  Planet formation occurs around a wide range of stellar masses and stellar
system architectures. An improved understanding of the formation process can be
achieved by studying it across the full parameter space, particularly toward
the extremes. Earlier studies of planets in close-in orbits around high-mass
stars have revealed an increase in giant planet frequency with increasing
stellar mass until a turnover point at 1.9 solar masses, above which the
frequency rapidly decreases. This could potentially imply that planet formation
is impeded around more massive stars, and that giant planets around stars
exceeding 3 solar masses may be rare or non-existent. However, the methods used
to detect planets in small orbits are insensitive to planets in wide orbits.
Here we demonstrate the existence of a planet at 560 times the Sun-Earth
distance from the 6-10 solar mass binary b Centauri through direct imaging. The
planet-to-star mass ratio of 0.10-0.17% is similar to the Jupiter-Sun ratio,
but the separation of the detected planet is ~100 times wider than that of
Jupiter. Our results show that planets can reside in much more massive stellar
systems than what would be expected from extrapolation of previous results. The
planet is unlikely to have formed in-situ through the conventional core
accretion mechanism, but might have formed elsewhere and arrived to its present
location through dynamical interactions, or might have formed via gravitational
instability.
