An L Band Spectrum of the Coldest Brown Dwarf

Abstract

The coldest brown dwarf, WISE 0855, is the closest known planetary-mass, free-floating object and has a temperature nearly as cold as the solar system gas giants. Like Jupiter, it is predicted to have an atmosphere rich in methane, water, and ammonia, with clouds of volatile ices. WISE 0855 is faint at near-infrared wavelengths and emits almost all its energy in the mid-infrared. Skemer et al. 2016 presented a spectrum of WISE 0855 from 4.5-5.1 micron (M band), revealing water vapor features. Here, we present a spectrum of WISE 0855 in L band, from 3.4-4.14 micron. We present a set of atmosphere models that include a range of compositions (metallicities and C/O ratios) and water ice clouds. Methane absorption is clearly present in the spectrum. The mid-infrared color can be better matched with a methane abundance that is depleted relative to solar abundance. We find that there is evidence for water ice clouds in the M band spectrum, and we find a lack of phosphine spectral features in both the L and M band spectra. We suggest that a deep continuum opacity source may be obscuring the near-infrared flux, possibly a deep phosphorous-bearing cloud, ammonium dihyrogen phosphate. Observations of WISE 0855 provide critical constraints for cold planetary atmospheres, bridging the temperature range between the long-studied solar system planets and accessible exoplanets. JWST will soon revolutionize our understanding of cold brown dwarfs with high-precision spectroscopy across the infrared, allowing us to study their compositions and cloud properties, and to infer their atmospheric dynamics and formation processes.

arXiv comment19 pages, 21 figures. Accepted for publication in ApJ

References in corpus (48)

• A Non-Gray Theory of Extrasolar Giant Planets and Brown Dwarfs
• The Limiting Effects of Dust in Brown Dwarf Model Atmospheres
• Precipitating Condensation Clouds in Substellar Atmospheres
• A Unified Theory for the Atmospheres of the Hot and Very Hot Jupiters: Two Classes of Irradiated Atmospheres
• The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
• Near-Infrared Photometry and Spectroscopy of L and T Dwarfs: the Effects of Temperature, Clouds, and Gravity
• Line and Mean Opacities for Ultracool Dwarfs and Extrasolar Planets
• Neglected Clouds in T and Y Dwarf Atmospheres
• 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
• Gaseous Mean Opacities for Giant Planet and Ultracool Dwarf Atmospheres over a Range of Metallicities and Temperatures
• Clouds and Chemistry: Ultracool Dwarf Atmospheric Properties from Optical and Infrared Colors
• Albedo and Reflection Spectra of Extrasolar Giant Planets
• Atmospheric Parameters of Field L and T Dwarfs
• Atmospheric, Evolutionary, and Spectral Models of the Brown Dwarf Gliese 229 B
• Reflected Spectra and Albedos of Extrasolar Giant Planets I: Clear and Cloudy Atmospheres
• Beyond the T Dwarfs: Theoretical Spectra, Colors, and Detectability of the Coolest Brown Dwarfs
• Theoretical Spectra and Atmospheres of Extrasolar Giant Planets
• Stellar Abundances in the Solar Neighborhood: The Hypatia Catalog
• Atmospheric Chemistry in Giant Planets, Brown Dwarfs, and Low-Mass Dwarf Stars II. Sulfur and Phosphorus
• Fingering convection and cloudless models for cool brown dwarf atmospheres
• Thermal Emission and Albedo Spectra of Super Earths with Flat Transmission Spectra
• A comparison of chemistry and dust cloud formation in ultracool dwarf model atmospheres
• Quantitatively Assessing the Role of Clouds in the Transmission Spectrum of GJ 1214b
• A Patchy Cloud Model for the L to T Dwarf Transition
• Discovery of a ~250 K Brown Dwarf at 2 pc from the Sun
• Water Clouds in Y Dwarfs and Exoplanets
• Dust in Brown Dwarfs and Extra-solar Planets I. Chemical composition and spectral appearance of quasi-static cloud layers
• Uniform Atmospheric Retrieval Analysis of Ultracool Dwarfs I: Characterizing Benchmarks, Gl570D and HD3651B
• Theory for the Secondary Eclipse Fluxes, Spectra, Atmospheres, and Light Curves of Transiting Extrasolar Giant Planets
• Retrieval of atmospheric properties of cloudy L dwarfs
• The discovery of a very cool, very nearby brown dwarf in the Galactic plane
• Uniform Atmospheric Retrieval Analysis of Ultracool Dwarfs II: Properties of 11 T-dwarfs
• WISE Y Dwarfs As Probes of the Brown Dwarf-Exoplanet Connection
• Phase Functions and Light Curves of Wide Separation Extrasolar Giant Planets
• 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
• Spectral Variability from the Patchy Atmospheres of T and Y Dwarfs
• The Properties of the 500 K Dwarf UGPS J072227.51-054031.2, and a Study of the Far-Red Flux of Cold Brown Dwarfs
• The First Spectrum of the Coldest Brown Dwarf
• Theoretical Radii of Transiting Giant Planets: The Case of OGLE-TR-56b
• Indications of Water Clouds in the Coldest Known Brown Dwarf
• The Spectral Energy Distribution of the Coldest Known Brown Dwarf
• A Signature of Chromospheric Activity in Brown Dwarfs Revealed by 2.5-5.0 Micron AKARI Spectra
• Photometric Monitoring of the Coldest Known Brown Dwarf with the Spitzer Space Telescope
• NEOWISE-R Observation of the Coolest Known Brown Dwarf
• Temperature constraints on the coldest brown dwarf known WISE 0855-0714
• The Collapse of the Wien Tail in the Coldest Brown Dwarf? Hubble Space Telescope Near-Infrared Photometry of WISE J085510.83-071442.5
• Deep $z$-band observations of the coolest Y dwarf

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• An Improved Near-Infrared Spectrum of the Archetype Y Dwarf WISEP J182831.08+265037.8
• Brown Dwarf Atmospheres as the Potentially Most Detectable and Abundant Sites for Life
• Microphysics of Water Clouds in the Atmospheres of Y Dwarfs and Temperate Giant Planets
• Dynamically coupled kinetic chemistry in brown dwarf atmospheres I. Performing global scale kinetic modelling
• Observation of undepleted phosphine in the atmosphere of a low-temperature brown dwarf
• Gemini/GMOS Transmission Spectroscopy of the Grazing Planet Candidate WD 1856+534 b
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• Impacts of Water Latent Heat on the Thermal Structure of Ultra-Cool Objects: Brown Dwarfs and Free-Floating Planets
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• PICASO 4.0: Clouds and Photochemistry in Climate Models of Brown Dwarfs and Exoplanets
• Microphysical Prescriptions for Parameterized Water Cloud Formation on Ultra-cool Substellar Objects
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• 14 Her: a likely case of planet-planet scattering
• Time-resolved JWST Retrieval Analysis of the Coldest Brown Dwarf: Temperature and Chemical Variations in WISE 0855-07