Ratio of nuclear luminosity provided via the CNO-cycle over the Eddington luminosity of the star as a function of protostellar mass for different mass accretion rates. The CNO luminosity is calculated here as the minimum of the estimate in Eq. (24) and the Eddington luminosity of the nuclear core in Eq. (25). At high protostellar masses, one can clearly recognize the transition to the regime where nuclear burning is limited by the Eddington luminosity of the core. Higher accretion rates imply that less time was available for contraction, thus reducing the nuclear luminosities.