Follow-up Observations of Candidate White Dwarf Planets with MIRI

We report on second-epoch imaging of two candidate planet-hosting white dwarf (WD) stars, WD 2105−82 and WD 1202−232. Both stars showed evidence of resolved, planet-mass candidate companions in observations using the MIRI mid-infrared imager on JWST. WD 2105 also showed evidence of an infrared excess consistent with an unresolved 1.4 M J companion with an orbital separation of <4 au. Our second epoch observations confirm that the source of the excess shares common proper motion with the star. The excess is almost certainly due to a companion planet or debris disk. However, neither of the two resolved sources with projected separations of >1″ in the first epoch of JWST observations show measurable proper motion and are thus likely faint, unresolved background galaxies. We also search for common proper-motion companions out to hundreds of astronomical unit, but find no evidence of widely separated companions.