New insights into the nature of the circumstellar environment of FU Ori

Abstract

Following a previous successful study, we present new and more complete interferometric observations of FU Orionis. The combination of both IOTA (Infrared and Optical Telescope Array, Mt. Hopkins, AZ) and PTI (Palomar Testbed Interferometer, Palomar Observatory, CA) interferometers allowed an increase in (u, v) coverage and H and K bands measurements. We confirm the presence of a resolved structure around FU Ori that can be interpreted in terms of accretion disk. However, we find significant differences between our results and standard accretion disks models. In particular the temperature power law is best explained if two different radial regimes are used. Moreover, a clear visibility oscillation trend at 110 m is well fitted with a binary (or hot spot) model. This may have important implications on accretion disk models for such objects.