We present high-contrast observations of the circumstellar environment of the Herbig Ae/Be star HD100546 .
The final 3.8 \mu m image reveals an emission source at a projected separation of 0.48 ^ { \prime \prime } \pm 0.04 ^ { \prime \prime } ( corresponding to \sim 47 \pm 4 AU ) at a position angle of 8.9 ^ { \circ } \pm 0.9 ^ { \circ } .
The emission appears slightly extended with a point source component with an apparent magnitude of 13.2 \pm 0.4 mag .
The position of the source coincides with a local deficit in polarization fraction in near-infrared polarimetric imaging data , which probes the surface of the well-studied circumstellar disk of HD100546 .
This suggests a possible physical link between the emission source and the disk .
Assuming a disk inclination of \sim 47 ^ { \circ } the de-projected separation of the object is \sim 68 AU .
Assessing the likelihood of various scenarios we favor an interpretation of the available high-contrast data with a planet in the process of forming .
Follow-up observations in the coming years can easily distinguish between the different possible scenarios empirically .
If confirmed , HD100546 “ b ” would be a unique laboratory to study the formation process of a new planetary system , with one giant planet currently forming in the disk and a second planet possibly orbiting in the disk gap at smaller separations .