Observations of the Herbig Ae star AB Aur using the Submillimeter Array

摘要

We present recent observations of the circumstellar disk aroundthe Herbig Ae star AB Aur carried out in ~(12)CO(J =3 — 2) and in the dust con-tinuum at 850 pm using the Submillimeter Array. The disk is spatially resolvedin both the ~(12)CO (J = 3 — 2) and the 850 μmimages at an angular resolution of 1". The SMA 850 μm dust continuum image of the circumstellar disk reveals acentral cavity in the disk with an estimated size of ~100 AU. Remarkably, debrisdisks often show similar kinds of central cavities with sizes of 50-100 AU. The~(12)CO(J.=3-2) image of the disk shows a significant peak at the root of mostprominent spiral arm seen in the Subaru image, as well as another peak at thedisk center, making the geometry of the ~(12)CO disk very non-axisymmetric withrespect to the disk center. The position-velocity diagram of the ~(12)CO emissionshows velocity structures that are significantly non-axisymmetric with respectto the disk center, as well as a velocity gradient along the disk major axis. Theseresults show that the circumstellar disk around AB Aur is remarkably differentfrom Keplerian disks often observed around T Tauri stars and Herbig Ae stars.Such differences could be due to the spiral arms in the disk, whereas it might bedifficult for gravitational instabilities to create the non-axisymmetric structuresseen in the SMA images.