Astroparticle Physics

16 Glossary 307A quantity is conserved, if it does not change in the course of areaction between particles. Conserved quantities are, for example,electric charge, energy, and momentum.A group of stars that produce in projection a shape often namedafter mythological characters or animals.An alternative process to X-ray emission during the de-excitationof an excited atom or an excited nucleus. If the excitation energyof the atomic shell is transferred to an atomic electron and if thiselectron is liberated from the atom, this electron is called an Augerelectron. If the excitation energy of a nucleus is transferred to anatomic electron of the K, L, orM shell, this process is called internalconversion. Auger electron emission or emission of characteristicX rays is often a consequence of internal conversion.A very hot outer layer of the Sun’s atmosphere consisting of highlydiffused ionized gas and extending into interplanetary space. Thehot gas in the solar corona forms the solar wind.European gamma-ray satellite started in 1975.Standard composition of elements in the universe as determinedfrom terrestrial, solar, and extrasolar matter.CBR; nearly isotropic blackbody radiation originating from the BigBang (‘echo of the Big Bang’). The cosmic background radiationhas now a temperature of 2.7 K.Nuclear and subatomic particles moving through space at velocitiesclose to the speed of light. Cosmic rays originate from stars and,in particular, from supernova explosions. The origin of the highestenergycosmic rays is an unsolved problem.One-dimensional defects, which might have been created in theearly universe.Topological defect which involves a kind of twisting of the fabricof space-time.The branch of particle physics and astronomy that tries to dig outresults on elementary particles and cosmology from experimentalevidence obtained from data about the early universe.The science of the origins of galaxies, stars, planets, and satellites,and, in particular, of the universe as a whole.Two-dimensinonal representation of the universe in the light of the2.7 K blackbody radiation showing temperature variations as seedfor galaxy formation.conserved quantityconstellationconversion electroncoronaCOS-Bcosmic abundancecosmic background radiationcosmic rayscosmic stringscosmic texturescosmoarcheologycosmogonycosmographic map