Title: ALMA Observations of Disk Properties across the Brown Dwarf Boundary from the Taurus Boundary of Stellar/Substellar 
(TBOSS) Survey

Authors: Gerrit van der Plas, Kimberly Ward-Duong, Jennifer Patience, Joanna Bulger, Francois Menard, Christophe Pinte, Paul 
Harvey, Simon Casassus, Geoff Bryden, Alan Jackson

Abstract:
We report 885um ALMA continuum flux densities for 24 low mass members of Taurus, spanning the stellar/substellar boundary with 
spectral types from M4 to M7.75. Of the 24 targets, 22 are detected at levels ranging from 1.0 mJy/beam to 55.6 mJy/beam. These 
detections will be compared with CO measurements to investigate disk evolution and structure. The two continuum non-detections 
are transition disk systems, although other transition disks in the sample are detected. Applying standard scaling laws or radiative 
transfer modeling to convert the ALMA continuum measurements to masses yields dust mass estimates ranging from  ~0.3MEarth 
to ~20MEarth. The disk masses inferred from the ALMA data show a trend of declining dust mass with central object mass when 
combined with results from submillimeter surveys of more massive Taurus members. The substellar disks appear as part of a 
continuous sequence and not a distinct population. Compared to older Upper Sco members with similar masses across the 
substellar limit, the Taurus disks are brighter and more massive. The mass inventory of solids in small particles in the Taurus disks 
typically exceeds the average heavy-element mass in Kepler short period planets, however the dust in the Taurus disks is 
distributed across the full disk radius. Assuming a gas:dust ratio of 100:1, only a small number of the low mass stars and brown 
dwarfs have a total disk mass amenable to giant planet formation, consistent with the low frequency of giant planets orbiting M-
dwarfs.