Discovery of Extensive Optical Emission from the Extremely Radio Faint Galactic Supernova Remnant G182.4+4.3
Abstract
Wide-field Hα images of the radio faint Galactic supernova remnant G182.4+4.2 reveal a surprisingly extensive and complex optical emission structure with an unusual series of broad and diffuse filaments along the remnant's southwestern limb. Deep [O III] images reveal no appreciable remnant emission with the exception of a single filament coincident with the westernmost of the broad southwest filaments. The near total absence of [O III] emission suggests the majority of the remnant's optical emission arises from relatively slow shocks (< 80 km/s). Low-dispersion optical spectra of several regions in the remnant's main emission structure confirm a lack of appreciable [O III] emission and indicate [S II]/Halpha line ratios of 0.75 - 1.03, consistent with a shock-heated origin. We propose that G182.4+4.2 is a relatively large (d ∼50 pc at 4 kpc) and much older (age ∼40 kyr) supernova remnant than previously estimated, whose weak radio, X-ray and optical emissions are related to its age and location in a low density region some 12 kpc out from the Galactic center.
- Publication:
-
Supernova Remnants: An Odyssey in Space after Stellar Death II
- Pub Date:
- June 2019
- Bibcode:
- 2019sros.confE..43F