A star with a mass of more than eight times of the Sun releases tremendous energy when it is dying and undergoes a supernova explosion. The shockwave caused by the supernova explosion expands, having a strong impact on the composition and physical state of surrounding interstellar materials. It also emits kinetic energy into interstellar space. “Galactic winds” blasting out a large amount of gas are often observed in galaxies where explosively active star formations take place. The energy source of such galactic wind is also thought to be many supernova explosions.
Thus, supernova explosions have an immense influence on interstellar space. Nevertheless, there has been no quantitative research on the expansion velocity and kinetic energy of a supernova shockwave. This is because wide area must be observed in order to study the expansion velocity and kinetic energy of a supernova shockwave. Wide area observations with the existing equipment require quite long observation times. Therefore, observations of interstellar gas influenced by a supernova shockwave have been limited to a narrow area.