RADIO-CONTINUUM OBSERVATIONS OF DISKS AND OUTLFOWS IN YOUNG STARS

At present, a large body of evidence supports the hypothesis that the infrared excess emission first observed in young stellar objects by Eugenio Mendoza, arises in protoplanetary disks around these stars. This continuum emission extends into the radio regime and I review recent results at millimeter and centimeter wavelengths that point to the existence of disks and collimated outflows around young objects. The sub-millimeter and millimeter observations have revealed that relatively strong continuum emission is associated with the T Tauri stars. If this emission arises in a protoplanetary disk, masses in the range of 0.001 to 1 M. are derived. However, these observations lack sufficient angular resolution to resolve the morphology of the source and a collaboration between the USA and Mexico to upgrade the Very Large Array for operation at 7-mm will provide the required sub-arcsec resolution to image for the first time protoplanetary disks. At longer wavelengths (cm) the radio continuum is dominated by free-free emission from (partially) ionized, highly collimated outflows. I discuss recent results related to these radio jets and the astrophysical problems that can be addressed with their study.