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Preplanetary nebulae : a Hubble Space Telescope imaging survey and a new morphological classification system

Show simple item record Sahai, Raghvendra Morris, Mark Sanchez Contreras, Carmen Claussen, Mark 2008-10-08T21:48:05Z 2008-10-08T21:48:05Z 2007-12
dc.identifier.citation The Astronomical Journal, 134:2200-2225, 2007 December en_US
dc.identifier.clearanceno 07-3211
dc.description.abstract Using the Hubble Space Telescope (HST ), we have carried out a survey of candidate preplanetary nebulae (PPNs). We report here our discoveries of objects having well-resolved geometric structures, and we use the large sample of PPNs now imaged with HST (including previously studied objects in this class) to devise a comprehensive morphological classification system for this category of objects. The wide variety of aspherical morphologies which we have found for PPNs are qualitatively similar to those found for young planetary nebulae (PNs) in previous surveys. We also find prominent halos surrounding the central aspherical shapes in many of our objects; these are direct signatures of the undisturbed circumstellar envelopes of the progenitor AGB stars. Although the majority of these have surface brightness distributions consistent with a constant mass-loss rate with a constant expansion velocity, there are also examples of objects with varying mass-loss rates. As in our surveys of young PNs, we find no round PPNs. The similarities in morphologies between our survey objects and young PNs supports the view that the former are the progenitors of aspherical PNs. This suggests that the primary shaping of a PN does not occur during the PN phase via the fast radiative wind of the hot central star, but significantly earlier in its evolution. en_US
dc.description.sponsorship NASA/JPL en_US
dc.language.iso en_US en_US
dc.publisher The American Astronomical Society en_US
dc.subject circumstellar matter en_US
dc.subject planetary nebulae en_US
dc.subject AGB and post-AGB en_US
dc.subject mass loss en_US
dc.title Preplanetary nebulae : a Hubble Space Telescope imaging survey and a new morphological classification system en_US
dc.type Article en_US

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