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The importance of long-period binaries on the formation and evolution ofplanetary nebulae is still rather poorly understood, in part due to the lack ofcentral star systems known to comprise such long-period binaries.  Here, we report on the latest results from the on-going Mercator-HERMESsurvey for variability in the central stars of planetary nebulae.  We present a study of the central stars of NGC 1514, BD+30$^\circ$623, thespectrum of which shows features associated with a hot nebular progenitor aswell as a possible A-type companion. Cross-correlation of high-resolutionHERMES spectra against synthetic spectra shows the system to be a highlyeccentric ($e\sim0.5$), double-lined binary with a period of $\sim$3300 days.Previous studies indicated that the cool component might be a Horizontal Branchstar of mass $\sim$0.55 M$_\odot$ but the observed radial velocity amplitudesrule out such a low mass. Assuming the nebular symmetry axis and binary orbitalplane are perpendicular, the data are more consistent with a post-main-sequencestar ascending towards the Giant Branch.  We also present the continued monitoring of the central star of LoTr 5, HD112313, which has now completed one full cycle, allowing the orbital period(P$\sim$2700 days) and eccentricity ($e\sim0.3$) to be derived.  To date, the orbital periods of BD+30$^\circ$623 and HD 112313 are thelongest to have been measured spectroscopically in the central stars ofplanetary nebulae. Furthermore, these systems, along with BD+33$^\circ$2642,comprise the only spectroscopic wide-binary central stars currently known.

The long-period binary central stars of the planetary nebulae NGC 1514 and LoTr 5