It turns out that stars like our sun may not have to be alive and thriving to sustain life. Scientists say they have discovered a possible "major planet" orbiting a dying sun that could potentially support life for generations to come.
Researchers from University College London made the "unexpected" discovery while observing a white dwarf, the glowing remains of a star that ran out of its hydrogen fuel, 117 light years away. This particular star, known as WD1054-226, has a ring of planetary debris in its orbital habitable zone, otherwise known as the Goldilocks zone, where the temperatures should, in theory, allow the planet to have liquid water on its surface.
If the object discovered is confirmed to be a life-supporting planet, it would mark the first time a life-supporting planet has been found orbiting a dying sun.
Scientists made the discovery while measuring light from the white dwarf and published their findings in the Monthly Notices of the Royal Astronomical Society. They said they found pronounced dips in light that corresponded to 65 evenly spaced clouds of debris that orbited WD1054-226 every 25 hours.
"The moon-sized structures we have observed are irregular and dusty (e.g. comet-like) rather than solid, spherical bodies," UCL Physics and Astronomy professor Jay Farihi, the lead author of the study, said in a statement. He said the structures are currently a "mystery we cannot explain," but offered one likely, and "unexpected" possibility: a nearby planet.
"An exciting possibility is that these bodies are kept in such an evenly-spaced orbital pattern because of the gravitational influence of a nearby planet. Without this influence, friction and collisions would cause the structures to disperse, losing the precise regularity that is observed. A precedent for this 'shepherding' is the way the gravitational pull of moons around Neptune and Saturn help to create stable ring structures orbiting these planets," Farihi said, adding that he and his team "were not looking for this."
The possibility of a "major planet" in the star's habitable zone is exciting, but he stressed such a planet is not yet confirmed. Farihi said his team still needs more evidence, which may be difficult because they can't directly observe the planet. Instead, they may have to rely on computer models with other observations of the star and its orbiting debris to get a clearer answer.
The team expects that if there is in fact a planet, it was only recently developed — and that it would be habitable for at least 2 billion years, including at least 1 billion years in the future.
Their discovery could also help scientists develop a better understanding of our own solar system, as more than 95% of all stars, including our sun, will eventually become white dwarfs.
"Since our sun will become a white dwarf in a few billion years," Farihi said, "our study provides a glimpse into the future of our own solar system."
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