Powered by Indico
Planetary nebulae (PNe) are created by low- and intermediate-mass stars when the ejected envelope of gas and dust is ionized by the hot remnant core. PNe show photo-dissociation regions (PDRs) just outside the ionized gas once Lyman radiation is fully absorbed. PDRs are neutral gas zones with atoms, dust, and molecules where UV radiation, with photon energy ranging from 13.6 to 6 eV, plays a critical role in heating and chemical processes. These regions are strongly linked to both ionized nebulae as well as the evolving star. PDRs are also seen adjacent to the HII regions in ISM. It is essential to model the photo-ionization and photo-dissociation region simultaneously in order to resolve the transition zone and to accurately reproduce the UV, optical and IR observations. Spectral synthesis code Cloudy v.23.01 is used to make such models for the two cases: 1. system with a static ionization front like HII regions and 2. system with a progressive ionization front like PN by trapping the ionization front. We discuss the synthetic observations of these two systems and compare their behaviours with different sets of stellar and nebular parameters.
BGS Office