Bo-Ting Shen(Academia Sinica, Institute of Astronomy and Astrophysics, Taipei, Taiwan);Ya-Wen Tang(Academia Sinica, Institute of Astronomy and Astrophysics, Taipei, Taiwan)
Planets form within disks. With ALMA, we can probe into protoplanetary systems to study planets formation. Asymmetric features within disks might provide the indirect evidences of embedded object. We analyze the disk structures of MWC 758 traced with continuum emission at wavelengths of 0.9 mm with 0.18" angular resolution and 0.09 mJy/beam in sensitivity with robust weighting and 0.12" angular resolution and 0.33 mJy/beam in sensitivity with superuniform (SU) weighting. We split the dust ring into segments by Azimuth to study the disk structure. We fit two Gaussian functions to the intensity versus radius profile of each segment, and analyze the best-fit parameters as a function of Azimuth. We describe the disk geometry with peak locations determined by the Gaussian fit. We found asymmetry and identify three structures. Among the three, two are dust clumps at different radius with similar peak intensity profile and spiral-like arc. The third feature is spiral-like structure located at southeast. We compare our spirals with the spirals seen in the near-infrared (NIR) polarized intensity. The southeastern spiral seen in the 0.9 mm continuum is co-located with one of the NIR spirals, while the northwestern spiral appears at a larger radius from the other NIR spiral. Such a spacial correlation of spirals seen at mm and NIR wavelengths can be explained by disk geometry. Possible origins of the three features at 0.9 mm will be discussed.