A 2 au Resolution View by ALMA of the Planet-hosting WISPIT 2 Disk

We present deep, high-spatial-resolution interferometric observations of 0.88 mm continuum emission from the
TYC 5709-354-1 system, hereafter WISPIT 2, obtained with the goal of detecting circumplanetary emission in the
vicinity of the newly discovered WISPIT 2b planet. Observations with the most extended baseline configuration
offered by the Atacama Large Millimeter/submillimeter Array, achieving an angular resolution of 25 × 17 mas
(3.3 × 2.2 au), revealed a single, narrow ring with a deprojected radius of 144.4 au and width of 7.2 au, and no
evidence of circumplanetary emission within the cavity. Injection and recovery tests demonstrate that these
observations can rule out pointlike emission at the location of WISPIT 2b brighter than ≈ 45 μJy at the 3σ level.
While these data can rule out PDS 70 c-like circumplanetary emission, the upper limit is consistent with empirical
mass–flux relationships extrapolated from the stellar regime. Visibility modeling of the continuum ring confirms
that WISPIT 2b lies significantly interior to the millimeter dust ring, raising doubts about the ability of WISPIT 2b
to be the only driver of the dust structure. Possible solutions include either another lower-mass companion,
residing between WISPIT 2b and the cavity edge, likely in the gap seen by SPHERE at ∼130 au, or that
WISPIT 2b is either substantially more massive than estimates based on IR photometry (∼15 MJup) or on a
moderately eccentric orbit. The combination of observations sensitive to the gas and dust distributions on larger
spatial scales and dedicated hydrodynamical modeling will help differentiate between scenarios.