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Title:

            SMA Observation of the Circumstellar Disk of Herbig Ae Star AB Aur

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Authors:

Shin-Yi Lin, National Tsing Hua University, Taiwan

Nagayoshi Ohashi, Academia Sinica Institute of Astronomy and Astrophysics(ASIAA)

Jeremy Lim, ASIAA

Paul Ho, Harvard-Smithsonian Center for Astrophysics

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Abstract:

            The circumstellar dust disk of the Herbig Ae star AB Aurigae has been found to exhibit complex spiral-like structures in the near-IR. Here, we present maps of the disk in both 12CO (3-2) and dust continuum at 345GHz with the SMA at an angular resolution as high as ~1" (144AU). The CO emission has an overall dimension of ~1000AUx860AU, and exhibits a velocity gradient along its major axis consistent with a rotating disk with a deprojected maximum velocity of 2.8km/s at 500AU. The spatial-kinematic structure of the CO emission, however, cannot be fit by a uniform disk in Keplerian rotation.  The continuum emission has a maximum overall dimension of 670AU, and traces a dust disk that is smaller than the CO disk; this disk has an estimated total gas + dust mass of 0.016 solar mass. The continuum emission does not peak at the center of the disk, but instead exhibits several distinct peaks that appear to coincide with bright features in the near-IR image, in particular the brightest spiral arm. At least one of the continuum peaks has a counterpart in CO. The disk of AB Aur is therefore quite different from the uniform Keplerian disks seen around many lower mass T Tauri stars. We are currently constructing a model to explain our results based on the idea that gravitational instabilities or a giant planet may excite the spiral pattern seen in the disk of AB Aur.

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