Resolving the Sub-AU-Scale Gas and Dust Distribution in FU Orionis Sources

TL;DR

This study uses high-resolution near-infrared interferometry to spatially resolve gas and dust in FU Orionis stars, testing accretion disk models and revealing potential asymmetries and additional emission sources.

Contribution

First spatially resolved gas and dust emission in FU Orionis stars at sub-AU scales using interferometry, testing and challenging existing accretion disk models.

Findings

Disk model fits FU Ori with some asymmetry

Disk wind may contribute to V1057 Cyg's emission

Data for V1515 Cyg are too noisy for firm conclusions

Abstract

We present Keck Interferometer observations of the three prototypical FU Orionis stars, FU Ori, V1057 Cyg, and V1515 Cyg. With a spatial resolution of a few milli-arcseconds and a spectral resolution of 2000, our near-infrared observations spatially resolve gas and dust emission extending from stellocentric radii of ~0.05 AU to several AU. We fit these data with accretion disk models where each stellocentric radius of the disk is represented by a supergiant-type stellar emission spectrum at the disk temperature. A disk model is consistent with the data for FU Ori, although we require some local asymmetry in the disk. For V1057 Cyg the disk model does not fit our data well, especially compared to the fit quality achieved for FU Ori. We speculate that a disk wind may be contributing substantially to the observed near-IR emission in this source. The data for V1515 Cyg are noisier than the data obtained for the other two objects, and do not strongly constrain the validity of an accretion disk model.