SIMBAD references

We study the morphologies of core collapse supernova remnants (CCSNRs) and find that about third of CCSNRs in our sample have two opposite 'ears' protruding from their main shell. We assume that the ears are formed by jets, and argue that these properties are compatible with the expectation from the explosion jet feedback mechanism. Based on previous studies of ears in CCSNRs and the similarity of some ears to those found in planetary nebulae, we assume that the ears are inflated by jets that are launched during the explosion, or a short time after it. Under simple geometrical assumptions, we find that the extra kinetic energy of the ears is in the range of 1-10 per cent of the explosion energy. As not all of the kinetic energy of the jets ends in the ears, we estimate that the typical kinetic energy in the jets that inflated the ears, under our assumptions, is about 5-15 per cent of the explosion energy. This study supports a serious consideration of jet-driven core-collapse supernova mechanisms.