A seven-planet resonant chain in TRAPPIST-1

Luger, Rodrigo; Sestovic, Marko; Kruse, Ethan; Grimm, Simon L.; Demory, Brice-Olivier; Agol, Eric; Bolmont, Émeline; Fabrycky, Daniel C.; Fernandes, Célia; Grootel, Valérie Van; Burgasser, Adam J.; Gillon, M.; Ingalls, James G.; Jehin, Emmanuël; Raymond, Sean N.; Selsis, F.; Triaud, A. H. M. J.; Barclay, Thomas; Barentsen, Geert; Howell, Steve B.; Delrez, Laetitia; Wit, Julien de; Foreman-Mackey, Daniel; Holdsworth, Daniel Luke; Leconte, Jérémy; Lederer, Susan M.; Turbet, Martin; Almleaky, Yaseen; Benkhaldoun, Z.; Magain, Pierre; Morris, Brett M.; Heng, Kevin; Queloz, D.

doi:10.1038/s41550-017-0129

Cited by 350 publications

(440 citation statements)

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“…Figure 9 shows the present-day orbital distances of the seven planets and the evolution of the HZ inner limits for a TRAPPIST-1 analog. Using the mass of TRAPPIST-1 ( M 0.0802  ) yielded an HZ inner edge much closer to what is shown in Gillon et al (2017), because low-mass star evolution models tend to underestimate the luminosity for active stars (Chabrier et al 2007) such as TRAPPIST-1 (Luger et al 2017;Vida et al 2017). We therefore revised the stellar mass for TRAPPIST-1 following the prescription of Chabrier et al (2007), by greatly reducing convection efficiency in CLES (Code Liégeois d'Évolution Stellaire) stellar evolution models (Scuflaire et al 2008).…”

Section: Evolution Of the Planets Under High-energy Irradiationmentioning

confidence: 99%

“…If TRAPPIST-1 is 3 Gyr old (the lower estimate of the age given in Luger et al 2017), planet b potentially lost more than 20EO H and planet c more than EO 10 H . If planets b and c formed with an Earth-like water content, they are likely dry today, whatever the assumptions on the XUV flux and the age of the star.…”

Section: Water Loss Evolutionmentioning

confidence: 99%

“…For instance, the albedo of ice and snow is significantly lower in the infrared (Joshi & Haberle 2012), which means that the temperature of a planet is higher around TRAPPIST-1 than around a solar-type star for a given flux, and therefore the inner edge of the HZ corresponds to a lower incoming flux. We estimated the age at which the planets entered the shrinking HZ ( Table 3), considering that their migration stopped when the gas disk dissipated (Luger et al 2017;Tamayo et al 2017). This age corresponds to the end of the runaway greenhouse phase, and we found it lasted between a few 10 Myr (for planet h) to a few 100 Myr (for planet d in the synchronized scenario).…”

Section: Evolution Of the Planets Under High-energy Irradiationmentioning

confidence: 99%

“…Masses for the TRAPPIST-1 planets , Table 1) were derived through transit-timing variations (TTV; Holman & Murray 2005). The seventh planet's properties were recently refined by Luger et al (2017), who showed that three-body resonances link every planet of this complex system. The combined mass and radius measurements for the TRAPPIST-1 planets are consistent with rocky, water-enriched bulk compositions, with TRAPPIST-1f having a density low enough to harbor up to 50% of water in its mass.…”

Section: Introductionmentioning

confidence: 99%

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Temporal Evolution of the High-energy Irradiation and Water Content of TRAPPIST-1 Exoplanets

