Observations with the National Science Foundation's Very Large Array
(VLA) have given scientists an unprecedented look into the atmosphere of
Jupiter, revealing that features seen in visible light at the planet's
cloud surfaces have effects tens of kilometers downward.
The
scientists used the VLA to study the dynamics of Jupiter's atmosphere
from the visible cloud surfaces down to about 100 kilometers below the
clouds.
"This region was previously unexplored," said Imke de
Pater, of the University of California, Berkeley. "These observations
give us important new information about the temperatures, pressures, and
motions of gas at these levels of the atmosphere," she added.
The
new images provide detail that was unavailable before. In order to make
sensitive radio images, multi-antenna telescopes such as the VLA must
gather the radio waves emitted by an object for a significant amount of
time, like a time exposure in a camera. However, Jupiter rotates so
swiftly, with a "day" of less than 10 hours, that a conventional radio
image would be smeared in just a few minutes.
To overcome this
obstacle, the researchers took advantage of the added sensitivity of the
upgraded VLA, then developed an innovative data-reduction technique to
"unsmear" the data from many hours of observing. The results showed a
level of detail that provided new insights into the structure and
dynamics of the giant planet's atmosphere.
"We were able to make
maps of Jupiter as seen at different radio wavelengths, then compare
these to visible-light images made at nearly the same times," said Bryan
Butler, of the National Radio Astronomy Observatory.
Jupiter's
familar light-colored zones and darker belts, visible even through small
telescopes, were thought to be well-correlated to radio features, but
the new radio images showed some similar structures unconnected to
visible-light features. The radio images showed evidence of what the
scientists think are rising plumes of gas that are part of the wave
pattern that produces "hot spots' in the planet's atmosphere.
The
Great Red Spot, perhaps the most famous feature on Jupiter, is also
prominent, along with similar, smaller storms, in the radio images.
The
new data allowed the scientists to construct graphs showing the
concentrations of ammonia, an important constituent of Jupiter's
atmosphere, as it changes with altitude.
"All told, there is a
wealth of information about the structure of Jupiter's atmosphere in
these new VLA images," de Pater said. "We hope to resolve a number of
outstanding questions with these and future studies using similar
techniques," she added.
Butler and de Pater worked with Robert
Sault of the University of Melbourne, Australia, and David DeBoer and
Michael Wong, of the University of California, Berkeley. The astronomers
are reporting their results in the 3 June edition of the journal Science.
The
National Radio Astronomy Observatory is a facility of the National
Science Foundation, operated under cooperative agreement by Associated
Universities, Inc.
Contact:
Dave Finley, Public Information Officer
(575) 835-7302
dfinley@nrao.edu
