Flaring up All Over—Radio Activity in Rapidly Rotating Late M and L Dwarfs

摘要: We present Very Large Array observations of 12 late M and L dwarfs in the solar neighborhood. The observed sources were chosen to cover a wide range physical characteristics—spectral type, rotation, age, binarity, X-ray Hα activity—to determine role these properties production radio emission hence magnetic fields. Three sources, TVLM 513-46546, 2MASS J0036159+182110, BRI 0021-0214, flare also exhibit persistent emission, indicating that activity is not quenched at bottom main sequence. extends spectral type L3.5, there no apparent decrease ratio flaring luminosities bolometric between M8 L3.5. Moreover, contrary significant drop beyond M7, appears steadily increase M3 Similarly, from 0021-0214 violates phenomenological relations coronally active stars, hinting are uncorrelated sequence; an even stronger violation was found for brown dwarf LP 944-20. radio-active have measured rotational velocities rapid rotators, v sin i > 30 km s-1, while upper limits on slowly rotating (v < 10 s-1) this survey literature lower than detections. These provide tantalizing evidence rapidly more likely be active. This possible correlation puzzling given requires sustained fields ~10-103 G densities ~1012 cm-3, should slowed down considerably as result braking.