Ring ejection in type II supernovae - IE 0102.2-7219 in the small magellanic cloud

A velocity map is presented of the young oxygen-rich supernova remnant (IE 0102.2-7219) in the Small Magellanic Cloud, obtained with the Anglo-Australian Telescope. The velocity structure is complex and implies a high degree of asymmetry during the type II supernova explosion. Our velocity data can be modeled in terms of a severely distorted ring of ejecta. This result, together with the evidence for expanding rings in similar remnants, suggests nonspherical ejection to be an intrinsic characteristic of type II supernova. Two-dimensional spectroscopy of the diffuse halo of emission which partially surrounds IE 0102.2-7219 has also been obtained. The halo emits in the He II 4686 wavelength line and is either a fossil H II region created by a UV flash accompanying the supernova, or alternatively is being excited by intense UV radiation from the remnant itself. It is the first clear association of a high-excitation region with a supernova remnant.