Cosmology Flashcards
To learn the relevant information for the course
What is the Doppler Effect?
The change in frequency of light and sound in relation to the observer. Red is expanding - moving away where as blue is compressed - moving towards us.
What evidence is there for the universe expanding?
Hubble saw that light from all other galaxies was red shifted (spread out), therefore he deduced that the universe was expanding.
Describe the formation of simple elements at the start of the universe.
Clouds of interstellar dust formed such as hydrogen (colliding to make –) and helium were formed due to gravitational attraction.
They flatten out to create a nebula - rotating disk
Then due to the eventual accumulation of material, more hydrogen particles collide with one another, the gravitational field grows stronger (since the mass of the nebula is increasing). This eventually causes the nebula to become hotter and hotter in the centre.
Eventually it grows hot enough to produce more complex elements and stars.
What are these early stars called (after nebula)
These are known as proto stars
What’s the term used when heavier elements (C - Fe are formed) and what’s the biggest star Which’ll allow this fusion without collapsing.
Heavier elements are formed via Stella nuclear synthesis, this means they’re formed from nuclear fusion within stars.
The biggest star (which produces Iron) is a red super giant.
How are elements heavier than Iron created?
When a star get’s bigger than red supergiants they collapse and produce supernovas, this is where elements heavier than Iron are produced.
How are planets formed?
They’re formed through a process called accretion which involves a progressive collision of smaller particles to form larger particles.
What’s the frost line?
The frost line divides the inner and outer part of the solar system.
Inside the frost line it’s too hot for hydrogen compounds to form gases.
Outside the frost line it’s cold enough for ices to form.
Why are the inner rocky planets ‘layered’? Two processes!
A) Denser material accreated first and then the less denser material.
B) The earth began fairly homogeneous however over time the lighter material rose to the top - i.e the crust.
How was the moon formed?
A proto planet crashed in to earth and then got stuck in earth’s orbit, over time though accreation it turned in to the moon we know today.
How can we see planets in distant galaxies?
We observe the small fluctuations in the light spectrum of stars caused by the gravitational pull of neighbouring planets.
How do hot jupiters (gaseous) have orbits close to stars?
Hot Jupiters change their orbit (due to a new planet changing orbits etc) and then the orbit stabilizes closer to the start and starts to heat up.
How do we measure distances in space?
We use the Angstrom Unit - 1 Au is the distance from the earth to the sun.
What are asteroids and where do they come from?
Asteroids are small bodies of rock orbiting the sun. They come from the kupiter belt!
What are comits and why do they have tails?
They are small bodies of ice, dust, carbon dioxide etc. The tail is made as the matter evaporates as the sun heats it up.
