Deborah Levine 1, Mark Morris 2, & Don Figer 2
1 SIRTF Science Center IPAC
2 University of California Los Angeles
The QPS (Quintuplet, Pistol, Sickle) Region and the non-thermal filaments in the Galactic Center have been a long-standing puzzle. Recently a coherent picture has been assembled in which the extremely massive Quintuplet stellar cluster (Figer et al. 1995, 1996) produces the ionizing flux to create the G0.18-0.04 HII region (known to afficianados as the ``Sickle''), poised at the edge of the 25 km/s molecular cloud (Serabyn & Guesten 1991). Some of the electrons in the ionized gas at molecular cloud surfaces are then subject to acceleration to relativistic energies by magnetic field line reconnection and as these particles stream way from the site of acceleration along strong magnetic field lines, they create the non-thermal filaments, or NTF's (Serabyn and Morris 1994).
But there may be more to the story than that. The Sickle neatly follows the rim of a large (500" = 20 pc) circular ring which is faint but distinct at 20cm and barely visible at 6 cm (Yusef-Zadeh and Morris 1987, Figer 1996, Simpson 1996). Some early MSX (Midcourse Space Explorer) results which are available on the WWW (MSX Celestial Background Team 1996) clearly show this bubble at 20um, and it is faintly discernable in resolution-enhanced (HIRES) IRAS images at 12, 25 and 60 microns. However, only in the MSX images can this feature be clearly distinguished from other features and from more diffuse emission. In the 6 cm image, the rim of this ring or bubble located directly opposite from the Sickle feature also appears to show some brightening where it is crossed by the nonthermal filaments.
We present SWS01 speed 4 spectra of 3 positions around the ring. We detect several Fe and Si lines at high signal to noise. The 3 positions were chosen based on the 20 cm morphology of the region and consist of 1 position where the ``bubble'' appears to be interacting with the Sickle/NTF system, 1 position which appears relatively typical and one off-source position at the center of the ``bubble'' which is relatively free from structure in both the 20cm maps and the HIRES 25 um and 60 um images.