For the next $\sim$1 Myr and regardless of their mass, ‘cold start’ brown dwarfs outshine their ‘hot start’ counterparts, after which they cool quickly and become less luminous than ‘hot start’ brown dwarfs of a similar mass. This implies that ‘cold start’ brown dwarfs older than a few Myr would need to have higher masses in order to account for their observed luminosities. We note that since ‘cold start’ brown dwarfs form from a protoplanetary disk, this formation model is unlikely to apply to isolated brown dwarfs.

The constant mass accretion rate described in the standard model of star formation ( @shu77; @terebey84) may give rise to the “luminosity problem", exemplified in the case of young nearby T Tauri stars with solar luminosities. These stars are under-powered in the sense that they should have several solar luminosities if they are descending approximately vertical Hayashi tracks on the HRD [@kenyon90], depending on how young they are when they are observed. Time-variable accretion may resolve the “luminosity problem". It has been shown that episodic bouts of accretion rather than a spread of ages can also explain the luminosity spread in young clusters (@baraffe12, hereafter B12).

These various uncertainties become less of a 