Why magnetic fields cannot be the main agent shaping planetary nebulae

Noam Soker*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

65 Scopus citations


An increasing amount of the literature reports the detection of magnetic fields in asymptotic giant branch (AGB) stars and in central stars of planetary nebulae (PNe). These detections lead to claims that the magnetic fields are the main agent shaping the PNe. In this paper, I examine the energy and angular momentum carried by magnetic fields expelled from AGB stars, as well as other physical phenomena that accompany the presence of large-scale fields, such as those claimed in the literature. I show that a single star cannot supply the energy and angular momentum if the magnetic fields have the large coherent structure required to shape the circumstellar wind. Therefore, the structure of nonspherical planetary nebulae cannot be attributed to dynamically important large-scale magnetic fields. I conclude that the observed magnetic fields around evolved stars can be understood with respect to locally enhanced magnetic loops, which can have a secondary role in the shaping of the PN. The primary role, I argue, rests with the presence of a companion.

Original languageEnglish
Pages (from-to)260-269
Number of pages10
JournalPublications of the Astronomical Society of the Pacific
Issue number840
StatePublished - Feb 2006
Externally publishedYes

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