Exoplanets & Exomoons

Statistics of Magrathea Exoplanets Beyond The Main Sequence. Simulating The Long-term Evolution Of Circumbinary Giant Planets With TRES

By Keith Cowing
Status Report
July 8, 2023
Filed under , , , ,
Statistics of Magrathea Exoplanets Beyond The Main Sequence. Simulating The Long-term Evolution Of Circumbinary Giant Planets With TRES
Population A: overview of the distributions of Magrathea systems in the parameter space. Solid histograms represent the Magrathea parameters at one Hubble time, while the dashed lines show their initial distributions. The “out” subscript denotes the planetary parameters (blue distributions). The dotted grey lines, instead, show the initial distributions for the whole population, not restricted to the Magratheas. — astro-ph.EP

Notwithstanding the tremendous growth of the exoplanetary field in the last decade, limited attention has been paid to the planets around binary stars. Circumbinary planets (CBPs) have been discovered primarily around Main Sequence (MS) stars. No exoplanet has been found orbiting double white dwarf (DWD) binaries yet.

We modelled the long-term evolution of CBPs, throughout the life stages of their hosts, from MS to white dwarf (WD). Our goal is to provide the community with both theoretical constraints on CBPs evolution beyond the MS and the occurrence rates of planet survival. We further developed the publicly available Triple Evolution Simulation (TRES) code, implementing a variety of physical processes affecting substellar bodies. We then used this code to simulate the evolution, up to one Hubble time, of two synthetic populations of circumbinary giant planets. Each population has been generated using different priors for the planetary orbital parameters.

In our simulated populations we identified several evolutionary categories, such as survived, merged, and destabilised systems. Our primary focus is those systems where the planet survived the entire system evolution and orbits a DWD binary, which we call “Magrathea” planets. We found that a significant fraction of simulated CBPs survive and become Magratheas. In the absence of multi-planet migration mechanisms, this category of planets is characterised by long orbital periods.

Magrathea planets are a natural outcome of triple systems evolution, and they could be relatively common in the Galaxy. They can survive the death of their binary hosts if they orbit far enough to avoid engulfment and instabilities. Our results can ultimately be a reference to orient future observations of this uncharted class of planets and to compare different theoretical models.

Gabriele Columba, Camilla Danielski, Andris Dorozsmai, Silvia Toonen, Manuel Lopez Puertas

Comments: Accepted for publication on A&A. 17 pages (+7 in the appendix), 8 figures (+9 in the appendix), 3 tables
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2305.07057 [astro-ph.EP] (or arXiv:2305.07057v1 [astro-ph.EP] for this version)
Focus to learn more
Submission history
From: Gabriele Columba
[v1] Thu, 11 May 2023 18:00:04 UTC (2,435 KB)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