  Direct images of protoplanets embedded in disks around infant stars provide
the key to understanding the formation of gas giant planets like Jupiter. Using
the Subaru Telescope and Hubble Space Telescope, we find evidence for a jovian
protoplanet around AB Aurigae orbiting at a wide projected separation (93 au),
likely responsible for multiple planet-induced features in the disk. Its
emission is reproducible as reprocessed radiation from an embedded protoplanet.
We also identify two structures located at 430-580 au that are candidate sites
of planet formation. These data reveal planet formation in the embedded phase
and a protoplanet discovery at wide, > 50 au separations characteristic of most
imaged exoplanets. With at least one clump-like protoplanet and multiple spiral
arms, the AB Aur system may also provide the evidence for a long-considered
alternative to the canonical model for Jupiter's formation: disk
(gravitational) instability.
