Far-Ultraviolet Observations of a Thermal Interface in the Orion-Eridanus Superbubble

Diffuse far-UV emission arising from the edge of the Orion-Eridanus superbubble has been observed with the SPEAR imaging spectrometer, revealing numerous emission lines arising from both atomic species and H2. Spatial variations in line intensities of C IV, Si II, and O VI, in comparison with soft X-ray, Hα, and dust data, indicate that these ions are associated with processes at the interface between hot gas inside the bubble and the cooler ambient medium. Thus our observations probe the physical conditions of an evolved thermal interface in the interstellar medium.