| Crab Nebula: supernova remnant and pulsar (radio view) | 29/08/1999 | ||
 |
The
Crab Nebula is the remnant of a supernova explosion that was seen on Earth
in 1054 AD. It is 6000 light years from Earth. At the center of the bright
nebula is a rapidly spinning neutron star, or pulsar that emits pulses of
radiation 30 times a second. Constellation: Taurus Optical view X-ray view Infrared view |
||
| Go to full text | |||
 |
|||
 |
|||
| Image Credit: VLA, NRAO. | |||
|
|
|||
| The
Crab Nebula consists of a pulsar, a rapidly rotating neutron star at the
center, surrounded by a bright diffuse nebula. The nebula, which is about
six light years across, is expanding outward at 3 million miles per hour.
The filamentary system visible in the optical images is near the outer boundary
of this expansion. Both the nebula and the pulsar are bright sources of
radiation in all wavelengths.
The radiation we observe from the Crab Nebula is produced mainly by high-energy particles accelerated by the neutron star. These energetic particles, which near the neutron star are thought to include anti-matter positrons as well as electrons, spiral around magnetic field lines in the nebula and give off radiation by the "synchrotron" process. |
|
Radio waves come from the lowest energy electrons. They can travel the greatest distance and define the full extent of the nebula. The Crab's central pulsar was discovered in 1968 by radio astronomers. The pulsar was then identified as a source of periodic optical and X-ray radiation. The periodic flashes of radiation are caused by a beam from the rapidly rotating neutron star. | |
| Return to top of page | |||