Hyperactive brown dwarf has a companion, and may be old and heavy to boot

Stellar activity is typically attributed to magnetic field interactions, but in brown dwarfs this emission is more of a mystery.

For the most part, brown dwarfs don’t do very much; they just sit there and slowly cool off.  But a rare few are “hyperactive”, exhibiting emission lines that both vary and persist over long periods of time. The source of this activity has been a mystery for nearly a decade, but new observations we’ve conducted with the IRTF, Magellan and Keck Telescopes show that one of these hyperactive dwarfs has a very faint companion, and that it is hyperactive because it is very old and relatively massive.

First L Dwarf in the Kepler Field

An image of WISE 1906+4011 from the Kepler Observatory; the green mask marks the location of this faint source.

The Kepler Observatory is uncovering numerous planets in close orbits around distant stars.  Now it has a brown dwarf under its belt.  A search for nearby cool dwarfs by University of Delaware collaborator John Gizis uncovered the first L dwarf in Kepler, a source that may teach us much about clouds in cool brown dwarfs.