James Webb Telescope Captures Cosmic Dust ‘Fingerprint’
A fascinating new image captured by the James Webb Space Telescope (JWST) captures 17 dust rings that resemble a fingerprint created by a rare type of star.
A Wolf-Rayet star is hundreds of thousands of times brighter and much hotter than Earth’s sun. Wolf-Rayet stars represent the final stage in the evolution of giant stars before they explode in supernovas and turn into black holes.
This particular Wolf-Rayet, known as WR140, has a smaller star orbiting it and as the pair come close together the streams of gas that emanate from each of them collide, compressing the gas and forming dust.
The photo and subsequent research is the first time scientists have found evidence of starlight moving visible matter beyond our solar system.
The stars’ orbit brings them together about once every eight years, with the dust loops marking the passage of time.
“These two stars orbit each other in very elliptical orbits,” Yinuo Han, an astronomer at Cambridge University in the U.K. and lead author on one of the new studies about WR140 tells Space.
“Every eight years they get close to each other and produce dust.” It is this dust that is rippling away from the star in the image; the time when the stars are more distant creates the space between the rings.
“We’re looking at over a century of dust production from this system,” says Ryan Lau, an astronomer at the National Science Foundation’s NOIRLab.
“The image also illustrates just how sensitive JWST is. Before, we were only able to see two dust rings, using ground-based telescopes. Now we see at least 17 of them.”
Webb’s Mid-INfrared Instrument (MIRI) is uniquely qualified to study the dust rings, which researchers call shells, because it sees in infrared light, a range of wavelengths invisible to the human eye.
MIRI detects the longest infrared wavelengths, which means it can often see cooler objects – including the dust rings – than Webb’s other instruments can. MIRI’s spectrometer also revealed the composition of the dust, formed mostly from material ejected by a type of star known as a Wolf-Rayet star.
Gas into Dust
Transforming gas into dust requires specific conditions and ingredients. The most common element found in stars, hydrogen, can’t form dust on its own. But because Wolf-Rayet stars shed so much mass, they also eject more complex elements typically found deep in a star’s interior, including carbon.
The heavy elements in the wind cool as they travel into space and are then compressed where the winds from both stars meet.
Some other Wolf-Rayet systems form dust, but none is known to make rings as Wolf-Rayet 140 does. The unique ring pattern forms because the orbit of the Wolf-Rayet star in WR 140 is elongated, not circular. Only when the stars come close together — about the same distance between Earth and the Sun — and their winds collide is the gas under sufficient pressure to form dust. With circular orbits, Wolf-Rayet binaries can produce dust continuously.
