Theoretical Spectra of Terrestrial Exoplanet Surfaces

Hu, Renyu; Ehlmann, B. L.; Seager, Sara

doi:10.1088/0004-637x/752/1/7

Cited by 130 publications

(127 citation statements)

References 71 publications

Supporting

Mentioning

125

Contrasting

Order By: Relevance

“…I find similarly large albedos for a subset of the superEarths studied here. Still considering Kepler-10b, a wide range of solid surface compositions (Hu et al 2012) could match the observed excess of brightness temperature in the Kepler bandpass. Determining how mineral reflective properties evolve through molten phases with increasing temperature will be paramount to lift this degeneracy.…”

Section: Surfacesmentioning

confidence: 95%

THE ALBEDOS OF KEPLER' S CLOSE-IN SUPER-EARTHS

Demory

2014

ApJ

View full text Add to dashboard Cite

Exoplanet research focusing on the characterization of super-Earths is currently limited to those handful targets orbiting bright stars that are amenable to detailed study. This Letter proposes to look at alternative avenues to probe the surface and atmospheric properties of this category of planets, known to be ubiquitous in our galaxy. I conduct Markov Chain Monte Carlo lightcurve analyses for 97 Kepler close-in R P 2.0R ⊕ super-Earth candidates with the aim to detect their occultations at visible wavelengths. Brightness temperatures and geometric albedos in the Kepler bandpass are constrained for 27 super-Earth candidates. A hierarchical Bayesian modeling approach is then employed to characterize the population-level reflective properties of these close-in super-Earths. I find median geometric albedos A g in the Kepler bandpass ranging between 0.16 and 0.30, once decontaminated from thermal emission. These super-Earths geometric albedos are statistically larger than for hot Jupiters, which have medians A g ranging between 0.06 and 0.11. A subset of objects, including Kepler-10b, exhibit significantly larger albedos (A g 0.4). I argue that a better understanding of the incidence of stellar irradiation on planetary surface and atmospheric processes is key to explain the diversity in albedos observed for close-in super-Earths.

show abstract

Section: Surfacesmentioning

confidence: 95%

THE ALBEDOS OF KEPLER' S CLOSE-IN SUPER-EARTHS

Demory

2014

ApJ

View full text Add to dashboard Cite

show abstract

“…To avoid having too many free parameters, we consider CoRoT-7b as a prototype hot SE and carry on the analysis in this study case only. Furthermore, we focus on broadband photometry, so the composition of the rock (Hu et al 2012) or the observation of molecules in a cometary tail, which requires high spectral resolution, is not examined.…”

Section: Goalmentioning

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

View full text Add to dashboard Cite

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.

show abstract

“…Naturally, observations at multiple infrared wavelengths are also desirable to observe spectral features of different molecular species and/or surface compositions (e.g., Kuiper et al 1947;Hu et al 2012). Table 1 shows that the number of planets accessible to highcontrast characterization drops steadily as the observing wavelength increases from 1.0 µm to 3.5 µm.…”

Section: Observing Wavelength: Scattered Starlight and Thermal Emissionmentioning

confidence: 99%

“…All three GSMT projects have proposed AO-assisted MIR instruments (Brandl et al 2010;Tokunaga et al 2010;Okamoto et al 2010;Hinz et al 2012). The longer wavelengths at which these instruments would operate roughly correspond to the Wien peak of cool planets' blackbody emission, thereby providing a method to measure radiometric radii (Morrison 1973), the surface compositions of airless planets (Hu et al 2012), and the potential to detect exoplanetary ozone (e.g., Rugheimer et al 2012, and references therein).…”

Section: Observing Wavelength: Scattered Starlight and Thermal Emissionmentioning

confidence: 99%

On high-contrast characterization of nearby, short-period exoplanets with giant segmented-mirror telescopes

Crossfield

2013

A&A

View full text Add to dashboard Cite

Measurements of the frequency with which short-period planets occur around main sequence stars allows a direct prediction of the number and types of such planets that will be amenable to characterization by high-contrast instruments on future giant segmentedmirror telescopes (GSMTs). Adopting conservative assumptions, I predict of order 10 planets with radii R P = 1−8 R ⊕ and equilibrium temperatures 400 K should be accessible around stars within 8 pc of the Sun. These numbers are roughly the same for both nearinfrared observations of scattered starlight and mid-infrared observations of planetary thermal emission, with the latter observations demonstrating greater relative sensitivity to smaller and cooler planets. Adopting the conservative assumption that planets with R P = 1−2 R ⊕ and 2−4 R ⊕ occur with equal frequency, I predict a 40% chance that a planet with R P = 1−2 R ⊕ and equilibrium temperature 200-250 K will accessible to high-contrast thermal infrared characterization; this would be a compelling object for further study. To validate these predictions, more detailed analyses are needed of the occurrence frequencies of low-mass planets around M dwarfs, both in the Kepler field and in the solar neighborhood. Several planets already discovered by radial velocity surveys will be accessible to near-infrared high-contrast GSMT observations, including the low-mass planets α Cen Bb and (depending on their albedos) GJ 139c and d, GJ 876b and c, and τ Cet b, c, and d; τ Cet f would be amenable to thermal infrared characterization. Further efforts to model the near-infrared reflectance and mid-infrared emission of these and other short-period planets are clearly warranted, and will pave the way for the interpretation of future high-contrast characterization of a variety of planets around the nearest stars.

show abstract

Theoretical Spectra of Terrestrial Exoplanet Surfaces

Cited by 130 publications

References 71 publications

THE ALBEDOS OF KEPLER' S CLOSE-IN SUPER-EARTHS

THE ALBEDOS OF KEPLER' S CLOSE-IN SUPER-EARTHS

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

On high-contrast characterization of nearby, short-period exoplanets with giant segmented-mirror telescopes

Contact Info

Product

Resources

About