Planetary Nebulae that Cannot Be Explained by Binary Systems

Abstract

We examine the images of hundreds of planetary nebulae (PNe) and find that for about one in six PNe the morphology is too 'messy' to be accounted for by models of stellar binary interaction. We speculate that interacting triple stellar systems shaped these PNe. In this preliminary study we qualitatively classify PNe by one of four categories.(1) PNe that show no need for a tertiary star to account for their morphology. (2) PNe whose structure possesses a pronounced departure from axial-symmetry and/or mirror-symmetry. We classify these, according to our speculation, as 'having a triple stellar progenitor'. (3) PNe whose morphology possesses departure from axialsymmetry and/or mirror-symmetry, but not as pronounced as in the previous class, and are classified as 'likely shaped by triple stellar system'. (4) PNe with minor departure from axialsymmetry and/or mirror symmetry that could have been as well caused by an eccentric binary system or the inter-stellar medium. These are classified as 'maybe shaped by a triple stellar system'. Given a weight η t = 1, η l = 0.67, η m = 0.33 to classes 2, 3 and 4, respectively, we find that according to our assumption about 13 − 21% of PNe have been shaped by triple stellar systems. Although in some evolutionary scenarios not all three stars survive the evolution, we encourage the search for a triple stellar systems at the center of some PNe.

Shaping planetary nebulae with jets in inclined triple stellar systems

“…These are subset of all triple stellar scenarios. The scenario studied in this paper, therefore, accounts for some fraction of the 12 per cents of PNe studied by Bear & Soker (2017). We crudely estimate that the scenario studied in this paper accounts for about 3-5 per cents of all non-spherical PNe.…”

“…However, we can learn from the recent study of Bear & Soker (2017). They present images of 4 typical messy PNe, that they claim are most likely have been shaped by a triple stellar system.…”

“…Bear & Soker (2017) estimate that about 13 to 21 per cents of non-spherical PNe have been shaped by triple stellar systems. Soker (2016) estimates that about one in eight non-spherical PNe is shaped by the PN AGB progenitor swallowing a binary system or interacting with a binary system close to its surface.…”

“…In most cases of shaping by binary interaction, jets are involved (e.g., Morris 1987;Soker 1990;Sahai & Trauger 1998;Boffin et al 2012;HuarteEspinosa et al 2012;Balick et al 2013;Miszalski et al 2013;Tocknell et al 2014;Huang et al 2016;Sahai et al 2016;Rechy-García et al 2016;García-Segura et al 2016, to list a small number out of hundreds of papers). A relatively small number of papers raise the possibility that triple stellar systems are behind the morphologies of some PNe (e.g., Soker 1994Soker , 2016Bear & Soker 2017;Jones 2017). A claim for a triple stellar system in the PN SuWt 2 (Bond et al 2002;Exter et al 2010) was rejected recently by Jones & Boffin (2017).…”

Kinematical investigation of possible fast collimated outflows in twelve planetary nebulae

“…The HST [N II] image (Figure 10-left) reveals an intricate morphology, with an S-shaped point-symmetric low-ionization structure suggestive of a precessing collimated outflow and a filamentary disk-like structure at the central nebular regions. Bear, & Soker (2017) suggested that M 3-1 maybe shaped by a triple stellar progenitor. It definitely harbors at least a closebinary system with a very short period (Jones et al 2019).…”