2016ApJ...831..200W

Transitional disks show a lack of excess emission at infrared wavelengths due to a large dust cavity, that is often corroborated by spatially resolved observations at ∼ mm wavelengths. We present the first spatially resolved ∼ mm-wavelength images of the disk around the Herbig Ae/Be star, HD 97048. Scattered light images show that the disk extends to ≃640 au. ALMA data reveal a circular-symmetric dusty disk extending to ≃350 au, and a molecular disk traced in CO J = 3-2 emission, extending to ≃750 au. The CO emission arises from a flared layer with an opening angle ≃30deg-40deg. HD 97048 is another source for which the large (∼ mm-sized) dust grains are more centrally concentrated than the small (∼µm-sized) grains and molecular gas, likely due to radial drift. The images and visibility data modeling suggest a decrement in continuum emission within ≃50 au, consistent with the cavity size determined from mid-infrared imaging (34 ± 4 au). The extracted continuum intensity profiles show ring-like structures with peaks at ≃50, 150, and 300 au, with associated gaps at ≃100 and 250 au. This structure should be confirmed in higher-resolution images (FWHM ≃ 10-20 au). These data confirm the classification of HD 97048 as a transitional disk that also possesses multiple ring-like structures in the dust continuum emission. Additional data are required at multiple and well-separated frequencies to fully characterize the disk structure, and thereby constrain the mechanism(s) responsible for sculpting the HD 97048 disk.