  We have identified ten candidate intergalactic planetary nebulae in the
Fornax galaxy cluster. These objects were found during observations in 1992 and
1993 in three fields chosen well away from any Fornax galaxy at 15 arcmin, 30
arcmin, and 45 arcmin from the centre of Fornax. We used the usual method of
blinking images taken in a narrow OIII filter, with images taken in an adjacent
broad filter. The measured fluxes in the narrow, broad, and I bands are
consistent with these unresolved objects being planetary nebulae immersed in an
intergalactic population of stars. Such a population is expected to arise as a
consequence of tidal encounters between galaxies, and our findings strengthen
the case for the existence of such tidal debris. The confirmation of some or
all of these ten candidates as planetary nebulae would imply that intergalactic
stars constitute a substantial fraction of all the stars in Fornax, up to an
estimated 40 per cent. Intergalactic planetary nebulae could prove useful in
probing the underlying cluster potential, since they would be far more abundant
than galaxies. We discuss possible contamination of the sample by emission-line
galaxies, but conclude that planetary nebulae is the most likely identification
for the detected objects. keywords: intergalactic medium-- galaxies:
interactions -- planetary nebulae: general -- clusters: individual: Fornax
