The Universe is truly full of wonders, and the James Webb Space Telescope has just given us our best views of one of them.
The object in question is a star about 5,600 light-years away, and Webb’s infrared eye has discovered an extraordinary detail: It’s surrounded by what appear to be concentric rings of light radiating outward.
While Webb .’s hallmark diffraction peaks are not ‘real’, which are concentric rings – and there is a wonderful and fascinating explanation for this.
The star is actually a binary pair of rare stars in the constellation Swan, and their interactions produce precise periodic bursts of dust that expand in shells over time in the space around the pair.
These dust jackets glow in infrared, making an instrument as sensitive as Webb’s MIRIA to solve them down to the smallest detail.
The star is what is known as a colliding wind binary, consisting of an extremely rare Wolf-Rayet star, named WR 140, and a hot, massive O-type star companion – another rare object.
Wolf-Rayet stars are very hot, very luminous and very old; at the end of their main sequence life. They are significantly depleted in hydrogen, rich in nitrogen or carbon, and are losing mass at a very rapid rate.
O-type stars are among the most massive stars known, also very hot and bright; because they are so huge, their lifespans are incredibly short.
Both stars in the WR 140 system have fast stellar winds, blowing into space at a speed of about 3,000 kilometers (1,864 miles) per second. Both are therefore losing mass at a pretty furious pace. So much for normal, for both stars.
Where it gets interesting is their orbit, which is elliptical. This means that the stars do not describe nice, tight circles around each other, but ovals, with a point at which they are furthest apart (apastron) and a point at which they are closest to each other (periastron).
When the two stars enter the periatron — a distance about a third greater than the distance between Earth and the sun — they get close enough that their powerful winds collide.
This causes shocks in the material around the stars, accelerates particles and generates energetic radiation, such as X-rays. These colliding winds also cause periods of dusting as the material in the colliding stellar wind cools.
This process can be seen in the animation below, which shows what the system would look like from top to bottom.
The dust is a form of carbon, which absorbs ultraviolet light from the two stars. This heats the dust, causing it to re-emit thermal radiation — which Webb observes in infrared wavelengths.
The dust is then blown out by the stellar wind, resulting in the expansion of the partial dust shells. They expand and cool when blown out, losing heat and density.
What you look at in Webb’s image is a bit like a series of bubbles; the edge of each dust envelope is more visible because you look at a denser concentration of material through the perspective.
Because the binary’s orbit has a period of 7.94 years, the wind collision and dust production occur like clockwork every 7.94 years. This means you can count the rings of the nebula around the binary star, such as tree rings, to determine the age of the outer visible dust envelope.
About 20 rings are visible, which means you can see about 160 years of dust casings in the Webb image. The most recent WR 140 periastron was observed in 2016.
Webb’s observation of WR 140 was requested by a team led by astrophysicist Ryan Lau of the Japan Aerospace Exploration Agency’s Institute of Space and Astronautical Science.
They are preparing a paper on the observationsso it’s possible we’re about to discover something new about this fascinating crazy star.
#Extraordinary #phenomenon #space #captured #mesmerizing #image