Leicester astronomer leads study of observations of Jupiter in the far-infrared

Dr Leigh Fletcher from our Department of Physics and Astronomy has lead a team that has produced far-infrared maps of Jupiter for the first time since the twin Voyager spacecraft missions in 1979 using NASA’s Stratospheric Observatory for Infrared Astronomy, SOFIA.

These maps allow researchers to study the circulation of gases within the gas giant planet’s atmosphere. The team was looking for the two types of molecular hydrogen, called “para” and “ortho” – differentiated by whether their protons have aligned or opposite spins. The fraction of hydrogen in the “para” flavour is a good indicator for gases upwelling from deep within the planet’s atmosphere. These two different flavours of hydrogen were observed at infrared wavelengths between 17 and 37 microns, a spectral range that is largely inaccessible to ground-based telescopes.

Images from SOFIA reveal several interesting features. The Great Red Spot appears as a large, cold feature in the southern hemisphere, indicating an upwelling of gas. The belt zone structure near the equator shows that the equator is cold and surrounded by warm belts of sinking gas. Bright, warm features near the north pole reveals the heating of the planet’s upper atmosphere by the powerful aurora.

SOFIA’s unique observations of the comparison between ortho and para hydrogen reveal a gradual trend from the equatorial to polar regions.  Dr Fletcher’s research team found that significant upward mixing at low latitudes was responsible for the presence of “para-hydrogen” in the tropics, whereas the atmosphere appeared more sluggish at high latitudes.  Downwelling over the poles may be further affecting the distribution of para-hydrogen, but further observations from SOFIA are necessary to better understand the processes over time. The results from Dr Fletcher's team’s observations were recently published in the journal Icarus.