'Cosmic Cannibalism': Astronomers Capture Dying Star’s Last Act As It Destroys All Its Planets - Science And Nature

Jul 5, 2022

'Cosmic Cannibalism': Astronomers Capture Dying Star’s Last Act As It Destroys All Its Planets

When white dwarfs go berserk, their planets endure the ensuing mayhem. After consuming planetary and cometary debris, the evidence appears in and around the dying star's atmosphere much later. 

This is the conclusion reached by a team of UCLA astronomers after conducting a comprehensive analysis of the neighbouring white dwarf G238-44. They discovered a case of cosmic cannibalism at this fading star 86 light-years away from Earth.

If this star were in the position of the Sun, it would consume the Kuiper Belt's planets, asteroids, and comets. Meaning all the planets from Mercury to Neptune would have been consumed by this star.  This cannibalism crime is one of the most common in history due to the extensive smorgasbord.

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

Johnson was a member of a team from UCLA, UC San Diego, and the University of Kiel in Germany that studied chemical components identified in the atmosphere of white dwarfs. NASA's defunct Far Ultraviolet Spectroscopic Explorer, the Keck Observatory's High-Resolution Echelle Spectrometer in Hawaii, and the Hubble Space Telescope's Cosmic Origins Spectrograph and Space Telescope Imaging Spectrograph were utilized to collect data. The researchers discovered and measured the existence of several elements, including nitrogen, oxygen, magnesium, silicon, and iron.

Iron is especially intriguing since it forms the cores of rocky planets such as Earth and Mars. Its existence indicates that planets of a terrestrial composition originally orbited G238-44. High levels of nitrogen indicate that the system also had a pool of ice corpses.

As stars like the Sun reach extreme old age, they leave behind white dwarfs, which are their charred cores. Over billions of years, these stellar remnants gradually cool down. However, before this moment, the real dying throes may be rather violent and nasty. They then consume the planets around them. The finding of "remnants" of these planets, comets, and asteroids in the atmosphere of G238-44 is alarming for the future of our solar system.

Reference(s): NASA

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