Predictions for an unseen third planet in the WISPIT 2 system

Abstract

We predict the mass and semi-major axis of a currently unseen but hypothesised planet in the WISPIT 2 system based on the location of the ring observed by ALMA at 144.4 au. Using findings from previous hydrodynamical models, we predict that a ~0.2-1 $M_{Jup}$ planet may exist at ~ 100-120 au. We also demonstrate that the ring seen in VLT/SPHERE observations at 96.7 au is consistent with the mass and semi-major axis of WISPIT 2b and confirm that WISPIT 2b cannot be the cause of the ALMA ring. We also discuss how future observations of the system's gas component may help constrain these predictions better, and note that this third planet in WISPIT 2 may be discoverable using upcoming JWST/NIRCam observations or Gaia data release 4 (DR4).