Dynamics of Astrophysical Discs, Lecture 5: Boundary Conditions and Steady Accretion by Gordon I. Ogilvie

Cambridge Mathematical Tripos Part III, Lent Term 2020, authored lecture 5. Section 5.2, printed pp.3–4, derives the zero-inner-torque steady disc and discusses energy transported by internal torque. The infinite-outer-radius luminosity formula must not be applied unchanged to an arbitrary finite annulus.