Planetary Nebulae – 22nd July 2004

Ken Harrison of Loughton A.S. came to talk to us about Planetary Nebulae. He started by showing us an animated montage of images of planetary nebulae, and then went on to give us a brief potted history of the first recorded observations (by Messier), the naming (by Herschel) and the first spectral analysis (by Huggins, who ascribed the oxygen lines prominent in the spectra to “nebulium”) of objects of this type. From there he led us through the initial fairly simple explanations for their formation to the much more complex explanations needed to esplain the details seen in these objects by the Hubble Space Telescope. These explanations were accompanied by animations, both computer-generated and from sequences of Hubble images. These objects are far more complex than early models suggested, and usually have a basically bi-polar form, a bit like an hourglass or a dumbell. The nearly circular ones are simply end-on views of these other more complex shapes. Detailed study of planetary nebulae promises to reveal much about the end stages of stellar evolution.

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