An Improved Near-Infrared Spectrum of the Archetype Y Dwarf WISEP J182831.08+265037.8

Abstract

We present a Hubble Space Telescope/Wide-Field Camera 3 near infrared spectrum of the archetype Y dwarf WISEP 182831.08+265037.8. The spectrum covers the 0.9-1.7 um wavelength range at a resolving power of lambda/Delta lambda ~180 and is a significant improvement over the previously published spectrum because it covers a broader wavelength range and is uncontaminated by light from a background star. The spectrum is unique for a cool brown dwarf in that the flux peaks in the Y, J, and H band are of near equal intensity in units of f_lambda. We fail to detect any absorption bands of NH_3 in the spectrum, in contrast to the predictions of chemical equilibrium models, but tentatively identify CH_4 as the carrier of an unknown absorption feature centered at 1.015 um. Using previously published ground- and spaced-based photometry, and using a Rayleigh Jeans tail to account for flux emerging longward of 4.5 um, we compute a bolometric luminosity of log (L_bol/L_sun)=-6.50+-0.02 which is significantly lower than previously published results. Finally, we compare the spectrum and photometry to two sets of atmospheric models and find that best overall match to the observed properties of WISEP 182831.08+265037.8 is a ~1 Gyr old binary composed of two T_eff~325 K, ~5 M_Jup brown dwarfs with subsolar [C/O] ratios.

arXiv commentAccepted for publication in the Astrophysical Journal

References in corpus (58)

• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• Precipitating Condensation Clouds in Substellar Atmospheres
• The Theory of Brown Dwarfs and Extrasolar Giant Planets
• The Infrared Telescope Facility (IRTF) Spectral Library: Cool Stars
• Astrometry and Photometry for Cool Dwarfs and Brown Dwarfs
• Absolute Calibration of the Infrared Array Camera on the Spitzer Space Telescope
• A Unified Near Infrared Spectral Classification Scheme for T Dwarfs
• ExoMol line lists IV: The rotation-vibration spectrum of methane up to 1500 K
• The First Hundred Brown Dwarfs Discovered by the Wide-field Infrared Survey Explorer (WISE)
• 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
• Further Defining Spectral Type "Y" and Exploring the Low-mass End of the Field Brown Dwarf Mass Function
• A variationally computed line list for hot NH3
• Fundamental Parameters and Spectral Energy Distributions of Young and Field Age Objects with Masses Spanning the Stellar to Planetary Regime
• Atmospheric Parameters of Field L and T Dwarfs
• The CatWISE2020 Catalog
• Beyond the T Dwarfs: Theoretical Spectra, Colors, and Detectability of the Coolest Brown Dwarfs
• Distances, Luminosities, and Temperatures of the Coldest Known Substellar Objects
• Spitzer Infrared Spectrograph Observations of M, L, and T Dwarfs
• A Patchy Cloud Model for the L to T Dwarf Transition
• The Mauna Kea Observatories Near-Infrared Filter Set. III. Isophotal Wavelengths and Absolute Calibration
• Ammonia as a tracer of chemical equilibrium in the T7.5 dwarf Gliese 570D
• Discovery of a ~250 K Brown Dwarf at 2 pc from the Sun
• Water Clouds in Y Dwarfs and Exoplanets
• Discovery of a Candidate for the Coolest Known Brown Dwarf
• The Spectra of T Dwarfs. II. Red Optical Data
• The Field Substellar Mass Function Based on the Full-sky 20-pc Census of 525 L, T, and Y Dwarfs
• Molecular Abundances in the Atmosphere of the T Dwarf Gl 229B
• A Systematic Study of Departures from Chemical Equilibrium in the Atmospheres of Substellar Mass Objects
• CFBDS J005910.90-011401.3: reaching the T-Y Brown Dwarf transition?
• New H2 collision-induced absorption and NH3 opacity and the spectra of the coolest brown dwarfs
• Preliminary Trigonometric Parallaxes of 184 Late-T and Y Dwarfs and an Analysis of the Field Substellar Mass Function into the "Planetary" Mass Regime
• Exploring the substellar temperature regime down to ~550K
• Hubble Space Telescope Spectroscopy of Brown Dwarfs Discovered with the Wide-field Infrared Survey Explorer
• Physical and Spectral Characteristics of the T8 and Later-Type Dwarfs
• 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
• Near-infrared photometry of Y dwarfs: low ammonia abundance and the onset of water clouds
• A Comparison of Near-Infrared Photometry and Spectra for Y Dwarfs with a New Generation of Cool Cloudy Models
• CFBDSIR J1458+1013B: A Very Cold (>T10) Brown Dwarf in a Binary System
• Finding ultracool brown dwarfs with MegaCam on CFHT: method and first results
• The Luminosities of the Coldest Brown Dwarfs
• A Uniform Retrieval Analysis of Ultracool Dwarfs. III. Properties of Y-Dwarfs
• An L Band Spectrum of the Coldest Brown Dwarf
• Extending the Canada-France brown Dwarfs Survey to the near-infrared: first ultracool brown dwarfs from CFBDSIR
• Expanding the Y Dwarf Census with Spitzer Follow-up of the Coldest CatWISE Solar Neighborhood Discoveries
• The Coldest Brown Dwarf (Or Free Floating Planet)?: The Y Dwarf WISE 1828+2650
• IAU 2015 Resolution B3 on Recommended Nominal Conversion Constants for Selected Solar and Planetary Properties
• Indications of Water Clouds in the Coldest Known Brown Dwarf
• The Spectral Energy Distribution of the Coldest Known Brown Dwarf
• WISEA J083011.95+283716.0: A Missing Link Planetary-Mass Object
• FIRE Spectroscopy of the ultra-cool brown dwarf, UGPS J072227.51-054031.2: Kinematics, Rotation and Atmospheric Parameters
• CWISEP J193518.59$-$154620.3: An Extremely Cold Brown Dwarf in the Solar Neighborhood Discovered with CatWISE
• The Collapse of the Wien Tail in the Coldest Brown Dwarf? Hubble Space Telescope Near-Infrared Photometry of WISE J085510.83-071442.5
• Improved infrared photometry and a preliminary parallax measurement for the extremely cold brown dwarf CWISEP J144606.62$-$231717.8
• GTC OSIRIS z-band imaging of Y dwarfs
• The Future of Ultracool Dwarf Science with JWST

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• Self-consistent Models of Y Dwarf Atmospheres with Water Clouds and Disequilibrium Chemistry
• The First JWST Spectral Energy Distribution of a Y dwarf
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• JWST Observations of the Enigmatic Y Dwarf WISE 1828+2650: I. Limits to a Binary Companion
• Ammonia-methane ratios from H-band near-infrared spectra of late-T and Y dwarfs
• Optical Properties of Metal-poor T Dwarf Candidates
• A grid of self-consistent MSG (MARCS-StaticWeather-GGchem) cool stellar, sub-stellar, and exoplanetary model atmospheres