Sites of Planet Formation in Binary Systems. II. Double the Disks in DF Tau

TL;DR

This study uses ALMA observations to reveal that the binary star system DF Tau hosts two disks, challenging previous assumptions about disk presence and evolution in binary systems, with implications for planet formation.

Contribution

It provides the first ALMA detection of two nearly-equal disks in DF Tau, highlighting uneven disk dissipation in a coeval binary system.

Findings

ALMA maps show two nearly-equal brightness disks in DF Tau.

The secondary's inner disk appears absent despite coeval formation.

Uneven disk dissipation may influence planet formation processes.

Abstract

This article presents the latest results of our ALMA program to study circumstellar disk characteristics as a function of orbital and stellar properties in a sample of young binary star systems known to host at least one disk. Optical and infrared observations of the eccentric, ~48-year period binary DF Tau indicated the presence of only one disk around the brighter component. However, our 1.3 mm ALMA thermal continuum maps show two nearly-equal brightness components in this system. We present these observations within the context of updated stellar and orbital properties which indicate that the inner disk of the secondary is absent. Because the two stars likely formed together, with the same composition, in the same environment, and at the same time, we expect their disks to be co-eval. However the absence of an inner disk around the secondary suggests uneven dissipation. We consider several processes which have the potential to accelerate inner disk evolution. Rapid inner disk dissipation has important implications for planet formation, particularly in the terrestrial-planet-forming region.