Related papers: Stellar and planetary Cassini states
We examine the stability of a low-mass stellar system surrounding a massive central object. Examples of such systems include the centers of galaxies or star clusters containing a massive black hole, and the Oort comet cloud. If the…
We study secular stability against a quasi-radial oscillation for rigidly rotating stars with soft equations of state in general relativity. The polytropic equations of state with polytropic index $n$ between 3 and 3.05 are adopted for…
We study spherical and disk clusters in a near-Keplerian potential of galactic centers or massive black holes. In such a potential orbit precession is commonly retrograde, i.e. direction of the orbit precession is opposite to the orbital…
This paper presents elements about the radial orbit instability, which occurs in spherical self-gravitating systems with a strong anisotropy in the radial velocity direction. It contains an overview on the history of radial orbit…
Our understanding of the Solar System has been revolutionized over the past decade by the finding that the orbits of the planets are inherently chaotic. In extreme cases, chaotic motions can change the relative positions of the planets…
The rotation rate of a star has important implications for the detectability, characterisation and stability of any planets that may be orbiting it. This chapter gives a brief overview of stellar rotation before describing the methods used…
Motivated by the current search for exomoons, this paper considers the stability of tidal equilibrium for hierarchical three-body systems containing a star, a planet, and a moon. In this treatment, the energy and angular momentum budgets…
We study orbital inclination changes associated with the precession of a disc-planet system that occurs through gravitational interaction with a binary companion on an inclined orbit. We investigate whether this scenario can account for…
A planet orbiting in a disk of planetesimals can experience an instability in which it migrates to smaller orbital radii. Resonant interactions between the planet and planetesimals remove angular momentum from the planetesimals, increasing…
We show that under certain astrophysical conditions a binary system consisting of two compact objects can be stabilized against indefinite shrinking of orbits due to the emission of gravitational radiation. In this case, the lighter binary…
Context: Seasonal variations and climate stability of a planet are very sensitive to the planet obliquity and its evolution. This is of particular interest for the emergence and sustainability of land-based life, but orbital and rotational…
Observations of circumstellar disks around stars as a function of stellar properties such as mass, metallicity, multiplicity, and age, provide constraints on theories concerning the formation and evolution of planetary systems. Utilizing…
Stars hosting hot Jupiters are often observed to have high obliquities, whereas stars with multiple co-planar planets have been seen to have low obliquities. This has been interpreted as evidence that hot-Jupiter formation is linked to…
Planets interact with their host stars through gravity, radiation and magnetic fields, and for those giant planets that orbit their stars within ~10 stellar radii (~0.1 AU for a sun-like star), star-planet interactions (SPI) are observable…
In previous work stable approximately axisymmetric equilibrium configurations for magnetic stars were found by numerical simulation. Here I investigate the conditions under which more complex, non-axisymmetric configurations can form. I…
Results on the obliquity of exoplanet host stars -- the angle between the stellar spin axis and the planetary orbital axis -- provide important diagnostic information for theories describing planetary formation. Here we present the first…
The orbits of binary stars precess as a result of general relativistic effects, forces arising from the asphericity of the stars, and forces from additional stars or planets in the system. For most binaries, the theoretical and observed…
We consider a $(1+N)$-body problem in which one particle has mass $m_0 \gg 1$ and the remaining $N$ have unitary mass. We can assume that the body with larger mass (central body) is at rest at the origin, coinciding with the center of mass…
About a dozen exoplanetary systems have been discovered with three or more planets participating in a sequence of mean-motion resonances. The unique and complex architectures of these so-called "resonant chains" motivate efforts to…
The rotation axis of the Sun is misaligned from the mean angular momentum plane of the Solar system by about 6 degrees. This obliquity significantly exceeds the ~1-2 degree distribution of inclinations among the planetary orbits and…