Tuesday , May 17 2022

Astronomers found a planet that survived the death of its star



On Wednesday in the journal Nature, astronomers reported observing a captivating preview of the later life of our solar system: a planet the size of Jupiter orbiting a white dwarf about 6,500 light-years away. Known as MOA-2010-BLG-477Lb, the planet occupies an orbit comparable to Jupiter. The discovery not only offers a vision of our cosmic future, but raises the possibility that any life in “surviving” worlds can withstand the death of its stars.

“While there is ample evidence of rocky planetary remains orbiting white dwarfs, we have very few data points on intact planets,” said Joshua Blackman, a postdoctoral researcher at the University of Tasmania and lead author of the study.

“The fate of our solar system is likely to be similar to MOA-2010-BLG-477Lb,” he added in an email. “The sun will become a white dwarf, the inner planets will be swallowed up and the wider orbiting planets like Jupiter and Saturn will survive.” The planet was first seen due to the light-distorting effects of its gravitational field, a phenomenon known as microlensing. After searching for years for its host star with the Keck II telescope in Hawaii, Dr. Blackman and colleagues concluded that it was orbiting a white dwarf too weak to observe it directly.

Astronomers who used a different method last year reported detecting another intact Jupiter-like planet, known as WD 1856 b, orbiting a white dwarf closely. But MOA-2010-BLG-477Lb surrounds its hidden stellar shell at almost three times the distance between Earth and the sun, making it the first known planet to occupy a Jupiter-like orbit around a white dwarf. WD 1856 b, by contrast, orbits its white dwarf every 1.4 days, suggesting that it migrated to its current position after the death of its star, although the exact mechanics of this journey still is being deleted.

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

“If I had to guess, I’d say his is a much more common population because he just has to stay there and nothing happens to him,” Dr. Vanderburg said. “That seems to me the most likely outcome, at least at this point in the history of the universe.” New discoveries may provide insights into the search for extraterrestrial life and the possible habitability of white dwarf systems. Lisa Kaltenegger, director of the Carl Sagan Institute at Cornell University, has suggested that some life-bearing stellar systems might even experience what she calls a “second genesis” in which new organisms emerge in the reconfigured fall of a white dwarf system.

“I find the study exciting because it adds to the growing evidence that planets can survive the death of their star, leading to intriguing questions about the future of the cosmos,” said Dr. Kaltenegger, who be part of the team that discovered WD 1856 b, in an email. “If the planets can survive the death of their stars, can life too?” “This is the first detection of a planet orbiting a white dwarf made using the microlensing technique,” Dr. Blackman concluded, “but it will almost certainly not be the last.”

Becky Ferreira is a NYT journalist © 2021

The New York Times

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