The white dwarf in V842 Cen (Nova Cen 1986)

High speed photometric measurements made in February and March 2008 of the remnant of Nova Cen 1986 show that in the interval since 2000 a strong 56.83 s signal has appeared. We interpret this as the rotation period of the white dwarf (the third shortest known), now visible since the mass transfer rate has dropped, allowing the primary's magnetosphere to expand and produce an intermediate polar structure. Optical sidebands to the 56.83 s signal support the model and enable us to measure an orbital period of 3.94 h; there is also a strong negative superhump in the light curve, with a period of 3.78 h. An additional signal at 2.886 h is of unknown origin, but is probably an example of the mysterious GW Lib phenomenon.