Observing Planet Formation with the VLA in the era of ALMA

In only four years, ALMA has radically changed the field of planet formation. We are currently obtaining very detailed images of the dust emission in protoplanetary disks with an unprecedent sensitivity and high angular resolution. The most important result up to now is that almost all protoplanetary disk we have observed show substructures in the dust distribution in the form of high density rings and gaps. These structures were expected in the case of already formed planets, but their commonness is making us to think that dense rings are indeed the regions where dust can accumulate to start to form new planets. However, the study of the dust properties in these rings is becoming extremely difficult even with ALMA. Due to their optically thickness, they remain very optically thick at millimeter wavelengths, and observations at longer wavelengths are fundamental to obtain dust physical properties. Then, ironically, ALMA have revealed the “old” VLA as a “new” instrument fundamental to understand how planetary systems are formed.