HD 148797 hosts two ~40 ME, ~8.3 RE, low-density savanna planets near a 1.619 period ratio whose anti-correlated TTVs yield masses and support compact multi-planet architectures as typical in the savanna.
Resonance in the K2-19 system is at odds with its high reported eccentricities
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abstract
K2-19 hosts a planetary system composed of two outer planets, b and c, with size of $7.0\pm 0.2~R_\oplus$ and $4.1\pm0.2~R_\oplus$ , and an inner planet, d, with a radius of $1.11\pm 0.05 R_\oplus$. A recent analysis of Transit-Timing Variations (TTVs) suggested b and c are close to but not in 3:2 mean motion resonance (MMR) because the classical resonant angles circulate. Such an architecture challenges our understanding of planet formation. Indeed, planet migration through the protoplanetary disk should lead to a capture into the MMR. Here, we show that the planets are in fact, locked into the 3:2 resonance despite circulation of the conventional resonant angles and aligned periapses. However, we show that such an orbital configuration cannot be maintained for more than a few hundred million years due to the tidal dissipation experienced by planet d. The tidal dissipation remains efficient because of a secular forcing of the innermost planet eccentricity by planets b and c. While the observations strongly rule out an orbital solution where the three planets are on close to circular orbits, it remains possible that a fourth planet is affecting the TTVs such that the four planet system is consistent with the tidal constraints.
fields
astro-ph.EP 1years
2026 1verdicts
CONDITIONAL 1representative citing papers
citing papers explorer
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HD 148797: A bright F-type star with two moderate-period low-density sub-Jovian planets. Compact multi-planet architectures are common in the Neptunian savanna
HD 148797 hosts two ~40 ME, ~8.3 RE, low-density savanna planets near a 1.619 period ratio whose anti-correlated TTVs yield masses and support compact multi-planet architectures as typical in the savanna.