Formation of Double Rings Around Evolved Stars

Abstract

I propose a scenario for the formation of double-ring systems, as observed in some planetary nebulae and in the outer rings of SN 1987A. In this scenario, two jets, one jet on each side of the equatorial plane, expand into a thin, dense shell. Such a flow is expected in binary systems where the mass-losing primary undergoes an impulsive mass loss episode which forms a thin, dense shell. I assume that a small fraction of that mass is accreted onto a companion which blows the jets. Each jet accelerates shell's material it hits sideways, forming a higher density ring. Using several simplifying assumptions, I derive an expression for the radius of the ring, which depends relatively weakly on the jets and impulsive mass loss episode properties. This shows that such a scenario is feasible. If there are several such impulsive mass loss episodes, more double rings will be formed, as observed in the planetary nebulae MyCn 18 (the Hourglass nebula). Because of the binary interaction and orbital motion, the double-ring system is displaced from the symmetry axis of the main nebula, as observed.

11 pages, Submitted to ApJ

References in corpus (6)

• Hydrodynamical Simulations of Jet- and Wind-driven Protostellar Outflows
• A ballistic bow shock model for jet-driven protostellar outflow shells
• Collimated Fast Winds in Wide Binary Progenitors of Planetary Nebulae
• Departure from Axisymmetry in Planetary Nebulae
• A disrupted circumstellar torus inside eta Carinae's Homunculus Nebula
• Discovery of a double ring in the core of eta Carinae

Cited by in corpus (5)

• And in the Darkness Bind Them: Equatorial Rings, B[e] Supergiants, and the Waists of Bipolar Nebulae
• The role of jets in exploding supernovae and in shaping their remnants
• The Shaping of the Red Rectangle Proto-Planetary Nebula
• The Origin of Ionized Filaments Within the Orion-Eridanus Superbubble
• Bipolar rings from jet-inflated bubbles around evolved binary stars