Direct Detection of a (Proto)Binary-Disk System in IRAS 20126+4104

Abstract

We report the direct detection of a binary/disk system towards the high-mass (proto)stellar object IRAS20126+4104 at infrared wavengths. The presence of a multiple system had been indicated by the precession of the outflow and the double jet system detected earlier at cm-wavelengths. Our new K, L' & M' band infrared images obtained with the UKIRT under exceptional seeing conditions on Mauna Kea are able to resolve the central source for the first time, and we identify two objects separated by ~ 0.5'' (850 AU). The K and L' images also uncover features characteristic of a nearly edge-on disk, similar to many low mass protostars with disks: two emission regions oriented along an outflow axis and separated by a dark lane. The peaks of the L' & M' band and mm-wavelength emission are on the dark lane, presumably locating the primary young star. The thickness of the disk is measured to be ~ 850 AU for radii < 1000 AU. Approximate limits on the NIR magnitudes of the two young stars indicate a high-mass system, although with much uncertainty. These results are a demonstration of the high-mass nature of the system, and the similarities of the star-formation process in the low-mass and high-mass regimes viz. the presence of a disk-accretion stage. The companion is located along the dark lane, consistent with it being in the equatorial/disk plane, indicating a disk-accretion setting for massive, multiple, star-formation.