G192.8-1.1 has been known as one of the faintest supernova remnants (SNRs) in the Galaxy until the radio continuum of G192.8-1.1 is proved to be thermal by Gao et al. (2011). Yet, the nature of G192.8-1.1 has not been fully investigated. Here, we report the possible discovery of faint non-thermal radio continuum components with a spectral index α ~ 0.56 (Sν∝ν^-α) around G192.8-1.1, while most of the radio continuum emission is thermal. Also, our Arecibo Hi data reveal an Hi shell, expanding with an expansion velocity of 20 – 60 km s-1 , that has an excellent morphological correlation with the radio continuum emission. The estimated physical parameters of the Hi shell and the possible association of non-thermal radio continuum emission with it suggest G192.8-1.1 to be an ~ 0.3 Myr-old SNR. However, the presence of thermal radio continuum implies the presence of early-type stars in the same region. One possibility is that a massive star is ionizing the interior of an old SNR. If it is the case, the electron distribution assumed by the centrally-peaked surface brightness of thermal emission implies that G192.8-1.1 is a “thermal-composite” SNR, rather than a typical shell-type SNR, where the central hot gas that used to be bright in X-rays has cooled down. Therefore, we propose that G192.8-1.1 is an old evolved thermal-composite SNR showing recurring emission in the radio continuum due to a nearby massive star. The infrared image supports that the Hi shell of G192.8-1.1 is currently encountering a nearby star forming region that possibly contains an early type star(s).

We have searched for HI 21 cm line emission from shocked atomic gas associated with southern supernova remnants (SNRs) using data from the Southern Galactic Plane Survey. Among the 97 sources studied, we have detected 10 SNRs with high-velocity HI emission confined to the SNR. The large velocity and the spatial confinement suggest that the emission is likely from the gas accelerated by the SN blast wave. We also detected 22 SNRs which show HI emission significantly brighter than the surrounding regions over a wide (>10 km s-1) velocity interval. The association with these SNRs is less certain. We present the parameters and maps of the excess emission in these SNRs. We discuss in some detail the ten individual SNRs with associated high-velocity HI emission.