Webb Photographs the Rarely-Seen Moments Just Before a Supernova

Mar 14, 2023

A large, bright star shines from the centre with smaller stars scattered throughout the image. A clumpy cloud of material surrounds the central star, with more material above and below than on the sides, in some places allowing background stars to peek through. The cloud material is yellow closer to the star.

The James Webb Space Telescope has captured what is known as a Wolf-Rayet star, the brief phase that comes just before it goes supernova. Due to how short the time is that a star is in this phase, it is one of the rarest astronomical observations.

According to the European Space Agency (ESA), this capture of a Wolf-Rayet star was one of the first observations made by Webb, although the photos are only being released today. The photo is specifically of a star known as WR 124 and shows what the ESA calls “unprecedented detail” of the celestial object that lies 15,000 light-years away from Earth in the constellation Sagittarius.

“Massive stars race through their life cycles, and not all of them go through a brief Wolf-Rayet phase before becoming a supernova, making Webb’s detailed observations valuable to astronomers,” the ESA explains.

“Wolf-Rayet stars are in the process of casting off their outer layers, resulting in their characteristic halos of gas and dust. The star WR 124 is 30 times the mass of the Sun and has shed 10 Suns-worth of material — so far. As the ejected gas moves away from the star and cools, cosmic dust forms and glows in the infrared light detectable by Webb.”

The ESA has shared two images of the Wolf-Rayet star: one shows just the mid-infrared image (captured by Webb’s MIRI camera) as shown below, while the other shows a near-infrared image (captured by Webb’s NIRCam) combined with the MIRI into a composite, as seen above.

Wolf-Rayet 124 (WR 124) — A large, bright cloud of yellow, pink, and purple surrounds a white star that looks like a tiny snowflake. A few small blue background stars are visible. Dark gaps break up the cloud, and small bright areas on the upper and lower left appear like schools of tadpoles swimming toward the central star. There are areas where clumps of bright hot material are being blown outward by the star, like hair streaming out behind someone standing in front of a fan.

The background stars and galaxies in the image provide a sense of scale to the colored gas and dust that are visible in the photo — it’s being ejected over an area 10 light-years across. Speaking of dust, the ESA explains that this matter is very important to the way the Universe works, from how stars ar formed to how it gathers together to form planets.

“The origin of cosmic dust that can survive a supernova blast and contribute to the Universe’s overall ‘dust budget’ is of great interest to astronomers,” the ESA says.

“Despite the many essential roles that dust plays, there is still more dust in the Universe than astronomers’ current dust-formation theories can explain. The Universe is operating with a dust budget surplus.”

As a showcase for just how advanced Webb’s imaging capability is, the ESA has also uploaded a photo of WR 124 as captured by the Hubble Space Telescope in 2015: