We present the discovery of VHS J183135.58-551355.9, an L/T transition dwarf identified as a result of its unusually red near-infrared colors (J-K_S_=3.633+/-0.277mag; J-W2=6.249+/-0.245mag) from the VISTA Hemisphere Survey and CatWISE2020 surveys. We obtain low-resolution near-infrared spectroscopy of VHS J1831-5513 using the Magellan Folded port InfraRed Echellette spectrograph to confirm its extremely red nature and assess features sensitive to surface gravity (i.e., youth). Its near-infrared spectrum shows multiple CH4 absorption features, indicating an exceptionally low effective temperature for its spectral type. Based on proper-motion measurements from CatWISE2020 and a photometric distance derived from its Ks-band magnitude, we find that VHS J1831-5513 is a likely (~85% probability) kinematic member of the {beta} Pictoris moving group. Future radial velocity and trigonometric parallax measurements will clarify such membership. Follow-up mid-infrared or higher-resolution near-infrared spectroscopy of this object will allow for further investigation as to the cause(s) of its redness, such as youth, clouds, and viewing geometry.

Cone search capability for table J/AJ/168/66/table1 (Properties of VHS J1831-5513)