An astrophysicist has uncovered the explanation behind the "zebra" pattern observed in the Crab Nebula.

The Crab Nebula is composed of material that was once part of a star. These were its outer layers. Estimates suggest that the total mass of the cloud is about 4.6 times that of the Sun. At its center lies a neutron star—a tremendously compressed, ultra-dense clump of subatomic particles. With a mere diameter of 25 kilometers, it contains a mass of 1.4 times that of the Sun. This is the "collapsed" core of the progenitor star. Thus, the original star "weighed" approximately six times more than our Sun.

This large, blue, and hot star "lived" only a short time in cosmic terms—around 10 to 20 million years. Eventually, its core ran out of fuel for nuclear reactions. The core began to collapse under its own gravity, while the mantle expanded, ultimately ejecting it violently into space. At this moment, an extraordinarily bright flash occurred, visible throughout the galaxy. This is what is known as a supernova explosion.

The flash was observed from Earth in 1054, with records in historical chronicles. However, it actually occurred much earlier: 7,500 years ago. The reason is that the Crab Nebula is located 6,500 light-years away from us, meaning it takes light from it 6,500 years to reach Earth.

The former core, that is, the neutron star, was officially discovered in 1968 and cataloged as PSR B0531+21. It spins extremely rapidly, completing around thirty rotations every second. Additionally, strong emissions in various ranges emanate from both of its poles. Since the star's axis of rotation "wobbles," similar to a spinning top, the poles alternately appear and disappear from the observer's view. This results in the star "flashing" or "pulsating." Thus, neutron stars have earned the nickname pulsars.

Professor Mikhail Medvedev from the University of Kansas (USA) mentioned in his article for Physical Review Letters that an unusual feature was noticed while observing the Crab Nebula through a radio telescope back in 2007.

According to the researcher, the typical radio emissions from neutron stars occur across a broad frequency range, but in the case of the "Crab" pulsar, a unique high-frequency component is added: ranging from five to 30 gigahertz. This falls into the microwave spectrum. When such different waves overlap, the resulting emission pattern creates the "zebra pattern" that remained unexplained for over fifteen years.

Medvedev suggested that a strong magnetic field from this still very young pulsar is involved. It seems to create relatively dense plasma regions in the star's immediate vicinity, which act as obstacles for the radio emissions, partially reflecting them.

It is this reflection that leads to the high-frequency signal, the researcher clarified. He hopes that future observations of the "zebra" in the Crab Nebula will yield more insights into this plasma "barrier" constructed by the star's magnetosphere.