Uniform Atmospheric Retrieval Analysis of Ultracool Dwarfs II: Properties of 11 T-dwarfs

Abstract

Brown dwarf spectra are rich in information revealing of the chemical and physical processes operating in their atmospheres. We apply a recently developed atmospheric retrieval tool to an ensemble of late T-dwarf (600-800K) near infrared spectra. With these spectra we are able to place direct constraints the molecular abundances of H${}_2$O, CH${}_4$, CO, CO${}_2$, NH${}_3$, H${}_2$S, and Na+K, gravity, thermal structure (and effective temperature), photometric radius, and cloud optical depths. We find that ammonia, water, methane, and the alkali metals are present and well constrained in all 11 objects. From the abundance constraints we find no significant trend in the water, methane, or ammonia abundances with temperature, but find a very strong ($>$25$\sigma$) increasing trend in the alkali metal abundances with effective temperature, indicative of alkali rainout. We also find little evidence for optically thick clouds. With the methane and water abundances, we derive the intrinsic atmospheric metallicity and carbon-to-oxygen ratios. We find in our sample, that metallicities are typically sub solar and carbon-to-oxygen ratios are somewhat super solar, different than expectations from the local stellar population. We also find that the retrieved vertical thermal profiles are consistent with radiative equilibrium over the photospheric regions. Finally, we find that our retrieved effective temperatures are lower than previous inferences for some objects and that our radii are larger than expectations from evolutionary models, possibly indicative of un-resolved binaries. This investigation and methodology represents a paradigm in linking spectra to the determination of the fundamental chemical and physical processes governing cool brown dwarf atmospheres.

arXiv commentAccepted ApJ. Supplemental material including full posteriors will be included through the link in the published ApJ article

References in corpus (123)

• emcee: The MCMC Hammer
• Validation of the new Hipparcos reduction
• Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
• Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics
• The Limiting Effects of Dust in Brown Dwarf Model Atmospheres
• Galactic Chemical Evolution: Hydrogen Through Zinc
• Ages for illustrative field stars using gyrochronology: viability, limitations and errors
• Precipitating Condensation Clouds in Substellar Atmospheres
• New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey
• The Theory of Brown Dwarfs and Extrasolar Giant Planets
• Stellar Chemical Signatures And Hierarchical Galaxy Formation
• The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
• Temperate Earth-sized planets transiting a nearby ultracool dwarf star
• Evolutionary models for low-mass stars and brown dwarfs: uncertainties and limits at very young ages
• Theory of Low-Mass Stars and Substellar Objects
• The Hawaii Infrared Parallax Program. I. Ultracool Binaries and the L/T Transition
• Near-Infrared Photometry and Spectroscopy of L and T Dwarfs: the Effects of Temperature, Clouds, and Gravity
• Chemical Equilibrium Abundances in Brown Dwarf and Extrasolar Giant Planet Atmospheres
• Line and Mean Opacities for Ultracool Dwarfs and Extrasolar Planets
• A Unified Near Infrared Spectral Classification Scheme for T Dwarfs
• Neglected Clouds in T and Y Dwarf Atmospheres
• Atmospheric Retrieval for Super-Earths: Uniquely Constraining the Atmospheric Composition with Transmission Spectroscopy
• The Spectra of T Dwarfs I: Near-Infrared Data and Spectral Classification
• Binarity in Brown Dwarfs: T Dwarf Binaries Discovered with the Hubble Space Telescope WPFC2
• The Mauna Kea Observatories Near-Infrared Filter Set. II. Specifications for a New JHKL'M' Filter Set for Infrared Astronomy
• L and T Dwarf Models and the L to T Transition
• The 0.8-14.5 micron Spectra of Mid-L to Mid-T Dwarfs: Diagnostics of Effective Temperature, Grain Sedimentation, Gas Transport, and Surface Gravity
