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2MASS J10475385+2124234
Brown dwarf star in the constellation Leo From Wikipedia, the free encyclopedia
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2MASS J10475385+2124234 (abbreviated to 2MASS J1047+21) is a brown dwarf of spectral class T6.5, in the constellation Leo. This object lies at a distance of 34 light-years from Earth. It first attracted attention by becoming the first brown dwarf of spectral class T from which radio waves were detected. This discovery then permitted its wind speeds to be computed.
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Discovery
2MASS J1047+21 was discovered in 1999 along with eight other brown dwarf candidates during the 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.[7]
Detection of radio emissions
In 2010, astronomers using the Arecibo radio telescope discovered bursts of low-frequency radio waves coming from 2MASS J1047+21. This radio emission comes from electrons spiraling around the magnetic field lines of the brown dwarf.[8][9] Since the frequency of the radio emission is linked to the strength of the magnetic field, the team measured a magnetic field strength of 1.7 kG. The bursts were also found to drift in frequency, in a manner reminiscent of certain types of solar radio emission. The radio emissions, together with the detection of Hα, which is usually found in stellar chromospheres, shows that 2MASS J1047+21 is magnetically active.
Measurement of wind speed
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.[10][11][12][13] The radio emissions are coming from electrons interacting with the magnetic field, which is rooted deep in the interior.[12] The visible and infrared (IR) data, on the other hand, reveal what's happening in the gas giant's cloud tops.[12]
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Characteristics

Radio emissions imply a magnetic field strength greater than 1.7 kG, or approximately 3000 times stronger than the Earth's magnetic field.[14]
Wind speeds

Wind speeds on 2MASS J1047+21 were measured to be 650 ± 310 metres per second (1,450 ± 690 mph) by the Spitzer Space Telescope.[6][15][16]
See also
other T-dwarfs with radio emission:
- SIMP J013656.5+093347.3 T2.5, planetary-mass object
- WISEPC J112254.73+255021.5 T6
- WISEPA J101905.63+652954.2 T5.5+T7.0
- WISEPA J062309.94-045624.6 T8
- 2MASS 1237+6526 T6.5
References
External links
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