The dynamics, stability and manifestation of circumbinary orbits

Thesis

I numerically investigate the dynamics of orbits in 3D circumbinary phase-space as a function of binary eccentricity and mass fraction. I find that inclined circumbinary orbits in the elliptically-restricted three-body problem display a nodal libration mechanism in the longitude of the ascending node and in the inclination to the plane of the binary. I analyse and quantify the behaviour of these orbits and investigate their stability over time. This work is the first dynamically aware analysis of the stability of circumbinary orbits across both binary mass fraction and binary eccentricity. This work also has implications for exoplanetary astronomy in the existence and determination of stable orbits around binary systems.

I also present an examination of the so-called radio ruff around the microquasar SS433, which I show to precess on a timescale of approximately 550 days. The observed precession in the projected angle of the ruff on the sky may be explained if the ruff feature arises from an inclined circumbinary excretion disk. In addition, I describe a pilot study in the near-infrared waveband in search of circumbinary material around other microquasars.

Authors: Doolin, S

• Publication date: 2012
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: Oxford University, UK
• Language: English
• Keywords: circumbinary; stars; binaries
• Subjects: Physics; Physical Sciences; Astrophysics