{"id":4996,"date":"2022-11-01T22:00:00","date_gmt":"2022-11-01T22:00:00","guid":{"rendered":"https:\/\/modernsciences.org\/staging\/4414\/?p=4996"},"modified":"2022-10-21T13:45:39","modified_gmt":"2022-10-21T13:45:39","slug":"alien-megastructures-cosmic-thumbprint-whats-behind-a-james-webb-telescope-photo-that-had-even-astronomers-stumped","status":"publish","type":"post","link":"https:\/\/modernsciences.org\/staging\/4414\/alien-megastructures-cosmic-thumbprint-whats-behind-a-james-webb-telescope-photo-that-had-even-astronomers-stumped\/","title":{"rendered":"Alien megastructures? Cosmic thumbprint? What\u2019s behind a James Webb telescope photo that had even astronomers stumped"},"content":{"rendered":"\n
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\n \n NASA \/ ESA \/ CSA \/ STScI \/ JPL \/ Caltech<\/span><\/span>\n <\/figcaption>\n <\/figure>\n\nPeter Tuthill<\/a>, University of Sydney<\/a><\/em><\/span>\n\n

In July, a puzzling new image of a distant extreme star system surrounded by surreal concentric geometric rungs had even astronomers scratching their heads. The picture, which looks like a kind of \u201ccosmic thumbprint\u201d, came from the James Webb Space Telescope, NASA\u2019s newest flagship observatory. <\/p>\n\n

The internet immediately lit up with theories and speculation. Some on the wild fringe even claimed it as evidence for \u201calien megastructures\u201d of unknown origin. <\/p>\n\n

Luckily, our team at the University of Sydney had already been studying this very star, known as WR140, for more than 20 years \u2013 so we were in prime position to use physics to interpret what we were seeing.<\/p>\n\n

Our model, published in Nature<\/a>, explains the strange process by which the star produces the dazzling pattern of rings seen in the Webb image (itself now published in Nature Astronomy<\/a>). <\/p>\n\n

The secrets of WR140<\/h2>\n\n

WR140 is what\u2019s called a Wolf-Rayet star<\/a>. These are among the most extreme stars known. In a rare but beautiful display, they can sometimes emit a plume of dust into space stretching hundreds of times the size of our entire Solar System. <\/p>\n\n

The radiation field around Wolf-Rayets is so intense, dust and wind are swept outwards at thousands of kilometres per second, or about 1% the speed of light. While all stars have stellar winds, these overachievers drive something more like a stellar hurricane.<\/p>\n\n\n\n

Critically, this wind contains elements such as carbon that stream out to form dust. <\/p>\n\n

WR140 is one of a few dusty Wolf-Rayet stars found in a binary system. It is in orbit with another star, which is itself a massive blue supergiant with a ferocious wind of its own. <\/p>\n\n

\n \"\"<\/a>\n
\n The binary stars of the WR140 system.<\/span>\n Amanda Smith \/ IoA \/ University of Cambridge<\/span>, Author provided<\/span><\/span>\n <\/figcaption>\n <\/figure>\n\n

Only a handful of systems like WR140 are known in our whole galaxy, yet these select few deliver the most unexpected and beautiful gift to astronomers. Dust doesn\u2019t simply stream out from the star to form a hazy ball as might be expected; instead it forms only in a cone-shaped area where the winds from the two stars collide.<\/p>\n\n

Because the binary star is in constant orbital motion, this shock front must also rotate. The sooty plume then naturally gets wrapped into a spiral, in the same way as the jet from a rotating garden sprinkler. <\/p>\n\n

WR140, however, has a few more tricks up its sleeve layering more rich complexity into its showy display. The two stars are not on circular but elliptical orbits, and furthermore dust production turns on and off episodically as the binary nears and departs the point of closest approach. <\/p>\n\n

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