| Astrophysics (Index) | About |
An HZE ion (or HZE particle) is a metal ion lacking three or more electrons, that is traveling at relativistic speed. "HZE" stands for high atomic number (Z) and kinetic energy. They are necessarily metals, i.e., with a Z of 3 or higher. They include any metal that is fully ionized, and often "HZE" is taken to imply full ionization, which is generally the case for particles moving at such speed. Some cosmic rays are HZE ions (HZE cosmic rays), as are some solar energetic particles (SEPs). Examples are fully ionized carbon, oxygen and iron. From a health standpoint, HZE ions constitute a dangerous portion of cosmic rays and SEPs, and are a major concern regarding human space travel.