Solar system in perspective

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Solar system config

• Planetary orbits are coplanar
• suns equator close to orbit Plane
• nearly circular orbits
• planets all orbit in same direction
• most planets rotate in the same direction as their orbital motion

Porotstellar Neb

• Cloud of gas compressing and spinning

Compartive planetology

• Massive colder planets retain atmospheres
• planet masses and compositions were driven by the temperature gradient in the protoplanetary disk and its relation to the condensation Temperature profile

Origin of the solar system

• Giant jovian satellites are a mini version of the whole solar system
• rings are temporary and provide evidence for a dynamic, evolving planetary system \begin{list}{-}{}
• all Jovan planets have rings
• produced by bodies that failed to form or were disrupted due to tidal forces
• triton is scheduled to explode

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Dynamic solar system

• our moon, large satellite of a small planet
• triton captured by Neptune
• retrograde rotation of Venus
• large impact craters

Detecting exoplanets

Transit

• can theoretically resolve some based on angular resolution, but very hard to separate from the star itself
• $L_{jup}=(\frac{L_{\odot }}{r\pi a^2}(\pi R_{jup}^{2}A))$
• if you look at infrared radiation it is “easier” to resolve to planet

Indirect

• Wobble due to the planet pulling on the star
• They orbit their COM

Doppler effect

• Measure redshift and blue shift on the star

Unknown orbital inclination angle

• We do not know the inclination of the plane of the system relative to our line of sight
• Doppler can only measure velocities projected onto the line of sight
• if $i=90°$, the plane is viewed edge on, and we measure true veloicty. Otherwise, we measure a smaller velocity, giving a lower limit of planet masses.

Radial Velocity method

• we need the complete more accurate version of Kepler III
• $p^2=\frac{4{\pi }^2(a_A+a_B{)}^3}{G(M_A+M_B)}$
• can find $p$ by looking at when the velocity pattern repeats
• we want $a_b$ and $M_B$. get $a_B$ from
• $a_b^3\approx \frac{G{M}_A{P}^2}{4{\pi }^2}$ $M_A\gg M_B$
• $\frac{a_A}{a_B}=\frac{M_B}{M_A}$
• $M_B=(\frac{4{\pi }^2{M}_A^2}{G{P}^2}{a}_A^3{)}^{1/3}$

Transit method

• Detected by planet passing in front of the star, causing a dip in the brightness
• find mind transit flux reduction
• find planet velocity (same method at radial vel)
• time before $t_1$ and $t_2$ yields planet radius or measuring the fraction of the starlight blocked (if $r_s$ is known)

Chance of detection

• Range of inclinations for which transit is observed
• $\cos i\le \frac{R_A+R_B}{a}$

Surprising exoplanet discoveries

• Hot Jupiter’s - exoplanets with Jupiter like masses which are very close to their host stars
• very eccentric and/or inclined planet orbits
• current perspective biased by observational methods