A Supernova's Heart Beats in Jets express
The James Webb Space Telescope JWST has peered into the heart of supernova remnant SNR 0540-69.3 — what remains after a massive star died in a neighboring galaxy. Inside, amid the flying debris, astronomers saw a clear pattern: glowing clumps and voids arranged in a symmetric design. One half looks like a mirror image of the other, but rotated by 189 degrees. Such point symmetry is no accident; it's a trace of powerful jets that plowed through the material during the explosion.
The 'jittering jets' mechanism paints a picture of a chaotic yet orderly process. When a star's core collapses into a neutron star, it doesn't settle down immediately. The newborn object, spinning and wobbling, shoots out narrow beams of particles — jets. These don't fire in one direction; they change direction like a garden hose that slips from your grip. Each pair of jets carves its own channels and cavities into the expanding material. In SNR 0540-69.3, at least three such pairs have been found: one created the main cavities, another made 'nozzles' at a wide angle, and a third may have added asymmetry.
This discovery connects two worlds: the explosions of massive stars and the formation of planetary nebulae. Both share the same signature left by jets. Both show symmetry, cavities, and knots. So nature uses a similar tool regardless of scale. And the Hubble telescope never dreamed of such clarity.
Original abstract
as written by the authors arXiv:2606.28286
We examine published JWST observations of the core-collapse supernova (CCSN) remnant SNR 0540-69.3 and identify a point-symmetric morphology in its inner ejecta. Within the framework of the jittering jets explosion mechanism (JJEM), we interpret this morphology as evidence that the ejecta were shaped by two, and likely three or more, pairs of jets during the explosion process. Both visual inspection and a recently developed quantitative symmetry-identification method for astrophysical imaging reveal an approximate rotational symmetry between the northeastern redshifted ejecta and the southwestern blueshifted ejecta. Each side contains clumps (knots) surrounding a previously identified cavity, with the best quantitative correspondence obtained for a rotation of 189{\deg}. We further identify a symmetry center that is offset from the current pulsar position, strengthening an earlier claim for a pulsar kick. We interpret the pair of cavities and their surrounding clumpy structures as having been shaped by multiple jet-launching episodes. In addition, we identify a pair of opposing nozzles at a large angle to the cavities, which we attribute to another jet pair. Guided by the similarities to point-symmetric planetary nebulae shaped by jets and by recent three-dimensional hydrodynamical simulations of the JJEM, we conclude that the inner ejecta were shaped by at least three jet pairs launched by the neutron star after it acquired its kick velocity, consistent with the JJEM.
The pulsar at the center of SNR 0540-69.3 is a neutron star the size of a city but with a mass of one and a half Suns. It spins 20 times per second, and its 'kick' at birth was so strong that the center of the explosion was left behind.
In Robert Wilson's novel 'Spin,' neutron stars are used as interstellar beacons — and here nature itself has set up 'signposts' made of jets so we can read the story of the explosion.