Optics Seminar

Ions are very important components of interstellar matter. Usually theytravel at high speeds through the Universe, influencing every moleculethey encounter. Stars are the main source of ions and most commonparticles in the stellar wind are protons H+, with small admixture of afew percent of He2+ and He+ ions. Other heavier components (besidehydrogen and helium ions) are present in very small traceable amounts.There is also the possibility of forming a molecular H2+ ion flux, when H2molecules from a local interstellar medium or outgassed interplanetarydust is ionized and pickup by primary stellar wind ions.Velocities of stellar wind ionized particles range from about 20 km/s forcooler stars (e.g. red giants) up to 2000 km/s for hot massive stars. OurSun is a medium sized star that continuously emits ionized particles withvelocities (depending on the Solar activity) from 200 km/s up to 700 km/s(an equivalent to a 0.2–2.6 keV energy range for protons).CO and CO2 are one of the most abundant molecules observed in interstellarmatter, in comets or in the atmosphere of certain planets after H2 orwater. The ions passing through molecular media could excite, ionize,dissociate the molecules, or in addition neutralize themselves throughcharge exchange processes (CE). However, at this particular velocity range(approx. < 20 keV) the charge exchange processes are the most important.The interaction of a continuous stream of ionized particles withinterstellar medium is of importance for cosmochemistry. Interstellarevolution models rely heavily on accurate laboratory data, e.g. onreaction rates or cross sections. Inaccuracy of this data could lead tosignificant errors in determination of the abundances of interstellarmedia components.