Brown dwarfs are classified as objects which are not massive enough to sustain nuclear fusion of hydrogen, and are distinguished from planets by their ability to burn deuterium. 1 Old (>10 Myr) brown dwarfs are expected to possess short-lived magnetic fields 2 and, since they no longer generate energy from collapse and accretion, weak radio and X-ray emitting coronae. Several efforts have been undertaken in the past to detect chromospheric activity from the brown dwarf LP944−20 at X-ray 1,3 and optical 4,5,6,7 wavelengths, but only recently an X-ray flare from this object was detected. 3 Here we report on the discovery of quiescent and flaring radio emission from this source, which represents the first detection of persistent radio emission from a brown dwarf, with luminosities that are several orders of magnitude larger than predicted from an empirical relation 8,9 between the X-ray and radio luminosities of many stellar types. We show in the context of synchrotron emission, that LP944−20 possesses an unusually weak magnetic field in comparison to active dwarf M stars, 10,11 which might explain the null results from previous optical and X-ray observations of this source, and the deviation from the empirical relations. This paper has been submitted to Nature. You are free to use the results here for the purpose of

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The 6 cm formaldehyde (H 2 CO) maser sources in the compact H ii regions NGC 7538 IRS 1 and G29.96À0.02 have been imaged at high resolution ( beam < 50 mas). Using the Very Long Baseline Array and MERLIN, we find the angular sizes of the NGC 7538 masers to be $10 mas (30 AU), corresponding to brightness temperatures $10 8 K. The angular sizes of the G29.96À0.02 masers are $20 mas (130 AU), corresponding to brightness temperatures $10 7 K. Using the VLA, we detect 2 cm formaldehyde absorption from the maser regions. We detect no emission in the 2 cm line, indicating the lack of a 2 cm maser and placing limits on the 6 cm excitation process. We find that both NGC 7538 maser components show an increase in intensity on 5-10 yr timescales while the G29.96À0.02 masers show no variability over 2 yr. A search for polarization provides 3 upper limits of 1% circularly polarized and 10% linearly polarized emission in NGC 7538 and of 15% circularly polarized emission in G29.96À0.02. A pronounced velocity gradient of 28 km s À1 arcsec À1 (1900 km s À1 pc À1 ) is detected in the NGC 7538 maser gas.