WISE2150-7520AB: A very low mass, wide co-moving brown dwarf system discovered through the citizen science project Backyard Worlds: Planet 9

Abstract

We report the discovery of WISE2150-7520AB (W2150AB): a widely separated (~ 341 AU) very low mass L1 + T8 co-moving system. The system consists of the previously known L1 primary 2MASS J21501592-7520367 and a newly discovered T8 secondary found at position 21:50:18.99 -75:20:54.6 (MJD=57947) using Wide-field Infrared Survey Explorer (WISE) data via the Backyard Worlds: Planet 9 citizen science project. We present Spitzer ch1 and ch2 photometry (ch1-ch2= 1.41 +/-0.04 mag) of the secondary and FIRE prism spectra of both components. The sources show no peculiar spectral or photometric signatures indicating that each component is likely field age. Using all observed data and the Gaia DR2 parallax of 41.3593 +/- 0.2799 mas for W2150A we deduce fundamental parameters of log(Lbol/Lsun)=-3.69 +/- 0.01, Teff=2118 +/- 62 K, and an estimated mass=72 +/- 12 MJup for the L1 and log(Lbol/Lsun)=-5.64 +/- 0.02, Teff=719 +/- 61 K, and an estimated mass=34 +/- 22 MJup for the T8. At a physical separation of ~341 AU this system has Ebin = 10^41 erg making it the lowest binding energy system of any pair with Mtot < 0.1 Msun not associated with a young cluster. It is equivalent in estimated mass ratio, Ebin, and physical separation to the ~ 2 Myr M7.25 + M8.25 binary brown dwarf 2MASS J11011926-7732383AB (2M1101AB) found in the Chameleon star forming region. W2150AB is the widest companion system yet observed in the field where the primary is an L dwarf or later.

ApJ accepted October 2019. 18 pages, 8 Figures, two tables. All tabular data is available on a viewable/commentable google sheet here: https://docs.google.com/spreadsheets/d/1bG6BZl7wAus9JRjb_zNVP0PwpBUqpH_IG_daPxWi024/edit?usp=sharing

References in corpus (39)

• The Gaia mission
• Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
• Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics
• The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
• The unWISE Catalog: Two Billion Infrared Sources from Five Years of WISE Imaging
• unWISE: unblurred coadds of the WISE imaging
• Young L Dwarfs Identified in the Field: A Preliminary Low-Gravity, Optical Spectral Sequence from L0 to L5
• The Hawaii Infrared Parallax Program. II. Young Ultracool Field Dwarfs
• Hubble Space Telescope NICMOS Observations of T Dwarfs: Brown Dwarf Multiplicity and New Probes of the L/T Transition
• Discovery of a ~250 K Brown Dwarf at 2 pc from the Sun
• Subtle Signatures of Multiplicity in Late-type Dwarf Spectra: The Unresolved M8.5 + T5 Binary 2MASS J03202839-0446358
• Discovery of a young planetary mass companion to the nearby M dwarf VHS J125601.92-125723.9
• A search for binary systems among the nearest L dwarfs
• SpeX Spectroscopy of Unresolved Very Low Mass Binaries. II. Identification of Fourteen Candidate Binaries with Late-M/Early-L and T Dwarf Components
• The Wide Brown Dwarf Binary Oph 1622-2405 and Discovery of A Wide, Low Mass Binary in Ophiuchus (Oph 1623-2402): A New Class of Young Evaporating Wide Binaries?
• Discovery of a wide planetary-mass companion to the young M3 star GU Psc
• The discovery of an M4+T8.5 binary system
• Discovery of a wide companion near the deuterium burning mass limit in the Upper Scorpius association
• Discovery of a T Dwarf Binary with the Largest Known J-Band Flux Reversal
• Deep Full-sky Coadds from Three Years of WISE and NEOWISE Observations
• A large spectroscopic sample of L and T dwarfs from UKIDSS LAS: peculiar objects, binaries, and space density
• Wide, Cool and Ultracool Companions to Nearby Stars from Pan-STARRS1
• Multiplicity and Optical Excess Across the Substellar Boundary in Taurus
• The Luminosities of the Coldest Brown Dwarfs
• New, nearby bright southern ultracool dwarfs
• Discovery of a Wide Substellar Companion to a Nearby Low-Mass Star
• Southern wide very low-mass stars and brown dwarfs in resolved binary and multiple systems
• SDSS J080531.84+481233.0: An Unresolved L Dwarf/T Dwarf Binary
• Brown dwarf formation by binary disruption
• WISE J072003.20-084651.2: An Old and Active M9.5 + T5 Spectral Binary 6 pc from the Sun
• Five new very low mass binaries
• The multiplicity of planet host stars - New low-mass companions to planet host stars
• Discovery of a 66 mas Ultracool Binary with Laser Guide Star Adaptive Optics
• Trigonometric Parallaxes for Two Late-Type Subdwarfs: LSR1425+71 (sdM8.0) and the Binary LSR1610-00 (sd?M6pec)
• A 3 Gyr White Dwarf with Warm Dust Discovered via the Backyard Worlds: Planet 9 Citizen Science Project
• Individual, Model-Independent Masses of the Closest Known Brown Dwarf Binary to the Sun
• The dynamical evolution of low-mass hydrogen-burning stars, brown dwarfs and planetary-mass objects formed through disc fragmentation
• Proper motions of field L and T dwarfs -II
• Radial Velocities, Space Motions, and Nearby Young Moving Group Memberships of Eleven Candidate Young Brown Dwarfs

Cited by in corpus (18)

• Spitzer Follow-up of Extremely Cold Brown Dwarfs Discovered by the Backyard Worlds: Planet 9 Citizen Science Project
• Self-consistent Models of Y Dwarf Atmospheres with Water Clouds and Disequilibrium Chemistry
• New Candidate Extreme T Subdwarfs from the Backyard Worlds: Planet 9 Citizen Science Project
• WISEA J041451.67-585456.7 and WISEA J181006.18-101000.5: The First Extreme T-type Subdwarfs?
• The Hawaii Infrared Parallax Program. V. New T-Dwarf Members and Candidate Members of Nearby Young Moving Groups
• Uniform Forward-Modeling Analysis of Ultracool Dwarfs. I. Methodology and Benchmarking
• WISEA J083011.95+283716.0: A Missing Link Planetary-Mass Object
• An Atmospheric Retrieval of the Brown Dwarf Gliese 229B
• A Wide Planetary Mass Companion Discovered Through the Citizen Science Project Backyard Worlds: Planet 9
• A wide planetary-mass companion to a young low-mass brown dwarf in Ophiuchus
• Binary Formation in the Orion Nebula Cluster: Exploring the Sub-stellar Limit
• CWISE J014611.20-050850.0AB: The Widest Known Brown Dwarf Binary in the Field
• A Novel Survey for Young Substellar Objects with the W-band filter III: Searching for very low mass brown dwarfs in Serpens South and Serpens Core
• Investigating Possible Binarity for GJ 229B
• NICMOS Kernel-Phase Interferometry II: Demographics of Nearby Brown Dwarfs
• Discovery of a Mid-L Dwarf Companion to the L 262-74 System
• Ross 19B: An Extremely Cold Companion Discovered via the Backyard Worlds: Planet 9 Citizen Science Project
• Discovery of 34 low-mass comoving systems using NOIRLab Source Catalog DR2