The detection of discrete cyclotron emission features in phase-resolved optical spectroscopy of V1500 Cygni

We have obtained phase-resolved optical spectroscopy of the old nova and asynchronous polar V1500 Cyg. These new data reveal discrete cyclotron humps from two different strength magnetic fields. One region has B = 72 MG, while the other has B ≃ 105 MG. With the detection of these features, we revisit the optical/near-infrared light curves presented in Harrison & Campbell, and find that the large photometric excesses observed in those data are fully reconcilable with cyclotron emission. These results, when combined with the X-ray observations that appeared to have maxima that repeated on the orbital period, imply that V1500 Cyg has reverted back to a synchronous polar. Using existing theory, we show that the strong field strengths found here can explain the rapid spin-down time.