One of the first observations made in June 2022 by NASA’s James Webb Space Telescope was the rare sighting of the Wolf-Rayet star, one of the brightest, largest, and shortest-lived stars. Webb shows the star WR 124 in unprecedented detail thanks to powerful infrared instruments. The star is located 15,000 light-years away in the constellation Sagittarius.

Massive stars go through their life cycles, and only a few go through a brief Wolf-Rayet stage before turning supernova, making Webb’s detailed observations of this rare stage valuable to astronomers. Wolf-Rayet stars are in the process of shedding their outer layers resulting in characteristic halos of gas and dust. The star WR 124 has 30 times the mass of the Sun and has so far ejected 10 times as much material as the Sun. As the ejected gas moves away from the star and cools, cosmic dust forms and glows in the infrared light detected by Webb.

The origin of cosmic dust, which can survive a supernova explosion and contribute to the overall “dust budget” of the universe, is of great interest to astronomers for several reasons. Dust is an integral part of the workings of the universe: It protects forming stars, clumps together to help form planets, and serves as a platform for molecules to form and stick together, including the building blocks of life on Earth. Despite the many important roles dust plays, there is still more dust in the universe than astronomers’ current theories of dust formation can explain. The universe is working on a budget surplus.

Webb opens up new possibilities for studying the details of cosmic dust best observed in the infrared wavelength range. The Webb Near Infrared Camera (NIRCam) stabilizes the brightness of WR 124’s stellar core and knotty details in the fainter surrounding gas. The telescope’s Mid-Infrared Instrument (MIRI) shows the complex structure of the gas-dust nebula, which is made up of ejected material currently surrounding the star. Before Webb, dust-loving astronomers didn’t have enough detailed information to investigate dust formation in environments like WR 124 and whether dust grains were large and abundant enough to survive a supernova and contribute significantly to the overall dust budget. Now these questions can be explored with real data.

Stars like WR 124 also serve as analogues to help astronomers understand a pivotal period in the early history of the universe. Such dying stars first seeded the young universe with heavy elements processed in their cores – elements common today, including on Earth today.