Hydrodynamic simulations of the interaction between an AGB star and a main-sequence companion in eccentric orbits. Issue 4 (30th November 2015)

• Record Type: Journal Article
• Authors: Staff, Jan E.; De Marco, Orsola; Macdonald, Daniel; Galaviz, Pablo; Passy, Jean-Claude; Iaconi, Roberto; Low, Mordecai-Mark Mac
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 455:Issue 4(2016)
• Page Start: 3511
• Page End: 3525
• Publication Date: 2015-11-30
• Subjects: hydrodynamics -- methods: numerical -- binaries: close -- stars: evolution; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stv2548
• Languages: English
• ISSNs: 0035-8711

Abstract

Abstract: 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.