2MASS J11151597+1937266: A Young, Dusty, Isolated, Planetary-Mass Object with a Potential Wide Stellar Companion

Abstract

We present 2MASS J11151597+1937266, a recently identified low-surface gravity L dwarf, classified as an L2$\gamma$ based on Sloan Digital Sky Survey optical spectroscopy. We confirm this spectral type with near-infrared spectroscopy, which provides further evidence that 2MASS J11151597+1937266 is a low-surface gravity L dwarf. This object also shows significant excess mid-infrared flux, indicative of circumstellar material; and its strong H$\alpha$ emission (EW${}_{\mathrm{H}\alpha }=560\pm 82$ Å) is an indicator of enhanced magnetic activity or weak accretion. Comparison of its spectral energy distribution to model photospheres yields an effective temperature of $1724_{-38}^{+184}$ K. We also provide a revised distance estimate of $37\pm 6$ pc using a spectral type-luminosity relationship for low-surface gravity objects. The 3-dimensional galactic velocities and positions of 2MASS J11151597+1937266 do not match any known young association or moving group. Assuming a probable age in the range of 5-45 Myr, the model-dependent estimated mass of this object is between 7-21 $M_{\mathrm{Jup}}$, making it a potentially isolated planetary-mass object. We also identify a candidate co-moving, young stellar companion, 2MASS J11131089+2110086.

Accepted to ApJ

References in corpus (19)

• Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties
• New evolutionary models for pre-main sequence and main sequence low-mass stars down to the hydrogen-burning limit
• The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
• 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
• Population Properties of Brown Dwarf Analogs to Exoplanets
• A Stellar Census of the Tucana-Horologium Moving Group
• Comoving stars in Gaia DR1: An abundance of very wide separation co-moving pairs
• 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?
• Meeting the Cool Neighbors X: Ultracool dwarfs from the 2MASS All-Sky Data Release
• LACEwING: A New Moving Group Analysis Code
• Surface Gravities for 228 M, L, and T Dwarfs in the NIRSPEC Brown Dwarf Spectroscopic Survey
• WISE J072003.20-084651.2: An Old and Active M9.5 + T5 Spectral Binary 6 pc from the Sun
• BANYAN. VIII. New Low-Mass Stars and Brown Dwarfs with Candidate Circumstellar Disks
• Gaia Assorted Mass Binaries Long Excluded from SLoWPoKES (GAMBLES): Identifying Ultra-Wide Binary Pairs with Components of Diverse Mass
• A survey for planetary-mass brown dwarfs in the Chamaeleon I star-forming region
• The Late-Type Extension to MoVeRS (LaTE-MoVeRS): Proper motion verified low-mass stars and brown dwarfs from SDSS, 2MASS, and WISE
• Collisions of Terrestrial Worlds: The Occurrence of Extreme Mid-Infrared Excesses around Low-Mass Field Stars

Cited by in corpus (6)

• Revisiting the Helium and Hydrogen Accretion Indicators at TWA 27B: Weak Mass Flow at Near-Freefall Velocity
• Substellar and low-mass dwarf identification with near-infrared imaging space observatories
• The puzzle of the formation of T8 dwarf Ross 458c
• Exoplanet accretion monitoring spectroscopic survey (ENTROPY) I. Evidence for magnetospheric accretion in the young isolated planetary-mass object 2MASS J11151597+1937266
• Strong H$\alpha$ emission in the young planetary mass companion 2MASS J0249-0557 c
• Occurrence rates of accreting companions from a new method for computing emission-line survey sensitivity: application to the H-alpha Giant Accreting Protoplanet Survey