Edasich
dK star
Number of posts : 2288
Location : Tau Ceti g - Mid Latitudes
Registration date : 2008-06-02
 | | Subject: A kinematically-detected planet candidate in a transition disk 5th January 2023, 5:27 am | |
| A kinematically-detected planet candidate in a transition disk - Quote :
- Transition disks are protoplanetary disks with inner cavities possibly cleared by massive companions, which makes them prime targets to observe at high resolution to map their velocity structure. We present ALMA Band 6 dust and gas observations of the transition disk around RXJ1604.3-2130 A, known to feature nearly symmetric shadows in scattered light. We study the 12CO line channel maps and moment maps of the line of sight velocity and peak intensity. We fit a Keplerian model of the channel-by-channel emission to study line profile differences, and produce deprojected radial profiles for all velocity components. The 12CO emission shows a cavity inwards of ∼56 au and within the dust continuum ring at 81 au. The azimuthal brightness variations in the 12CO line and dust continuum are broadly aligned with the shadows detected in scattered light observations. We find a strong localized non-Keplerian feature towards the west within the continuum ring (at R=41±10 au and PA=280±2∘). A tightly wound spiral is also detected which extends over 300∘ in azimuth, possibly connected to the localized non-Keplerian feature. Finally, a bending of the iso-velocity contours within the gas cavity indicates a highly perturbed inner region, possibly related to the presence of a misaligned inner disk. While broadly aligned with the scattered light shadows, the localized non-Keplerian feature cannot be solely due to changes in temperature. Instead, we interpret the kinematical feature as tracing a massive companion located at the edge of the dust continuum ring. We speculate that the spiral is caused by buoyancy resonances driven by planet-disk-interactions. However, this potential planet at ∼41 au cannot explain the gas-depleted cavity, the low accretion rate and the misaligned inner disk, suggesting the presence of another companion closer-in.
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