Planets Across Space and Time (PAST). III. Morphology of the Planetary Radius Valley as a Function of Stellar Age and Metallicity in the Galactic Context Revealed by the LAMOST-Gaia-Kepler Sample

Chen, Di-Chang; Xie, Jijia; Zhou, Ji-Lin; Jun, Yang; Dong, Subo; Zheng, Zheng; Liu, Chao; Zong, Weikai; Luo, A-Li

doi:10.3847/1538-3881/ac641f

Cited by 17 publications

(9 citation statements)

References 63 publications

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“…Water worlds, on the other hand, will not significantly change in size after formation since their sizes are dominated by their ice-silicate composition and not H/He-dominated atmospheres. Indeed, this demographic analysis has been performed in the works of, e.g., Berger et al 2020b, Sandoval et al 2021, and Chen et al 2022 show that the radius gap evolves on ∼100 Myr to Gyr timescales. Moreover, a recent study from Fernandes et al (2022) calculated occurrence rates for a sample of exoplanets around young stars.…”

Section: Discussionmentioning

confidence: 99%

Conclusive Evidence for a Population of Water Worlds around M Dwarfs Remains Elusive

Rogers¹,

Schlichting²,

Owen

2023

ApJL

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The population of small, close-in exoplanets is bifurcated into super-Earths and sub-Neptunes. We calculate physically motivated mass–radius relations for sub-Neptunes, with rocky cores and H/He-dominated atmospheres, accounting for their thermal evolution, irradiation, and mass loss. For planets ≲10 M ⊕, we find that sub-Neptunes retain atmospheric mass fractions that scale with planet mass and show that the resulting mass–radius relations are degenerate with results for “water worlds” consisting of a 1:1 silicate-to-ice composition ratio. We further demonstrate that our derived mass–radius relation is in excellent agreement with the observed exoplanet population orbiting M dwarfs and that planet mass and radii alone are insufficient to determine the composition of some sub-Neptunes. Finally, we highlight that current exoplanet demographics show an increase in the ratio of super-Earths to sub-Neptunes with both stellar mass (and therefore luminosity) and age, which are both indicative of thermally driven atmospheric escape processes. Therefore, such processes should not be ignored when making compositional inferences in the mass–radius diagram.

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Section: Discussionmentioning

confidence: 99%

Conclusive Evidence for a Population of Water Worlds around M Dwarfs Remains Elusive

Rogers¹,

Schlichting²,

Owen

2023

ApJL

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“…The radius gap has also been found to have some reliance on various other system properties such as orbital period, incident flux (Cloutier & Menou 2020), and stellar parameters as well (Fulton & Petigura 2018;Berger et al 2020b;Chen et al 2022). This was recently explored by Petigura et al (2022) for the sample of 1246 planets in the CKS (Petigura et al 2017b), which was the Kepler-focused predecessor to the TESS-Keck Survey.…”

Section: Radius Gapmentioning

confidence: 99%

The TESS-Keck Survey. XV. Precise Properties of 108 TESS Planets and Their Host Stars

MacDougall

Petigura

Gilbert

et al. 2023

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We present the stellar and planetary properties for 85 TESS Objects of Interest (TOIs) hosting 108 planet candidates that compose the TESS-Keck Survey (TKS) sample. We combine photometry, high-resolution spectroscopy, and Gaia parallaxes to measure precise and accurate stellar properties. We then use these parameters as inputs to a light-curve processing pipeline to recover planetary signals and homogeneously fit their transit properties. Among these transit fits, we detect significant transit-timing variations among at least three multiplanet systems (TOI-1136, TOI-1246, TOI-1339) and at least one single-planet system (TOI-1279). We also reduce the uncertainties on planet-to-star radius ratios R p /R ⋆ across our sample, from a median fractional uncertainty of 8.8% among the original TOI Catalog values to 3.0% among our updated results. With this improvement, we are able to recover the Radius Gap among small TKS planets and find that the topology of the Radius Gap among our sample is broadly consistent with that measured among Kepler planets. The stellar and planetary properties presented here will facilitate follow-up investigations of both individual TOIs and broader trends in planet properties, system dynamics, and the evolution of planetary systems.

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“…We assumed solar metallicity for all systems. Metallicity does change stellar radius slightly, as well as possibly impacting the properties of sub-Neptunes above the radius gap (Chen et al 2022), but our spectra did not cover typical lines (e.g., Ca H and K or the Ca IR triplet) that can be used to measure metallicity at this spectral resolution; Lee et al 2008). In addition, we ran tests using model spectra of different metallicities and found that our results did not change significantly.…”

Section: Tablementioning

confidence: 85%

Revising Properties of Planet–Host Binary Systems. III. There Is No Observed Radius Gap for Kepler Planets in Binary Star Systems*

Sullivan

Kraus

Huber

et al. 2023

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Binary stars are ubiquitous; the majority of solar-type stars exist in binaries. Exoplanet occurrence rate is suppressed in binaries, but some multiples do still host planets. Binaries cause observational biases in planet parameters, with undetected multiplicity causing transiting planets to appear smaller than they truly are. We have analyzed the properties of a sample of 119 planet-host binary stars from the Kepler mission to study the underlying population of planets in binaries that fall in and around the radius valley, which is a demographic feature in period–radius space that marks the transition from predominantly rocky to predominantly gaseous planets. We found no statistically significant evidence for a radius gap for our sample of 122 planets in binaries when assuming that the primary stars are the planet hosts, with a low probability (p < 0.05) of the binary planet sample radius distribution being consistent with the single-star population of small planets via an Anderson–Darling test. These results reveal demographic differences in the planet size distribution between planets in binary and single stars for the first time, showing that stellar multiplicity may fundamentally alter the planet formation process. A larger sample and further assessment of circumprimary versus circumsecondary transits is needed to either validate this nondetection or explore other scenarios, such as a radius gap with a location that is dependent on binary separation.

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Planets Across Space and Time (PAST). III. Morphology of the Planetary Radius Valley as a Function of Stellar Age and Metallicity in the Galactic Context Revealed by the LAMOST-Gaia-Kepler Sample

Cited by 17 publications

References 63 publications

Conclusive Evidence for a Population of Water Worlds around M Dwarfs Remains Elusive

Conclusive Evidence for a Population of Water Worlds around M Dwarfs Remains Elusive

The TESS-Keck Survey. XV. Precise Properties of 108 TESS Planets and Their Host Stars

Revising Properties of Planet–Host Binary Systems. III. There Is No Observed Radius Gap for Kepler Planets in Binary Star Systems*

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