Exploring Kepler Giant Planets in the Habitable Zone

Hill, Michelle L.; Kane, Stephen R.; Duarte, Eduardo Seperuelo; Kopparapu, R.; Gelino, Dawn; Wittenmyer, Robert A.

doi:10.3847/1538-4357/aac384

Cited by 40 publications

(46 citation statements)

References 72 publications

(84 reference statements)

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“…The fact that Kepler-1704 b swings through its host star's habitable zone on its eccentric orbit is also potentially interesting from an exomoon standpoint (e.g., Heller 2012;Heller & Barnes 2013;Hill et al 2018). However, the plausibility of life developing on an exomoon that experiences such intense variation in stellar irradiation should be thoroughly scrutinized.…”

Section: Could Kepler-1704 B Host Exomoons?mentioning

confidence: 99%

Giant Outer Transiting Exoplanet Mass (GOT ‘EM) Survey. II. Discovery of a Failed Hot Jupiter on a 2.7 Yr, Highly Eccentric Orbit*

Dalba

Kane

et al. 2021

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Radial velocity (RV) surveys have discovered giant exoplanets on au-scale orbits with a broad distribution of eccentricities. Those with the most eccentric orbits are valuable laboratories for testing theories of high-eccentricity migration. However, few such exoplanets transit their host stars, thus removing the ability to apply constraints on formation from their bulk internal compositions. We report the discovery of Kepler-1704 b, a transiting 4.15 M J giant planet on a 988.88 day orbit with an extreme eccentricity of -+ 0.921 0.015 0.010 . Our decade-long RV baseline from the Keck I telescope allows us to measure the orbit and bulk heavy-element composition of Kepler-1704 b and place limits on the existence of undiscovered companions. A failed hot Jupiter, Kepler-1704 b was likely excited to high eccentricity by scattering events that possibly began during its gas accretion phase. Its final periastron distance was too large to allow for tidal circularization, so now it orbits its host from distances spanning 0.16-3.9 au. The maximum difference in planetary equilibrium temperature resulting from this elongated orbit is over 700 K. A simulation of the thermal phase curve of Kepler-1704 b during periastron passage demonstrates that it is a remarkable target for atmospheric characterization from the James Webb Space Telescope, which could potentially also measure the planet's rotational period as the hot spot from periastron rotates in and out of view. Continued characterization of the Kepler-1704 system promises to refine theories explaining the formation of hot Jupiters and cool giant planets like those in the solar system.

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Section: Could Kepler-1704 B Host Exomoons?mentioning

confidence: 99%

Giant Outer Transiting Exoplanet Mass (GOT ‘EM) Survey. II. Discovery of a Failed Hot Jupiter on a 2.7 Yr, Highly Eccentric Orbit*

Dalba

Kane

et al. 2021

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“…The boundaries of the HZ have been cataloged for a variety of known exoplanetary systems (Kane & Gelino 2012), including the candidate exoplanet systems discovered by the Kepler mission (Kane et al 2016;Hill et al 2018). The stellar distance plays a key role in determining the stellar properties that influence the HZ boundaries, highlighting the importance of accurate distance estimates (Johns et al 2018;Kane 2018).…”

Section: Stellar Mass Dependencementioning

confidence: 99%

Dynamical Packing in the Habitable Zone: The Case of Beta CVn

Kane

Turnbull

Fulton

et al. 2020

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Uncovering the occurrence rate of terrestrial planets within the habitable zone (HZ) of their host stars has been a particular focus of exoplanetary science in recent years. The statistics of these occurrence rates have largely been derived from transiting planet discoveries, and have uncovered numerous HZ planets in compact systems around M-dwarf host stars. Here we explore the width of the HZ as a function of spectral type, and the dynamical constraints on the number of stable orbits within the HZ for a given star. We show that, although the Hill radius for a given planetary mass increases with larger semimajor axis, the width of the HZ for earlier-type stars allows for more terrestrial planets in the HZ than late-type stars. In general, dynamical constraints allow ∼6 HZ Earth-mass planets for stellar masses 0.7M e , depending on the presence of farther out giant planets. As an example, we consider the case of Beta CVn, a nearby bright solar-type star. We present 20 yr of radial velocities (RV) from the Keck/High Resolution Echelle Spectrometer (HIRES) and Automated Planet Finder (APF) instruments and conduct an injection-recovery analysis of planetary signatures in the data. Our analysis of these RV data rule out planets more massive than Saturn within 10 au of the star. These system properties are used to calculate the potential dynamical packing of terrestrial planets in the HZ and show that such nearby stellar targets could be particularly lucrative for HZ planet detection by direct imaging exoplanet missions.

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“…It is possible that moons may provide the crucial ingredients for habitability. Using the fact that the gas giants of our solar system harbor several moons, Hill et al (2018) argues that the existence of gas giants within the HZ of 70 Kepler stars may provide evidence for a significant population of terrestrial moons in the HZ. Since the calculations within the current study only considers exoplanets, the discovery of a sizable number of exomoons could largely inflate the amount of habitability expected within each system.…”

Section: Discussionmentioning

confidence: 99%

Accounting for multiplicity in calculating eta Earth

Zink

Hansen

2019

Monthly Notices of the Royal Astronomical Society

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Using the updated exoplanet population parameters of our previous study, which includes the planetary radius updates from Gaia DR2 and an inferred multiplicity distribution, we provide a revised η ⊕ calculation. This is achieved by sampling planets from our derived population model and determining which planets meet our criterion for habitability. To ensure robust results, we provide probabilities calculated over a range of upper radius limits. Our most optimistic criterion for habitability provides an η ⊕ value of 0.34±0.02 planets star . We also consider the effects of multiplicity and the number of habitable planets each system may contain. Our calculation indicates that 6.4 ± 0.5% of GK dwarfs have more than one planet within their habitable zone. This optimistic habitability criterion also suggests that 0.036 ± 0.009% of solar-like stars will harbor 5 or more habitable planets. These tightly packed highly habitable system should be extremely rare, but still possible. Even with our most pessimistic criterion we still expect that 1.8 ± 0.2% of solar-like stars harbor more than one habitable planet.

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Exploring Kepler Giant Planets in the Habitable Zone

Cited by 40 publications

References 72 publications

Giant Outer Transiting Exoplanet Mass (GOT ‘EM) Survey. II. Discovery of a Failed Hot Jupiter on a 2.7 Yr, Highly Eccentric Orbit*

Giant Outer Transiting Exoplanet Mass (GOT ‘EM) Survey. II. Discovery of a Failed Hot Jupiter on a 2.7 Yr, Highly Eccentric Orbit*

Dynamical Packing in the Habitable Zone: The Case of Beta CVn

Accounting for multiplicity in calculating eta Earth

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