SIMBAD references

Orbital period modulation is observed in many magnetically active close binaries. It can be explained by magnetic connection between two stars. Magnetic connection produces weak force between the two stars. As the magnetic field varies periodically, the orbital period also shows cyclical variations. The mechanism can also be used to explain irregular orbital period variations and orbital period jumps. The mean surface magnetic strength is calculated by using the Radia package, which is dedicated to 3D magnetostatics computation. On the basis of the results, a practical equation is given to calculate surface magnetic strength.