The first optical light from the supernova remnant G182.4+4.3 located in the Galactic anticentre region

Abstract

We report the discovery of optical filamentary and diffuse emission from G182.4+4.3 using the 1.5-m Russian-Turkish telescope. We present the optical CCD images obtained with the Hα filter, revealing the presence of mainly filamentary structure to the north-west and filamentary and diffuse structure in the centre, south and north regions of the remnant. The bright optical filaments located in the north-west and south regions are well correlated with the prominent radio shell of the remnant, strongly suggesting an association. From the flux-calibrated CCD imaging, the average [S II]/Hα ratio is found to be ∼0.9 and ∼1.1 for south and north-west regions, respectively, which clearly indicates that the emission originates from shock-heated gas. We also present the results of X-ray data obtained from XMM-Newton, showing diffuse emission with a very low luminosity of ∼7.3 × 10³¹ erg s^-1 at a distance of 3 kpc in the 0.3-10 keV energy band. Furthermore, we find a surprisingly low age of ∼4400 yr for this remnant, given its large radius of ∼22 pc.