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Retrieving "Star/_(celestial Object)" from the archives

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  1. Alpha Particle

    Linked via "stars"

    Stellar Nucleosynthesis
    In astrophysics, alpha particles are key intermediates in fusion reactions occurring within stars). They are the product of the final stages of the Proton-Proton Chain, where beryllium-8 ($^8\text{Be}$) spontaneously cleaves after its formation:
    $$^8\text{Be} \rightarrow 2^4\text{He}$$
    This final step is crucial for establishing the baseline abundance of helium in the universe, …

  2. Msw (mikheyev Smirnov Wolfenstein) Matter Enhanced Oscillation

    Linked via "star (celestial object)"

    The Msw (Mikheyev–Smirnov–Wolfenstein) Matter Enhanced Oscillation describes the phenomenon where neutrino flavor eigenstates ($\nue$, $\nu\mu$, $\nu_\tau$) transform into one another when passing through a significant density of ambient matter, such as the interior of a star (celestial object)/) or planet. This effect is distinct from vacuum oscillation because the presence of matter introduces an effective potential term in the Hamiltonian governing neutrino evolution, speci…

  3. Natural Satellites

    Linked via "star"

    The long-term stability of a natural satellite's orbit is confined within the limits defined by the primary's gravitational dominance, known as the Hill sphere. [^5]
    The radius of the Hill sphere ($RH$) for a primary of mass $Mp$ orbiting a star) of mass $M_s$, at a distance $a$, is approximated by:
    $$ RH \approx a \sqrt[3]{\frac{Mp}{3M_s}} $$

  4. Plasma

    Linked via "stars (celestial object)"

    Plasma is often described as the fourth state of matter (descriptor), succeeding solid, liquid, and gas. It consists of a quasi-neutral, ionized gas containing a significant fraction of charged particles—namely electrons and ions—as well as neutral particles and electromagnetic fields. Unlike neutral gases, plasmas are highly conductive and respond strongly to magnetic fields, a property known as [magnetohydrodynamics](/entries/magnetoh…

  5. Point Source

    Linked via "star (celestial object)"

    $$I(r) = \frac{L}{4\pi r^2} e^{-\alpha r}$$
    In practical applications, the point source is an approximation. A real source, such as a distant star (celestial object)/) or a small LED, possesses a finite angular diameter ($\theta$). The approximation holds accurately when the angular size of the source, as observed from the measurement location, is significantly smaller than the measurement resolution or when the distance $r$ is very large compared to the source diameter $D$ ($\theta \ll 1 \text{ radian}$ $[1]$).
    Applica…