Ch16 Space Flashcards
Formation of a protostar
Particles in a nebula(cloud of dust and gas) are pulled together by the force of gravity
Clouds merge together, becoming more concentrated to form a protostar
What happens to a protostar to make a main sequence star
As the protostaar becomes more dense, the particles speed up and collide more so the temperature increases
When the temperature becomes high enough, hydrogen nuclei undergo nuclear fusion to form helium nuclei
Energy is released, keeping the core hot
What is a main sequence star?
Long stable period where the outward force of nuclear fusion(expansion) is in equilibrium with the force of gravity pulling everything inwards(contraction)
The bigger the star, the shorter the main sequence
It radiates energy because hydrogen fusion in the core
How does a red (super) giant form?
The main sequence star runs out of hydrogen nuclei
The core collapses and the outer layer swells
The surface cools and turns red
The fusion of helium(+ other elements) occur to form heavier elements(up to iron) in the core
How does a white dwarf form?
When there are no more light elements in the core of a small-medium sized red giant, fusion stops and radiation stops
The star becomes unstable, collapses and ejects outer layer of dust and gas
It heats up and turns form red to white
It is now a hot, dense, solid core called a white dwarf
How does a black dwarf from?
White dwarf cools down and emits less energy, fading out
How does a supernova form?
Red super giants undergo more fusion, glow bright and contract and expand several times,
It forms elements as heavy as iron in various nuclear reactions
Eventually it will cataclysmically explode into a supernova
How do new planets and stars form?
When a red super giant explodes into a supernova, the heavy elements made are ejected into the universe to form new planets and stars
How are neutron stars formed?
Exploding supernova throws outer layer of dust and gas into space
The core of the star compresses, leaving a very dense core made up of only neutrons
How are black holes formed?
If star is big enough, it becomes a black hole instead of a neutron star
It is a very super dense point with a gravitational field strength so strong nothing can escape from it
Big Crunch
If density of universe is more than particular amount, it will stop expanding and reverse
Big Yawn
If density of universe is less than a particular amount, it will expand forever
Stars and everything else will die out
Dark matter
Missing mass that can’t be seen
Galaxies would be spinning much faster if stars were the only matter
Evidence for big bang
1) Big Bang created high energy gamma radiation. As the universe expanded, the wavelengths stretched out to create low energy cosmic background radiation in every direction in space
Detected in 1965
2) Red-shift- provides evidence the universe is expanding
Red Shift
Use a prism to split light into a spectrum(blue to red)
Wavelengths of waves increase if the body is moving away
Spectrum of light is shifted towards the red part of the spectrum
Blue Shift
Use a prism to split light into a spectrum(blue to red)
Wavelengths of waves decrease if the body is moving towards you
Spectrum of light is shifted towards the blue part of the spectrum
Solar mass
1M0 = 1.99 x 10^30kg
The mass of our sun
Average temperature in space
4 Kelvin
-269.15 degrees Celsius
Age of Universe
13 billion years old(+ or - 1 billion years)
Shift rule
The faster a star or galaxy is moving relative to you, the bigger the shift is
Steady State Theory
Galaxies are being pushed apart because of matter entering the universe through ‘white holes’
Further the smaller body is from the bigger body
- the less particular speed needed because the force of gravity is weaker
- The longer the orbiting body takes to orbit around once because the circumference is bigger
Order of the planet from the sun
Mercury - my Venus - very Earth - easy Mars - method Jupiter - just Saturn- speeds Uranus - up Neptune - nothing
Who discovered the expanding universe and when
Edwin Hubble in 1929
