Solar System and Exoplanets Flashcards
What are the components of the Solar System?
The Sun
The eight planets and their moons and ring systems
Asteroids, comets, dust, the Keiper belt and the Oort cloud
What is the temperature of a body in a system in thermal equilibrium?
T=L_star/(16πσd^2))^1/4
Where d is the distance to the star
What are the rocky planets?
The inner planets
Core made from metals
Mantle made from silicates
Secondary Atmospheres
What are the gas giants?
Have lower density
Hydrogen and helium composition
Core made from iron and nickel and silicates
Atmospheres are primary
All have many moons
What is an exoplanet?
A planet that orbits a star other than the Sun
Why are exoplanets difficult to detect from Earth?
They appear very faint and are very close to their host star
What is the radial velocity method?
A way to find exoplanets
We have r1=M2r2/M1
We then have v1=2πr1/P2
So finding v1 we can use this velocity and a spectrograph to detect a fractional wavelength shift of v1/c
What is the transit method?
When the exoplanet transits across the stellar disk, there is a periodic dip in the apparent flux of the star of depth δ
δ=(Rp/Rs)^2
Where p means planet and s means star
How is the transit method biased?
Leans towards detecting exoplanets with larger radii
What is the duration of the transit?
D=Psin^-1((Rp+Rs)/a)/π
Where a is the orbital radius
What is the difficulty of direct imaging?
Planets emit very little light and lie at small angular separations from their host stars
How many exoplanets have been discovered?
Over 5000
