Longitude-resolved VLA Radio Maps of Jupiter

Wed, May 06, 2015

Visible light and 5-micron infrared images of Jupiter reveal the familiar zone-belt structure, where the brown belts appear as warm regions at 5 μm. As clouds are a major source of opacity at this wavelength, the high 5 μm temperatures are indicative of no or relatively thin cloud decks so that deeper warmer layers are probed. In the mid-eighties microwave images at 1 – 6 cm showed a similar zone-belt structure, where deeper warmer layers were probed in the belts, due to a lower NH3 abundance in the belts than in the zones. Conventional radio interferometric images are integrated over many hours to meet the required sensitivity and to use Earth rotation synthesis to achieve good sampling of the Fourier plane. Consequently, any potential structure in longitude is smeared out in such maps. In 2004, we published an innovative technique to synthesize together many hours of radio data to produce a longitude-resolved map [1]. This map showed the hot spots on Jupiter very clearly, and we showed that the NH3 gas abundance must be depleted significantly down to several bars in these hot spots.

This past year we embarked on a program to map Jupiter at multiple wavelengths with the much-improved (order of magnitude in sensitivity) VLA. In this talk we will present our first maps of Jupiter in the  X (3.6 cm) and Ku (2 cm) bands. These maps will be compared with maps produced by the amateur community at optical wavelengths, with similar resolution, and radiative transfer calculations of a select number of features will be presented.

[1] Sault, R.J., C. Engel, and I. de Pater, 2004. Longitude-resolved Imaging of Jupiter at  l=2 cm. Icarus, 168, 336-343.