The peculiar X-ray morphology of the supernova remnant G292.0+1.8 - Evidence for an asymmetric supernova explosion

A high-resolution X-ray image from the Einstein Observatory of the young supernova remnant G292.0+1.8 (MSH 11-54), previously noted as peculiar in terms of its spectral and morphological properties at optical and radio wavelengths, also shows an unusual X-ray morphology. Instead of a limb-brightened X-ray shell characteristic of most supernova remnants, the remnant consists of a central bar-like feature superposed on an ellipsoidal disk of approximately uniform surface brightness. The bar emission is attributed to a ring of oxygen-rich material ejected in the equatorial plane of a massive rotating progenitor, and the uniform disk component to emission from material with roughly cosmic composition heated by the accompanying blast wave. This interpretation provides strong observational support for the rotating precursor model of a Type II supernova discussed by Woosley and Weaver.