Neutron star and magnetic field. Animation clip 5 of 11 showing the magnetic field lines blue associated with a rapidly rotating neutron star, and its jets of radiation purple that are seen on Earth as the signal from a pulsar. Neutron stars are immensely dense stellar core remnants, formed after a massive star runs out of hydrogen fuel and its core collapses. This animation is part of a sequence showing the role neutron stars can play in causing gamma_ray bursts GRBs. Later clips in this sequence K003/2670_2660 show the process of neutron star merger in detail including the changes in their magnetic fields, as modelled by the Damiana supercomputer at Germany磗 Max Planck Institute for Gravitational Physics.