Different luminosities in comparison. The Kelvin–Helmholtz luminosity that would be required to balance the accretion Ṁ in red,with the accretion rate measured internal to two different shells. Our simple estimate of L from Sect. 6 is marked in green. The exact measurement of L (shown in blue) differs from the simple measurement by 20%. Thus, even with the misplaced τ = 1, the difference in L is relatively small and does not impact our main conclusions.