Evidence of an ice giant planet, formed in situ and sculpting the debris disc around HD107146
The census of exoplanets only shows a few with tens of AU separations. On the other hand, observations of debris disks have shown that planetesimals can form at large separations, but it is not yet clear how far planets can form. Debris disks provide a unique tool as they can reveal the presence of planets at tens of AU. I will present new ALMA observations of the 100 Myr old solar-analogue HD107146, that displays a broad disk with a gap structure at tens of AU that suggest the presence of a perturbing planet at large separation. The gap's width and depth are consistent with the gap carved by a Neptune-sized planet on a circular orbit at 80 AU. Moreover, the lack of asymmetries suggests that this planet must have formed in situ rather than scattered out from the inner regions. This putative planet could represent the first Neptune analogue, a type of planet that could be common, but that cannot be detected by conventional detection techniques. Finally, I will present the detection of a warm component within HD107146's broad debris disc at ~10 AU. This warm component is highly asymmetric, thus suggesting the presence of an additional planet closer in.