Studies on dynamical processes among Mercury's atmosphere, magnetosphere and the solar wind based on 2D imaging observations for Mercury's atmospheric emissions

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1) Development of the 2D imaging system for atmospheric emission of MercuryThe 2D imaging system for detection of Na-D line emission of Mercury's atmosphere is successfully developed. The back-end of the system consists of temperature and tilt-angle controlled interference filter and electrically cooled 2D CCD camera. The band-width of the filter is only 0.13nm (FWHM) for reducing the contamination caused by continuum emissions from the day-side area of Mercury. The temperature control function is used for adjusting the center wavelength of the filter against changes in ambient temperature, while the tilt-angle control function is used for changing the center wavelength in a short time to observe both a Na-D line image and back-ground emission image as a reference. The back-end is attached to the 60cm φ F/24 coude telescope system of Tohoku University.2) Observations of Na-D line emission of Mercury's atmosphereThe observations were made from Nov. to Dec. 2000. Due to small solar elong … More ation of Mercury, the observations were made in the twilight period at low elevation angle. The trackingg error of the telescope system was therefore inevitably large. The error has not been fully compensated during this research period, then, reliable images have not been acquired successfully. However, we have established analysis methods which are required to derive 2D image of Mercury's atmosphere ; i.e., the compensation method for atmospheric smearing and the reduction method of back-ground emission.3) Development of Monte-Carlo simulation model for Mercury's atmosphereA Monte-Carlo simulation model for neutral and ionized particles has been developed under the consideration of gravity forces of Mercury and the sun and the presence of magnetic field of Mercury. Three main gas release processes are taken into account in the model ; photon-stimulated desorption, ion sputtering and meteoritic vaporization. Although quantitative investigations of dynamical processes among Mercury's atmosphere, magnetosphere and the solar wind are deferred for future studies due to lack of reliable data, a significant model has been established in this research. Less