Follow-up Observations of Candidate White Dwarf Planets with MIRI

TL;DR

This study presents second-epoch JWST/MIRI observations of white dwarf stars, confirming a potential planet-mass companion around WD2105-82 and ruling out background objects, advancing understanding of planetary remnants around white dwarfs.

Contribution

First second-epoch imaging confirming candidate companions and ruling out background sources around white dwarf stars using JWST/MIRI.

Findings

Confirmed common proper motion of the infrared excess with WD2105-82.

Ruled out background galaxies as sources of the observed excess.

Detected no widely separated companions within hundreds of au.

Abstract

We report on second-epoch imaging of two candidate planet-hosting white dwarfs stars, WD2105-82 and WD1202-232. Both stars showed evidence of resolved, planet-mass candidate companions in observations using the MIRI mid-infrared imager on JWST. WD2105-82 also showed evidence of an infrared excess consistent with an unresolved 1.4 Jupiter mass 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 au, but find no evidence of widely separated companions.