Academia Sinica Logo

In recent years, observations of core-collapse supernovae have implied the possible presence of a dense circumstellar medium in the vicinity of the progenitor star. While this can be a clue to understand the mass-loss activity of massive stars in their final moments, it remains unspecified what the origin would be. One of the critical hints would be the asphericity of the circumstellar medium, as demonstrated by the detection of the polarization in the nearby supernova event SN 2023ixf. This makes us consider the scenario where the mass loss activity was executed in an aspherical way. In this talk, I will review the current understanding of how we interpret observational signatures of supernovae in the early phase, together with the inference of a circumstellar medium, and introduce my preliminary results about the examination of stellar rotation as a formation scenario of an aspherical circumstellar medium.