NASA’s James Webb Space Telescope has captured unprecedented new views of nebula PMR 1 — nicknamed the “Exposed Cranium” for its striking resemblance to a brain inside a transparent skull — offering fresh insight into the chaotic final stages of a dying star’s life.
Released Wednesday, the images combine near-infrared data from Webb’s NIRCam and mid-infrared observations from MIRI, highlighting distinct regions that trace different phases of the nebula’s evolution. An outer shell of mostly hydrogen gas was blown off early in the star’s decline, while the inner, more structured cloud contains a richer mix of elements. A prominent dark vertical lane slices through the center, dividing the nebula into left and right “hemispheres” — a feature that becomes even more pronounced in Webb’s high-resolution views.
The dark lane likely results from an energetic outburst or bipolar outflow from the central star, with twin jets erupting in opposite directions. Evidence is clearest in the MIRI image at the nebula’s top, where inner gas appears to be violently ejected outward. These outflows are common in the late stages of stellar evolution, as stars exhaust their fuel and shed outer layers in dynamic, relatively rapid processes (on cosmic timescales).
First glimpsed in infrared more than a decade ago by NASA’s now-retired Spitzer Space Telescope, PMR 1 remained little-studied until Webb’s advanced instruments revealed the intricate details that amplify its brain-like appearance. The nebula surrounds a star nearing the end of its life cycle — its ultimate fate depends on mass. A sufficiently massive star will end in a supernova explosion; a Sun-like star will continue shedding layers until only a dense white dwarf core remains, cooling slowly over billions of years.
Webb’s observations capture a precise moment in this decline, providing astronomers with critical data on how stars expel material and shape their surrounding nebulae. The telescope continues to solve mysteries across the cosmos, from our solar system to distant exoplanets and the universe’s origins.
Webb is the world’s premier space science observatory, an international collaboration led by NASA with partners ESA (European Space Agency) and CSA (Canadian Space Agency).
