Figure 20.
Combination of three
TEXES spectral scans,
with red through
blue, corresponding
to increasing altitude
above Jupiter’s cloud
tops. Note the cool
wake to the left of the
Great Red Spot seen at
lower right (about 15˚
west longitude and -20˚
Latitude).
Credit: L. Fletcher,
University of Leicester, UK
TEXES Returns to Gemini North
TEXES, the visiting high-resolution mid-
infrared spectrograph, returned to Gemini
North in March 2017. This run supported
a wide-ranging set of community science
programs, including the following: summer-
solstice observations of Saturn’s polar vor-
tex; three programs studying Jupiter’s atmo-
sphere and aurora; studies of the chemistry
of the gaps in protoplanetary disks around
other stars; organics in hot star-forming
cores; and the motions of gas in embedded
super star clusters.
One of the science programs, carried out in
collaboration with the TEXES team and Leigh
Fletcher of the University of Leicester in the
UK, involved mid-infrared (8-micron) ob-
servations to explore the meteorology and
chemistry of Jupiter’s dynamic weather layer.
According to Fletcher, to truly understand the
atmospheric phenomena at work in Jupiter,
we must investigate three different domains:
spatial, temporal, and spectral. Past investi-
gations have allowed them to target one of
these domains, but today they are able to ex-
plore all three by combining the Gemini Ob-
servatory, the TEXES spectrograph, and the
worldwide campaign of Earth-based support
for NASA’s Juno mission.
The three-color map shown in Figure 20
reveals Jupiter’s weather layer near 8.6 mi-
crons, where temperature, cloud opacity,
and gaseous species (like deuterated meth-
ane and phosphine) govern Jupiter’s spec-
trum. The researchers constructed the map
from spectral scans over two nights (March
12–13, 2017), and it represents close to the
76
GeminiFocus
highest spatial resolution ever achieved
by the TEXES instrument. At mid-infrared
wavelengths most of the seeing is due to
image motion, which Gemini’s rapid tip-
tilt secondary mirror removes. The result is
diffraction-limited images with 0.3 arcsec-
ond resolution without the use of adap-
tive optics. This easily surpasses the spatial
resolution afforded by past spacecraft flybys
of Jupiter (Voyager and Cassini) in the mid-
infrared wavelength range.
A high-resolution spectrum was measured
for every pixel in this map. The essential in-
formation from the spectra is shown in the
false color image: deep, warm temperatures
at the cloud tops (red); cooler temperatures
at higher altitudes near the tropopause
(blue); and an intermediate altitude (green).
The Equatorial Zone and the Great Red Spot
at the bottom right are cold and dark at all
three wavelengths. The turbulent wake seen
to the west (left) of the Great Red Spot is
darker (cooler) and distinct from the rest of
Jupiter’s South Equatorial Belt (SEB). An out-
break of dark, cold, and cloudy plumes can
be seen in the SEB near 15˚ south, 270˚ west.
Finally, the pattern of cold, cloudy plumes
(dark) and warm, bright hotspots (white)
can be seen encircling the planet near lati-
tude 7˚ north, on the edge of Jupiter’s North
Equatorial Belt. These data will be used to
determine the 3D temperature, aerosol, and
gaseous structure to support Juno’s close-in
observations of the giant planet.
January 2018 / 2017 Year in Review