a ) 13 grain growth-dominated disks (accreting objects with α ≲ 0). 

b ) 4 giant planet forming disks (accreting objects with α ≳ 0). 

c ) 5 photoevaporating disks (non-accreting objects with disk mass < 2.5 M$_{JUP}$ , but L$_{D}$/L$_{∗}$ > 10 − $^{3}$) 

d ) 4 debris disks (non-accreting objects with disk mass < 2.5 M$_{JUP}$ and L$_{D}$/L$_{∗}$ < 10 − $^{3}$) 

e ) 4 circumbinary disks (a binary tight enough to accommodate both components within the inferred inner hole). 

The total number of objects listed add up to 30 instead of 26 because 4 objects fall into two categories. Sources # 12 and 23 are considered both debris disks and circumbinary disks. Object #24 has been classified as both a circumbinary disk and a photoevaporating disk, while object # 27 has been classified as both a circumbinary disk and a grain growth dominated disk. These last two objects are triple systems and their classification depends on whether the IR excess is associated with the tight components of the systems or with the wide components. 

The “disk types” for our targets are listed in Table 3. All of our objects should be considered to be candidates for the categories listed above. The current classification represents our best guess given the available data. Only followup observations and detailed modeling will firmly establish the true nature of each object. An important caveat of this classification is the lack of constraints for most of the sample on stellar companions within ≲ 8 AU, a range where ∼ 30% of all stellar companions are expected to lay (Duquennoy & Mayor, 1991; Ratzka et al. 2005). Future radial velocity observations are very likely to increase the number of objects in the circumbinary disk category. 

While it is tempting to speculate that the “disk types” a through d represent an evolutionary sequence, starting with a “full disk” (i.e., a “full disk” that undergoes grain growth followed by giant planet formation, followed by photoevaporation leading to a debris 

