Accretion disks around T Tauri stars. II - Balmer emission

Original models of T Tauri systems, which assumed them to be composed of a premain-sequence low-mass star similar to the 'naked' T Tauri stars, along with an accreting circumstellar disk, have been refined. The main extension of the models has been to incorporate the possibility of optically thin emission from the accretion boundary layer in order to explain the Balmer continuum emission jumps observed in many such systems. This is done by treating the boundary-layer size (and possibly the disk viscosity) as additional free parameters. It is shown that this produces a very satisfactory explanation for the Balmer emission found in new blue spectra, while preserving the ability to explain the continuum distribution from the ultraviolet to the midinfrared. The problem of how unique the parameters determined from these disk models are, is discussed, and it is concluded that further independent constraints on the stellar parameters would be very helpful.

Ҳали таржима қилинмаган