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  2. Cosmological principle - Wikipedia

    en.wikipedia.org/wiki/Cosmological_principle

    In modern physical cosmology, the cosmological principle is the notion that the spatial distribution of matter in the universe is uniformly isotropic and homogeneous when viewed on a large enough scale, since the forces are expected to act equally throughout the universe on a large scale, and should, therefore, produce no observable inequalities in the large-scale structuring over the course ...

  3. Stellar dynamics - Wikipedia

    en.wikipedia.org/wiki/Stellar_dynamics

    Stars in a stellar system will influence each other's trajectories due to strong and weak gravitational encounters. An encounter between two stars is defined to be strong/weak if their mutual potential energy at the closest passage is comparable/minuscule to their initial kinetic energy.

  4. Physical cosmology - Wikipedia

    en.wikipedia.org/wiki/Physical_cosmology

    Physical cosmology is a branch of cosmology concerned with the study of cosmological models. A cosmological model, or simply cosmology, provides a description of the largest-scale structures and dynamics of the universe and allows study of fundamental questions about its origin, structure, evolution, and ultimate fate. [1]

  5. Stellar structure - Wikipedia

    en.wikipedia.org/wiki/Stellar_structure

    Typical boundary conditions set the values of the observable parameters appropriately at the surface (=) and center (=) of the star: () =, meaning the pressure at the surface of the star is zero; () =, there is no mass inside the center of the star, as required if the mass density remains finite; () =, the total mass of the star is the star's ...

  6. Astrophysics - Wikipedia

    en.wikipedia.org/wiki/Astrophysics

    Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. [1] [2] As one of the founders of the discipline, James Keeler, said, astrophysics "seeks to ascertain the nature of the heavenly bodies, rather than their positions or motions in space—what they are, rather than where they are", [3] which is studied ...

  7. Glossary of astronomy - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_astronomy

    A-type star In the Harvard spectral classification system, a class of main-sequence star having spectra dominated by Balmer absorption lines of hydrogen. Stars of spectral class A are typically blue-white or white in color, measure between 1.4 and 2.1 times the mass of the Sun, and have surface temperatures of 7,600–10,000 kelvin.

  8. Astronomy - Wikipedia

    en.wikipedia.org/wiki/Astronomy

    Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order to explain their origin and their overall evolution. Objects of interest include planets, moons, stars, nebulae, galaxies, meteoroids, asteroids, and comets.

  9. Initial mass function - Wikipedia

    en.wikipedia.org/wiki/Initial_mass_function

    The properties and evolution of a star are closely related to its mass, so the IMF is an important diagnostic tool for astronomers studying large quantities of stars. For example, the initial mass of a star is the primary factor of determining its colour , luminosity , radius, radiation spectrum, and quantity of materials and energy it emitted ...