PI: Chu, You-Hua, University of Illinois at Urbana-Champaign, email@example.com
Address: Department of Astronomy, 1002 W. Green St., Urbana, IL 61801, USA
CoI: Gruendl, Robert, University of Illinois at Urbana-Champaign
CoI: Guerrero, Martin, University of Illinois at Urbana-Champaign
Title: Physical Structure of the Wind-Blown Bubble S 308
Abstract: \vspace*-0.35cm Many astronomical systems contain hot (10^6- 10^8 K) gas in contact with cool (\le10^4 K) gas. At the contact surface, or the interface, heat conduction and mass evaporation are expected to occur and affect the thermal structure and evolution of the system. Among all systems, wind blown bubbles present the cleanest interfaces, as they are not contaminated by strong shocks or confused by multiple interfaces along the line of sight. We have obtained \it XMM- Newton X-ray observations of S 308, one of the only two bubbles blown by single massive stars that show diffuse X-ray emission. Comparisons of the X-ray and optical images of S 308 show a gap of widths 100''- 200'' between the optical shell rim and the outer edge of the diffuse X-ray emission. This structure is qualitatively consistent with theoretical expectations of an interface. We intend to study the physical structure of this interface in detail. Our X-ray observations show the hot (10^6 K) gas and our FUSE observations of the O \sc vi emission will show the location of 3\times10^5 K gas at the interface. We request high-dispersion, long-slit echelle observations in the [O \sc iii] and H(alpha)+[N \sc ii] lines to determine the 3- dimensional structure of the nebular shell and the exact location of the contact surface between the hot interior gas and the cool nebular gas. These optical, X-ray, and UV observations will allow the first spatially- resolved description of an interface.
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