Presence of additional planets in WD 1856+534 outside current TTV constraints

Determine whether WD 1856+534 hosts smaller close-in planets and/or more distant, larger planets that remain unconstrained by the present transit timing variation analysis, by detecting such bodies or conclusively excluding them as perturbers.

Background

Using an extended transit timing baseline and TTVFast simulations, the authors rule out companion planets above certain mass–period thresholds (e.g., >4.1 MJ for periods <1500 days).

However, the analysis does not exclude lower-mass close-in companions or larger bodies at greater separations, leaving open the possibility of undetected perturbers that could have driven earlier migration.

References

It is important to note that while our data allow us to rule out a large close-in planet as the perturber, we cannot yet rule out smaller close-in planets and larger planets at greater distances.

— Transit Timing of the White Dwarf-Cold Jupiter System WD 1856+534  (2511.21611 - Gendreau-Distler et al., 26 Nov 2025) in Section 5, Conclusions