Spectroscopic Detection of Carbon Monoxide in Two Late-type T Dwarfs

Abstract

M band spectra of two late-type T dwarfs, 2MASS J09373487+2931409, and Gliese 570D, confirm evidence from photometry that photospheric CO is present at abundance levels far in excess of those predicted from chemical equilibrium. These new and unambiguous detections of CO, together with an earlier spectroscopic detection of CO in Gliese 229B and existing M band photometry of a large selection of T dwarfs, suggest that vertical mixing in the photosphere drives the CO abundance out of chemical equilibrium and is a common, and likely universal feature of mid-to-late type T dwarfs. The M band spectra allow determinations of the time scale of vertical mixing in the atmosphere of each object, the first such measurements of this important parameter in late T dwarfs. A detailed analysis of the spectral energy distribution of 2MASS J09373487+2931409 results in the following values for metallicity, temperature, surface gravity, and luminosity: [M/H]~-0.3, T_eff=925-975K, log g=5.20-5.47, log L/L_sun=-5.308 +/- 0.027. The age is 3-10 Gyr and the mass is in the range 45-69 M_Jup.

36 pages incl. 12 figures and 3 tables, accepted by ApJ

References in corpus (9)

• The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
• Line and Mean Opacities for Ultracool Dwarfs and Extrasolar Planets
• Ammonia as a tracer of chemical equilibrium in the T7.5 dwarf Gliese 570D
• Spitzer/IRAC Photometry of M, L, and T Dwarfs
• A Systematic Study of Departures from Chemical Equilibrium in the Atmospheres of Substellar Mass Objects
• Spectroscopic rotational velocities of brown dwarfs
• Physical parameters of two very cool T dwarfs
• Physical and Spectral Characteristics of the T8 and Later-Type Dwarfs
• 3.6-7.9 um Photometry of L and T Dwarfs and the Prevalence of Vertical Mixing in their Atmospheres

Cited by in corpus (50)

• Atmospheric circulation of hot Jupiters: Coupled radiative-dynamical general circulation model simulations of HD 189733b and HD 209458b
• Disequilibrium Carbon, Oxygen, and Nitrogen Chemistry in the Atmospheres of HD 189733b and HD 209458b
• Neglected Clouds in T and Y Dwarf Atmospheres
• The Discovery of Y Dwarfs Using Data from the Wide-field Infrared Survey Explorer (WISE)
• 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
• Clouds and Chemistry in the Atmosphere of Extrasolar Planet HR8799b
• A new set of atmosphere and evolution models for cool T-Y brown dwarfs and giant exoplanets
• Transmission Spectra of Three-Dimensional Hot Jupiter Model Atmospheres
• Masses, Radii, and Cloud Properties of the HR 8799 Planets
• Methane, Carbon Monoxide, and Ammonia in Brown Dwarfs and Self-Luminous Giant Planets
• Near-Infrared Spectroscopy of the Extrasolar Planet HR 8799 b
• On the Cool Side: Modeling the Atmospheres of Brown Dwarfs and Giant Planets
• Quenching of Carbon Monoxide and Methane in the Atmospheres of Cool Brown Dwarfs and Hot Jupiters
• Mid-Infrared Photometry of Cold Brown Dwarfs: Diversity in Age, Mass and Metallicity
• Directly Imaged L-T Transition Exoplanets in the Mid-Infrared
• New H2 collision-induced absorption and NH3 opacity and the spectra of the coolest brown dwarfs
• The Young Planet-mass Object 2M1207b: a cool, cloudy, and methane-poor atmosphere
• The role of convection, overshoot, and gravity waves for the transport of dust in M dwarf and brown dwarf atmospheres
• PICASO 3.0: A One-Dimensional Climate Model for Giant Planets and Brown Dwarfs
• Chemical Kinetics on Extrasolar Planets
• Uniform Atmospheric Retrieval Analysis of Ultracool Dwarfs II: Properties of 11 T-dwarfs
• The Sonora Substellar Atmosphere Models. IV. Elf Owl: Atmospheric Mixing and Chemical Disequilibrium with Varying Metallicity and C/O Ratios
• Observations of Disequilibrium CO Chemistry in the Coldest Brown Dwarfs
• The Y-Type Brown Dwarfs: Estimates of Mass and Age from New Astrometry, Homogenized Photometry and Near-Infrared Spectroscopy
• A Comparison of Near-Infrared Photometry and Spectra for Y Dwarfs with a New Generation of Cool Cloudy Models
• The GJ 504 system revisited. Combining interferometric, radial velocity, and high contrast imaging data
• AKARI Observations of Brown Dwarfs. III. CO, CO2 and CH4 Fundamental Bands and Physical Parameters
• The discovery of a very cool binary system
• AKARI Observations of Brown Dwarfs I.: CO and CO_2 Bands in the Near-Infrared Spectra
• The Sonora Substellar Atmosphere Models. II. Cholla: A Grid of Cloud-free, Solar Metallicity Models in Chemical Disequilibrium for the JWST Era
• Probing the Extent of Vertical Mixing in Brown Dwarf Atmospheres with Disequilibrium Chemistry
• The First Spectrum of the Coldest Brown Dwarf
• Methane and Ammonia in the near-infrared spectra of late T dwarfs
• ULAS J141623.94+134836.3: a Blue T Dwarf Companion to a Blue L Dwarf
• An Approach for Retrieving Temperatures and Abundances in Brown Dwarf Atmospheres
• SDSS J141624.08+134826.7: Blue L Dwarfs and Non-Equilibrium Chemistry
• A deep WISE search for very late type objects and the discovery of two halo/thick-disk T dwarfs: WISE 0013+0634 and WISE 0833+0052
• Uniform Forward-Modeling Analysis of Ultracool Dwarfs. I. Methodology and Benchmarking
• Considerations for Atmospheric Retrieval of High-Precision Brown Dwarf Spectra
• 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
• The role of clouds on the depletion of methane and water dominance in the transmission spectra of irradiated exoplanets
• Near-Infrared Spectroscopy of the Y0 WISEP J173835.52+273258.9 and the Y1 WISE J035000.32-565830.2: the Importance of Non-Equilibrium Chemistry
• Supervised Machine Learning for Intercomparison of Model Grids of Brown Dwarfs: Application to GJ 570D and the Epsilon Indi B Binary System
• Data availability and requirements relevant for the Ariel space mission and other exoplanet atmosphere applications
• Properties of the T8.5 Dwarf Wolf 940 B
• Convective dynamics and disequilibrium chemistry in the atmospheres of giant planets and brown dwarfs
• Dynamically coupled kinetic chemistry in brown dwarf atmospheres I. Performing global scale kinetic modelling
• The infrared colors of 51 Eridani b: micrometereoid dust or chemical disequilibrium?
• Near-infrared spectroscopic characterisation of Gaia ultra-cool dwarf candidates; Spectral types and peculiarities
• A Uniform Retrieval Analysis of Ultra-cool Dwarfs. IV. A Statistical Census from 50 Late-T Dwarfs