2MASS J10475385+2124234

2MASS J10475385+2124234 (abbreviated to 2MASS J1047+21) is a brown dwarf of spectral class T6.5, in the constellation Leo about 34 light-years from Earth, hence in galactic topographical and interstellar medium study terms being in the Local Bubble and very nearby in the Orion Arm. It is the first brown dwarf to have an inferred range of its typical wind speeds computed.

Discovery
2MASS J1047+21 was discovered in 1999 along with eight other brown dwarf candidates by Adam J. Burgasser et al. from Two Micron All-Sky Survey (2MASS), conducted from 1997 to 2001. Follow-up observations with the Keck I 10-meter telescope's Near Infrared Camera (NIRC) were conducted on 27 May 1999 and identified methane in 2MASS J1047+21's near-infrared spectrum, classifying it as a T-type brown dwarf.

Methodology
The wind speed is directly inferred from minute, regular cycles in its visible (which matches its ultra-violet) appearance compared to the same at radio wave spectra. The radio emissions are coming from electrons interacting with the magnetic field, which is rooted deep in the interior. The visible and infrared (IR) data, on the other hand, reveal what's happening in the gas giant's cloud tops.

Distance
2MASS J1047+21 is about 34 ly from Earth.

Characteristics
2MASS J1047+21 is a T-type brown dwarf.

Wind speeds
Wind speeds on 2MASS J1047+21 were measured to be 650 ± 310 m/s by the Spitzer Space Telescope.

Magnetic Field
A pulse at 15–16.5 GHz was also detected for the T6.5 dwarf 2MASS 10475385 +2124234, corresponding to a localized 5.6 kG field strength. For the same object, a 16.5–18 GHz pulse was tentatively detected, corresponding to a localized 6.2 kG field strength. Rapid rotation may be important for producing strong dipole fields in convective dynamos. Rapid rotation is a key ingredient for driving the current systems powering auroral radio emission. The authors observe evidence of variable structure in the frequency-dependent time series of targets on timescales shorter than a rotation period, suggesting a higher degree of variability in the current systems near the surfaces of brown dwarfs. Age, mass, and temperature together cannot account for the strong magnetic fields produced. This makes it the brown dwarf with the strongest magnetic field.