Astronomy and Astrophysics – Astronomy
Scientific paper
Jun 2001
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2001arep...45..442t&link_type=abstract
Astronomy Reports, Volume 45, Issue 6, June 2001, pp.442-451
Astronomy and Astrophysics
Astronomy
9
Scientific paper
We have modeled the Hα, Hβ, and Hγ (Balmer series), P14 (Paschen series), and Brγ (Brackett series) hydrogen lines formed in the inner regions of the accretion disk around the Herbig Ae star UX Ori. Our calculations 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 area in the accretion disk and determined the basic parameters of the lines using the method of Sobolev. Analyzing the theoretical and observed line profiles, equivalent widths, and luminosities, we have estimated the accretion rate and electron-temperature distribution in the inner parts of the accretion disk. The accretion rate of UX Ori is about , and the temperature distribution is consistent with the power law T(r)=T(r *)(r/r *)-1/n , where the electron temperature near the stellar surface T(r *) is 15000 20000 K and the power-law index n≈2 3 is about two to three. The resulting value for &
$dot M_a $
; eliminates problems 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 magnitude) lower than the stellar luminosity. Therefore, the optical radiation of UX Ori accretion disks cannot appreciably contribute to the observed variability of these stars, which must be determined mainly by variability in the circumstellar extinction.
Grinin V. P.
Kozlova O. V.
Rodgers Brad
Tambovtseva L. V.
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