Cosmic fingerprint around Wolf Rayet 140 revealed by James Webb Telescope

Shells of cosmic dust created by the interaction of binary stars appear like tree rings around Wolf-Rayet 140. Credit: NASA, ESA, CSA, STScI, JPL-Caltech

October 12, 2022

The James Webb Space Telescope of NASA captured this image which shows at least 17 concentric dust rings coming from a pair of stars orbiting one another. The system is called Wolf-Rayet 140 because one of the stars is a Wolf-Rayet star and is little over 5,000 light-years away from Earth. One of the known star types with the highest mass is an O-type star. Each ring was formed when the stellar winds from the two stars clashed as they drew near to one another, compressing the gas and generating dust. Each orbit generates a ring just once every 7.93 years.

An O-type star that was born at least 25 times as massive as our Sun and is on the verge of extinction is referred to as a Wolf-Rayet star. The star will then either undergo a supernova explosion or disintegrate into a black hole. The intervals between the episodes of dust production are what create the recognizable ring pattern. A pinwheel pattern is frequently created when the stars in a Wolf-Rayet pair are sufficiently near to one another and have circular orbits. The rings of WR 140 are also known as shells because they are not perfectly circular and are wider and thicker than they seem in the photograph.

Instead of producing a precise "bullseye" pattern, the rings have a patchy appearance that is brighter in some places and nearly unnoticeable in others. This is due to the varied nature of dust creation as the stars come closer to one another and the fact that Webb is not directly observing the stars' orbital plane because he is viewing the system from an angle. The brilliant glow visible at two o'clock is produced by one of the densest locations of dust generation.

The Mid-Infrared Instrument (MIRI), which is currently under the control of the organization's Goddard Space Flight Center, captured the image. The infrared spectrum of light, which is emitted by warm things but is invisible to the human eye, is detected by Webb's scientific equipment. Due to its ability to detect longer infrared wavelengths than the other three Webb instruments, MIRI is frequently able to identify colder objects, such as these dust rings.

Hydrogen, the most prevalent element in stars, cannot produce dust on its own. However, Wolf-Rayet stars in their advanced stages have expelled all of their hydrogen, leading them to eject elements that are generally found far inside a star, such as carbon, which can produce dust. The dust produced by WR 140 is most likely composed of polycyclic aromatic hydrocarbons (PAHs), a class of chemical substances rich in carbon that are expected to increase the carbon content of the entire universe, according to data from MIRI's Medium Resolution Spectrometer (MRS).

This image compares the Sun, upper left, to the two stars that make up the Wolf-Rayet 140, or WR 140, binary system. The companion of the O-type star weighs around 10 times as much as the Sun, whereas the O-type star itself is about 30 times as massive. Some of the largest and brightest stars in the universe are O-type stars. Compared to stars like our Sun, which have a lifespan of roughly 10 billion years, they have a relatively brief lifespan of no more than about 10 million years.

Credit: NASA/JPL-Caltech, Source: NASA/JPL

This animation looks down from above the orbital plane to depict the spiraling creation of dust in the binary star system WR 140. A Wolf-Rayet star — the dense core of an aging massive star — and an O-type star orbit one another, their stellar winds colliding as they get close. The intermixed stellar material blows back past the O star, forming dust as it cools. Credits: VIDEO: NASA, ESA, Joseph Olmsted (STScI)