Transmission spectroscopy for the warm sub-Neptune HD3167c: evidence for molecular absorption and a possible high metallicity atmosphere

Abstract

We present a transmission spectrum for the warm (500-600K) sub-Neptune HD3167c obtained using the Hubble Space Telescope Wide Field Camera 3 infrared spectrograph. We combine these data, which span the 1.125-1.643 micron wavelength range, with broadband transit measurements made using Kepler/K2 (0.6-0.9 micron) and Spitzer/IRAC (4-5 micron). We find evidence for absorption by at least one of H2O, HCN, CO2, and CH4 (Bayes factor 7.4; 2.5-sigma significance), although the data precision does not allow us to unambiguously discriminate between these molecules. The transmission spectrum rules out cloud-free hydrogen-dominated atmospheres with metallicities <100x solar at >5.8-sigma confidence. In contrast, good agreement with the data is obtained for cloud-free models assuming metallicities >700x solar. However, for retrieval analyses that include the effect of clouds, a much broader range of metallicities (including subsolar) is consistent with the data, due to the degeneracy with cloud-top pressure. Self-consistent chemistry models that account for photochemistry and vertical mixing are presented for the atmosphere of HD3167c. The predictions of these models are broadly consistent with our abundance constraints, although this is primarily due to the large uncertainties on the latter. Interior structure models suggest the core mass fraction is >40%, independent of a rock or water core composition, and independent of atmospheric envelope metallicity up to 1000x solar. We also report abundance measurements for fifteen elements in the host star, showing that it has a very nearly solar composition.

