Bad news for fans of post-common envelope binary timing

Pulley et al. "Eclipse timing variations in post-common envelope binaries: Are they a reliable indicator of circumbinary companions?"
https://arxiv.org/abs/2206.06919

Failures of the planetary models to predict subsequent O-C variations in HW Vir, HS0705+6700 (V470 Cam), NSVS 14256825, NN Ser, RR Cae, DE CVn. NY Vir survives, probably by virtue of there not being enough time since the last published model. The systems 2MASS J19383260+4603591, KIC 10544976 and OGLE-GD-ECL-11388 are listed in table 1 but not otherwise studied in this paper.

Getting the very strong impression that none of the PCEB planets should be regarded as secure.

Lazarus wrote:

Getting the very strong impression that none of the PCEB planets should be regarded as secure.

Strongly agreed. I'm not at all surprised by this result.

Some “better” news concerning at least one new CV system: QZ Serpentis

Testing the third body hypothesis in the Cataclysmic Variables LU Camelopardalis, QZ Serpentis, V1007 Herculis and BK Lyncis

Quote :

Some Cataclysmic Variables (CVs) exhibits a very long photometric period (VLPP). We calculate the properties of a hypothetical third body, initially assumed on circular--planar orbit, by matching the modelled VLPP to the observed one of four CVs studied here: {\sl LU Camelopardalis} (LU Cam), QZ Serpentis (QZ Ser), V1007 Herculis (V1007 Her) and BK Lyncis (BK Lyn). The eccentric and low inclination orbits for a third body are considered using analytical results. The chosen parameters of the binary components are based on the orbital period of each CV. The smallest corresponding semi-major axis permitted before the third body's orbit becomes unstable is also calculated. A first-order analytical post-Newtonian correction is applied, and the rate of precession of the pericentre is found, but it can not explain any of the observed VLPP. For the first time, we also estimate the effect of secular perturbations by this hypothetical third body on the mass transfer rate of such CVs. We made sure that the observed and calculated amplitude of variability was comparable too. The mass of the third body satisfying all constrains range from 0.63 to 97 Jupiter masses. Our results show further evidence supporting the hypothesis of a third body in three of these CVs, but only marginally in V1007 Her.

This seems the innermost circumbinary planet to date (a_(AB)b = 0.019 AUs for P = 1.04 d).

My reading of this is that this is a different situation to the post-common envelope eclipsing binary systems. This paper seems to suggest an inclination of about 30 degrees, and the new paper on the system seems to imply that the planet was inferred by modelling a long-term photometric variation as a reflected light phase curve. But I'm not really certain.