LAMOST telescope reveals that Neptunian cousins of hot Jupiters are mostly single offspring of stars that are rich in heavy elements

Dong, Subo; Xie, Jijia; Zhou, Jingjing; Zheng, Zheng; Luo, A-Li

doi:10.1073/pnas.1711406115

Cited by 83 publications

(93 citation statements)

References 60 publications

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“…This is consistent with trends observed by Mulders et al (2016) and Dong et al (2018), who studied the host star metallicities for samples of 665 and 295 planets, respectively. Both studies used spectroscopically constrained metallicities from LAMOST.…”

Section: Metallicity and The Prevalence Of Short-period Planetssupporting

confidence: 91%

“…Mulders et al (2016) analyzed the LAMOST metallicities and a sample of 665 planet candidates, and found that the occurrence rate of hot small planets (P<10 days, R P < 4 R Å ) is three times higher among super-solar metallicity hosts compared to sub-solar hosts. Dong et al (2018) also analyzed LAMOST metallicities and a sample of 295 planets and reported a similar trend, also noting that hot Neptune-size planets are typically single.…”

Section: Introductionmentioning

confidence: 69%

“…Hot planets of intermediate sizes are very rare. This triangular "Hot Planet Desert" has been noted by Mazeh et al (2016) and Dong et al (2018), and is thought to be due to photo-evaporative envelope stripping.…”

Section: Planet Occurrence: Period and Radiusmentioning

confidence: 80%

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The California-Kepler Survey. IV. Metal-rich Stars Host a Greater Diversity of Planets

et al. 2018

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Probing the connection between a star's metallicity and the presence and properties of any associated planets offers an observational link between conditions during the epoch of planet formation and mature planetary systems. We explore this connection by analyzing the metallicities of Kepler target stars and the subset of stars found to host transiting planets. After correcting for survey incompleteness, we measure planet occurrence: the number of planets per 100 stars with a given metallicity M. Planet occurrence correlates with metallicity for some, but not all, planet sizes and orbital periods. For warm super-Earths having P=10-100days and R P =1.0-1.7R Å , planet occurrence is nearly constant over metallicities spanning −0.4 to +0.4dex. We find 20 warm super-Earths per 100 stars, regardless of metallicity. In contrast, the occurrence of warm sub-Neptunes (R P = 1.7-4.0 R Å ) doubles over that same metallicity interval, from 20 to 40 planets per 100 stars. We model the distribution of planets as, where β characterizes the strength of any metallicity correlation. This correlation steepens with decreasing orbital period and increasing planet size. + -+ . High metallicities in protoplanetary disks may increase the mass of the largest rocky cores or the speed at which they are assembled, enhancing the production of planets larger than 1.7R Å . The association between high metallicity and short-period planets may reflect disk density profiles that facilitate the inward migration of solids or higher rates of planet-planet scattering.

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Section: Metallicity and The Prevalence Of Short-period Planetssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 69%

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The California-Kepler Survey. IV. Metal-rich Stars Host a Greater Diversity of Planets

et al. 2018

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“…New observations provide us with the opportunity to characterize the super-Earth and sub-Neptune populations as a function of their host star properties (e.g., Petigura et al 2018;Dong et al 2018). This opens new avenues to investigate and contrast possible signatures the core-powered mass-loss mechanism and photoevaporation imprint on the exoplanet population (e.g., Owen & Murray-Clay 2018;Wu 2019).…”

Section: Introductionmentioning

confidence: 99%

Signatures of the core-powered mass-loss mechanism in the exoplanet population: dependence on stellar properties and observational predictions

