We present optical photometry and spectroscopy of SN 2019hnl. Discovered within ~26 hr of explosion by the ATLAS survey, SN 2019hnl is a typical Type IIP supernova with a peak absolute V band magnitude of -16.7+-0.1 mag, a plateau length of ~107 days, and an early decline rate of 0.0086+-0.0006 mag (50 days)^-1. We use nebular spectroscopy and hydrodynamic modeling with the SNEC, MESA, and STELLA codes to infer that the progenitor of SN 2019hnl was a M_ZAMS ~ 11M_solar red supergiant which produced 0.047+-0.007M_solar of 56Ni in the explosion. As a part of our hydrodynamic modeling, we reduced hydrogen envelope mass by scaling the mass loss within the "Dutch" wind scheme to fit our light curve, showing that the progenitor of a relatively typical Type IIP SN may experience partial stripping during their evolution and establish massive (~0.2M_solar) CSM environments prior to core collapse.
@article{arxiv.2509.03732,
title = {SN 2019hnl: A Type IIP Supernova with a Partially Stripped, Low Mass Progenitor},
author = {Aidan Martas and Stefano Valenti and Aravind P. Ravi and Yize Dong and K. Azalee Bostroem and Jeniveve Pearson and Manisha Shrestha and Jennifer E. Andrews and David J. Sand and Griffin Hosseinzadeh and Michael Lundquist and Emily Hoang and Darshana Mehta and Nicolas Meza Retamal and Saurabh W. Jha and Daryl Janzen and D. Andrew Howell and Curtis McCully and Daichi Hiramatsu and Craig Pellegrino},
journal= {arXiv preprint arXiv:2509.03732},
year = {2025}
}