JWST has spotted bizarre rings of dust around a dying star

A strange star system with concentric rings of dust blowing out into space has been imaged in unprecedented detail by the James Webb Space Telescope

Space 12 October 2022

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Concentric rings of dust spreading away from a star system called WR 140

NASA/ESA/CSA/STScI/JPL-Caltech

The James Webb Space Telescope (JWST) has observed a bizarre set of rings around an unusual star system, which may be evidence for carbon that formed planets like Earth across the cosmos.

The system, called WR 140, is located about 5600 light years from Earth and contains two stars. One is a Wolf-Rayet star – a massive star eight times our sun’s mass – at the end of its life, shedding material into space. Its companion is a supergiant star some 20 times more massive than our sun. Previous observations of the system had shown two rings of carbon-rich dust emitting from the stars, puffing out as they approach each other in their eight-year orbit.

Images taken by JWST in July, however, reveal much more detail. The telescope spied more than 17 rings of dust extending from the stars “almost like tree rings”, says Ryan Lau at the National Science Foundation’s NOIRLab in Arizona who led the observations. The rings are not perfectly circular because of the angle from which we are observing the system and the orbits of the stars, making them seem almost artificial – but they are very much real.

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“We’re essentially tracing out 130 years of this eight-year cycle of dust formation,” says Lau. “It blew us away. We didn’t expect to see that many rings.”

Star systems like this with concentric rings of dust are not too uncommon, says Lau. “There are maybe 15 that are known,” he says. However, none has been seen in as much detail as this. “There’s nothing really like WR 140 where you see those series of shells further out,” says Lau. “That’s where the power of JWST comes in.”

In total, the rings extend more than 10 trillion kilometres from the stars, or about 70,000 times the distance between Earth and the sun. “It’s the furthest distance we’ve seen Wolf-Rayet dust survive,” says Lau. That could have major implications for the formation of stars and planets like our own in the cosmos. “Wolf-Rayet stars could be an importance source of the carbon that formed our sun or Earth,” says Lau.

Journal reference: Nature Astronomy, DOI: 10.1038/s41550-022-01812-x

Journal reference: Nature, DOI: 10.1038/s41586-022-05155-5

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