Gupta

Schlichting

2020

Monthly Notices of the Royal Astronomical Society

159

102

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Recent studies have shown that atmospheric mass-loss powered by the cooling luminosity of a planet's core can explain the observed radius valley separating super-Earths and sub-Neptunes, even without photoevaporation. In this work, we investigate the dependence of this core-powered mass-loss mechanism on stellar mass (M * ), metallicity (Z * ) and age (τ * ). Without making any changes to the underlying planet population, we find that the core-powered mass-loss model yields a shift in the radius valley to larger planet sizes around more massive stars with a slope given by d logR p /d logM * 0.35, in agreement with observations. To first order, this slope is driven by the dependence of core-powered mass-loss on the bolometric luminosity of the host star and is given by d logR p /d logM * (3α − 2)/36 0.36, where (L * /L ) = (M * /M ) α is the stellar mass-luminosity relation and α 5 for the CKS dataset. We therefore find, contrary to photoevaporation models, no evidence for a correlation between planet and stellar mass. In addition, we show that the location of the radius valley is, to first order, independent of stellar age and metallicity. In contrast, assuming that the atmospheric opacity scales linearly with stellar metallicity, we determine that that the size of sub-Neptune population increases with metallicity and decreases with age with a slope given by d logR p /d logZ * 0.1 and d logR p /d logτ * −0.1, respectively. This implies that the abundance of super-Earths relative to sub-Neptunes increases with age but decreases with stellar metallicity. We conclude with a series of observational tests that can differentiate between core-powered mass-loss and photoevaporation models.

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“…Some planets may be much more massive, with high molecular-weight envelopes that resist escape to space. They could be the result of catastrophic escape of the H-He envelopes of close-in giant planets ("hot Jupiters") that have shrunk to Neptune size (Dong et al 2018). The mass of these planets can be measured by precision radial velocity measurements (e.g., Espinoza et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Zodiacal exoplanets in time – X. The orbit and atmosphere of the young ‘neptune desert’-dwelling planet K2-100b

Gaidos

Hirano

Mann

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We obtained high-resolution infrared spectroscopy and short-cadence photometry of the 600-800 Myr Praesepe star K2-100 during transits of its 1.67-day planet. This Neptune-size object, discovered by the NASA K2 mission, is an interloper in the "desert" of planets with similar radii on short period orbits. Our observations can be used to understand its origin and evolution by constraining the orbital eccentricity by transit fitting, measuring the spin-orbit obliquity by the Rossiter-McLaughlin effect, and detecting any extended, escaping hydrogen-helium envelope with the 10830Å line of neutral helium in the 2s 3 S triplet state. Transit photometry with 1-min cadence was obtained by the K2 satellite during Campaign 18 and transit spectra were obtained with the IRD spectrograph on the Subaru telescope. While the elevated activity of K2-100 prevented us from detecting the Rossiter-McLaughlin effect, the new photometry combined with revised stellar parameters allowed us to constrain the eccentricity to e < 0.15/0.28 with 90%/99% confidence. We modeled atmospheric escape as an isothermal, spherically symmetric Parker wind, with photochemistry driven by UV radiation that we estimate by combining the observed spectrum of the active Sun with calibrations from observations of K2-100 and similar young stars in the nearby Hyades cluster. Our non-detection (< 5.7mÅ) of a transit-associated He I line limits mass loss of a solar-composition atmosphere through a T ≤ 10000K wind to < 0.3 M ⊕ Gyr −1 . Either K2-100b is an exceptional desert-dwelling planet, or its mass loss is occurring at a lower rate over a longer interval, consistent with a core accretion-powered scenario for escape.

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LAMOST telescope reveals that Neptunian cousins of hot Jupiters are mostly single offspring of stars that are rich in heavy elements

Cited by 83 publications

References 60 publications

The California-Kepler Survey. IV. Metal-rich Stars Host a Greater Diversity of Planets

The California-Kepler Survey. IV. Metal-rich Stars Host a Greater Diversity of Planets

Signatures of the core-powered mass-loss mechanism in the exoplanet population: dependence on stellar properties and observational predictions

Zodiacal exoplanets in time – X. The orbit and atmosphere of the young ‘neptune desert’-dwelling planet K2-100b

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