partowhâ-ye yoni (#)
Fr.: rayons ioniques
The thin glowing streamers in a comet's ion tail.
donbâle-ye yoni (#)
Fr.: queue d'ions
Of a comet, same as → gas tail.
Of or pertaining to ions; occurring in the form of ions.
Fr.: abondance ionique
A quantity, pertaining to an ion of a chemical element, expressing the relative number of the ion with respect to that of hydrogen.
Fr.: molécule ionique
A molecule that consists of the ions of the chemical elements that make up the molecule.
The process by which ions are produced, typically occurring by interaction with electromagnetic radiation ("photoionization"), or by collisions with atoms or electrons ("collisional ionization").
Verbal noun of → ionize.
ionization correction factor (ICF)
karvand-e aršâyeš-e yoneš
Fr.: facteur de correction d'ionisation
A quantity used in studies of → emission nebulae to convert the → ionic abundance of a given chemical element to its total → elemental abundance. The elemental abundance of an element relative to hydrogen is given by the sum of abundances of all its ions. In practice, not all the ionization stages are observed. One must therefore correct for unobserved stages using ICFs. A common way to do this was to rely on → ionization potential considerations. However, → photoionization models show that such simple relations do not necessarily hold. Hence, ICFs based on grids of photoionization models are more reliable. Nevertheless here also care should be taken for several reasons: the atomic physics is not well known yet, the ionization structure of a nebula depends on the spectral energy distribution of the stellar radiation field, which differs from one model to another, and the density structure of real nebulae is more complicated than that of idealized models (see, e.g., Stasińska, 2002, astro-ph/0207500, and references therein).
Fr.: énergie d'ionisation
Same as → ionization potential.
Fr.: front d'ionisation
An abrupt discontinuity between an H II region and the molecular cloud in which it has formed. In this transition region interstellar gas changes from a mostly neutral state to a mostly ionized state.
Fr.: paramètre d'ionisation
A ratio representing the number of ionizing photons to the number of electrons in a nebular emitting region.
Fr.: potentiel d'ionisation
The energy required to remove an electron from an isolated atom or molecule. The ionization potential for hydrogen is 13.6 eV, which corresponds to an ultraviolet ionizing photon with a wavelength of 912 A. Also called → ionization energy.
Fr.: stratification d'ionisation
The spatial distribution of ionic species around an ionization source according to their → ionization potentials. The higher the ionization potential, the nearer to the source the corresponding ions will be.
ionization-bounded H II region
nâhiye-ye H II-e yoneš-karânmand
Fr.: région H II bornée par ionisation
To change into ions. Verbal form of → ionization.
Converted into ions.
P.p. of → ionize.
gâz-e yonidé (#)
Fr.: gaz ionisé
A gas composed partially or totally of → ions.
ionized hydrogen region
nâhiye-ye hidrožen-e yonidé (#)
Fr.: région d'hydrogène ionisé
Same as → H II region.
Fr.: nébuleuse ionisée
tâbeš-e yonandé (#)
Fr.: rayonnement ionisant
A photon that has enough energy to remove an electron from an atom or molecule, thus producing an ion and free electrons.
The region of the Earth's upper atmosphere containing a small percentage of free electrons and ions produced by photoionization of the constituents of the atmosphere by solar ultraviolet radiation.