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

TL;DR

This paper characterizes 2MASS J11151597+1937266 as a young, dusty, isolated planetary-mass object with potential wide stellar companionship, based on spectral analysis, infrared excess, and kinematic data, suggesting it is a rare free-floating planetary-mass object.

Contribution

It provides detailed spectral, photometric, and kinematic analysis of a young, dusty planetary-mass object and identifies a potential wide stellar companion, expanding understanding of isolated planetary-mass objects.

Findings

Confirmed low-surface gravity L2γ spectral type.

Estimated mass between 7-21 Jupiter masses.

Identified a candidate co-moving 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$_{\mathrm{H}\alpha}=560\pm82$ \AA) 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.