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Brown Dwarfs
The flare observed by Chandra from LP944-20 could have its origin in the
turbulent magnetized hot material beneath the brown dwarf's surface. A
sub-surface flare could conduct heat to the atmosphere, allowing electric currents to flow and produce
an X-ray flare, like a stroke of lightning. Further observations of brown dwarf
flares will be very important for understanding the development of strong
magnetic fields and flaring activity in brown dwarfs and giant planets.
Chandra image of LP 944-20 before
flare and during flare.
(NASA/UCB/Caltech/R.Rutledge et al.) |
The absence of X-rays from LP 944-20 during the non flaring period is also a
significant result. It sets the lowest observational limit on steady X-ray power
produced by a brown dwarf star, and shows that million degree Celsius upper
atmospheres, or coronas, cease to exist
as the surface temperature of a brown dwarf cools below about 2500 degrees
Celsius and becomes electrically neutral.
For more information on the discovery of brown dwarfs see:
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