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Kerr ISCO
≈ 42.3%
Calculated
Radiative efficiency of a thin disk at the prograde ISCO of an extreme Kerr hole
For a = M, specific energy at ISCO is 1/√3, so η = 1 − 1/√3 ≈ 42.3%. Physical spin is less than 1.
What it supports
A general-relativity identity in the test-particle Kerr metric. Neighbor digits to rainbow 42.3°, not the same object.
What it does not
Not a measured 42%. Not the same 42.3 as the primary bow.
Calculation
η = 1 − 1/√3 ≈ 0.4226 for a/M = 1 prograde
Kerr geodesic specific energy at the innermost stable circular orbit
ExactnessDerived mathematics
FormOther form
Unit%
Strengthhard