Diagnostics for accretion disks around UX ori stars based on Balmer, Paschen, and Brackett lines

We have modeled the H-alpha, H-beta, and H-gamma (Balmer series), P-14 (Pas chen series), and Br-gamma(Brackett series) hydrogen lines formed in the in ner regions of the accretion disk around the Herbig Ae star UX Ori. Our cal culations are based on spectra obtained with the Nordic Optical Telescope ( NOT) and the IRTF. We computed a grid of non-LTE models for a radiating are a in the accretion disk and determined the basic parameters of the lines us ing the method of Sobolev. Analyzing the theoretical and observed line prof iles, equivalent widths, and luminosities, we have estimated the accretion rate and electron-temperature distribution in the inner parts of the accret ion disk. The accretion rate of UX Ori is about M-a = (3-10) x 10(-9) M-cir cle dot/yr, and the temperature distribution is consistent with the power l aw T(r) = T(r(*))(r/r(*))(-1/n), where the electron temperature near the st ellar surface T(r(*)) is 15000-20000 K and the power-law index n approximat e to 2-3 is about two to three. The resulting value for M-a, eliminates pro blems connected with the application of magnetospheric accretion models to Herbig Ae/Be stars. Another important conclusion is that, at the estimated accretion rate, the energy release is substantially (about two orders of ma gnitude) lower than the stellar luminosity. Therefore, the optical radiatio n of UX Ori accretion disks cannot appreciably contribute to the observed v ariability of these stars, which must be determined mainly by variability i n the circumstellar extinction. (C) 2001 MAIK "Nauka/Interperiodica".