Gas kinematics refers to the study of motion of disk gas as traced by spectral line observations (for example through CO molecular line observations). The particularly notable aspect of gas kinematics is the observations of velocity kinks in the channel maps of observations of disks. These are hypothesized to be caused by an embedded planet
To verify this hypothesis, we can try exploring other ways a planet might also interact with the disk. Possibilities include carving out gas gaps and generating dust spirals. If we can manage to observe the gas-gaps and dust-spirals exactly in the way the theory predicts, we can have greater confidence on our embedded planet hypothesis. For example, gas-gaps can be modeled through the planet-disk torques.
Criteria for detection
According to Pinte et al. (2023)1, following criteria have been established to claim a detection of an embedded planet in a disk
- A localized velocity disturbance (kink/Doppler-flip) co-located with a gap (ideally in multiple tracers)
- Detected in multiple lines (sampling vertical structure) and resolved in velocity
- A localized enhancement of line broadening.
Until now, there is only the candidate in HD163296 at 260 AU which satisfies all of the criteria.
References
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Kinematic Structures in Planet-Forming Disks: https://ui.adsabs.harvard.edu/abs/2023ASPC..534..645P ↩