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Astronomers found planet that survived the death of its star

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When our sun enters its agony in about five billion years, it will incinerate our planet and then dramatically collapse into a dead embers known as the white dwarf. But the fate of more distant planets, such as Jupiter or Saturn, is less clear.

In the journal Nature on Wednesday, astronomers reported observing a tantalizing glimpse of our solar system’s beyond: a Jupiter-sized planet orbiting a white dwarf some 6,500 light-years away. here.

Known as MOA-2010-BLG-477Lb, the planet occupies an orbit comparable to that of Jupiter. The discovery not only offers a glimpse into our cosmic future, but raises the possibility that all life on “surviving” worlds could endure the death of their stars.

“While there is a lot of evidence for rocky planetary debris orbiting white dwarfs, we have very little data points from intact planets,” said Joshua Blackman, postdoctoral researcher at the University of Tasmania and senior author of study.

“The fate of our solar system will likely be similar to that of MOA-2010-BLG-477Lb,” he added in an email. “The sun will become a white dwarf, the inner planets will be engulfed, and larger orbiting planets like Jupiter and Saturn will survive. “

The planet was first spotted due to the light distorting effects of its gravitational field, a phenomenon known as a microlens. After years of searching for its host star with the Keck II telescope in Hawaii, Dr Blackman and his colleagues concluded that it was orbiting a white dwarf too weak to be observed directly.

Last year, astronomers using a different method reported spotting another unspoiled Jupiter-like planet known as WD 1856b in narrow orbit around a white dwarf. But MOA-2010-BLG-477Lb circles its hidden stellar envelope nearly three times the distance between Earth and the sun, making it the first known planet to occupy a Jupiter-like orbit around a dwarf. White. WD 1856b, on the other hand, orbits its white dwarf every 1.4 days, suggesting that it has migrated to its current position after the death of its star, although the exact mechanics of this trip are still underway. being analyzed.

Andrew Vanderburg, an assistant professor of physics at the Massachusetts Institute of Technology who led the team that discovered WD 1856b, said the new study’s findings look solid. He also noted that planets with wide orbits around white dwarfs are likely more abundant than those with tight orbits, but the latter group is easier to detect.

“If I had to guess, I would say theirs is a much more common population because they just have to stay there and nothing happens to them,” Dr Vandenburg said. “That seems to me to be the most likely outcome, at least at this point in the history of the universe.”

The new findings may provide insight into the search for extraterrestrial life and the potential habitability of white dwarf systems. Lisa Kaltenegger, director of the Carl Sagan Institute at Cornell University, has suggested that some life-bearing star systems may even experience what she calls a “second genesis” in which new organisms emerge in the reconfigured fallout from a system of white dwarfs.

“I find the study fascinating because it adds to the growing evidence that planets can survive the death of their star, which leads to intriguing questions about the future of the cosmos,” said Dr Kaltenegger, who was part of the team that discovered WD 1856b, in an email. “If the planets can survive the death of their stars, can life too?” “

Dying stars spit out harmful radiation as they grow into a phase called a red giant and introduce turbulence into their systems that could wipe out life. But there are some speculative scenarios that could preserve the habitability of white dwarf systems.

“There are a lot of things that need to be right,” said Dr. Vanderburg. He imagines a distant planet from a red giant star which then moves inward after the star has become a white dwarf and holds “enough water to potentially be a nice place to live” when the star turns. turns into a white dwarf.

Because white dwarfs are small and weak, such a planet would have to be in a very close orbit for liquid water to exist. However, if life were to emerge on a world like Jupiter’s moon Europa, which could contain an underground ocean warmed by Jupiter’s tidal forces, it could potentially survive at a greater distance from the star.

“If humanity is still here five billion years from now, we would probably have a better chance of surviving the red giant phase of the sun on a moon in Jupiter than on Earth,” Dr. Blackman said.

While the existence of life around white dwarfs remains a matter of speculation, next-generation observatories, such as the James Webb Space Telescope and the Nancy Grace Roman Space Telescope, could help provide concrete answers to some of these. evocative questions. As more and more intact planets are spotted orbiting white dwarfs, scientists will have a clearer picture of the life and afterlife of these mysterious systems.

“This is the first detection of a planet orbiting a white dwarf made using the microlens technique,” concluded Dr Blackman, “but certainly not the last.”

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