A powerful cosmic particle accelerator has been pinpointed in the Crab Nebula: a doughnut-shaped magnetic field surrounding the stellar corpse at the nebula's heart. The finding is based on a tricky measurement showing that high-energy radiation near the star is polarised, with its electric field lining up neatly with the star's spin axis.
The Crab Nebula is the expanding remnant of a supernova that was observed by Chinese and Arab astronomers in 1054 CE. When the star exploded, it left behind a dense corpse called a pulsar.
The pulsar spins about 30 times per second, but is gradually slowing down as it emits a wind of particles and electromagnetic fields.
Some of these particles – mainly electrons – emit high-energy radiation, in the form of X-rays and gamma rays, when they are accelerated by magnetic fields in the region. But it has been unclear where this acceleration is taking place.
Now, researchers led by Tony Dean of the University of Southampton in the UK say it is occurring quite close to the pulsar.
The Crab Nebula is the expanding remnant of a supernova that was observed by Chinese and Arab astronomers in 1054 CE. When the star exploded, it left behind a dense corpse called a pulsar.
The pulsar spins about 30 times per second, but is gradually slowing down as it emits a wind of particles and electromagnetic fields.
Some of these particles – mainly electrons – emit high-energy radiation, in the form of X-rays and gamma rays, when they are accelerated by magnetic fields in the region. But it has been unclear where this acceleration is taking place.
Now, researchers led by Tony Dean of the University of Southampton in the UK say it is occurring quite close to the pulsar.
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