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).

Abstract
1. INTRODUCTION
2. THE RADIO CONTINUUM DATA AND THE Hi OBSERVATIONS
    2.1. Radio Continuum Surveys
    2.2. Hi Observations
3. RADIO CONTINUUM ANALYSIS
    3.1. Radio Continuum Sources in the Fields of G192.8-1.1
    3.2. Radio Continuum Decomposition and the Non-thermal Component
4. Hi RESULTS
    4.1. Hi Morphologies
    4.2. Properties of the Hi Shell
5. MULTI-WAVELENGTH VIEW OF G192.8-1.1 AND THE DISTANCE
    5.1. Radio Continuum and the Hi 21-cm Line
    5.2. Infrared Emission
    5.3. Distance to G192.8-1.1
6. ORIGIN OF G192.8-1.1
    6.1. Hi Shell
    6.2. Thermal Radio Continuum
    6.3. G192 as an Evolved Thermal-composite SNR InteractingWith NearbyMassive Stars
7. CONCLUSION
REFERENCES

• JI-HYUN KANG(Korea Astronomy and Space Science Institute) CORRESPONDING AUTHOR
• BON-CHUL KOO(Department of Physics and Astronomy, Seoul National University)
• DO-YOUNG BYUN(Korea Astronomy and Space Science Institute)