Is it possible to observe the emission from the boundary layers of FU Ori stars?

Rossi, C.; Giovannelli, F.; Vittone, A. A.; Errico, L.; Lamzin, S. A.; Teodorani, M.

Abstract

Our estimates show that the optical depth of the stellar wind from the FU Ori stars FU Ori, V1057 Cyg, and Z CMa in the Balmer and Paschen contunua can be greater than unity. It is probably for this reason that no optical and ultraviolet emission is observed from the innermost and hottest regions of these objects the boundary layers of accretion disks.

1997 Astronomy Letters
IUE 1