• A Systematic Retrieval Analysis of Secondary Eclipse Spectra I: A Comparison of Atmospheric Retrieval Techniques
• Gaseous Mean Opacities for Giant Planet and Ultracool Dwarf Atmospheres over a Range of Metallicities and Temperatures
• Fundamental Parameters and Spectral Energy Distributions of Young and Field Age Objects with Masses Spanning the Stellar to Planetary Regime
• Atomic and Molecular Opacities for Brown Dwarf and Giant Planet Atmospheres
• Atmospheric Parameters of Field L and T Dwarfs
• Atmospheric, Evolutionary, and Spectral Models of the Brown Dwarf Gliese 229 B
• Infrared Photometry of Late-M, L, and T Dwarfs
• The Compositional Diversity of Extrasolar Terrestrial Planets: I. In-Situ Simulations
• KELT-1b: A Strongly Irradiated, Highly Inflated, Short Period, 27 Jupiter-mass Companion Transiting a mid-F Star
• Stellar Abundances in the Solar Neighborhood: The Hypatia Catalog
• Tau-REx I: A next generation retrieval code for exoplanetary atmospheres
• The Brown Dwarf Kinematics Project (BDKP). III. Parallaxes for 70 Ultracool Dwarfs
• Masses, Radii, and Cloud Properties of the HR 8799 Planets
• Atmospheric Chemistry in Giant Planets, Brown Dwarfs, and Low-Mass Dwarf Stars II. Sulfur and Phosphorus
• Weather on Other Worlds. II. Survey Results: Spots Are Ubiquitous on L and T Dwarfs
• Fingering convection and cloudless models for cool brown dwarf atmospheres
• Atmospheric Chemistry in Giant Planets, Brown Dwarfs, and Low-Mass Dwarf Stars III. Iron, Magnesium, and Silicon
• Infrared Parallaxes for Methane T dwarfs
• Exploring Exoplanet Populations with NASA's Kepler Mission
• Discovery of a Brown Dwarf Companion to Gliese 570ABC: A 2MASS T Dwarf Significantly Cooler than Gliese 229B
• Discovery of Two T Dwarf Companions with the Spitzer Space Telescope
• A Systematic Retrieval Analysis of Secondary Eclipse Spectra II: A Uniform Analysis of Eight Planets and Their C to O Ratios
• The Mauna Kea Observatories Near-Infrared Filter Set. I: Defining Optimal 1-5 $\mu$m Bandpasses
• Hubble Space Telescope NICMOS Observations of T Dwarfs: Brown Dwarf Multiplicity and New Probes of the L/T Transition
• On the Cool Side: Modeling the Atmospheres of Brown Dwarfs and Giant Planets
• Strong Brightness Variations Signal Cloudy-to-Clear Transition of Brown Dwarfs
• On the Anomalous Radii of the Transiting Extrasolar Planets
• Ammonia as a tracer of chemical equilibrium in the T7.5 dwarf Gliese 570D
• A Method for Determining the Physical Properties of the Coldest Known Brown Dwarfs
• Individual Dynamical Masses of Ultracool Dwarfs
• Optimal Estimation Retrievals of the Atmospheric Structure and Composition of HD 189733b from Secondary Eclipse Spectroscopy
• Mid-Infrared Photometry of Cold Brown Dwarfs: Diversity in Age, Mass and Metallicity
• No Thermal Inversion and a Solar Water Abundance for the Hot Jupiter HD209458b from HST WFC3 Emission Spectroscopy
• Uniform Atmospheric Retrieval Analysis of Ultracool Dwarfs I: Characterizing Benchmarks, Gl570D and HD3651B
• Discovery of 11 New T Dwarfs in the Two Micron All-Sky Survey, Including a Possible L/T Transition Binary
• Tau-REx II: Retrieval of emission spectra
• A Systematic Study of Departures from Chemical Equilibrium in the Atmospheres of Substellar Mass Objects
• Information Content of Exoplanetary Transit Spectra: An Initial Look
• Constructing A Flexible Likelihood Function For Spectroscopic Inference
• Age consistency between exoplanet hosts and field stars
• Clouds in the Coldest Brown Dwarfs: FIRE Spectroscopy of Ross 458C
• The 2MASS Wide-Field T Dwarf Search. IV Unting out T dwarfs with Methane Imaging
• The Helium abundance and Delta Y / Delta Z in Lower Main Sequence stars
• Deciphering the Atmospheric Composition of WASP-12b: A Comprehensive Analysis of its Dayside Emission
• Physical parameters of two very cool T dwarfs
• Hubble Space Telescope Spectroscopy of Brown Dwarfs Discovered with the Wide-field Infrared Survey Explorer
• Transiting exoplanets from the CoRoT space mission. XV. CoRoT-15b: a brown dwarf transiting companion
