AN EXPANDING SHELL-LIKE MOLECULAR CLOUD NEAR THE GALACTIC-CENTER ARC

We found, from the data of our CS (J = 1-0/2-1) survey with the Nobeya ma 45 m telescope, that a molecular cloud associated with the ''vertic al filaments'' of the Galactic center are has a shell-like structure a nd is expanding with a velocity of 20 km s(-1). The limb of the shell has high density, n(H-2)= 6 x 10(4) cm(-3). The shell may have origina ted from 10-100 supernovae within the last 10(5) yr. At the point of c ontact with the filaments, the limb of the shell is deformed and the f ilaments are bent in the opposite direction. These compensative deform ations suggest that the shell is dynamically interacting with the fila ments. The interaction may activate relativistic electrons in the Gala ctic center are.