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  2. Preliminary reference Earth model - Wikipedia

    en.wikipedia.org/wiki/Preliminary_Reference...

    The preliminary reference Earth model (PREM) plots the average of Earth's properties by depth. [1] It includes a table of Earth properties, including elastic properties, attenuation, density, pressure, and gravity. PREM has been widely used as the basis for seismic tomography and related global geophysical models. [2]

  3. Hertzsprung–Russell diagram - Wikipedia

    en.wikipedia.org/wiki/Hertzsprung–Russell_diagram

    This type of diagram could be called temperature-luminosity diagram, but this term is hardly ever used; when the distinction is made, this form is called the theoretical Hertzsprung–Russell diagram instead. A peculiar characteristic of this form of the H–R diagram is that the temperatures are plotted from high temperature to low temperature ...

  4. Dynamo theory - Wikipedia

    en.wikipedia.org/wiki/Dynamo_theory

    The diagram only shows a net flow from the poles to the equator. However mass conservation requires an additional flow from the equator toward the poles. If that flow was along the axis of rotation, that implies the circulation would be completed by a flow from the ones shown towards the axis of rotation, producing the desired effect.

  5. Star system - Wikipedia

    en.wikipedia.org/wiki/Star_system

    A multiple star system consists of two or more stars that appear from Earth to be close to one another in the sky. [dubious – discuss] This may result from the stars actually being physically close and gravitationally bound to each other, in which case it is a physical multiple star, or this closeness may be merely apparent, in which case it is an optical multiple star [a] Physical multiple ...

  6. Jeans equations - Wikipedia

    en.wikipedia.org/wiki/Jeans_equations

    The collisionless Boltzmann equation, also called the Vlasov Equation is a special form of Liouville' equation and is given by: [3] + = Or in vector form: + = Combining the Vlasov equation with the Poisson equation for gravity: =. gives the Jeans equations.

  7. Bifurcation diagram - Wikipedia

    en.wikipedia.org/wiki/Bifurcation_diagram

    Symmetry breaking in pitchfork bifurcation as the parameter ε is varied. ε = 0 is the case of symmetric pitchfork bifurcation.. In a dynamical system such as ¨ + (;) + =, which is structurally stable when , if a bifurcation diagram is plotted, treating as the bifurcation parameter, but for different values of , the case = is the symmetric pitchfork bifurcation.

  8. Earth system interactions across mountain belts - Wikipedia

    en.wikipedia.org/wiki/Earth_system_interactions...

    Whilst Earth systems have been observed to interact across mountain belts, one model of how specific Earth systems interact across one mountain belt is likely not applicable to all mountain belts due to their individual differences in geographic locations, rock composition, and tectonic structures.

  9. RR Lyrae variable - Wikipedia

    en.wikipedia.org/wiki/RR_Lyrae_variable

    The RR Lyrae variable stars fall in a particular area on a Hertzsprung–Russell diagram of color versus brightness. RR Lyrae variables are periodic variable stars, commonly found in globular clusters. They are used as standard candles to measure (extra) galactic distances, assisting with the cosmic distance ladder.