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.

Clouds on a Young Planet: First Science Results with FIRE

A UKIDSS false color image of the Ross 458 system, composed of a pair of M dwarfs (bright star in upper left corner) and the planetary-mass brown dwarf Ross 458C (circled in lower right corner).

To study the atmospheres of young planets outside our Solar System, we need not look  far.  The first brown dwarf science with the newly-commissioned FIRE spectrograph has revealed the presence of rock clouds in the atmosphere of a planetary-mass companion to the nearby Ross 458 system.  The presence of these clouds, and the planetary nature of the source, defy prior expectations.

The source in question is Ross 458C, a brown dwarf candidate identified in the UKIDSS survey in early 2010 by two independent studies led by Drs. Rolf-Dieter Scholz and Betrand Goldman.  This source, also known as ULAS J130041.72+122114.7, is located 1.7′ (0.028 degrees) southeast of the Ross 458 system, a pair of magnetically active M dwarfs only 11.2 pc (36.5 light-years) from the Sun. The colors and faintness of Ross 458C, and that fact that it co-moves with the Ross 458 system, led both studies to conclude that it was potentially a very cool and very low-mass brown dwarf companion.  However, neither study had the necessary spectral data to probe its atmosphere.

FIRE is alive!

FIRE mounted on Magellan's Baade Telescope

The Folded Port Infrared Echellette was successfully delivered and commissioned at the Magellan Telescopes at Las Campanas Observatory in Chile. Led by MIT Asst. Professor Robert Simcoe and Adam Burgasser, with major contributions by postdoctoral researcher John Bochanski, FIRE is a single-object, near-infrared spectrograph capable of obtaining 0.9-2.5 μm spectroscopy of faint sources at resolutions of 300-10,000. First science results will be published later this year.

Learn more at the FIRE website and on a recent blog post.  You can even buy FIRE merchandise!.

April 2010