When the stars in Wolf-Rayet 140 approach one another in their elliptical orbit, their stellar winds collide, compressing material and forming carbon-rich dust. Webb's observations revealed 17 concentric dust shells, visible in mid-infrared light, expanding outward at regular intervals.
"The telescope not only confirmed that these dust shells are real, its data also showed that the dust shells are moving outward at consistent velocities, revealing visible changes over incredibly short periods of time," said Emma Lieb, lead author of the new study and a doctoral student at the University of Denver in Colorado.
These dust shells, racing away from the stars at over 1,600 miles per second (2,600 kilometers per second), move at nearly 1% of the speed of light. "We are used to thinking about events in space taking place slowly, over millions or billions of years," added Jennifer Hoffman, a co-author and professor at the University of Denver. "In this system, the observatory is showing that the dust shells are expanding from one year to the next."
Every eight years, as the stars reach the closest point in their orbit, their winds generate new dust over several months. Webb's mid-infrared capabilities also revealed variations in dust formation, such as darker regions in its images.
The mid-infrared images captured by Webb detected dust shells that have existed for more than 130 years. While older shells have dimmed and become undetectable, researchers estimate that the stars will produce tens of thousands of such shells over hundreds of thousands of years.
"Mid-infrared observations are absolutely crucial for this analysis, since the dust in this system is fairly cool. Near-infrared and visible light would only show the shells that are closest to the star," explained Ryan Lau, a co-author and astronomer at NSF NOIRLab in Tucson, Arizona. "With these incredible new details, the telescope is also allowing us to study exactly when the stars are forming dust - almost to the day."
Close examination of the dust shells revealed non-uniform distribution. Some areas showed "piled up" amorphous clouds the size of our solar system, while other particles were dispersed freely. Despite these variations, all the dust, which is carbon-rich, travels at the same speed. Each particle is as small as one-hundredth the width of a human hair.
"A major question in astronomy is, where does all the dust in the universe come from?" said Lau. "If carbon-rich dust like this survives, it could help us begin to answer that question."
Jennifer Hoffman added, "We know carbon is necessary for the formation of rocky planets and solar systems like ours. It's exciting to get a glimpse into how binary star systems not only create carbon-rich dust, but also propel it into our galactic neighborhood."
The study's findings were published in the Astrophysical Journal Letters and presented during the 245th meeting of the American Astronomical Society in National Harbor, Maryland.
Related Links
Webb Telescope
Stellar Chemistry, The Universe And All Within It
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