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The density of the Io plasma torus ribbon
Author(s) -
Küppers Michael,
Schneider Nicholas M.
Publication year - 1998
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/98gl52060
Subject(s) - magnetosphere , physics , plasma , torus , jupiter (rocket family) , radiative transfer , jovian , astrophysics , extreme ultraviolet , astronomy , venus , plasma sheet , atmospheric sciences , planet , computational physics , saturn , astrobiology , optics , spacecraft , laser , geometry , mathematics , quantum mechanics
We investigate two contradictory determinations of the density of the “ribbon” feature within the Io plasma torus. A value of ∼2000 cm −3 was measured by the Voyager 1 Plasma Science and Planetary Radio Astronomy instruments. Volwerk et al. [1997] recently suggested a value at least 5 times higher, and possibly much greater. Their upward revision is based on rapid EUV intensity variations observed by the Voyager Ultraviolet Spectrometers: Short radiative cooling times are only possible with higher plasma densities. We have modeled emissions from both the Voyager‐based torus model and the high‐density case suggested by Volwerk, and show that the latter is inconsistent with the intensity and morphology of numerous observations. We suggest that the observations by Volwerk et al. [1997] can be explained by a closer examination of the radiative cooling process and possibly by short‐term temperature variations caused by variability of the dawn‐dusk electric field in the Jovian magnetosphere.