Bourrier

Wit

Bolmont

et al. 2017

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The ultracool dwarf star TRAPPIST-1 hosts seven Earth-size transiting planets, some of which could harbor liquid water on their surfaces. Ultraviolet observations are essential to measuring their high-energy irradiation and searching for photodissociated water escaping from their putative atmospheres. Our new observations of the TRAPPIST-1 Lyα line during the transit of TRAPPIST-1c show an evolution of the star emission over three months, preventing us from assessing the presence of an extended hydrogen exosphere. Based on the current knowledge of the stellar irradiation, we investigated the likely history of water loss in the system. Planets b to d might still be in a runaway phase, and planets within the orbit of TRAPPIST-1g could have lost more than 20 Earth oceans after 8 Gyr of hydrodynamic escape. However, TRAPPIST-1e to h might have lost less than three Earth oceans if hydrodynamic escape stopped once they entered the habitable zone (HZ). We caution that these estimates remain limited by the large uncertainty on the planet masses. They likely represent upper limits on the actual water loss because our assumptions maximize the X-rays to ultraviolet-driven escape, while photodissociation in the upper atmospheres should be the limiting process. Late-stage outgassing could also have contributed significant amounts of water for the outer, more massive planets after they entered the HZ. While our results suggest that the outer planets are the best candidates to search for water with the JWST, they also highlight the need for theoretical studies and complementary observations in all wavelength domains to determine the nature of the TRAPPIST-1 planets and their potential habitability.

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Section: Evolution Of the Planets Under High-energy Irradiationmentioning

confidence: 99%

Section: Water Loss Evolutionmentioning

confidence: 99%

Section: Evolution Of the Planets Under High-energy Irradiationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Temporal Evolution of the High-energy Irradiation and Water Content of TRAPPIST-1 Exoplanets

Bourrier

Wit

Bolmont

et al. 2017

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131

133

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“…The luminosity of TRAPPIST-1 is 0.000524 L and the orbital period of TRAPPIST-1h is 18.8 days (Luger et al 2017). The distance with an equivalent incident flux around the Sun would correspond to a period of 1677 days.…”

Section: Red Dwarf Host Starmentioning

confidence: 99%

Refraction in exoplanet atmospheres

Alp

Demory

2018

A&A

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Context. Refraction deflects photons that pass through atmospheres, which affects transit light curves. Refraction thus provides an avenue to probe physical properties of exoplanet atmospheres and to constrain the presence of clouds and hazes. In addition, an effective surface can be imposed by refraction, thereby limiting the pressure levels probed by transmission spectroscopy. Aims. The main objective of the paper is to model the effects of refraction on photometric light curves for realistic planets and to explore the dependencies on atmospheric physical parameters. We also explore under which circumstances transmission spectra are significantly affected by refraction. Finally, we search for refraction signatures in photometric residuals in Kepler data. Methods. We use the model of Hui & Seager (2002) to compute deflection angles and refraction transit light curves, allowing us to explore the parameter space of atmospheric properties. The observational search is performed by stacking large samples of transit light curves from Kepler. Results. We find that out-of-transit refraction shoulders are the most easily observable features, which can reach peak amplitudes of ∼10 parts per million (ppm) for planets around Sun-like stars. More typical amplitudes are a few ppm or less for Jovians and at the sub-ppm level for super-Earths. In-transit, ingress, and egress refraction features are challenging to detect because of the short timescales and degeneracies with other transit model parameters. Interestingly, the signal-to-noise ratio of any refraction residuals for planets orbiting Sun-like hosts are expected to be similar for planets orbiting red dwarfs. We also find that the maximum depth probed by transmission spectroscopy is not limited by refraction for weakly lensing planets, but that the incidence of refraction can vary significantly for strongly lensing planets. We find no signs of refraction features in the stacked Kepler light curves, which is in agreement with our model predictions.

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Host Star Driven Exoplanet Mass Loss and Possible Surface Water

Linsky

2019

Lecture Notes in Physics

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A seven-planet resonant chain in TRAPPIST-1

Cited by 350 publications

References 60 publications

Temporal Evolution of the High-energy Irradiation and Water Content of TRAPPIST-1 Exoplanets

Temporal Evolution of the High-energy Irradiation and Water Content of TRAPPIST-1 Exoplanets

Refraction in exoplanet atmospheres

Host Star Driven Exoplanet Mass Loss and Possible Surface Water

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