Hydrodynamic simulations of the interaction between an AGB star and a main-sequence companion in eccentric orbits

Jan E. Staff*, Orsola De Marco, Daniel Macdonald, Pablo Galaviz, Jean Claude Passy, Roberto Iaconi, Mordecai Mark Mac Low

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

49 Citations (Scopus)


The Rotten Egg Nebula has at its core a binary composed of a Mira star and an A-type companion at a separation > 10 au. It has been hypothesized to have formed by strong binary interactions between the Mira and a companion in an eccentric orbit during periastron passage ~800 yr ago. We have performed hydrodynamic simulations of an asymptotic giant branch (AGB) star interacting with companions with a range of masses in orbits with a range of initial eccentricities and periastron separations. For reasonable values of the eccentricity, we find that Roche lobe overflow can take place only if the periods are ≪ 100 yr. Moreover, mass transfer causes the system to enter a common envelope phase within several orbits. Since the central star of the Rotten Egg nebula is an AGB star, we conclude that such a common envelope phase must have lead to a merger, so the observed companion must have been a tertiary companion of a binary that merged at the time of nebula ejection. Based on the mass and time-scale of the simulated disc formed around the companion before the common envelope phase, we analytically estimate the properties of jets that could be launched. Allowing for super-Eddington accretion rates, we find that jets similar to those observed are plausible, provided that the putative lost companion was relatively massive.

Original languageEnglish
Pages (from-to)3511-3525
Number of pages15
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
Publication statusPublished - 1 Feb 2016


  • hydrodynamics
  • methods: numerical
  • binaries: close
  • stars: evolution


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