Two heads are better than one in the latest images from NASA’s James Webb Space Telescope, which reveal new detail in a mysterious, little-studied nebula surrounding a dying star.
Nebula PMR 1 is a cloud of gas and dust that bears an uncanny resemblance to a brain in a transparent skull, inspiring its nickname, the “Exposed Cranium” nebula. Webb captured its unusual features in both near- and mid-infrared light. The nebula was first revealed in infrared light by a predecessor to Webb, NASA’s now-retired Spitzer Space Telescope, more than a decade ago. Webb’s advanced instruments show detail that enhances the nebula’s brain-like appearance.
The differences in what Webb’s infrared instruments reveal and conceal within the PMR 1 “Exposed Cranium” nebula is apparent in this side-by-side view. More stars and background galaxies shine through NIRCam’s view, while cosmic dust glows more prominently in MIRI’s mid-infrared.
Image: NASA, ESA, CSA, STScI; Image Processing: Joseph DePasquale (STScI)
The nebula appears to have distinct regions that capture different phases of its evolution — an outer shell of gas that was blown off first and consists mostly of hydrogen, and an inner cloud with more structure that contains a mix of different gases. Both Webb’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument) show a distinctive dark lane running vertically through the middle of the nebula that defines its brain-like look of left and right hemispheres. Webb’s resolution shows that this lane could be related to an outburst or outflow from the central star, which typically occurs as twin jets burst out in opposite directions. Evidence for this is particularly notable at the top of the nebula in Webb’s MIRI image, where it looks like the inner gas is being ejected outward.
While there is still much to be understood about this nebula, it’s clear that it is being created by a star near the end of its fuel-burning “life.” In their end stages, stars expel their outer layers. It’s a dynamic and fairly fast process, in cosmic terms. Webb has captured a moment in this star’s decline. What ultimately happens will depend on the mass of the star, which is yet to be determined. If it’s massive enough, it will explode in a supernova. A less massive Sun-like star will continue to shed layers until only its core remains as a dense white dwarf, which will cool off over eons.
The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).
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