Near-Infrared Spectroscopy of SN 2017eaw in 2017: Carbon Monoxide and Dust Formation in a Type II-P Supernova

TL;DR

This study presents near-infrared spectra of SN 2017eaw, revealing early CO formation and hot dust creation, providing insights into dust production mechanisms in Type II-P supernovae and their role in cosmic dust origins.

Contribution

It provides the first detailed near-infrared spectral analysis of SN 2017eaw, showing CO and dust formation timelines consistent with chemical models, advancing understanding of supernova dust production.

Findings

CO formation observed between 124-205 days post-discovery

Hot dust continuum emission detected at wavelengths >2.1 microns

Estimated CO masses around 10^{-4} solar masses, possibly higher under non-LTE conditions

Abstract

The origin of dust in the early Universe has been the subject of considerable debate. Core-collapse supernovae (ccSNe), which occur several million years after their massive progenitors form, could be a major source of that dust, as in the local universe several ccSNe have been observed to be copious dust producers. Here we report nine near-infrared (0.8 - 2.5 micron) spectra of the Type II-P SN 2017eaw in NGC 6946, spanning the time interval 22 - 205 days after discovery. The specta show the onset of CO formation and continuum emission at wavelengths greater than 2.1 micron from newly-formed hot dust, in addition to numerous lines of hydrogen and metals, which reveal the change in ionization as the density of much of the ejecta decreases. The observed CO masses estimated from an LTE model are typically 10^{-4} Msun during days 124 - 205, but could be an order of magnitude larger if non-LTE conditions are present in the emitting region. The timing of the appearance of CO is remarkably consistent with chemically controlled dust models of Sarangi & Cherchneff.