The interaction of supernova 2018evt with a substantial amount of circumstellar matter – An SN 1997cy-like event

A rare class of supernovae (SNe) is characterized by strong interaction between the ejecta and several solar masses circumstellar matter (CSM) as evidenced Balmer-line emission. Within first few weeks after explosion, they may display spectral features similar to overluminous Type Ia SNe, while at later phase their observation properties exhibit remarkable similarities with some extreme case IIn SNe that show Balmer lines years explosion. We present polarimetric observations SN2018evt obtained ESO Very Large Telescope from 172 219 days estimated time peak luminosity study geometry CSM. The nonzero continuum polarization decreases over time, suggesting mass loss progenitor star aspherical. prominent H$\alpha$ emission can be decomposed into a broad, time-evolving component an intermediate-width, static component. former shows polarized signals, it likely arise cold dense shell (CDS) within region forward reverse shocks. latter significantly unpolarized, shocked, fragmented gas clouds in H-rich infer exploded inside massive aspherical cloud. symmetry axes CSM SN appear similar. SN\,2018evt observational common events CSM, implying share configurations. Our preliminary estimate also suggests environment has been enriched rate $\sim0.1$ M$_\odot$ yr$^{-1}$ period $>100$ yr.