• The potential for Earth-mass planet formation around brown dwarfs
• On the Distribution of Orbital Eccentricities for Very Low-Mass Binaries
• Physical and Spectral Characteristics of the T8 and Later-Type Dwarfs
• On the Carbon-to-Oxygen Ratio Measurement in Nearby Sunlike Stars: Implications for Planet Formation and the Determination of Stellar Abundances
• HD3651B: the first directly imaged brown dwarf companion of an exoplanet host star
• LHS6343C: A Transiting Field Brown Dwarf Discovered by the Kepler Mission
• Physical Properties of Young Brown Dwarfs and Very Low-Mass Stars Inferred from High-Resolution Model Spectra
• 3.6-7.9 um Photometry of L and T Dwarfs and the Prevalence of Vertical Mixing in their Atmospheres
• C/O Ratios of Stars with Transiting Hot Jupiter Exoplanets
• Accurate M Dwarf Metallicities from Spectral Synthesis: A Critical Test of Model Atmospheres
• Two Extraordinary Substellar Binaries at the T/Y Transition and the Y-Band Fluxes of the Coolest Brown Dwarfs
• Clouds on the hot Jupiter HD189733b: constraints from the reflection spectrum
• The Physical Properties of Four ~600K T Dwarfs
• The Late-T Dwarf Companion to the Exoplanet Host Star HD 3651: A New Benchmark for Gravity and Metallicity Effects in Ultracool Spectra
• Age Determination for 346 Nearby Stars in the Herschel DEBRIS Survey
• Carbon and Oxygen in Nearby Stars: Keys to Protoplanetary Disk Chemistry
• CFBDSIR J1458+1013B: A Very Cold (>T10) Brown Dwarf in a Binary System
• The Physical Properties of HD 3651B: An Extrasolar Nemesis?
• An independent analysis of the brown dwarf atmosphere monitoring (BAM) data: large-amplitude variability is rare outside the L/T transition
• The Brown dwarf Atmosphere Monitoring (BAM) Project I: The largest near-IR monitoring survey of L- & T-dwarfs
• AKARI Observations of Brown Dwarfs. III. CO, CO2 and CH4 Fundamental Bands and Physical Parameters
• A Comparison of Stellar Elemental Abundance Techniques and Measurements
• The discovery of a very cool binary system
• Temperature Fluctuations as a Source of Brown Dwarf Variability
• ULAS J141623.94$+$134836.3 - a faint common proper motion companion of a nearby L dwarf. Serendipitous discovery of a cool brown dwarf in UKIDSS DR6
• Microlensing Discovery of a Tight, Low Mass-ratio Planetary-mass Object around an Old, Field Brown Dwarf
• AKARI Observations of Brown Dwarfs I.: CO and CO_2 Bands in the Near-Infrared Spectra
• Spectroscopy across the brown dwarf/planetary mass boundary - I. Near-infrared JHK spectra
• The Properties of the 500 K Dwarf UGPS J072227.51-054031.2, and a Study of the Far-Red Flux of Cold Brown Dwarfs
• Constraining the atmosphere of GJ 1214b using an optimal estimation technique
• Carbon Dioxide in Exoplanetary Atmospheres: Rarely Dominant Compared to Carbon Monoxide and Water in Hot, Hydrogen-dominated Atmospheres
• Spectroscopic Detection of Carbon Monoxide in Two Late-type T Dwarfs
• Radii, masses, and ages of 18 bright stars using interferometry and new estimations of exoplanetary parameters
• SDSS J141624.08+134826.7: A Nearby Blue L Dwarf From the Sloan Digital Sky Survey
• Discovery of An Unusually Blue L Dwarf Within 10 pc of the Sun
• Methane and Ammonia in the near-infrared spectra of late T dwarfs
• The Chemical Evolution of Globular Clusters I. Reactive Elements and Non-Metals
• ULAS J141623.94+134836.3: a Blue T Dwarf Companion to a Blue L Dwarf
• The galactic unclassified B[e] star HD 50138. II. Interferometric constraints on the close circumstellar environment
• A Search for Photometric Variability in L and T type Brown Dwarf Atmospheres
• A Signature of Chromospheric Activity in Brown Dwarfs Revealed by 2.5-5.0 Micron AKARI Spectra
• An Approach for Retrieving Temperatures and Abundances in Brown Dwarf Atmospheres
• Discovery of a Low-Luminosity, Tight Substellar Binary at the T/Y Transition
• Akari Observations of Brown Dwarfs. II CO2 as Probe of Carbon and Oxygen Abundances in Brown Dwarfs