arXiv commentAccepted for publication in the Astronomical Journal

References in corpus (118)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Astropy: A Community Python Package for Astronomy
• emcee: The MCMC Hammer
• The NumPy array: a structure for efficient numerical computation
• The chemical composition of the Sun
• Gaia Data Release 2. Summary of the contents and survey properties
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• The Infrared Array Camera (IRAC) for the Spitzer Space Telescope
• The K2 Mission: Characterization and Early results
• X-ray spectral modelling of the AGN obscuring region in the CDFS: Bayesian model selection and catalogue
• The California-Kepler Survey. III. A Gap in the Radius Distribution of Small Planets
• Bayes in the sky: Bayesian inference and model selection in cosmology
• The false positive rate of Kepler and the occurrence of planets
• batman: BAsic Transit Model cAlculatioN in Python
• The effects of snowlines on C/O in planetary atmospheres
• Planetary Radii across Five Orders of Magnitude in Mass and Stellar Insolation: Application to Transits
• A continuum from clear to cloudy hot-Jupiter exoplanets without primordial water depletion
• Clouds in the atmosphere of the super-Earth exoplanet GJ 1214b
• Kepler planets: a tale of evaporation
• Most 1.6 Earth-Radius Planets are not Rocky
• The evaporation valley in the Kepler planets
• Understanding the Mass-Radius Relation for Sub-Neptunes: Radius as a Proxy for Composition
• The Occurrence Rate of Small Planets around Small Stars
• The Occurrence and Mass Distribution of Close-in Super-Earths, Neptunes, and Jupiters
• A Technique for Extracting Highly Precise Photometry for the Two-Wheeled Kepler Mission
• Growth Model Interpretation of Planet Size Distribution
• The Mass-Radius Relation for 65 Exoplanets Smaller than 4 Earth Radii
• petitRADTRANS: a Python radiative transfer package for exoplanet characterization and retrieval
• Infrared Transmission Spectroscopy of the Exoplanets HD209458b and XO-1b Using the Wide Field Camera-3 on the Hubble Space Telescope
• An asteroseismic view of the radius valley: stripped cores, not born rocky
• The Role of Core Mass in Controlling Evaporation: the Kepler Radius Distribution and the Kepler-36 Density Dichotomy
• Neglected Clouds in T and Y Dwarf Atmospheres
• The Mass-Metallicity Relation for Giant Planets
• Atmospheric Retrieval for Super-Earths: Uniquely Constraining the Atmospheric Composition with Transmission Spectroscopy
• Sculpting the Valley in the Radius Distribution of Small Exoplanets as a by-product of Planet Formation: The Core-Powered Mass-Loss Mechanism
• Characterizing transiting exoplanet atmospheres with JWST
• 3D mixing in hot Jupiter atmospheres. I. application to the day/night cold trap in HD 209458b
• The Flat Transmission Spectrum of the Super-Earth GJ1214b from Wide Field Camera 3 on the Hubble Space Telescope
• The Interior Structure, Composition, and Evolution of Giant Planets
• Spectral Properties of Cool Stars: Extended Abundance Analysis of 1617 Planet Search Stars
• A featureless transmission spectrum for the Neptune-mass exoplanet GJ 436b
• Chaotic star formation and the alignment of stellar rotation with disc and planetary orbital axes
• A Framework for Quantifying the Degeneracies of Exoplanet Interior Compositions
• How to Distinguish between Cloudy Mini-Neptunes and Water/Volatile-Dominated Super-Earths
• Detailed Models of super-Earths: How well can we infer bulk properties?
• A Framework for Characterizing the Atmospheres of Low-Mass Low-Density Transiting Planets
• Transmission Spectra of Three-Dimensional Hot Jupiter Model Atmospheres
• The Effect of Condensates on the Characterization of Transiting Planet Atmospheres with Transmission Spectroscopy
• Compositional diversity in the atmospheres of hot Neptunes, with application to GJ 436b
• Water Vapor and Clouds on the Habitable-Zone Sub-Neptune Exoplanet K2-18b
• Spitzer Secondary Eclipses of the Dense, Modestly-irradiated, Giant Exoplanet HAT-P-20b Using Pixel-Level Decorrelation
• Water Vapour Absorption in the Clear Atmosphere of an exo-Neptune
• Compositional imprints in density-distance-time: a rocky composition for close-in low-mass exoplanets from the location of the valley of evaporation
• Exoplanet population inference and the abundance of Earth analogs from noisy, incomplete catalogs
• An ultrahot gas-giant exoplanet with a stratosphere
• Thermal Emission and Albedo Spectra of Super Earths with Flat Transmission Spectra
• Three Possible Origins for the Gas Layer on GJ 1214b
• A Plateau in the Planet Population Below Twice the Size of Earth
• A Sub-Neptune Exoplanet with a Low-Metallicity Methane-Depleted Atmosphere and Mie-Scattering Clouds
• Atmospheric reconnaissance of the habitable-zone Earth-sized planets orbiting TRAPPIST-1
• Aerosol Composition of Hot Giant Exoplanets Dominated by Silicates and Hydrocarbon Hazes
• Detection of H2O and evidence for TiO/VO in an ultra hot exoplanet atmosphere
• Ocean Planet or Thick Atmosphere: On the Mass-Radius Relationship for Solid Exoplanets with Massive Atmospheres
• Detection of an atmosphere around the super-Earth 55 Cancri e
• Ranges of Atmospheric Mass and Composition of Super Earth Exoplanets
• The cosmic shoreline: the evidence that escape determines which planets have atmospheres, and what this may mean for Proxima Centauri b
• A generalized bayesian inference method for constraining the interiors of super Earths and sub-Neptunes
• Bulk Composition of GJ 1214b and other sub-Neptune exoplanets
• Hubble Space Telescope Near-IR Transmission Spectroscopy of the Super-Earth HD 97658b
• Very Low-Density Planets around Kepler-51 Revealed with Transit Timing Variations and an Anomaly Similar to a Planet-Planet Eclipse Event
• Thermal evolution and structure models of the transiting super-Earth GJ 1214b
• The HST PanCET Program: Exospheric Mg II and Fe II in the Near-UV transmission spectrum of WASP-121b using Jitter Decorrelation
• A new equation of state for dense hydrogen-helium mixtures
• Evolution of the radius valley around low mass stars from $Kepler$ and $K2$
• Pseudo 2D chemical model of hot Jupiter atmospheres: application to HD 209458b and HD 189733b
• Forward and Inverse Modeling of the Emission and Transmission Spectrum of GJ 436b: Investigating Metal Enrichment, Tidal Heating, and Clouds
• Trends in Atmospheric Properties of Neptune-Size Exoplanets
• Connecting Giant Planet Atmosphere and Interior Modeling: Constraints on Atmospheric Metal Enrichment
• A uniform analysis of HD209458b Spitzer/IRAC lightcurves with Gaussian process models
• Irradiated ocean planets bridge super-Earth and sub-Neptune populations
• High-precision abundances of elements in solar-type stars. Evidence of two distinct sequences in abundance-age relations
• Chemical Kinetics on Extrasolar Planets
• Climate of an Ultra hot Jupiter: Spectroscopic phase curve of WASP-18b with HST/WFC3
• Theoretical transmission spectra of exoplanet atmospheres with hydrocarbon haze: Effect of creation, growth, and settling of haze particles. I. Model description and first results
• The Featureless Transmission Spectra of Two Super-Puff Planets
• Mass-Radius Relations and Core-Envelope Decompositions of Super-Earths and Sub-Neptunes
• Vertical Tracer Mixing in Hot Jupiter Atmospheres
• Homogeneous Analysis of Hot Earths: Masses, Sizes, and Compositions
• Three's Company: An additional non-transiting super-Earth in the bright HD 3167 system, and masses for all three planets
• An emission spectrum for WASP-121b measured across the 0.8-1.1 micron wavelength range using the Hubble Space Telescope
• Ab initio based equation of state of dense water for planetary and exoplanetary modeling
• The Transiting System GJ1214: High-Precision Defocused Transit Observations and a Search for Evidence of Transit Timing Variation
• The transiting multi-planet system HD3167: a 5.7 MEarth Super-Earth and a 8.3 MEarth mini-Neptune
• Near-infrared transmission spectrum of the warm-uranus GJ 3470b with the Wide Field Camera-3 on the Hubble Space Telescope
• Strict Upper Limits on the Carbon-to-Oxygen Ratios of Eight Hot Jupiters from Self-Consistent Atmospheric Retrieval
• Updated Parameters and a New Transmission Spectrum of HD 97658b
• Two Small Planets Transiting HD 3167
• Confirmation of water emission in the dayside spectrum of the ultrahot Jupiter WASP-121b
• WASP-127b transmission spectrum]{Abundance measurements of H${}_2$O and carbon-bearing species in the atmosphere of WASP-127b confirm its super-solar metallicity
• A Hubble PanCET Study of HAT-P-11b: A Cloudy Neptune with a Low Atmospheric Metallicity
• An HST/STIS Optical Transmission Spectrum of Warm Neptune GJ 436b
• Nearly Polar orbit of the sub-Neptune HD3167 c: Constraints on a multi-planet system dynamical history
• Into the UV: A precise transmission spectrum of HAT-P-41b using Hubble's WFC3/UVIS G280 grism
• The Exoplanet Population Observation Simulator. II -- Population Synthesis in the Era of Kepler
• Machine learning inference of the interior structure of low-mass exoplanets
• The Hubble PanCET program: An extensive search for metallic ions in the exosphere of GJ 436 b
• Detection of Na, K and H${}_2$O in the hazy atmosphere of WASP-6b
• Close-in sub-Neptunes reveal the past rotation history of their host stars: atmospheric evolution of planets in the HD3167 and K2-32 planetary systems
• Transmission Spectroscopy of WASP-79b from 0.6 to 5.0 $\mu$m
• The HST PanCET Program: An Optical to Infrared Transmission Spectrum of HAT-P-32Ab
• Optical to near-infrared transmission spectrum of the warm sub-Saturn HAT-P-12b
• An Unusual Transmission Spectrum for the Sub-Saturn KELT-11b Suggestive of a Sub-Solar Water Abundance
• Indications for very high metallicity and absence of methane for the eccentric exo-Saturn WASP-117b
• Redshift Space Distortion of 21cm line at 1<z<5 with Cosmological Hydrodynamic Simulations
• How to Characterize the Atmosphere of a Transiting Exoplanet
• K2 Targets Observed with SPHERE/VLT: An M4-7 Dwarf Companion Resolved around EPIC 206011496
• Analyzing Eight Years of Transiting Exoplanet Observations Using WFC3's Spatial Scan Monitor

