A transparent skull floating in the void of space: this is the astonishing vision offered by the James Webb Space Telescope, which captured a nebula evoking a brain imprisoned in its cranial vault. This singular image projects us into the heart of the final moments of a star, revealing the beauty and diversity of celestial events in a new light.
Thanks to its state-of-the-art instruments, the James Webb Space Telescope examined this object with remarkable precision. Located about 5,000 light-years away in the constellation of Vela, it reveals fine details previously invisible. The near-infrared and mid-infrared images clearly show the internal and external structures, as if a cosmic veil had been lifted.
On the left, the near-infrared image of the Exposed Skull Nebula, and on the right, the mid-infrared version. Many distant galaxies populate the background.
Credit: NASA/ESA/CSA/STScI ; Image processing: Joseph DePasquale (STScI). Officially named PMR 1, this nebula was spotted in the late 1990s by astronomers using the UK Schmidt Telescope in Australia. Its nickname "Exposed Skull" was given following observations by the
Spitzer Space Telescope in 2013, due to its silhouette reminiscent of a human head. This characteristic naturally led scientists to scrutinize its formation and evolution.
Recent information provided by JWST indicates that the outer shell, primarily composed of hydrogen, was ejected first by the central star. This structure then gradually cooled, and at the same time, the ionized gases expelled later inside began to draw detailed patterns. These internal shapes, reminiscent of brain convolutions, accentuate the object's unusual appearance.
A well-defined separation in the center of the nebula seems to divide this brain-like mass into two hemispheres, creating left-right symmetry. This notch could originate from polar jets emitted by the dying star, as shown in the mid-infrared image where gases shoot through the envelope. If this hypothesis is confirmed, it would provide clues about the star's orientation relative to the nebula.
The precise nature of the central star remains uncertain. At the time of its discovery, its emission signals pointed toward a Wolf-Rayet star, a massive and unstable star. For now, no definitive proof has been gathered, leaving the door open to the hypothesis of a planetary nebula born from a star similar to the Sun at the end of its life.