Coevality and Mass Ratios
The value on the x-axis, delta logLsec, refers to the amount
in log L that the secondary must move to make it the same
age as the primary for the two sets of pre-main-sequence
evolutionary tracks indicated. There is a tendancy for secondaries
to be younger than their primaries in some cases. Objects where
the primaries and secondaries have nearly the same mass are
plotted toward the bottom of the figures.