ALMA Reveals the Anatomy of the mm-sized Dust and Molecular Gas in the HD 97048 Disk
Walsh, Catherine, Juhász, Attila, Meeus, Gwendolyn, Dent, William R.~F., Maud, Luke T., Aikawa, Yuri, Millar, Tom J., & Nomura, Hideko
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 \ensuremath≈640 au. ALMA data reveal a circular- symmetric dusty disk extending to \ensuremath≈350 au, and a molecular disk traced in CO J = 3-2 emission, extending to \ensuremath≈750 au. The CO emission arises from a flared layer with an opening angle \ensuremath≈30°-40°. HD 97048 is another source for which the large (̃ mm-sized) dust grains are more centrally concentrated than the small (̃\ensuremathμm-sized) grains and molecular gas, likely due to radial drift. The images and visibility data modeling suggest a decrement in continuum emission within \ensuremath≈50 au, consistent with the cavity size determined from mid-infrared imaging (34 \ensuremath± 4 au). The extracted continuum intensity profiles show ring-like structures with peaks at \ensuremath≈50, 150, and 300 au, with associated gaps at \ensuremath≈100 and 250 au. This structure should be confirmed in higher-resolution images (FWHM \ensuremath≈ 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.