Astrophysics revision Flashcards
Universe definition
collection of billions of galaxies
Galaxy defintion
collection of billions of stars and their solar systems
Our solar system
the milky way
Thanks to gravitational force:
- moons orbit
- planets orbit
- artificial satellites orbit
- comets orbit
- planets
- the sun
- the earth
- the sun
Orbit of comets
- have elliptical orbits
- most kinetic, GPE and speed when closest to sun
- comet tail always points away from sun
Orbit of moons
- circular orbit
- tidally locked so same side of moon always faces the planet
- orbit matches with Earth’s rotation
Orbit of planets
- circular
orbital speed formula
orbital speed:
2 x π x orbital radius
over
Time period
How can stars be classified based on colour and whats the order highest to lowest.
Color based on surface temp:
Dark blue, lighter blue, white, light yellow, yellow, orange, red
Stages of a star similar/ smaller mass than Sun and brief description of each
- nebula - clouds of gas and dust which contact under gravity
- main sequence - stable and fusing hydrogen to form helium. Gravity vs radiation pressure
- red giant - hydrogen core runs out, pressure contracts core, produces carbon and oxygen, lots of energy produced
- white dwarf - the hot dense solid core left behind
- black dwarf - white dwarf cools to leave black dwarf
Stages of star larger than Sun
- becomes a red supergiant instead, which produces enough energy to form heavier elements (up to iron)
- runs out of fuel, core collapses, supernova explosion where elements heavier than iron form
- core becomes a neutron star, or star becomes a black hole
What is absolute magnitude
How bright a star would appear if it were 10 parsecs away. Reverse scale (lower number means brighter)
Axis of a hertzsprung-russel diagram
x axis - temp
y axis - absolute magnitude
Two most important arguments supporting Big Bang Theory
Cosmic microwave background radiation and red shift
Time line of the universe
universe heated up, cooled down, expanded, created stars and stuff
