FUSE Observations of the Loop I/Local Bubble Interaction Region
Abstract
We used the FUSE (Far Ultraviolet Spectroscopic Explorer ) satellite to observe O VI emission along two sight lines toward the edge of the interaction zone (IZ) between the Loop I superbubble and the Local Bubble. One sight line was chosen because material in the interaction zone blocks distant X-ray emission, and should thus do the same for nonlocal O VI emission. We measured an O VI intensity of Ishad = 2750 +/- 550 photons cm-2 s-1 sr-1 along this "shadowed" sight line, and Iunshad = 10,800 +/- 1200 photons cm-2 s-1 sr-1 along the other sight line. Given these results, very little (lesssim 800 photons cm-2 s-1 sr-1) of the emission arises from the near side of the interaction zone, which likely has an H I column density of about 4 × 1020 cm-2 along the "shadowed" sight line. The O VI emission arising within Loop I (~104 photons cm-2 s-1 sr-1) is probably associated with gas of ne ~ 0.1 cm-3 and an emitting path length of ~2.5 pc, suggesting it arises at interfaces rather than from gas filling Loop I. In contrast, the C III emission is similar along both sight lines, indicating that much of the emission likely arises on the near side of the interaction zone.
Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer. FUSE is operated for NASA by the Johns Hopkins University under NASA contract NAS5-32985.- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 2008
- DOI:
- 10.1086/588802
- Bibcode:
- 2008ApJ...681.1310S
- Keywords:
-
- ISM: bubbles;
- ISM: general;
- ISM: individual: Loop I;
- supernova remnants;
- ultraviolet: ISM