FINAL SIZE OF A MAGNETIZED SUPERBUBBLE

We discuss the final size of a magnetized superbubble and suggest that its size is determined by the balance between magnetic tension and bu oyancy. The former is estimated from the radius of the bubble and the magnetic held in the supershell. The later originates from the differe nce between the shell density and the coronal gas density inside the b ubble. When the buoyancy dominates the magnetic tension, the superbubb le is transformed into the so-called chimney. The final size of such a magnetized superbubble prior to the chimney structure is several hund red parsecs. To determine its size, Vallee's law to describe the evolu tion of the magnetized supershell is essential.