Astronomers Mark First-Ever Observation of White Dwarf Consuming a Dead Planet

© Photo : Mark A. GarlickArtist's impression of two white dwarfs merging
Artist's impression of two white dwarfs merging - Sputnik International, 1920, 10.02.2022
Astronomers for the first time have watched a dead sun, a white dwarf, gobble up a dead planet, according to a new study published in Nature. The event has long been hypothesized but never observed.
The authors of the study used NASA's Chandra X-ray Observatory, focusing on a white dwarf called G29–38 located some 45 light-years from Earth. The team observed a blast of X-ray emissions from the white dwarf. The estimated 1.8 million degrees Fahrenheit heat aligned with models of planetary bodies crashing into white dwarves, according to the researchers.

"This detection provides the first direct evidence that white dwarfs are currently accreting the remnants of old planetary systems," Tim Cunningham, lead author of the study, said.

He added that the event could be a glimpse into the future of other solar systems. "Probing accretion in this way [offers] a glimpse into the likely fate of the thousands of known exoplanetary systems, including our own solar system," he suggested.

An estimated 97% of stars in our Milky Way galaxy end their lives as white dwarfs. When a so-called Main Sequence star runs out of fuel, it expands into a red giant, vaporizing any nearby orbiting planets, before erupting in an explosion of superheated gas.
Following the rapid expansion and eruption, it collapses in on itself and forms a white dwarf, effectively packing the mass of a sun into a celestial body no larger than our Earth. For reference, 1.3 million Earths could fit inside the Sun, which has 333,000 times the mass of Earth.
Astronomers suggest that the remnants of a solar system can orbit around a white dwarf in a debris disk, sometimes crashing into the white dwarf and becoming a part of it. Previous studies have found traces of heavy metals, such as iron and magnesium mixed in the atmosphere of a white dwarf, lending credence to the theory.
Astronomers previously relied on a technique known as spectroscopy. By studying the wavelengths emitted by the object they could determine its physical composition. The only evidence, until the X-ray study, that white dwarfs slowly consume the remnants of their solar system was indirect.
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