Two rare stars in the Cygnus constellation interact with each other to produce periodic dust eruptions that spread out in shells around the pair as the experience a repetitive cycle.
The James Webb Space Telescope, the most sophisticated Telescope ever launched by humankind, continues delivering mindboggling data. As it explores the universe, the space telescope is revealing some of the most distant galaxies and stars while also probing the atmosphere of distant alien worlds, revealing unprecedented details about them.
The James Webb Telescope has redefined how we explore the cosmos, and with each new observation, it makes history repeatedly over and over again. As JWST zooms into a star roughly 5,600 light years away, Webb’s infrared eye detects what appears to be concentric rings of light radiating outward from it.
In spite of Webb’s characteristic diffraction spikes not being ‘real,’ the concentric rings they form are real–and their explanation is fascinating. Two rare stars in the Cygnus constellation interact with each other to produce periodic dust eruptions that spread out in shells around the pair as the experience a repetitive cycle.
Webb’s MIRI has been able to resolve these dust shells in exquisite detail because they glow in infrared. There are two stars in this star, which is called a colliding wind binary; WR 140 is an extremely rare Wolf-Rayet star, while O-018 is a hot, massive O-type star.
A Wolf-Rayet star is extremely hot, extremely luminous, and extremely old. It is at the end of its main-sequence lifespan. Their hydrogen content is significantly low, their nitrogen and carbon content is high, and they lose mass rapidly. In addition to being extremely massive, O-type stars are also extremely hot and bright; their lifespans are extremely short due to their massive nature.
Both stars in the WR 140 system have fast stellar winds that blow out into space at approximately 3,000 kilometers (1,864 miles) per second. The mass of both is therefore eroding very rapidly.
Credits: VIDEO: NASA, ESA, Joseph Olmsted (STScI)
In the above animation, the Wolf-Rayet star approaches the O-type star, and their stellar winds collide, causing dust to be produced in the binary star system WR 140. As the mixed stellar material cools behind the O star, the stronger winds of the Wolf-Rayet star blow back and create dust. Dust will become pinwheel-shaped over time as the process repeats itself.
According to astronomers, it is their orbit that reveals something special about them. They orbit each other on elliptical paths, which means they don’t describe neat circles around each other but ovals with four points (apastron) and four points (periastron) where they are most distant from each other.
Upon reaching periastron – a distance about a third greater than the distance between Earth and the Sun – the two stars become close enough so their might stellar winds collide. The shocks caused by this force accelerate particles around the stars, creating X-rays and other energetic radiation. Colliding stellar winds also produce dust as they cool as material in them collides.
Due to the presence of carbon in the dust, the stars’ ultraviolet light can be absorbed. As a result, dust is heated, re-emitting thermal radiation at infrared wavelengths, which is what Webb observes. A stellar wind blows the dust outward, expanding the partial dust shells. In the process of being blown outward, they lose heat and density by expanding and cooling.
This stunning photograph by Webb shows the edges of dust shells more clearly since the perspective creates a denser concentration of material. Here is where it gets even more interesting.
The orbit of the binary star has a period of 7.94 years, so wind collisions and dust production occur regularly every 7.94 years. As a result, we could determine the age of the outermost visible dust shell by counting the rings of the nebula around the binary.
On the Webb image, you can see around 20 rings, indicating 160 years’ worth of dust shells. The most recent periastron observed by WR 140 was in 2016. An astrophysicist from the Institute of Space and Astronautical Science at the Japan Aerospace Exploration Agency requested Webb’s observation of WR 140. Wolf-Rayet variable star WR 140 is designated V1687 Cyg in the General Catalog of Variable Stars. Its visual brightness varies very slightly.
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