Resolving and probing the circumstellar disk of the Herbig Ae star MWC 480 at λ = 1.4 mm: Evolved dust?

We present high-resolution 0.″45 x 0.″32 observations from the BIMA array toward the Herbig Ae system MWC 480 in the λ = 1.4 mm dust continuum. We resolve a circumstellar disk of radius ∼170 AU and constrain the disk parameters by comparing the observations to flat-disk models. These results show that the typical fit parameters of the disk, such as the mass, M_D ∼0.04-0.18 M_⊙, and the surface density power-law index, p = 0.5 or 1, are comparable to those of the lower mass T Tauri stars. The dust in the MWC 480 disk can be modeled as processed dust material (β ≈ 0.8), similar to the Herbig Ae star CQ Tau disk; the fitted disk parameters are also consistent with less evolved dust (β ≈ 1.2). The possibility of grain growth in the MWC 480 circumstellar disk is supported by the acceptable fits with β ≈ 0.8. The surface density power-law profiles of p = 0.5 and p = 1 can be easily fitted to the MWC 480 disk; however, a surface density power-law profile similar to the minimum mass solar nebula model p = 1.5 is ruled out at an 80% confidence level.