Dynamics and Formation of the Near-resonant K2-24 System: Insights from Transit-timing Variations and Radial Velocities

Petigura, Erik A.; Benneke, Björn; Batygin, Konstantin; Fulton, Benjamin J.; Werner, M. W.; Krick, Jessica; Gorjian, Varoujan; Sinukoff, Evan; Deck, Katherine M.; Mills, Sean M.; Deming, Drake

doi:10.3847/1538-3881/aaceac

Cited by 35 publications

(77 citation statements)

References 71 publications

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“…This sample also includes Kepler-18d (Cochran et al 2011;Petigura et al 2017b) and K2-24c . Petigura et al (2018) suggest a formation scenario for the latter planet wherein the disk dissipates just as the planet begins to enter runaway accretion. Lee (2019) show that the sub-Saturn population can indeed be explained by the timing of disk dispersal, but they note as a prerequisite that their cores must be massive enough to trigger runaway accretion during the disk lifetime, 10M ⊕ .…”

Section: A Possible Formation Scenario For Kepler-177mentioning

confidence: 98%

Diffuser-assisted Infrared Transit Photometry for Four Dynamically Interacting Kepler Systems

Vissapragada

Jontof-Hutter

Shporer

et al. 2020

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We present ground-based infrared transit observations for four dynamically interacting Kepler planets, including Kepler-29b, Kepler-36c, KOI-1783.01, and Kepler-177c, obtained using the Wide-field Infrared Camera on the Hale 200" telescope at Palomar Observatory. By utilizing an engineered diffuser and custom guiding software, we mitigate time-correlated telluric and instrumental noise sources in these observations. We achieve an infrared photometric precision comparable to or better than that of space-based observatories such as the Spitzer Space Telescope, and detect transits with greater than 5σ significance for all planets aside from Kepler-36c. For Kepler-177c (J = 13.9) our measurement uncertainties are only 1.2× the photon noise limit and 1.9 times better than the predicted photometric precision for Spitzer IRAC photometry of this same target. We find that a single transit observation obtained 4 − 5 years after the end of the original Kepler mission can reduce dynamical mass uncertainties by as much as a factor of three for these systems. Additionally, we combine our new observations of KOI-1783.01 with information from the literature to confirm the planetary nature of this system. We discuss the implications of our new mass and radius constraints in the context of known exoplanets with low incident fluxes, and we note that Kepler-177c may be a more massive analog to the currently known super-puffs given its core mass (4.2±0.8M ⊕ ) and large gas-to-core ratio (2.5±0.2). Our demonstrated infrared photometric performance opens up new avenues for ground-based observations of transiting exoplanets previously thought to be restricted to space-based investigation.

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Section: A Possible Formation Scenario For Kepler-177mentioning

confidence: 98%

Diffuser-assisted Infrared Transit Photometry for Four Dynamically Interacting Kepler Systems

Vissapragada

Jontof-Hutter

Shporer

et al. 2020

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“…Following Petigura et al (2018a), we incorporated the RV mass constraints as Gaussian priors on the planet masses. We checked that this treatment is justified by verifying that the posteriors on K 1 , K 2 , and K 3 (Section 4.1) are Gaussian and uncorrelated.…”

Section: Photo-dynamical Analysismentioning

confidence: 99%

K2-19b and c are in a 3:2 Commensurability but out of Resonance: A Challenge to Planet Assembly by Convergent Migration

Petigura

Livingston

Batygin

et al. 2019

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K2-19b and c were among the first planets discovered by NASA's K2 mission and together stand in stark contrast with the physical and orbital properties of the solar system planets. The planets are between the size of Uranus and Saturn at 7.0 ± 0.2 R ⊕ and 4.1 ± 0.2 R ⊕ , respectively, and reside a mere 0.1% outside the nominal 3:2 mean-motion resonance. They represent a different outcome of the planet formation process than the solar system, as well as the vast majority of known exoplanets. We measured the physical and orbital properties of these planets using photometry from K2 , Spitzer , and groundbased telescopes, along with radial velocities from Keck/HIRES. Through a joint photodynamical model, we found that the planets have moderate eccentricities of e ≈ 0.20 and well-aligned apsides ∆ ≈ 0 deg. The planets occupy a strictly non-resonant configuration: the resonant angles circulate rather than librate. This defies the predictions of standard formation pathways that invoke convergent or divergent migration, both of which predict ∆ ≈ 180 deg and eccentricities of a few percent or less. We measured masses of M p,b = 32.4 ± 1.7 M ⊕ and M p,c = 10.8 ± 0.6 M ⊕ . Our measurements, with 5% fractional uncertainties, are among the most precise of any sub-Jovian exoplanet. Mass and size reflect a planet's core/envelope structure. Despite having a relatively massive core of M core ≈ 15 M ⊕ , K2-19b is envelope-rich, with an envelope mass fraction of roughly 50%. This planet poses a challenge to standard models core-nucleated accretion, which predict that cores 10 M ⊕ will quickly accrete gas and trigger runaway accretion when the envelope mass exceeds that of the core.

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“…Modeling these TTVs can give mass constraints on the planets; however, with low signal-to-noise (S/N) data a mass-eccentricity degeneracy often remains (Lithwick et al 2012;Deck & Agol 2015). These degeneracies can sometimes be broken by RV data that provide a complementary constraint (e.g., Petigura et al 2018), or by a strong prior on eccentricity (Hadden & Lithwick 2017). We study Kepler-65 and Kepler-25 with a photodynamical model which produces synthetic RV and photometric data generated by the N-body interactions of simulated planets and compares it to the observed data to extract planetary orbital elements, masses, and radii self-consistently.…”

Section: Methodsmentioning

confidence: 99%

Long-period Giant Companions to Three Compact, Multiplanet Systems

Mills

Howard

Weiss

et al. 2019

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Understanding the relationship between long-period giant planets and multiple smaller short-period planets is critical for formulating a complete picture of planet formation. This work characterizes three such systems. We present Kepler-65, a system with an eccentric (e = 0.28 ± 0.07) giant planet companion discovered via radial velocities (RVs) exterior to a compact, multiply-transiting system of sub-Neptune planets. We also use precision RVs to improve mass and radius constraints on two other systems with similar architectures, Kepler-25 and Kepler-68. In Kepler-68 we propose a second exterior giant planet candidate. Finally, we consider the implications of these systems for planet formation models, particularly that the moderate eccentricity in Kepler-65's exterior giant planet did not disrupt its inner system.

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Dynamics and Formation of the Near-resonant K2-24 System: Insights from Transit-timing Variations and Radial Velocities

Cited by 35 publications

References 71 publications

Diffuser-assisted Infrared Transit Photometry for Four Dynamically Interacting Kepler Systems

Diffuser-assisted Infrared Transit Photometry for Four Dynamically Interacting Kepler Systems

K2-19b and c are in a 3:2 Commensurability but out of Resonance: A Challenge to Planet Assembly by Convergent Migration

Long-period Giant Companions to Three Compact, Multiplanet Systems

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