Nancy A. Levenson
Figure 1.
Gemini spectrum
of W1906+40, in
its quiescent state
(black) and during
a strong flare (blue).
In addition to the
overall increase in
luminosity, the Ha
emission appears
broad and the
overall spectral
shape corresponds to
higher temperatures
during the flare.
(The spectra are
not corrected for
the effects of Earth’s
atmosphere.)
Science Highlights
Recent reports on the most powerful flare ever observed on
an L dwarf, spiral patterns in a protoplanetary disk, and the
properties of galaxies in intermediate-mass clusters.
The Most Powerful Flare ever Observed on an L Dwarf
Astronomers used the Gemini Multi-Object Spectrograph on Gemini North to capture the
most powerful flare ever observed on an L dwarf. At its peak, the brightness of the Jupitersized source increased by a factor of three, with a total flare energy output of 1.6 x 1032 ergs.
The team suggests that similar flares may be common in this class of substellar objects, occurring once or twice per month. The Gemini data also provided the L1 spectral type of the
brown dwarf, named WISE J190648.47+401106.8 for its discovery using NASA’s WISE satellite, or W1906+40 for short.
John Gizis (University
of Delaware) and collaborators have been
observing W1906+40
using the Kepler satellite and a variety
of ground-based facilities. The long-term
(15-month) monitoring with Kepler shows
a regular brightness
variation at the 1
percent level with a
period of 8.9 hours.
The team models
this variability as the
presence of a single
“spot” of lower-than-
12
GeminiFocus
January2014