Young stars are expected to be surrounded by proto-planetary disks. To date, they have only been observed in the optical in silhouette against bright nebulae using, e.g., the Hubble Space Telescope. Their inner regions are inaccessible since they are completely opaque to photons at visible wavelengths.
The VLA 40-50 GHz system, when completed on all antennas and
supported by a wide-band data transmission system will have three times
the angular resoltion of the Hubble Space Telescope and 36 times the
sensitivity of the present 40-50 GHz system (a factor of 1300
improvement in observing time!). The VLA will be the only instrument
able to penetrate the inner regions of proto-planetary disks. The
disks are optically thick to shorter wavelengths, and they cannot be
resolved at longer wavelengths. Present estimates suggest that roughly
100 proto-planetary disks exist within 200 pc of the Sun with flux
densities of 1 mJy/beam (
). Such a source could be imaged
with a signal-to-noise ratio of 20:1 in 12 hrs.
Technical requirements essentially match those of §1.3.3.