Discovery of the Y1 Dwarf WISE J064723.23-623235.5

Abstract

We present the discovery of a very cold, very low mass, nearby brown dwarf using data from the NASA Wide-field Infrared Survey Explorer (WISE). The object, WISE J064723.23-623235.5, has a very red WISE color of W1-W2 > 3.77 mag and a very red Spitzer Space Telescope color of ch1-ch2 = 2.82+/-0.09 mag. In J_MKO-ch2 color (7.58+/-0.27 mag) it is one of the two or three reddest brown dwarfs known. Our grism spectrum from the Hubble Space Telescope (HST) confirms it to be the seventeenth Y dwarf discovered, and its spectral type of Y1+/-0.5 makes it one of the four latest-type Y dwarfs classified. Astrometric imaging from Spitzer and HST, combined with data from WISE, provides a preliminary parallax of pi = 115+/-12 mas (d = 8.7+/-0.9 pc) and proper motion of mu = 387+/-25 mas/yr based on 2.5 years of monitoring. The spectrum implies a blue J-H color, for which model atmosphere calculations suggest a relatively low surface gravity. The best fit to these models indicates an effective temperature of 350-400K and a mass of ~5-30 M_Jup. Kinematic analysis hints that this object may belong to the Columba moving group, which would support an age of ~30 Myr and thus an even lower mass of <2 M_Jup, but verification would require a radial velocity measurement not currently possible for a J=22.7 mag brown dwarf.

arXiv comment26 pages, 7 figures; accepted for publication in The Astrophysical Journal

References in corpus (32)

• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• The Infrared Array Camera (IRAC) for the Spitzer Space Telescope
• The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
• An Infrared Spectroscopic Sequence of M, L and T Dwarfs
• The Hawaii Infrared Parallax Program. I. Ultracool Binaries and the L/T Transition
• Unbound or Distant Planetary Mass Population Detected by Gravitational Microlensing
• Neglected Clouds in T and Y Dwarf Atmospheres
• 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)
• Further Defining Spectral Type "Y" and Exploring the Low-mass End of the Field Brown Dwarf Mass Function
• Bayesian analysis to identify new star candidates in nearby young stellar kinematic groups
• Beyond the T Dwarfs: Theoretical Spectra, Colors, and Detectability of the Coolest Brown Dwarfs
• The Carnegie Supernova Project: The Low-Redshift Survey
• HST Spectral Mapping of L/T Transition Brown Dwarfs Reveals Cloud Thickness Variations
• Discovery of a Candidate for the Coolest Known Brown Dwarf
• Vertical Atmospheric Structure in a Variable Brown Dwarf: Pressure-dependent Phase Shifts in Simultaneous Hubble Space Telescope-Spitzer Light Curves
• JHK Magnitudes for L and T Dwarfs and Infrared Photometric Systems
• A Study of the Diverse T Dwarf Population Revealed by WISE
• T Dwarfs and the Substellar Mass Function. I. Monte Carlo Simulations
• The 2MASS Wide-Field T Dwarf Search. IV Unting out T dwarfs with Methane Imaging
• The First Ultra-Cool Brown Dwarf Discovered by the Wide-field Infrared Survey Explorer
• Two Extraordinary Substellar Binaries at the T/Y Transition and the Y-Band Fluxes of the Coolest Brown Dwarfs
• A Comparison of Near-Infrared Photometry and Spectra for Y Dwarfs with a New Generation of Cool Cloudy Models
• PANIC: A Near-infrared Camera for the Magellan Telescopes
• WISE J163940.83-684738.6: A Y Dwarf identified by Methane Imaging
• Weather on Other Worlds I: Detection of Periodic Variability in the L3 Dwarf DENIS-P J1058.7-1548 with Precise Multi-Wavelength Photometry
• The Coldest Brown Dwarf (Or Free Floating Planet)?: The Y Dwarf WISE 1828+2650
• New M, L, and T Dwarf Companions to Nearby Stars from the Wide-field Infrared Survey Explorer
• Parallaxes and Proper Motions of Ultracool Brown Dwarfs of Spectral Types Y and Late T
• Spitzer Photometry of WISE-Selected Brown Dwarf and Hyper-Luminous Infrared Galaxy Candidates
• The FourStar Infrared Camera
• A search for rocky planets transiting brown dwarfs

Cited by in corpus (32)

• Discovery of a ~250 K Brown Dwarf at 2 pc from the Sun
• Water Clouds in Y Dwarfs and Exoplanets
• The Field Substellar Mass Function Based on the Full-sky 20-pc Census of 525 L, T, and Y Dwarfs
• The 10 parsec sample in the Gaia era
• Preliminary Trigonometric Parallaxes of 184 Late-T and Y Dwarfs and an Analysis of the Field Substellar Mass Function into the "Planetary" Mass Regime
• Hubble Space Telescope Spectroscopy of Brown Dwarfs Discovered with the Wide-field Infrared Survey Explorer
• Atmospheres of 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
• The Luminosities of the Coldest Brown Dwarfs
• Search for free-floating planetary-mass objects in the Pleiades
• Three New Cool Brown Dwarfs Discovered with the Wide-field Infrared Survey Explorer (WISE) and an Improved Spectrum of the Y0 Dwarf WISE J041022.71+150248.4
• Self-consistent Models of Y Dwarf Atmospheres with Water Clouds and Disequilibrium Chemistry
• Indications of Water Clouds in the Coldest Known Brown Dwarf
• The Spectral Energy Distribution of the Coldest Known Brown Dwarf
• High-redshift galaxies and low-mass stars
• Discovery of a new Y dwarf: WISE J030449.03-270508.3
• New Y and T dwarfs from WISE identified by Methane Imaging
• WISEA J083011.95+283716.0: A Missing Link Planetary-Mass Object
• 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
• A New Parallax Measurement for the Coldest Known Brown Dwarf
• Searching for Binary Y dwarfs with the Gemini Multi-Conjugate Adaptive Optics System (GeMS)
• The Collapse of the Wien Tail in the Coldest Brown Dwarf? Hubble Space Telescope Near-Infrared Photometry of WISE J085510.83-071442.5
• Resolved Spectroscopy of the T8.5 and Y0-0.5 Binary WISEPC J121756.91+162640.2AB
• Spectral energy distribution simulations of a possible ring structure around the young, red brown dwarf G196-3B
• Ultracool dwarf benchmarks with \emph{Gaia} primaries
• Near-infrared Detection of WD 0806-661 B with the Hubble Space Telescope
• Measuring High-Precision Astrometry with the Infrared Array Camera on the Spitzer Space Telescope
• The long-term dynamical evolution of disc-fragmented multiple systems in the Solar Neighborhood
• WISEA J064750.85-154616.4: a new nearby L/T transition dwarf
• Probing Late-type T dwarf J-H Color Outliers for Signs of Age
• Ross 19B: An Extremely Cold Companion Discovered via the Backyard Worlds: Planet 9 Citizen Science Project