Verify the apsidal precession of TOI-1355 b

Verify whether the argument of periastron of the eccentric hot Jupiter TOI-1355 b changes over time, thereby determining whether apsidal precession accompanies the detected nodal precession.

Background

The paper detects nodal precession in TOI-1355 b through a measured increase in its transit impact parameter, quantified by db/dt. The authors also fit for temporal changes in the argument of periastron, but the available observations do not establish such a change. Confirming or ruling out apsidal precession would help distinguish the dynamical contributions of relativistic effects, tidal distortion, and stellar rotational distortion to the system’s orbital evolution.

The argument of periastron is relevant to interpreting the coupled evolution of the planet’s orbital geometry and eccentricity. Additional high-precision transit and phase-curve observations could test whether the fitted change in the argument of periastron represents a genuine secular effect.

References

The nodal precession of this hot Jupiter was detected as a change in $b$ over time ($db/dt=0.01633{+0.00081}_{-0.00076}$ year${-1}$ in the Cloud-free Case), although the change in $\omega$ could not be verified.

— Discovery of an Eccentric Hot Super-Jupiter Leaving the Transiting Geometry of the Early-A-type star TOI-1355  (2608.17387 - Watanabe et al., 18 Aug 2026) in Section 6.2, “Nodal Precession”