Notes

Just a few things:

Poynting–Robertson drag: solar radiation will cause dust grains to spiral inward.

From the perspective of the dust grain, solar radiation appears to be coming from a slightly forward direction. This is the aberration of light; at the instant of any observation of an object, the apparent position of the object (the sun) is displaced (see figure below). Absorbing this light leads to a force component against the direction of movement.

From the perspective of the solar system (the other reference frame), the dust absorbs sunlight in only the radial direction and its angular momentum is unchanged. However, by absorbing the photons it gains mass, and to conserve angular momentum L = r x mv, the dust must drop to a lower orbit.

Light from location 1 will appear to be coming from location 2 for a moving telescope due to the finite speed of light, a phenomenon known as the aberration of light.

Rossiter-McLaughlin effect: changes in the mean redshift of a star due to an eclipsing binary's secondary star or an extrasolar planet during transit.

A star's rotation means that at any time, one quadrant of its photosphere will be seen coming towards the viewer, and one quadrant moving away. These motions produce blueshifts and redshifts, respectively, which we observe only as spectral line broadening. However, during transit, the orbiting object blocks part of the disk, preventing some of the shifted light from reaching the observer and changing the observed mean redshift, resulting in a positive-to-negative anomaly if the orbit is prograde, and vice versa if the orbit is retrograde.

The view is situated at the bottom. The light is blueshifted on the approaching side and redshifted on the receding side. As the planet passes in front of the star it causes the star's apparent radial velocity to change.

This effect has been used to show that as many as 25% of hot Jupiters are orbiting in a retrograde direction with respect to their parents stars, strongly suggesting that dynamical interactions, rather than planetary migration, produce these objects. For cool stuff on misaligned orbits of hot Jupiters, see this.

Actually, I'll overview the link a bit. ESO claimed that "Most hot Jupiters are misaligned...the histogram of projected obliquities matches closely the theoretical distributions of using Kozai cycles and tidal friction...most hot Jupiters are formed by this very mechanism without the need to use type I or II migration." Greg Laughlin, a professor at UCSC, discusses this and comes to the conclusion that Kozai-migration, well understood for HD80606 (and explained very nicely in the post), "plays a larger role is sculpting the planet distribution than previously believed."

Electron degeneracy pressure: electrons compressed in tiny volumes gain large momentum and repulsive force

The Pauli Exclusion Principle disallows two half integer spin particles from occupying the same quantum state at a given time, so there is a resultant repulsive force manifested as a pressure against compression of matter into smaller volumes of space. To add another electron to a given volume requires raising an electron's energy level to make room --> requirement for energy to compress the material appears as pressure.

Solid matter is...solid because of this degeneracy, instead of electrostatic repulsion. For stars which are sufficiently large, electron degeneracy pressure is not enough to prevent them from collapsing under their own weight once nuclear fusion has ceased, and then neutron degeneracy pressure prevents the star from collapsing further. In a nonrelativistic material, this is computed as:

This pressure is in addition to the normal gas pressure P = nkT / V,  and neglected unless the density (proportional to n/V) is high enough and the temperature is low enough.

The Heisenberg uncertainty principle   lets us see that as matter is condensed (uncertainty in position decreases) the momenta uncertainty increases and the electrons must be traveling at a certain speed. When the pressure due to this speed exceed that of the pressure from the thermal motions of the electrons, the electrons are degenerate.

Electron degeneracy pressure will halt the gravitational collapse of a star if its mass is below the Chandrasekhar Limit (1.38 solar masses). This pressure prevents a white dwarf from collapsing. After the limit, the star will collapse to either a neutron star or black hole (gravity).

Paucity of intelligent life: part of this
We've highly overestimated intelligent, technologically advanced life (they would have come knocking). Why? One reason is that there is no evolutionary pressure to gain technology; another is that the lifespan of an 'advanced' civilization is perhaps on a very small order, and that they die out quickly.

Heliosphere map and IBEX: listen to this short 2009 broadcast

The sun's corona boils off into space, producing the solar wind of hot ionized gas, flowing out at a million miles an hour. This inflates the bubble of the heliosphere. IBEX, the interstellar boundary explorer, measures neutral particles that propagate in from the outer reaches of the heliosphere, about 10 billion miles out. In the space between the termination shock and the ISM, the gas becomes heated and slower. The neutralized particles are produced in this interaction region between solar-material and outer-space material. IBEX took 6 months to map these particles.

It was expected to see a variation in the particle flux, relatively small (tens of percent) and to vary over  large angular ranges. Instead, there is very narrow 'ribbon' in the sky, where the flux is two or three times of anywhere else. The ribbon appears to line up with the external magnetic field (outside of the solar field) where it drapes around and squeezes hardest on our heliosphere. Most likely, the ribbon of incoming particles is correlated to the higher density of particles outside.

Hill sphere: the region around a body where it dominates the attraction of satellites

Lies between L1 and L2, although the true region of stable satellite orbit is inside 1/2 or 1/3 of this and dependent on other forces (radiation pressure, Yarkovsky effect). Note that retrograde orbits at a wider orbit are more stable than prograde orbits. Also, in any very loworbit, a spherical body must be extremely dense in order to fit inside its own Hill sphere and be capable of supporting an orbit.

Yarkovsky effect: for small bodies (d<10km) a force caused by anisotopic thermal emmision (photons with momentum)

Roche limit: the radius at which an (only) gravitationally-bound satellite disintegrates by tidal forces.

If held together by their tensile strength (Jupiter's Metis and Saturn's Pan) satellites can orbit within their Roche limits. Almost all planetary rings are located within their Roche limit, with Saturn's E Ring and Phoebe ring being notable exceptions.

Roche lobe: the region around a star which orbiting material is gravitationally bound to the star.
If the star expands past its Roche lobe, material can escape. In a binary system escaped material will fall in through the inner Lagrangian point (mass transfer).

Vis Viva: orbital energy conservation equation; for any Kepler orbit (elliptic, parabolic, hyperbolic, or radial), the vis viva equation is , where v is the relative speed of the two bodies, r is the distance between them, and a is the semimajor axis (a>0 for ellipses, a=∞ for parabolas, and a<0 for hyperbolas).

Redshift: 

Surface Gravity: the luminosity of a star L* goes as logg*.

Kozai mechanism: the periodic exchange between inclination and eccentricity; see this.

It is a secular interaction between a wide-binary companion and a planet, in a triple system. When the relative inclination angle between the two orbital planes is greater than 39.2 degrees, known as the Kozai angle, a cyclic and long-term exchange of angular momentum occurs between the planet and more distant companion.

For an orbiting body with eccentricity e and inclination i,   is conserved. A perturbation may lead to a resonance between the two. Typcally, this results in the precession of the argument of pericenter, which then librates (oscillates) around either 90° or 270°. Increasing eccentricity while keeping the semimajor axis constant reduces the periapsis distance (the distance at closest approach), and the periapse occurs when the body is at highest inclination. The maximum eccentricity reached is independent of orbital parameters like mass and period: .

Oribital parameters, mass and semimajor axes only affect the period of the Kozai cycles. This is estimated as , where the indices are 0) central star, 1) planet, and 2) binary companion. If the Kozai period is large, it is highly unlikely the planet is highly eccentric at a given point in time. The binary companions are probably either a brown dwarf (larger orbital range, mass can approach Jupiter masses) and main-sequence dwarfs, about the mass of the sun. The Kozai period is inversely proportional to the mass of the binary companion, so oscillation periods of brown-dwarf companion systems are hundreds of times longer than that of a main-sequence dwarf star.


Just some things I should understand. :P