Kepler-60 (italicised) or maybe KOI-2086 is another exoplanet-transit system. It doesn't have its own page on Wiki possibly on account that the planets aren't fun for SF writers. The three found so far are all subNeptunians well in the Venus zone or worse. Maybe there's a fourth in an outer, better spot. Ehh.
I'm interested because it has a Laplace-like resonance which isn't binary. b and c rock 5:4; c and d are 4:3. The base maths can be had from John C. B. Papaloizou "Three body resonances in close orbiting planetary systems: tidal dissipation and orbital evolution" (arXiv; IJA Apr 2015, 291f if you want to pay for it). Goździewski's quartet thence extrapolated: here might be full 5:4:3 rather than a chain. This has implications for migration-theory because migrations break multibody resonances into chains of pairs, or into no true resonance at all. I mean - look at the Grand Tack between Jupiter and Saturn, and the havoc they raised.
Those calculations were based on the data at hand in 2015. Already the masses were fairly-well constrained since these are transits so sin i cannot be must less than 1. The lightcurve was, however, noisy - too noisy to decide which resonance. Since then the assumed values have been corrected according to the Gaia telescope's DataRelease2. Since then, DR3 came out. No, I won't download these tables. Then there's the line-by-line method.
Which resonance, 5:4+4:3 or 5:4:3, would constrain the mass better still. Goździewski et al. fed their data into some 2003 algo called "Mean Exponential Growth factor of Nearby Orbits".
I don't know that I need to pull this like I'd pulled (say) Lambert two years ago. I just know at this point that I must be a reporter rather than a speculator. Papaloizou on the other hand looks interesting for tracking the 4:3+3:2 of Kepler-90def... or what I want for Jupiter.
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