Thanks to two decades of optical data collected from Keck's Hawaii Observatory and the addition of new infrared data from James Webb's machine, astronomers have for the first time seen directly how intense star light can push matter.
Researchers from Cambridge and Sydney universities observed on Mount Keck a giant plume of dust created by the violent interaction of two massive stars in the binary system WR 140, but recently Webb was able to look much deeper and photograph not one accelerating dust plume, but about 20 inside each other, forming a system of concentric rings.
Light irradiation pressure
At a distance of just over 5,000 light years from the Earth, the binary system WR140 consists of a huge Wolf-Rayet star and an even larger blue supergiant star, gravitationally bound by an eight-year orbit. WR140 emits plumes of dust extending thousands of times the distance between Earth and the Sun, which, every eight years, gives astronomers a unique opportunity to observe how star light can affect matter.
In fact, light transmits the impulse to the matter known as radiation pressure, a phenomenon that is often seen as a jet of matter moving through space at a high speed, but it is not easy to capture the actual drive by recording acceleration by radiation rather than gravity.
Starstorms and Interferometrics
WR140 is a particularly suitable system for verifying this phenomenon. In fact, it is a binary star whose intense field of radiation makes it available for high-quality data. In addition, the Star Winds of the Wolf-Rayet stars are very strong, like a real star hurricane. Elements like carbon condense in the wind in the form of dust that remains hot enough to glow in the infrared range. Like smoke in the wind, it gives telescopes something that you can see.
The team using the Keck telescope used image formation technology known as interferometry, which was able to act as a kind of zoom for a 10-metre mirror. This allowed researchers to obtain sufficiently clear images of WR140 for research.
At the same time, Khan and his team discovered that the dust in the plume did not leave the star with the star wind; instead, it formed at a point where the winds of the two stars were colliding; because the orbital binar star was in constant motion, the dust plume was wrapped in a spiral.
Dust rings are thrown back every eight years.
But the surprises weren't over. The picture taken by James Webb actually showed at least 17 concentric dust rings coming from a pair of stars. Each ring was formed when two stars drew closer together and their star winds met, compressing gas and forming dust particles. Research estimates that the ring is formed once for each completed orbit, that is, every 7.93 years.
Moreover, in this particular system, the orbit of the Wolf-Rayet star is elliptical rather than circular. As a result, the stars are close enough to produce dust only for short periods during their orbits. This creates a unique pattern of the ring. Moreover, WR 140 rings are not perfectly circular. Moreover, in some places they look brighter and in others almost invisible. This is because:
- Dust production changes as the stars approach each other. Webb sees the system not directly in the orbit of the stars, but in an angle.
Webb's image was obtained with a medium infrared tool number 1349.
Light accelerates matter.
The researchers built a model to explain the build-up of dust. In the absence of external forces, each of them would have to expand at a constant rate. Observations said otherwise: the rate of expansion was not constant, but rather accelerating. "We caught it for the first time."
With Webb, researchers will be able to learn much more about the WR140 star system and similar systems. The space telescope has great stability and sensitivity, which will make observations much easier than from the ground, thus opening a new window into the world of Wolf-Rayet physics.