We present observations of six isolated , pre-main-sequence , intermediate mass stars selected for shallow spectra at submillimeter wavelengths at 1.3 , 2.6 , 7.0 , and 36 millimeters from the IRAM PdBI and the VLA .
We analyze the new observations of these stars ( HD34282 , HD35187 , HD142666 , HD143006 , HD150193 , HD163296 ) together with similar observations of three additional stars from the literature ( CQ Tau , UX Ori , TW Hya ) , in the context of self-consistent irradiated disk models .
Our aim is to constrain the wavelength dependence of the dust opacity and the total dust mass in the disks .
The shallow wavelength dependence of the opacity is confirmed and for a few stars extended to significantly longer wavelengths .
For any plausible dust properties , this requires grain growth from interstellar sizes to maximum sizes of at least a few millimeters , and very likely to several centimeters or more .
For four of the stars ( HD34282 , HD163296 , CQ Tau , TW Hya ) , the millimeter emission has been spatially resolved , and the large disk radii ( > 100 AU ) rule out that high optical depths play a role .
The mass of dust that has been processed into large grains is substantial , and in some cases implies a disk mass comparable to the mass of the central star .