-44, a white dwarf.

A white dwarf is what remains of a star like our Sun after it sheds its outer layers and stops burning fuel through nuclear fusion. The findings are also intriguing because small icy objects are credited for crashing into and “irrigating” dry, rocky planets in our solar system.

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“We have never seen both of these kinds of objects accreting onto a white dwarf at the same time. By studying these white dwarfs, we hope to gain a better understanding of planetary systems that are still intact,” said Ted Johnson, the lead researcher , and a recent University of California, Los Angeles (UCLA) graduate.

This illustrated diagram of the planetary system G238-44 traces its destruction. The tiny white dwarf star is at the center of the action. (Photo: Nasa)

Theories of planetary system evolution describe the transition between a red giant star and a white dwarf phase as a chaotic process. The star quickly loses its outer layers and its planets’ orbits dramatically change. Small objects, like asteroids and dwarf planets, can venture too close to giant planets and be sent plummeting toward the star.

The study confirms the scale of this violent chaotic phase, showing that within 100 million years after the beginning of its white dwarf phase, the star is able to simultaneously capture and consume material from its asteroid belt and Kuiper belt-like regions.


When a star like our Sun expands into a bloated red giant late in its life, it will shed mass by puffing off its outer layers. One consequence of this can be the gravitational scattering of small objects like asteroids, comets, and moons by any remaining large planets.

The researchers are looking at the ultimate scenario for the Sun’s evolution, 5 billion years from now. Earth might be completely vaporized along with the inner planets. But the orbits of many of the asteroids in the main asteroid belt will be gravitationally perturbed by Jupiter and will eventually fall onto the white dwarf that the remnant Sun will become.

“After the red giant phase, the white dwarf star that remains is compact no larger than Earth. The wayward planets end up getting very close to the star and experience powerful tidal forces that tear them apart, creating a gaseous and dusty disk that eventually falls onto the white dwarf’s surface, “Johnson explained.

The team’s results were presented at an American Astronomical Society (AAS) press conference.

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