We present sub-arcsecond thermal infrared imaging of HD 98800 , a young quadruple system composed of a pair of low-mass spectroscopic binaries separated by 0.8 ^ { \prime \prime } ( 38 AU ) , each with a K-dwarf primary .
Images at wavelengths ranging from 5 to 24.5 \mu m show unequivocally that the optically fainter binary , HD 98800B , is the sole source of a comparatively large infrared excess upon which a silicate emission feature is superposed .
The excess is detected only at wavelengths of 7.9 \mu m and longer , peaks at 25 \mu m , and has a best-fit black-body temperature of 150 K , indicating that most of the dust lies at distances greater than the orbital separation of the spectroscopic binary .
We estimate the radial extent of the dust with a disk model that approximates radiation from the spectroscopic binary as a single source of equivalent luminosity .
Given the data , the most-likely values of disk properties in the ranges considered are R _ { in } = { 5.0 } \pm 2.5 AU , \Delta R = 13 \pm 8 AU , \lambda _ { 0 } = { 2 } ^ { +4 } _ { -1.5 } \mu m , \gamma = 0 \pm 2.5 , and \sigma _ { total } = 16 \pm 3 AU ^ { 2 } , where R _ { in } is the inner radius , \Delta R is the radial extent of the disk , \lambda _ { 0 } is the effective grain size , \gamma is the radial power-law exponent of the optical depth , \tau , and \sigma _ { total } is the total cross-section of the grains .
The range of implied disk masses is 0.001–0.1 times that of the moon .
These results show that , for a wide range of possible disk properties , a circumbinary disk is far more likely than a narrow ring .