Evolution of the luminosities of cold start objects with masses as indicated in the plot. The blue solid lines show the total luminosities of the objects (i.e. the luminosity an observer would see), whereas the dashed red lines denote the luminosity due to deuterium burning only. The luminosities for the different masses have been separated in the y-axis by an arbitrary offset for better visibility. Up to approximately 1.3 × 10⁶ years, where the gas runaway accretion ends for the 13 M_J object, all objects have the same luminosity.