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M. Kagitani, H. Misawa, S. Okano (Planetary Plasma and Atmospheric Research Center, Tohoku University, Japan)
Io's corona, from the exobase to the Lagrange sphere, is strongly related to the interaction between the Io's atmosphere and the plasma torus. However, it is extremely difficult to make observation of the sodium emission in the Io's corona with sufficient spatial resolution due to variation of the Earth's atmospheric seeing and bright reflection of solar continuum from Io's surface. In order to obtain spatial distribution of Io's corona, high dispersive (\lambda/\delta\lambda~51,000 at 589 nm) imaging observation of NaD 589.0 nm emission was carried out using an adaptive optics with a Fabry-Perot Imager coupled to the U.S. Air Force's 3.67 m AEOS telescope at Haleakala in Maui on March 21, 2005. At the time of observation, Io phase angle was 297 degree and System III longitude of Io was 82 degree.
The most profound and unexpected result is spherical asymmetric distribution of sodium corona; brightness of northern sub-Jupiter hemisphere is about twice larger than the opposite hemisphere. Possible explanations of spherical asymmetry will be discussed in this presentation.
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.