Astronomers utilizing the NASA/ESA/CSA James Webb Space Telescope have identified two stars responsible for generating carbon-rich dust just 5,000 light-years from Earth, within the Milky Way galaxy. The massive stars in the Wolf-Rayet 140 system, which orbit each other in elongated paths, create this dust through colliding stellar winds.
During their closest approach every eight years, the stars produce a new shell of dust that expands outward, potentially contributing to star formation elsewhere in the galaxy. Webb's observations have revealed 17 dust shells emitting mid-infrared light, all expanding at consistent velocities.
Emma Lieb, lead author of the study and a doctoral student at the University of Denver, noted, "The telescope confirmed that these dust shells are real, and its data also showed that they are moving outward at consistent velocities, revealing visible changes over incredibly short periods of time." Each shell is moving away from the stars at speeds exceeding 2,600 kilometers per second, nearly 1% the speed of light.
In addition, the mid-infrared images from Webb detected dust shells that have persisted for over 130 years. Researchers speculate that the stars may produce tens of thousands of dust shells over hundreds of thousands of years. Ryan Lau, an astronomer at NSF NOIRLab, emphasized the importance of mid-infrared observations, stating, "With these incredible new details, the telescope is also allowing us to study exactly when the stars are forming dust — almost to the day."
The future of the Wolf-Rayet stars remains uncertain. The more massive star is nearing the end of its life and may either explode as a supernova or collapse into a black hole, potentially preserving the dust shells. This research sheds light on the origins of carbon-rich dust in the universe, which is crucial for forming rocky planets and solar systems.
The findings were published in the Astrophysical Journal Letters and presented at the 245th meeting of the American Astronomical Society in National Harbor, Maryland.