Planets at HW Virginis?

I set up the system with the parameters given in the paper in Gravity Simulator - it's unstable.

I'm unsurprised. I put the system into Celestia and the planets come pretty close. The paper suggests that the planets might be in a resonance configuration, might that spare them?

Beuermann et al. "The quest for companions to post-common envelope binaries: III. A reexamination of HW Virginis"

This time they take stability considerations into account, as well as new timing measurements.

Result is an inner companion with minimum mass 14.3 Jupiter masses, orbital period 12.7 years and an eccentric orbit (e=0.40±0.10), and an outer companion that may be a brown dwarf or low-mass star. The example orbital fit they give has a period of 55 years and a minimum mass of 65 times Jupiter, however there is only partial coverage of the orbit so it is not possible to pin down the parameters with certainty.

Horner et al. "A Dynamical Analysis of the Proposed Circumbinary HW Virginis Planetary System"

The previous paper came out while this one was with the referee but conclusions about the stability of the original solution are the same. They also note the unconstrained period of the outer companion in the Beuermann et al. paper raises doubts as to whether a 2 companion system is really what is going on.

So far it seems only NN Serpentis has held up as a multiplanet circumbinary system...

Lazarus wrote:

Horner et al. "A Dynamical Analysis of the Proposed Circumbinary HW Virginis Planetary System"

The previous paper came out while this one was with the referee but conclusions about the stability of the original solution are the same. They also note the unconstrained period of the outer companion in the Beuermann et al. paper raises doubts as to whether a 2 companion system is really what is going on.

So far it seems only NN Serpentis has held up as a multiplanet circumbinary system...

And what about RR Cae, DP Leo, UZ For and NY Vir?

RR Caeli, DP Leonis and NY Virginis are single planet systems. (RR Cae and NY Vir have trends that may indicate the presence of a second planet but this is still unconfirmed - I'm not aware this also applies to DP Leo). UZ Fornacis has not yet been subject to follow-up, and the best fit two-planet solutions are unstable as noted in the discovery paper.

New eclipse timings. New deviation from the previous model.

A new photometric and dynamical study of the eclipsing binary star HW Virginis
https://arxiv.org/abs/2106.15632

EPE has decided to list the additional second object too:

http://exoplanet.eu/catalog/hw_vir_(ab)_c/

New evidence about HW Vir's circumbinary planets from Hipparcos-Gaia astrometry and a reanalysis of the eclipse timing variations using nested sampling

Quote :

The post common-envelope eclipsing binary HW Virginis has had many circumbinary companions proposed based on eclipse timing variations. Each proposed solution has lacked in predictability and orbital stability, leaving the origin of the eclipse timing variations an active area of research. Leveraging the catalogue of Hipparcos and Gaia proper motion anomalies, we show there is slight evidence for a circumbinary companion orbiting HW Vir. We place an upper limit in mass for such a companion which excludes some previously claimed companions. We also apply this method to V471 Tauri and confirm the non-detection of a previously claimed brown dwarf. We adapt the kima nested sampling code to analyse eclipse timing variations and re-analyse archival data on HW Vir, varying the order of the ephemeris that we fit for and the amount of the data that we use. Although signals are clearly present, we find two signals around 2500 and 4000 day periods that are not coherent between different chunks of the data, so are likely to not be of planetary origin. We analyse the whole dataset and find the best solution to contain four signals. Of these four we argue the outermost is the most compatible with astrometry and thus the most likely to be of planetary nature. We posit the other three pseudo-periodic signals are caused by physical processes on the white dwarf. The eventual release of the full Gaia epoch astrometry is a promising way to confirm whether circumbinary planets exist around HW Vir (and other similar systems), and explore white dwarf physics.