• Physical parameters of T dwarfs derived from high-resolution near-infrared spectra
• Effects of Latent Heating on Atmospheres of Brown Dwarfs and Directly Imaged Planets
• Constraints on the binary Properties of mid to late T dwarfs from Hubble Space Telescope WFC3 Observations
• Habitable Planets Eclipsing Brown Dwarfs: Strategies for Detection and Characterization
• Resolved Spectroscopy of the T8.5 and Y0-0.5 Binary WISEPC J121756.91+162640.2AB

Cited by in corpus (79)

• petitRADTRANS: a Python radiative transfer package for exoplanet characterization and retrieval
• Exoplanetary Atmospheres: Key Insights, Challenges and Prospects
• A new set of atmosphere and evolution models for cool T-Y brown dwarfs and giant exoplanets
• Retrieving Temperatures and Abundances of Exoplanet Atmospheres with High-Resolution Cross-Correlation Spectroscopy
• Retrieving scattering clouds and disequilibrium chemistry in the atmosphere of HR 8799e
• A solar C/O and sub-solar metallicity in a hot Jupiter atmosphere
• Peering into the formation history of beta Pictoris b with VLTI/GRAVITY long baseline interferometry
• Preliminary Trigonometric Parallaxes of 184 Late-T and Y Dwarfs and an Analysis of the Field Substellar Mass Function into the "Planetary" Mass Regime
• PICASO 3.0: A One-Dimensional Climate Model for Giant Planets and Brown Dwarfs
• Beyond Equilibrium Temperature: How the Atmosphere/Interior Connection Affects the Onset of Methane, Ammonia, and Clouds in Warm Transiting Giant Planets
• Aerosols in Exoplanet Atmospheres
• Cloud busting: enstatite and quartz clouds in the atmosphere of 2M2224-0158
• The Sonora Substellar Atmosphere Models. IV. Elf Owl: Atmospheric Mixing and Chemical Disequilibrium with Varying Metallicity and C/O Ratios
• Atmospheric Regimes and Trends on Exoplanets and Brown Dwarfs
• Sulphur dioxide in the mid-infrared transmission spectrum of WASP-39b
• Observations of Disequilibrium CO Chemistry in the Coldest Brown Dwarfs
• The SPHINX M-dwarf Spectral Grid. I. Benchmarking New Model Atmospheres to Derive Fundamental M-Dwarf Properties
• The GJ 504 system revisited. Combining interferometric, radial velocity, and high contrast imaging data
• A Uniform Retrieval Analysis of Ultracool Dwarfs. III. Properties of Y-Dwarfs
• Patchy Forsterite Clouds in the Atmospheres of Two Highly Variable Exoplanet Analogs
• An L Band Spectrum of the Coldest Brown Dwarf
• HyDRA-H: Simultaneous Hybrid Retrieval of Exoplanetary Emission Spectra
• A Dynamical Mass of $70\pm 5$ Jupiter Masses for Gliese 229B, the First T Dwarf
• New Candidate Extreme T Subdwarfs from the Backyard Worlds: Planet 9 Citizen Science Project
• Atmospheric variability driven by radiative cloud feedback in brown dwarfs and directly imaged extrasolar giant planets
• From cold to hot irradiated gaseous exoplanets: Fingerprints of chemical disequilibrium in atmospheric spectra
• Retrieval of SDSS J1416+1348AB
• The composition of hot Jupiter atmospheres assembled within chemically evolved protoplanetary discs
• From cold to hot irradiated gaseous exoplanets: Toward an observation-based classification scheme
• Y dwarf Trigonometric Parallaxes from the Spitzer Space Telescope
• On the Chemical Abundance of HR 8799 and the Planet c
• Measuring the D/H Ratios of Exoplanets and Brown Dwarfs
• Exploring the Extremes: Characterizing a New Population of Old and Cold Brown Dwarfs
• Retrieval Study of Brown Dwarfs Across the L-T Sequence
• Uniform Forward-Modeling Analysis of Ultracool Dwarfs. II. Atmospheric Properties of 55 Late-T Dwarfs
• Cloud Atlas: Hubble Space Telescope Near-Infrared Spectral Library of Brown Dwarfs, Planetary-mass companions, and hot Jupiters
• A data-driven approach to constraining the atmospheric temperature structure of KELT-9b
• The ESO SupJup Survey I: Chemical and isotopic characterisation of the late L-dwarf DENIS J0255-4700 with CRIRES${}^{+}$
• Considerations for Atmospheric Retrieval of High-Precision Brown Dwarf Spectra
• Molecular mapping of the PDS70 system: No molecular absorption signatures from the forming planet PDS70 b
