# Evolution and Explosion of Massive Stars Leading to IIP-IIL SNe with MESA and SNEC

## TL;DR

This study investigates how dense circumstellar material around red supergiants influences the early light curves of Type II-P supernovae, showing that CSM affects peak brightness, decline, and plateau duration, and reduces required explosion energy.

## Contribution

It demonstrates the impact of circumstellar shells on supernova light curves and explosion energies using MESA and SNEC modeling, highlighting the role of pre-supernova mass loss.

## Key findings

- Dense CSM alters supernova light curve features.
- Explosion energy is reduced by nearly half with CSM.
- Early light curve peaks are significantly affected.

## Abstract

We show how the dense shells of circumstellar gas immediately outside the red supergiants (RSGs) can affect the early optical light curves of Type II-P SNe taking the example of SN 2013ej. The peak in V, R and I bands, decline rate after peak and plateau length are found to be strongly influenced by the dense CSM formed due to enhanced mass loss during the oxygen and silicon burning stage of the progenitor. We find that the required explosion energy for the progenitors with CSM is reduced by almost a factor of 2.