The conditions and evolution of protoplanetary disks in multiple systems can be considerably different from those around single stars , which may have important consequences for planet formation .
We present Very Large Array ( VLA ) 8.8 mm ( 34 GHz ) and 5 cm ( 6 GHz ) observations of the quadruple system HD 98800 , which consists of two spectroscopic binary systems ( Aa-Ab , Ba-Bb ) .
The Ba-Bb pair is surrounded by a circumbinary disk , which is usually assumed to be a debris disk given its \sim 10 Myr age and the lack of near infrared excess .
The VLA 8.8 mm observations resolve the disk size ( 5-5.5 au ) and its inner cavity ( \approx 3 au ) for the first time , making it one of the smallest disks known .
Its small size , large fractional luminosity , and millimeter spectral index consistent with blackbody emission support the idea that HD 98800 B is a massive , optically thick ring that may still retain significant amounts of gas .
The disk detection at 5 cm is compatible with free-free emission from photoionized material .
The diskless HD 98800 A component is also detected , showing partial polarization at 5 cm that is compatible with nonthermal chromospheric activity .
We propose that tidal torques from Ba-Bb and A-B have stopped the viscous evolution of the inner and outer disk radii , and the disk is evolving via mass loss through photoevaporative winds .
This scenario can explain the properties and longevity of HD 98800 B as well as the lack of a disk around HD 98800 A , suggesting that planet formation could have more time to proceed in multiple systems than around single stars in certain system configurations .