Exploring the Kinematics of the Oxygen-rich Supernova Remnant G292.0+1.8: Ejecta Shells, Fast-moving Knots and Shocked Circumstellar Material

We present results of an in-depth optical study of the core collapse supernova remnant G292.0+1.8 using the Rutgers Fabry-Perot (RFP) imaging spectrometer. Our observations provide a detailed picture of the supernova remnant in the emission lines of [O III] λ5007, Hα and [N II] λ6548. The [O III] Fabry-Perot scans reveal a bright crescent-shaped spur of previously known high-velocity (Vradial ∼ 1500 km s ) O-rich ejecta located on the eastern side of the remnant. The spur consists of a semi-coherent structure of mostly redshifted material, along with several clumps that have apparently broken out of the more orderly shell-like expansion. The high velocity (∼> 600 km s −1 ) component of the spur also displays a scalloped morphology characteristic of Rayleigh-Taylor instabilities. We also find a large number of fast-moving knots (FMKs) of O-rich ejecta undetected in prior photographic plate images and similar to features seen in Cas A. The FMKs are distributed sparsely in the interior of G292.0+1.8 and are seen mostly in blueshifted emission out to Vradial ≈−1700 km s −1 . The position-velocity distribution of the FMKs can be kinematically described as a shell 3.4 in radius expanding at a velocity of 1700 km s . Another feature apparent in the [O III] scans is an equatorial belt consisting of both a bar-like structure at zero radial velocity and a clumpy, high velocity ejecta component seen in projection along the line of sight. Portions of the zero-velocity bar are spatially well correlated with a similar structure seen in the Chandra X-ray image of G292.0+1.8. The bar is also detected in our Hα RFP images at zero radial velocity, providing further evidence that this structure is of circumstellar origin. We find that the optical and X-ray properties of the bar are consistent with incomplete (partially radiative) shocks in material of moderate densities. There are also a number of faint, elongated structures seen in Hα at zero radial velocity across the interior of G292.0+1.8 that lack [O III] and X-ray counterparts. These filaments may be low-density H I clouds photoionized by hard radiation from the interior of the remnant. Overall these results suggest that G292.0+1.8 is currently interacting with a low density environment. We find no evidence for high velocity Hα or [N II] emission over the dynamical range sampled by the RFP. Assuming a distance of 6 kpc for G292.0+1.8, we estimate a kinematic age of (3000–3400) d6 years for this remnant. Subject headings: supernova remnants — ISM: individual (G292.0+1.8)