Jupiter’s polar ionospheric flows: Measured intensity and velocity variations

poleward of the main auroral oval

T. S. Stallard,1,2 S. Miller,1,2 S. W. H. Cowley,3

1Department of Physics and Astronomy, University College London, London, UK.

2Visiting astronomer at the NASA Infrared Telescope Facility,

University of Hawaii Institute for Astronomy, Honolulu, Hawaii, USA.

3Department of Physics and Astronomy, University of

Leicester, Leicester, UK. and E. J. Bunce3.

1

Cowley et al. 2001

2

Cowley and Bunce (2001)

3

Various emissions from Jupiter

4

Rego et al. 1994

Kostiuk et al 19993

H3+ emission from Jupiter

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•H3+ is formed in the jovian ionosphere by the rapid ion-molecule reaction

(H2+ + H2 → H3

+ + H) that follows ionization of molecular H2.

•H3+ is the major ionospheric ion between 1 and 100 bar, with H+ dominating at

higher altitudes.

Connerney and Satoh 2000 (Phil Trans. R. Soc.)

Jupiter’s Northern aurora in infrared

6Satoh et al 1996 (Icarus)

Composite image from several IRTF images from Mona Kea observatory

Stallard et al. 2001, Icarus

7

Stallard et al. 2001, Icarus

8

Stallard et al. 2003

9

10

Stallard et al. 2003

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Conclusions

• The polar region within Jupiter’s main auroral oval ( as seen in infrared emission) appears to consist of three regions, rather than the two previously discussed Bright and Dark Polar Regions.

• Higher latitude velocity profiles show the DPR is stationary in the MPRF.

• Lower latitude DPR velocity profiles show an increasing deviation from a zero velocity with increasing co-latitude.

• The DPR shows much higher levels of H3+ emission than can be produced by solar EUV ionization. Suggests particle precipitation but why?

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