The Taurus Boundary of stellar/substellar (TBOSS) survey. II. Disk masses from ALMA continuum observations
We report 885 mu m ALMA continuum flux densities for 24 Taurus members spanning the stellar/substellar boundary with spectral types from M4 to M7.75. Of the 24 systems, 22 are detected at levels ranging from 1.0 to 55.7 mJy. The two nondetections are transition disks, though other transition disks in the sample are detected. Converting ALMA continuum measurements to masses using standard scaling laws and radiative transfer modeling yields dust mass estimates ranging from similar to 0.3 to 20M(circle plus). The dust mass shows a declining trend 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. Both Taurus and Upper Sco populations are consistent with an approximately linear relationship in M-dust to M-star, although derived power-law slopes depend strongly upon choices of stellar evolutionary model and dust temperature relation. The median disk around early-M stars in Taurus contains a comparable amount of mass in small solids as the average amount of heavy elements in Kepler planetary systems on short-period orbits around M-dwarf stars, with an order of magnitude spread in disk dust mass about the median value. Assuming a gas-to-dust ratio of 100:1, only a small number of 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.
NSF Graduate Research Fellowship DGE-1311230 NSF from the NRAO (Student Observing Support Program) SOSPA3-007 NSF Graduate Research Opportunities Worldwide supplemental award 13074525 NASA's Science Mission Directorate NNX15AD53G Jet Propulsion Laboratory's Strategic University Research Partnerships (SURP) program Millennium Science Initiative (Chilean Ministry of Economy) RC130007 FONDECYT 3140393 ANR of France ANR-16-CE31-0013 NASA NNX16AI31G NSF AST-1518332 National Aeronautics and Space Administration (NASA) NNX15AC89G NASA NExSS grant NNX15AD95G NASA NSF CONICYT
Artículo de publicación ISI
Quote ItemThe Astronomical Journal, 155:54 (26pp), 2018
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