# The Type II-Plateau Supernova 2017eaw in NGC 6946 and Its Red Supergiant Progenitor

## TL;DR

This paper provides comprehensive optical observations and analysis of SN 2017eaw, confirming its progenitor as a dusty red supergiant with an initial mass of about 15 solar masses, and refines its distance and properties.

## Contribution

It offers detailed observational data and modeling of SN 2017eaw and its progenitor, including distance measurement and progenitor characterization, enhancing understanding of Type II-P supernovae.

## Key findings

- SN 2017eaw is a typical Type II-P supernova with properties between SN 1999em and SN 2012aw.
- The progenitor was a dusty, luminous red supergiant with an initial mass of approximately 15 solar masses.
- The distance to NGC 6946 was confirmed to be about 7.73 Mpc using multiple methods.

## Abstract

We present extensive optical photometric and spectroscopic observations, from 4 to 482 days after explosion, of the Type II-plateau (II-P) supernova (SN) 2017eaw in NGC 6946. SN 2017eaw is a normal SN II-P intermediate in properties between, for example, SN 1999em and SN 2012aw and the more luminous SN 2004et, also in NGC 6946. We have determined that the extinction to SN 2017eaw is primarily due to the Galactic foreground and that the SN site metallicity is likely subsolar. We have also independently confirmed a tip-of-the-red-giant-branch (TRGB) distance to NGC 6946 of 7.73+/-0.78 Mpc. The distances to the SN that we have also estimated via both the standardized candle method and expanding photosphere method corroborate the TRGB distance. We confirm the SN progenitor identity in pre-explosion archival Hubble Space Telescope (HST) and Spitzer Space Telescope images, via imaging of the SN through our HST Target of Opportunity program. Detailed modeling of the progenitor's spectral energy distribution indicates that the star was a dusty, luminous red supergiant consistent with an initial mass of ~15 Msuns.