Disentangling Electron Temperature and Density in the Io Plasma Torus

Details Disentangling Electron Temperature and Density in the Io Plasma Torus Disentangling Electron Temperature and Density in the Io Plasma Torus

Jul 1997

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1997dps....29.1810h&link_type=abstract

American Astronomical Society, DPS meeting #29, #18.10; Bulletin of the American Astronomical Society, Vol. 29, p.1003

Astronomy and Astrophysics

Astronomy

Scientific paper

% \def\Rj {R\dn J} One of the torus characteristics of most interest for understanding torus energization is its electron temperature (T_e). Yet deriving T_e has always been difficult because the measured quantity (emission brightness) is controlled jointly by T_e and a second unknown, electron density. In order to solve this problem, we have used a new technique to estimate T_e from spectral images of the Io plasma torus in the 350 to 700 AA region obtained by the Extreme Ultraviolet Explorer (EUVE). Because of the lack of information available on the collision strengths of important lines between 350 and 600 AA, we have attempted to simultaneously deduce both the unknown collision strengths and also the time-varying torus characteristics by fitting analytic models which exploit the both the commonalities and the variations among the observations. However, because of present limitations of the method, we can only deduce relative variations in torus T_e, total electron number (N_e -- a proxy for total torus mass), and ionic composition. In the 1993 - 1995 data set, T_e and N_e were strongly anti-correlated, while total torus luminosity remained steadier than either T_e or N_e. The anti-correlation of N_e and T_e suggests that torus luminosity may be primarily determined by a relatively constant power-limited energy supply, so that as N_e increases (decreases), T_e sags (surges) in response. A corollary to this hypothesis would be that the mass loading rate is only weakly coupled to torus energization, contradicting the class of plasma torus models called ``neutral cloud theory.'' There also seems to have been an abrupt 20% decrease in N_e at about the time of the comet Shoemaker-Levy 9 impacts on Jupiter, as though a magnetospheric disturbance had increased the convective loss rate of the torus, but this may well be a coincidence. Simultaneous ground-based observations of the 6731 AA line do not constrain N_e decreases of this size, despite their low sensitivity to T_e, because they measure total torus mass only approximately.

Affiliated with

Also associated with

No associations

Rating

Disentangling Electron Temperature and Density in the Io Plasma Torus does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Disentangling Electron Temperature and Density in the Io Plasma Torus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Disentangling Electron Temperature and Density in the Io Plasma Torus will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1188210