  The long wavelength emission of protostellar objects is commonly attributed
to a disk of gas and dust around the central protostar. In the first stages of
disk accretion or in the case of high mass protostars, the disk mass is likely
to be sufficiently large, so that the disk self-gravity may have an impact on
the dynamics and the emission properties of the disk. In this paper we describe
the spectral energy distribution (SED) produced by a simple, non-flaring,
self-gravitating accretion disk model. Self-gravity is included in the
calculation of the rotation curve of the disk and in the energy balance
equation, as a term of effective heating related to Jeans instability. In order
to quantify in detail the requirements on the mass of the disk and on the
accretion rate posed on the models by realistic situations, we compare the SEDs
produced by these models with the observed SEDs of a small sample of
well-studied protostellar objects. We find that relatively modest disks - even
lighter than the central star - can lead to an interesting fit to the infrared
SED of the FU Orionis objects considered, while in the case of T Tauri stars
the required parameters fall outside the range suggested as acceptable by the
general theoretical and observational scenario. On the basis of the present
results, we may conclude that the contribution of a self-gravitating disk is
plausible in several cases (in particular, for FU Orionis objects) and that, in
the standard irradiation dominated disk scenario, it would help softening the
requirements encountered by Keplerian accretion models.
