An outburst powered by the merging of two stars inside the envelope of a giant

Shlomi Hillel, Ron Schreier, Noam Soker

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


We conduct 3D hydrodynamical simulations of energy deposition into the envelope of a red giant star as a result of the merger of two close main sequence stars or brown dwarfs, and show that the outcome is a highly non-spherical outflow. Such a violent interaction of a triple stellar system can explain the formation of 'messy', i.e. lacking any kind of symmetry, planetary nebulae and similar nebulae around evolved stars. We do not simulate the merging process, but simply assume that after the tight binary system enters the envelope of the giant star the interaction with the envelope causes the two components, stars or brown dwarfs, to merge and liberate gravitational energy. We deposit the energy over a time period of about 9 h, which is about 1 per cent of the the orbital period of the merger product around the centre of the giant star. The ejection of the fast hot gas and its collision with previously ejected mass are very likely to lead to a transient event, i.e. an intermediate luminosity optical transient.

Original languageEnglish
Pages (from-to)3456-3464
Number of pages9
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
StatePublished - 2017
Externally publishedYes


  • Binaries: close
  • Planetary nebulae: general
  • Stars: AGB and post-AGB


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