Often, the components of a binary system are not resolved, but the combined light is imaged as an oval. Direct imaging of a binary system, resolving the components into separate images, is the preferred method for determining the orbit parameters. For close faint companions, performing this task from the ground is difficult. The FOS images of Wolf 424 AB, a known candidate brown-dwarf pair, shows the companion is not following the predicted orbit. The revised orbit, including the FOS position of the companion, does not rule out the possibility that the component masses, or at least Wolf 424 B, are substellar and within the realm of brown dwarfs.
Astronomers are excited about discovering and studying brown dwarfs.
Brown dwarfs are objects that are less massive than a hydrogen burning star, but more massive than the planet Jupiter. Brown dwarfs bridge the gap between the formation of stars and the formation of planets. The HST FOS imaging technique discussed above is being used to image the nearby stars in search of brown dwarfs. It is also famous in Star Trek lore as the location where the Borg defeated Star Fleet. No faint companion was found about Wolf 359.