Light’s effects on matter are demonstrated by a set of stars in our galaxy. Light from stars exerts a pressure on space dust, changing its motion for the first time ever. This radiation pressure regulates the deposition of dust close to young stars and directs the formation of gas clouds around expended stars (SN: 9/22/20). The dust pattern surrounding a star pair 5,600 light-years away in the Cygnus constellation provides a unique laboratory for observing the impact in action.
Astronomers have long known that the dust released by WR 140 and its buddy is caused by the collision and condensation of gas from these two stars. But 16 years’ worth of images demonstrate that the dust is speeding up its exit from the stars. Scientists estimate that stellar dust travels away from stars at a speed of 6.5 milion km/h and accelerates to more than 10 milion km/h in a single year. If the dust were to travel at that rate, it would reach Earth from the sun in about 15 hours.
The answer was found by calculating a speed from the positions of concentric dust shells over time. According to Han of the University of Cambridge, the calculations made by the researchers demonstrate that the pressure put on the dust by light emitted from the stars is what is accelerating it. Only when all the photos are placed close to one another does radiation pressure become visible. These layers of dust are not only being pushed by the light, but they also stretch farther than any telescope could observe before this year. Han and another team report October 12 in Nature Astronomy that images from the James Webb Space Telescope, or JWST, display more of the dusty layers surrounding WR 140 and its companion than has ever been observed before.
The elaborate patterns that encircle the stars appear at first to be a huge spider web. In reality, however, they are massive, growing, cone-shaped dust shells, according to the researchers’ investigation. As the stars make another trip around their orbits, a new one begins to develop, and they are all nestled inside of one another. Because we view the shells in the new photographs from the side, Han claims that they resemble portions of rings. Because the distance between the stars varies as they orbit one another, the patterns do not entirely encircle the stars. The consequence the researchers were anticipating was that when the stars are far away, the density of the colliding gas is too low to condense to dust.
It surprised them that the gas will not really condense effectively even when the stars stand close together. That means there’s a “Goldilocks zone” for dust production, where the separation between the stars is exactly right to produce a cascade of expanding dust shells. Astrophysicist Andy Pollock of the University of Sheffield in England, who was not involved in either study, argues that “their Goldilocks zone is a new hypothesis.” “In my specialty of X-rays, something similar occurs.” According to Pollock’s research, WR 140 and its partner generate more X-rays as they come closer to one another but fewer when they get very close, indicating that there is also a Goldilocks zone for X-ray emission from the stars. He remarks that it would be intriguing to determine whether there is any relationship between the two categories of Goldilocks zones. “All of this has to work together somehow.”