* Astronomy

Title: 2MASSJ035523.51+113337.4: A Young, Dusty, Nearby, Isolated Brown Dwarf Resembling A Giant Exoplanet
Authors: Jacqueline K. Faherty (Universidad de Chile, Cerro Calan, AMNH), Emily L. Rice (College of Staten Island, CUNY, AMNH), Kelle L. Cruz (Hunter College, CUNY, AMNH), Eric E. Mamajek (CTIO), Alejandro Núñez (Hunter College, CUNY, AMNH)

We present parallax and proper motion measurements, near-infrared spectra, and WISE photometry for the low surface gravity L5gamma dwarf 2MASSJ035523.51+113337.4 (2M0355). We use these data to evaluate photometric, spectral, and kinematic signatures of youth. We confirm low-gravity spectral morphology and find a strong resemblance to the sharp triangular shaped H-band spectrum of the ~10 Myr planetary-mass object 2MASSJ1207b. We find that 2M0355 is underluminous compared to a normal field L5 dwarf in the optical and MKO J,H, and K bands and transitions to being overluminous from 3-12 microns indicating that enhanced photospheric dust shifts flux to longer wavelengths for young, low-gravity objects, creating a red spectral energy distribution. Investigating the near-infrared colour magnitude diagram for brown dwarfs confirms that 2M0355 is redder and underluminous compared to the known brown dwarf population, similar to the peculiarities of directly imaged exoplanets 2MASSJ1207b and HR8799bcd. We calculate UVW space velocities and find that while the motion of 2M0355 is consistent with young disk objects (< 2-3 Gyr) we can not confirm its association with the youngest nearby associations (e.g. Beta Pictoris, AB Doradus, TW Hydrae). The birthplace, current moving group membership, and constrained age (hence mass) for 2M0355 remain unknown.

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