process has causal agent star X-ray stellar radiation A stellar radiation process during which penetrating electromagnetic radiation is emitted by high-energy electrons as they fall into a lower state of energy. Ambiguity exists in the definition of x-rays and their differentiation from gamma rays. Photons with sufficient energy to be classified as x-rays may be emitted by other processes than electrons falling to lower energy states. Most x-rays have wavelengths ranging from 0.01 to 10 nanometers, corresponding to frequencies in the range of 30 petahertz to 30 exahertz and energies in the range of 100 eV to 100 keV. environmental_hazards envoAstro ENVO X-ray solar radiation x ray stellar radiation ionizing stellar radiation X-ray radiation requires discussion