# SN 2017gmr: An energetic Type II-P supernova with asymmetries

## TL;DR

SN 2017gmr is a luminous Type II-P supernova exhibiting asymmetries and signs of circumstellar interaction, with detailed multi-wavelength observations revealing insights into its progenitor, explosion asymmetry, and radioactive decay contributions.

## Contribution

This study provides comprehensive high-cadence UV, optical, and NIR data on SN 2017gmr, highlighting asymmetries and CSM interaction effects in a Type II-P supernova for the first time.

## Key findings

- Progenitor radius estimated at ~500 R_sun.
- Up to 0.130 M_sun of nickel synthesized.
- Asymmetric explosion or CSM asymmetries indicated by emission lines.

## Abstract

We present high-cadence ultraviolet (UV), optical, and near-infrared (NIR) data on the luminous Type II-P supernova SN 2017gmr from hours after discovery through the first 180 days. SN 2017gmr does not show signs of narrow, high-ionization emission lines in the early optical spectra, yet the optical lightcurve evolution suggests that an extra energy source from circumstellar medium (CSM) interaction must be present for at least 2 days after explosion. Modeling of the early lightcurve indicates a ~500R$_{\odot}$ progenitor radius, consistent with a rather compact red supergiant, and late-time luminosities indicate up to 0.130 $\pm$ 0.026 M$_{\odot}$ of $^{56}$Ni are present, if the lightcurve is solely powered by radioactive decay, although the $^{56}$Ni mass may be lower if CSM interaction contributes to the post-plateau luminosity. Prominent multi-peaked emission lines of H$\alpha$ and [O I] emerge after day 154, as a result of either an asymmetric explosion or asymmetries in the CSM. The lack of narrow lines within the first two days of explosion in the likely presence of CSM interaction may be an example of close, dense, asymmetric CSM that is quickly enveloped by the spherical supernova ejecta.