arXiv:2107.14269 [astro-ph.SR]AbstractReferencesReviewsResources Classifications Subjects Themes Keywords bipolar planetary nebulae, outer hourglass structures, sub-eddington accretion scenario, shock-related equatorial spiderweb structures, pre-pn evolutionary stages Tags Journal Information Publisher Journal Year Month Volume Number Pages DOI URL Miscellaneous Typesetting Pages Language License Submit Reset