High-resolution studies of gas and dust around young intermediate-mass stars. II. Observations of an additional sample of Herbig Ae systems

In an earlier paper (Mannings & Sargent; Paper I), we presented evidence for disks of gas and dust associated with seven Herbig Ae stars, based on high-resolution interferometric millimeter-wave observations of continuum and molecular line emission. These systems are simultaneously high-mass analogs of the approximately solar-mass T Tauri stars and the evolutionary precursors of the prototypical main-sequence debris-disk sources beta Pic, alpha Lyr, and alpha PsA. Here we extend the original survey to include four additional Herbig Ae systems. We have also imaged two of the sources from Paper I at higher resolution. The new data are presented and analyzed, and are combined with the results from the earlier sample in order to address the properties of this class of circumstellar disk. Derived disk masses are indistinguishable from the masses of T Tauri disks. Although the combined sample is small, it seems likely that disk masses are essentially uncorrelated with stellar mass for pre-main-sequence stars of spectral type A0 and later.