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   61108
   Supershells of HI were discovered from radio observation in the nearby
   spiral galaxy M108. M108 is nearly edge-on and known to exhibit
   evidences of active starforming activity. The supershells has extention
   of several kpc in diameter. Such supershells are thought to be formed
   by galactic wind as a result of starburst activity in the galaxy. We
   propose to observe the galaxy to investigate the hot gas outflow.
   Information obtained through the X-ray observation such as spatial
   extent, variation of the spectrum, elemental abundance of the hot gas
   will provide clues to understand the mechanism of formationof the
   supershells and the structual evolution of spiral galaxies.
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