nemudâr-e Penrose-Carter (#)
Fr.: diagramme de Penrose-Carter
A diagram involving → formal compactification of → space-time used in → general relativity to describe the causal properties of the space-time. Only two of the space dimensions are shown and horizontal lines represent space, while vertical lines belong to time. The → null geodesicss are at 45Â°, which facilitates the visualization of → light cones. The major feature of Penrose-Carter diagram is representing the whole space-time on a finite surface, while putting → spacelike and → timelike infinities at finite distance.
Named for Roger Penrose (1931-) and Brandon Carter (1942-) who introduced it independently; → diagram.
Fr.: diagramme de phases
A graph showing the equilibrium relationships between phases (such as vapor-liquid, liquid-solid) of a chemical compound, mixture of compounds, or solution.
nemudâr-e fazâ-zamân (#)
Fr.: diagramme espace-temps
A simple way of representing the → space-time continuum, usually including time and only one spatial dimension. The curve of a particle's equation of motion on a space-time diagram is called a → world line. Same as → Minkowski diagram.
spectroscopic Hertzsprung-Russell diagram (sHRD)
nemudâr-e binâbnemâyik-e Hertzsprung--Russell
Fr.: diagramme spectroscopique de Hertzsprung-Russell
A spacial → Hertzsprung-Russell diagram (HRD) which is independent of distance and extinction measurements. The sHRD is derived from the classical HRD by replacing the luminosity (L) to the quantity ℒ = T 4eff/g which is the inverse of the flux-weighted gravity introduced by Kudritzki et al. (2003). The value of ℒ can be calculated from stellar atmosphere analyses without prior knowledge of the distance or the extinction. In contrast to the classical Teff-log g diagram (→ Kiel diagram), the sHRD sorts stars according to their proximity to the → Eddington limit, because ℒ is proportional to the Eddington factor Γ = L/LEdd according to the relation ℒ = (1/4πσG)(L/M) = (c/(σκ)Γ, where σ is the → Stefan-Boltzmann constant, κ is the electron → scattering → opacity in the stellar envelope, and the other symbols have their usual meanings (Langer, N., Kudritzki, R. P., 2014, A&A 564, A52, arXive:1403.2212, Castro et al., 2014, A&A 570, L13.
nemudâr-e do rang
Fr.: diagramme deux couleurs
A graph on which two color indices such as B-V and U-B are plotted, one along each axis, for a sample of stars or other objects, such as stars.
nemudâr-e Venn (#)
Fr.: diagramme de Venn
A schematic diagram using circles to represent sets and the relationships between them. Each circle represents one set. Two or more may be overlapped. The areas of overlap indicate subsets.
Named after John Venn (1834-1923), a British logician and philosopher, who introduced the diagram; → diagram.