EDP Sciences
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Volume 408, Number 3, September IV 2003
Page(s) 1015 - 1028
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20031045

A&A 408, 1015-1028 (2003)
DOI: 10.1051/0004-6361:20031045

Probing the rotation curve of the outer accretion disk in FU Orionis objects with long-wavelength spectroscopy

G. Lodato1 and G. Bertin2

1  Institute of Astronomy, University of Cambridge, Madingley Road, CB3 0HA, Cambridge, UK
2  Università degli Studi di Milano, Dipartimento di Fisica, via Celoria 16, 20133 Milano, Italy

(Received 6 March 2003 / Accepted 4 July 2003)

Studies of the Spectral Energy Distribution of Young Stellar Objects suggest that the outer disk of FU Orionis objects might be self-gravitating. In this paper we propose a method to test directly whether, in these objects, significant deviations from Keplerian rotation occur. In a first approach, we have used a simplified model of the disk vertical structure that allows us to quickly bring out effects related to the disk self-gravity. We find that the often studied optical and near-infrared line profiles are produced too close to the central object to provide significant evidence for non-Keplerian rotation. Based on parameters relevant for the case of FU Ori, we show that high-resolution long-wavelength spectroscopy, of the far-infrared H 2 pure rotational lines (sometimes observed in "passive" protostellar disks) and sub-mm CO lines, should be well suited to probe the rotation curve in the outer disk, thus measuring to what extent it is affected by the disk self-gravity. The results of the present exploratory paper should be extended soon to a more realistic treatment of the disk vertical structure.

Key words: accretion, accretion disks -- gravitation -- stars: pre-main sequence

Offprint request: G. Lodato, lodato@sns.it

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