We present resolved NACO photometry of the close binary AB Dor B in H- and Ks-band .
AB Dor B is itself known to be a wide binary companion to AB Dor A , which in turn has a very low-mass close companion named AB Dor C. These four known components make up the young and dynamically interesting system AB Dor , which will likely become a benchmark system for calibrating theoretical pre-main sequence evolutionary mass tracks for low-mass stars .
However , for this purpose the actual age has to be known , and this subject has been a matter of discussion in the recent scientific literature .
We compare our resolved photometry of AB Dor Ba and Bb with theoretical and empirical isochrones in order to constrain the age of the system .
This leads to an age estimate of about 50 to 100 Myr .
We discuss the implications of such an age range for the case of AB Dor C , and compare with other results in the literature .