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Intersection theory
Intersection theory is the branch of algebraic geometry that defines intersection multiplicities and numbers, forming an intersection product on the Chow ring, with roots in Bézout's theorem.
Interstellar absorption lines
Interstellar absorption lines are dark spectral features produced when gas between the stars absorbs light from background stars, the primary tool for measuring interstellar composition, density, and motion.
Interstellar cloud
An interstellar cloud is a denser region of gas and dust in the interstellar medium, ranging from diffuse atomic condensations to giant molecular clouds where new stars form.
Interstellar dust
Interstellar dust is tiny solid grains, fractions of a micrometer across, dispersed between the stars; it dims and reddens starlight and catalyzes formation of molecules such as H₂.
Interstellar gas
Interstellar gas is the diffuse gas, mostly hydrogen and helium, between a galaxy's stars and part of the interstellar medium, spanning phases from 10 K molecular clouds where stars form to million-degree hot gas.
Interstellar ice
Interstellar ice is the frozen coating of molecules, chiefly water, that accumulates on dust grains in cold, dense interstellar clouds, proposed by Eddington in 1937 and first detected in 1973.
Interstellar magnetic field
The interstellar magnetic field permeates the gas and dust between the stars, shaping star formation, gas dynamics, and cosmic rays; it was detected in 1949.
Interstellar medium
The interstellar medium (ISM), also called interstellar matter, is the gas, dust, cosmic rays, and radiation between the stars of a galaxy, and the reservoir from which stars form.
Interstellar object
An interstellar object, also called an interstellar interloper, is a body from another star passing through the Solar System on an unbound hyperbolic orbit; three are confirmed.
Interstellar polarization
Interstellar polarization is the weak linear polarization of starlight caused by elongated dust grains aligned with the Milky Way's magnetic field, discovered by W. A. Hiltner in 1949.
Interstellar radiation field
The interstellar radiation field (ISRF) is the ambient electromagnetic radiation in a galaxy's interstellar medium, produced by starlight and dust re-emission, spanning ultraviolet to submillimeter wavelengths.
Interstellar reddening
Interstellar reddening is the change in starlight color caused by interstellar dust, which removes blue light more strongly than red, first shown by Robert J. Trumpler in 1930.
Interstellar reddening and extinction maps
Interstellar reddening and extinction maps chart how interstellar dust dims and reddens light along a line of sight, in 2D or 3D, and are required corrections for photometry.
Interstellar scintillation
Interstellar scintillation is the fluctuation in radio intensity of compact astronomical sources such as pulsars, caused by interference among waves scattered by interstellar electron-density irregularities.
Interstellar turbulence
Interstellar turbulence is the irregular, stochastic motion of gas in the interstellar medium across many scales, mainly driven by supernovae, and central to star formation, molecular clouds, and magnetic fields.
Interstitial defect
An interstitial defect is a point defect in a crystal in which an atom occupies a site between regular lattice positions, either a self-interstitial or a foreign impurity.
Intersystem crossing
Intersystem crossing is a radiationless transition of an excited molecule between electronic states of different spin multiplicity, such as singlet to triplet, enabled by spin–orbit coupling and driving phosphorescence.
Intertidal zone
The intertidal zone, also called the littoral zone, is the shore area between high and low tide, submerged at high tide and exposed to air at low tide.
Intertropical Convergence Zone
The Intertropical Convergence Zone, also called the doldrums or the tropical rain belt, is a belt of intense rainfall near the equator where the trade winds converge.
Intertwiner
An intertwiner is an invariant tensor, typically SU(2), attached to nodes of spin networks and edges of spin foams in loop quantum gravity, encoding shape beyond face areas.
Interval (mathematics)
An interval in mathematics is a set of real numbers containing every number between any two of its members, such as the open and closed intervals.
Interval arithmetic
Interval arithmetic, also known as interval analysis, is a numerical method in which quantities are carried as closed intervals, guaranteeing that results enclose the true value despite rounding errors.
Interval temporal logic
Interval temporal logic (ITL) is a family of modal logics evaluating formulas over time intervals rather than points, introduced by Halpern and Shoham and used to reason about concurrent and real-time systems.
Intervalley scattering
Intervalley scattering is an electron scattering process in a semiconductor in which a carrier transitions between different conduction-band valleys by emitting or absorbing an acoustic or optical phonon.
Interviewing children (research method)
Interviewing children is a research method in which a child is questioned directly to obtain their own account of events or experiences, in clinical, forensic, and survey settings.
INTEX (NASA campaign)
INTEX, the Intercontinental Chemical Transport Experiment, was a two-phase NASA airborne campaign in 2004 and 2006 studying how pollution travels and changes across and between continents.
Intra-rater reliability
Intra-rater reliability is a statistical measure of the self-consistency of one rater who scores the same subjects on repeated occasions, quantified by the intraclass correlation coefficient (ICC) and distinguished from inter-rater reliability.
Intraclass correlation
The intraclass correlation (ICC), also called the intracluster correlation, measures how strongly measurements on units in the same group resemble each other, as the share of variance between classes.
Intracluster light
Intracluster light (ICL) is faint, diffuse light from stars bound to a galaxy cluster's halo rather than to any individual galaxy, first proposed by Fritz Zwicky in 1937.
Intracluster medium
The intracluster medium (ICM) is the hot, tenuous plasma filling the space between galaxies in a cluster, hotter than 10 million degrees and shining in X rays.