![]() All we have to do is wait and the expanding wind inflates the dust shell like a balloon until it is big enough for our telescopes to image. Like a clockwork toy, WR140 puffs out precisely sculpted smoke rings with every eight-year orbit.Įach ring is engraved with all this wonderful physics written in the detail of its form. The final outcome of all this physics is arrestingly beautiful. When it catches the intense radiation streaming from the star, like a yacht catching a gust, the dusty sail makes a sudden leap forward. In each orbit, it is as if the star unfurls a giant sail made of dust. Our data did not fit because the expansion speed wasn't constant: the dust was getting a boost from radiation pressure.Ĭatching that for the first time on camera was something new. This acceleration turned out to be the one missing element in the models for WR140. Credit: Yinuo Han / University of Cambridge, Author provided In each eight-year orbit, a new ring of dust forms around WR140. The force fades quickly with distance, so to see material being accelerated you need to track very accurately the movement of matter in a strong radiation field. The outcome of this phenomenon, in the form of matter coasting at high speed around the cosmos, is evident everywhere.īut it has been a remarkably difficult process to catch in the act. We know that light carries momentum, which means it can exert a push on matter known as radiation pressure. Chasing that minor misfit turned out to lead us right to a phenomenon never before caught on camera. Close in right near the star, the dust was not where it was supposed to be. 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.īy modeling all these effects into the three-dimensional geometry of the dust plume, our team tracked the location of dust features in three-dimensional space.īy carefully tagging images of the expanding flow taken at the Keck Observatory in Hawaii, one of the world's largest optical telescopes, we found our model of the expanding flow fit the data almost perfectly.Įxcept for one niggle. WR140, however, has a few more tricks up its sleeve layering more rich complexity into its showy display. The sooty plume then naturally gets wrapped into a spiral, in the same way as the jet from a rotating garden sprinkler. ![]() Dust doesn't 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.īecause the binary star is in constant orbital motion, this shock front must also rotate. 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. It is in orbit with another star, which is itself a massive blue supergiant with a ferocious wind of its own. WR140 is one of a few dusty Wolf-Rayet stars found in a binary system. Credit: Amanda Smith / IoA / University of Cambridge, Author providedĬritically, this wind contains elements such as carbon that stream out to form dust. While all stars have stellar winds, these overachievers drive something more like a stellar hurricane. The radiation field around Wolf-Rayets is so intense, dust and wind are swept outwards at thousands of kilometers per second, or about 1% the speed of light. ![]() 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. These are among the most extreme stars known. WR140 is what's called a Wolf-Rayet star. Our model, published in Nature, 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). ![]() Luckily, our team at the University of Sydney had already been studying this very star, known as WR140, for more than 20 years-so we were in prime position to use physics to interpret what we were seeing. Some on the wild fringe even claimed it as evidence for "alien megastructures" of unknown origin. The internet immediately lit up with theories and speculation.
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