# The difficulty of inferring progenitor masses from Type II-Plateau supernova light curves

## TL;DR

This study demonstrates that Type II-P supernova light curves are degenerate with respect to progenitor mass, making it difficult to infer initial stellar masses solely from light curve data due to similar observable properties across different progenitor masses.

## Contribution

The paper provides a controlled experiment showing that supernova light curves and spectra are degenerate across different progenitor masses with similar envelope masses, challenging the reliability of mass inference from light curves.

## Key findings

- Light curves are similar for different progenitor masses with comparable envelope masses.
- Spectral features are degenerate and influenced by progenitor radius and oxygen yield.
- Light curve modeling cannot reliably determine progenitor mass due to degeneracies.

## Abstract

Much controversy surrounds the inferred progenitor masses of Type II-Plateau (II-P) supernovae (SNe). The debate is nourished by the discrepant results from radiation-hydrodynamics simulations, from pre-explosion imaging, and from studies of host stellar populations. Here, we present a controlled experiment using four solar metallicity models with zero-age main-sequence masses of 12, 15, 20, and 25Msun. Because of the effects of core burning and surface mass loss, these models reach core collapse as red-supergiant (RSG) stars with a similar H-rich envelope mass of 8 to 9Msun but with final masses in the range 11 to 16Msun. We explode the progenitors using a thermal bomb, adjusting the energy deposition to yield an asymptotic ejecta kinetic energy of 1.25 x 10^51 erg and an initial 56Ni mass of 0.04Msun. The resulting SNe produce similar photometric and spectroscopic properties from 10 to 200d. The spectral characteristics are degenerate. The scatter in early-time color results from the range in progenitor radii, while the differences in late-time spectra reflect the larger oxygen yields in more massive progenitors. Because the progenitors have a comparable H-rich envelope mass, the photospheric phase duration is comparable for all models; the difference in He-core mass is invisible. As different main-sequence masses can produce progenitors with a similar H-rich envelope mass, light curve modeling cannot provide a robust and unique solution for the ejecta mass of Type II-P SNe. The numerous uncertainties in massive star evolution and wind mass loss also prevent a robust association with a main-sequence star mass. Light curve modeling can at best propose compatibility.