Supershell GS235$-$02:Morphology and Kinematics

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Session 82 -- HII Regions
Display presentation, Wednesday, 11, 1995, 9:20am - 6:30pm

[82.12] Supershell GS235$-$02:Morphology and Kinematics

Jae Hoon Jung and Youngung Lee (Korea Astronomy Observatory), \ \ \ \ \ Bon-Chul Koo (Seoul National University)

\def\gs{GS235$-$02} \def\vlsr{v_{\rm LSR}} \def\kms{km~s$^{-1}$}

We have carried out infrared (IR), {\sc Hi} and CO studies of the large shell \gs\ in our galaxy. In IR, \gs\ appears as an almost complete loop elongated ($\sim 8^{\circ} \times 6^{\circ}$) along the north-south direction. The loop is composed of bright {\sc Hii} regions emmersed in a diffuse emission. By analyzing IRAS and COBE data, we have found that the diffuse IR emission has both cold ($\sim$25~K) and warm ($>$ 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 $\vlsr=+25$ and +31~\kms. As the velocity increases, the loop appears smaller, which indicates that \gs\ is expanding with $v_{\rm exp} \sim 15$~\kms. Molecular emission is associated with the loop at the velocity range of $+18$ to $+42$ \kms, which is within the velocity range of {\sc 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$_\odot$, 2.1x10$^7$~M$_\odot$~\kms, and 3.2x10$^{51}$~ergs. Hence, \gs\ 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 \gs.

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