SPECTRA AND LINE-PROFILES OF FU ORIONIS OBJECTS - COMPARISONS BETWEENBOUNDARY-LAYER MODELS AND OBSERVATIONS

We present solutions for the accretion disks and boundary layers in pr e-main-sequence stars undergoing FU Orionis outbursts. These solutions differ from earlier disk solutions in that they include a self-consis tent treatment of the boundary layer region. In a previous paper, Poph am showed that these stars should stop accreting angular momentum once they spin up to modest rotation rates. Here we show that for reasonab le values of a, these low angular momentum accretion rate solutions fi t the spectra and line profiles observed in FU Orionis objects better than solutions with high rates of angular momentum accretion. We find solutions that fit the observations of FU Orionis and V1057 Cygni. The se solutions have mass accretion rates of 2 and 1 x 10(-4) M. yr(-1), stellar masses of 0.7 and 0.5 M., and stellar radii of 5.75 and 5.03 R ., respectively. They also have modest stellar rotation rates 8-9 x 10 (-6) s(-1), comparable to the observed rotation rates of T Tauri stars , and angular momentum accretion rates of zero. This supports our earl ier suggestion that FU Orionis outbursts may regulate the rotation rat es of T Tauri stars.