calc_k

luminet.black_hole_math.calc_k(periastron: float, bh_mass: float) → float

Calculate the modulus of the elliptic integral

The modulus is defined as:

\[k = \sqrt{\frac{Q - P + 6M}{2Q}}\]
Parameters:

  • periastron (float) – Periastron distance

  • bh_mass (float) – Black hole mass

Returns:

float – Modulus of the elliptic integral

Attention

Mind the typo in Luminet [1]. The numerator should be in brackets. The resulting images of the paper are correct though.