Observations of energetic ions from comet giacobini-zinner

During the encounter with comet Giacobini-Zinner, the energetic particle anisotropy spectrometer on the International Cometary Explorer spacecraft observed large fluxes of energetic ions, believed to result principally from ionization of the cometary atmosphere followed by pickup and acceleration by the ambient flow of the solar wind. These heavy cometary ions were observed from approximately 1 day before closest approach to about 2(1/2) days afterward. Three regimes of differing ion characteristics have been identified. An outer region with a scale of approximately 10(6) kilometers contains variable fluxes of antisolar-streaming pick-up ions in the undisturbed solar wind. In the middle region, of approximately 10(5) kilometers, fluxes have less large-scale variability and broader angular and energy distributions. This region is separated from the outer zone by a sharp transition. The inner region has a scale of approximately 10(4) kilometers and is characterized by reduced fluxes and complex angular distributions.     

Dense astrophysical plasmas

Degenerate bodies composed primarily of dense hydrogen and helium plasmas range from giant planets to the so far hypothetical brown dwarfs. More massive objects begin their lives as nondegenerate stars and may end as white dwarfs, composed primarily of carbon and oxygen, or as neutron stars, with solid crusts of iron or heavier elements and cores of neutron matter. The physical properties of dense plasmas that are necessary to construct theoretical models of such degenerate stars include the equation of state, transport properties, and nuclear reaction rates.