Constraints on the exosphere of CoRoT-7b

Guenther, E. W.; Cabrera, J.; Erikson, A.; Fridlund, M.; Lämmer, H.; Mura, A.; Rauer, H.; Schneider, Jean; Tulej, Marek; Paris, Philip von; Würz, Peter

doi:10.1051/0004-6361/201014868

Cited by 29 publications

(27 citation statements)

References 29 publications

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“…This may explain the lack of detection of exospheric Na and Ca by Guenther et al (2011). However, these calculations are first-order approximations and should be taken with a grain of salt.…”

Section: Hot Super-earthsmentioning

confidence: 99%

Vaporization of the Earth: Application to Exoplanet Atmospheres

Schaefer

Lodders

Fegley

2012

ApJ

152

186

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Currently, there are about 3 dozen known super-Earth (M < 10 M ⊕ ), of which 8 are transiting planets suitable for atmospheric follow-up observations. Some of the planets are exposed to extreme temperatures as they orbit close to their host stars, e.g., CoRot-7b, and all of these planets have equilibrium temperatures significantly hotter than the Earth.Such planets can develop atmospheres through (partial) vaporization of their crustal and/or mantle silicates. We investigated the chemical equilibrium composition of such heated systems from 500 -4000 K and total pressures from 10 -6 to 10 +2 bars. The major gases are H 2 O and CO 2 over broad temperature and pressure ranges, and Na, K, O 2 , SiO, and O at high temperatures and low pressures. We discuss the differences in atmospheric composition arising from vaporization of SiO 2 -rich (i.e., felsic) silicates (like Earth's continental crust) and MgO-, FeO-rich (i.e., mafic) silicates like the bulk silicate Earth.The computational results will be useful in planning spectroscopic studies of the atmospheres of Earth-like exoplanets.

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Section: Hot Super-earthsmentioning

confidence: 99%

Vaporization of the Earth: Application to Exoplanet Atmospheres

Schaefer

Lodders

Fegley

2012

ApJ

152

186

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“…Depending on the atmospheric molecular composition, this tail can be observable. Constraints on the molecules present in the atmosphere of exoplanets have already been inferred from observations with the VLT (Guenther et al 2011). …”

Section: Day Durationmentioning

confidence: 99%

Constraining physics of very hot super-Earths with theJames WebbTelescope. The case of CoRot-7b

Samuel¹,

Leconte²,

Rouan³

et al. 2014

A&A

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Context. Transit detection from space using ultra-precise photometry led to the first detection of super-Earths with solid surfaces: CoRot-7b and Kepler-10b. Because they lie only a few stellar radii from their host stars, these two rocky planets are expected to be extremely hot. Aims. Assuming that these planets are in a synchronous rotation state and receive strong stellar winds and fluxes, previous studies have suggested that they must be atmosphere-free and that a lava ocean is present on their hot dayside. In this article, we use several dedicated thermal models of the irradiated planet to study how observations with NIRSPEC on the James Webb Space Telescope (JWST) could further confirm and constrain, or reject the atmosphere-free lava ocean planet model for very hot super-Earths. Methods. Using CoRoT-7b as a working case, we explore the consequences on the phase-curve of a non tidal-locked rotation, with the presence/absence of an atmosphere, and for different values of the surface albedo. We then simulate future observations of the reflected light and thermal emission from CoRoT-7b with NIRSPEC-JWST and look for detectable signatures, such as time lag, of those peculiarities. We also study the possibility to retrieve the latitudinal surface temperature distribution from the observed SED. Results. We demonstrate that we should be able to constrain several parameters after observations of two orbits (42 h) thanks to the broad range of wavelengths accessible with JWST: i) the Bond albedo is retrieved to within ±0.03 in most cases. ii) The lag effect allows us to retrieve the rotation period within 3 h of a non phase-locked planet, whose rotation would be half the orbital period; for longer period, the accuracy is reduced. iii) Any spin period shorter than a limit in the range 30-800 h, depending on the thickness of the thermal layer in the soil, would be detected. iv) The presence of a thick gray atmosphere with a pressure of one bar, and a specific opacity higher than 10 −5 m −2 kg −1 is detectable. v) With spectra up to 4.5 μm, the latitudinal temperature profile can be retrieved to within 30 K with a risk of a totally wrong solution in 5% of the cases. This last result is obtained for a signal-to-noise ratio around 5 per resel, which should be reached on Corot-7 after a total exposure time of ∼70 h with NIRSPEC and only three hours on a V = 8 star. Conclusions. We conclude that it should thus be possible to distinguish the reference situation of a lava ocean with phase-locking and no atmosphere from other cases. In addition, obtaining the surface temperature map and the albedo brings important constraints on the nature or the physical state of the soil of hot super-Earths.

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“…Gliese 581d (Udry et al, 2007;Mayor et al, 2009) is the first SE to be found that may orbit in the HZ of its M dwarf star. Recently, initial constraints on the composition of hot transiting SEs such as CoRoT-7b (e.g., Guenther et al, 2011) and GJ1214b (e.g., Bean et al, 2011;Croll et al, 2011) have been discussed. Kepler 22b (Borucki et al, 2012) is the first transiting object found to occur in the HZ of a Sun-type star, several Earth-sized objects have been found orbiting a cool M dwarf (e.g., Muirhead et al, 2012), and detection of further SEs in the HZ is just beginning (e.g., Bonfils et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Potential Biosignatures in Super-Earth Atmospheres II. Photochemical Responses

et al. 2013

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Spectral characterization of super-Earth atmospheres for planets orbiting in the habitable zone of M dwarf stars is a key focus in exoplanet science. A central challenge is to understand and predict the expected spectral signals of atmospheric biosignatures (species associated with life). Our work applies a global-mean radiative-convectivephotochemical column model assuming a planet with an Earth-like biomass and planetary development. We investigated planets with gravities of 1g and 3g and a surface pressure of 1 bar around central stars with spectral classes from M0 to M7. The spectral signals of the calculated planetary scenarios have been presented by in an earlier work by Rauer and colleagues. The main motivation of the present work is to perform a deeper analysis of the chemical processes in the planetary atmospheres. We apply a diagnostic tool, the Pathway Analysis Program, to shed light on the photochemical pathways that form and destroy biosignature species. Ozone is a potential biosignature for complex life. An important result of our analysis is a shift in the ozone photochemistry from mainly Chapman production (which dominates in Earth's stratosphere) to smog-dominated ozone production for planets in the habitable zone of cooler (M5-M7)-class dwarf stars. This result is associated with a lower energy flux in the UVB wavelength range from the central star, hence slower planetary atmospheric photolysis of molecular oxygen, which slows the Chapman ozone production. This is important for future atmospheric characterization missions because it provides an indication of different chemical environments that can lead to very different responses of ozone, for example, cosmic rays. Nitrous oxide, a biosignature for simple bacterial life, is favored for low stratospheric UV conditions, that is, on planets orbiting cooler stars. Transport of this species from its surface source to the stratosphere where it is destroyed can also be a key process. Comparing 1g with 3g scenarios, our analysis suggests it is important to include the effects of interactive chemistry.

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Constraints on the exosphere of CoRoT-7b

Cited by 29 publications

References 29 publications

Vaporization of the Earth: Application to Exoplanet Atmospheres

Vaporization of the Earth: Application to Exoplanet Atmospheres

Constraining physics of very hot super-Earths with theJames WebbTelescope. The case of CoRot-7b

Potential Biosignatures in Super-Earth Atmospheres II. Photochemical Responses

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