The nature of the Napoleon's Hat nebula of SN 1987A

Abstract

Recent observations of the Napoleon's Hat nebula of SN 1987A show that it can be described by a bow shock on the northern side of the supernova. Because of its location close to the supernova, Napoleon's Hat is doubtless affected by the wind from the precursor. It has previously been shown that the supernova is located at the top of a cocoon-shaped dark bay. By modelling the structure and dynamical formation of Napoleon's Hat and the dark bay, we conclude that the supernova progenitor star was in motion with respect to its circumstellar environment. The dark bay was produced by the shock interaction between the interstellar medium and the energetic wind of the precursor when in its main-sequence stage