heavy elements surface of stars first dredge up

Planetary nebulae were first identified as extended objects in the sky and were grouped together with stellar clusters, galaxies, diffuse nebulae, and supernova remnants in Charles Messier’s 1784 catalogue of nebulous objects.

In this paper, we summarize the recent observations of circumstellar synthesis of molecules and solids and discuss the implications of these ejected circumstellar materials on the chemical enrichment of the Galaxy and planetary systems. Stellar synthesized organic solids may survive their journeys through the interstellar medium and evidence for remnants of such organics can be found in our own Solar System. These ejected materials of planetary nebulae serve as primordial ingredients of formation of new stars and planetary systems. Planetary nebulae, formed by swept-up circumstellar material, are found to show strong spectral signatures of ions, atoms, molecules, and inorganic and organic solids. During the subsequent post-AGB evolution, complex organics with aromatic and aliphatic structures are synthesized in the circumstellar envelope. These molecules and solids are ejected into the interstellar medium by a strong stellar wind. Simple molecules and solid-state minerals begin to form in the upper photosphere. This is followed by the synthesis of other heavy elements via neutron capture in the core and the dredge-up of these elements to the surface by convection. 2Laboratory for Space Research, University of Hong Kong, Hong Kong SAR, Chinaĭuring the late asymptotic giant branch (AGB) phase of stellar evolution, the element carbon is created through the triple- α nuclear reaction.1Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, BC, Canada.

Heavy elements surface of stars first dredge up