The Albedos of Kepler's Close-in super-Earths

Abstract

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 $R_P\lesssim 2.0R_{\oplus }$ 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\gtrsim$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.

arXiv commentApJ Letters, in press. 6 pages, 3 figures and 1 table

References in corpus (36)

• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• The false positive rate of Kepler and the occurrence of planets
• A super-Earth transiting a nearby low-mass star
• Transiting exoplanets from the CoRoT space mission VIII. CoRoT-7b: the first Super-Earth with measured radius
• KEPLER's First Rocky Planet: Kepler-10b
• Revised Stellar Properties of Kepler Targets for the Quarter 1-16 Transit Detection Run
• Kepler Eclipsing Binary Stars. II. 2165 Eclipsing Binaries in the Second Data Release
• The Statistics of Albedo and Heat Recirculation on Hot Exoplanets
• Initial Characteristics of Kepler Long Cadence Data For Detecting Transiting Planets
• Inference of Inhomogeneous Clouds in an Exoplanet Atmosphere
• A Super-Earth Transiting a Naked-Eye Star
• Three Possible Origins for the Gas Layer on GJ 1214b
• Lack of Inflated Radii for Kepler Giant Planet Candidates Receiving Modest Stellar Irradiation
• CHEOPS: A Transit Photometry Mission for ESA's Small Mission Programme
• Densities and Eccentricities of 139 Kepler Planets from Transit Time Variations
• Planetary Candidates Observed by Kepler IV: Planet Sample From Q1-Q8 (22 Months)
• HAT-P-7b: An Extremely Hot Massive Planet Transiting a Bright Star in the Kepler Field
• Chemistry of Silicate Atmospheres of Evaporating Super-Earths
• Detection of a transit of the super-Earth 55 Cnc e with Warm Spitzer
• Inferring the eccentricity distribution
• The TRAPPIST survey of southern transiting planets. I. Thirty eclipses of the ultra-short period planet WASP-43 b
• Transits and Occultations of an Earth-Sized Planet in an 8.5-Hour Orbit
• Understanding Trends Associated with Clouds in Irradiated Exoplanets
• Pre-Spectroscopic False Positive Elimination of Kepler Planet Candidates
• On the Absorption and Redistribution of Energy in Irradiated Planets
• The Nature of the Atmosphere of the Transiting Super-Earth GJ 1214b
• The thermal emission of the young and massive planet CoRoT-2b at 4.5 and 8 microns
• Theoretical Spectra of Terrestrial Exoplanet Surfaces
• Compositions of Hot Super-Earth Atmospheres: exploring Kepler Candidates
• Studying the atmosphere of the exoplanet HAT-P-7b via secondary eclipse measurements with EPOXI, Spitzer and Kepler
• Photometrically derived masses and radii of the planet and star in the TrES-2 system
• Atmosphere and Spectral Models of the Kepler-Field Planets HAT-P-7b and TrES-2
• The orbital phases and secondary transit of Kepler-10b - A physical interpretation based on the Lava-ocean planet model -
• Atmospheres of Hot Super-Earths
• On the Stability of Super-Earth Atmospheres
• Spectroscopic direct detection of reflected light from extra-solar planets

Cited by in corpus (42)

• Planetary Candidates Observed by Kepler. VII. The First Fully Uniform Catalog Based on The Entire 48 Month Dataset (Q1-Q17 DR24)
• Calibrating Gyrochronology using Kepler Asteroseismic targets
• Changing Phases of Alien Worlds: Probing Atmospheres of Kepler Planets with High-Precision Photometry
• Planetary Candidates Observed by Kepler V: Planet Sample from Q1-Q12 (36 Months)
• The California-Kepler Survey. II. Precise Physical Properties of 2025 Kepler Planets and Their Host Stars
• Predictions of the atmospheric composition of GJ 1132b
• Atmosphere-interior exchange on hot rocky exoplanets
• Aerosols in Exoplanet Atmospheres
• Advances in exoplanet science from Kepler
• Evidence for a spectroscopic direct detection of reflected light from 51 Peg b
• Investigating hot-Jupiter inflated radii with hierarchical Bayesian modelling
• K2 and Spitzer phase curves of the rocky ultra-short-period planet K2-141 b hint at a tenuous rock vapor atmosphere
• Three Super-Earths Orbiting HD 7924
• An Overabundance of Low-density Neptune-like Planets
• Laboratory spectra of hot molecules: data needs for hot super-Earth exoplanets
• Probing exoplanet clouds with optical phase curves
• The Eccentricity Distribution of Short-Period Planet Candidates Detected by Kepler in Occultation
• Super-Earths and Earth-like Exoplanets
• Low Albedo Surfaces of Lava Worlds
• The initial physical conditions of Kepler-36 b & c
• Searching for reflected light from $\tau$ Bootis b with high-resolution ground-based spectroscopy: Approaching the $10^{-5}$ contrast barrier
• Three Temperate Neptunes Orbiting Nearby Stars
• Evidence for Reflected Light from the Most Eccentric Exoplanet Known
• Statistical Eclipses of Close-in Kepler Sub-Saturns
• Multi-season optical modulation phased with the orbit of the super-Earth 55 Cnc e
• Role of magma oceans in controlling carbon and oxygen of sub-Neptune atmospheres
• K2-139 b: a low-mass warm Jupiter on a 29-day orbit transiting an active K0 V star
• Average Albedos of Close-in Super-Earths and Neptunes from Statistical Analysis of Long Cadence Kepler Secondary Eclipse Data
• The TESS-Keck Survey. XV. Precise Properties of 108 TESS Planets and Their Host Stars
• 55 Cancri e's occultation captured with CHEOPS
• Characterization of Exoplanets: Secondary Eclipses
• Kepler's Dark Worlds: a Low Albedo for an Ensemble of Neptunian and Terran Exoplanets
• How to Characterize the Atmosphere of a Transiting Exoplanet
• Exoplanet phase curves at large phase angles. Diagnostics for extended hazy atmospheres
• Probing Kepler's hottest small planets via homogeneous search and analysis of optical secondary eclipses and phase variations
• Two Planets Straddling the Habitable Zone of The Nearby K Dwarf Gl 414A
• WASP-104b is Darker than Charcoal
• Exploring Super-Earth Surfaces: Albedo of Near-Airless Magma Ocean Planets and Topography
• From Super-Earths to Mini-Neptunes: Implications of a Surface on Atmospheric Circulation
• Refraction in exoplanet atmospheres: Photometric signatures, implications for transmission spectroscopy, and search in Kepler data
• Reflected light from giant planets in habitable zones: Tapping into the power of the Cross-Correlation Function
• How does the shape of the stellar spectrum affect the Raman scattering features in the albedo of exoplanets?