Supershell GS235-02:Morphology and Kinematics

We have carried out infrared (IR), Hi and CO studies of the large shell GS235-02 in our galaxy. In IR, GS235-02 appears as an almost complete loop elongated ( ~ 8(deg) times 6(deg) ) along the north-south direction. The loop is composed of bright Hii regions immersed in a diffuse emission. By analyzing IRAS and COBE data, we have found that the diffuse IR emission has both cold ( ~ 25 K) and warm (> 200 K) components. From Weaver-Williams H I survey data, we have identified a loop structure corresponding to the IR loop. The structure appears most clearly between v_LSR=+25 and +31 km s(-1) . As the velocity increases, the loop appears smaller, which indicates that GS235-02 is expanding with v_exp ~ 15 km s(-1) . Molecular emission is associated with the loop at the velocity range of +18 to +42 km s^{-1}, which is within the velocity range of Hi Using the kinematic distance to the shell of 2.5 kpc, the mass, momentum, and kinetic energy of the shell are 1.4x10(6) M_sun, 2.1x10(7) M_sun km s(-1) , and 3.2x10⁵¹ ergs. Hence, GS235-02 appears as one of the supershells outside the solar circle. IR images suggest that the shell already has broken through the dense {sc Hi} layer. The {sc Hii} regions associated with the shell indicate that the star formation has been induced. We discuss the evolutionary history of GS235-$02.