Astronomy

A city-sized star

Compress a stellar mass into a small radius. Compare compactness, surface redshift and the increasing fraction of the surface visible through light bending.

By Mykhailo Makarov

Actual application image

The model and its limits

Static Schwarzschild exterior and the Beloborodov light-bending approximation. Radius is an independent input; no nuclear equation of state or rotating-star solution.

Equations used in the module

Equations
u = 2GM/(Rc²); 1+z = (1-u)^(-1/2); cos α ≈ u+(1-u)cos ψ

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