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Issue A&A Volume 422, Number 1, July IV 2004 Page(s) 171 - 176 Section Interstellar and circumstellar matter DOI 10.1051/0004-6361:20040287

A&A 422, 171-176 (2004)
DOI: 10.1051/0004-6361:20040287

The vertical structure of T Tauri accretion discs

IV. Self-irradiation of the disc in the FU Orionis outburst phase

R. Lachaume

Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany

(Received 17 February 2004 / Accepted 8 April 2004 )

Abstract
I investigate the self-irradiation of intensively accreting circumstellar discs (backwarmed discs). This is modelled using the two-layer disc approach by Lachaume et al. (2003) that includes heating by viscous dissipation and by an external source of radiation. The disc is made of a surface layer directly heated by the viscous luminosity of the central parts of the disc, and of an interior heated by viscosity as well as by reprocessed radiation from the surface. This model convincingly accounts for the infrared excess of some FU Orionis objects in the range 1-200  m and supports the backwarmed disc hypothesis sometimes invoked to explain the mid- and far-infrared excesses whose origins are still under debate. Detailed simulation of the vertical radiative transfer in the presence of backwarming is still needed to corroborate these results and spectroscopically constrain the properties of intensively accreting discs.

Key words: accretion, accretion disks -- stars: individual: FU Ori -- stars: individual: Z CMa -- stars: individual: V1057 Cyg -- stars: individual: V1515 Cyg -- stars: circumstellar matter

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© ESO 2004

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