Probing Dust in the MWC 480 Disk from Millimeter to Centimeter Wavelengths

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Abstract
We present deep, high-resolution (∼100 mas) Karl G. Jansky Very Large Array Ka -band (9.1 mm) observations of the disk around MWC 480 and infer dust properties through a combined analysis with archival Atacama Large Millimeter/submillimeter Array data at 0.87, 1.17, 1.33, and 3.0 mm. The prominent dust ring at 95 au (B95) is detected at 9.1 mm for the first time, while the faint outer ring at 160 au is not revealed. Through nonparametric visibility modeling, we identified two new annular features: a plateau within 20–50 au across all wavelengths, and a shoulder exterior to the B95 ring at 0.87, 1.17, and 1.33 mm, consistent with signatures of planet–disk interaction. We find that the width of the B95 ring remains constant across wavelengths, suggesting that fragmentation dominates over radial diffusion or that unresolved substructure is present within the ring. Resolved spectral modeling yields two families of dust solutions that reproduce the observations equally well: compact grains or highly porous (90%) grains, with carbonaceous components dominated by refractory organics or amorphous carbon, respectively. The inferred maximum grain sizes peak at the locations of the two rings and reach centimeter within the B95 ring. The total dust masses are 86 0 − 78 + 95 M ⊕ / 150 0 − 330 + 440 M ⊕ (large/small-grain solution in inner disk) and 23 0 − 13 + 14 M ⊕ for the two dust mixtures. The B95 ring alone contains 10 0 − 5 + 5 M ⊕ and 4 3 − 2 + 2 M ⊕ , respectively, sufficient to assemble the cores of giant planets. Finally, we highlight the power of broadband, multiwavelength observations in placing better constraints on dust composition and porosity in protoplanetary disks.
Funding Information
  • MOST ∣ National Natural Science Foundation of China (12573031)
  • MOST ∣ National Natural Science Foundation of China (12173003)

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