Global far-ultraviolet image of the eridanus superbubble observed by FIMS/SPEAR

Abstract

We present the first far-ultraviolet (FUV; 1350-1750 A) diffuse emission map of the Eridanus superbubble, obtained using the FIMS/SPEAR instrument. The features seen in the FUV image closely resemble those seen in the Ha map, including two prominent arcs identified earlier in H alpha. While it has been argued that the FUV emission in this region is mostly due to the scattering of star light by dust, a close spectral examination reveals that one of the arcs is abundant in molecules and dust while the other is mainly composed of atomic species. Upon comparison to emission maps in other bands (X-ray, IR, optical H alpha), we propose the most plausible geometrical structure of this region.