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arXiv · 1712.03964

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

Christopher A. Theissen·Adam J. Burgasser·Daniella C. Bardalez Gagliuffi·Kevin K. Hardegree-Ullman·Jonathan Gagné·Sarah J. Schmidt·Andrew A. West
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Abstract

We present 2MASS J11151597+1937266, a recently identified low-surface gravity L dwarf, classified as an L2$γ$ 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$α$ emission (EW$_{\mathrm{H}α}=560\pm82$ 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 $1724^{+184}_{-38}$ K. We also provide a revised distance estimate of $37\pm6$ 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.

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Christopher A. Theissen, Adam J. Burgasser, Daniella C. Bardalez Gagliuffi, Kevin K. Hardegree-Ullman, Jonathan Gagné, Sarah J. Schmidt, Andrew A. West. 2017-12-13. 2MASS J11151597+1937266: A Young, Dusty, Isolated, Planetary-Mass Object with a Potential Wide Stellar Companion. https://doi.org/10.3847/1538-4357%2Faaa0cf

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