Jupiter

This 4-panel photograph (click to enlarge image) shows longitude-averaged images of Jupiter at wavelengths of 2, 3.5 and 6 cm; the latter image shows the total emission (thermal + nonthermal), as well as an image where the nonthermal (synchrotron) radiation was subtracted. These images were taken close in time with the Galileo probe entry into Jupiter's atmosphere, Dec. 7, 1995. (Ref: de Pater, I., D. Dunn, K. Zahnle and P.N. Romani, 2001. Comparison of Galileo Probe Data with Ground-based Radio Measurements. Icarus, vol. 149, 66-78.

The image at left is a radio image of Jupiter at 2cm, derived from VLA observations taken on 25 January 1996. The data were taken by Imke de Pater (UC Berkeley), and were further reduced and imaged by Chermelle Engel (University of Melbourne) and Bob Sault (ATNF). (Sault, R.J., C. Engel, and I. de Pater, 2002. Topographic imaging of Jupiter at radio wavelengths. Icarus, submitted.)

SL9 (6 panel image) The impact of comet Shoemaker-Levy 9 with Jupiter in July 1994 drastically changed the radiation characteristics of Jupiter's synchrotron radiation. The observations can largely be explained using a model of enhanced radial diffusion of the radiating electrons, as well as a direct acceleration of the electrons by the upward propagating shock. This image shows data (panels a and b) and models (panels c-f). For details see Brecht, S.H., I. de Pater, D.J. Larson, and M.E. Pesses, 2000. Modification of the Jovian radiation Belts by Shoemaker-Levy 9: An Explanation of the Data. Icarus, vol. 151, 25-38.

Energetic electrons trapped in Jupiter's magnetic field emit synchrotron radiation. The image at left (click to enlarge image) is a false-color image of this emission, at a Jovian longitude of 312 degrees. The data were obtained with the Very Large Array at a wavelength of 20 cm. We overplotted magnetic field lines at an equatorial `distance' of 1.5 and 2.5 Jovian radii (from Jupiter's center) (from Jack Connerney's O6 magnetic model). (Ref: de Pater, I., M. Schulz, and S.H. Brecht, 1997. Synchrotron evidence for Amalthea's influence on Jupiter's electron radiation belt. J. Geoph. Res., vol. 102, pp. 22,043 - 22,064)

Three-dimensional tomographic reconstruction of Jupiter's nonthermal radio emissivity. We used R.J. Sault's 3D Fast Fourier Transform algorithm on the VLA data shown at left, and R. E. Gooch's visualization software package for displaying and making movies (click to view enlarged image plus movie). (Ref: de Pater and Sault, 1998. An intercomparison of 3-D reconstruction techniques using data and models of Jupiter's synchrotron radiation. J. Geophys. Res. vol. 103, pp. 19,973-19,984)

Saturn

Saturn observed at a wavelength of 3.5 cm with the VLA on Sep. 1, 1990. Note the brighter (hotter) bands on Saturn, similar in appearance to Jupiter's banded structure. The three main rings, A, B, and C ring, including the Cassini Division can be distinguished in the image. There is a general East-West asymmetry, in that the West ansa is brighter, as perhaps caused by 'wakes' or gravitational clumping in the rings. The white contours represent the linearly polarized flux density, showing that scattered light from Saturn's rings is lightly polarized. (Ref: Van der Tak, F., I. de Pater, A. Silva and R. Millan, 1999. Variability of Saturn's brightness distribution, Icarus, vol. 142, pp. 125-147.)

Comets

Our group is involved in imaging OH (maser) emission from comets using the VLA, and the thermal emission from molecules such as HCN, CS and the H2CO-ion with BIMA. Examples are shown of an OH image from comet Halley (taken with the VLA in Nov. 1985)[upper thumbnail], and an HCN spectrum [middle thumbnail] and dust emission image [lower thumbnail] from comet Hale-Bopp (taken in March 1997 with BIMA).

(Refs: de Pater, I., P. Palmer, and L.E. Snyder, 1986, the brightness distribution of OH around comet Halley, Astrophys. J. Lett., vol. 304, pp. L33-L36. de Pater, I., J.R. Forster, M. Wright, B. J. Butler, P. Palmer, J. M. Veal, M. F. A'Hearn, and L. E. Snyder, 1998, BIMA and VLA observations of Comet Hale-Bopp at 22 -- 115 GHz, Astron. J., vol. 116, pp. 987-996. Wright, M.C.H., I. de Pater, J. R. Forster, P. Palmer, L.E. Snyder, J.M. Veal M.F. A'Hearn, L.M. Woodney, W.M. Jackson, Y.-J. Kuan, and A.J. Lovell, 1998. Mosaiced Images and Spectra of J=1-->0 HCN and HCO+ emission from Comet Hale-Bopp (1995 O1). Astron. J., vol. 116, pp. 3018-3028.)