Cited by in corpus (26)

• Early Release Science of the exoplanet WASP-39b with JWST NIRSpec PRISM
• ARES V: No Evidence For Molecular Absorption in the HST WFC3 Spectrum of GJ 1132 b
• Clouds and Clarity: Revisiting Atmospheric Feature Trends in Neptune-size Exoplanets
• Hubble Space Telescope transmission spectroscopy for the temperate sub-Neptune TOI-270d: a possible hydrogen-rich atmosphere containing water vapour
• TESS-Keck Survey IX: Masses of Three Sub-Neptunes Orbiting HD 191939 and the Discovery of a Warm Jovian Plus a Distant Sub-Stellar Companion
• ATOCA: an algorithm to treat order contamination. Application to the NIRISS SOSS mode
• TOI-1759 b: a transiting sub-Neptune around a low mass star characterized with SPIRou and TESS
• Cleaning our Hazy Lens: Exploring Trends in Transmission Spectra of Warm Exoplanets
• Water absorption in the transmission spectrum of the water-world candidate GJ9827d
• Detecting the proposed CH4-CO2 biosignature pair with the James Webb Space Telescope: TRAPPIST-1e and the effect of cloud/haze
• Importance of Sample Selection in Exoplanet Atmosphere Population Studies
• TKS V. Twin sub-Neptunes Transiting the Nearby G Star HD 63935
• Atmospheric dynamics of temperate sub-Neptunes. Part I: dry dynamics
• A CHEOPS-enhanced view of the HD3167 system
• A sub-Neptune planet around TOI-1695 discovered and characterized with SPIRou and TESS
• HST Transmission Spectra of the Hot-Neptune HD 219666 b: Detection of Water and the Challenge of Constraining Both Water and Methane
• Exploring the atmosphere of GJ 1132 b with CRIRES+
• Evidence for an Atmosphere on the Ultra-Short Period super-Earth HD 3167 b
• Sub-Neptunes as Soot Factories: Deep Atmosphere Hydrocarbon Formation and Quenching as the Origin of Sub-Neptune Aerosol Trends
• JWST unveils a high mean molecular weight atmosphere for mini-Neptune TOI-1130b: Evidence for formation beyond the water ice line
• L 98-59: a Benchmark System of Small Planets for Future Atmospheric Characterization
• Grain Growth in Escaping Atmospheres: Implications for the Radius Inflation of Super-Puffs
• Asymmetry and Variability in the Transmission Spectra of Tidally Locked Habitable Planets
• Photochemistry and Spectral Characterization of Temperate and Gas-Rich Exoplanets
• Rapid Formation of Super-Earths Around Low-Mass Stars
• Impact of Clouds on the Atmosphere-Mantle Interface of Sub-Neptunes