Flashcards in Lecture 8 Deck (34):
What is strange about the "disappearing star" KIC 8462852?
There are irregular dips in the light output, suggesting something large is coming in front of the star periodicially
What is a Dyson sphere?
A suggested answer to the problem of the star dimming; a huge metal structure built to capture light
What properties of the solar system must the formation theory explain?
1. Formation of sun 2. Patterns of motion 3. exceptions 4. Existence of three types of planets 5. existence of smaller bodies
What were the two prevailing theories?
Nebular and close encounter
What was the nebular theory?
Theory that solar system formed when a cloud of dust collapsed
What was the close encounter hypothesis and why was it disproved?
It stated that a nearby star came in and caused large chunks of debris to form the planets; but can't be true because that is highly improbable and wouldn't account for the different patterns of motion
What is one example where we can see stars forming?
The Orion Nebula
How does contraction produce heat?
Friction and radiation of collapsing
Why should a cloud start collapsing?
After a cataclysmic event
What three things happen to a spinning cloud?
Heating, Spinning, Flattening
Why do collapsing clouds heat up?
Due to the gravitational energy
Why do collapsing clouds spin faster?
Due to the change in angular momentum
Why do collapsing clouds flatten?
Because as particles collide they form clumps, and this helps to organize the motion
What three things constrain the possibility of a collapse?
Low density, too hot, too large
What happens in star formation once the large cloud collapses?
Smaller clouds form due to various things, for example magnetic fields
What is interesting about view T Tauri star?
It is embedded in a nebula
What was the era of Heavy Bombardment?
The time when most craters formed
What are Herbig Haro objects?
Stellar jets of gas
Why did different types of planets form?
Due to the different temperatures at which compounds condense
What is the frost line?
The line which marks where hydrogen compounds may start to condense
How did the terrestrial planets form?
How did captured moons occur?
By random objects getting trapped in gravitational field
How can we tell if a moon is a captured moon?
Usually quite small, retrograde orbit, or tiled at a funky axis, funky shape
What are the four steps to planetary formation?
1. Dust sticks together
2. Orderly growth
3. Runaway growth
4. Oligarchic growth (of only certain planets)
Why do we suspect Itokawa is a planetesimal?
It has two distinct chunks that seemed to have formed together
How did the jovian planets form?
Ice condensed as well as other materials, and they got so big because they had a much larger area to sweep, and eventually could get even H and He to become part of their atmosphere
Why does migration occur after planets have formed?
Due to friction from the dust
What is type 1 migration?
Body slows down due to friction of being embedded in dust, slowly moves inward
What is type 2 migration?
Body gathers up more dust, affecting the mass and therefore angular momentum of the body
What is High Eccentricity Migration (HEM)?
Gravitational interaction with another body, kicking one out or in
What happens after all formation is done?
Solar wind blows dust and gas away, other factors contribute to blowing the disk away
When do comets and asteroids form?
After accretion, icy comets outside frost line, rocky asteroids inside frost line
Where did Earth's water come from?
Chondrites -- certain chemicals delivered during Heavy Bombardement