Linking the Climate and Thermal Phase Curve of 55 Cancri e

Hammond, Mark; Pierrehumbert, Raymond T.

doi:10.3847/1538-4357/aa9328

Cited by 108 publications

(79 citation statements)

References 44 publications

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“…Such high surface pressures are at odds with the maximum surface pressure of ∼0.1 bar estimated by Ito et al (2015) for a mineral atmosphere in equilibrium with molten rock. The uncertainties we derive for the gas layer thicknesses and mean molecular weights do not allow us to distinguish between a mineral atmosphere and a gas layer dominated by molecules such as CO or N 2 , as suggested by the infrared phase curve of 55 Cnc (Angelo & Hu 2017;Hammond & Pierrehumbert 2017).…”

Section: Disentangling Between a Dry And Wet 55 Cnc Ementioning

confidence: 87%

The 55 Cancri system reassessed

Bourrier

Dumusque

Dorn

et al. 2018

A&A

106

130

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Orbiting a bright, nearby star the 55 Cnc system offers a rare opportunity to study a multiplanet system that has a wide range of planetary masses and orbital distances. Using two decades of photometry and spectroscopy data, we have measured the rotation of the host star and its solar-like magnetic cycle. Accounting for this cycle in our velocimetric analysis of the system allows us to revise the properties of the outermost giant planet and its four planetary companions. The innermost planet 55 Cnc e is an unusually close-in super-Earth, whose transits have allowed for detailed follow-up studies. Recent observations favor the presence of a substantial atmosphere yet its composition, and the nature of the planet, remain unknown. We combined our derived planet mass (M p = 8.0±0.3 M Earth ) with refined measurement of its optical radius derived from HST/STIS observations (R p = 1.88±0.03 R Earth over 530-750 nm) to revise the density of 55 Cnc e (ρ = 6.7±0.4 g cm −3 ). Based on these revised properties we have characterized possible interiors of 55 Cnc e using a generalized Bayesian model. We confirm that the planet is likely surrounded by a heavyweight atmosphere, contributing a few percents of the planet radius. While we cannot exclude the presence of a water layer underneath the atmosphere, this scenario is unlikely given the observations of the planet across the entire spectrum and its strong irradiation. Follow-up observations of the system in photometry and in spectroscopy over different time-scales are needed to further investigate the nature and origin of this iconic super-Earth.

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Section: Disentangling Between a Dry And Wet 55 Cnc Ementioning

confidence: 87%

The 55 Cancri system reassessed

Bourrier

Dumusque

Dorn

et al. 2018

A&A

106

130

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“…We draw specific attention to the difference between "evolutionary" and "permanent" magma ocean which is studied in other works (e.g. Hammond & Pierrehumbert 2017). Both the transient and continuous magma ocean that we study belong to the so called "evolutionary" magma oceans generated during the accretional process.…”

Section: Evolutionary and Permanent Magma Oceansmentioning

confidence: 98%

“…We suggest the auxiliary/complementary use of observations obtained from the permanent magma ocean type, such as potentially on 55 Cancri e (Demory et al 2016;Angelo & Hu 2017) and Kepler 78b. From there one could isolate characteristic atmospheric signatures such as: the atmospheric effects of evaporated silicate species that develop over the molten rocky surface (Fegley et al 2016;Kite et al 2016;Hammond & Pierrehumbert 2017) and the oxides in the presence of a steam atmosphere (Fegley et al 2016). Detecting similar silicate cloud signatures on planets close to the continuous MO compositional distinction that is observed at low vapor pressures (4 bar) would serve as a proxy of their composition (T RF,0 ) and of their water content.…”

Section: Magma Oceans On Other Planetsmentioning

confidence: 99%

What Factors Affect the Duration and Outgassing of the Terrestrial Magma Ocean?

