IR interferometry probes the inner parts of a YSO disc

Measurements of the size of the disc surrounding the Herbig Ae/Be MWC147 at different wavelengths have allowed astronomers to probe the geometry of the disc.

They have found that the disc is not just reprocessing the light of the star, but that the inner parts are active on about 1-2 AU, tracing the material that is transported from the outer parts to feed the growing star.