Atmosphere-Interior Exchange on Hot, Rocky Exoplanets

Kite, Edwin S.; Fegley, B.; Schaefer, Laura; Gaidos, Eric

doi:10.3847/0004-637x/828/2/80

Cited by 112 publications

(174 citation statements)

References 223 publications

(275 reference statements)

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“…The lava ocean scenario proposed by Léger et al (2011) for CoRoT-7b would have a Bond albedo less than 0.1 if made mostly of pure Al 2 O 3 , but Rouan et al (2011) propose that solid particles of ThO 2 floating in the lava ocean, depending on particle size, could produce an overall Bond albedo for the lava ocean of nearly 0.50, which could help to explain the unusual brightness of Kepler-10b. Also, Kite et al (2016) note that as the CaO/SiO 2 ratio increases, there seems to be a rise in reflectivity in the UV and visible. The data on this effect, however, are still very limited, but this could explain the higher albedo surfaces.…”

Section: Implications Of the Low Albedosmentioning

confidence: 93%

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Average Albedos of Close-in Super-Earths and Super-Neptunes from Statistical Analysis of Long-cadence Kepler Secondary Eclipse Data

Sheets

Deming

2017

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We present the results of our work to determine the average albedo for small, close-in planets in the Kepler candidate catalog. We have adapted our method of averaging short cadence light curves of multiple Kepler planet candidates to long cadence data, in order to detect an average albedo for the group of candidates. Long cadence data exist for many more candidates than the short cadence, and so we separate the candidates into smaller radius bins than in our previous work: 1-2 R ⊕ , 2-4 R ⊕ , and 4-6 R ⊕ . We find that on average, all three groups appear darker than suggested by the short cadence result, but not as dark as many hot Jupiters. The average geometric albedos for the three groups are 0.11 ± 0.06, 0.05 ± 0.04, and 0.11 ± 0.08, respectively, for the case where heat is uniformly distributed about the planet. If heat redistribution is inefficient, the albedos are even lower, since there will be a greater thermal contribution to the total light from the planet. We confirm that newly-identified false positive Kepler Object of Interest (KOI) 1662.01 is indeed an eclipsing binary at twice the period listed in the planet candidate catalog. We also newly identify planet candidate KOI 4351.01 as an eclipsing binary, and we report a secondary eclipse measurement for Kepler-4b (KOI 7.01) of ∼ 7.50 ppm at a phase of ∼ 0.7, indicating that the planet is on an eccentric orbit.

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Section: Implications Of the Low Albedosmentioning

confidence: 93%

“…Schaefer & Fegley 2009;Miguel et al 2011;Castan & Menou 2011;Kite et al 2016). We may in some cases be seeing bare surfaces.…”

Section: Implications Of the Low Albedosmentioning

confidence: 99%

Average Albedos of Close-in Super-Earths and Super-Neptunes from Statistical Analysis of Long-cadence Kepler Secondary Eclipse Data

Sheets

Deming

2017

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“…These studies hypothesize that phase curve properties are the result of either an optically thick atmosphere with heat recirculation confined to the planetary day-side, or a planet devoid of atmosphere, with low-viscosity magma flowing at the surface. However, Kite et al (2016) find, using basic models, that heat transport by magma currents is insufficient to explain the antistellar-hemisphere temperature found by Demory et al (2016b), and therefore an atmosphere is indicated.…”

Section: Cncementioning

confidence: 96%

“…However, follow-up secondary eclipse, phase-curve, and transit measurements (Demory et al , 2016a(Demory et al , 2016bRidden-Harper et al 2016;Tsiaras et al 2016), in conjunction with theoretical models (Lammer et al 2013;Ito et al 2015;Kite et al 2016), point to the existence of an envelope.…”

Section: Cncementioning

confidence: 99%

A Search for Water in a Super-Earth Atmosphere: High-resolution Optical Spectroscopy of 55Cancri e

Esteves

Mooij

Jayawardhana

et al. 2017

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We present the analysis of high-resolution optical spectra of four transits of 55Cnce, a low-density super-Earth that orbits a nearby Sun-like star in under 18 hr. The inferred bulk density of the planet implies a substantial envelope, which, according to mass-radius relationships, could be either a low-mass extended or a high-mass compact atmosphere. Our observations investigate the latter scenario, with water as the dominant species. We take advantage of the Doppler cross-correlation technique, high-spectral resolution, and the large wavelength coverage of our observations to search for the signature of thousands of optical water absorption lines. Using our observations with HDS on the Subaru telescope and ESPaDOnS on the Canada-France-Hawaii Telescope, we are able to place a 3σ lower limit of 10 g mol −1 on the mean-molecular weight of 55Cnce's water-rich (volume mixing ratio >10%), optically thin atmosphere, which corresponds to an atmospheric scale-height of ∼80 km. Our study marks the first high-spectral resolution search for water in a super-Earth atmosphere, and demonstrates that it is possible to recover known water-vapor absorption signals in a nearby super-Earth atmosphere, using highresolution transit spectroscopy with current ground-based instruments.

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“…It has been suggested that the implied heat transport on 55 Cnc e might be carried by the magma ocean. However, Kite et al (2016) argued that a magma ocean could not redistribute enough heat to affect a planet's measured phase curve. It is also conceivable that tidal heating could contribute to maintaining the night-side temperature.…”

Section: Introductionmentioning

confidence: 99%

Linking the Climate and Thermal Phase Curve of 55 Cancri e

Hammond

Pierrehumbert

2017

ApJ

106

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The thermal phase curve of 55 Cancri e is the first measurement of the temperature distribution of a tidally locked Super-Earth, but raises a number of puzzling questions about the planet's climate. The phase curve has a high amplitude and peak offset, suggesting that it has a significant eastward hot-spot shift as well as a large day-night temperature contrast. We use a general circulation model to model potential climates, and investigate the relation between bulk atmospheric composition and the magnitude of these seemingly contradictory features. We confirm theoretical models of tidally locked circulation are consistent with our numerical model of 55 Cnc e, and rule out certain atmospheric compositions based on their thermodynamic properties. Our best-fitting atmosphere has a significant hotspot shift and day-night contrast, although these are not as large as the observed phase curve. We discuss possible physical processes which could explain the observations, and show that night-side cloud formation from species such as SiO from a day-side magma ocean could potentially increase the phase curve amplitude and explain the observations. We conclude that the observations could be explained by an optically thick atmosphere with a low mean molecular weight, a surface pressure of several bar and a strong eastward circulation, with night-side cloud formation a possible explanation for the difference between our model and the observations.

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Atmosphere-Interior Exchange on Hot, Rocky Exoplanets

Cited by 112 publications

References 223 publications

Average Albedos of Close-in Super-Earths and Super-Neptunes from Statistical Analysis of Long-cadence Kepler Secondary Eclipse Data

Average Albedos of Close-in Super-Earths and Super-Neptunes from Statistical Analysis of Long-cadence Kepler Secondary Eclipse Data

A Search for Water in a Super-Earth Atmosphere: High-resolution Optical Spectroscopy of 55Cancri e

Linking the Climate and Thermal Phase Curve of 55 Cancri e

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