Scientists probe the dynamic Cocoon of a nearby pulsar

A pulsar wind nebula is formed after a massive star dies. The collapsed core becomes a pulsar, which emits a powerful wind made of high-energy charged particles. This wind collides with surrounding debris, creating a glowing cloud called a pulsar wind nebula.

Vela X is powered by the Vela pulsar, which sits in the supernova remnant G263.9–3.3. A long structure called the Cocoon lies in Vela X. The Cocoon is a narrow stream of energetic particles extending away from the pulsar towards the south-southwest. However, scientists noticed that the Cocoon emits radiation in both radio waves and X-rays, which appear in different locations. This was surprising to astronomers because the radiation usually overlaps in similar objects.

A possible explanation is that the Cocoon formed when a reverse shock from the supernova remnant traveled back towards the nebula. This caused a distortion to the nebula, creating the cocoon structure.

To further understand this phenomenon, scientists used the ATCA and discovered in very detailed images that the Cocoon contained large curved filaments. Inside the larger filaments, small irregular wisps were seen, suggesting highly turbulent and unstable plasma motion. New data has also shown that the filaments were highly polarized, indicating ordered magnetic field lines.

Further observations would help scientists measure the local magnetic field strength and increasen their understanding of how the Cocoon formed.