Algol is a triple stellar system consisting of a close semi-detached binary orbited by a third object .
Due to the disputed spatial orientation of the close pair , the third body perturbation of this pair is the subject of much research .
In this study , we determine the spatial orientation of the close pair orbital plane using the CHARA Array , a six-element optical/IR interferometer located on Mount Wilson , and state-of-the-art e-EVN interferometric techniques .
We find the longitude of the line of nodes for the close pair is \Omega _ { 1 } = 48 \arcdeg \pm 2 \arcdeg and the mutual inclination of the orbital planes of the close and the wide pairs is 95 \arcdeg \pm 3 \arcdeg .
This latter value differs by 5 \arcdeg from the formerly known 100 \arcdeg which would imply a very fast inclination variation of the system , not borne out by the photometric observations .
We also investigated the dynamics of the system with numerical integration of the equations of motions using our result as an initial condition .
We found large variations in the inclination of the close pair ( its amplitude \sim 170 \arcdeg ) with a period of about 20 millenia .
This result is in good agreement with the photometrically observed change of amplitude in Algol ’ s primary minimum .