Windy Energy

18 Feb 2012

At ... we learn that a paper in Nature claims the extraordinarily high energy emissions at the heart of the Crab Nebula come not from a pulsar at its core but from wind. The pulsar is what is left from after a large supernovae event, theorised as being a neutron star that spins 30 times a second - and appears to pulse in the process. Until now scientists have assumed the energy comes from the pulsar - as it arrives in bursts. However, it seems the energy does not come from the pulsar after all but to a point somewhat near it and this has led to an attempt to explain it as wind. The wind also has an electro-magnetic origin.

At and at under the headline, Plasma torn apart: discovery hints at origin of phenomena like solar flares and is derived from research by Caltech scientists (published in Nature, Feb 16th) and is basically about magnetic reconnection during a solar flaring event. Large pieces of plasma erupt from the Sun and using high speed cameras to look at the jets of plasma in the laboratory they claim to reproduce what happens in the sky - but did they? The experiment required 200 million watts of power to produce jets of 20,000 degrees Kelvin and carry a current of 100,000 amps. At this point the camera was applied, snapshots of less than a microsecond (one millionth of a second). The technology is breathtaking but they found a cordscrew shape develop in the jets that grew exponentially and extremely fast, forming coils with ripples  that appeared just before they broke - a moment before magnetic reconnection, in what is known as a Rayleigh Taylor instability. As the coiled plasma expands it accelerates outwards, the plasma trying to swap places with the trailing vacuum by forming ripples etc.