• Uniform Forward-Modeling Analysis of Ultracool Dwarfs. I. Methodology and Benchmarking
• Methane Emission From a Cool Brown Dwarf
• Retrieval study of cool, directly imaged exoplanet 51 Eri b
• Revisiting the atmosphere of the exoplanet 51 Eridani b with VLT/SPHERE
• A 1.46-2.48 $\mu$m Spectroscopic Atlas of a T6 Dwarf (1060 K) Atmosphere with IGRINS: First Detections of H${}_2$S and H${}_2$, and Verification of H${}_2$O, CH${}_4$, and NH${}_3$ Line Lists
• Wolf 1130: A Nearby Triple System Containing a Cool, Ultramassive White Dwarf
• An Atmospheric Retrieval of the Brown Dwarf Gliese 229B
• The PHOENIX Exoplanet Retrieval Algorithm and Using H${}^{-}$ Opacity as a Probe in Ultra-hot Jupiters
• Supervised Machine Learning for Intercomparison of Model Grids of Brown Dwarfs: Application to GJ 570D and the Epsilon Indi B Binary System
• Towards Robust Atmospheric Retrieval on Cloudy L Dwarfs: The Impact of Thermal and Abundance Profile Assumptions
• Primeval very low-mass stars and brown dwarfs - III. The halo transitional brown dwarfs
• A Wide Planetary Mass Companion Discovered Through the Citizen Science Project Backyard Worlds: Planet 9
• The first retrieval of a substellar subdwarf: A cloud-free SDSS J125637.13-022452.4
• Evidence for SiO cloud nucleation in the rogue planet PSO J318
• The JWST Weather Report: retrieving temperature variations, auroral heating, and static cloud coverage on SIMP-0136
• The puzzle of the formation of T8 dwarf Ross 458c
• Detection of Na and K in the atmosphere of the hot Jupiter HAT-P-1b with P200/DBSP
• A Comparative L-dwarf Sample Exploring the Interplay Between Atmospheric Assumptions and Data Properties
• CWISE J014611.20-050850.0AB: The Widest Known Brown Dwarf Binary in the Field
• Retrieving Exoplanet Atmospheres using Planetary Infrared Excess: Prospects for the Nightside of WASP-43 b and other Hot Jupiters
• CROCODILE \\ Incorporating medium-resolution spectroscopy of close-in directly imaged exoplanets into atmospheric retrievals via cross-correlation
• Atmospheric abundances and bulk properties of the binary brown dwarf Gliese 229 Bab from JWST/MIRI spectroscopy
• ACCESS: Tentative detection of H${}_2$O in the ground-based optical transmission spectrum of the low-density hot Saturn HATS-5b
• Investigating Possible Binarity for GJ 229B
• Measurement of stellar and substellar winds using white dwarf hosts
• Large Scale Searches for Brown Dwarfs and Free-Floating Planets
• Probing Late-type T dwarf J-H Color Outliers for Signs of Age
• The Sonora Brown Dwarf Atmosphere and Evolution Models I. Model Description and Application to Cloudless Atmospheres in Rainout Chemical Equilibrium
• Interpreting the atmospheric composition of exoplanets: sensitivity to planet formation assumptions
• The Brown Dwarf Kinematics Project (BDKP). V. Radial and Rotational Velocities of T Dwarfs from Keck/NIRSPEC High-Resolution Spectroscopy
• Phase-resolved Hubble Space Telescope WFC3 Spectroscopy of Weakly-Irradiated Brown Dwarf GD 1400 and Energy Redistribution-Irradiation Trends in Six WD$-$BD Binaries
• Assessing robustness and bias in 1D retrievals of 3D Global Circulation Models at high spectral resolution: a WASP-76 b simulation case study in emission
• First Results from WINERED: Detection of Emission Lines from Neutral Iron and a Combined Set of Trace Species on the Dayside of WASP-189 b
• Alkali Metallicity, Mineral Clouds, and Deep Atmospheric Variability on Jupiter
• A Uniform Retrieval Analysis of Ultra-cool Dwarfs. IV. A Statistical Census from 50 Late-T Dwarfs
• JWST high-contrast spectroscopy with speckle modelling: Atmospheric retrievals of the T dwarf companion HD 19467 B
• Ross 19B: An Extremely Cold Companion Discovered via the Backyard Worlds: Planet 9 Citizen Science Project
• Panchromatic characterization of the Y0 brown dwarf WISEP J173835.52+273258.9 using JWST/MIRI
• Time-resolved JWST Retrieval Analysis of the Coldest Brown Dwarf: Temperature and Chemical Variations in WISE 0855-07