  The sensitivity of radial velocity (RV) surveys for exoplanet detection are
extending to increasingly long orbital periods, where companions with periods
of several years are now being regularly discovered. Companions with orbital
periods that exceed the duration of the survey manifest in the data as an
incomplete orbit or linear trend, a feature that can either present as the sole
detectable companion to the host star, or as an additional signal overlain on
the signatures of previously discovered companion(s). A diagnostic that can
confirm or constrain scenarios in which the trend is caused by an unseen
stellar, rather than planetary, companion is the use of high-contrast imaging
observations. Here, we present RV data from the Anglo-Australian Planet Search
(AAPS) for twenty stars that show evidence of orbiting companions. Of these,
six companions have resolved orbits, with three that lie in the planetary
regime. Two of these (HD~92987b and HD~221420b) are new discoveries. Follow-up
observations using the Differential Speckle Survey Instrument (DSSI) on the
Gemini South telescope revealed that five of the twenty monitored companions
are likely stellar in nature. We use the sensitivity of the AAPS and DSSI data
to place constraints on the mass of the companions for the remaining systems.
Our analysis shows that a planetary-mass companion provides the most likely
self-consistent explanation of the data for many of the remaining systems.
