A dark vertical lane slices through the center of PMR 1, splitting it into two lobes that, from a distance, look unsettlingly like a human brain. That single structural detail — visible in new images released on Feb. 25, 2026 — has become the key to understanding what the James Webb Space Telescope is actually showing scientists about this dying star’s final chapters.
PMR 1, nicknamed the “Exposed Cranium” nebula, sits roughly 5,000 light-years from Earth in the constellation Vela. It is a planetary nebula: an expanding shell of ionized gas and dust thrown off by a star that has exhausted its nuclear fuel. The object was first detected in 2014 by the Spitzer Space Telescope but received little scientific attention until now.
Webb captured the nebula using two separate instruments simultaneously, and the gap between what each one sees tells a story neither could tell alone.
Two Instruments, Two Realities
The Near-Infrared Camera (NIRCam) image, on the left, shows the nebula’s outer bubble edged in bright white, with inner clouds glowing orange. The dark central lane cuts cleanly through the structure, reinforcing the brain-like appearance. Background stars and distant galaxies are visible through the nebula’s outer shell — a reminder that near-infrared light passes through material that blocks other wavelengths.
The Mid-Infrared Instrument (MIRI) image tells a different story. The outer bubble shifts to bluish-purple tones, the inner clouds appear thicker and more layered, and the dark lane nearly disappears — obscured by dust and gas that mid-infrared light cannot fully penetrate. But according to the announcement, the MIRI view reveals something the NIRCam misses: that dark streak connects directly to twin eruptions of gas firing outward from the top and bottom of the nebula.
That connection was invisible before. It required looking at the same object in two different wavelength ranges to find it.
What the Layers Record
The structure of PMR 1 preserves a timeline. The outer shell is composed primarily of hydrogen gas expelled earlier in the star’s life. The denser inner clouds — a mixture of gases and dust — came later, shed more recently as the star continued to lose mass. Each layer is, in effect, an archive of a different moment in the star’s decline.
What happens next depends entirely on the central star’s mass. It will either accumulate enough pressure to trigger a supernova explosion, or it will continue shedding material until only a dense, collapsed remnant remains — what astronomers call a white dwarf. The report does not specify which outcome current data favors.
The colorful cloud described as resembling a brain inside a transparent skull earned its informal name precisely because of that dark dividing lane — the same feature that now turns out to be structurally tied to the nebula’s most energetic outflows. The detail that made it look like a brain is also the detail that explains how the star is dying.
Photo by Frode Myklebust on Unsplash
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