science exam Flashcards
What is step one in a stars life cycle?
NEBULA
- Stars start in a cloud of dust called a nebula
- Nebulae are multiple light years across and can spawn multiple star systems.
- Dust and gas move together under gravity and begin to spin as a disk.
what is step 2 in a stars life cycle?
PROTOSTAR
- a ball of mass starts to form in the centre of the disk from step 1
- when the mass gets larger and larger, the ball gets hotter and starts to glow forming a protostar
- The temperature continues to rise and eventually gets hot enough for nuclear fusion to begin.
What is step 3 in a stars life cycle?
MAIN SEQUENCE
- The star will fuse Hydrogen in a more-or-less stable fashion.
- Bigger stars tend to use their fuel faster (because of the pressure)
- A star can be in the main sequence anywhere between 20 million to 80 billion years.
what is step 4 in a stars life cycle?
RED SUPERGIANT OR RED GIANT
- Stars eventually use up all their Hydrogen and do one of 3 things depending on their mass
what happens to high mass stars during step 4?
The highest mass stars will begin to fuse Helium and expand into a Red Supergiant star.
what happens to medium mass stars during step 4?
The medium mass stars also fuse Helium and expand, but only to the size of a Red Giant (the size of a large star)
what happens to low mass stars during step 4?
The lowest mass stars will skip this step entirely (fusing Helium) and collapse into a white dwarf.
what do red giants and red supergiants do throughout their lifetime?
Red Giants and Red Supergiants expand about 500x their original size.
what is step 5 in a stars life cycle?
SUPERNOVA OR WHITE DWARF
Once the Helium is used up (from high or medium mass stars), a star will do one of 2 things:
1: The star will collapse, but re-gain enough pressure in its core to fuse heavier elements. the result of this pressure is a supernova.
2: The star will collapse and be unable to fuse anything else. It will slowly cool and radiate heat as a White Dwarf until it becomes a Brown Dwarf (cold).
What is step 6 in a stars life cycle?
NEUTRON STAR OR BLACK HOLE
If a star goes supernova, it will do one of 2 things depending on their mass:
1: The core will become a ball of mass so dense it becomes a neutron star.
2: The core will become a ball of mass that is even more dense that it becomes a black hole.
how does a star become a supernova in its life cycle?
once the helium is used up, the high or medium mass star will collapse, but re-gain enough pressure in its core to fuse heavier elements. the result of this pressure is a supernova.
how does a star become a brown dwarf?
once the helium is used up, the high or medium mass star will collapse and be unable to fuse anything else. It will slowly cool and radiate heat as a White Dwarf until it becomes a Brown Dwarf (cold).
what is star class m?
Temp: 2,500 - 3,500
Colour: red
What are the star classes g and f?
temp: 5000 - 7500
colour: yellow
What is star class k?
temp: 3500-5000
colour: orange
what is the star class a?
Temp: 7500 - 10,000
Colour: white
What are the star classes o and b?
Temp: 10,000 - 50,000
Colour: blue
what is the order of star classes from coldest to hottest?
M
K
G, F
A
B, O
what are the two variables that control a stars formation?
Mass and temperature
what are the forces that control and stars formation?
gravity and pressure
what is the big bang theory?
- The entire universe formed from a single dense point which suddenly expanded.
- The universe, and time itself, began 13.9 billion years ago and all the matter and energy in the universe came from the Big Bang.
who came up with the big bang theory?
Edwin Hubble
what was Hubble’s evidence for the big bang theory?
1: Hubble studied the light spectrum of each galaxy and calculated
a) The speed the galaxy was moving away from our Milky Way Galaxy and
b) The distance of the galaxy from our own galaxy
2: He discovered a relationship between these two measurements:
The farther away a galaxy was from our own, the faster it was moving away.
This shows that the universe is expanding.
what is the particle theory?
All Matter is made up of tiny particles that have empty spaces between them.
what are the spacing, forces and motion in a solid property?
very close together in a pattern
strong attraction
particles vibrate in a fixed position