Kepler-11 is a Solar Twin: Revising the Masses and Radii of Benchmark Planets via Precise Stellar Characterization

Bedell, Megan; Bean, Jacob L.; Meléndez, Jorge; Mills, Sean M.; Fabrycky, Daniel C.; Freitas, Fabrício C.; Ramírez, Iván; Asplund, Martin; Liu, F.; Yong, David

doi:10.3847/1538-4357/aa6a1d

Cited by 47 publications

(33 citation statements)

References 53 publications

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“…Finally, we consider the possibility that the correlation between planet orbital period and stellar metallicity could be a byproduct of rocky planet ingestion by the star driven by inward migration (e.g., Meléndez et al 2009;Ramírez et al 2010Ramírez et al , 2014Schuler et al 2015;Mack et al 2014;Liu et al 2014;Teske et al 2015Teske et al , 2016aBedell et al 2017). For example, Mack et al (2014) compared the elemental abundances of the twin stars in the planet-hosting wide binary system HD 20782/81.…”

Section: Possible Mechanismsmentioning

confidence: 99%

Elemental Abundances of Kepler Objects of Interest in APOGEE. I. Two Distinct Orbital Period Regimes Inferred from Host Star Iron Abundances

Wilson¹,

Teske²,

Majewski³

et al. 2018

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The Apache Point Observatory Galactic Evolution Experiment (APOGEE) has observed ∼600 transiting exoplanets and exoplanet candidates from Kepler (Kepler Objects of Interest, KOIs), most with 18 epochs. The combined multi-epoch spectra are of high signal-to-noise ratio (typically 100) and yield precise stellar parameters and chemical abundances. We first confirm the ability of the APOGEE abundance pipeline, ASPCAP, to derive reliable [Fe/H] and effective temperatures for FGK dwarf stars-the primary Kepler host stellar type-by comparing the ASPCAP-derived stellar parameters with those from independent high-resolution spectroscopic characterizations for 221 dwarf stars in the literature. With a sample of 282 close-in ( < P 100 days) KOIs observed in the APOGEE KOI goal program, we find a correlation between orbital period and host star [Fe/H] characterized by a critical period, = -+ P 8.3 crit 4.1 0.1 days, below which small exoplanets orbit statistically more metalenriched host stars. This effect may trace a metallicity dependence of the protoplanetary disk inner radius at the time of planet formation or may be a result of rocky planet ingestion driven by inward planetary migration. We also consider that this may trace a metallicity dependence of the dust sublimation radius, but we find no statistically significant correlation with host T eff and orbital period to support such a claim.

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Section: Possible Mechanismsmentioning

confidence: 99%

Elemental Abundances of Kepler Objects of Interest in APOGEE. I. Two Distinct Orbital Period Regimes Inferred from Host Star Iron Abundances

Wilson¹,

Teske²,

Majewski³

et al. 2018

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“…Five of the six planets transit their star, but the secondoutermost planet was discovered with the radial velocity technique (Buchhave et al 2016). Kepler-11's and Kepler-20's stellar ages have been estimated at 3.2±0.9 Gyr (Bedell et al 2017) and 7.6±3.7 Gyr (Buchhave et al 2016), respectively, indicating that each system is long-term stable (see also Migaszewski et al 2012;Mahajan & Wu 2014;Hands et al 2014;Mia & Kushvah 2016;Jontof-Hutter et al 2017).…”

Section: Introductionmentioning

confidence: 99%

The origins of nearly coplanar, non-resonant systems of close-in super-Earths

Esteves

Izidoro

Raymond

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Some systems of close-in “super-Earths” contain five or more planets on non-resonant but compact and nearly coplanar orbits. The Kepler-11 system is an iconic representative of this class of system. It is challenging to explain their origins given that planet-disk interactions are thought to be essential to maintain such a high degree of coplanarity, yet these same interactions invariably cause planets to migrate into chains of mean motion resonances. Here we mine a large dataset of dynamical simulations of super-Earth formation by migration. These simulations match the observed period ratio distribution as long as the vast majority of planet pairs in resonance become dynamically unstable. When instabilities take place resonances are broken during a late phase of giant impacts, and typical surviving systems have planet pairs with significant mutual orbital inclinations. However, a subset of our unstable simulations matches the Kepler-11 system in terms of coplanarity, compactness, planet-multiplicity and non-resonant state. This subset have dynamical instability phases typically much shorter than ordinary systems. Unstable systems may keep a high degree of coplanarity post-instability if planets collide at very low orbital inclinations (≲ 1○) or if collisions promote efficient damping of orbital inclinations. If planetary scattering during the instability takes place at low orbital inclinations (i ≲ 1○), orbital inclinations are barely increased by encounters before planets collide.When planetary scattering pumps orbital inclinations to higher values (≳ 1○) planets tend to collide at higher mutual orbital inclinations, but depending on the geometry of collisions mergers’ orbital inclinations may be efficiently damped. Each of these formation pathways can produce analogues to the Kepler-11 system.

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“…K2-95 b: the radial velocity observations only placed an upper limit on the planetary mass(Pepper et al 2017). Kepler-11 g: the planetary mass is only constrained by upper bounds(Lissauer et al 2013;Bedell et al 2017).…”

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confidence: 99%

Beyond the exoplanet mass-radius relation

Ulmer-Moll

Santos

Figueira

et al. 2019

A&A

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Context. Mass and radius are two fundamental properties for characterising exoplanets, but only for a relatively small fraction of exoplanets are they both available. Mass is often derived from radial velocity measurements, while the radius is almost always measured using the transit method. For a large number of exoplanets, either the radius or the mass is unknown, while the host star has been characterised. Several mass-radius relations that are dependent on the planet's type have been published that often allow us to predict the radius. The same is true for a bayesian code, which forecasts the radius of an exoplanet given the mass or vice versa. Aims. Our goal is to derive the radius of exoplanets using only observables extracted from spectra used primarily to determine radial velocities and spectral parameters. Our objective is to obtain a mass-radius relation independent of the planet's type. Methods. We worked with a database of confirmed exoplanets with known radii and masses, as well as the planets from our Solar System. Using random forests, a machine learning algorithm, we computed the radius of exoplanets and compared the results to the published radii. Our code, Bem, is available online. In addition, we explored how the radius estimates compare to previously published mass-radius relations. Results. The estimated radii reproduces the spread in radius found for high mass planets better than previous mass-radius relations. The average radius error is 1.8 R ⊕ across the whole range of radii from 1-22 R ⊕ . We find that a random forest algorithm is able to derive reliable radii, especially for planets between 4 R ⊕ and 20 R ⊕ for which the error is under 25%. The algorithm has a low bias yet a high variance, which could be reduced by limiting the growth of the forest, or adding more data. Conclusions. The random forest algorithm is a promising method for deriving exoplanet properties. We show that the exoplanet's mass and equilibrium temperature are the relevant properties that constrain the radius, and do so with higher accuracy than the previous methods.

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Kepler-11 is a Solar Twin: Revising the Masses and Radii of Benchmark Planets via Precise Stellar Characterization

Cited by 47 publications

References 53 publications

Elemental Abundances of Kepler Objects of Interest in APOGEE. I. Two Distinct Orbital Period Regimes Inferred from Host Star Iron Abundances

Elemental Abundances of Kepler Objects of Interest in APOGEE. I. Two Distinct Orbital Period Regimes Inferred from Host Star Iron Abundances

The origins of nearly coplanar, non-resonant systems of close-in super-Earths

Beyond the exoplanet mass-radius relation

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