A massive star ends its life in a cataclysmic supernova explosion. The aftermath is a cloud of hot gas called a supernova remnant (SNR) and a pulsar could also be formed at the centre. With ultra strong magnetic field and rapid rotation, a pulsar can accelerate particles to high energies. The interaction of these particles with the surrounding supernova debris can create a pulsar wind nebula (PWN) with complex structure.

The Cosmic Hand, MSH 15-52, is a remarkable PWN spanning across 150 light-years and is powered by pulsar B1509-58 formed about two thousand years ago. The X-ray emission of the nebula shows an uncanny resemblance to a human hand, complete with a palm, a thumb, and fingers. Zhang et al. obtained high-resolution radio image of MSH 15-52 with the Australia Telescope Compact Array (ATCA). They discover surprisingly distinct structure in the radio band. The strong X-ray jet, X-ray arcs, and fingers all show no radio emission. Instead, the ATCA data reveal a complex network of intricate filaments with a highly ordered magnetic field that follows the the filamentary structure. These could be resulting from complex interplay between the pulsar particles and the surrounding SNR, and the radio and X-ray emission could correspond to two populations of particles, with the most energetic ones leaking out from the jet and fingers.

The image above shows a composite view of the Cosmic Hand. The radio data are shown in red, X-rays are shown in blue, orange, and yellow, and an optical image of hydrogen gas is in gold. The vectors indicate the directions of the Nebula’s Magnetic Field. (Credit: X-ray: NASA/CXC/Univ. of Hong Kong/S. Zhang et al.; Radio: ATNF/CSIRO/ATCA; H-alpha: UK STFC/Royal Observatory Edinburgh; Image Processing: NASA/CXC/SAO/N. Wolk) More images can be found on the Chandra website.