Resolving Structure In The Debris Disk Around Hd 206893 With Alma

Debris disks are tenuous, dusty belts surrounding main-sequence stars generated by collisions between planetesimals. HD 206893 is one of only two stars known to host a directly imaged brown dwarf orbiting interior to its debris ring, in this case at a projected separation of 10.4 au. Here we resolve structure in the debris disk around HD 206893 at an angular resolution of 0.'' 6 (24 au) and wavelength of 1.3 mm with the Atacama Large Millimeter/submillimeter Array (ALMA). We observe a broad disk extending from a radius of <51 au to 194(-2)(+13) au. We model the disk with a continuous, gapped, and double power-law model of the surface density profile and find strong evidence for a local minimum in the surface density distribution near a radius of 70 au, consistent with a gap in the disk with an inner radius of 63(-16)(+8) au and width 31(-7)(+11) au. Gapped structure has been observed in four other debris disks-essentially every other radially resolved debris disk observed with sufficient angular resolution and sensitivity with ALMA-and could be suggestive of the presence of an additional planetary-mass companion.