Nikolaou

Katyal

Tosi

et al. 2019

ApJ

141

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The magma ocean (MO) is a crucial stage in the build-up of terrestrial planets. Its solidification and the accompanying outgassing of volatiles set the conditions for important processes occurring later or even simultaneously, such as solid-state mantle convection and atmospheric escape. To constrain the duration of a global-scale Earth MO we have built and applied a 1D interior model coupled alternatively with a grey H 2 O/CO 2 atmosphere or with a pure H 2 O atmosphere treated with a line-by-line model described in a companion paper by Katyal et al. (2019). We study in detail the effects of several factors affecting the MO lifetime, such as the initial abundance of H 2 O and CO 2 , the convection regime, the viscosity, the mantle melting temperature, and the longwave radiation absorption from the atmosphere. In this specifically multi-variable system we assess the impact of each factor with respect to a reference setting commonly assumed in the literature. We find that the MO stage can last from a few thousand to several million years. By coupling the interior model with the line-by-line atmosphere model, we identify the conditions that determine whether the planet experiences a transient magma ocean or it ceases to cool and maintains a continuous magma ocean. We find a dependence of this distinction simultaneously on the mass of the outgassed H 2 O atmosphere and on the MO surface melting temperature. We discuss their combined impact on the MO's lifetime in addition to the known dependence on albedo, orbital distance and stellar luminosity and we note observational degeneracies that arise thereby for target exoplanets.

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“…Phase curve observations of 55 Cnc e by Demory et al (2016b) show a significant hot-spot shift which presents a case for a substantial atmosphere. Follow up analysis of the same phase curve data by Kite et al (2016); Angelo & Hu (2017) and GCM modelling by Hammond & Pierrehumbert (2017) also strongly imply that the seen effectiveness of the advective heat redistribution on the planet cannot be explained solely via the surface lava currents, instead suggesting that an optically thick atmosphere is needed.…”

Section: Introductionmentioning

confidence: 79%

“…Despite observational and modeling efforts (Demory et al 2016b;Angelo & Hu 2017;Hammond & Pierrehumbert 2017;Bourrier et al 2018;Miguel 2019), 55 Cnc e remains one of the most mysterious worlds discovered to date. Its large day-night temperature gradient and an eastwards shifted hot spot favours a scenario where it is surrounded by a high-mean-molecular weight atmosphere, possibly composed mainly of N 2 .…”

Section: Resultsmentioning

confidence: 99%

Atmospheric compositions and observability of nitrogen-dominated ultra-short-period super-Earths

Zilinskas

Miguel

Mollière

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We explore the chemistry and observability of nitrogen dominated atmospheres for ultra-short-period super-Earths. We base the assumption, that super-Earths could have nitrogen filled atmospheres, on observations of 55 Cnc e that favour a scenario with a high-mean-molecular-weight atmosphere. We take Titan's elemental budget as our starting point and using chemical kinetics compute a large range of possible compositions for a hot super-Earth. We use analytical temperature profiles and explore a parameter space spanning orders of magnitude in C/O & N/O ratios, while always keeping nitrogen the dominant component. We generate synthetic transmission and emission spectra and assess their potential observability with the future James Webb Space Telescope and ARIEL. Our results suggest that HCN is a strong indicator of a high C/O ratio, which is similar to what is found for H-dominated atmospheres. We find that these worlds are likely to possess C/O > 1.0, and that HCN, CN, CO should be the primary molecules to be searched for in thermal emission. For lower temperatures (T < 1500 K), we additionally find NH 3 in high N/O ratio cases, and C 2 H 4 , CH 4 in low N/O ratio cases to be strong absorbers. Depletion of hydrogen in such atmospheres would make CN, CO and NO exceptionally prominent molecules to look for in the 0.6 -5.0 µm range. Our models show that the upcoming JWST and ARIEL missions will be able to distinguish atmospheric compositions of ultra-short period super-Earths with unprecedented confidence.

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Linking the Climate and Thermal Phase Curve of 55 Cancri e

Cited by 108 publications

References 44 publications

The 55 Cancri system reassessed

The 55 Cancri system reassessed

What Factors Affect the Duration and Outgassing of the Terrestrial Magma Ocean?

Atmospheric compositions and observability of nitrogen-dominated ultra-short-period super-Earths

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