Deep Optical Emission-Line Images of Nine Known and Three New Galactic Supernova Remnants

TL;DR

This study provides deep optical images of 12 Galactic supernova remnants, revealing new structures and three previously unknown remnants, emphasizing the importance of [O III] imaging for understanding shock emissions.

Contribution

It presents the first deep optical emission-line images of nine known and three new Galactic SNRs, discovering three new remnants and highlighting the significance of [O III] imaging.

Findings

Discovered three new supernova remnants.

Revealed complex remnant structures and shock extensions.

Demonstrated the effectiveness of [O III] imaging in mapping shock emissions.

Abstract

Deep optical emission-line images are presented for nine known plus three new Galactic supernova remnants (SNRs), all but one having at least one angular dimension greater than one degree. Wide-field images taken in H$\alpha$ and [O III] $\lambda$5007 reveal many new and surprising remnant structures including large remnant shock extensions and `breakout' features not seen in published optical or radio data. These images represent over 12,000 individual images totaling more than 1000 hours of exposure time taken over the last two years mainly using small aperture telescopes which detected fainter nebular line emissions than published emission-line images. During the course of this imaging program, we discovered three new SNRs, namely G107.5-5.1 (the Nereides Nebula), G209.9-8.2, and G210.5+1.3, two of which have diameters >1.5 degrees. Besides offering greater structural detail on the nine already known SNRs, a key finding of this study is the importance of [O III] emission-line imaging for mapping the complete shock emissions of Galactic SNRs.